linux/kernel/panic.c
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   1/*
   2 *  linux/kernel/panic.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7/*
   8 * This function is used through-out the kernel (including mm and fs)
   9 * to indicate a major problem.
  10 */
  11#include <linux/debug_locks.h>
  12#include <linux/interrupt.h>
  13#include <linux/kmsg_dump.h>
  14#include <linux/kallsyms.h>
  15#include <linux/notifier.h>
  16#include <linux/module.h>
  17#include <linux/random.h>
  18#include <linux/reboot.h>
  19#include <linux/delay.h>
  20#include <linux/kexec.h>
  21#include <linux/sched.h>
  22#include <linux/sysrq.h>
  23#include <linux/init.h>
  24#include <linux/nmi.h>
  25#include <linux/dmi.h>
  26
  27#define PANIC_TIMER_STEP 100
  28#define PANIC_BLINK_SPD 18
  29
  30int panic_on_oops;
  31static unsigned long tainted_mask;
  32static int pause_on_oops;
  33static int pause_on_oops_flag;
  34static DEFINE_SPINLOCK(pause_on_oops_lock);
  35
  36int panic_timeout;
  37EXPORT_SYMBOL_GPL(panic_timeout);
  38
  39ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
  40
  41EXPORT_SYMBOL(panic_notifier_list);
  42
  43static long no_blink(int state)
  44{
  45        return 0;
  46}
  47
  48/* Returns how long it waited in ms */
  49long (*panic_blink)(int state);
  50EXPORT_SYMBOL(panic_blink);
  51
  52/**
  53 *      panic - halt the system
  54 *      @fmt: The text string to print
  55 *
  56 *      Display a message, then perform cleanups.
  57 *
  58 *      This function never returns.
  59 */
  60NORET_TYPE void panic(const char * fmt, ...)
  61{
  62        static char buf[1024];
  63        va_list args;
  64        long i, i_next = 0;
  65        int state = 0;
  66
  67        /*
  68         * It's possible to come here directly from a panic-assertion and
  69         * not have preempt disabled. Some functions called from here want
  70         * preempt to be disabled. No point enabling it later though...
  71         */
  72        preempt_disable();
  73
  74        console_verbose();
  75        bust_spinlocks(1);
  76        va_start(args, fmt);
  77        vsnprintf(buf, sizeof(buf), fmt, args);
  78        va_end(args);
  79        printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
  80#ifdef CONFIG_DEBUG_BUGVERBOSE
  81        dump_stack();
  82#endif
  83
  84        /*
  85         * If we have crashed and we have a crash kernel loaded let it handle
  86         * everything else.
  87         * Do we want to call this before we try to display a message?
  88         */
  89        crash_kexec(NULL);
  90
  91        kmsg_dump(KMSG_DUMP_PANIC);
  92
  93        /*
  94         * Note smp_send_stop is the usual smp shutdown function, which
  95         * unfortunately means it may not be hardened to work in a panic
  96         * situation.
  97         */
  98        smp_send_stop();
  99
 100        atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 101
 102        bust_spinlocks(0);
 103
 104        if (!panic_blink)
 105                panic_blink = no_blink;
 106
 107        if (panic_timeout > 0) {
 108                /*
 109                 * Delay timeout seconds before rebooting the machine.
 110                 * We can't use the "normal" timers since we just panicked.
 111                 */
 112                printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
 113
 114                for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
 115                        touch_nmi_watchdog();
 116                        if (i >= i_next) {
 117                                i += panic_blink(state ^= 1);
 118                                i_next = i + 3600 / PANIC_BLINK_SPD;
 119                        }
 120                        mdelay(PANIC_TIMER_STEP);
 121                }
 122        }
 123        if (panic_timeout != 0) {
 124                /*
 125                 * This will not be a clean reboot, with everything
 126                 * shutting down.  But if there is a chance of
 127                 * rebooting the system it will be rebooted.
