scripts/recordmcount.c

   1 /*
   2  * recordmcount.c: construct a table of the locations of calls to 'mcount'
   3  * so that ftrace can find them quickly.
   4  * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
   5  * Licensed under the GNU General Public License, version 2 (GPLv2).
   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 <setjmp.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35
  36 /*
  37  * glibc synced up and added the metag number but didn't add the relocations.
  38  * Work around this in a crude manner for now.
  39  */
  40 #ifndef EM_METAG
  41 #define EM_METAG      174
  42 #endif
  43 #ifndef R_METAG_ADDR32
  44 #define R_METAG_ADDR32                   2
  45 #endif
  46 #ifndef R_METAG_NONE
  47 #define R_METAG_NONE                     3
  48 #endif
  49
  50 #ifndef EM_AARCH64
  51 #define EM_AARCH64      183
  52 #define R_AARCH64_NONE          0
  53 #define R_AARCH64_ABS64 257
  54 #endif
  55
  56 static int fd_map;      /* File descriptor for file being modified. */
  57 static int mmap_failed; /* Boolean flag. */
  58 static char gpfx;       /* prefix for global symbol name (sometimes '_') */
  59 static struct stat sb;  /* Remember .st_size, etc. */
  60 static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */
  61 static const char *altmcount;   /* alternate mcount symbol name */
  62 static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
  63 static void *file_map;  /* pointer of the mapped file */
  64 static void *file_end;  /* pointer to the end of the mapped file */
  65 static int file_updated; /* flag to state file was changed */
  66 static void *file_ptr;  /* current file pointer location */
  67 static void *file_append; /* added to the end of the file */
  68 static size_t file_append_size; /* how much is added to end of file */
  69
  70 /* setjmp() return values */
  71 enum {
  72         SJ_SETJMP = 0,  /* hardwired first return */
  73         SJ_FAIL,
  74         SJ_SUCCEED
  75 };
  76
  77 /* Per-file resource cleanup when multiple files. */
  78 static void
  79 cleanup(void)
  80 {
  81         if (!mmap_failed)
  82                 munmap(file_map, sb.st_size);
  83         else
  84                 free(file_map);
  85         file_map = NULL;
  86         free(file_append);
  87         file_append = NULL;
  88         file_append_size = 0;
  89         file_updated = 0;
  90 }
  91
  92 static void __attribute__((noreturn))
  93 fail_file(void)
  94 {
  95         cleanup();
  96         longjmp(jmpenv, SJ_FAIL);
  97 }
  98
  99 static void __attribute__((noreturn))
 100 succeed_file(void)
 101 {
 102         cleanup();
 103         longjmp(jmpenv, SJ_SUCCEED);
 104 }
 105
 106 /* ulseek, uread, ...:  Check return value for errors. */
 107
 108 static off_t
 109 ulseek(int const fd, off_t const offset, int const whence)
 110 {
 111         switch (whence) {
 112         case SEEK_SET:
 113                 file_ptr = file_map + offset;
 114                 break;
 115         case SEEK_CUR:
 116                 file_ptr += offset;
 117                 break;
 118         case SEEK_END:
 119                 file_ptr = file_map + (sb.st_size - offset);
 120                 break;
 121         }
 122         if (file_ptr < file_map) {
 123                 fprintf(stderr, "lseek: seek before file\n");
 124                 fail_file();
 125         }
 126         return file_ptr - file_map;
 127 }
 128
 129 static size_t
 130 uread(int const fd, void *const buf, size_t const count)
 131 {
 132         size_t const n = read(fd, buf, count);
 133         if (n != count) {
 134                 perror("read");
 135                 fail_file();
 136         }
 137         return n;
 138 }
 139
 140 static size_t
 141 uwrite(int const fd, void const *const buf, size_t const count)
 142 {
 143         size_t cnt = count;
 144         off_t idx = 0;
 145
 146         file_updated = 1;
 147
 148         if (file_ptr + count >= file_end) {
 149                 off_t aoffset = (file_ptr + count) - file_end;
 150
 151                 if (aoffset > file_append_size) {
 152                         file_append = realloc(file_append, aoffset);
 153                         file_append_size = aoffset;
 154                 }
 155                 if (!file_append) {
 156                         perror("write");
 157                         fail_file();
 158                 }
 159                 if (file_ptr < file_end) {
