scripts/recordmcount.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * recordmcount.c: construct a table of the locations of calls to 'mcount'
   4  * so that ftrace can find them quickly.
   5  * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
   6  *
   7  * Restructured to fit Linux format, as well as other updates:
   8  *  Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
   9  */
  10
  11 /*
  12  * Strategy: alter the .o file in-place.
  13  *
  14  * Append a new STRTAB that has the new section names, followed by a new array
  15  * ElfXX_Shdr[] that has the new section headers, followed by the section
  16  * contents for __mcount_loc and its relocations.  The old shstrtab strings,
  17  * and the old ElfXX_Shdr[] array, remain as "garbage" (commonly, a couple
  18  * kilobytes.)  Subsequent processing by /bin/ld (or the kernel module loader)
  19  * will ignore the garbage regions, because they are not designated by the
  20  * new .e_shoff nor the new ElfXX_Shdr[].  [In order to remove the garbage,
  21  * then use "ld -r" to create a new file that omits the garbage.]
  22  */
  23
  24 #include <sys/types.h>
  25 #include <sys/mman.h>
  26 #include <sys/stat.h>
  27 #include <getopt.h>
  28 #include <elf.h>
  29 #include <fcntl.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34
  35 #ifndef EM_AARCH64
  36 #define EM_AARCH64      183
  37 #define R_AARCH64_NONE          0
  38 #define R_AARCH64_ABS64 257
  39 #endif
  40
  41 #define R_ARM_PC24              1
  42 #define R_ARM_THM_CALL          10
  43 #define R_ARM_CALL              28
  44
  45 #define R_AARCH64_CALL26        283
  46
  47 static int fd_map;      /* File descriptor for file being modified. */
  48 static int mmap_failed; /* Boolean flag. */
  49 static char gpfx;       /* prefix for global symbol name (sometimes '_') */
  50 static struct stat sb;  /* Remember .st_size, etc. */
  51 static const char *altmcount;   /* alternate mcount symbol name */
  52 static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
  53 static void *file_map;  /* pointer of the mapped file */
  54 static void *file_end;  /* pointer to the end of the mapped file */
  55 static int file_updated; /* flag to state file was changed */
  56 static void *file_ptr;  /* current file pointer location */
  57
  58 static void *file_append; /* added to the end of the file */
  59 static size_t file_append_size; /* how much is added to end of file */
  60
  61 /* Per-file resource cleanup when multiple files. */
  62 static void file_append_cleanup(void)
  63 {
  64         free(file_append);
  65         file_append = NULL;
  66         file_append_size = 0;
  67         file_updated = 0;
  68 }
  69
  70 static void mmap_cleanup(void)
  71 {
  72         if (!mmap_failed)
  73                 munmap(file_map, sb.st_size);
  74         else
  75                 free(file_map);
  76         file_map = NULL;
  77 }
  78
  79 /* ulseek, uwrite, ...:  Check return value for errors. */
  80
  81 static off_t ulseek(off_t const offset, int const whence)
  82 {
  83         switch (whence) {
  84         case SEEK_SET:
  85                 file_ptr = file_map + offset;
  86                 break;
  87         case SEEK_CUR:
  88                 file_ptr += offset;
  89                 break;
  90         case SEEK_END:
  91                 file_ptr = file_map + (sb.st_size - offset);
  92                 break;
  93         }
  94         if (file_ptr < file_map) {
  95                 fprintf(stderr, "lseek: seek before file\n");
  96                 return -1;
  97         }
  98         return file_ptr - file_map;
  99 }
 100
 101 static ssize_t uwrite(void const *const buf, size_t const count)
 102 {
 103         size_t cnt = count;
 104         off_t idx = 0;
 105
 106         file_updated = 1;
 107
 108         if (file_ptr + count >= file_end) {
 109                 off_t aoffset = (file_ptr + count) - file_end;
 110
 111                 if (aoffset > file_append_size) {
 112                         file_append = realloc(file_append, aoffset);
 113                         file_append_size = aoffset;
 114                 }
 115                 if (!file_append) {
 116                         perror("write");
 117                         file_append_cleanup();
 118                         mmap_cleanup();
 119                         return -1;
 120                 }
 121                 if (file_ptr < file_end) {
 122                         cnt = file_end - file_ptr;
 123                 } else {
 124                         cnt = 0;
 125                         idx = aoffset - count;
 126                 }
 127         }
 128
 129         if (cnt)
 130                 memcpy(file_ptr, buf, cnt);
 131
 132         if (cnt < count)
 133                 memcpy(file_append + idx, buf + cnt, count - cnt);
 134
 135         file_ptr += count;
 136         return count;
 137 }
 138
 139 static void * umalloc(size_t size)
 140 {
 141         void *const addr = malloc(size);
 142         if (addr == 0) {
 143                 fprintf(stderr, "malloc failed: %zu bytes\n", size);
 144                 file_append_cleanup();
 145                 mmap_cleanup();
 146                 return NULL;
 147         }
 148         return addr;
 149 }
 150
 151 /*
 152  * Get the whole file as a programming convenience in order to avoid
 153  * malloc+lseek+read+free of many pieces.  If successful, then mmap
 154  * avoids copying unused pieces; else just read the whole file.
