linux/kernel/trace/trace.c
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   1/*
   2 * ring buffer based function tracer
   3 *
   4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   6 *
   7 * Originally taken from the RT patch by:
   8 *    Arnaldo Carvalho de Melo <acme@redhat.com>
   9 *
  10 * Based on code from the latency_tracer, that is:
  11 *  Copyright (C) 2004-2006 Ingo Molnar
  12 *  Copyright (C) 2004 Nadia Yvette Chambers
  13 */
  14#include <linux/ring_buffer.h>
  15#include <generated/utsrelease.h>
  16#include <linux/stacktrace.h>
  17#include <linux/writeback.h>
  18#include <linux/kallsyms.h>
  19#include <linux/seq_file.h>
  20#include <linux/notifier.h>
  21#include <linux/irqflags.h>
  22#include <linux/irq_work.h>
  23#include <linux/debugfs.h>
  24#include <linux/pagemap.h>
  25#include <linux/hardirq.h>
  26#include <linux/linkage.h>
  27#include <linux/uaccess.h>
  28#include <linux/kprobes.h>
  29#include <linux/ftrace.h>
  30#include <linux/module.h>
  31#include <linux/percpu.h>
  32#include <linux/splice.h>
  33#include <linux/kdebug.h>
  34#include <linux/string.h>
  35#include <linux/rwsem.h>
  36#include <linux/slab.h>
  37#include <linux/ctype.h>
  38#include <linux/init.h>
  39#include <linux/poll.h>
  40#include <linux/nmi.h>
  41#include <linux/fs.h>
  42#include <linux/sched/rt.h>
  43
  44#include "trace.h"
  45#include "trace_output.h"
  46
  47/*
  48 * On boot up, the ring buffer is set to the minimum size, so that
  49 * we do not waste memory on systems that are not using tracing.
  50 */
  51int ring_buffer_expanded;
  52
  53/*
  54 * We need to change this state when a selftest is running.
  55 * A selftest will lurk into the ring-buffer to count the
  56 * entries inserted during the selftest although some concurrent
  57 * insertions into the ring-buffer such as trace_printk could occurred
  58 * at the same time, giving false positive or negative results.
  59 */
  60static bool __read_mostly tracing_selftest_running;
  61
  62/*
  63 * If a tracer is running, we do not want to run SELFTEST.
  64 */
  65bool __read_mostly tracing_selftest_disabled;
  66
  67/* For tracers that don't implement custom flags */
  68static struct tracer_opt dummy_tracer_opt[] = {
  69        { }
  70};
  71
  72static struct tracer_flags dummy_tracer_flags = {
  73        .val = 0,
  74        .opts = dummy_tracer_opt
  75};
  76
  77static int dummy_set_flag(u32 old_flags, u32 bit, int set)
  78{
  79        return 0;
  80}
  81
  82/*
  83 * To prevent the comm cache from being overwritten when no
  84 * tracing is active, only save the comm when a trace event
  85 * occurred.
  86 */
  87static DEFINE_PER_CPU(bool, trace_cmdline_save);
  88
  89/*
  90 * When a reader is waiting for data, then this variable is
  91 * set to true.
  92 */
  93static bool trace_wakeup_needed;
  94
  95static struct irq_work trace_work_wakeup;
  96
  97/*
  98 * Kill all tracing for good (never come back).
  99 * It is initialized to 1 but will turn to zero if the initialization
 100 * of the tracer is successful. But that is the only place that sets
 101 * this back to zero.
 102 */
 103static int tracing_disabled = 1;
 104
 105DEFINE_PER_CPU(int, ftrace_cpu_disabled);
 106
 107cpumask_var_t __read_mostly     tracing_buffer_mask;
 108
 109/*
 110 * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
 111 *
 112 * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
 113 * is set, then ftrace_dump is called. This will output the contents
 114 * of the ftrace buffers to the console.  This is very useful for
 115 * capturing traces that lead to crashes and outputing it to a
 116 * serial console.
 117 *
 118 * It is default off, but you can enable it with either specifying
 119 * "ftrace_dump_on_oops" in the kernel command line, or setting
 120 * /proc/sys/kernel/ftrace_dump_on_oops
 121 * Set 1 if you want to dump buffers of all CPUs
 122 * Set 2 if you want to dump the buffer of the CPU that triggered oops
 123 */
 124
 125enum ftrace_dump_mode ftrace_dump_on_oops;
 126
 127static int tracing_set_tracer(const char *buf);
 128
 129#define MAX_TRACER_SIZE         100
 130static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
 131static char *default_bootup_tracer;
 132
 133static int __init set_cmdline_ftrace(char *str)
 134{
 135        strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
 136        default_bootup_tracer = bootup_tracer_buf;
 137        /* We are using ftrace early, expand it */
 138        ring_buffer_expanded = 1;
 139        return 1;
 140}
 141__setup("ftrace=", set_cmdline_ftrace);
 142
 143static int __init set_ftrace_dump_on_oops(char *str)
 144{
 145        if (*str++ != '=' || !*str) {
 146                ftrace_dump_on_oops = DUMP_ALL;
 147                return 1;
 148        }
 149
 150        if (!strcmp("orig_cpu", str)) {
 151                ftrace_dump_on_oops = DUMP_ORIG;
 152                return 1;
 153        }
 154
 155        return 0;
 156}
 157__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
 158
 159
 160static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
 161static char *trace_boot_options __initdata;
 162
 163static int __init set_trace_boot_options(char *str)
 164{
 165        strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
 166        trace_boot_options = trace_boot_options_buf;
 167        return 0;
 168}
 169__setup("trace_options=", set_trace_boot_options);
 170
 171unsigned long long ns2usecs(cycle_t nsec)
 172{
 173        nsec += 500;
 174        do_div(nsec, 1000);
 175        return nsec;
 176}
 177
 178/*
 179 * The global_trace is the descriptor that holds the tracing
 180 * buffers for the live tracing. For each CPU, it contains
 181 * a link list of pages that will store trace entries. The
 182 * page descriptor of the pages in the memory is used to hold
 183 * the link list by linking the lru item in the page descriptor
 184 * to each of the pages in the buffer per CPU.
 185 *
 186 * For each active CPU there is a data field that holds the
 187 * pages for the buffer for that CPU. Each CPU has the same number
 188 * of pages allocated for its buffer.
 189 */
 190static struct trace_array       global_trace;
 191
 192static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
 193
 194int filter_current_check_discard(struct ring_buffer *buffer,
 195                                 struct ftrace_event_call *call, void *rec,
 196                                 struct ring_buffer_event *event)
 197{
 198        return filter_check_discard(call, rec, buffer, event);
 199}
 200EXPORT_SYMBOL_GPL(filter_current_check_discard);
 201
 202cycle_t ftrace_now(int cpu)
 203{
 204        u64 ts;
 205
 206        /* Early boot up does not have a buffer yet */
 207        if (!global_trace.buffer)
 208                return trace_clock_local();
 209
 210        ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
 211        ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
 212
 213        return ts;
 214}
 215
 216/*
 217 * The max_tr is used to snapshot the global_trace when a maximum
 218 * latency is reached. Some tracers will use this to store a maximum
 219 * trace while it continues examining live traces.
 220 *
 221 * The buffers for the max_tr are set up the same as the global_trace.
 222 * When a snapshot is taken, the link list of the max_tr is swapped
 223 * with the link list of the global_trace and the buffers are reset for
 224 * the global_trace so the tracing can continue.
 225 */
 226static struct trace_array       max_tr;
 227
 228static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
 229
 230int tracing_is_enabled(void)
 231{
 232        return tracing_is_on();
 233}
 234
 235/*
 236 * trace_buf_size is the size in bytes that is allocated
 237 * for a buffer. Note, the number of bytes is always rounded
 238 * to page size.
 239 *
 240 * This number is purposely set to a low number of 16384.
 241 * If the dump on oops happens, it will be much appreciated
 242 * to not have to wait for all that output. Anyway this can be
 243 * boot time and run time configurable.
 244 */
 245#define TRACE_BUF_SIZE_DEFAULT  1441792UL /* 16384 * 88 (sizeof(entry)) */
 246
 247static unsigned long            trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
 248
 249/* trace_types holds a link list of available tracers. */
 250static struct tracer            *trace_types __read_mostly;
 251
 252/* current_trace points to the tracer that is currently active */
 253static struct tracer            *current_trace __read_mostly = &nop_trace;
 254
 255/*
 256 * trace_types_lock is used to protect the trace_types list.
 257 */
 258static DEFINE_MUTEX(trace_types_lock);
 259
 260/*
 261 * serialize the access of the ring buffer
 262 *
 263 * ring buffer serializes readers, but it is low level protection.
 264 * The validity of the events (which returns by ring_buffer_peek() ..etc)
 265 * are not protected by ring buffer.
 266 *
 267 * The content of events may become garbage if we allow other process consumes
 268 * these events concurrently:
 269 *   A) the page of the consumed events may become a normal page
 270 *      (not reader page) in ring buffer, and this page will be rewrited
 271 *      by events producer.
 272 *   B) The page of the consumed events may become a page for splice_read,
 273 *      and this page will be returned to system.
 274 *
 275 * These primitives allow multi process access to different cpu ring buffer
 276 * concurrently.
 277 *
 278 * These primitives don't distinguish read-only and read-consume access.
 279 * Multi read-only access are also serialized.
 280 */
 281
 282#ifdef CONFIG_SMP
 283static DECLARE_RWSEM(all_cpu_access_lock);
 284static DEFINE_PER_CPU(struct mutex, cpu_access_lock);
 285
 286static inline void trace_access_lock(int cpu)
 287{
 288        if (cpu == TRACE_PIPE_ALL_CPU) {
 289                /* gain it for accessing the whole ring buffer. */
 290                down_write(&all_cpu_access_lock);
 291        } else {
 292                /* gain it for accessing a cpu ring buffer. */
 293
 294                /* Firstly block other trace_access_lock(TRACE_PIPE_ALL_CPU). */
 295                down_read(&all_cpu_access_lock);
 296
 297                /* Secondly block other access to this @cpu ring buffer. */
 298                mutex_lock(&per_cpu(cpu_access_lock, cpu));
 299        }
 300}
 301
 302static inline void trace_access_unlock(int cpu)
 303{
 304        if (cpu == TRACE_PIPE_ALL_CPU) {
 305                up_write(&all_cpu_access_lock);
 306        } else {
 307                mutex_unlock(&per_cpu(cpu_access_lock, cpu));
 308                up_read(&all_cpu_access_lock);
 309        }
 310}
 311
 312static inline void trace_access_lock_init(void)
 313{
 314        int cpu;
 315
 316        for_each_possible_cpu(cpu)
 317                mutex_init(&per_cpu(cpu_access_lock, cpu));
 318}
 319
 320#else
 321
 322static DEFINE_MUTEX(access_lock);
 323
 324static inline void trace_access_lock(int cpu)
 325{
 326        (void)cpu;
 327        mutex_lock(&access_lock);
 328}
 329
 330static inline void trace_access_unlock(int cpu)
 331{
 332        (void)cpu;
 333        mutex_unlock(&access_lock);
 334}
 335
 336static inline void trace_access_lock_init(void)
 337{
 338}
 339
 340#endif
 341
 342/* trace_wait is a waitqueue for tasks blocked on trace_poll */
 343static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
 344
 345/* trace_flags holds trace_options default values */
 346unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
 347        TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
 348        TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |
 349        TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS;
 350
 351static int trace_stop_count;
 352static DEFINE_RAW_SPINLOCK(tracing_start_lock);
 353
 354/**
 355 * trace_wake_up - wake up tasks waiting for trace input
 356 *
 357 * Schedules a delayed work to wake up any task that is blocked on the
 358 * trace_wait queue. These is used with trace_poll for tasks polling the
 359 * trace.
 360 */
 361static void trace_wake_up(struct irq_work *work)
 362{
 363        wake_up_all(&trace_wait);
 364
 365}
 366
 367/**
 368 * tracing_on - enable tracing buffers
 369 *
 370 * This function enables tracing buffers that may have been
 371 * disabled with tracing_off.
 372 */
 373void tracing_on(void)
 374{
 375        if (global_trace.buffer)
 376                ring_buffer_record_on(global_trace.buffer);
 377        /*
 378         * This flag is only looked at when buffers haven't been
 379         * allocated yet. We don't really care about the race
 380         * between setting this flag and actually turning
 381         * on the buffer.
 382         */
 383        global_trace.buffer_disabled = 0;
 384}
 385EXPORT_SYMBOL_GPL(tracing_on);
 386
 387/**
 388 * tracing_off - turn off tracing buffers
 389 *
 390 * This function stops the tracing buffers from recording data.
 391 * It does not disable any overhead the tracers themselves may
 392 * be causing. This function simply causes all recording to
 393 * the ring buffers to fail.
 394 */
 395void tracing_off(void)
 396{
 397        if (global_trace.buffer)
 398                ring_buffer_record_off(global_trace.buffer);
 399        /*
 400         * This flag is only looked at when buffers haven't been
 401         * allocated yet. We don't really care about the race
 402         * between setting this flag and actually turning
 403         * on the buffer.
 404         */
 405        global_trace.buffer_disabled = 1;
 406}
 407EXPORT_SYMBOL_GPL(tracing_off);
 408
 409/**
 410 * tracing_is_on - show state of ring buffers enabled
 411 */
 412int tracing_is_on(void)
 413{
 414        if (global_trace.buffer)
 415                return ring_buffer_record_is_on(global_trace.buffer);
 416        return !global_trace.buffer_disabled;
 417}
 418EXPORT_SYMBOL_GPL(tracing_is_on);
 419
 420static int __init set_buf_size(char *str)
 421{
 422        unsigned long buf_size;
 423
 424        if (!str)
 425                return 0;
 426        buf_size = memparse(str, &str);
 427        /* nr_entries can not be zero */
 428        if (buf_size == 0)
 429                return 0;
 430        trace_buf_size = buf_size;
 431        return 1;
 432}
 433__setup("trace_buf_size=", set_buf_size);
 434
 435static int __init set_tracing_thresh(char *str)
 436{
 437        unsigned long threshold;
 438        int ret;
 439
 440        if (!str)
 441                return 0;
 442        ret = kstrtoul(str, 0, &threshold);
 443        if (ret < 0)
 444                return 0;
 445        tracing_thresh = threshold * 1000;
 446        return 1;
 447}
 448__setup("tracing_thresh=", set_tracing_thresh);
 449
 450unsigned long nsecs_to_usecs(unsigned long nsecs)
 451{
 452        return nsecs / 1000;
 453}
 454
 455/* These must match the bit postions in trace_iterator_flags */
 456static const char *trace_options[] = {
 457        "print-parent",
 458        "sym-offset",
 459        "sym-addr",
 460        "verbose",
 461        "raw",
 462        "hex",
 463        "bin",
 464        "block",
 465        "stacktrace",
 466        "trace_printk",
 467        "ftrace_preempt",
 468        "branch",
 469        "annotate",
 470        "userstacktrace",
 471        "sym-userobj",
 472        "printk-msg-only",
 473        "context-info",
 474        "latency-format",
 475        "sleep-time",
 476        "graph-time",
 477        "record-cmd",
 478        "overwrite",
 479        "disable_on_free",
 480        "irq-info",
 481        "markers",
 482        NULL
 483};
 484
 485static struct {
 486        u64 (*func)(void);
 487        const char *name;
 488        int in_ns;              /* is this clock in nanoseconds? */
 489} trace_clocks[] = {
 490        { trace_clock_local,    "local",        1 },
 491        { trace_clock_global,   "global",       1 },
 492        { trace_clock_counter,  "counter",      0 },
 493        ARCH_TRACE_CLOCKS
 494};
 495
 496int trace_clock_id;
 497
 498/*
 499 * trace_parser_get_init - gets the buffer for trace parser
 500 */
 501int trace_parser_get_init(struct trace_parser *parser, int size)
 502{
 503        memset(parser, 0, sizeof(*parser));
 504
 505        parser->buffer = kmalloc(size, GFP_KERNEL);
 506        if (!parser->buffer)
 507                return 1;
 508
 509        parser->size = size;
 510        return 0;
 511}
 512
 513/*
 514 * trace_parser_put - frees the buffer for trace parser
 515 */
 516void trace_parser_put(struct trace_parser *parser)
 517{
 518        kfree(parser->buffer);
 519}
 520
 521/*
 522 * trace_get_user - reads the user input string separated by  space
 523 * (matched by isspace(ch))
 524 *
 525 * For each string found the 'struct trace_parser' is updated,
 526 * and the function returns.
 527 *
 528 * Returns number of bytes read.
 529 *
 530 * See kernel/trace/trace.h for 'struct trace_parser' details.
 531 */
 532int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 533        size_t cnt, loff_t *ppos)
 534{
 535        char ch;
 536        size_t read = 0;
 537        ssize_t ret;
 538
 539        if (!*ppos)
 540                trace_parser_clear(parser);
 541
 542        ret = get_user(ch, ubuf++);
 543        if (ret)
 544                goto out;
 545
 546        read++;
 547        cnt--;
 548
 549        /*
 550         * The parser is not finished with the last write,
 551         * continue reading the user input without skipping spaces.
 552         */
 553        if (!parser->cont) {
 554                /* skip white space */
 555                while (cnt && isspace(ch)) {
 556                        ret = get_user(ch, ubuf++);
 557                        if (ret)
 558                                goto out;
 559                        read++;
 560                        cnt--;
 561                }
 562
 563                /* only spaces were written */
 564                if (isspace(ch)) {
 565                        *ppos += read;
 566                        ret = read;
 567                        goto out;
 568                }
 569
 570                parser->idx = 0;
 571        }
 572
 573        /* read the non-space input */
 574        while (cnt && !isspace(ch)) {
 575                if (parser->idx < parser->size - 1)
 576                        parser->buffer[parser->idx++] = ch;
 577                else {
 578                        ret = -EINVAL;
 579                        goto out;
 580                }
 581                ret = get_user(ch, ubuf++);
 582                if (ret)
 583                        goto out;
 584                read++;
 585                cnt--;
 586        }
 587
 588        /* We either got finished input or we have to wait for another call. */
 589        if (isspace(ch)) {
 590                parser->buffer[parser->idx] = 0;
 591                parser->cont = false;
 592        } else {
 593                parser->cont = true;
 594                parser->buffer[parser->idx++] = ch;
 595        }
 596
 597        *ppos += read;
 598        ret = read;
 599
 600out:
 601        return ret;
 602}
 603
 604ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
 605{
 606        int len;
 607        int ret;
 608
 609        if (!cnt)
 610                return 0;
 611
 612        if (s->len <= s->readpos)
 613                return -EBUSY;
 614
 615        len = s->len - s->readpos;
 616        if (cnt > len)
 617                cnt = len;
 618        ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
 619        if (ret == cnt)
 620                return -EFAULT;
 621
 622        cnt -= ret;
 623
 624        s->readpos += cnt;
 625        return cnt;
 626}
 627
 628static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 629{
 630        int len;
 631
 632        if (s->len <= s->readpos)
 633                return -EBUSY;
 634
 635        len = s->len - s->readpos;
 636        if (cnt > len)
 637                cnt = len;
 638        memcpy(buf, s->buffer + s->readpos, cnt);
 639
 640        s->readpos += cnt;
 641        return cnt;
 642}
 643
 644/*
 645 * ftrace_max_lock is used to protect the swapping of buffers
 646 * when taking a max snapshot. The buffers themselves are
 647 * protected by per_cpu spinlocks. But the action of the swap
 648 * needs its own lock.
 649 *
 650 * This is defined as a arch_spinlock_t in order to help
 651 * with performance when lockdep debugging is enabled.
 652 *
 653 * It is also used in other places outside the update_max_tr
 654 * so it needs to be defined outside of the
 655 * CONFIG_TRACER_MAX_TRACE.
 656 */
 657static arch_spinlock_t ftrace_max_lock =
 658        (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 659
 660unsigned long __read_mostly     tracing_thresh;
 661
 662#ifdef CONFIG_TRACER_MAX_TRACE
 663unsigned long __read_mostly     tracing_max_latency;
 664
 665/*
 666 * Copy the new maximum trace into the separate maximum-trace
 667 * structure. (this way the maximum trace is permanently saved,
 668 * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
 669 */
 670static void
 671__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 672{
 673        struct trace_array_cpu *data = tr->data[cpu];
 674        struct trace_array_cpu *max_data;
 675
 676        max_tr.cpu = cpu;
 677        max_tr.time_start = data->preempt_timestamp;
 678
 679        max_data = max_tr.data[cpu];
 680        max_data->saved_latency = tracing_max_latency;
 681        max_data->critical_start = data->critical_start;
 682        max_data->critical_end = data->critical_end;
 683
 684        memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
 685        max_data->pid = tsk->pid;
 686        max_data->uid = task_uid(tsk);
 687        max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
 688        max_data->policy = tsk->policy;
 689        max_data->rt_priority = tsk->rt_priority;
 690
 691        /* record this tasks comm */
 692        tracing_record_cmdline(tsk);
 693}
 694
 695/**
 696 * update_max_tr - snapshot all trace buffers from global_trace to max_tr
 697 * @tr: tracer
 698 * @tsk: the task with the latency
 699 * @cpu: The cpu that initiated the trace.
