linux/tools/perf/tests/code-reading.c
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   1// SPDX-License-Identifier: GPL-2.0
   2#include <errno.h>
   3#include <linux/kernel.h>
   4#include <linux/types.h>
   5#include <inttypes.h>
   6#include <stdlib.h>
   7#include <unistd.h>
   8#include <stdio.h>
   9#include <string.h>
  10#include <sys/param.h>
  11#include <perf/cpumap.h>
  12#include <perf/evlist.h>
  13#include <perf/mmap.h>
  14
  15#include "debug.h"
  16#include "dso.h"
  17#include "env.h"
  18#include "parse-events.h"
  19#include "trace-event.h"
  20#include "evlist.h"
  21#include "evsel.h"
  22#include "thread_map.h"
  23#include "machine.h"
  24#include "map.h"
  25#include "symbol.h"
  26#include "event.h"
  27#include "record.h"
  28#include "util/mmap.h"
  29#include "util/string2.h"
  30#include "util/synthetic-events.h"
  31#include "thread.h"
  32
  33#include "tests.h"
  34
  35#include <linux/ctype.h>
  36
  37#define BUFSZ   1024
  38#define READLEN 128
  39
  40struct state {
  41        u64 done[1024];
  42        size_t done_cnt;
  43};
  44
  45static size_t read_objdump_chunk(const char **line, unsigned char **buf,
  46                                 size_t *buf_len)
  47{
  48        size_t bytes_read = 0;
  49        unsigned char *chunk_start = *buf;
  50
  51        /* Read bytes */
  52        while (*buf_len > 0) {
  53                char c1, c2;
  54
  55                /* Get 2 hex digits */
  56                c1 = *(*line)++;
  57                if (!isxdigit(c1))
  58                        break;
  59                c2 = *(*line)++;
  60                if (!isxdigit(c2))
  61                        break;
  62
  63                /* Store byte and advance buf */
  64                **buf = (hex(c1) << 4) | hex(c2);
  65                (*buf)++;
  66                (*buf_len)--;
  67                bytes_read++;
  68
  69                /* End of chunk? */
  70                if (isspace(**line))
  71                        break;
  72        }
  73
  74        /*
  75         * objdump will display raw insn as LE if code endian
  76         * is LE and bytes_per_chunk > 1. In that case reverse
  77         * the chunk we just read.
  78         *
  79         * see disassemble_bytes() at binutils/objdump.c for details
  80         * how objdump chooses display endian)
  81         */
  82        if (bytes_read > 1 && !bigendian()) {
  83                unsigned char *chunk_end = chunk_start + bytes_read - 1;
  84                unsigned char tmp;
  85
  86                while (chunk_start < chunk_end) {
  87                        tmp = *chunk_start;
  88                        *chunk_start = *chunk_end;
  89                        *chunk_end = tmp;
  90                        chunk_start++;
  91                        chunk_end--;
  92                }
  93        }
  94
  95        return bytes_read;
  96}
  97
  98static size_t read_objdump_line(const char *line, unsigned char *buf,
  99                                size_t buf_len)
 100{
 101        const char *p;
 102        size_t ret, bytes_read = 0;
 103
 104        /* Skip to a colon */
 105        p = strchr(line, ':');
 106        if (!p)
 107                return 0;
 108        p++;
 109
 110        /* Skip initial spaces */
 111        while (*p) {
 112                if (!isspace(*p))
 113                        break;
 114                p++;
 115        }
 116
 117        do {
 118                ret = read_objdump_chunk(&p, &buf, &buf_len);
 119                bytes_read += ret;
 120                p++;
 121        } while (ret > 0);
 122
 123        /* return number of successfully read bytes */
 124        return bytes_read;
 125}
 126
 127static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)
 128{
 129        char *line = NULL;
 130        size_t line_len, off_last = 0;
 131        ssize_t ret;
 132        int err = 0;
 133        u64 addr, last_addr = start_addr;
 134
 135        while (off_last < *len) {
 136                size_t off, read_bytes, written_bytes;
 137                unsigned char tmp[BUFSZ];
 138
 139                ret = getline(&line, &line_len, f);
 140                if (feof(f))
 141                        break;
 142                if (ret < 0) {
 143                        pr_debug("getline failed\n");
 144                        err = -1;
 145                        break;
 146                }
 147
 148                /* read objdump data into temporary buffer */