 155  * Open for both read and write; new info will be appended to the file.
 156  * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
 157  * do not propagate to the file until an explicit overwrite at the last.
 158  * This preserves most aspects of consistency (all except .st_size)
 159  * for simultaneous readers of the file while we are appending to it.
 160  * However, multiple writers still are bad.  We choose not to use
 161  * locking because it is expensive and the use case of kernel build
 162  * makes multiple writers unlikely.
 163  */
 164 static void *mmap_file(char const *fname)
 165 {
 166         /* Avoid problems if early cleanup() */
 167         fd_map = -1;
 168         mmap_failed = 1;
 169         file_map = NULL;
 170         file_ptr = NULL;
 171         file_updated = 0;
 172         sb.st_size = 0;
 173
 174         fd_map = open(fname, O_RDONLY);
 175         if (fd_map < 0) {
 176                 perror(fname);
 177                 return NULL;
 178         }
 179         if (fstat(fd_map, &sb) < 0) {
 180                 perror(fname);
 181                 goto out;
 182         }
 183         if (!S_ISREG(sb.st_mode)) {
 184                 fprintf(stderr, "not a regular file: %s\n", fname);
 185                 goto out;
 186         }
 187         file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
 188                         fd_map, 0);
 189         if (file_map == MAP_FAILED) {
 190                 mmap_failed = 1;
 191                 file_map = umalloc(sb.st_size);
 192                 if (!file_map) {
 193                         perror(fname);
 194                         goto out;
 195                 }
 196                 if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
 197                         perror(fname);
 198                         free(file_map);
 199                         file_map = NULL;
 200                         goto out;
 201                 }
 202         } else
 203                 mmap_failed = 0;
 204 out:
 205         close(fd_map);
 206         fd_map = -1;
 207
 208         file_end = file_map + sb.st_size;
 209
 210         return file_map;
 211 }
 212
 213
 214 static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
 215 static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
 216 static unsigned char *ideal_nop;
 217
 218 static char rel_type_nop;
 219
 220 static int (*make_nop)(void *map, size_t const offset);
 221
 222 static int make_nop_x86(void *map, size_t const offset)
 223 {
 224         uint32_t *ptr;
 225         unsigned char *op;
 226
 227         /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
 228         ptr = map + offset;
 229         if (*ptr != 0)
 230                 return -1;
 231
 232         op = map + offset - 1;
 233         if (*op != 0xe8)
 234                 return -1;
 235
 236         /* convert to nop */
 237         if (ulseek(offset - 1, SEEK_SET) < 0)
 238                 return -1;
 239         if (uwrite(ideal_nop, 5) < 0)
 240                 return -1;
 241         return 0;
 242 }
 243
 244 static unsigned char ideal_nop4_arm_le[4] = { 0x00, 0x00, 0xa0, 0xe1 }; /* mov r0, r0 */
