tools/perf/tests/code-reading.c

   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 "evlist.h"
  20 #include "evsel.h"
  21 #include "thread_map.h"
  22 #include "machine.h"
  23 #include "map.h"
  24 #include "symbol.h"
  25 #include "event.h"
  26 #include "record.h"
  27 #include "util/mmap.h"
  28 #include "util/string2.h"
  29 #include "util/synthetic-events.h"
  30 #include "util/util.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
  40 struct state {
  41         u64 done[1024];
  42         size_t done_cnt;
  43 };
  44
  45 static 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 && !host_is_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
  98 static 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
 127 static 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
 179 static 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, test_objdump_path, 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
 216 static 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
 228 static 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] = {0};
 233         unsigned char buf2[BUFSZ] = {0};
 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, err = 0;
 240         struct dso *dso;
 241
 242         pr_debug("Reading object code for memory address: %#"PRIx64"\n", addr);
 243
 244         addr_location__init(&al);
 245         if (!thread__find_map(thread, cpumode, addr, &al) || !map__dso(al.map)) {
 246                 if (cpumode == PERF_RECORD_MISC_HYPERVISOR) {
 247                         pr_debug("Hypervisor address can not be resolved - skipping\n");
 248                         goto out;
 249                 }
 250
 251                 pr_debug("thread__find_map failed\n");
 252                 err = -1;
 253                 goto out;
 254         }
 255         dso = map__dso(al.map);
 256         pr_debug("File is: %s\n", dso__long_name(dso));
 257
 258         if (dso__symtab_type(dso) == DSO_BINARY_TYPE__KALLSYMS && !dso__is_kcore(dso)) {
 259                 pr_debug("Unexpected kernel address - skipping\n");
 260                 goto out;
 261         }
 262
 263         pr_debug("On file address is: %#"PRIx64"\n", al.addr);
 264
 265         if (len > BUFSZ)
 266                 len = BUFSZ;
 267
 268         /* Do not go off the map */
 269         if (addr + len > map__end(al.map))
 270                 len = map__end(al.map) - addr;
 271
 272         /*
 273          * Some architectures (ex: powerpc) have stubs (trampolines) in kernel
 274          * modules to manage long jumps. Check if the ip offset falls in stubs
 275          * sections for kernel modules. And skip module address after text end
 276          */
 277         if (dso__is_kmod(dso) && al.addr > dso__text_end(dso)) {
 278                 pr_debug("skipping the module address %#"PRIx64" after text end\n", al.addr);
 279                 goto out;
 280         }
 281
 282         /* Read the object code using perf */
 283         ret_len = dso__data_read_offset(dso, maps__machine(thread__maps(thread)),
 284                                         al.addr, buf1, len);
 285         if (ret_len != len) {
 286                 pr_debug("dso__data_read_offset failed\n");
 287                 err = -1;
 288                 goto out;
 289         }
 290
 291         /*
 292          * Converting addresses for use by objdump requires more information.
 293          * map__load() does that.  See map__rip_2objdump() for details.
 294          */
 295         if (map__load(al.map)) {
 296                 err = -1;
 297                 goto out;
 298         }
 299
 300         /* objdump struggles with kcore - try each map only once */
 301         if (dso__is_kcore(dso)) {
 302                 size_t d;
 303
 304                 for (d = 0; d < state->done_cnt; d++) {
 305                         if (state->done[d] == map__start(al.map)) {
 306                                 pr_debug("kcore map tested already");
 307                                 pr_debug(" - skipping\n");
 308                                 goto out;
 309                         }
 310                 }
 311                 if (state->done_cnt >= ARRAY_SIZE(state->done)) {
 312                         pr_debug("Too many kcore maps - skipping\n");
 313                         goto out;
 314                 }
 315                 state->done[state->done_cnt++] = map__start(al.map);
 316         }
 317
 318         objdump_name = dso__long_name(dso);
 319         if (dso__needs_decompress(dso)) {
 320                 if (dso__decompress_kmodule_path(dso, objdump_name,
 321                                                  decomp_name,
 322                                                  sizeof(decomp_name)) < 0) {
 323                         pr_debug("decompression failed\n");
 324                         err = -1;
 325                         goto out;
 326                 }
 327
 328                 decomp = true;
 329                 objdump_name = decomp_name;
 330         }
 331
 332         /* Read the object code using objdump */
 333         objdump_addr = map__rip_2objdump(al.map, al.addr);
 334         ret = read_via_objdump(objdump_name, objdump_addr, buf2, len);
 335
 336         if (decomp)
 337                 unlink(objdump_name);
 338
 339         if (ret > 0) {
 340                 /*
 341                  * The kernel maps are inaccurate - assume objdump is right in
 342                  * that case.