 149                read_bytes = read_objdump_line(line, tmp, sizeof(tmp));
 150                if (!read_bytes)
 151                        continue;
 152
 153                if (sscanf(line, "%"PRIx64, &addr) != 1)
 154                        continue;
 155                if (addr < last_addr) {
 156                        pr_debug("addr going backwards, read beyond section?\n");
 157                        break;
 158                }
 159                last_addr = addr;
 160
 161                /* copy it from temporary buffer to 'buf' according
 162                 * to address on current objdump line */
 163                off = addr - start_addr;
 164                if (off >= *len)
 165                        break;
 166                written_bytes = MIN(read_bytes, *len - off);
 167                memcpy(buf + off, tmp, written_bytes);
 168                off_last = off + written_bytes;
 169        }
 170
 171        /* len returns number of bytes that could not be read */
 172        *len -= off_last;
 173
 174        free(line);
 175
 176        return err;
 177}
 178
 179static int read_via_objdump(const char *filename, u64 addr, void *buf,
 180                            size_t len)
 181{
 182        char cmd[PATH_MAX * 2];
 183        const char *fmt;
 184        FILE *f;
 185        int ret;
 186
 187        fmt = "%s -z -d --start-address=0x%"PRIx64" --stop-address=0x%"PRIx64" %s";
 188        ret = snprintf(cmd, sizeof(cmd), fmt, "objdump", addr, addr + len,
 189                       filename);
 190        if (ret <= 0 || (size_t)ret >= sizeof(cmd))
 191                return -1;
 192
 193        pr_debug("Objdump command is: %s\n", cmd);
 194
 195        /* Ignore objdump errors */
 196        strcat(cmd, " 2>/dev/null");
 197
 198        f = popen(cmd, "r");
 199        if (!f) {
 200                pr_debug("popen failed\n");
 201                return -1;
 202        }
 203
 204        ret = read_objdump_output(f, buf, &len, addr);
 205        if (len) {
 206                pr_debug("objdump read too few bytes: %zd\n", len);
 207                if (!ret)
 208                        ret = len;
 209        }
 210
 211        pclose(f);
 212
 213        return ret;
 214}
 215
 216static void dump_buf(unsigned char *buf, size_t len)
 217{
 218        size_t i;
 219
 220        for (i = 0; i < len; i++) {
 221                pr_debug("0x%02x ", buf[i]);
 222                if (i % 16 == 15)
 223                        pr_debug("\n");
 224        }
 225        pr_debug("\n");
 226}
 227
 228static int read_object_code(u64 addr, size_t len, u8 cpumode,
 229                            struct thread *thread, struct state *state)
 230{
 231        struct addr_location al;
 232        unsigned char buf1[BUFSZ];
 233        unsigned char buf2[BUFSZ];
 234        size_t ret_len;
 235        u64 objdump_addr;
 236        const char *objdump_name;
 237        char decomp_name[KMOD_DECOMP_LEN];
 238        bool decomp = false;
 239        int ret;
 240
 241        pr_debug("Reading object code for memory address: %#"PRIx64"\n", addr);
 242
 243        if (!thread__find_map(thread, cpumode, addr, &al) || !al.map->dso) {
 244                if (cpumode == PERF_RECORD_MISC_HYPERVISOR) {
 245                        pr_debug("Hypervisor address can not be resolved - skipping\n");
 246                        return 0;
 247                }
 248
 249                pr_debug("thread__find_map failed\n");
 250                return -1;
 251        }
 252
 253        pr_debug("File is: %s\n", al.map->dso->long_name);
 254
 255        if (al.map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
 256            !dso__is_kcore(al.map->dso)) {
 257                pr_debug("Unexpected kernel address - skipping\n");
 258                return 0;
 259        }
 260
 261        pr_debug("On file address is: %#"PRIx64"\n", al.addr);
 262
 263        if (len > BUFSZ)
 264                len = BUFSZ;
 265
 266        /* Do not go off the map */
 267        if (addr + len > al.map->end)
 268                len = al.map->end - addr;
 269
 270        /* Read the object code using perf */
 271        ret_len = dso__data_read_offset(al.map->dso, thread->maps->machine,
 272                                        al.addr, buf1, len);
 273        if (ret_len != len) {
 274                pr_debug("dso__data_read_offset failed\n");
 275                return -1;
 276        }
 277
 278        /*
 279         * Converting addresses for use by objdump requires more information.