 700 *
 701 * Flip the buffers between the @tr and the max_tr and record information
 702 * about which task was the cause of this latency.
 703 */
 704void
 705update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 706{
 707        struct ring_buffer *buf;
 708
 709        if (trace_stop_count)
 710                return;
 711
 712        WARN_ON_ONCE(!irqs_disabled());
 713
 714        if (!current_trace->allocated_snapshot) {
 715                /* Only the nop tracer should hit this when disabling */
 716                WARN_ON_ONCE(current_trace != &nop_trace);
 717                return;
 718        }
 719
 720        arch_spin_lock(&ftrace_max_lock);
 721
 722        buf = tr->buffer;
 723        tr->buffer = max_tr.buffer;
 724        max_tr.buffer = buf;
 725
 726        __update_max_tr(tr, tsk, cpu);
 727        arch_spin_unlock(&ftrace_max_lock);
 728}
 729
 730/**
 731 * update_max_tr_single - only copy one trace over, and reset the rest
 732 * @tr - tracer
 733 * @tsk - task with the latency
 734 * @cpu - the cpu of the buffer to copy.
 735 *
 736 * Flip the trace of a single CPU buffer between the @tr and the max_tr.
 737 */
 738void
 739update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 740{
 741        int ret;
 742
 743        if (trace_stop_count)
 744                return;
 745
 746        WARN_ON_ONCE(!irqs_disabled());
 747        if (!current_trace->allocated_snapshot) {
 748                /* Only the nop tracer should hit this when disabling */
 749                WARN_ON_ONCE(current_trace != &nop_trace);
 750                return;
 751        }
 752
 753        arch_spin_lock(&ftrace_max_lock);
 754
 755        ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
 756
 757        if (ret == -EBUSY) {
 758                /*
 759                 * We failed to swap the buffer due to a commit taking
 760                 * place on this CPU. We fail to record, but we reset
 761                 * the max trace buffer (no one writes directly to it)
 762                 * and flag that it failed.
 763                 */
 764                trace_array_printk(&max_tr, _THIS_IP_,
 765                        "Failed to swap buffers due to commit in progress\n");
 766        }
 767
 768        WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
 769
 770        __update_max_tr(tr, tsk, cpu);
 771        arch_spin_unlock(&ftrace_max_lock);
 772}
 773#endif /* CONFIG_TRACER_MAX_TRACE */
 774
 775static void default_wait_pipe(struct trace_iterator *iter)
 776{
 777        DEFINE_WAIT(wait);
 778
 779        prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
 780
 781        /*
 782         * The events can happen in critical sections where
 783         * checking a work queue can cause deadlocks.
 784         * After adding a task to the queue, this flag is set
 785         * only to notify events to try to wake up the queue
 786         * using irq_work.
 787         *
 788         * We don't clear it even if the buffer is no longer
 789         * empty. The flag only causes the next event to run
 790         * irq_work to do the work queue wake up. The worse
 791         * that can happen if we race with !trace_empty() is that
 792         * an event will cause an irq_work to try to wake up
 793         * an empty queue.
 794         *
 795         * There's no reason to protect this flag either, as
 796         * the work queue and irq_work logic will do the necessary
 797         * synchronization for the wake ups. The only thing
 798         * that is necessary is that the wake up happens after
 799         * a task has been queued. It's OK for spurious wake ups.
 800         */
 801        trace_wakeup_needed = true;
 802
 803        if (trace_empty(iter))
 804                schedule();
 805
 806        finish_wait(&trace_wait, &wait);
 807}
 808
 809/**
 810 * register_tracer - register a tracer with the ftrace system.
 811 * @type - the plugin for the tracer
 812 *
 813 * Register a new plugin tracer.
 814 */
 815int register_tracer(struct tracer *type)
 816{
 817        struct tracer *t;
 818        int ret = 0;
 819
 820        if (!type->name) {
 821                pr_info("Tracer must have a name\n");
 822                return -1;
 823        }
 824
 825        if (strlen(type->name) >= MAX_TRACER_SIZE) {
 826                pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);
 827                return -1;
 828        }
 829
 830        mutex_lock(&trace_types_lock);
 831
 832        tracing_selftest_running = true;
 833
 834        for (t = trace_types; t; t = t->next) {
 835                if (strcmp(type->name, t->name) == 0) {
 836                        /* already found */
 837                        pr_info("Tracer %s already registered\n",
 838                                type->name);
 839                        ret = -1;
 840                        goto out;
 841                }
 842        }
 843
 844        if (!type->set_flag)
 845                type->set_flag = &dummy_set_flag;
 846        if (!type->flags)
 847                type->flags = &dummy_tracer_flags;
 848        else
 849                if (!type->flags->opts)
 850                        type->flags->opts = dummy_tracer_opt;
 851        if (!type->wait_pipe)
 852                type->wait_pipe = default_wait_pipe;
 853
 854
 855#ifdef CONFIG_FTRACE_STARTUP_TEST
 856        if (type->selftest && !tracing_selftest_disabled) {
 857                struct tracer *saved_tracer = current_trace;
 858                struct trace_array *tr = &global_trace;
 859
 860                /*
 861                 * Run a selftest on this tracer.
 862                 * Here we reset the trace buffer, and set the current
 863                 * tracer to be this tracer. The tracer can then run some
 864                 * internal tracing to verify that everything is in order.
 865                 * If we fail, we do not register this tracer.
 866                 */
 867                tracing_reset_online_cpus(tr);
 868
 869                current_trace = type;
 870
 871                if (type->use_max_tr) {
 872                        /* If we expanded the buffers, make sure the max is expanded too */
 873                        if (ring_buffer_expanded)
 874                                ring_buffer_resize(max_tr.buffer, trace_buf_size,
 875                                                   RING_BUFFER_ALL_CPUS);
 876                        type->allocated_snapshot = true;
 877                }
 878
 879                /* the test is responsible for initializing and enabling */
 880                pr_info("Testing tracer %s: ", type->name);
 881                ret = type->selftest(type, tr);
 882                /* the test is responsible for resetting too */
 883                current_trace = saved_tracer;
 884                if (ret) {
 885                        printk(KERN_CONT "FAILED!\n");
 886                        /* Add the warning after printing 'FAILED' */
 887                        WARN_ON(1);
 888                        goto out;
 889                }
 890                /* Only reset on passing, to avoid touching corrupted buffers */
 891                tracing_reset_online_cpus(tr);
 892
 893                if (type->use_max_tr) {
 894                        type->allocated_snapshot = false;
 895
 896                        /* Shrink the max buffer again */
 897                        if (ring_buffer_expanded)
 898                                ring_buffer_resize(max_tr.buffer, 1,
 899                                                   RING_BUFFER_ALL_CPUS);
 900                }
 901
 902                printk(KERN_CONT "PASSED\n");
 903        }
 904#endif
 905
 906        type->next = trace_types;
 907        trace_types = type;
 908
 909 out:
 910        tracing_selftest_running = false;
 911        mutex_unlock(&trace_types_lock);
 912
 913        if (ret || !default_bootup_tracer)
 914                goto out_unlock;
 915
 916        if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
 917                goto out_unlock;
 918
 919        printk(KERN_INFO "Starting tracer '%s'\n", type->name);
 920        /* Do we want this tracer to start on bootup? */
 921        tracing_set_tracer(type->name);
 922        default_bootup_tracer = NULL;
 923        /* disable other selftests, since this will break it. */
 924        tracing_selftest_disabled = 1;
 925#ifdef CONFIG_FTRACE_STARTUP_TEST
 926        printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
 927               type->name);
 928#endif
 929
 930 out_unlock:
 931        return ret;
 932}
 933
 934void tracing_reset(struct trace_array *tr, int cpu)
 935{
 936        struct ring_buffer *buffer = tr->buffer;
 937
 938        if (!buffer)
 939                return;
 940
 941        ring_buffer_record_disable(buffer);
 942
 943        /* Make sure all commits have finished */
 944        synchronize_sched();
 945        ring_buffer_reset_cpu(buffer, cpu);
 946
 947        ring_buffer_record_enable(buffer);
 948}
 949
 950void tracing_reset_online_cpus(struct trace_array *tr)
 951{
 952        struct ring_buffer *buffer = tr->buffer;
 953        int cpu;
 954
 955        if (!buffer)
 956                return;
 957
 958        ring_buffer_record_disable(buffer);
 959
 960        /* Make sure all commits have finished */
 961        synchronize_sched();
 962
 963        tr->time_start = ftrace_now(tr->cpu);
 964
 965        for_each_online_cpu(cpu)
 966                ring_buffer_reset_cpu(buffer, cpu);
 967
 968        ring_buffer_record_enable(buffer);
 969}
 970
 971void tracing_reset_current(int cpu)
 972{
 973        tracing_reset(&global_trace, cpu);
 974}
 975
 976void tracing_reset_current_online_cpus(void)
 977{
 978        tracing_reset_online_cpus(&global_trace);
 979}
 980
 981#define SAVED_CMDLINES 128
 982#define NO_CMDLINE_MAP UINT_MAX
 983static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
 984static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
 985static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
 986static int cmdline_idx;
 987static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 988
 989/* temporary disable recording */
 990static atomic_t trace_record_cmdline_disabled __read_mostly;
 991
 992static void trace_init_cmdlines(void)
 993{
 994        memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
 995        memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
 996        cmdline_idx = 0;
 997}
 998
 999int is_tracing_stopped(void)
1000{
1001        return trace_stop_count;
1002}
1003
1004/**
1005 * ftrace_off_permanent - disable all ftrace code permanently
1006 *
1007 * This should only be called when a serious anomally has
1008 * been detected.  This will turn off the function tracing,
1009 * ring buffers, and other tracing utilites. It takes no
1010 * locks and can be called from any context.
1011 */
1012void ftrace_off_permanent(void)
1013{
1014        tracing_disabled = 1;
1015        ftrace_stop();
1016        tracing_off_permanent();
1017}
1018
1019/**
1020 * tracing_start - quick start of the tracer
1021 *
1022 * If tracing is enabled but was stopped by tracing_stop,
1023 * this will start the tracer back up.
1024 */
1025void tracing_start(void)
1026{
1027        struct ring_buffer *buffer;
1028        unsigned long flags;
1029
1030        if (tracing_disabled)
1031                return;
1032
1033        raw_spin_lock_irqsave(&tracing_start_lock, flags);
1034        if (--trace_stop_count) {
1035                if (trace_stop_count < 0) {
1036                        /* Someone screwed up their debugging */
1037                        WARN_ON_ONCE(1);
1038                        trace_stop_count = 0;
1039                }
1040                goto out;
1041        }
1042
1043        /* Prevent the buffers from switching */
1044        arch_spin_lock(&ftrace_max_lock);
1045
1046        buffer = global_trace.buffer;
1047        if (buffer)
1048                ring_buffer_record_enable(buffer);
1049
1050        buffer = max_tr.buffer;
1051        if (buffer)
1052                ring_buffer_record_enable(buffer);
1053
1054        arch_spin_unlock(&ftrace_max_lock);
1055
1056        ftrace_start();
1057 out:
1058        raw_spin_unlock_irqrestore(&tracing_start_lock, flags);
1059}
1060
1061/**
1062 * tracing_stop - quick stop of the tracer
1063 *
1064 * Light weight way to stop tracing. Use in conjunction with
1065 * tracing_start.
1066 */
1067void tracing_stop(void)
1068{
1069        struct ring_buffer *buffer;
1070        unsigned long flags;
1071
1072        ftrace_stop();
1073        raw_spin_lock_irqsave(&tracing_start_lock, flags);
1074        if (trace_stop_count++)
1075                goto out;
1076
1077        /* Prevent the buffers from switching */
1078        arch_spin_lock(&ftrace_max_lock);
1079
1080        buffer = global_trace.buffer;
1081        if (buffer)
1082                ring_buffer_record_disable(buffer);
1083
1084        buffer = max_tr.buffer;
1085        if (buffer)
1086                ring_buffer_record_disable(buffer);
1087
1088        arch_spin_unlock(&ftrace_max_lock);
1089
1090 out:
1091        raw_spin_unlock_irqrestore(&tracing_start_lock, flags);
1092}
1093
1094void trace_stop_cmdline_recording(void);
1095
1096static void trace_save_cmdline(struct task_struct *tsk)
1097{
1098        unsigned pid, idx;
1099
1100        if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
1101                return;
1102
1103        /*
1104         * It's not the end of the world if we don't get
1105         * the lock, but we also don't want to spin
1106         * nor do we want to disable interrupts,
1107         * so if we miss here, then better luck next time.
1108         */
1109        if (!arch_spin_trylock(&trace_cmdline_lock))
1110                return;
1111
1112        idx = map_pid_to_cmdline[tsk->pid];
1113        if (idx == NO_CMDLINE_MAP) {
1114                idx = (cmdline_idx + 1) % SAVED_CMDLINES;
1115
1116                /*
1117                 * Check whether the cmdline buffer at idx has a pid
1118                 * mapped. We are going to overwrite that entry so we
1119                 * need to clear the map_pid_to_cmdline. Otherwise we
1120                 * would read the new comm for the old pid.
1121                 */
1122                pid = map_cmdline_to_pid[idx];
1123                if (pid != NO_CMDLINE_MAP)
1124                        map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
1125
1126                map_cmdline_to_pid[idx] = tsk->pid;
1127                map_pid_to_cmdline[tsk->pid] = idx;
1128
1129                cmdline_idx = idx;
1130        }
1131
1132        memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
1133
1134        arch_spin_unlock(&trace_cmdline_lock);
1135}
1136
1137void trace_find_cmdline(int pid, char comm[])
1138{
1139        unsigned map;
1140
1141        if (!pid) {
1142                strcpy(comm, "<idle>");
1143                return;
1144        }
1145
1146        if (WARN_ON_ONCE(pid < 0)) {
1147                strcpy(comm, "<XXX>");
1148                return;
1149        }
1150
1151        if (pid > PID_MAX_DEFAULT) {
1152                strcpy(comm, "<...>");
1153                return;
1154        }
1155
1156        preempt_disable();
1157        arch_spin_lock(&trace_cmdline_lock);
1158        map = map_pid_to_cmdline[pid];
1159        if (map != NO_CMDLINE_MAP)
1160                strcpy(comm, saved_cmdlines[map]);
1161        else
1162                strcpy(comm, "<...>");
1163
1164        arch_spin_unlock(&trace_cmdline_lock);
1165        preempt_enable();
1166}
1167
1168void tracing_record_cmdline(struct task_struct *tsk)
1169{
1170        if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
1171                return;
1172
1173        if (!__this_cpu_read(trace_cmdline_save))
1174                return;
1175
1176        __this_cpu_write(trace_cmdline_save, false);
1177
1178        trace_save_cmdline(tsk);
1179}
1180
1181void
1182tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
1183                             int pc)
1184{
1185        struct task_struct *tsk = current;
1186
1187        entry->preempt_count            = pc & 0xff;
1188        entry->pid                      = (tsk) ? tsk->pid : 0;
1189        entry->flags =
1190#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
1191                (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
1192#else
1193                TRACE_FLAG_IRQS_NOSUPPORT |
1194#endif
1195                ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
1196                ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
1197                (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
1198}
1199EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
1200
1201struct ring_buffer_event *
1202trace_buffer_lock_reserve(struct ring_buffer *buffer,
1203                          int type,
1204                          unsigned long len,
1205                          unsigned long flags, int pc)
1206{
1207        struct ring_buffer_event *event;
1208
1209        event = ring_buffer_lock_reserve(buffer, len);
1210        if (event != NULL) {
1211                struct trace_entry *ent = ring_buffer_event_data(event);
1212
1213                tracing_generic_entry_update(ent, flags, pc);
1214                ent->type = type;
1215        }
1216
1217        return event;
1218}
1219
1220void
1221__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
1222{
1223        __this_cpu_write(trace_cmdline_save, true);
1224        if (trace_wakeup_needed) {
1225                trace_wakeup_needed = false;
1226                /* irq_work_queue() supplies it's own memory barriers */
1227                irq_work_queue(&trace_work_wakeup);
1228        }
1229        ring_buffer_unlock_commit(buffer, event);
1230}
1231
1232static inline void
1233__trace_buffer_unlock_commit(struct ring_buffer *buffer,
1234                             struct ring_buffer_event *event,
1235                             unsigned long flags, int pc)
1236{
1237        __buffer_unlock_commit(buffer, event);
1238
1239        ftrace_trace_stack(buffer, flags, 6, pc);
1240        ftrace_trace_userstack(buffer, flags, pc);
1241}
1242
1243void trace_buffer_unlock_commit(struct ring_buffer *buffer,
1244                                struct ring_buffer_event *event,
1245                                unsigned long flags, int pc)
1246{
1247        __trace_buffer_unlock_commit(buffer, event, flags, pc);
1248}
1249EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit);
1250
1251struct ring_buffer_event *
1252trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
1253                                  int type, unsigned long len,
1254                                  unsigned long flags, int pc)
1255{
1256        *current_rb = global_trace.buffer;
1257        return trace_buffer_lock_reserve(*current_rb,
1258                                         type, len, flags, pc);
1259}
1260EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);
1261
1262void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
1263                                        struct ring_buffer_event *event,
1264                                        unsigned long flags, int pc)
1265{
1266        __trace_buffer_unlock_commit(buffer, event, flags, pc);
1267}
1268EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
1269
1270void trace_buffer_unlock_commit_regs(struct ring_buffer *buffer,
1271                                     struct ring_buffer_event *event,
1272                                     unsigned long flags, int pc,
1273                                     struct pt_regs *regs)
1274{
1275        __buffer_unlock_commit(buffer, event);
1276
1277        ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
1278        ftrace_trace_userstack(buffer, flags, pc);
1279}
1280EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit_regs);
1281
1282void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
1283                                         struct ring_buffer_event *event)
1284{
1285        ring_buffer_discard_commit(buffer, event);
1286}
1287EXPORT_SYMBOL_GPL(trace_current_buffer_discard_commit);
1288
1289void
1290trace_function(struct trace_array *tr,
1291               unsigned long ip, unsigned long parent_ip, unsigned long flags,
1292               int pc)
1293{
1294        struct ftrace_event_call *call = &event_function;
1295        struct ring_buffer *buffer = tr->buffer;
1296        struct ring_buffer_event *event;
1297        struct ftrace_entry *entry;
1298
1299        /* If we are reading the ring buffer, don't trace */
1300        if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
1301                return;
1302
1303        event = trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
1304                                          flags, pc);
1305        if (!event)
1306                return;
1307        entry   = ring_buffer_event_data(event);
1308        entry->ip                       = ip;
1309        entry->parent_ip                = parent_ip;
1310
1311        if (!filter_check_discard(call, entry, buffer, event))
1312                __buffer_unlock_commit(buffer, event);
1313}
1314
1315void
1316ftrace(struct trace_array *tr, struct trace_array_cpu *data,
1317       unsigned long ip, unsigned long parent_ip, unsigned long flags,
1318       int pc)
1319{
1320        if (likely(!atomic_read(&data->disabled)))
1321                trace_function(tr, ip, parent_ip, flags, pc);
1322}
1323
1324#ifdef CONFIG_STACKTRACE
1325
1326#define FTRACE_STACK_MAX_ENTRIES (PAGE_SIZE / sizeof(unsigned long))
1327struct ftrace_stack {
1328        unsigned long           calls[FTRACE_STACK_MAX_ENTRIES];
1329};
1330
1331static DEFINE_PER_CPU(struct ftrace_stack, ftrace_stack);
1332static DEFINE_PER_CPU(int, ftrace_stack_reserve);
1333
1334static void __ftrace_trace_stack(struct ring_buffer *buffer,
1335                                 unsigned long flags,
1336                                 int skip, int pc, struct pt_regs *regs)
1337{
1338        struct ftrace_event_call *call = &event_kernel_stack;
1339        struct ring_buffer_event *event;
1340        struct stack_entry *entry;
1341        struct stack_trace trace;
1342        int use_stack;
1343        int size = FTRACE_STACK_ENTRIES;
1344
1345        trace.nr_entries        = 0;
1346        trace.skip              = skip;
1347
1348        /*
1349         * Since events can happen in NMIs there's no safe way to
1350         * use the per cpu ftrace_stacks. We reserve it and if an interrupt
1351         * or NMI comes in, it will just have to use the default
1352         * FTRACE_STACK_SIZE.
1353         */
1354        preempt_disable_notrace();
1355
1356        use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
1357        /*
1358         * We don't need any atomic variables, just a barrier.
1359         * If an interrupt comes in, we don't care, because it would
1360         * have exited and put the counter back to what we want.
1361         * We just need a barrier to keep gcc from moving things
1362         * around.