 343                  */
 344                 if (cpumode == PERF_RECORD_MISC_KERNEL ||
 345                     cpumode == PERF_RECORD_MISC_GUEST_KERNEL) {
 346                         len -= ret;
 347                         if (len) {
 348                                 pr_debug("Reducing len to %zu\n", len);
 349                         } else if (dso__is_kcore(dso)) {
 350                                 /*
 351                                  * objdump cannot handle very large segments
 352                                  * that may be found in kcore.
 353                                  */
 354                                 pr_debug("objdump failed for kcore");
 355                                 pr_debug(" - skipping\n");
 356                         } else {
 357                                 err = -1;
 358                         }
 359                         goto out;
 360                 }
 361         }
 362         if (ret < 0) {
 363                 pr_debug("read_via_objdump failed\n");
 364                 err = -1;
 365                 goto out;
 366         }
 367
 368         /* The results should be identical */
 369         if (memcmp(buf1, buf2, len)) {
 370                 pr_debug("Bytes read differ from those read by objdump\n");
 371                 pr_debug("buf1 (dso):\n");
 372                 dump_buf(buf1, len);
 373                 pr_debug("buf2 (objdump):\n");
 374                 dump_buf(buf2, len);
 375                 err = -1;
 376                 goto out;
 377         }
 378         pr_debug("Bytes read match those read by objdump\n");
 379 out:
 380         addr_location__exit(&al);
 381         return err;
 382 }
 383
 384 static int process_sample_event(struct machine *machine,
 385                                 struct evlist *evlist,
 386                                 union perf_event *event, struct state *state)
 387 {
 388         struct perf_sample sample;
 389         struct thread *thread;
 390         int ret;
 391
 392         if (evlist__parse_sample(evlist, event, &sample)) {
 393                 pr_debug("evlist__parse_sample failed\n");
 394                 return -1;
 395         }
 396
 397         thread = machine__findnew_thread(machine, sample.pid, sample.tid);
 398         if (!thread) {
 399                 pr_debug("machine__findnew_thread failed\n");
 400                 return -1;
 401         }
 402
 403         ret = read_object_code(sample.ip, READLEN, sample.cpumode, thread, state);
 404         thread__put(thread);
 405         return ret;
 406 }
 407
 408 static int process_event(struct machine *machine, struct evlist *evlist,
 409                          union perf_event *event, struct state *state)
 410 {
 411         if (event->header.type == PERF_RECORD_SAMPLE)
 412                 return process_sample_event(machine, evlist, event, state);
 413
 414         if (event->header.type == PERF_RECORD_THROTTLE ||
 415             event->header.type == PERF_RECORD_UNTHROTTLE)
 416                 return 0;
 417
 418         if (event->header.type < PERF_RECORD_MAX) {
 419                 int ret;
 420
 421                 ret = machine__process_event(machine, event, NULL);
 422                 if (ret < 0)
 423                         pr_debug("machine__process_event failed, event type %u\n",
 424                                  event->header.type);
 425                 return ret;
 426         }
 427
 428         return 0;
 429 }
 430
 431 static int process_events(struct machine *machine, struct evlist *evlist,
 432                           struct state *state)
 433 {
 434         union perf_event *event;
 435         struct mmap *md;
 436         int i, ret;
 437
 438         for (i = 0; i < evlist->core.nr_mmaps; i++) {
 439                 md = &evlist->mmap[i];
 440                 if (perf_mmap__read_init(&md->core) < 0)
 441                         continue;
 442
 443                 while ((event = perf_mmap__read_event(&md->core)) != NULL) {
 444                         ret = process_event(machine, evlist, event, state);
 445                         perf_mmap__consume(&md->core);
 446                         if (ret < 0)
 447                                 return ret;
 448                 }
 449                 perf_mmap__read_done(&md->core);
 450         }
 451         return 0;
 452 }
 453
 454 static int comp(const void *a, const void *b)
 455 {
 456         return *(int *)a - *(int *)b;
 457 }
 458
 459 static void do_sort_something(void)
 460 {
 461         int buf[40960], i;
 462
 463         for (i = 0; i < (int)ARRAY_SIZE(buf); i++)
 464                 buf[i] = ARRAY_SIZE(buf) - i - 1;
 465