 280         * map__load() does that.  See map__rip_2objdump() for details.
 281         */
 282        if (map__load(al.map))
 283                return -1;
 284
 285        /* objdump struggles with kcore - try each map only once */
 286        if (dso__is_kcore(al.map->dso)) {
 287                size_t d;
 288
 289                for (d = 0; d < state->done_cnt; d++) {
 290                        if (state->done[d] == al.map->start) {
 291                                pr_debug("kcore map tested already");
 292                                pr_debug(" - skipping\n");
 293                                return 0;
 294                        }
 295                }
 296                if (state->done_cnt >= ARRAY_SIZE(state->done)) {
 297                        pr_debug("Too many kcore maps - skipping\n");
 298                        return 0;
 299                }
 300                state->done[state->done_cnt++] = al.map->start;
 301        }
 302
 303        objdump_name = al.map->dso->long_name;
 304        if (dso__needs_decompress(al.map->dso)) {
 305                if (dso__decompress_kmodule_path(al.map->dso, objdump_name,
 306                                                 decomp_name,
 307                                                 sizeof(decomp_name)) < 0) {
 308                        pr_debug("decompression failed\n");
 309                        return -1;
 310                }
 311
 312                decomp = true;
 313                objdump_name = decomp_name;
 314        }
 315
 316        /* Read the object code using objdump */
 317        objdump_addr = map__rip_2objdump(al.map, al.addr);
 318        ret = read_via_objdump(objdump_name, objdump_addr, buf2, len);
 319
 320        if (decomp)
 321                unlink(objdump_name);
 322
 323        if (ret > 0) {
 324                /*
 325                 * The kernel maps are inaccurate - assume objdump is right in
 326                 * that case.
 327                 */
 328                if (cpumode == PERF_RECORD_MISC_KERNEL ||
 329                    cpumode == PERF_RECORD_MISC_GUEST_KERNEL) {
 330                        len -= ret;
 331                        if (len) {
 332                                pr_debug("Reducing len to %zu\n", len);
 333                        } else if (dso__is_kcore(al.map->dso)) {
 334                                /*
 335                                 * objdump cannot handle very large segments
 336                                 * that may be found in kcore.
 337                                 */
 338                                pr_debug("objdump failed for kcore");
 339                                pr_debug(" - skipping\n");
 340                                return 0;
 341                        } else {
 342                                return -1;
 343                        }
 344                }
 345        }
 346        if (ret < 0) {
 347                pr_debug("read_via_objdump failed\n");
 348                return -1;
 349        }
 350
 351        /* The results should be identical */
 352        if (memcmp(buf1, buf2, len)) {
 353                pr_debug("Bytes read differ from those read by objdump\n");
 354                pr_debug("buf1 (dso):\n");
 355                dump_buf(buf1, len);
 356                pr_debug("buf2 (objdump):\n");
 357                dump_buf(buf2, len);
 358                return -1;
 359        }
 360        pr_debug("Bytes read match those read by objdump\n");
 361
 362        return 0;
 363}
 364
 365static int process_sample_event(struct machine *machine,
 366                                struct evlist *evlist,
 367                                union perf_event *event, struct state *state)
 368{
 369        struct perf_sample sample;
 370        struct thread *thread;
 371        int ret;
 372
 373        if (evlist__parse_sample(evlist, event, &sample)) {
 374                pr_debug("evlist__parse_sample failed\n");
 375                return -1;
 376        }
 377
 378        thread = machine__findnew_thread(machine, sample.pid, sample.tid);
 379        if (!thread) {