1363         */
1364        barrier();
1365        if (use_stack == 1) {
1366                trace.entries           = &__get_cpu_var(ftrace_stack).calls[0];
1367                trace.max_entries       = FTRACE_STACK_MAX_ENTRIES;
1368
1369                if (regs)
1370                        save_stack_trace_regs(regs, &trace);
1371                else
1372                        save_stack_trace(&trace);
1373
1374                if (trace.nr_entries > size)
1375                        size = trace.nr_entries;
1376        } else
1377                /* From now on, use_stack is a boolean */
1378                use_stack = 0;
1379
1380        size *= sizeof(unsigned long);
1381
1382        event = trace_buffer_lock_reserve(buffer, TRACE_STACK,
1383                                          sizeof(*entry) + size, flags, pc);
1384        if (!event)
1385                goto out;
1386        entry = ring_buffer_event_data(event);
1387
1388        memset(&entry->caller, 0, size);
1389
1390        if (use_stack)
1391                memcpy(&entry->caller, trace.entries,
1392                       trace.nr_entries * sizeof(unsigned long));
1393        else {
1394                trace.max_entries       = FTRACE_STACK_ENTRIES;
1395                trace.entries           = entry->caller;
1396                if (regs)
1397                        save_stack_trace_regs(regs, &trace);
1398                else
1399                        save_stack_trace(&trace);
1400        }
1401
1402        entry->size = trace.nr_entries;
1403
1404        if (!filter_check_discard(call, entry, buffer, event))
1405                __buffer_unlock_commit(buffer, event);
1406
1407 out:
1408        /* Again, don't let gcc optimize things here */
1409        barrier();
1410        __this_cpu_dec(ftrace_stack_reserve);
1411        preempt_enable_notrace();
1412
1413}
1414
1415void ftrace_trace_stack_regs(struct ring_buffer *buffer, unsigned long flags,
1416                             int skip, int pc, struct pt_regs *regs)
1417{
1418        if (!(trace_flags & TRACE_ITER_STACKTRACE))
1419                return;
1420
1421        __ftrace_trace_stack(buffer, flags, skip, pc, regs);
1422}
1423
1424void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
1425                        int skip, int pc)
1426{
1427        if (!(trace_flags & TRACE_ITER_STACKTRACE))
1428                return;
1429
1430        __ftrace_trace_stack(buffer, flags, skip, pc, NULL);
1431}
1432
1433void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
1434                   int pc)
1435{
1436        __ftrace_trace_stack(tr->buffer, flags, skip, pc, NULL);
1437}
1438
1439/**
1440 * trace_dump_stack - record a stack back trace in the trace buffer
1441 */
1442void trace_dump_stack(void)
1443{
1444        unsigned long flags;
1445
1446        if (tracing_disabled || tracing_selftest_running)
1447                return;
1448
1449        local_save_flags(flags);
1450
1451        /* skipping 3 traces, seems to get us at the caller of this function */
1452        __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count(), NULL);
1453}
1454
1455static DEFINE_PER_CPU(int, user_stack_count);
1456
1457void
1458ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
1459{
1460        struct ftrace_event_call *call = &event_user_stack;
1461        struct ring_buffer_event *event;
1462        struct userstack_entry *entry;
1463        struct stack_trace trace;
1464
1465        if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
1466                return;
1467
1468        /*
1469         * NMIs can not handle page faults, even with fix ups.
1470         * The save user stack can (and often does) fault.
1471         */
1472        if (unlikely(in_nmi()))
1473                return;
1474
1475        /*
1476         * prevent recursion, since the user stack tracing may
1477         * trigger other kernel events.
1478         */
1479        preempt_disable();
1480        if (__this_cpu_read(user_stack_count))
1481                goto out;
1482
1483        __this_cpu_inc(user_stack_count);
1484
1485        event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
1486                                          sizeof(*entry), flags, pc);
1487        if (!event)
1488                goto out_drop_count;
1489        entry   = ring_buffer_event_data(event);
1490
1491        entry->tgid             = current->tgid;
1492        memset(&entry->caller, 0, sizeof(entry->caller));
1493
1494        trace.nr_entries        = 0;
1495        trace.max_entries       = FTRACE_STACK_ENTRIES;
1496        trace.skip              = 0;
1497        trace.entries           = entry->caller;
1498
1499        save_stack_trace_user(&trace);
1500        if (!filter_check_discard(call, entry, buffer, event))
1501                __buffer_unlock_commit(buffer, event);
1502
1503 out_drop_count:
1504        __this_cpu_dec(user_stack_count);
1505 out:
1506        preempt_enable();
1507}
1508
1509#ifdef UNUSED
1510static void __trace_userstack(struct trace_array *tr, unsigned long flags)
1511{
1512        ftrace_trace_userstack(tr, flags, preempt_count());
1513}
1514#endif /* UNUSED */
1515
1516#endif /* CONFIG_STACKTRACE */
1517
1518/* created for use with alloc_percpu */
1519struct trace_buffer_struct {
1520        char buffer[TRACE_BUF_SIZE];
1521};
1522
1523static struct trace_buffer_struct *trace_percpu_buffer;
1524static struct trace_buffer_struct *trace_percpu_sirq_buffer;
1525static struct trace_buffer_struct *trace_percpu_irq_buffer;
1526static struct trace_buffer_struct *trace_percpu_nmi_buffer;
1527
1528/*
1529 * The buffer used is dependent on the context. There is a per cpu
1530 * buffer for normal context, softirq contex, hard irq context and
1531 * for NMI context. Thise allows for lockless recording.
1532 *
1533 * Note, if the buffers failed to be allocated, then this returns NULL
1534 */
1535static char *get_trace_buf(void)
1536{
1537        struct trace_buffer_struct *percpu_buffer;
1538
1539        /*
1540         * If we have allocated per cpu buffers, then we do not
1541         * need to do any locking.
1542         */
1543        if (in_nmi())
1544                percpu_buffer = trace_percpu_nmi_buffer;
1545        else if (in_irq())
1546                percpu_buffer = trace_percpu_irq_buffer;
1547        else if (in_softirq())
1548                percpu_buffer = trace_percpu_sirq_buffer;
1549        else
1550                percpu_buffer = trace_percpu_buffer;
1551
1552        if (!percpu_buffer)
1553                return NULL;
1554
1555        return this_cpu_ptr(&percpu_buffer->buffer[0]);
1556}
1557
1558static int alloc_percpu_trace_buffer(void)
1559{
1560        struct trace_buffer_struct *buffers;
1561        struct trace_buffer_struct *sirq_buffers;
1562        struct trace_buffer_struct *irq_buffers;
1563        struct trace_buffer_struct *nmi_buffers;
1564
1565        buffers = alloc_percpu(struct trace_buffer_struct);
1566        if (!buffers)
1567                goto err_warn;
1568
1569        sirq_buffers = alloc_percpu(struct trace_buffer_struct);
1570        if (!sirq_buffers)
1571                goto err_sirq;
1572
1573        irq_buffers = alloc_percpu(struct trace_buffer_struct);
1574        if (!irq_buffers)
1575                goto err_irq;
1576
1577        nmi_buffers = alloc_percpu(struct trace_buffer_struct);
1578        if (!nmi_buffers)
1579                goto err_nmi;
1580
1581        trace_percpu_buffer = buffers;
1582        trace_percpu_sirq_buffer = sirq_buffers;
1583        trace_percpu_irq_buffer = irq_buffers;
1584        trace_percpu_nmi_buffer = nmi_buffers;
1585
1586        return 0;
1587
1588 err_nmi:
1589        free_percpu(irq_buffers);
1590 err_irq:
1591        free_percpu(sirq_buffers);
1592 err_sirq:
1593        free_percpu(buffers);
1594 err_warn:
1595        WARN(1, "Could not allocate percpu trace_printk buffer");
1596        return -ENOMEM;
1597}
1598
1599static int buffers_allocated;
1600
1601void trace_printk_init_buffers(void)
1602{
1603        if (buffers_allocated)
1604                return;
1605
1606        if (alloc_percpu_trace_buffer())
1607                return;
1608
1609        pr_info("ftrace: Allocated trace_printk buffers\n");
1610
1611        /* Expand the buffers to set size */
1612        tracing_update_buffers();
1613
1614        buffers_allocated = 1;
1615
1616        /*
1617         * trace_printk_init_buffers() can be called by modules.
1618         * If that happens, then we need to start cmdline recording
1619         * directly here. If the global_trace.buffer is already
1620         * allocated here, then this was called by module code.
1621         */
1622        if (global_trace.buffer)
1623                tracing_start_cmdline_record();
1624}
1625
1626void trace_printk_start_comm(void)
1627{
1628        /* Start tracing comms if trace printk is set */
1629        if (!buffers_allocated)
1630                return;
1631        tracing_start_cmdline_record();
1632}
1633
1634static void trace_printk_start_stop_comm(int enabled)
1635{
1636        if (!buffers_allocated)
1637                return;
1638
1639        if (enabled)
1640                tracing_start_cmdline_record();
1641        else
1642                tracing_stop_cmdline_record();
1643}
1644
1645/**
1646 * trace_vbprintk - write binary msg to tracing buffer
1647 *
1648 */
1649int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
1650{
1651        struct ftrace_event_call *call = &event_bprint;
1652        struct ring_buffer_event *event;
1653        struct ring_buffer *buffer;
1654        struct trace_array *tr = &global_trace;
1655        struct bprint_entry *entry;
1656        unsigned long flags;
1657        char *tbuffer;
1658        int len = 0, size, pc;
1659
1660        if (unlikely(tracing_selftest_running || tracing_disabled))
1661                return 0;
1662
1663        /* Don't pollute graph traces with trace_vprintk internals */
1664        pause_graph_tracing();
1665
1666        pc = preempt_count();
1667        preempt_disable_notrace();
1668
1669        tbuffer = get_trace_buf();
1670        if (!tbuffer) {
1671                len = 0;
1672                goto out;
1673        }
1674
1675        len = vbin_printf((u32 *)tbuffer, TRACE_BUF_SIZE/sizeof(int), fmt, args);
1676
1677        if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0)
1678                goto out;
1679
1680        local_save_flags(flags);
1681        size = sizeof(*entry) + sizeof(u32) * len;
1682        buffer = tr->buffer;
1683        event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
1684                                          flags, pc);
1685        if (!event)
1686                goto out;
1687        entry = ring_buffer_event_data(event);
1688        entry->ip                       = ip;
1689        entry->fmt                      = fmt;
1690
1691        memcpy(entry->buf, tbuffer, sizeof(u32) * len);
1692        if (!filter_check_discard(call, entry, buffer, event)) {
1693                __buffer_unlock_commit(buffer, event);
1694                ftrace_trace_stack(buffer, flags, 6, pc);
1695        }
1696
1697out:
1698        preempt_enable_notrace();
1699        unpause_graph_tracing();
1700
1701        return len;
1702}
1703EXPORT_SYMBOL_GPL(trace_vbprintk);
1704
1705int trace_array_printk(struct trace_array *tr,
1706                       unsigned long ip, const char *fmt, ...)
1707{
1708        int ret;
1709        va_list ap;
1710
1711        if (!(trace_flags & TRACE_ITER_PRINTK))
1712                return 0;
1713
1714        va_start(ap, fmt);
1715        ret = trace_array_vprintk(tr, ip, fmt, ap);
1716        va_end(ap);
1717        return ret;
1718}
1719
1720int trace_array_vprintk(struct trace_array *tr,
1721                        unsigned long ip, const char *fmt, va_list args)
1722{
1723        struct ftrace_event_call *call = &event_print;
1724        struct ring_buffer_event *event;
1725        struct ring_buffer *buffer;
1726        int len = 0, size, pc;
1727        struct print_entry *entry;
1728        unsigned long flags;
1729        char *tbuffer;
1730
1731        if (tracing_disabled || tracing_selftest_running)
1732                return 0;
1733
1734        /* Don't pollute graph traces with trace_vprintk internals */
1735        pause_graph_tracing();
1736
1737        pc = preempt_count();
1738        preempt_disable_notrace();
1739
1740
1741        tbuffer = get_trace_buf();
1742        if (!tbuffer) {
1743                len = 0;
1744                goto out;
1745        }
1746
1747        len = vsnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args);
1748        if (len > TRACE_BUF_SIZE)
1749                goto out;
1750
1751        local_save_flags(flags);
1752        size = sizeof(*entry) + len + 1;
1753        buffer = tr->buffer;
1754        event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
1755                                          flags, pc);
1756        if (!event)
1757                goto out;
1758        entry = ring_buffer_event_data(event);
1759        entry->ip = ip;
1760
1761        memcpy(&entry->buf, tbuffer, len);
1762        entry->buf[len] = '\0';
1763        if (!filter_check_discard(call, entry, buffer, event)) {
1764                __buffer_unlock_commit(buffer, event);
1765                ftrace_trace_stack(buffer, flags, 6, pc);
1766        }
1767 out:
1768        preempt_enable_notrace();
1769        unpause_graph_tracing();
1770
1771        return len;
1772}
1773
1774int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
1775{
1776        return trace_array_vprintk(&global_trace, ip, fmt, args);
1777}
1778EXPORT_SYMBOL_GPL(trace_vprintk);
1779
1780static void trace_iterator_increment(struct trace_iterator *iter)
1781{
1782        struct ring_buffer_iter *buf_iter = trace_buffer_iter(iter, iter->cpu);
1783
1784        iter->idx++;
1785        if (buf_iter)
1786                ring_buffer_read(buf_iter, NULL);
1787}
1788
1789static struct trace_entry *
1790peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts,
1791                unsigned long *lost_events)
1792{
1793        struct ring_buffer_event *event;
1794        struct ring_buffer_iter *buf_iter = trace_buffer_iter(iter, cpu);
1795
1796        if (buf_iter)
1797                event = ring_buffer_iter_peek(buf_iter, ts);
1798        else
1799                event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
1800                                         lost_events);
1801
1802        if (event) {
1803                iter->ent_size = ring_buffer_event_length(event);
1804                return ring_buffer_event_data(event);
1805        }
1806        iter->ent_size = 0;
1807        return NULL;
1808}
1809
1810static struct trace_entry *
1811__find_next_entry(struct trace_iterator *iter, int *ent_cpu,
1812                  unsigned long *missing_events, u64 *ent_ts)
1813{
1814        struct ring_buffer *buffer = iter->tr->buffer;
1815        struct trace_entry *ent, *next = NULL;
1816        unsigned long lost_events = 0, next_lost = 0;
1817        int cpu_file = iter->cpu_file;
1818        u64 next_ts = 0, ts;
1819        int next_cpu = -1;
1820        int next_size = 0;
1821        int cpu;
1822
1823        /*
1824         * If we are in a per_cpu trace file, don't bother by iterating over
1825         * all cpu and peek directly.
1826         */
1827        if (cpu_file > TRACE_PIPE_ALL_CPU) {
1828                if (ring_buffer_empty_cpu(buffer, cpu_file))
1829                        return NULL;
1830                ent = peek_next_entry(iter, cpu_file, ent_ts, missing_events);
1831                if (ent_cpu)
1832                        *ent_cpu = cpu_file;
1833
1834                return ent;
1835        }
1836
1837        for_each_tracing_cpu(cpu) {
1838
1839                if (ring_buffer_empty_cpu(buffer, cpu))
1840                        continue;
1841
1842                ent = peek_next_entry(iter, cpu, &ts, &lost_events);
1843
1844                /*
1845                 * Pick the entry with the smallest timestamp:
1846                 */
1847                if (ent && (!next || ts < next_ts)) {
1848                        next = ent;
1849                        next_cpu = cpu;
1850                        next_ts = ts;
1851                        next_lost = lost_events;
1852                        next_size = iter->ent_size;
1853                }
1854        }
1855
1856        iter->ent_size = next_size;
1857
1858        if (ent_cpu)
1859                *ent_cpu = next_cpu;
1860
1861        if (ent_ts)
1862                *ent_ts = next_ts;
1863
1864        if (missing_events)
1865                *missing_events = next_lost;
1866
1867        return next;
1868}
1869
1870/* Find the next real entry, without updating the iterator itself */
1871struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
1872                                          int *ent_cpu, u64 *ent_ts)
1873{
1874        return __find_next_entry(iter, ent_cpu, NULL, ent_ts);
1875}
1876
1877/* Find the next real entry, and increment the iterator to the next entry */
1878void *trace_find_next_entry_inc(struct trace_iterator *iter)
1879{
1880        iter->ent = __find_next_entry(iter, &iter->cpu,
1881                                      &iter->lost_events, &iter->ts);
1882
1883        if (iter->ent)
1884                trace_iterator_increment(iter);
1885
1886        return iter->ent ? iter : NULL;
1887}
1888
1889static void trace_consume(struct trace_iterator *iter)
1890{
1891        ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
1892                            &iter->lost_events);
1893}
1894
1895static void *s_next(struct seq_file *m, void *v, loff_t *pos)
1896{
1897        struct trace_iterator *iter = m->private;
1898        int i = (int)*pos;
1899        void *ent;
1900
1901        WARN_ON_ONCE(iter->leftover);
1902
1903        (*pos)++;
1904
1905        /* can't go backwards */
1906        if (iter->idx > i)
1907                return NULL;
1908
1909        if (iter->idx < 0)
1910                ent = trace_find_next_entry_inc(iter);
1911        else
1912                ent = iter;
1913
1914        while (ent && iter->idx < i)
1915                ent = trace_find_next_entry_inc(iter);
1916
1917        iter->pos = *pos;
1918
1919        return ent;
1920}
1921
1922void tracing_iter_reset(struct trace_iterator *iter, int cpu)
1923{
1924        struct trace_array *tr = iter->tr;
1925        struct ring_buffer_event *event;
1926        struct ring_buffer_iter *buf_iter;
1927        unsigned long entries = 0;
1928        u64 ts;
1929
1930        tr->data[cpu]->skipped_entries = 0;
1931
1932        buf_iter = trace_buffer_iter(iter, cpu);
1933        if (!buf_iter)
1934                return;
1935
1936        ring_buffer_iter_reset(buf_iter);
1937
1938        /*
1939         * We could have the case with the max latency tracers
1940         * that a reset never took place on a cpu. This is evident
1941         * by the timestamp being before the start of the buffer.
1942         */
1943        while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
1944                if (ts >= iter->tr->time_start)
1945                        break;
1946                entries++;
1947                ring_buffer_read(buf_iter, NULL);
1948        }
1949
1950        tr->data[cpu]->skipped_entries = entries;
1951}
1952
1953/*
1954 * The current tracer is copied to avoid a global locking
1955 * all around.
1956 */
1957static void *s_start(struct seq_file *m, loff_t *pos)
1958{
1959        struct trace_iterator *iter = m->private;
1960        int cpu_file = iter->cpu_file;
1961        void *p = NULL;
1962        loff_t l = 0;
1963        int cpu;
1964
1965        /*
1966         * copy the tracer to avoid using a global lock all around.
1967         * iter->trace is a copy of current_trace, the pointer to the
1968         * name may be used instead of a strcmp(), as iter->trace->name
1969         * will point to the same string as current_trace->name.
1970         */
1971        mutex_lock(&trace_types_lock);
1972        if (unlikely(current_trace && iter->trace->name != current_trace->name))
1973                *iter->trace = *current_trace;
1974        mutex_unlock(&trace_types_lock);
1975
1976        if (iter->snapshot && iter->trace->use_max_tr)
1977                return ERR_PTR(-EBUSY);
1978
1979        if (!iter->snapshot)
1980                atomic_inc(&trace_record_cmdline_disabled);
1981
1982        if (*pos != iter->pos) {
1983                iter->ent = NULL;
1984                iter->cpu = 0;
1985                iter->idx = -1;
1986
1987                if (cpu_file == TRACE_PIPE_ALL_CPU) {
1988                        for_each_tracing_cpu(cpu)
1989                                tracing_iter_reset(iter, cpu);
1990                } else
1991                        tracing_iter_reset(iter, cpu_file);
1992
1993                iter->leftover = 0;
1994                for (p = iter; p && l < *pos; p = s_next(m, p, &l))
1995                        ;
1996
1997        } else {
1998                /*
1999                 * If we overflowed the seq_file before, then we want
2000                 * to just reuse the trace_seq buffer again.
2001                 */
2002                if (iter->leftover)
2003                        p = iter;
2004                else {
2005                        l = *pos - 1;
2006                        p = s_next(m, p, &l);
2007                }
2008        }
2009
2010        trace_event_read_lock();
2011        trace_access_lock(cpu_file);
2012        return p;
2013}
2014
2015static void s_stop(struct seq_file *m, void *p)
2016{
2017        struct trace_iterator *iter = m->private;
2018
2019        if (iter->snapshot && iter->trace->use_max_tr)
2020                return;
2021
2022        if (!iter->snapshot)
2023                atomic_dec(&trace_record_cmdline_disabled);
2024        trace_access_unlock(iter->cpu_file);
2025        trace_event_read_unlock();
2026}
2027
2028static void
2029get_total_entries(struct trace_array *tr, unsigned long *total, unsigned long *entries)
2030{
2031        unsigned long count;
2032        int cpu;
2033
2034        *total = 0;
2035        *entries = 0;
2036
2037        for_each_tracing_cpu(cpu) {
2038                count = ring_buffer_entries_cpu(tr->buffer, cpu);
2039                /*
2040                 * If this buffer has skipped entries, then we hold all
2041                 * entries for the trace and we need to ignore the
2042                 * ones before the time stamp.