 245 static unsigned char ideal_nop4_arm_be[4] = { 0xe1, 0xa0, 0x00, 0x00 }; /* mov r0, r0 */
 246 static unsigned char *ideal_nop4_arm;
 247
 248 static unsigned char bl_mcount_arm_le[4] = { 0xfe, 0xff, 0xff, 0xeb }; /* bl */
 249 static unsigned char bl_mcount_arm_be[4] = { 0xeb, 0xff, 0xff, 0xfe }; /* bl */
 250 static unsigned char *bl_mcount_arm;
 251
 252 static unsigned char push_arm_le[4] = { 0x04, 0xe0, 0x2d, 0xe5 }; /* push {lr} */
 253 static unsigned char push_arm_be[4] = { 0xe5, 0x2d, 0xe0, 0x04 }; /* push {lr} */
 254 static unsigned char *push_arm;
 255
 256 static unsigned char ideal_nop2_thumb_le[2] = { 0x00, 0xbf }; /* nop */
 257 static unsigned char ideal_nop2_thumb_be[2] = { 0xbf, 0x00 }; /* nop */
 258 static unsigned char *ideal_nop2_thumb;
 259
 260 static unsigned char push_bl_mcount_thumb_le[6] = { 0x00, 0xb5, 0xff, 0xf7, 0xfe, 0xff }; /* push {lr}, bl */
 261 static unsigned char push_bl_mcount_thumb_be[6] = { 0xb5, 0x00, 0xf7, 0xff, 0xff, 0xfe }; /* push {lr}, bl */
 262 static unsigned char *push_bl_mcount_thumb;
 263
 264 static int make_nop_arm(void *map, size_t const offset)
 265 {
 266         char *ptr;
 267         int cnt = 1;
 268         int nop_size;
 269         size_t off = offset;
 270
 271         ptr = map + offset;
 272         if (memcmp(ptr, bl_mcount_arm, 4) == 0) {
 273                 if (memcmp(ptr - 4, push_arm, 4) == 0) {
 274                         off -= 4;
 275                         cnt = 2;
 276                 }
 277                 ideal_nop = ideal_nop4_arm;
 278                 nop_size = 4;
 279         } else if (memcmp(ptr - 2, push_bl_mcount_thumb, 6) == 0) {
 280                 cnt = 3;
 281                 nop_size = 2;
 282                 off -= 2;
 283                 ideal_nop = ideal_nop2_thumb;
 284         } else
 285                 return -1;
 286
 287         /* Convert to nop */
 288         if (ulseek(off, SEEK_SET) < 0)
 289                 return -1;
 290
 291         do {
 292                 if (uwrite(ideal_nop, nop_size) < 0)
 293                         return -1;
 294         } while (--cnt > 0);
 295
 296         return 0;
 297 }
 298
 299 static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5};
 300 static int make_nop_arm64(void *map, size_t const offset)
 301 {
 302         uint32_t *ptr;
 303
 304         ptr = map + offset;
 305         /* bl <_mcount> is 0x94000000 before relocation */
 306         if (*ptr != 0x94000000)
 307                 return -1;
 308
 309         /* Convert to nop */
 310         if (ulseek(offset, SEEK_SET) < 0)
 311                 return -1;
 312         if (uwrite(ideal_nop, 4) < 0)
 313                 return -1;
 314         return 0;
 315 }
 316
 317 static int write_file(const char *fname)
 318 {
 319         char tmp_file[strlen(fname) + 4];
 320         size_t n;
 321
 322         if (!file_updated)
 323                 return 0;
 324
 325         sprintf(tmp_file, "%s.rc", fname);
 326
 327         /*
 328          * After reading the entire file into memory, delete it
 329          * and write it back, to prevent weird side effects of modifying
 330          * an object file in place.