 380                pr_debug("machine__findnew_thread failed\n");
 381                return -1;
 382        }
 383
 384        ret = read_object_code(sample.ip, READLEN, sample.cpumode, thread, state);
 385        thread__put(thread);
 386        return ret;
 387}
 388
 389static int process_event(struct machine *machine, struct evlist *evlist,
 390                         union perf_event *event, struct state *state)
 391{
 392        if (event->header.type == PERF_RECORD_SAMPLE)
 393                return process_sample_event(machine, evlist, event, state);
 394
 395        if (event->header.type == PERF_RECORD_THROTTLE ||
 396            event->header.type == PERF_RECORD_UNTHROTTLE)
 397                return 0;
 398
 399        if (event->header.type < PERF_RECORD_MAX) {
 400                int ret;
 401
 402                ret = machine__process_event(machine, event, NULL);
 403                if (ret < 0)
 404                        pr_debug("machine__process_event failed, event type %u\n",
 405                                 event->header.type);
 406                return ret;
 407        }
 408
 409        return 0;
 410}
 411
 412static int process_events(struct machine *machine, struct evlist *evlist,
 413                          struct state *state)
 414{
 415        union perf_event *event;
 416        struct mmap *md;
 417        int i, ret;
 418
 419        for (i = 0; i < evlist->core.nr_mmaps; i++) {
 420                md = &evlist->mmap[i];
 421                if (perf_mmap__read_init(&md->core) < 0)
 422                        continue;
 423
 424                while ((event = perf_mmap__read_event(&md->core)) != NULL) {
 425                        ret = process_event(machine, evlist, event, state);
 426                        perf_mmap__consume(&md->core);
 427                        if (ret < 0)
 428                                return ret;
 429                }
 430                perf_mmap__read_done(&md->core);
 431        }
 432        return 0;
 433}
 434
 435static int comp(const void *a, const void *b)
 436{
 437        return *(int *)a - *(int *)b;
 438}
 439
 440static void do_sort_something(void)
 441{
 442        int buf[40960], i;
 443
 444        for (i = 0; i < (int)ARRAY_SIZE(buf); i++)
 445                buf[i] = ARRAY_SIZE(buf) - i - 1;
 446
 447        qsort(buf, ARRAY_SIZE(buf), sizeof(int), comp);
 448
 449        for (i = 0; i < (int)ARRAY_SIZE(buf); i++) {
 450                if (buf[i] != i) {
 451                        pr_debug("qsort failed\n");
 452                        break;
 453                }
 454        }
 455}
 456
 457static void sort_something(void)
 458{
 459        int i;
 460
 461        for (i = 0; i < 10; i++)
 462                do_sort_something();
 463}
 464
 465static void syscall_something(void)
 466{
 467        int pipefd[2];
 468        int i;
 469
 470        for (i = 0; i < 1000; i++) {
 471                if (pipe(pipefd) < 0) {
 472                        pr_debug("pipe failed\n");
 473                        break;
 474                }
 475                close(pipefd[1]);
 476                close(pipefd[0]);
 477        }
 478}
 479
 480static void fs_something(void)
 481{
 482        const char *test_file_name = "temp-perf-code-reading-test-file--";
 483        FILE *f;
 484        int i;
 485
 486        for (i = 0; i < 1000; i++) {
 487                f = fopen(test_file_name, "w+");
 488                if (f) {
 489                        fclose(f);
 490                        unlink(test_file_name);
 491                }
 492        }
 493}
 494
 495#ifdef __s390x__
 496#include "header.h" // for get_cpuid()
 497#endif
 498
 499static const char *do_determine_event(bool excl_kernel)
 500{
 501        const char *event = excl_kernel ? "cycles:u" : "cycles";
 502
 503#ifdef __s390x__
 504        char cpuid[128], model[16], model_c[16], cpum_cf_v[16];
 505        unsigned int family;
 506        int ret, cpum_cf_a;
 507
 508        if (get_cpuid(cpuid, sizeof(cpuid)))
 509                goto out_clocks;
 510        ret = sscanf(cpuid, "%*[^,],%u,%[^,],%[^,],%[^,],%x", &family, model_c,