 160                         cnt = file_end - file_ptr;
 161                 } else {
 162                         cnt = 0;
 163                         idx = aoffset - count;
 164                 }
 165         }
 166
 167         if (cnt)
 168                 memcpy(file_ptr, buf, cnt);
 169
 170         if (cnt < count)
 171                 memcpy(file_append + idx, buf + cnt, count - cnt);
 172
 173         file_ptr += count;
 174         return count;
 175 }
 176
 177 static void *
 178 umalloc(size_t size)
 179 {
 180         void *const addr = malloc(size);
 181         if (addr == 0) {
 182                 fprintf(stderr, "malloc failed: %zu bytes\n", size);
 183                 fail_file();
 184         }
 185         return addr;
 186 }
 187
 188 static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
 189 static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
 190 static unsigned char *ideal_nop;
 191
 192 static char rel_type_nop;
 193
 194 static int (*make_nop)(void *map, size_t const offset);
 195
 196 static int make_nop_x86(void *map, size_t const offset)
 197 {
 198         uint32_t *ptr;
 199         unsigned char *op;
 200
 201         /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
 202         ptr = map + offset;
 203         if (*ptr != 0)
 204                 return -1;
 205
 206         op = map + offset - 1;
 207         if (*op != 0xe8)
 208                 return -1;
 209
 210         /* convert to nop */
 211         ulseek(fd_map, offset - 1, SEEK_SET);
 212         uwrite(fd_map, ideal_nop, 5);
 213         return 0;
 214 }
 215
 216 static unsigned char ideal_nop4_arm_le[4] = { 0x00, 0x00, 0xa0, 0xe1 }; /* mov r0, r0 */
 217 static unsigned char ideal_nop4_arm_be[4] = { 0xe1, 0xa0, 0x00, 0x00 }; /* mov r0, r0 */
 218 static unsigned char *ideal_nop4_arm;
 219
 220 static unsigned char bl_mcount_arm_le[4] = { 0xfe, 0xff, 0xff, 0xeb }; /* bl */
 221 static unsigned char bl_mcount_arm_be[4] = { 0xeb, 0xff, 0xff, 0xfe }; /* bl */
 222 static unsigned char *bl_mcount_arm;
 223
 224 static unsigned char push_arm_le[4] = { 0x04, 0xe0, 0x2d, 0xe5 }; /* push {lr} */
 225 static unsigned char push_arm_be[4] = { 0xe5, 0x2d, 0xe0, 0x04 }; /* push {lr} */
 226 static unsigned char *push_arm;
 227
 228 static unsigned char ideal_nop2_thumb_le[2] = { 0x00, 0xbf }; /* nop */
 229 static unsigned char ideal_nop2_thumb_be[2] = { 0xbf, 0x00 }; /* nop */
 230 static unsigned char *ideal_nop2_thumb;
 231
 232 static unsigned char push_bl_mcount_thumb_le[6] = { 0x00, 0xb5, 0xff, 0xf7, 0xfe, 0xff }; /* push {lr}, bl */
 233 static unsigned char push_bl_mcount_thumb_be[6] = { 0xb5, 0x00, 0xf7, 0xff, 0xff, 0xfe }; /* push {lr}, bl */
 234 static unsigned char *push_bl_mcount_thumb;
 235
 236 static int make_nop_arm(void *map, size_t const offset)
 237 {
 238         char *ptr;
 239         int cnt = 1;
 240         int nop_size;
 241         size_t off = offset;
 242
 243         ptr = map + offset;
 244         if (memcmp(ptr, bl_mcount_arm, 4) == 0) {
 245                 if (memcmp(ptr - 4, push_arm, 4) == 0) {
 246                         off -= 4;
 247                         cnt = 2;
 248                 }
 249                 ideal_nop = ideal_nop4_arm;
 250                 nop_size = 4;
 251         } else if (memcmp(ptr - 2, push_bl_mcount_thumb, 6) == 0) {
 252                 cnt = 3;
 253                 nop_size = 2;
 254                 off -= 2;
 255                 ideal_nop = ideal_nop2_thumb;
 256         } else
 257                 return -1;
 258
 259         /* Convert to nop */
 260         ulseek(fd_map, off, SEEK_SET);
 261
 262         do {
 263                 uwrite(fd_map, ideal_nop, nop_size);
 264         } while (--cnt > 0);
 265
 266         return 0;
 267 }
 268
 269 static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5};
 270 static int make_nop_arm64(void *map, size_t const offset)
 271 {
 272         uint32_t *ptr;
 273
 274         ptr = map + offset;
 275         /* bl <_mcount> is 0x94000000 before relocation */
 276         if (*ptr != 0x94000000)
 277                 return -1;
 278
 279         /* Convert to nop */
 280         ulseek(fd_map, offset, SEEK_SET);
 281         uwrite(fd_map, ideal_nop, 4);
 282         return 0;
 283 }
 284
 285 /*
 286  * Get the whole file as a programming convenience in order to avoid
 287  * malloc+lseek+read+free of many pieces.  If successful, then mmap
 288  * avoids copying unused pieces; else just read the whole file.