 128                 */
 129                emergency_restart();
 130        }
 131#ifdef __sparc__
 132        {
 133                extern int stop_a_enabled;
 134                /* Make sure the user can actually press Stop-A (L1-A) */
 135                stop_a_enabled = 1;
 136                printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
 137        }
 138#endif
 139#if defined(CONFIG_S390)
 140        {
 141                unsigned long caller;
 142
 143                caller = (unsigned long)__builtin_return_address(0);
 144                disabled_wait(caller);
 145        }
 146#endif
 147        local_irq_enable();
 148        for (i = 0; ; i += PANIC_TIMER_STEP) {
 149                touch_softlockup_watchdog();
 150                if (i >= i_next) {
 151                        i += panic_blink(state ^= 1);
 152                        i_next = i + 3600 / PANIC_BLINK_SPD;
 153                }
 154                mdelay(PANIC_TIMER_STEP);
 155        }
 156}
 157
 158EXPORT_SYMBOL(panic);
 159
 160
 161struct tnt {
 162        u8      bit;
 163        char    true;
 164        char    false;
 165};
 166
 167static const struct tnt tnts[] = {
 168        { TAINT_PROPRIETARY_MODULE,     'P', 'G' },
 169        { TAINT_FORCED_MODULE,          'F', ' ' },
 170        { TAINT_UNSAFE_SMP,             'S', ' ' },
 171        { TAINT_FORCED_RMMOD,           'R', ' ' },
 172        { TAINT_MACHINE_CHECK,          'M', ' ' },
 173        { TAINT_BAD_PAGE,               'B', ' ' },
 174        { TAINT_USER,                   'U', ' ' },
 175        { TAINT_DIE,                    'D', ' ' },
 176        { TAINT_OVERRIDDEN_ACPI_TABLE,  'A', ' ' },
 177        { TAINT_WARN,                   'W', ' ' },
 178        { TAINT_CRAP,                   'C', ' ' },
 179        { TAINT_FIRMWARE_WORKAROUND,    'I', ' ' },
 180};
 181
 182/**
 183 *      print_tainted - return a string to represent the kernel taint state.
 184 *
 185 *  'P' - Proprietary module has been loaded.
 186 *  'F' - Module has been forcibly loaded.
 187 *  'S' - SMP with CPUs not designed for SMP.
 188 *  'R' - User forced a module unload.
 189 *  'M' - System experienced a machine check exception.
 190 *  'B' - System has hit bad_page.
 191 *  'U' - Userspace-defined naughtiness.
 192 *  'D' - Kernel has oopsed before
 193 *  'A' - ACPI table overridden.
 194 *  'W' - Taint on warning.
 195 *  'C' - modules from drivers/staging are loaded.
 196 *  'I' - Working around severe firmware bug.
 197 *
 198 *      The string is overwritten by the next call to print_tainted().
 199 */
 200const char *print_tainted(void)
 201{
 202        static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
 203
 204        if (tainted_mask) {
 205                char *s;
 206                int i;
 207
 208                s = buf + sprintf(buf, "Tainted: ");
 209                for (i = 0; i < ARRAY_SIZE(tnts); i++) {
 210                        const struct tnt *t = &tnts[i];
 211                        *s++ = test_bit(t->bit, &tainted_mask) ?
 212                                        t->true : t->false;
 213                }
 214                *s = 0;
 215        } else
 216                snprintf(buf, sizeof(buf), "Not tainted");
 217
 218        return buf;
 219}
 220
 221int test_taint(unsigned flag)
 222{
 223        return test_bit(flag, &tainted_mask);
 224}
 225EXPORT_SYMBOL(test_taint);
 226
 227unsigned long get_taint(void)
 228{
 229        return tainted_mask;
 230}
 231
 232void add_taint(unsigned flag)
 233{
 234        /*
 235         * Can't trust the integrity of the kernel anymore.
 236         * We don't call directly debug_locks_off() because the issue
 237         * is not necessarily serious enough to set oops_in_progress to 1
 238         * Also we want to keep up lockdep for staging development and
 239         * post-warning case.
 240         */
 241        if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
 242                printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
 243
 244        set_bit(flag, &tainted_mask);
 245}
 246EXPORT_SYMBOL(add_taint);
 247
 248static void spin_msec(int msecs)
 249{
 250        int i;
 251
 252        for (i = 0; i < msecs; i++) {
 253                touch_nmi_watchdog();
 254                mdelay(1);
 255        }
 256}
 257
 258/*
 259 * It just happens that oops_enter() and oops_exit() are identically
 260 * implemented...
 261 */
 262static void do_oops_enter_exit(void)
 263{
 264        unsigned long flags;
 265        static int spin_counter;
 266
 267        if (!pause_on_oops)
 268                return;
 269
 270        spin_lock_irqsave(&pause_on_oops_lock, flags);
 271        if (pause_on_oops_flag == 0) {
 272                /* This CPU may now print the oops message */
 273                pause_on_oops_flag = 1;
 274        } else {
 275                /* We need to stall this CPU */
 276                if (!spin_counter) {
 277                        /* This CPU gets to do the counting */
 278                        spin_counter = pause_on_oops;
 279                        do {
 280                                spin_unlock(&pause_on_oops_lock);
 281                                spin_msec(MSEC_PER_SEC);
 282                                spin_lock(&pause_on_oops_lock);
 283                        } while (--spin_counter);
 284                        pause_on_oops_flag = 0;
 285                } else {
 286                        /* This CPU waits for a different one */
 287                        while (spin_counter) {
 288                                spin_unlock(&pause_on_oops_lock);
 289                                spin_msec(1);
 290                                spin_lock(&pause_on_oops_lock);
 291                        }
 292                }
 293        }
 294        spin_unlock_irqrestore(&pause_on_oops_lock, flags);
 295}
 296
 297/*
 298 * Return true if the calling CPU is allowed to print oops-related info.