 511                     model, cpum_cf_v, &cpum_cf_a);
 512        if (ret != 5)            /* Not available */
 513                goto out_clocks;
 514        if (excl_kernel && (cpum_cf_a & 4))
 515                return event;
 516        if (!excl_kernel && (cpum_cf_a & 2))
 517                return event;
 518
 519        /* Fall through: missing authorization */
 520out_clocks:
 521        event = excl_kernel ? "cpu-clock:u" : "cpu-clock";
 522
 523#endif
 524        return event;
 525}
 526
 527static void do_something(void)
 528{
 529        fs_something();
 530
 531        sort_something();
 532
 533        syscall_something();
 534}
 535
 536enum {
 537        TEST_CODE_READING_OK,
 538        TEST_CODE_READING_NO_VMLINUX,
 539        TEST_CODE_READING_NO_KCORE,
 540        TEST_CODE_READING_NO_ACCESS,
 541        TEST_CODE_READING_NO_KERNEL_OBJ,
 542};
 543
 544static int do_test_code_reading(bool try_kcore)
 545{
 546        struct machine *machine;
 547        struct thread *thread;
 548        struct record_opts opts = {
 549                .mmap_pages          = UINT_MAX,
 550                .user_freq           = UINT_MAX,
 551                .user_interval       = ULLONG_MAX,
 552                .freq                = 500,
 553                .target              = {
 554                        .uses_mmap   = true,
 555                },
 556        };
 557        struct state state = {
 558                .done_cnt = 0,
 559        };
 560        struct perf_thread_map *threads = NULL;
 561        struct perf_cpu_map *cpus = NULL;
 562        struct evlist *evlist = NULL;
 563        struct evsel *evsel = NULL;
 564        int err = -1, ret;
 565        pid_t pid;
 566        struct map *map;
 567        bool have_vmlinux, have_kcore, excl_kernel = false;
 568
 569        pid = getpid();
 570
 571        machine = machine__new_host();
 572        machine->env = &perf_env;
 573
 574        ret = machine__create_kernel_maps(machine);
 575        if (ret < 0) {
 576                pr_debug("machine__create_kernel_maps failed\n");
 577                goto out_err;
 578        }
 579
 580        /* Force the use of kallsyms instead of vmlinux to try kcore */
 581        if (try_kcore)
 582                symbol_conf.kallsyms_name = "/proc/kallsyms";
 583
 584        /* Load kernel map */
 585        map = machine__kernel_map(machine);
 586        ret = map__load(map);
 587        if (ret < 0) {
 588                pr_debug("map__load failed\n");
 589                goto out_err;
 590        }
 591        have_vmlinux = dso__is_vmlinux(map->dso);
 592        have_kcore = dso__is_kcore(map->dso);
 593
 594        /* 2nd time through we just try kcore */
 595        if (try_kcore && !have_kcore)
 596                return TEST_CODE_READING_NO_KCORE;
 597
 598        /* No point getting kernel events if there is no kernel object */
 599        if (!have_vmlinux && !have_kcore)
 600                excl_kernel = true;
 601
 602        threads = thread_map__new_by_tid(pid);
 603        if (!threads) {
 604                pr_debug("thread_map__new_by_tid failed\n");
 605                goto out_err;
 606        }
 607
 608        ret = perf_event__synthesize_thread_map(NULL, threads,
 609                                                perf_event__process, machine, false);
 610        if (ret < 0) {
 611                pr_debug("perf_event__synthesize_thread_map failed\n");
 612                goto out_err;
 613        }
 614
 615        thread = machine__findnew_thread(machine, pid, pid);
 616        if (!thread) {
 617                pr_debug("machine__findnew_thread failed\n");
 618                goto out_put;
 619        }
 620
 621        cpus = perf_cpu_map__new(NULL);
 622        if (!cpus) {
 623                pr_debug("perf_cpu_map__new failed\n");
 624                goto out_put;
 625        }
 626
 627        while (1) {
 628                const char *str;
 629
 630                evlist = evlist__new();
 631                if (!evlist) {
 632                        pr_debug("evlist__new failed\n");
 633                        goto out_put;
 634                }