 466         qsort(buf, ARRAY_SIZE(buf), sizeof(int), comp);
 467
 468         for (i = 0; i < (int)ARRAY_SIZE(buf); i++) {
 469                 if (buf[i] != i) {
 470                         pr_debug("qsort failed\n");
 471                         break;
 472                 }
 473         }
 474 }
 475
 476 static void sort_something(void)
 477 {
 478         int i;
 479
 480         for (i = 0; i < 10; i++)
 481                 do_sort_something();
 482 }
 483
 484 static void syscall_something(void)
 485 {
 486         int pipefd[2];
 487         int i;
 488
 489         for (i = 0; i < 1000; i++) {
 490                 if (pipe(pipefd) < 0) {
 491                         pr_debug("pipe failed\n");
 492                         break;
 493                 }
 494                 close(pipefd[1]);
 495                 close(pipefd[0]);
 496         }
 497 }
 498
 499 static void fs_something(void)
 500 {
 501         const char *test_file_name = "temp-perf-code-reading-test-file--";
 502         FILE *f;
 503         int i;
 504
 505         for (i = 0; i < 1000; i++) {
 506                 f = fopen(test_file_name, "w+");
 507                 if (f) {
 508                         fclose(f);
 509                         unlink(test_file_name);
 510                 }
 511         }
 512 }
 513
 514 static void do_something(void)
 515 {
 516         fs_something();
 517
 518         sort_something();
 519
 520         syscall_something();
 521 }
 522
 523 enum {
 524         TEST_CODE_READING_OK,
 525         TEST_CODE_READING_NO_VMLINUX,
 526         TEST_CODE_READING_NO_KCORE,
 527         TEST_CODE_READING_NO_ACCESS,
 528         TEST_CODE_READING_NO_KERNEL_OBJ,
 529 };
 530
 531 static int do_test_code_reading(bool try_kcore)
 532 {
 533         struct machine *machine;
 534         struct thread *thread;
 535         struct record_opts opts = {
 536                 .mmap_pages          = UINT_MAX,
 537                 .user_freq           = UINT_MAX,
 538                 .user_interval       = ULLONG_MAX,
 539                 .freq                = 500,
 540                 .target              = {
 541                         .uses_mmap   = true,
 542                 },
 543         };
 544         struct state state = {
 545                 .done_cnt = 0,
 546         };
 547         struct perf_thread_map *threads = NULL;
 548         struct perf_cpu_map *cpus = NULL;
 549         struct evlist *evlist = NULL;
 550         struct evsel *evsel = NULL;
 551         int err = -1, ret;
 552         pid_t pid;
 553         struct map *map;
 554         bool have_vmlinux, have_kcore;
 555         struct dso *dso;
 556         const char *events[] = { "cycles", "cycles:u", "cpu-clock", "cpu-clock:u", NULL };
 557         int evidx = 0;
 558
 559         pid = getpid();
 560
 561         machine = machine__new_host();
 562         machine->env = &perf_env;
 563
 564         ret = machine__create_kernel_maps(machine);
 565         if (ret < 0) {
 566                 pr_debug("machine__create_kernel_maps failed\n");
 567                 goto out_err;
 568         }
 569
 570         /* Force the use of kallsyms instead of vmlinux to try kcore */
 571         if (try_kcore)
 572                 symbol_conf.kallsyms_name = "/proc/kallsyms";
 573
 574         /* Load kernel map */
 575         map = machine__kernel_map(machine);
 576         ret = map__load(map);
 577         if (ret < 0) {
 578                 pr_debug("map__load failed\n");
 579                 goto out_err;
 580         }
 581         dso = map__dso(map);
 582         have_vmlinux = dso__is_vmlinux(dso);
 583         have_kcore = dso__is_kcore(dso);
 584
 585         /* 2nd time through we just try kcore */
 586         if (try_kcore && !have_kcore)
 587                 return TEST_CODE_READING_NO_KCORE;
 588
 589         /* No point getting kernel events if there is no kernel object */
 590         if (!have_vmlinux && !have_kcore)
 591                 evidx++;
 592
 593         threads = thread_map__new_by_tid(pid);
 594         if (!threads) {
 595                 pr_debug("thread_map__new_by_tid failed\n");
 596                 goto out_err;
 597         }
 598
 599         ret = perf_event__synthesize_thread_map(NULL, threads,
 600                                                 perf_event__process, machine,
 601                                                 true, false);
 602         if (ret < 0) {
 603                 pr_debug("perf_event__synthesize_thread_map failed\n");
 604                 goto out_err;
 605         }
 606
 607         thread = machine__findnew_thread(machine, pid, pid);
 608         if (!thread) {