2043                 */
2044                if (tr->data[cpu]->skipped_entries) {
2045                        count -= tr->data[cpu]->skipped_entries;
2046                        /* total is the same as the entries */
2047                        *total += count;
2048                } else
2049                        *total += count +
2050                                ring_buffer_overrun_cpu(tr->buffer, cpu);
2051                *entries += count;
2052        }
2053}
2054
2055static void print_lat_help_header(struct seq_file *m)
2056{
2057        seq_puts(m, "#                  _------=> CPU#            \n");
2058        seq_puts(m, "#                 / _-----=> irqs-off        \n");
2059        seq_puts(m, "#                | / _----=> need-resched    \n");
2060        seq_puts(m, "#                || / _---=> hardirq/softirq \n");
2061        seq_puts(m, "#                ||| / _--=> preempt-depth   \n");
2062        seq_puts(m, "#                |||| /     delay             \n");
2063        seq_puts(m, "#  cmd     pid   ||||| time  |   caller      \n");
2064        seq_puts(m, "#     \\   /      |||||  \\    |   /           \n");
2065}
2066
2067static void print_event_info(struct trace_array *tr, struct seq_file *m)
2068{
2069        unsigned long total;
2070        unsigned long entries;
2071
2072        get_total_entries(tr, &total, &entries);
2073        seq_printf(m, "# entries-in-buffer/entries-written: %lu/%lu   #P:%d\n",
2074                   entries, total, num_online_cpus());
2075        seq_puts(m, "#\n");
2076}
2077
2078static void print_func_help_header(struct trace_array *tr, struct seq_file *m)
2079{
2080        print_event_info(tr, m);
2081        seq_puts(m, "#           TASK-PID   CPU#      TIMESTAMP  FUNCTION\n");
2082        seq_puts(m, "#              | |       |          |         |\n");
2083}
2084
2085static void print_func_help_header_irq(struct trace_array *tr, struct seq_file *m)
2086{
2087        print_event_info(tr, m);
2088        seq_puts(m, "#                              _-----=> irqs-off\n");
2089        seq_puts(m, "#                             / _----=> need-resched\n");
2090        seq_puts(m, "#                            | / _---=> hardirq/softirq\n");
2091        seq_puts(m, "#                            || / _--=> preempt-depth\n");
2092        seq_puts(m, "#                            ||| /     delay\n");
2093        seq_puts(m, "#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION\n");
2094        seq_puts(m, "#              | |       |   ||||       |         |\n");
2095}
2096
2097void
2098print_trace_header(struct seq_file *m, struct trace_iterator *iter)
2099{
2100        unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
2101        struct trace_array *tr = iter->tr;
2102        struct trace_array_cpu *data = tr->data[tr->cpu];
2103        struct tracer *type = current_trace;
2104        unsigned long entries;
2105        unsigned long total;
2106        const char *name = "preemption";
2107
2108        name = type->name;
2109
2110        get_total_entries(tr, &total, &entries);
2111
2112        seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
2113                   name, UTS_RELEASE);
2114        seq_puts(m, "# -----------------------------------"
2115                 "---------------------------------\n");
2116        seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
2117                   " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
2118                   nsecs_to_usecs(data->saved_latency),
2119                   entries,
2120                   total,
2121                   tr->cpu,
2122#if defined(CONFIG_PREEMPT_NONE)
2123                   "server",
2124#elif defined(CONFIG_PREEMPT_VOLUNTARY)
2125                   "desktop",
2126#elif defined(CONFIG_PREEMPT)
2127                   "preempt",
2128#else
2129                   "unknown",
2130#endif
2131                   /* These are reserved for later use */
2132                   0, 0, 0, 0);
2133#ifdef CONFIG_SMP
2134        seq_printf(m, " #P:%d)\n", num_online_cpus());
2135#else
2136        seq_puts(m, ")\n");
2137#endif
2138        seq_puts(m, "#    -----------------\n");
2139        seq_printf(m, "#    | task: %.16s-%d "
2140                   "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
2141                   data->comm, data->pid,
2142                   from_kuid_munged(seq_user_ns(m), data->uid), data->nice,
2143                   data->policy, data->rt_priority);
2144        seq_puts(m, "#    -----------------\n");
2145
2146        if (data->critical_start) {
2147                seq_puts(m, "#  => started at: ");
2148                seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
2149                trace_print_seq(m, &iter->seq);
2150                seq_puts(m, "\n#  => ended at:   ");
2151                seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
2152                trace_print_seq(m, &iter->seq);
2153                seq_puts(m, "\n#\n");
2154        }
2155
2156        seq_puts(m, "#\n");
2157}
2158
2159static void test_cpu_buff_start(struct trace_iterator *iter)
2160{
2161        struct trace_seq *s = &iter->seq;
2162
2163        if (!(trace_flags & TRACE_ITER_ANNOTATE))
2164                return;
2165
2166        if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
2167                return;
2168
2169        if (cpumask_test_cpu(iter->cpu, iter->started))
2170                return;
2171
2172        if (iter->tr->data[iter->cpu]->skipped_entries)
2173                return;
2174
2175        cpumask_set_cpu(iter->cpu, iter->started);
2176
2177        /* Don't print started cpu buffer for the first entry of the trace */
2178        if (iter->idx > 1)
2179                trace_seq_printf(s, "##### CPU %u buffer started ####\n",
2180                                iter->cpu);
2181}
2182
2183static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
2184{
2185        struct trace_seq *s = &iter->seq;
2186        unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
2187        struct trace_entry *entry;
2188        struct trace_event *event;
2189
2190        entry = iter->ent;
2191
2192        test_cpu_buff_start(iter);
2193
2194        event = ftrace_find_event(entry->type);
2195
2196        if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2197                if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
2198                        if (!trace_print_lat_context(iter))
2199                                goto partial;
2200                } else {
2201                        if (!trace_print_context(iter))
2202                                goto partial;
2203                }
2204        }
2205
2206        if (event)
2207                return event->funcs->trace(iter, sym_flags, event);
2208
2209        if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
2210                goto partial;
2211
2212        return TRACE_TYPE_HANDLED;
2213partial:
2214        return TRACE_TYPE_PARTIAL_LINE;
2215}
2216
2217static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
2218{
2219        struct trace_seq *s = &iter->seq;
2220        struct trace_entry *entry;
2221        struct trace_event *event;
2222
2223        entry = iter->ent;
2224
2225        if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2226                if (!trace_seq_printf(s, "%d %d %llu ",
2227                                      entry->pid, iter->cpu, iter->ts))
2228                        goto partial;
2229        }
2230
2231        event = ftrace_find_event(entry->type);
2232        if (event)
2233                return event->funcs->raw(iter, 0, event);
2234
2235        if (!trace_seq_printf(s, "%d ?\n", entry->type))
2236                goto partial;
2237
2238        return TRACE_TYPE_HANDLED;
2239partial:
2240        return TRACE_TYPE_PARTIAL_LINE;
2241}
2242
2243static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
2244{
2245        struct trace_seq *s = &iter->seq;
2246        unsigned char newline = '\n';
2247        struct trace_entry *entry;
2248        struct trace_event *event;
2249
2250        entry = iter->ent;
2251
2252        if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2253                SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
2254                SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
2255                SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
2256        }
2257
2258        event = ftrace_find_event(entry->type);
2259        if (event) {
2260                enum print_line_t ret = event->funcs->hex(iter, 0, event);
2261                if (ret != TRACE_TYPE_HANDLED)
2262                        return ret;
2263        }
2264
2265        SEQ_PUT_FIELD_RET(s, newline);
2266
2267        return TRACE_TYPE_HANDLED;
2268}
2269
2270static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
2271{
2272        struct trace_seq *s = &iter->seq;
2273        struct trace_entry *entry;
2274        struct trace_event *event;
2275
2276        entry = iter->ent;
2277
2278        if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2279                SEQ_PUT_FIELD_RET(s, entry->pid);
2280                SEQ_PUT_FIELD_RET(s, iter->cpu);
2281                SEQ_PUT_FIELD_RET(s, iter->ts);
2282        }
2283
2284        event = ftrace_find_event(entry->type);
2285        return event ? event->funcs->binary(iter, 0, event) :
2286                TRACE_TYPE_HANDLED;
2287}
2288
2289int trace_empty(struct trace_iterator *iter)
2290{
2291        struct ring_buffer_iter *buf_iter;
2292        int cpu;
2293
2294        /* If we are looking at one CPU buffer, only check that one */
2295        if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
2296                cpu = iter->cpu_file;
2297                buf_iter = trace_buffer_iter(iter, cpu);
2298                if (buf_iter) {
2299                        if (!ring_buffer_iter_empty(buf_iter))
2300                                return 0;
2301                } else {
2302                        if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
2303                                return 0;
2304                }
2305                return 1;
2306        }
2307
2308        for_each_tracing_cpu(cpu) {
2309                buf_iter = trace_buffer_iter(iter, cpu);
2310                if (buf_iter) {
2311                        if (!ring_buffer_iter_empty(buf_iter))
2312                                return 0;
2313                } else {
2314                        if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
2315                                return 0;
2316                }
2317        }
2318
2319        return 1;
2320}
2321
2322/*  Called with trace_event_read_lock() held. */
2323enum print_line_t print_trace_line(struct trace_iterator *iter)
2324{
2325        enum print_line_t ret;
2326
2327        if (iter->lost_events &&
2328            !trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
2329                                 iter->cpu, iter->lost_events))
2330                return TRACE_TYPE_PARTIAL_LINE;
2331
2332        if (iter->trace && iter->trace->print_line) {
2333                ret = iter->trace->print_line(iter);
2334                if (ret != TRACE_TYPE_UNHANDLED)
2335                        return ret;
2336        }
2337
2338        if (iter->ent->type == TRACE_BPRINT &&
2339                        trace_flags & TRACE_ITER_PRINTK &&
2340                        trace_flags & TRACE_ITER_PRINTK_MSGONLY)
2341                return trace_print_bprintk_msg_only(iter);
2342
2343        if (iter->ent->type == TRACE_PRINT &&
2344                        trace_flags & TRACE_ITER_PRINTK &&
2345                        trace_flags & TRACE_ITER_PRINTK_MSGONLY)
2346                return trace_print_printk_msg_only(iter);
2347
2348        if (trace_flags & TRACE_ITER_BIN)
2349                return print_bin_fmt(iter);
2350
2351        if (trace_flags & TRACE_ITER_HEX)
2352                return print_hex_fmt(iter);
2353
2354        if (trace_flags & TRACE_ITER_RAW)
2355                return print_raw_fmt(iter);
2356
2357        return print_trace_fmt(iter);
2358}
2359
2360void trace_latency_header(struct seq_file *m)
2361{
2362        struct trace_iterator *iter = m->private;
2363
2364        /* print nothing if the buffers are empty */
2365        if (trace_empty(iter))
2366                return;
2367
2368        if (iter->iter_flags & TRACE_FILE_LAT_FMT)
2369                print_trace_header(m, iter);
2370
2371        if (!(trace_flags & TRACE_ITER_VERBOSE))
2372                print_lat_help_header(m);
2373}
2374
2375void trace_default_header(struct seq_file *m)
2376{
2377        struct trace_iterator *iter = m->private;
2378
2379        if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
2380                return;
2381
2382        if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
2383                /* print nothing if the buffers are empty */
2384                if (trace_empty(iter))
2385                        return;
2386                print_trace_header(m, iter);
2387                if (!(trace_flags & TRACE_ITER_VERBOSE))
2388                        print_lat_help_header(m);
2389        } else {
2390                if (!(trace_flags & TRACE_ITER_VERBOSE)) {
2391                        if (trace_flags & TRACE_ITER_IRQ_INFO)
2392                                print_func_help_header_irq(iter->tr, m);
2393                        else
2394                                print_func_help_header(iter->tr, m);
2395                }
2396        }
2397}
2398
2399static void test_ftrace_alive(struct seq_file *m)
2400{
2401        if (!ftrace_is_dead())
2402                return;
2403        seq_printf(m, "# WARNING: FUNCTION TRACING IS CORRUPTED\n");
2404        seq_printf(m, "#          MAY BE MISSING FUNCTION EVENTS\n");
2405}
2406
2407#ifdef CONFIG_TRACER_MAX_TRACE
2408static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
2409{
2410        if (iter->trace->allocated_snapshot)
2411                seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
2412        else
2413                seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
2414
2415        seq_printf(m, "# Snapshot commands:\n");
2416        seq_printf(m, "# echo 0 > snapshot : Clears and frees snapshot buffer\n");
2417        seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n");
2418        seq_printf(m, "#                      Takes a snapshot of the main buffer.\n");
2419        seq_printf(m, "# echo 2 > snapshot : Clears snapshot buffer (but does not allocate)\n");
2420        seq_printf(m, "#                      (Doesn't have to be '2' works with any number that\n");
2421        seq_printf(m, "#                       is not a '0' or '1')\n");
2422}
2423#else
2424/* Should never be called */
2425static inline void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter) { }
2426#endif
2427
2428static int s_show(struct seq_file *m, void *v)
2429{
2430        struct trace_iterator *iter = v;
2431        int ret;
2432
2433        if (iter->ent == NULL) {
2434                if (iter->tr) {
2435                        seq_printf(m, "# tracer: %s\n", iter->trace->name);
2436                        seq_puts(m, "#\n");
2437                        test_ftrace_alive(m);
2438                }
2439                if (iter->snapshot && trace_empty(iter))
2440                        print_snapshot_help(m, iter);
2441                else if (iter->trace && iter->trace->print_header)
2442                        iter->trace->print_header(m);
2443                else
2444                        trace_default_header(m);
2445
2446        } else if (iter->leftover) {
2447                /*
2448                 * If we filled the seq_file buffer earlier, we
2449                 * want to just show it now.
2450                 */
2451                ret = trace_print_seq(m, &iter->seq);
2452
2453                /* ret should this time be zero, but you never know */
2454                iter->leftover = ret;
2455
2456        } else {
2457                print_trace_line(iter);
2458                ret = trace_print_seq(m, &iter->seq);
2459                /*
2460                 * If we overflow the seq_file buffer, then it will
2461                 * ask us for this data again at start up.
2462                 * Use that instead.
2463                 *  ret is 0 if seq_file write succeeded.
2464                 *        -1 otherwise.
2465                 */
2466                iter->leftover = ret;
2467        }
2468
2469        return 0;
2470}
2471
2472static const struct seq_operations tracer_seq_ops = {
2473        .start          = s_start,
2474        .next           = s_next,
2475        .stop           = s_stop,
2476        .show           = s_show,
2477};
2478
2479static struct trace_iterator *
2480__tracing_open(struct inode *inode, struct file *file, bool snapshot)
2481{
2482        long cpu_file = (long) inode->i_private;
2483        struct trace_iterator *iter;
2484        int cpu;
2485
2486        if (tracing_disabled)
2487                return ERR_PTR(-ENODEV);
2488
2489        iter = __seq_open_private(file, &tracer_seq_ops, sizeof(*iter));
2490        if (!iter)
2491                return ERR_PTR(-ENOMEM);
2492
2493        iter->buffer_iter = kzalloc(sizeof(*iter->buffer_iter) * num_possible_cpus(),
2494                                    GFP_KERNEL);
2495        if (!iter->buffer_iter)
2496                goto release;
2497
2498        /*
2499         * We make a copy of the current tracer to avoid concurrent
2500         * changes on it while we are reading.