 331          */
 332         fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
 333         if (fd_map < 0) {
 334                 perror(fname);
 335                 return -1;
 336         }
 337         n = write(fd_map, file_map, sb.st_size);
 338         if (n != sb.st_size) {
 339                 perror("write");
 340                 close(fd_map);
 341                 return -1;
 342         }
 343         if (file_append_size) {
 344                 n = write(fd_map, file_append, file_append_size);
 345                 if (n != file_append_size) {
 346                         perror("write");
 347                         close(fd_map);
 348                         return -1;
 349                 }
 350         }
 351         close(fd_map);
 352         if (rename(tmp_file, fname) < 0) {
 353                 perror(fname);
 354                 return -1;
 355         }
 356         return 0;
 357 }
 358
 359 /* w8rev, w8nat, ...: Handle endianness. */
 360
 361 static uint64_t w8rev(uint64_t const x)
 362 {
 363         return   ((0xff & (x >> (0 * 8))) << (7 * 8))
 364                | ((0xff & (x >> (1 * 8))) << (6 * 8))
 365                | ((0xff & (x >> (2 * 8))) << (5 * 8))
 366                | ((0xff & (x >> (3 * 8))) << (4 * 8))
 367                | ((0xff & (x >> (4 * 8))) << (3 * 8))
 368                | ((0xff & (x >> (5 * 8))) << (2 * 8))
 369                | ((0xff & (x >> (6 * 8))) << (1 * 8))
 370                | ((0xff & (x >> (7 * 8))) << (0 * 8));
 371 }
 372
 373 static uint32_t w4rev(uint32_t const x)
 374 {
 375         return   ((0xff & (x >> (0 * 8))) << (3 * 8))
 376                | ((0xff & (x >> (1 * 8))) << (2 * 8))
 377                | ((0xff & (x >> (2 * 8))) << (1 * 8))
 378                | ((0xff & (x >> (3 * 8))) << (0 * 8));
 379 }
 380
 381 static uint32_t w2rev(uint16_t const x)
 382 {
 383         return   ((0xff & (x >> (0 * 8))) << (1 * 8))
 384                | ((0xff & (x >> (1 * 8))) << (0 * 8));
 385 }
 386
 387 static uint64_t w8nat(uint64_t const x)
 388 {
 389         return x;
 390 }
 391
 392 static uint32_t w4nat(uint32_t const x)
 393 {
 394         return x;
 395 }
 396
 397 static uint32_t w2nat(uint16_t const x)
 398 {
 399         return x;
 400 }
 401
 402 static uint64_t (*w8)(uint64_t);
 403 static uint32_t (*w)(uint32_t);
 404 static uint32_t (*w2)(uint16_t);
 405
 406 /* Names of the sections that could contain calls to mcount. */
 407 static int is_mcounted_section_name(char const *const txtname)
 408 {
 409         return strncmp(".text",          txtname, 5) == 0 ||
 410                 strcmp(".init.text",     txtname) == 0 ||
 411                 strcmp(".ref.text",      txtname) == 0 ||
 412                 strcmp(".sched.text",    txtname) == 0 ||
 413                 strcmp(".spinlock.text", txtname) == 0 ||
 414                 strcmp(".irqentry.text", txtname) == 0 ||
 415                 strcmp(".softirqentry.text", txtname) == 0 ||
 416                 strcmp(".kprobes.text", txtname) == 0 ||
 417                 strcmp(".cpuidle.text", txtname) == 0;
 418 }
 419
 420 static char const *already_has_rel_mcount = "success"; /* our work here is done! */
 421
 422 /* 32 bit and 64 bit are very similar */
 423 #include "recordmcount.h"
 424 #define RECORD_MCOUNT_64
 425 #include "recordmcount.h"
 426
 427 static int arm_is_fake_mcount(Elf32_Rel const *rp)
 428 {
 429         switch (ELF32_R_TYPE(w(rp->r_info))) {
 430         case R_ARM_THM_CALL:
 431         case R_ARM_CALL:
 432         case R_ARM_PC24:
 433                 return 0;
 434         }
 435
 436         return 1;
 437 }
 438
 439 static int arm64_is_fake_mcount(Elf64_Rel const *rp)
 440 {
 441         return ELF64_R_TYPE(w8(rp->r_info)) != R_AARCH64_CALL26;
 442 }
 443
 444 /* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
 445  * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
 446  * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
 447  * to imply the order of the members; the spec does not say so.
 448  *      typedef unsigned char Elf64_Byte;
 449  * fails on MIPS64 because their <elf.h> already has it!