 609                 pr_debug("machine__findnew_thread failed\n");
 610                 goto out_put;
 611         }
 612
 613         cpus = perf_cpu_map__new_online_cpus();
 614         if (!cpus) {
 615                 pr_debug("perf_cpu_map__new failed\n");
 616                 goto out_put;
 617         }
 618
 619         while (events[evidx]) {
 620                 const char *str;
 621
 622                 evlist = evlist__new();
 623                 if (!evlist) {
 624                         pr_debug("evlist__new failed\n");
 625                         goto out_put;
 626                 }
 627
 628                 perf_evlist__set_maps(&evlist->core, cpus, threads);
 629
 630                 str = events[evidx];
 631                 pr_debug("Parsing event '%s'\n", str);
 632                 ret = parse_event(evlist, str);
 633                 if (ret < 0) {
 634                         pr_debug("parse_events failed\n");
 635                         goto out_put;
 636                 }
 637
 638                 evlist__config(evlist, &opts, NULL);
 639
 640                 evlist__for_each_entry(evlist, evsel) {
 641                         evsel->core.attr.comm = 1;
 642                         evsel->core.attr.disabled = 1;
 643                         evsel->core.attr.enable_on_exec = 0;
 644                 }
 645
 646                 ret = evlist__open(evlist);
 647                 if (ret < 0) {
 648                         evidx++;
 649
 650                         if (events[evidx] == NULL && verbose > 0) {
 651                                 char errbuf[512];
 652                                 evlist__strerror_open(evlist, errno, errbuf, sizeof(errbuf));
 653                                 pr_debug("perf_evlist__open() failed!\n%s\n", errbuf);
 654                         }
 655
 656                         /*
 657                          * Both cpus and threads are now owned by evlist
 658                          * and will be freed by following perf_evlist__set_maps
 659                          * call. Getting reference to keep them alive.
 660                          */
 661                         perf_cpu_map__get(cpus);
 662                         perf_thread_map__get(threads);
 663                         perf_evlist__set_maps(&evlist->core, NULL, NULL);
 664                         evlist__delete(evlist);
 665                         evlist = NULL;
 666                         continue;
 667                 }
 668                 break;
 669         }
 670
 671         if (events[evidx] == NULL)
 672                 goto out_put;
 673
 674         ret = evlist__mmap(evlist, UINT_MAX);
 675         if (ret < 0) {
 676                 pr_debug("evlist__mmap failed\n");
 677                 goto out_put;
 678         }
 679
 680         evlist__enable(evlist);
 681
 682         do_something();
 683
 684         evlist__disable(evlist);
 685
 686         ret = process_events(machine, evlist, &state);
 687         if (ret < 0)
 688                 goto out_put;
 689
 690         if (!have_vmlinux && !have_kcore && !try_kcore)
 691                 err = TEST_CODE_READING_NO_KERNEL_OBJ;
 692         else if (!have_vmlinux && !try_kcore)
 693                 err = TEST_CODE_READING_NO_VMLINUX;
 694         else if (strstr(events[evidx], ":u"))
 695                 err = TEST_CODE_READING_NO_ACCESS;
 696         else
 697                 err = TEST_CODE_READING_OK;
 698 out_put:
 699         thread__put(thread);
 700 out_err:
 701         evlist__delete(evlist);
 702         perf_cpu_map__put(cpus);
 703         perf_thread_map__put(threads);
 704         machine__delete(machine);
 705
 706         return err;
 707 }
 708
 709 static int test__code_reading(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
 710 {
 711         int ret;
 712
 713         ret = do_test_code_reading(false);
 714         if (!ret)
 715                 ret = do_test_code_reading(true);
 716
 717         switch (ret) {
 718         case TEST_CODE_READING_OK:
 719                 return 0;
 720         case TEST_CODE_READING_NO_VMLINUX:
 721                 pr_debug("no vmlinux\n");
 722                 return 0;
 723         case TEST_CODE_READING_NO_KCORE:
 724                 pr_debug("no kcore\n");
 725                 return 0;
 726         case TEST_CODE_READING_NO_ACCESS:
 727                 pr_debug("no access\n");
 728                 return 0;
 729         case TEST_CODE_READING_NO_KERNEL_OBJ:
 730                 pr_debug("no kernel obj\n");
 731                 return 0;
 732         default:
 733                 return -1;
 734         };
 735 }
 736
 737 DEFINE_SUITE("Object code reading", code_reading);