 635
 636                perf_evlist__set_maps(&evlist->core, cpus, threads);
 637
 638                str = do_determine_event(excl_kernel);
 639                pr_debug("Parsing event '%s'\n", str);
 640                ret = parse_events(evlist, str, NULL);
 641                if (ret < 0) {
 642                        pr_debug("parse_events failed\n");
 643                        goto out_put;
 644                }
 645
 646                evlist__config(evlist, &opts, NULL);
 647
 648                evsel = evlist__first(evlist);
 649
 650                evsel->core.attr.comm = 1;
 651                evsel->core.attr.disabled = 1;
 652                evsel->core.attr.enable_on_exec = 0;
 653
 654                ret = evlist__open(evlist);
 655                if (ret < 0) {
 656                        if (!excl_kernel) {
 657                                excl_kernel = true;
 658                                /*
 659                                 * Both cpus and threads are now owned by evlist
 660                                 * and will be freed by following perf_evlist__set_maps
 661                                 * call. Getting reference to keep them alive.
 662                                 */
 663                                perf_cpu_map__get(cpus);
 664                                perf_thread_map__get(threads);
 665                                perf_evlist__set_maps(&evlist->core, NULL, NULL);
 666                                evlist__delete(evlist);
 667                                evlist = NULL;
 668                                continue;
 669                        }
 670
 671                        if (verbose > 0) {
 672                                char errbuf[512];
 673                                evlist__strerror_open(evlist, errno, errbuf, sizeof(errbuf));
 674                                pr_debug("perf_evlist__open() failed!\n%s\n", errbuf);
 675                        }
 676
 677                        goto out_put;
 678                }
 679                break;
 680        }
 681
 682        ret = evlist__mmap(evlist, UINT_MAX);
 683        if (ret < 0) {
 684                pr_debug("evlist__mmap failed\n");
 685                goto out_put;
 686        }
 687
 688        evlist__enable(evlist);
 689
 690        do_something();
 691
 692        evlist__disable(evlist);
 693
 694        ret = process_events(machine, evlist, &state);
 695        if (ret < 0)
 696                goto out_put;
 697
 698        if (!have_vmlinux && !have_kcore && !try_kcore)
 699                err = TEST_CODE_READING_NO_KERNEL_OBJ;
 700        else if (!have_vmlinux && !try_kcore)
 701                err = TEST_CODE_READING_NO_VMLINUX;
 702        else if (excl_kernel)
 703                err = TEST_CODE_READING_NO_ACCESS;
 704        else
 705                err = TEST_CODE_READING_OK;
 706out_put:
 707        thread__put(thread);
 708out_err:
 709        evlist__delete(evlist);
 710        perf_cpu_map__put(cpus);
 711        perf_thread_map__put(threads);
 712        machine__delete_threads(machine);
 713        machine__delete(machine);
 714
 715        return err;
 716}
 717
 718int test__code_reading(struct test *test __maybe_unused, int subtest __maybe_unused)
 719{
 720        int ret;
 721
 722        ret = do_test_code_reading(false);
 723        if (!ret)
 724                ret = do_test_code_reading(true);
 725
 726        switch (ret) {
 727        case TEST_CODE_READING_OK:
 728                return 0;
 729        case TEST_CODE_READING_NO_VMLINUX:
 730                pr_debug("no vmlinux\n");
 731                return 0;
 732        case TEST_CODE_READING_NO_KCORE:
 733                pr_debug("no kcore\n");
 734                return 0;
 735        case TEST_CODE_READING_NO_ACCESS:
 736                pr_debug("no access\n");
 737                return 0;
 738        case TEST_CODE_READING_NO_KERNEL_OBJ:
 739                pr_debug("no kernel obj\n");
 740                return 0;
 741        default:
 742                return -1;
 743        };
 744}
 745
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