2501         */
2502        mutex_lock(&trace_types_lock);
2503        iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
2504        if (!iter->trace)
2505                goto fail;
2506
2507        *iter->trace = *current_trace;
2508
2509        if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
2510                goto fail;
2511
2512        if (current_trace->print_max || snapshot)
2513                iter->tr = &max_tr;
2514        else
2515                iter->tr = &global_trace;
2516        iter->snapshot = snapshot;
2517        iter->pos = -1;
2518        mutex_init(&iter->mutex);
2519        iter->cpu_file = cpu_file;
2520
2521        /* Notify the tracer early; before we stop tracing. */
2522        if (iter->trace && iter->trace->open)
2523                iter->trace->open(iter);
2524
2525        /* Annotate start of buffers if we had overruns */
2526        if (ring_buffer_overruns(iter->tr->buffer))
2527                iter->iter_flags |= TRACE_FILE_ANNOTATE;
2528
2529        /* Output in nanoseconds only if we are using a clock in nanoseconds. */
2530        if (trace_clocks[trace_clock_id].in_ns)
2531                iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
2532
2533        /* stop the trace while dumping if we are not opening "snapshot" */
2534        if (!iter->snapshot)
2535                tracing_stop();
2536
2537        if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
2538                for_each_tracing_cpu(cpu) {
2539                        iter->buffer_iter[cpu] =
2540                                ring_buffer_read_prepare(iter->tr->buffer, cpu);
2541                }
2542                ring_buffer_read_prepare_sync();
2543                for_each_tracing_cpu(cpu) {
2544                        ring_buffer_read_start(iter->buffer_iter[cpu]);
2545                        tracing_iter_reset(iter, cpu);
2546                }
2547        } else {
2548                cpu = iter->cpu_file;
2549                iter->buffer_iter[cpu] =
2550                        ring_buffer_read_prepare(iter->tr->buffer, cpu);
2551                ring_buffer_read_prepare_sync();
2552                ring_buffer_read_start(iter->buffer_iter[cpu]);
2553                tracing_iter_reset(iter, cpu);
2554        }
2555
2556        mutex_unlock(&trace_types_lock);
2557
2558        return iter;
2559
2560 fail:
2561        mutex_unlock(&trace_types_lock);
2562        kfree(iter->trace);
2563        kfree(iter->buffer_iter);
2564release:
2565        seq_release_private(inode, file);
2566        return ERR_PTR(-ENOMEM);
2567}
2568
2569int tracing_open_generic(struct inode *inode, struct file *filp)
2570{
2571        if (tracing_disabled)
2572                return -ENODEV;
2573
2574        filp->private_data = inode->i_private;
2575        return 0;
2576}
2577
2578static int tracing_release(struct inode *inode, struct file *file)
2579{
2580        struct seq_file *m = file->private_data;
2581        struct trace_iterator *iter;
2582        int cpu;
2583
2584        if (!(file->f_mode & FMODE_READ))
2585                return 0;
2586
2587        iter = m->private;
2588
2589        mutex_lock(&trace_types_lock);
2590        for_each_tracing_cpu(cpu) {
2591                if (iter->buffer_iter[cpu])
2592                        ring_buffer_read_finish(iter->buffer_iter[cpu]);
2593        }
2594
2595        if (iter->trace && iter->trace->close)
2596                iter->trace->close(iter);
2597
2598        if (!iter->snapshot)
2599                /* reenable tracing if it was previously enabled */
2600                tracing_start();
2601        mutex_unlock(&trace_types_lock);
2602
2603        mutex_destroy(&iter->mutex);
2604        free_cpumask_var(iter->started);
2605        kfree(iter->trace);
2606        kfree(iter->buffer_iter);
2607        seq_release_private(inode, file);
2608        return 0;
2609}
2610
2611static int tracing_open(struct inode *inode, struct file *file)
2612{
2613        struct trace_iterator *iter;
2614        int ret = 0;
2615
2616        /* If this file was open for write, then erase contents */
2617        if ((file->f_mode & FMODE_WRITE) &&
2618            (file->f_flags & O_TRUNC)) {
2619                long cpu = (long) inode->i_private;
2620
2621                if (cpu == TRACE_PIPE_ALL_CPU)
2622                        tracing_reset_online_cpus(&global_trace);
2623                else
2624                        tracing_reset(&global_trace, cpu);
2625        }
2626
2627        if (file->f_mode & FMODE_READ) {
2628                iter = __tracing_open(inode, file, false);
2629                if (IS_ERR(iter))
2630                        ret = PTR_ERR(iter);
2631                else if (trace_flags & TRACE_ITER_LATENCY_FMT)
2632                        iter->iter_flags |= TRACE_FILE_LAT_FMT;
2633        }
2634        return ret;
2635}
2636
2637static void *
2638t_next(struct seq_file *m, void *v, loff_t *pos)
2639{
2640        struct tracer *t = v;
2641
2642        (*pos)++;
2643
2644        if (t)
2645                t = t->next;
2646
2647        return t;
2648}
2649
2650static void *t_start(struct seq_file *m, loff_t *pos)
2651{
2652        struct tracer *t;
2653        loff_t l = 0;
2654
2655        mutex_lock(&trace_types_lock);
2656        for (t = trace_types; t && l < *pos; t = t_next(m, t, &l))
2657                ;
2658
2659        return t;
2660}
2661
2662static void t_stop(struct seq_file *m, void *p)
2663{
2664        mutex_unlock(&trace_types_lock);
2665}
2666
2667static int t_show(struct seq_file *m, void *v)
2668{
2669        struct tracer *t = v;
2670
2671        if (!t)
2672                return 0;
2673
2674        seq_printf(m, "%s", t->name);
2675        if (t->next)
2676                seq_putc(m, ' ');
2677        else
2678                seq_putc(m, '\n');
2679
2680        return 0;
2681}
2682
2683static const struct seq_operations show_traces_seq_ops = {
2684        .start          = t_start,
2685        .next           = t_next,
2686        .stop           = t_stop,
2687        .show           = t_show,
2688};
2689
2690static int show_traces_open(struct inode *inode, struct file *file)
2691{
2692        if (tracing_disabled)
2693                return -ENODEV;
2694
2695        return seq_open(file, &show_traces_seq_ops);
2696}
2697
2698static ssize_t
2699tracing_write_stub(struct file *filp, const char __user *ubuf,
2700                   size_t count, loff_t *ppos)
2701{
2702        return count;
2703}
2704
2705static loff_t tracing_seek(struct file *file, loff_t offset, int origin)
2706{
2707        if (file->f_mode & FMODE_READ)
2708                return seq_lseek(file, offset, origin);
2709        else
2710                return 0;
2711}
2712
2713static const struct file_operations tracing_fops = {
2714        .open           = tracing_open,
2715        .read           = seq_read,
2716        .write          = tracing_write_stub,
2717        .llseek         = tracing_seek,
2718        .release        = tracing_release,
2719};
2720
2721static const struct file_operations show_traces_fops = {
2722        .open           = show_traces_open,
2723        .read           = seq_read,
2724        .release        = seq_release,
2725        .llseek         = seq_lseek,
2726};
2727
2728/*
2729 * Only trace on a CPU if the bitmask is set:
2730 */
2731static cpumask_var_t tracing_cpumask;
2732
2733/*
2734 * The tracer itself will not take this lock, but still we want
2735 * to provide a consistent cpumask to user-space:
2736 */
2737static DEFINE_MUTEX(tracing_cpumask_update_lock);
2738
2739/*
2740 * Temporary storage for the character representation of the
2741 * CPU bitmask (and one more byte for the newline):
2742 */
2743static char mask_str[NR_CPUS + 1];
2744
2745static ssize_t
2746tracing_cpumask_read(struct file *filp, char __user *ubuf,
2747                     size_t count, loff_t *ppos)
2748{
2749        int len;
2750
2751        mutex_lock(&tracing_cpumask_update_lock);
2752
2753        len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
2754        if (count - len < 2) {
2755                count = -EINVAL;
2756                goto out_err;
2757        }
2758        len += sprintf(mask_str + len, "\n");
2759        count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
2760
2761out_err:
2762        mutex_unlock(&tracing_cpumask_update_lock);
2763
2764        return count;
2765}
2766
2767static ssize_t
2768tracing_cpumask_write(struct file *filp, const char __user *ubuf,
2769                      size_t count, loff_t *ppos)
2770{
2771        int err, cpu;
2772        cpumask_var_t tracing_cpumask_new;
2773
2774        if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
2775                return -ENOMEM;
2776
2777        err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
2778        if (err)
2779                goto err_unlock;
2780
2781        mutex_lock(&tracing_cpumask_update_lock);
2782
2783        local_irq_disable();
2784        arch_spin_lock(&ftrace_max_lock);
2785        for_each_tracing_cpu(cpu) {
2786                /*
2787                 * Increase/decrease the disabled counter if we are
2788                 * about to flip a bit in the cpumask:
2789                 */
2790                if (cpumask_test_cpu(cpu, tracing_cpumask) &&
2791                                !cpumask_test_cpu(cpu, tracing_cpumask_new)) {
2792                        atomic_inc(&global_trace.data[cpu]->disabled);
2793                        ring_buffer_record_disable_cpu(global_trace.buffer, cpu);
2794                }
2795                if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
2796                                cpumask_test_cpu(cpu, tracing_cpumask_new)) {
2797                        atomic_dec(&global_trace.data[cpu]->disabled);
2798                        ring_buffer_record_enable_cpu(global_trace.buffer, cpu);
2799                }
2800        }
2801        arch_spin_unlock(&ftrace_max_lock);
2802        local_irq_enable();
2803
2804        cpumask_copy(tracing_cpumask, tracing_cpumask_new);
2805
2806        mutex_unlock(&tracing_cpumask_update_lock);
2807        free_cpumask_var(tracing_cpumask_new);
2808
2809        return count;
2810
2811err_unlock:
2812        free_cpumask_var(tracing_cpumask_new);
2813
2814        return err;
2815}
2816
2817static const struct file_operations tracing_cpumask_fops = {
2818        .open           = tracing_open_generic,
2819        .read           = tracing_cpumask_read,
2820        .write          = tracing_cpumask_write,
2821        .llseek         = generic_file_llseek,
2822};
2823
2824static int tracing_trace_options_show(struct seq_file *m, void *v)
2825{
2826        struct tracer_opt *trace_opts;
2827        u32 tracer_flags;
2828        int i;
2829
2830        mutex_lock(&trace_types_lock);
2831        tracer_flags = current_trace->flags->val;
2832        trace_opts = current_trace->flags->opts;
2833
2834        for (i = 0; trace_options[i]; i++) {
2835                if (trace_flags & (1 << i))
2836                        seq_printf(m, "%s\n", trace_options[i]);
2837                else
2838                        seq_printf(m, "no%s\n", trace_options[i]);
2839        }
2840
2841        for (i = 0; trace_opts[i].name; i++) {
2842                if (tracer_flags & trace_opts[i].bit)
2843                        seq_printf(m, "%s\n", trace_opts[i].name);
2844                else
2845                        seq_printf(m, "no%s\n", trace_opts[i].name);
2846        }
2847        mutex_unlock(&trace_types_lock);
2848
2849        return 0;
2850}
2851
2852static int __set_tracer_option(struct tracer *trace,
2853                               struct tracer_flags *tracer_flags,
2854                               struct tracer_opt *opts, int neg)
2855{
2856        int ret;
2857
2858        ret = trace->set_flag(tracer_flags->val, opts->bit, !neg);
2859        if (ret)
2860                return ret;
2861
2862        if (neg)
2863                tracer_flags->val &= ~opts->bit;
2864        else
2865                tracer_flags->val |= opts->bit;
2866        return 0;
2867}
2868
2869/* Try to assign a tracer specific option */
2870static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
2871{
2872        struct tracer_flags *tracer_flags = trace->flags;
2873        struct tracer_opt *opts = NULL;
2874        int i;
2875
2876        for (i = 0; tracer_flags->opts[i].name; i++) {
2877                opts = &tracer_flags->opts[i];
2878
2879                if (strcmp(cmp, opts->name) == 0)
2880                        return __set_tracer_option(trace, trace->flags,
2881                                                   opts, neg);
2882        }
2883
2884        return -EINVAL;
2885}
2886
2887/* Some tracers require overwrite to stay enabled */
2888int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set)
2889{
2890        if (tracer->enabled && (mask & TRACE_ITER_OVERWRITE) && !set)
2891                return -1;
2892
2893        return 0;
2894}
2895
2896int set_tracer_flag(unsigned int mask, int enabled)
2897{
2898        /* do nothing if flag is already set */
2899        if (!!(trace_flags & mask) == !!enabled)
2900                return 0;
2901
2902        /* Give the tracer a chance to approve the change */
2903        if (current_trace->flag_changed)
2904                if (current_trace->flag_changed(current_trace, mask, !!enabled))
2905                        return -EINVAL;
2906
2907        if (enabled)
2908                trace_flags |= mask;
2909        else
2910                trace_flags &= ~mask;
2911
2912        if (mask == TRACE_ITER_RECORD_CMD)
2913                trace_event_enable_cmd_record(enabled);
2914
2915        if (mask == TRACE_ITER_OVERWRITE) {
2916                ring_buffer_change_overwrite(global_trace.buffer, enabled);
2917#ifdef CONFIG_TRACER_MAX_TRACE
2918                ring_buffer_change_overwrite(max_tr.buffer, enabled);
2919#endif
2920        }
2921
2922        if (mask == TRACE_ITER_PRINTK)
2923                trace_printk_start_stop_comm(enabled);
2924
2925        return 0;
2926}
2927
2928static int trace_set_options(char *option)
2929{
2930        char *cmp;
2931        int neg = 0;
2932        int ret = -ENODEV;
2933        int i;
2934
2935        cmp = strstrip(option);
2936
2937        if (strncmp(cmp, "no", 2) == 0) {
2938                neg = 1;
2939                cmp += 2;
2940        }
2941
2942        mutex_lock(&trace_types_lock);
2943
2944        for (i = 0; trace_options[i]; i++) {
2945                if (strcmp(cmp, trace_options[i]) == 0) {
2946                        ret = set_tracer_flag(1 << i, !neg);
2947                        break;
2948                }
2949        }
2950
2951        /* If no option could be set, test the specific tracer options */
2952        if (!trace_options[i])
2953                ret = set_tracer_option(current_trace, cmp, neg);
2954
2955        mutex_unlock(&trace_types_lock);
2956
2957        return ret;
2958}
2959
2960static ssize_t
2961tracing_trace_options_write(struct file *filp, const char __user *ubuf,
2962                        size_t cnt, loff_t *ppos)
2963{
2964        char buf[64];
2965        int ret;
2966
2967        if (cnt >= sizeof(buf))
2968                return -EINVAL;
2969
2970        if (copy_from_user(&buf, ubuf, cnt))
2971                return -EFAULT;
2972
2973        buf[cnt] = 0;
2974
2975        ret = trace_set_options(buf);
2976        if (ret < 0)
2977                return ret;
2978
2979        *ppos += cnt;
2980
2981        return cnt;
2982}
2983
2984static int tracing_trace_options_open(struct inode *inode, struct file *file)
2985{
2986        if (tracing_disabled)
2987                return -ENODEV;
2988        return single_open(file, tracing_trace_options_show, NULL);
2989}
2990
2991static const struct file_operations tracing_iter_fops = {
2992        .open           = tracing_trace_options_open,
2993        .read           = seq_read,
2994        .llseek         = seq_lseek,
2995        .release        = single_release,
2996        .write          = tracing_trace_options_write,
2997};
2998
2999static const char readme_msg[] =
3000        "tracing mini-HOWTO:\n\n"
3001        "# mount -t debugfs nodev /sys/kernel/debug\n\n"
3002        "# cat /sys/kernel/debug/tracing/available_tracers\n"
3003        "wakeup wakeup_rt preemptirqsoff preemptoff irqsoff function nop\n\n"
3004        "# cat /sys/kernel/debug/tracing/current_tracer\n"
3005        "nop\n"
3006        "# echo wakeup > /sys/kernel/debug/tracing/current_tracer\n"
3007        "# cat /sys/kernel/debug/tracing/current_tracer\n"
3008        "wakeup\n"
3009        "# cat /sys/kernel/debug/tracing/trace_options\n"
3010        "noprint-parent nosym-offset nosym-addr noverbose\n"
3011        "# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
3012        "# echo 1 > /sys/kernel/debug/tracing/tracing_on\n"
3013        "# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
3014        "# echo 0 > /sys/kernel/debug/tracing/tracing_on\n"
3015;
3016
3017static ssize_t
3018tracing_readme_read(struct file *filp, char __user *ubuf,
3019                       size_t cnt, loff_t *ppos)
3020{
3021        return simple_read_from_buffer(ubuf, cnt, ppos,
3022                                        readme_msg, strlen(readme_msg));
3023}
3024
3025static const struct file_operations tracing_readme_fops = {
3026        .open           = tracing_open_generic,
3027        .read           = tracing_readme_read,
3028        .llseek         = generic_file_llseek,
3029};
3030
3031static ssize_t
3032tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
3033                                size_t cnt, loff_t *ppos)
3034{
3035        char *buf_comm;
3036        char *file_buf;
3037        char *buf;
3038        int len = 0;
3039        int pid;
3040        int i;
3041
3042        file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);
3043        if (!file_buf)
3044                return -ENOMEM;
3045
3046        buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);
3047        if (!buf_comm) {
3048                kfree(file_buf);
3049                return -ENOMEM;
3050        }
3051
3052        buf = file_buf;
3053
3054        for (i = 0; i < SAVED_CMDLINES; i++) {
3055                int r;
3056
3057                pid = map_cmdline_to_pid[i];
3058                if (pid == -1 || pid == NO_CMDLINE_MAP)
3059                        continue;
3060
3061                trace_find_cmdline(pid, buf_comm);
3062                r = sprintf(buf, "%d %s\n", pid, buf_comm);
3063                buf += r;
3064                len += r;
3065        }
3066
3067        len = simple_read_from_buffer(ubuf, cnt, ppos,
3068                                      file_buf, len);
3069
3070        kfree(file_buf);
3071        kfree(buf_comm);
3072
3073        return len;
3074}
3075
3076static const struct file_operations tracing_saved_cmdlines_fops = {
3077    .open       = tracing_open_generic,
3078    .read       = tracing_saved_cmdlines_read,
3079    .llseek     = generic_file_llseek,
3080};
3081
3082static ssize_t
3083tracing_set_trace_read(struct file *filp, char __user *ubuf,
3084                       size_t cnt, loff_t *ppos)
3085{
3086        char buf[MAX_TRACER_SIZE+2];
3087        int r;
3088
3089        mutex_lock(&trace_types_lock);
3090        r = sprintf(buf, "%s\n", current_trace->name);
3091        mutex_unlock(&trace_types_lock);
3092
3093        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3094}
3095
3096int tracer_init(struct tracer *t, struct trace_array *tr)
3097{
3098        tracing_reset_online_cpus(tr);
3099        return t->init(tr);
3100}
3101
3102static void set_buffer_entries(struct trace_array *tr, unsigned long val)
3103{
3104        int cpu;
3105        for_each_tracing_cpu(cpu)
3106                tr->data[cpu]->entries = val;
3107}
3108
3109/* resize @tr's buffer to the size of @size_tr's entries */
3110static int resize_buffer_duplicate_size(struct trace_array *tr,
3111                                        struct trace_array *size_tr, int cpu_id)
3112{
3113        int cpu, ret = 0;
3114
3115        if (cpu_id == RING_BUFFER_ALL_CPUS) {
3116                for_each_tracing_cpu(cpu) {
3117                        ret = ring_buffer_resize(tr->buffer,
3118                                        size_tr->data[cpu]->entries, cpu);
3119                        if (ret < 0)
3120                                break;
3121                        tr->data[cpu]->entries = size_tr->data[cpu]->entries;
3122                }
3123        } else {
3124                ret = ring_buffer_resize(tr->buffer,
3125                                        size_tr->data[cpu_id]->entries, cpu_id);
3126                if (ret == 0)
3127                        tr->data[cpu_id]->entries =
3128                                size_tr->data[cpu_id]->entries;
3129        }
3130
3131        return ret;
3132}
3133
3134static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
3135{
3136        int ret;
3137
3138        /*
3139         * If kernel or user changes the size of the ring buffer
3140         * we use the size that was given, and we can forget about
3141         * expanding it later.
3142         */
3143        ring_buffer_expanded = 1;
3144
3145        /* May be called before buffers are initialized */
3146        if (!global_trace.buffer)
3147                return 0;
3148
3149        ret = ring_buffer_resize(global_trace.buffer, size, cpu);
3150        if (ret < 0)
3151                return ret;
3152
3153        if (!current_trace->use_max_tr)
3154                goto out;
3155
3156        ret = ring_buffer_resize(max_tr.buffer, size, cpu);
3157        if (ret < 0) {
3158                int r = resize_buffer_duplicate_size(&global_trace,
3159                                                     &global_trace, cpu);
3160                if (r < 0) {
3161                        /*
3162                         * AARGH! We are left with different
3163                         * size max buffer!!!!
3164                         * The max buffer is our "snapshot" buffer.
3165                         * When a tracer needs a snapshot (one of the
3166                         * latency tracers), it swaps the max buffer
3167                         * with the saved snap shot. We succeeded to
3168                         * update the size of the main buffer, but failed to
3169                         * update the size of the max buffer. But when we tried
3170                         * to reset the main buffer to the original size, we
3171                         * failed there too. This is very unlikely to
3172                         * happen, but if it does, warn and kill all
3173                         * tracing.
3174                         */
3175                        WARN_ON(1);
3176                        tracing_disabled = 1;
3177                }
3178                return ret;
3179        }
3180
3181        if (cpu == RING_BUFFER_ALL_CPUS)
3182                set_buffer_entries(&max_tr, size);
3183        else
3184                max_tr.data[cpu]->entries = size;
3185
3186 out:
3187        if (cpu == RING_BUFFER_ALL_CPUS)
3188                set_buffer_entries(&global_trace, size);
3189        else
3190                global_trace.data[cpu]->entries = size;
3191
3192        return ret;
3193}
3194
3195static ssize_t tracing_resize_ring_buffer(unsigned long size, int cpu_id)
3196{
3197        int ret = size;
3198
3199        mutex_lock(&trace_types_lock);
3200
3201        if (cpu_id != RING_BUFFER_ALL_CPUS) {
3202                /* make sure, this cpu is enabled in the mask */
3203                if (!cpumask_test_cpu(cpu_id, tracing_buffer_mask)) {
3204                        ret = -EINVAL;
3205                        goto out;
3206                }
3207        }
3208
3209        ret = __tracing_resize_ring_buffer(size, cpu_id);
3210        if (ret < 0)
3211                ret = -ENOMEM;
3212
3213out:
3214        mutex_unlock(&trace_types_lock);
3215
3216        return ret;
3217}
3218
3219
3220/**
3221 * tracing_update_buffers - used by tracing facility to expand ring buffers
3222 *
3223 * To save on memory when the tracing is never used on a system with it
3224 * configured in. The ring buffers are set to a minimum size. But once
3225 * a user starts to use the tracing facility, then they need to grow
3226 * to their default size.
3227 *
3228 * This function is to be called when a tracer is about to be used.
3229 */
3230int tracing_update_buffers(void)
3231{
3232        int ret = 0;
3233
3234        mutex_lock(&trace_types_lock);
3235        if (!ring_buffer_expanded)
3236                ret = __tracing_resize_ring_buffer(trace_buf_size,
3237                                                RING_BUFFER_ALL_CPUS);
3238        mutex_unlock(&trace_types_lock);
3239
3240        return ret;
3241}
3242
3243struct trace_option_dentry;
3244
3245static struct trace_option_dentry *
3246create_trace_option_files(struct tracer *tracer);
3247
3248static void
3249destroy_trace_option_files(struct trace_option_dentry *topts);
3250
3251static int tracing_set_tracer(const char *buf)
3252{
3253        static struct trace_option_dentry *topts;
3254        struct trace_array *tr = &global_trace;
3255        struct tracer *t;
3256        bool had_max_tr;
3257        int ret = 0;
3258
3259        mutex_lock(&trace_types_lock);
3260
3261        if (!ring_buffer_expanded) {
3262                ret = __tracing_resize_ring_buffer(trace_buf_size,
3263                                                RING_BUFFER_ALL_CPUS);
3264                if (ret < 0)
3265                        goto out;
3266                ret = 0;
3267        }
3268
3269        for (t = trace_types; t; t = t->next) {
3270                if (strcmp(t->name, buf) == 0)
3271                        break;
3272        }
3273        if (!t) {
3274                ret = -EINVAL;
3275                goto out;
3276        }
3277        if (t == current_trace)
3278                goto out;
3279
3280        trace_branch_disable();
3281
3282        current_trace->enabled = false;
3283
3284        if (current_trace->reset)
3285                current_trace->reset(tr);
3286
3287        had_max_tr = current_trace->allocated_snapshot;
3288        current_trace = &nop_trace;
3289
3290        if (had_max_tr && !t->use_max_tr) {
3291                /*
3292                 * We need to make sure that the update_max_tr sees that
3293                 * current_trace changed to nop_trace to keep it from
3294                 * swapping the buffers after we resize it.
3295                 * The update_max_tr is called from interrupts disabled
3296                 * so a synchronized_sched() is sufficient.
3297                 */
3298                synchronize_sched();
3299                /*
3300                 * We don't free the ring buffer. instead, resize it because
3301                 * The max_tr ring buffer has some state (e.g. ring->clock) and
3302                 * we want preserve it.
3303                 */
3304                ring_buffer_resize(max_tr.buffer, 1, RING_BUFFER_ALL_CPUS);
3305                set_buffer_entries(&max_tr, 1);
3306                tracing_reset_online_cpus(&max_tr);
3307                current_trace->allocated_snapshot = false;
3308        }
3309        destroy_trace_option_files(topts);
3310
3311        topts = create_trace_option_files(t);
3312        if (t->use_max_tr && !had_max_tr) {
3313                /* we need to make per cpu buffer sizes equivalent */
3314                ret = resize_buffer_duplicate_size(&max_tr, &global_trace,
3315                                                   RING_BUFFER_ALL_CPUS);
3316                if (ret < 0)
3317                        goto out;
3318                t->allocated_snapshot = true;
3319        }
3320
3321        if (t->init) {
3322                ret = tracer_init(t, tr);
3323                if (ret)
3324                        goto out;
3325        }
3326
3327        current_trace = t;
3328        current_trace->enabled = true;
3329        trace_branch_enable(tr);
3330 out:
3331        mutex_unlock(&trace_types_lock);
3332
3333        return ret;
3334}
3335
3336static ssize_t
3337tracing_set_trace_write(struct file *filp, const char __user *ubuf,
3338                        size_t cnt, loff_t *ppos)
3339{
3340        char buf[MAX_TRACER_SIZE+1];
3341        int i;
3342        size_t ret;
3343        int err;
3344
3345        ret = cnt;
3346
3347        if (cnt > MAX_TRACER_SIZE)
3348                cnt = MAX_TRACER_SIZE;
3349
3350        if (copy_from_user(&buf, ubuf, cnt))
3351                return -EFAULT;
3352
3353        buf[cnt] = 0;
3354
3355        /* strip ending whitespace. */
3356        for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
3357                buf[i] = 0;
3358
3359        err = tracing_set_tracer(buf);
3360        if (err)
3361                return err;
3362
3363        *ppos += ret;
3364
3365        return ret;
3366}
3367
3368static ssize_t
3369tracing_max_lat_read(struct file *filp, char __user *ubuf,
3370                     size_t cnt, loff_t *ppos)
3371{
3372        unsigned long *ptr = filp->private_data;
3373        char buf[64];
3374        int r;
3375
3376        r = snprintf(buf, sizeof(buf), "%ld\n",
3377                     *ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
3378        if (r > sizeof(buf))
3379                r = sizeof(buf);
3380        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3381}
3382
3383static ssize_t
3384tracing_max_lat_write(struct file *filp, const char __user *ubuf,
3385                      size_t cnt, loff_t *ppos)
3386{
3387        unsigned long *ptr = filp->private_data;
3388        unsigned long val;
3389        int ret;
3390
3391        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
3392        if (ret)
3393                return ret;
3394
3395        *ptr = val * 1000;
3396
3397        return cnt;
3398}
3399
3400static int tracing_open_pipe(struct inode *inode, struct file *filp)
3401{
3402        long cpu_file = (long) inode->i_private;
3403        struct trace_iterator *iter;
3404        int ret = 0;
3405
3406        if (tracing_disabled)
3407                return -ENODEV;
3408
3409        mutex_lock(&trace_types_lock);
3410
3411        /* create a buffer to store the information to pass to userspace */
3412        iter = kzalloc(sizeof(*iter), GFP_KERNEL);
3413        if (!iter) {
3414                ret = -ENOMEM;
3415                goto out;
3416        }
3417
3418        /*
3419         * We make a copy of the current tracer to avoid concurrent
3420         * changes on it while we are reading.