 299 * This is a bit racy..
 300 */
 301int oops_may_print(void)
 302{
 303        return pause_on_oops_flag == 0;
 304}
 305
 306/*
 307 * Called when the architecture enters its oops handler, before it prints
 308 * anything.  If this is the first CPU to oops, and it's oopsing the first
 309 * time then let it proceed.
 310 *
 311 * This is all enabled by the pause_on_oops kernel boot option.  We do all
 312 * this to ensure that oopses don't scroll off the screen.  It has the
 313 * side-effect of preventing later-oopsing CPUs from mucking up the display,
 314 * too.
 315 *
 316 * It turns out that the CPU which is allowed to print ends up pausing for
 317 * the right duration, whereas all the other CPUs pause for twice as long:
 318 * once in oops_enter(), once in oops_exit().
 319 */
 320void oops_enter(void)
 321{
 322        tracing_off();
 323        /* can't trust the integrity of the kernel anymore: */
 324        debug_locks_off();
 325        do_oops_enter_exit();
 326}
 327
 328/*
 329 * 64-bit random ID for oopses:
 330 */
 331static u64 oops_id;
 332
 333static int init_oops_id(void)
 334{
 335        if (!oops_id)
 336                get_random_bytes(&oops_id, sizeof(oops_id));
 337        else
 338                oops_id++;
 339
 340        return 0;
 341}
 342late_initcall(init_oops_id);
 343
 344void print_oops_end_marker(void)
 345{
 346        init_oops_id();
 347        printk(KERN_WARNING "---[ end trace %016llx ]---\n",
 348                (unsigned long long)oops_id);
 349}
 350
 351/*
 352 * Called when the architecture exits its oops handler, after printing
 353 * everything.
 354 */
 355void oops_exit(void)
 356{
 357        do_oops_enter_exit();
 358        print_oops_end_marker();
 359        kmsg_dump(KMSG_DUMP_OOPS);
 360}
 361
 362#ifdef WANT_WARN_ON_SLOWPATH
 363struct slowpath_args {
 364        const char *fmt;
 365        va_list args;
 366};
 367
 368static void warn_slowpath_common(const char *file, int line, void *caller,
 369                                 unsigned taint, struct slowpath_args *args)
 370{
 371        const char *board;
 372
 373        printk(KERN_WARNING "------------[ cut here ]------------\n");
 374        printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
 375        board = dmi_get_system_info(DMI_PRODUCT_NAME);
 376        if (board)
 377                printk(KERN_WARNING "Hardware name: %s\n", board);
 378
 379        if (args)
 380                vprintk(args->fmt, args->args);
 381
 382        print_modules();
 383        dump_stack();
 384        print_oops_end_marker();
 385        add_taint(taint);
 386}
 387
 388void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 389{
 390        struct slowpath_args args;
 391
 392        args.fmt = fmt;
 393        va_start(args.args, fmt);
 394        warn_slowpath_common(file, line, __builtin_return_address(0),
 395                             TAINT_WARN, &args);
 396        va_end(args.args);
 397}
 398EXPORT_SYMBOL(warn_slowpath_fmt);
 399
 400void warn_slowpath_fmt_taint(const char *file, int line,
 401                             unsigned taint, const char *fmt, ...)
 402{
 403        struct slowpath_args args;
 404
 405        args.fmt = fmt;
 406        va_start(args.args, fmt);
 407        warn_slowpath_common(file, line, __builtin_return_address(0),
 408                             taint, &args);
 409        va_end(args.args);
 410}
 411EXPORT_SYMBOL(warn_slowpath_fmt_taint);
 412
 413void warn_slowpath_null(const char *file, int line)
 414{
 415        warn_slowpath_common(file, line, __builtin_return_address(0),
 416                             TAINT_WARN, NULL);
 417}
 418EXPORT_SYMBOL(warn_slowpath_null);
 419#endif
 420
 421#ifdef CONFIG_CC_STACKPROTECTOR
 422
 423/*
 424 * Called when gcc's -fstack-protector feature is used, and
 425 * gcc detects corruption of the on-stack canary value
 426 */
 427void __stack_chk_fail(void)
 428{
 429        panic("stack-protector: Kernel stack is corrupted in: %p\n",
 430                __builtin_return_address(0));
 431}
 432EXPORT_SYMBOL(__stack_chk_fail);
 433
 434#endif
 435
 436core_param(panic, panic_timeout, int, 0644);
 437core_param(pause_on_oops, pause_on_oops, int, 0644);
 438
 439static int __init oops_setup(char *s)
 440{
 441        if (!s)
 442                return -EINVAL;
 443        if (!strcmp(s, "panic"))
 444                panic_on_oops = 1;
 445        return 0;
 446}
 447early_param("oops", oops_setup);
 448
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