 450  */
 451
 452 typedef uint8_t myElf64_Byte;           /* Type for a 8-bit quantity.  */
 453
 454 union mips_r_info {
 455         Elf64_Xword r_info;
 456         struct {
 457                 Elf64_Word r_sym;               /* Symbol index.  */
 458                 myElf64_Byte r_ssym;            /* Special symbol.  */
 459                 myElf64_Byte r_type3;           /* Third relocation.  */
 460                 myElf64_Byte r_type2;           /* Second relocation.  */
 461                 myElf64_Byte r_type;            /* First relocation.  */
 462         } r_mips;
 463 };
 464
 465 static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
 466 {
 467         return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
 468 }
 469
 470 static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
 471 {
 472         rp->r_info = ((union mips_r_info){
 473                 .r_mips = { .r_sym = w(sym), .r_type = type }
 474         }).r_info;
 475 }
 476
 477 static int do_file(char const *const fname)
 478 {
 479         unsigned int reltype = 0;
 480         Elf32_Ehdr *ehdr;
 481         int rc = -1;
 482
 483         ehdr = mmap_file(fname);
 484         if (!ehdr)
 485                 goto out;
 486
 487         w = w4nat;
 488         w2 = w2nat;
 489         w8 = w8nat;
 490         switch (ehdr->e_ident[EI_DATA]) {
 491                 static unsigned int const endian = 1;
 492         default:
 493                 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 494                         ehdr->e_ident[EI_DATA], fname);
 495                 goto out;
 496         case ELFDATA2LSB:
 497                 if (*(unsigned char const *)&endian != 1) {
 498                         /* main() is big endian, file.o is little endian. */
 499                         w = w4rev;
 500                         w2 = w2rev;
 501                         w8 = w8rev;
 502                 }
 503                 ideal_nop4_arm = ideal_nop4_arm_le;
 504                 bl_mcount_arm = bl_mcount_arm_le;
 505                 push_arm = push_arm_le;
 506                 ideal_nop2_thumb = ideal_nop2_thumb_le;
 507                 push_bl_mcount_thumb = push_bl_mcount_thumb_le;
 508                 break;
 509         case ELFDATA2MSB:
 510                 if (*(unsigned char const *)&endian != 0) {
 511                         /* main() is little endian, file.o is big endian. */
 512                         w = w4rev;
 513                         w2 = w2rev;
 514                         w8 = w8rev;
 515                 }
 516                 ideal_nop4_arm = ideal_nop4_arm_be;
 517                 bl_mcount_arm = bl_mcount_arm_be;
 518                 push_arm = push_arm_be;
 519                 ideal_nop2_thumb = ideal_nop2_thumb_be;
 520                 push_bl_mcount_thumb = push_bl_mcount_thumb_be;
 521                 break;
 522         }  /* end switch */
 523         if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0 ||
 524             w2(ehdr->e_type) != ET_REL ||
 525             ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 526                 fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
 527                 goto out;
 528         }
 529
 530         gpfx = '_';
 531         switch (w2(ehdr->e_machine)) {
 532         default:
 533                 fprintf(stderr, "unrecognized e_machine %u %s\n",
 534                         w2(ehdr->e_machine), fname);
 535                 goto out;
 536         case EM_386:
 537                 reltype = R_386_32;
 538                 rel_type_nop = R_386_NONE;
 539                 make_nop = make_nop_x86;
 540                 ideal_nop = ideal_nop5_x86_32;
 541                 mcount_adjust_32 = -1;
 542                 gpfx = 0;
 543                 break;
 544         case EM_ARM:
 545                 reltype = R_ARM_ABS32;
 546                 altmcount = "__gnu_mcount_nc";
 547                 make_nop = make_nop_arm;
 548                 rel_type_nop = R_ARM_NONE;
 549                 is_fake_mcount32 = arm_is_fake_mcount;
 550                 gpfx = 0;
 551                 break;
 552         case EM_AARCH64:
 553                 reltype = R_AARCH64_ABS64;
 554                 make_nop = make_nop_arm64;
 555                 rel_type_nop = R_AARCH64_NONE;
 556                 ideal_nop = ideal_nop4_arm64;
 557                 is_fake_mcount64 = arm64_is_fake_mcount;
 558                 break;
 559         case EM_IA_64:  reltype = R_IA64_IMM64; break;
 560         case EM_MIPS:   /* reltype: e_class    */ break;