3421         */
3422        iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
3423        if (!iter->trace) {
3424                ret = -ENOMEM;
3425                goto fail;
3426        }
3427        *iter->trace = *current_trace;
3428
3429        if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
3430                ret = -ENOMEM;
3431                goto fail;
3432        }
3433
3434        /* trace pipe does not show start of buffer */
3435        cpumask_setall(iter->started);
3436
3437        if (trace_flags & TRACE_ITER_LATENCY_FMT)
3438                iter->iter_flags |= TRACE_FILE_LAT_FMT;
3439
3440        /* Output in nanoseconds only if we are using a clock in nanoseconds. */
3441        if (trace_clocks[trace_clock_id].in_ns)
3442                iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
3443
3444        iter->cpu_file = cpu_file;
3445        iter->tr = &global_trace;
3446        mutex_init(&iter->mutex);
3447        filp->private_data = iter;
3448
3449        if (iter->trace->pipe_open)
3450                iter->trace->pipe_open(iter);
3451
3452        nonseekable_open(inode, filp);
3453out:
3454        mutex_unlock(&trace_types_lock);
3455        return ret;
3456
3457fail:
3458        kfree(iter->trace);
3459        kfree(iter);
3460        mutex_unlock(&trace_types_lock);
3461        return ret;
3462}
3463
3464static int tracing_release_pipe(struct inode *inode, struct file *file)
3465{
3466        struct trace_iterator *iter = file->private_data;
3467
3468        mutex_lock(&trace_types_lock);
3469
3470        if (iter->trace->pipe_close)
3471                iter->trace->pipe_close(iter);
3472
3473        mutex_unlock(&trace_types_lock);
3474
3475        free_cpumask_var(iter->started);
3476        mutex_destroy(&iter->mutex);
3477        kfree(iter->trace);
3478        kfree(iter);
3479
3480        return 0;
3481}
3482
3483static unsigned int
3484tracing_poll_pipe(struct file *filp, poll_table *poll_table)
3485{
3486        struct trace_iterator *iter = filp->private_data;
3487
3488        if (trace_flags & TRACE_ITER_BLOCK) {
3489                /*
3490                 * Always select as readable when in blocking mode
3491                 */
3492                return POLLIN | POLLRDNORM;
3493        } else {
3494                if (!trace_empty(iter))
3495                        return POLLIN | POLLRDNORM;
3496                poll_wait(filp, &trace_wait, poll_table);
3497                if (!trace_empty(iter))
3498                        return POLLIN | POLLRDNORM;
3499
3500                return 0;
3501        }
3502}
3503
3504/*
3505 * This is a make-shift waitqueue.
3506 * A tracer might use this callback on some rare cases:
3507 *
3508 *  1) the current tracer might hold the runqueue lock when it wakes up
3509 *     a reader, hence a deadlock (sched, function, and function graph tracers)
3510 *  2) the function tracers, trace all functions, we don't want
3511 *     the overhead of calling wake_up and friends
3512 *     (and tracing them too)
3513 *
3514 *     Anyway, this is really very primitive wakeup.
3515 */
3516void poll_wait_pipe(struct trace_iterator *iter)
3517{
3518        set_current_state(TASK_INTERRUPTIBLE);
3519        /* sleep for 100 msecs, and try again. */
3520        schedule_timeout(HZ / 10);
3521}
3522
3523/* Must be called with trace_types_lock mutex held. */
3524static int tracing_wait_pipe(struct file *filp)
3525{
3526        struct trace_iterator *iter = filp->private_data;
3527
3528        while (trace_empty(iter)) {
3529
3530                if ((filp->f_flags & O_NONBLOCK)) {
3531                        return -EAGAIN;
3532                }
3533
3534                mutex_unlock(&iter->mutex);
3535
3536                iter->trace->wait_pipe(iter);
3537
3538                mutex_lock(&iter->mutex);
3539
3540                if (signal_pending(current))
3541                        return -EINTR;
3542
3543                /*
3544                 * We block until we read something and tracing is disabled.
3545                 * We still block if tracing is disabled, but we have never
3546                 * read anything. This allows a user to cat this file, and
3547                 * then enable tracing. But after we have read something,
3548                 * we give an EOF when tracing is again disabled.
3549                 *
3550                 * iter->pos will be 0 if we haven't read anything.
3551                 */
3552                if (!tracing_is_enabled() && iter->pos)
3553                        break;
3554        }
3555
3556        return 1;
3557}
3558
3559/*
3560 * Consumer reader.
3561 */
3562static ssize_t
3563tracing_read_pipe(struct file *filp, char __user *ubuf,
3564                  size_t cnt, loff_t *ppos)
3565{
3566        struct trace_iterator *iter = filp->private_data;
3567        ssize_t sret;
3568
3569        /* return any leftover data */
3570        sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
3571        if (sret != -EBUSY)
3572                return sret;
3573
3574        trace_seq_init(&iter->seq);
3575
3576        /* copy the tracer to avoid using a global lock all around */
3577        mutex_lock(&trace_types_lock);
3578        if (unlikely(iter->trace->name != current_trace->name))
3579                *iter->trace = *current_trace;
3580        mutex_unlock(&trace_types_lock);
3581
3582        /*
3583         * Avoid more than one consumer on a single file descriptor
3584         * This is just a matter of traces coherency, the ring buffer itself
3585         * is protected.
3586         */
3587        mutex_lock(&iter->mutex);
3588        if (iter->trace->read) {
3589                sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
3590                if (sret)
3591                        goto out;
3592        }
3593
3594waitagain:
3595        sret = tracing_wait_pipe(filp);
3596        if (sret <= 0)
3597                goto out;
3598
3599        /* stop when tracing is finished */
3600        if (trace_empty(iter)) {
3601                sret = 0;
3602                goto out;
3603        }
3604
3605        if (cnt >= PAGE_SIZE)
3606                cnt = PAGE_SIZE - 1;
3607
3608        /* reset all but tr, trace, and overruns */
3609        memset(&iter->seq, 0,
3610               sizeof(struct trace_iterator) -
3611               offsetof(struct trace_iterator, seq));
3612        iter->pos = -1;
3613
3614        trace_event_read_lock();
3615        trace_access_lock(iter->cpu_file);
3616        while (trace_find_next_entry_inc(iter) != NULL) {
3617                enum print_line_t ret;
3618                int len = iter->seq.len;
3619
3620                ret = print_trace_line(iter);
3621                if (ret == TRACE_TYPE_PARTIAL_LINE) {
3622                        /* don't print partial lines */
3623                        iter->seq.len = len;
3624                        break;
3625                }
3626                if (ret != TRACE_TYPE_NO_CONSUME)
3627                        trace_consume(iter);
3628
3629                if (iter->seq.len >= cnt)
3630                        break;
3631
3632                /*
3633                 * Setting the full flag means we reached the trace_seq buffer
3634                 * size and we should leave by partial output condition above.
3635                 * One of the trace_seq_* functions is not used properly.
3636                 */
3637                WARN_ONCE(iter->seq.full, "full flag set for trace type %d",
3638                          iter->ent->type);
3639        }
3640        trace_access_unlock(iter->cpu_file);
3641        trace_event_read_unlock();
3642
3643        /* Now copy what we have to the user */
3644        sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
3645        if (iter->seq.readpos >= iter->seq.len)
3646                trace_seq_init(&iter->seq);
3647
3648        /*
3649         * If there was nothing to send to user, in spite of consuming trace
3650         * entries, go back to wait for more entries.
3651         */
3652        if (sret == -EBUSY)
3653                goto waitagain;
3654
3655out:
3656        mutex_unlock(&iter->mutex);
3657
3658        return sret;
3659}
3660
3661static void tracing_pipe_buf_release(struct pipe_inode_info *pipe,
3662                                     struct pipe_buffer *buf)
3663{
3664        __free_page(buf->page);
3665}
3666
3667static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
3668                                     unsigned int idx)
3669{
3670        __free_page(spd->pages[idx]);
3671}
3672
3673static const struct pipe_buf_operations tracing_pipe_buf_ops = {
3674        .can_merge              = 0,
3675        .map                    = generic_pipe_buf_map,
3676        .unmap                  = generic_pipe_buf_unmap,
3677        .confirm                = generic_pipe_buf_confirm,
3678        .release                = tracing_pipe_buf_release,
3679        .steal                  = generic_pipe_buf_steal,
3680        .get                    = generic_pipe_buf_get,
3681};
3682
3683static size_t
3684tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
3685{
3686        size_t count;
3687        int ret;
3688
3689        /* Seq buffer is page-sized, exactly what we need. */
3690        for (;;) {
3691                count = iter->seq.len;
3692                ret = print_trace_line(iter);
3693                count = iter->seq.len - count;
3694                if (rem < count) {
3695                        rem = 0;
3696                        iter->seq.len -= count;
3697                        break;
3698                }
3699                if (ret == TRACE_TYPE_PARTIAL_LINE) {
3700                        iter->seq.len -= count;
3701                        break;
3702                }
3703
3704                if (ret != TRACE_TYPE_NO_CONSUME)
3705                        trace_consume(iter);
3706                rem -= count;
3707                if (!trace_find_next_entry_inc(iter))   {
3708                        rem = 0;
3709                        iter->ent = NULL;
3710                        break;
3711                }
3712        }
3713
3714        return rem;
3715}
3716
3717static ssize_t tracing_splice_read_pipe(struct file *filp,
3718                                        loff_t *ppos,
3719                                        struct pipe_inode_info *pipe,
3720                                        size_t len,
3721                                        unsigned int flags)
3722{
3723        struct page *pages_def[PIPE_DEF_BUFFERS];
3724        struct partial_page partial_def[PIPE_DEF_BUFFERS];
3725        struct trace_iterator *iter = filp->private_data;
3726        struct splice_pipe_desc spd = {
3727                .pages          = pages_def,
3728                .partial        = partial_def,
3729                .nr_pages       = 0, /* This gets updated below. */
3730                .nr_pages_max   = PIPE_DEF_BUFFERS,
3731                .flags          = flags,
3732                .ops            = &tracing_pipe_buf_ops,
3733                .spd_release    = tracing_spd_release_pipe,
3734        };
3735        ssize_t ret;
3736        size_t rem;
3737        unsigned int i;
3738
3739        if (splice_grow_spd(pipe, &spd))
3740                return -ENOMEM;
3741
3742        /* copy the tracer to avoid using a global lock all around */
3743        mutex_lock(&trace_types_lock);
3744        if (unlikely(iter->trace->name != current_trace->name))
3745                *iter->trace = *current_trace;
3746        mutex_unlock(&trace_types_lock);
3747
3748        mutex_lock(&iter->mutex);
3749
3750        if (iter->trace->splice_read) {
3751                ret = iter->trace->splice_read(iter, filp,
3752                                               ppos, pipe, len, flags);
3753                if (ret)
3754                        goto out_err;
3755        }
3756
3757        ret = tracing_wait_pipe(filp);
3758        if (ret <= 0)
3759                goto out_err;
3760
3761        if (!iter->ent && !trace_find_next_entry_inc(iter)) {
3762                ret = -EFAULT;
3763                goto out_err;
3764        }
3765
3766        trace_event_read_lock();
3767        trace_access_lock(iter->cpu_file);
3768
3769        /* Fill as many pages as possible. */
3770        for (i = 0, rem = len; i < pipe->buffers && rem; i++) {
3771                spd.pages[i] = alloc_page(GFP_KERNEL);
3772                if (!spd.pages[i])
3773                        break;
3774
3775                rem = tracing_fill_pipe_page(rem, iter);
3776
3777                /* Copy the data into the page, so we can start over. */
3778                ret = trace_seq_to_buffer(&iter->seq,
3779                                          page_address(spd.pages[i]),
3780                                          iter->seq.len);
3781                if (ret < 0) {
3782                        __free_page(spd.pages[i]);
3783                        break;
3784                }
3785                spd.partial[i].offset = 0;
3786                spd.partial[i].len = iter->seq.len;
3787
3788                trace_seq_init(&iter->seq);
3789        }
3790
3791        trace_access_unlock(iter->cpu_file);
3792        trace_event_read_unlock();
3793        mutex_unlock(&iter->mutex);
3794
3795        spd.nr_pages = i;
3796
3797        ret = splice_to_pipe(pipe, &spd);
3798out:
3799        splice_shrink_spd(&spd);
3800        return ret;
3801
3802out_err:
3803        mutex_unlock(&iter->mutex);
3804        goto out;
3805}
3806
3807struct ftrace_entries_info {
3808        struct trace_array      *tr;
3809        int                     cpu;
3810};
3811
3812static int tracing_entries_open(struct inode *inode, struct file *filp)
3813{
3814        struct ftrace_entries_info *info;
3815
3816        if (tracing_disabled)
3817                return -ENODEV;
3818
3819        info = kzalloc(sizeof(*info), GFP_KERNEL);
3820        if (!info)
3821                return -ENOMEM;
3822
3823        info->tr = &global_trace;
3824        info->cpu = (unsigned long)inode->i_private;
3825
3826        filp->private_data = info;
3827
3828        return 0;
3829}
3830
3831static ssize_t
3832tracing_entries_read(struct file *filp, char __user *ubuf,
3833                     size_t cnt, loff_t *ppos)
3834{
3835        struct ftrace_entries_info *info = filp->private_data;
3836        struct trace_array *tr = info->tr;
3837        char buf[64];
3838        int r = 0;
3839        ssize_t ret;
3840
3841        mutex_lock(&trace_types_lock);
3842
3843        if (info->cpu == RING_BUFFER_ALL_CPUS) {
3844                int cpu, buf_size_same;
3845                unsigned long size;
3846
3847                size = 0;
3848                buf_size_same = 1;
3849                /* check if all cpu sizes are same */
3850                for_each_tracing_cpu(cpu) {
3851                        /* fill in the size from first enabled cpu */
3852                        if (size == 0)
3853                                size = tr->data[cpu]->entries;
3854                        if (size != tr->data[cpu]->entries) {
3855                                buf_size_same = 0;
3856                                break;
3857                        }
3858                }
3859
3860                if (buf_size_same) {
3861                        if (!ring_buffer_expanded)
3862                                r = sprintf(buf, "%lu (expanded: %lu)\n",
3863                                            size >> 10,
3864                                            trace_buf_size >> 10);
3865                        else
3866                                r = sprintf(buf, "%lu\n", size >> 10);
3867                } else
3868                        r = sprintf(buf, "X\n");
3869        } else
3870                r = sprintf(buf, "%lu\n", tr->data[info->cpu]->entries >> 10);
3871
3872        mutex_unlock(&trace_types_lock);
3873
3874        ret = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3875        return ret;
3876}
3877
3878static ssize_t
3879tracing_entries_write(struct file *filp, const char __user *ubuf,
3880                      size_t cnt, loff_t *ppos)
3881{
3882        struct ftrace_entries_info *info = filp->private_data;
3883        unsigned long val;
3884        int ret;
3885
3886        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
3887        if (ret)
3888                return ret;
3889
3890        /* must have at least 1 entry */
3891        if (!val)
3892                return -EINVAL;
3893
3894        /* value is in KB */
3895        val <<= 10;
3896
3897        ret = tracing_resize_ring_buffer(val, info->cpu);
3898        if (ret < 0)
3899                return ret;
3900
3901        *ppos += cnt;
3902
3903        return cnt;
3904}
3905
3906static int
3907tracing_entries_release(struct inode *inode, struct file *filp)
3908{
3909        struct ftrace_entries_info *info = filp->private_data;
3910
3911        kfree(info);
3912
3913        return 0;
3914}
3915
3916static ssize_t
3917tracing_total_entries_read(struct file *filp, char __user *ubuf,
3918                                size_t cnt, loff_t *ppos)
3919{
3920        struct trace_array *tr = filp->private_data;
3921        char buf[64];
3922        int r, cpu;
3923        unsigned long size = 0, expanded_size = 0;
3924
3925        mutex_lock(&trace_types_lock);
3926        for_each_tracing_cpu(cpu) {
3927                size += tr->data[cpu]->entries >> 10;
3928                if (!ring_buffer_expanded)
3929                        expanded_size += trace_buf_size >> 10;
3930        }
3931        if (ring_buffer_expanded)
3932                r = sprintf(buf, "%lu\n", size);
3933        else
3934                r = sprintf(buf, "%lu (expanded: %lu)\n", size, expanded_size);
3935        mutex_unlock(&trace_types_lock);
3936
3937        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3938}
3939
3940static ssize_t
3941tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
3942                          size_t cnt, loff_t *ppos)
3943{
3944        /*
3945         * There is no need to read what the user has written, this function
3946         * is just to make sure that there is no error when "echo" is used
3947         */
3948
3949        *ppos += cnt;
3950
3951        return cnt;
3952}
3953
3954static int
3955tracing_free_buffer_release(struct inode *inode, struct file *filp)
3956{
3957        /* disable tracing ? */
3958        if (trace_flags & TRACE_ITER_STOP_ON_FREE)
3959                tracing_off();
3960        /* resize the ring buffer to 0 */
3961        tracing_resize_ring_buffer(0, RING_BUFFER_ALL_CPUS);
3962
3963        return 0;
3964}
3965
3966static ssize_t
3967tracing_mark_write(struct file *filp, const char __user *ubuf,
3968                                        size_t cnt, loff_t *fpos)
3969{
3970        unsigned long addr = (unsigned long)ubuf;
3971        struct ring_buffer_event *event;
3972        struct ring_buffer *buffer;
3973        struct print_entry *entry;
3974        unsigned long irq_flags;
3975        struct page *pages[2];
3976        void *map_page[2];
3977        int nr_pages = 1;
3978        ssize_t written;
3979        int offset;
3980        int size;
3981        int len;
3982        int ret;
3983        int i;
3984
3985        if (tracing_disabled)
3986                return -EINVAL;
3987
3988        if (!(trace_flags & TRACE_ITER_MARKERS))
3989                return -EINVAL;
3990
3991        if (cnt > TRACE_BUF_SIZE)
3992                cnt = TRACE_BUF_SIZE;
3993
3994        /*
3995         * Userspace is injecting traces into the kernel trace buffer.
3996         * We want to be as non intrusive as possible.
3997         * To do so, we do not want to allocate any special buffers
3998         * or take any locks, but instead write the userspace data
3999         * straight into the ring buffer.
4000         *
4001         * First we need to pin the userspace buffer into memory,
4002         * which, most likely it is, because it just referenced it.
4003         * But there's no guarantee that it is. By using get_user_pages_fast()
4004         * and kmap_atomic/kunmap_atomic() we can get access to the
4005         * pages directly. We then write the data directly into the
4006         * ring buffer.