 561         case EM_PPC:    reltype = R_PPC_ADDR32; break;
 562         case EM_PPC64:  reltype = R_PPC64_ADDR64; break;
 563         case EM_S390:   /* reltype: e_class    */ break;
 564         case EM_SH:     reltype = R_SH_DIR32; gpfx = 0; break;
 565         case EM_SPARCV9: reltype = R_SPARC_64; break;
 566         case EM_X86_64:
 567                 make_nop = make_nop_x86;
 568                 ideal_nop = ideal_nop5_x86_64;
 569                 reltype = R_X86_64_64;
 570                 rel_type_nop = R_X86_64_NONE;
 571                 mcount_adjust_64 = -1;
 572                 gpfx = 0;
 573                 break;
 574         }  /* end switch */
 575
 576         switch (ehdr->e_ident[EI_CLASS]) {
 577         default:
 578                 fprintf(stderr, "unrecognized ELF class %d %s\n",
 579                         ehdr->e_ident[EI_CLASS], fname);
 580                 goto out;
 581         case ELFCLASS32:
 582                 if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 583                 ||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 584                         fprintf(stderr,
 585                                 "unrecognized ET_REL file: %s\n", fname);
 586                         goto out;
 587                 }
 588                 if (w2(ehdr->e_machine) == EM_MIPS) {
 589                         reltype = R_MIPS_32;
 590                         is_fake_mcount32 = MIPS32_is_fake_mcount;
 591                 }
 592                 if (do32(ehdr, fname, reltype) < 0)
 593                         goto out;
 594                 break;
 595         case ELFCLASS64: {
 596                 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
 597                 if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
 598                 ||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 599                         fprintf(stderr,
 600                                 "unrecognized ET_REL file: %s\n", fname);
 601                         goto out;
 602                 }
 603                 if (w2(ghdr->e_machine) == EM_S390) {
 604                         reltype = R_390_64;
 605                         mcount_adjust_64 = -14;
 606                 }
 607                 if (w2(ghdr->e_machine) == EM_MIPS) {
 608                         reltype = R_MIPS_64;
 609                         Elf64_r_sym = MIPS64_r_sym;
 610                         Elf64_r_info = MIPS64_r_info;
 611                         is_fake_mcount64 = MIPS64_is_fake_mcount;
 612                 }
 613                 if (do64(ghdr, fname, reltype) < 0)
 614                         goto out;
 615                 break;
 616         }
 617         }  /* end switch */
 618
 619         rc = write_file(fname);
 620 out:
 621         file_append_cleanup();
 622         mmap_cleanup();
 623         return rc;
 624 }
 625
 626 int main(int argc, char *argv[])
 627 {
 628         const char ftrace[] = "/ftrace.o";
 629         int ftrace_size = sizeof(ftrace) - 1;
 630         int n_error = 0;  /* gcc-4.3.0 false positive complaint */
 631         int c;
 632         int i;
 633
 634         while ((c = getopt(argc, argv, "w")) >= 0) {
 635                 switch (c) {
 636                 case 'w':
 637                         warn_on_notrace_sect = 1;
 638                         break;
 639                 default:
 640                         fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
 641                         return 0;
 642                 }
 643         }
 644
 645         if ((argc - optind) < 1) {
 646                 fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
 647                 return 0;
 648         }
 649
 650         /* Process each file in turn, allowing deep failure. */
 651         for (i = optind; i < argc; i++) {
 652                 char *file = argv[i];
 653                 int len;
 654
 655                 /*
 656                  * The file kernel/trace/ftrace.o references the mcount
 657                  * function but does not call it. Since ftrace.o should
 658                  * not be traced anyway, we just skip it.
 659                  */
 660                 len = strlen(file);
 661                 if (len >= ftrace_size &&
 662                     strcmp(file + (len - ftrace_size), ftrace) == 0)
 663                         continue;
 664
 665                 if (do_file(file)) {
 666                         fprintf(stderr, "%s: failed\n", file);
 667                         ++n_error;
 668                 }
 669         }
 670         return !!n_error;
 671 }