4007         */
4008        BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
4009
4010        /* check if we cross pages */
4011        if ((addr & PAGE_MASK) != ((addr + cnt) & PAGE_MASK))
4012                nr_pages = 2;
4013
4014        offset = addr & (PAGE_SIZE - 1);
4015        addr &= PAGE_MASK;
4016
4017        ret = get_user_pages_fast(addr, nr_pages, 0, pages);
4018        if (ret < nr_pages) {
4019                while (--ret >= 0)
4020                        put_page(pages[ret]);
4021                written = -EFAULT;
4022                goto out;
4023        }
4024
4025        for (i = 0; i < nr_pages; i++)
4026                map_page[i] = kmap_atomic(pages[i]);
4027
4028        local_save_flags(irq_flags);
4029        size = sizeof(*entry) + cnt + 2; /* possible \n added */
4030        buffer = global_trace.buffer;
4031        event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
4032                                          irq_flags, preempt_count());
4033        if (!event) {
4034                /* Ring buffer disabled, return as if not open for write */
4035                written = -EBADF;
4036                goto out_unlock;
4037        }
4038
4039        entry = ring_buffer_event_data(event);
4040        entry->ip = _THIS_IP_;
4041
4042        if (nr_pages == 2) {
4043                len = PAGE_SIZE - offset;
4044                memcpy(&entry->buf, map_page[0] + offset, len);
4045                memcpy(&entry->buf[len], map_page[1], cnt - len);
4046        } else
4047                memcpy(&entry->buf, map_page[0] + offset, cnt);
4048
4049        if (entry->buf[cnt - 1] != '\n') {
4050                entry->buf[cnt] = '\n';
4051                entry->buf[cnt + 1] = '\0';
4052        } else
4053                entry->buf[cnt] = '\0';
4054
4055        __buffer_unlock_commit(buffer, event);
4056
4057        written = cnt;
4058
4059        *fpos += written;
4060
4061 out_unlock:
4062        for (i = 0; i < nr_pages; i++){
4063                kunmap_atomic(map_page[i]);
4064                put_page(pages[i]);
4065        }
4066 out:
4067        return written;
4068}
4069
4070static int tracing_clock_show(struct seq_file *m, void *v)
4071{
4072        int i;
4073
4074        for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
4075                seq_printf(m,
4076                        "%s%s%s%s", i ? " " : "",
4077                        i == trace_clock_id ? "[" : "", trace_clocks[i].name,
4078                        i == trace_clock_id ? "]" : "");
4079        seq_putc(m, '\n');
4080
4081        return 0;
4082}
4083
4084static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
4085                                   size_t cnt, loff_t *fpos)
4086{
4087        char buf[64];
4088        const char *clockstr;
4089        int i;
4090
4091        if (cnt >= sizeof(buf))
4092                return -EINVAL;
4093
4094        if (copy_from_user(&buf, ubuf, cnt))
4095                return -EFAULT;
4096
4097        buf[cnt] = 0;
4098
4099        clockstr = strstrip(buf);
4100
4101        for (i = 0; i < ARRAY_SIZE(trace_clocks); i++) {
4102                if (strcmp(trace_clocks[i].name, clockstr) == 0)
4103                        break;
4104        }
4105        if (i == ARRAY_SIZE(trace_clocks))
4106                return -EINVAL;
4107
4108        trace_clock_id = i;
4109
4110        mutex_lock(&trace_types_lock);
4111
4112        ring_buffer_set_clock(global_trace.buffer, trace_clocks[i].func);
4113        if (max_tr.buffer)
4114                ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
4115
4116        /*
4117         * New clock may not be consistent with the previous clock.
4118         * Reset the buffer so that it doesn't have incomparable timestamps.
4119         */
4120        tracing_reset_online_cpus(&global_trace);
4121        tracing_reset_online_cpus(&max_tr);
4122
4123        mutex_unlock(&trace_types_lock);
4124
4125        *fpos += cnt;
4126
4127        return cnt;
4128}
4129
4130static int tracing_clock_open(struct inode *inode, struct file *file)
4131{
4132        if (tracing_disabled)
4133                return -ENODEV;
4134        return single_open(file, tracing_clock_show, NULL);
4135}
4136
4137#ifdef CONFIG_TRACER_SNAPSHOT
4138static int tracing_snapshot_open(struct inode *inode, struct file *file)
4139{
4140        struct trace_iterator *iter;
4141        int ret = 0;
4142
4143        if (file->f_mode & FMODE_READ) {
4144                iter = __tracing_open(inode, file, true);
4145                if (IS_ERR(iter))
4146                        ret = PTR_ERR(iter);
4147        }
4148        return ret;
4149}
4150
4151static ssize_t
4152tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
4153                       loff_t *ppos)
4154{
4155        unsigned long val;
4156        int ret;
4157
4158        ret = tracing_update_buffers();
4159        if (ret < 0)
4160                return ret;
4161
4162        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
4163        if (ret)
4164                return ret;
4165
4166        mutex_lock(&trace_types_lock);
4167
4168        if (current_trace->use_max_tr) {
4169                ret = -EBUSY;
4170                goto out;
4171        }
4172
4173        switch (val) {
4174        case 0:
4175                if (current_trace->allocated_snapshot) {
4176                        /* free spare buffer */
4177                        ring_buffer_resize(max_tr.buffer, 1,
4178                                           RING_BUFFER_ALL_CPUS);
4179                        set_buffer_entries(&max_tr, 1);
4180                        tracing_reset_online_cpus(&max_tr);
4181                        current_trace->allocated_snapshot = false;
4182                }
4183                break;
4184        case 1:
4185                if (!current_trace->allocated_snapshot) {
4186                        /* allocate spare buffer */
4187                        ret = resize_buffer_duplicate_size(&max_tr,
4188                                        &global_trace, RING_BUFFER_ALL_CPUS);
4189                        if (ret < 0)
4190                                break;
4191                        current_trace->allocated_snapshot = true;
4192                }
4193
4194                local_irq_disable();
4195                /* Now, we're going to swap */
4196                update_max_tr(&global_trace, current, smp_processor_id());
4197                local_irq_enable();
4198                break;
4199        default:
4200                if (current_trace->allocated_snapshot)
4201                        tracing_reset_online_cpus(&max_tr);
4202                break;
4203        }
4204
4205        if (ret >= 0) {
4206                *ppos += cnt;
4207                ret = cnt;
4208        }
4209out:
4210        mutex_unlock(&trace_types_lock);
4211        return ret;
4212}
4213#endif /* CONFIG_TRACER_SNAPSHOT */
4214
4215
4216static const struct file_operations tracing_max_lat_fops = {
4217        .open           = tracing_open_generic,
4218        .read           = tracing_max_lat_read,
4219        .write          = tracing_max_lat_write,
4220        .llseek         = generic_file_llseek,
4221};
4222
4223static const struct file_operations set_tracer_fops = {
4224        .open           = tracing_open_generic,
4225        .read           = tracing_set_trace_read,
4226        .write          = tracing_set_trace_write,
4227        .llseek         = generic_file_llseek,
4228};
4229
4230static const struct file_operations tracing_pipe_fops = {
4231        .open           = tracing_open_pipe,
4232        .poll           = tracing_poll_pipe,
4233        .read           = tracing_read_pipe,
4234        .splice_read    = tracing_splice_read_pipe,
4235        .release        = tracing_release_pipe,
4236        .llseek         = no_llseek,
4237};
4238
4239static const struct file_operations tracing_entries_fops = {
4240        .open           = tracing_entries_open,
4241        .read           = tracing_entries_read,
4242        .write          = tracing_entries_write,
4243        .release        = tracing_entries_release,
4244        .llseek         = generic_file_llseek,
4245};
4246
4247static const struct file_operations tracing_total_entries_fops = {
4248        .open           = tracing_open_generic,
4249        .read           = tracing_total_entries_read,
4250        .llseek         = generic_file_llseek,
4251};
4252
4253static const struct file_operations tracing_free_buffer_fops = {
4254        .write          = tracing_free_buffer_write,
4255        .release        = tracing_free_buffer_release,
4256};
4257
4258static const struct file_operations tracing_mark_fops = {
4259        .open           = tracing_open_generic,
4260        .write          = tracing_mark_write,
4261        .llseek         = generic_file_llseek,
4262};
4263
4264static const struct file_operations trace_clock_fops = {
4265        .open           = tracing_clock_open,
4266        .read           = seq_read,
4267        .llseek         = seq_lseek,
4268        .release        = single_release,
4269        .write          = tracing_clock_write,
4270};
4271
4272#ifdef CONFIG_TRACER_SNAPSHOT
4273static const struct file_operations snapshot_fops = {
4274        .open           = tracing_snapshot_open,
4275        .read           = seq_read,
4276        .write          = tracing_snapshot_write,
4277        .llseek         = tracing_seek,
4278        .release        = tracing_release,
4279};
4280#endif /* CONFIG_TRACER_SNAPSHOT */
4281
4282struct ftrace_buffer_info {
4283        struct trace_array      *tr;
4284        void                    *spare;
4285        int                     cpu;
4286        unsigned int            read;
4287};
4288
4289static int tracing_buffers_open(struct inode *inode, struct file *filp)
4290{
4291        int cpu = (int)(long)inode->i_private;
4292        struct ftrace_buffer_info *info;
4293
4294        if (tracing_disabled)
4295                return -ENODEV;
4296
4297        info = kzalloc(sizeof(*info), GFP_KERNEL);
4298        if (!info)
4299                return -ENOMEM;
4300
4301        info->tr        = &global_trace;
4302        info->cpu       = cpu;
4303        info->spare     = NULL;
4304        /* Force reading ring buffer for first read */
4305        info->read      = (unsigned int)-1;
4306
4307        filp->private_data = info;
4308
4309        return nonseekable_open(inode, filp);
4310}
4311
4312static ssize_t
4313tracing_buffers_read(struct file *filp, char __user *ubuf,
4314                     size_t count, loff_t *ppos)
4315{
4316        struct ftrace_buffer_info *info = filp->private_data;
4317        ssize_t ret;
4318        size_t size;
4319
4320        if (!count)
4321                return 0;
4322
4323        if (!info->spare)
4324                info->spare = ring_buffer_alloc_read_page(info->tr->buffer, info->cpu);
4325        if (!info->spare)
4326                return -ENOMEM;
4327
4328        /* Do we have previous read data to read? */
4329        if (info->read < PAGE_SIZE)
4330                goto read;
4331
4332        trace_access_lock(info->cpu);
4333        ret = ring_buffer_read_page(info->tr->buffer,
4334                                    &info->spare,
4335                                    count,
4336                                    info->cpu, 0);
4337        trace_access_unlock(info->cpu);
4338        if (ret < 0)
4339                return 0;
4340
4341        info->read = 0;
4342
4343read:
4344        size = PAGE_SIZE - info->read;
4345        if (size > count)
4346                size = count;
4347
4348        ret = copy_to_user(ubuf, info->spare + info->read, size);
4349        if (ret == size)
4350                return -EFAULT;
4351        size -= ret;
4352
4353        *ppos += size;
4354        info->read += size;
4355
4356        return size;
4357}
4358
4359static int tracing_buffers_release(struct inode *inode, struct file *file)
4360{
4361        struct ftrace_buffer_info *info = file->private_data;
4362
4363        if (info->spare)
4364                ring_buffer_free_read_page(info->tr->buffer, info->spare);
4365        kfree(info);
4366
4367        return 0;
4368}
4369
4370struct buffer_ref {
4371        struct ring_buffer      *buffer;
4372        void                    *page;
4373        int                     ref;
4374};
4375
4376static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
4377                                    struct pipe_buffer *buf)
4378{
4379        struct buffer_ref *ref = (struct buffer_ref *)buf->private;
4380
4381        if (--ref->ref)
4382                return;
4383
4384        ring_buffer_free_read_page(ref->buffer, ref->page);
4385        kfree(ref);
4386        buf->private = 0;
4387}
4388
4389static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
4390                                struct pipe_buffer *buf)
4391{
4392        struct buffer_ref *ref = (struct buffer_ref *)buf->private;
4393
4394        ref->ref++;
4395}
4396
4397/* Pipe buffer operations for a buffer. */
4398static const struct pipe_buf_operations buffer_pipe_buf_ops = {
4399        .can_merge              = 0,
4400        .map                    = generic_pipe_buf_map,
4401        .unmap                  = generic_pipe_buf_unmap,
4402        .confirm                = generic_pipe_buf_confirm,
4403        .release                = buffer_pipe_buf_release,
4404        .steal                  = generic_pipe_buf_steal,
4405        .get                    = buffer_pipe_buf_get,
4406};
4407
4408/*
4409 * Callback from splice_to_pipe(), if we need to release some pages
4410 * at the end of the spd in case we error'ed out in filling the pipe.
4411 */
4412static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
4413{
4414        struct buffer_ref *ref =
4415                (struct buffer_ref *)spd->partial[i].private;
4416
4417        if (--ref->ref)
4418                return;
4419
4420        ring_buffer_free_read_page(ref->buffer, ref->page);
4421        kfree(ref);
4422        spd->partial[i].private = 0;
4423}
4424
4425static ssize_t
4426tracing_buffers_splice_read(struct file *file, loff_t *ppos,
4427                            struct pipe_inode_info *pipe, size_t len,
4428                            unsigned int flags)
4429{
4430        struct ftrace_buffer_info *info = file->private_data;
4431        struct partial_page partial_def[PIPE_DEF_BUFFERS];
4432        struct page *pages_def[PIPE_DEF_BUFFERS];
4433        struct splice_pipe_desc spd = {
4434                .pages          = pages_def,
4435                .partial        = partial_def,
4436                .nr_pages_max   = PIPE_DEF_BUFFERS,
4437                .flags          = flags,
4438                .ops            = &buffer_pipe_buf_ops,
4439                .spd_release    = buffer_spd_release,
4440        };
4441        struct buffer_ref *ref;
4442        int entries, size, i;
4443        size_t ret;
4444
4445        if (splice_grow_spd(pipe, &spd))
4446                return -ENOMEM;
4447
4448        if (*ppos & (PAGE_SIZE - 1)) {
4449                ret = -EINVAL;
4450                goto out;
4451        }
4452
4453        if (len & (PAGE_SIZE - 1)) {
4454                if (len < PAGE_SIZE) {
4455                        ret = -EINVAL;
4456                        goto out;
4457                }
4458                len &= PAGE_MASK;
4459        }
4460
4461        trace_access_lock(info->cpu);
4462        entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
4463
4464        for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
4465                struct page *page;
4466                int r;
4467
4468                ref = kzalloc(sizeof(*ref), GFP_KERNEL);
4469                if (!ref)
4470                        break;
4471
4472                ref->ref = 1;
4473                ref->buffer = info->tr->buffer;
4474                ref->page = ring_buffer_alloc_read_page(ref->buffer, info->cpu);
4475                if (!ref->page) {
4476                        kfree(ref);
4477                        break;
4478                }
4479
4480                r = ring_buffer_read_page(ref->buffer, &ref->page,
4481                                          len, info->cpu, 1);
4482                if (r < 0) {
4483                        ring_buffer_free_read_page(ref->buffer, ref->page);
4484                        kfree(ref);
4485                        break;
4486                }
4487
4488                /*
4489                 * zero out any left over data, this is going to
4490                 * user land.
4491                 */
4492                size = ring_buffer_page_len(ref->page);
4493                if (size < PAGE_SIZE)
4494                        memset(ref->page + size, 0, PAGE_SIZE - size);
4495
4496                page = virt_to_page(ref->page);
4497
4498                spd.pages[i] = page;
4499                spd.partial[i].len = PAGE_SIZE;
4500                spd.partial[i].offset = 0;
4501                spd.partial[i].private = (unsigned long)ref;
4502                spd.nr_pages++;
4503                *ppos += PAGE_SIZE;
4504
4505                entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
4506        }
4507
4508        trace_access_unlock(info->cpu);
4509        spd.nr_pages = i;
4510
4511        /* did we read anything? */
4512        if (!spd.nr_pages) {
4513                if (flags & SPLICE_F_NONBLOCK)
4514                        ret = -EAGAIN;
4515                else
4516                        ret = 0;
4517                /* TODO: block */
4518                goto out;
4519        }
4520
4521        ret = splice_to_pipe(pipe, &spd);
4522        splice_shrink_spd(&spd);
4523out:
4524        return ret;
4525}
4526
4527static const struct file_operations tracing_buffers_fops = {
4528        .open           = tracing_buffers_open,
4529        .read           = tracing_buffers_read,
4530        .release        = tracing_buffers_release,
4531        .splice_read    = tracing_buffers_splice_read,
4532        .llseek         = no_llseek,
4533};
4534
4535static ssize_t
4536tracing_stats_read(struct file *filp, char __user *ubuf,
4537                   size_t count, loff_t *ppos)
4538{
4539        unsigned long cpu = (unsigned long)filp->private_data;
4540        struct trace_array *tr = &global_trace;
4541        struct trace_seq *s;
4542        unsigned long cnt;
4543        unsigned long long t;
4544        unsigned long usec_rem;
4545
4546        s = kmalloc(sizeof(*s), GFP_KERNEL);
4547        if (!s)
4548                return -ENOMEM;
4549
4550        trace_seq_init(s);
4551
4552        cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
4553        trace_seq_printf(s, "entries: %ld\n", cnt);
4554
4555        cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
4556        trace_seq_printf(s, "overrun: %ld\n", cnt);
4557
4558        cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
4559        trace_seq_printf(s, "commit overrun: %ld\n", cnt);
4560
4561        cnt = ring_buffer_bytes_cpu(tr->buffer, cpu);
4562        trace_seq_printf(s, "bytes: %ld\n", cnt);
4563
4564        if (trace_clocks[trace_clock_id].in_ns) {
4565                /* local or global for trace_clock */
4566                t = ns2usecs(ring_buffer_oldest_event_ts(tr->buffer, cpu));
4567                usec_rem = do_div(t, USEC_PER_SEC);
4568                trace_seq_printf(s, "oldest event ts: %5llu.%06lu\n",
4569                                                                t, usec_rem);
4570
4571                t = ns2usecs(ring_buffer_time_stamp(tr->buffer, cpu));
4572                usec_rem = do_div(t, USEC_PER_SEC);
4573                trace_seq_printf(s, "now ts: %5llu.%06lu\n", t, usec_rem);
4574        } else {
4575                /* counter or tsc mode for trace_clock */
4576                trace_seq_printf(s, "oldest event ts: %llu\n",
4577                                ring_buffer_oldest_event_ts(tr->buffer, cpu));
4578
4579                trace_seq_printf(s, "now ts: %llu\n",
4580                                ring_buffer_time_stamp(tr->buffer, cpu));
4581        }
4582
4583        cnt = ring_buffer_dropped_events_cpu(tr->buffer, cpu);
4584        trace_seq_printf(s, "dropped events: %ld\n", cnt);
4585
4586        cnt = ring_buffer_read_events_cpu(tr->buffer, cpu);
4587        trace_seq_printf(s, "read events: %ld\n", cnt);
4588
4589        count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
4590
4591        kfree(s);
4592
4593        return count;
4594}
4595
4596static const struct file_operations tracing_stats_fops = {
4597        .open           = tracing_open_generic,
4598        .read           = tracing_stats_read,
4599        .llseek         = generic_file_llseek,
4600};
4601
4602#ifdef CONFIG_DYNAMIC_FTRACE
4603
4604int __weak ftrace_arch_read_dyn_info(char *buf, int size)
4605{
4606        return 0;
4607}
4608
4609static ssize_t
4610tracing_read_dyn_info(struct file *filp, char __user *ubuf,
4611                  size_t cnt, loff_t *ppos)
4612{
4613        static char ftrace_dyn_info_buffer[1024];
4614        static DEFINE_MUTEX(dyn_info_mutex);
4615        unsigned long *p = filp->private_data;
4616        char *buf = ftrace_dyn_info_buffer;
4617        int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
4618        int r;
4619
4620        mutex_lock(&dyn_info_mutex);
4621        r = sprintf(buf, "%ld ", *p);
4622
4623        r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
4624        buf[r++] = '\n';
4625
4626        r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
4627
4628        mutex_unlock(&dyn_info_mutex);
4629
4630        return r;
4631}
4632
4633static const struct file_operations tracing_dyn_info_fops = {
4634        .open           = tracing_open_generic,
4635        .read           = tracing_read_dyn_info,
4636        .llseek         = generic_file_llseek,
4637};
4638#endif
4639
4640static struct dentry *d_tracer;
4641
4642struct dentry *tracing_init_dentry(void)
4643{
4644        static int once;
4645
4646        if (d_tracer)
4647                return d_tracer;
4648
4649        if (!debugfs_initialized())
4650                return NULL;
4651
4652        d_tracer = debugfs_create_dir("tracing", NULL);
4653
4654        if (!d_tracer && !once) {
4655                once = 1;
4656                pr_warning("Could not create debugfs directory 'tracing'\n");
4657                return NULL;
4658        }
4659
4660        return d_tracer;
4661}
4662
4663static struct dentry *d_percpu;
4664
4665static struct dentry *tracing_dentry_percpu(void)
4666{
4667        static int once;
4668        struct dentry *d_tracer;
4669
4670        if (d_percpu)
4671                return d_percpu;
4672
4673        d_tracer = tracing_init_dentry();
4674
4675        if (!d_tracer)
4676                return NULL;
4677
4678        d_percpu = debugfs_create_dir("per_cpu", d_tracer);
4679
4680        if (!d_percpu && !once) {
4681                once = 1;
4682                pr_warning("Could not create debugfs directory 'per_cpu'\n");
4683                return NULL;
4684        }
4685
4686        return d_percpu;
4687}
4688
4689static void tracing_init_debugfs_percpu(long cpu)
4690{
4691        struct dentry *d_percpu = tracing_dentry_percpu();
4692        struct dentry *d_cpu;
4693        char cpu_dir[30]; /* 30 characters should be more than enough */
4694
4695        if (!d_percpu)
4696                return;
4697
4698        snprintf(cpu_dir, 30, "cpu%ld", cpu);
4699        d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
4700        if (!d_cpu) {
4701                pr_warning("Could not create debugfs '%s' entry\n", cpu_dir);
4702                return;
4703        }
4704
4705        /* per cpu trace_pipe */
4706        trace_create_file("trace_pipe", 0444, d_cpu,
4707                        (void *) cpu, &tracing_pipe_fops);
4708
4709        /* per cpu trace */
4710        trace_create_file("trace", 0644, d_cpu,
4711                        (void *) cpu, &tracing_fops);
4712
4713        trace_create_file("trace_pipe_raw", 0444, d_cpu,
4714                        (void *) cpu, &tracing_buffers_fops);
4715
4716        trace_create_file("stats", 0444, d_cpu,
4717                        (void *) cpu, &tracing_stats_fops);
4718
4719        trace_create_file("buffer_size_kb", 0444, d_cpu,
4720                        (void *) cpu, &tracing_entries_fops);
4721}
4722
4723#ifdef CONFIG_FTRACE_SELFTEST
4724/* Let selftest have access to static functions in this file */
4725#include "trace_selftest.c"
4726#endif
4727
4728struct trace_option_dentry {
4729        struct tracer_opt               *opt;
4730        struct tracer_flags             *flags;
4731        struct dentry                   *entry;
4732};
4733
4734static ssize_t
4735trace_options_read(struct file *filp, char __user *ubuf, size_t cnt,
4736                        loff_t *ppos)
4737{
4738        struct trace_option_dentry *topt = filp->private_data;
4739        char *buf;
4740
4741        if (topt->flags->val & topt->opt->bit)
4742                buf = "1\n";
4743        else
4744                buf = "0\n";
4745
4746        return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
4747}
4748
4749static ssize_t
4750trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
4751                         loff_t *ppos)
4752{
4753        struct trace_option_dentry *topt = filp->private_data;
4754        unsigned long val;
4755        int ret;
4756
4757        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
4758        if (ret)
4759                return ret;
4760
4761        if (val != 0 && val != 1)
4762                return -EINVAL;
4763
4764        if (!!(topt->flags->val & topt->opt->bit) != val) {
4765                mutex_lock(&trace_types_lock);
4766                ret = __set_tracer_option(current_trace, topt->flags,
4767                                          topt->opt, !val);
4768                mutex_unlock(&trace_types_lock);
4769                if (ret)
4770                        return ret;
4771        }
4772
4773        *ppos += cnt;
4774
4775        return cnt;
4776}
4777
4778
4779static const struct file_operations trace_options_fops = {
4780        .open = tracing_open_generic,
4781        .read = trace_options_read,
4782        .write = trace_options_write,
4783        .llseek = generic_file_llseek,
4784};
4785
4786static ssize_t
4787trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,
4788                        loff_t *ppos)
4789{
4790        long index = (long)filp->private_data;
4791        char *buf;
4792
4793        if (trace_flags & (1 << index))
4794                buf = "1\n";
4795        else
4796                buf = "0\n";
4797
4798        return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
4799}
4800
4801static ssize_t
4802trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
4803                         loff_t *ppos)
4804{
4805        long index = (long)filp->private_data;
4806        unsigned long val;
4807        int ret;
4808
4809        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
4810        if (ret)
4811                return ret;
4812
4813        if (val != 0 && val != 1)
4814                return -EINVAL;
4815
4816        mutex_lock(&trace_types_lock);
4817        ret = set_tracer_flag(1 << index, val);
4818        mutex_unlock(&trace_types_lock);
4819
4820        if (ret < 0)
4821                return ret;
4822
4823        *ppos += cnt;
4824
4825        return cnt;
4826}
4827
4828static const struct file_operations trace_options_core_fops = {
4829        .open = tracing_open_generic,
4830        .read = trace_options_core_read,
4831        .write = trace_options_core_write,
4832        .llseek = generic_file_llseek,
4833};
4834
4835struct dentry *trace_create_file(const char *name,
4836                                 umode_t mode,
4837                                 struct dentry *parent,
4838                                 void *data,
4839                                 const struct file_operations *fops)
4840{
4841        struct dentry *ret;
4842
4843        ret = debugfs_create_file(name, mode, parent, data, fops);
4844        if (!ret)
4845                pr_warning("Could not create debugfs '%s' entry\n", name);
4846
4847        return ret;
4848}
4849
4850
4851static struct dentry *trace_options_init_dentry(void)
4852{
4853        struct dentry *d_tracer;
4854        static struct dentry *t_options;
4855
4856        if (t_options)
4857                return t_options;
4858
4859        d_tracer = tracing_init_dentry();
4860        if (!d_tracer)
4861                return NULL;
4862
4863        t_options = debugfs_create_dir("options", d_tracer);
4864        if (!t_options) {
4865                pr_warning("Could not create debugfs directory 'options'\n");
4866                return NULL;
4867        }
4868
4869        return t_options;
4870}
4871
4872static void
4873create_trace_option_file(struct trace_option_dentry *topt,
4874                         struct tracer_flags *flags,
4875                         struct tracer_opt *opt)
4876{
4877        struct dentry *t_options;
4878
4879        t_options = trace_options_init_dentry();
4880        if (!t_options)
4881                return;
4882
4883        topt->flags = flags;
4884        topt->opt = opt;
4885
4886        topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
4887                                    &trace_options_fops);
4888
4889}
4890
4891static struct trace_option_dentry *
4892create_trace_option_files(struct tracer *tracer)
4893{
4894        struct trace_option_dentry *topts;
4895        struct tracer_flags *flags;
4896        struct tracer_opt *opts;
4897        int cnt;
4898
4899        if (!tracer)
4900                return NULL;
4901
4902        flags = tracer->flags;
4903
4904        if (!flags || !flags->opts)
4905                return NULL;
4906
4907        opts = flags->opts;
4908
4909        for (cnt = 0; opts[cnt].name; cnt++)
4910                ;
4911
4912        topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
4913        if (!topts)
4914                return NULL;
4915
4916        for (cnt = 0; opts[cnt].name; cnt++)
4917                create_trace_option_file(&topts[cnt], flags,
4918                                         &opts[cnt]);
4919
4920        return topts;
4921}
4922
4923static void
4924destroy_trace_option_files(struct trace_option_dentry *topts)
4925{
4926        int cnt;
4927
4928        if (!topts)
4929                return;
4930
4931        for (cnt = 0; topts[cnt].opt; cnt++) {
4932                if (topts[cnt].entry)
4933                        debugfs_remove(topts[cnt].entry);
4934        }
4935
4936        kfree(topts);
4937}
4938
4939static struct dentry *
4940create_trace_option_core_file(const char *option, long index)
4941{
4942        struct dentry *t_options;
4943
4944        t_options = trace_options_init_dentry();
4945        if (!t_options)
4946                return NULL;
4947
4948        return trace_create_file(option, 0644, t_options, (void *)index,
4949                                    &trace_options_core_fops);
4950}
4951
4952static __init void create_trace_options_dir(void)
4953{
4954        struct dentry *t_options;
4955        int i;
4956
4957        t_options = trace_options_init_dentry();
4958        if (!t_options)
4959                return;
4960
4961        for (i = 0; trace_options[i]; i++)
4962                create_trace_option_core_file(trace_options[i], i);
4963}
4964
4965static ssize_t
4966rb_simple_read(struct file *filp, char __user *ubuf,
4967               size_t cnt, loff_t *ppos)
4968{
4969        struct trace_array *tr = filp->private_data;
4970        struct ring_buffer *buffer = tr->buffer;
4971        char buf[64];
4972        int r;
4973
4974        if (buffer)
4975                r = ring_buffer_record_is_on(buffer);
4976        else
4977                r = 0;
4978
4979        r = sprintf(buf, "%d\n", r);
4980
4981        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
4982}
4983
4984static ssize_t
4985rb_simple_write(struct file *filp, const char __user *ubuf,
4986                size_t cnt, loff_t *ppos)
4987{
4988        struct trace_array *tr = filp->private_data;
4989        struct ring_buffer *buffer = tr->buffer;
4990        unsigned long val;
4991        int ret;
4992
4993        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
4994        if (ret)
4995                return ret;
4996
4997        if (buffer) {
4998                mutex_lock(&trace_types_lock);
4999                if (val) {
5000                        ring_buffer_record_on(buffer);
5001                        if (current_trace->start)
5002                                current_trace->start(tr);
5003                } else {
5004                        ring_buffer_record_off(buffer);
5005                        if (current_trace->stop)
5006                                current_trace->stop(tr);
5007                }
5008                mutex_unlock(&trace_types_lock);
5009        }
5010
5011        (*ppos)++;
5012
5013        return cnt;
5014}
5015
5016static const struct file_operations rb_simple_fops = {
5017        .open           = tracing_open_generic,
5018        .read           = rb_simple_read,
5019        .write          = rb_simple_write,
5020        .llseek         = default_llseek,
5021};
5022
5023static __init int tracer_init_debugfs(void)
5024{
5025        struct dentry *d_tracer;
5026        int cpu;
5027
5028        trace_access_lock_init();
5029
5030        d_tracer = tracing_init_dentry();
5031
5032        trace_create_file("trace_options", 0644, d_tracer,
5033                        NULL, &tracing_iter_fops);
5034
5035        trace_create_file("tracing_cpumask", 0644, d_tracer,
5036                        NULL, &tracing_cpumask_fops);
5037
5038        trace_create_file("trace", 0644, d_tracer,
5039                        (void *) TRACE_PIPE_ALL_CPU, &tracing_fops);
5040
5041        trace_create_file("available_tracers", 0444, d_tracer,
5042                        &global_trace, &show_traces_fops);
5043
5044        trace_create_file("current_tracer", 0644, d_tracer,
5045                        &global_trace, &set_tracer_fops);
5046
5047#ifdef CONFIG_TRACER_MAX_TRACE
5048        trace_create_file("tracing_max_latency", 0644, d_tracer,
5049                        &tracing_max_latency, &tracing_max_lat_fops);
5050#endif
5051
5052        trace_create_file("tracing_thresh", 0644, d_tracer,
5053                        &tracing_thresh, &tracing_max_lat_fops);
5054
5055        trace_create_file("README", 0444, d_tracer,
5056                        NULL, &tracing_readme_fops);
5057
5058        trace_create_file("trace_pipe", 0444, d_tracer,
5059                        (void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);
5060
5061        trace_create_file("buffer_size_kb", 0644, d_tracer,
5062                        (void *) RING_BUFFER_ALL_CPUS, &tracing_entries_fops);
5063
5064        trace_create_file("buffer_total_size_kb", 0444, d_tracer,
5065                        &global_trace, &tracing_total_entries_fops);
5066
5067        trace_create_file("free_buffer", 0644, d_tracer,
5068                        &global_trace, &tracing_free_buffer_fops);
5069
5070        trace_create_file("trace_marker", 0220, d_tracer,
5071                        NULL, &tracing_mark_fops);
5072
5073        trace_create_file("saved_cmdlines", 0444, d_tracer,
5074                        NULL, &tracing_saved_cmdlines_fops);
5075
5076        trace_create_file("trace_clock", 0644, d_tracer, NULL,
5077                          &trace_clock_fops);
5078
5079        trace_create_file("tracing_on", 0644, d_tracer,
5080                            &global_trace, &rb_simple_fops);
5081
5082#ifdef CONFIG_DYNAMIC_FTRACE
5083        trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
5084                        &ftrace_update_tot_cnt, &tracing_dyn_info_fops);
5085#endif
5086
5087#ifdef CONFIG_TRACER_SNAPSHOT
5088        trace_create_file("snapshot", 0644, d_tracer,
5089                          (void *) TRACE_PIPE_ALL_CPU, &snapshot_fops);
5090#endif
5091
5092        create_trace_options_dir();
5093
5094        for_each_tracing_cpu(cpu)
5095                tracing_init_debugfs_percpu(cpu);
5096
5097        return 0;
5098}
5099
5100static int trace_panic_handler(struct notifier_block *this,
5101                               unsigned long event, void *unused)
5102{
5103        if (ftrace_dump_on_oops)
5104                ftrace_dump(ftrace_dump_on_oops);
5105        return NOTIFY_OK;
5106}
5107
5108static struct notifier_block trace_panic_notifier = {
5109        .notifier_call  = trace_panic_handler,
5110        .next           = NULL,
5111        .priority       = 150   /* priority: INT_MAX >= x >= 0 */
5112};
5113
5114static int trace_die_handler(struct notifier_block *self,
5115                             unsigned long val,
5116                             void *data)
5117{
5118        switch (val) {
5119        case DIE_OOPS:
5120                if (ftrace_dump_on_oops)
5121                        ftrace_dump(ftrace_dump_on_oops);
5122                break;
5123        default:
5124                break;
5125        }
5126        return NOTIFY_OK;
5127}
5128
5129static struct notifier_block trace_die_notifier = {
5130        .notifier_call = trace_die_handler,
5131        .priority = 200
5132};
5133
5134/*
5135 * printk is set to max of 1024, we really don't need it that big.
5136 * Nothing should be printing 1000 characters anyway.
5137 */
5138#define TRACE_MAX_PRINT         1000
5139
5140/*
5141 * Define here KERN_TRACE so that we have one place to modify
5142 * it if we decide to change what log level the ftrace dump
5143 * should be at.
5144 */
5145#define KERN_TRACE              KERN_EMERG
5146
5147void
5148trace_printk_seq(struct trace_seq *s)
5149{
5150        /* Probably should print a warning here. */
5151        if (s->len >= 1000)
5152                s->len = 1000;
5153
5154        /* should be zero ended, but we are paranoid. */
5155        s->buffer[s->len] = 0;
5156
5157        printk(KERN_TRACE "%s", s->buffer);
5158
5159        trace_seq_init(s);
5160}
5161
5162void trace_init_global_iter(struct trace_iterator *iter)
5163{
5164        iter->tr = &global_trace;
5165        iter->trace = current_trace;
5166        iter->cpu_file = TRACE_PIPE_ALL_CPU;
5167}
5168
5169static void
5170__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
5171{
5172        static arch_spinlock_t ftrace_dump_lock =
5173                (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
5174        /* use static because iter can be a bit big for the stack */
5175        static struct trace_iterator iter;
5176        unsigned int old_userobj;
5177        static int dump_ran;
5178        unsigned long flags;
5179        int cnt = 0, cpu;
5180
5181        /* only one dump */
5182        local_irq_save(flags);
5183        arch_spin_lock(&ftrace_dump_lock);
5184        if (dump_ran)
5185                goto out;
5186
5187        dump_ran = 1;
5188
5189        tracing_off();
5190
5191        /* Did function tracer already get disabled? */
5192        if (ftrace_is_dead()) {
5193                printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n");
5194                printk("#          MAY BE MISSING FUNCTION EVENTS\n");
5195        }
5196
5197        if (disable_tracing)
5198                ftrace_kill();
5199
5200        /* Simulate the iterator */
5201        trace_init_global_iter(&iter);
5202
5203        for_each_tracing_cpu(cpu) {
5204                atomic_inc(&iter.tr->data[cpu]->disabled);
5205        }
5206
5207        old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
5208
5209        /* don't look at user memory in panic mode */
5210        trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
5211
5212        switch (oops_dump_mode) {
5213        case DUMP_ALL:
5214                iter.cpu_file = TRACE_PIPE_ALL_CPU;
5215                break;
5216        case DUMP_ORIG:
5217                iter.cpu_file = raw_smp_processor_id();
5218                break;
5219        case DUMP_NONE:
5220                goto out_enable;
5221        default:
5222                printk(KERN_TRACE "Bad dumping mode, switching to all CPUs dump\n");
5223                iter.cpu_file = TRACE_PIPE_ALL_CPU;
5224        }
5225
5226        printk(KERN_TRACE "Dumping ftrace buffer:\n");
5227
5228        /*
5229         * We need to stop all tracing on all CPUS to read the
5230         * the next buffer. This is a bit expensive, but is
5231         * not done often. We fill all what we can read,
5232         * and then release the locks again.
5233         */
5234
5235        while (!trace_empty(&iter)) {
5236
5237                if (!cnt)
5238                        printk(KERN_TRACE "---------------------------------\n");
5239
5240                cnt++;
5241
5242                /* reset all but tr, trace, and overruns */
5243                memset(&iter.seq, 0,
5244                       sizeof(struct trace_iterator) -
5245                       offsetof(struct trace_iterator, seq));
5246                iter.iter_flags |= TRACE_FILE_LAT_FMT;
5247                iter.pos = -1;
5248
5249                if (trace_find_next_entry_inc(&iter) != NULL) {
5250                        int ret;
5251
5252                        ret = print_trace_line(&iter);
5253                        if (ret != TRACE_TYPE_NO_CONSUME)
5254                                trace_consume(&iter);
5255                }
5256                touch_nmi_watchdog();
5257
5258                trace_printk_seq(&iter.seq);
5259        }
5260
5261        if (!cnt)
5262                printk(KERN_TRACE "   (ftrace buffer empty)\n");
5263        else
5264                printk(KERN_TRACE "---------------------------------\n");
5265
5266 out_enable:
5267        /* Re-enable tracing if requested */
5268        if (!disable_tracing) {
5269                trace_flags |= old_userobj;
5270
5271                for_each_tracing_cpu(cpu) {
5272                        atomic_dec(&iter.tr->data[cpu]->disabled);
5273                }
5274                tracing_on();
5275        }
5276
5277 out:
5278        arch_spin_unlock(&ftrace_dump_lock);
5279        local_irq_restore(flags);
5280}
5281
5282/* By default: disable tracing after the dump */
5283void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
5284{
5285        __ftrace_dump(true, oops_dump_mode);
5286}
5287EXPORT_SYMBOL_GPL(ftrace_dump);
5288
5289__init static int tracer_alloc_buffers(void)
5290{
5291        int ring_buf_size;
5292        enum ring_buffer_flags rb_flags;
5293        int i;
5294        int ret = -ENOMEM;
5295
5296
5297        if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
5298                goto out;
5299
5300        if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
5301                goto out_free_buffer_mask;
5302
5303        /* Only allocate trace_printk buffers if a trace_printk exists */
5304        if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
5305                /* Must be called before global_trace.buffer is allocated */
5306                trace_printk_init_buffers();
5307
5308        /* To save memory, keep the ring buffer size to its minimum */
5309        if (ring_buffer_expanded)
5310                ring_buf_size = trace_buf_size;
5311        else
5312                ring_buf_size = 1;
5313
5314        rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
5315
5316        cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
5317        cpumask_copy(tracing_cpumask, cpu_all_mask);
5318
5319        /* TODO: make the number of buffers hot pluggable with CPUS */
5320        global_trace.buffer = ring_buffer_alloc(ring_buf_size, rb_flags);
5321        if (!global_trace.buffer) {
5322                printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
5323                WARN_ON(1);
5324                goto out_free_cpumask;
5325        }
5326        if (global_trace.buffer_disabled)
5327                tracing_off();
5328
5329
5330#ifdef CONFIG_TRACER_MAX_TRACE
5331        max_tr.buffer = ring_buffer_alloc(1, rb_flags);
5332        if (!max_tr.buffer) {
5333                printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
5334                WARN_ON(1);
5335                ring_buffer_free(global_trace.buffer);
5336                goto out_free_cpumask;
5337        }
5338#endif
5339
5340        /* Allocate the first page for all buffers */
5341        for_each_tracing_cpu(i) {
5342                global_trace.data[i] = &per_cpu(global_trace_cpu, i);
5343                max_tr.data[i] = &per_cpu(max_tr_data, i);
5344        }
5345
5346        set_buffer_entries(&global_trace,
5347                           ring_buffer_size(global_trace.buffer, 0));
5348#ifdef CONFIG_TRACER_MAX_TRACE
5349        set_buffer_entries(&max_tr, 1);
5350#endif
5351
5352        trace_init_cmdlines();
5353        init_irq_work(&trace_work_wakeup, trace_wake_up);
5354
5355        register_tracer(&nop_trace);
5356
5357        /* All seems OK, enable tracing */
5358        tracing_disabled = 0;
5359
5360        atomic_notifier_chain_register(&panic_notifier_list,
5361                                       &trace_panic_notifier);
5362
5363        register_die_notifier(&trace_die_notifier);
5364
5365        while (trace_boot_options) {
5366                char *option;
5367
5368                option = strsep(&trace_boot_options, ",");
5369                trace_set_options(option);
5370        }
5371
5372        return 0;
5373
5374out_free_cpumask:
5375        free_cpumask_var(tracing_cpumask);
5376out_free_buffer_mask:
5377        free_cpumask_var(tracing_buffer_mask);
5378out:
5379        return ret;
5380}
5381
5382__init static int clear_boot_tracer(void)
5383{
5384        /*
5385         * The default tracer at boot buffer is an init section.
5386         * This function is called in lateinit. If we did not
5387         * find the boot tracer, then clear it out, to prevent
5388         * later registration from accessing the buffer that is
5389         * about to be freed.
5390         */
5391        if (!default_bootup_tracer)
5392                return 0;
5393
5394        printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
5395               default_bootup_tracer);
5396        default_bootup_tracer = NULL;
5397
5398        return 0;
5399}
5400
5401early_initcall(tracer_alloc_buffers);
5402fs_initcall(tracer_init_debugfs);
5403late_initcall(clear_boot_tracer);
5404
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