 289  * Open for both read and write; new info will be appended to the file.
 290  * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
 291  * do not propagate to the file until an explicit overwrite at the last.
 292  * This preserves most aspects of consistency (all except .st_size)
 293  * for simultaneous readers of the file while we are appending to it.
 294  * However, multiple writers still are bad.  We choose not to use
 295  * locking because it is expensive and the use case of kernel build
 296  * makes multiple writers unlikely.
 297  */
 298 static void *mmap_file(char const *fname)
 299 {
 300         fd_map = open(fname, O_RDONLY);
 301         if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
 302                 perror(fname);
 303                 fail_file();
 304         }
 305         if (!S_ISREG(sb.st_mode)) {
 306                 fprintf(stderr, "not a regular file: %s\n", fname);
 307                 fail_file();
 308         }
 309         file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
 310                         fd_map, 0);
 311         mmap_failed = 0;
 312         if (file_map == MAP_FAILED) {
 313                 mmap_failed = 1;
 314                 file_map = umalloc(sb.st_size);
 315                 uread(fd_map, file_map, sb.st_size);
 316         }
 317         close(fd_map);
 318
 319         file_end = file_map + sb.st_size;
 320
 321         return file_map;
 322 }
 323
 324 static void write_file(const char *fname)
 325 {
 326         char tmp_file[strlen(fname) + 4];
 327         size_t n;
 328
 329         if (!file_updated)
 330                 return;
 331
 332         sprintf(tmp_file, "%s.rc", fname);
 333
 334         /*
 335          * After reading the entire file into memory, delete it
 336          * and write it back, to prevent weird side effects of modifying
 337          * an object file in place.
 338          */
 339         fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
 340         if (fd_map < 0) {
 341                 perror(fname);
 342                 fail_file();
 343         }
 344         n = write(fd_map, file_map, sb.st_size);
 345         if (n != sb.st_size) {
 346                 perror("write");
 347                 fail_file();
 348         }
 349         if (file_append_size) {
 350                 n = write(fd_map, file_append, file_append_size);
 351                 if (n != file_append_size) {
 352                         perror("write");
 353                         fail_file();
 354                 }
 355         }
 356         close(fd_map);
 357         if (rename(tmp_file, fname) < 0) {
 358                 perror(fname);
 359                 fail_file();
 360         }
 361 }
 362
 363 /* w8rev, w8nat, ...: Handle endianness. */
 364
 365 static uint64_t w8rev(uint64_t const x)
 366 {
 367         return   ((0xff & (x >> (0 * 8))) << (7 * 8))
 368                | ((0xff & (x >> (1 * 8))) << (6 * 8))
 369                | ((0xff & (x >> (2 * 8))) << (5 * 8))
 370                | ((0xff & (x >> (3 * 8))) << (4 * 8))
 371                | ((0xff & (x >> (4 * 8))) << (3 * 8))
 372                | ((0xff & (x >> (5 * 8))) << (2 * 8))
 373                | ((0xff & (x >> (6 * 8))) << (1 * 8))
 374                | ((0xff & (x >> (7 * 8))) << (0 * 8));
 375 }
 376
 377 static uint32_t w4rev(uint32_t const x)
 378 {
 379         return   ((0xff & (x >> (0 * 8))) << (3 * 8))
 380                | ((0xff & (x >> (1 * 8))) << (2 * 8))
 381                | ((0xff & (x >> (2 * 8))) << (1 * 8))
 382                | ((0xff & (x >> (3 * 8))) << (0 * 8));
 383 }
 384
 385 static uint32_t w2rev(uint16_t const x)
 386 {
 387         return   ((0xff & (x >> (0 * 8))) << (1 * 8))
 388                | ((0xff & (x >> (1 * 8))) << (0 * 8));
 389 }
 390
 391 static uint64_t w8nat(uint64_t const x)
 392 {
 393         return x;
 394 }
 395
 396 static uint32_t w4nat(uint32_t const x)
 397 {
 398         return x;
 399 }
 400
 401 static uint32_t w2nat(uint16_t const x)
 402 {
 403         return x;
 404 }
 405
 406 static uint64_t (*w8)(uint64_t);
 407 static uint32_t (*w)(uint32_t);
 408 static uint32_t (*w2)(uint16_t);
 409
 410 /* Names of the sections that could contain calls to mcount. */
 411 static int
 412 is_mcounted_section_name(char const *const txtname)
 413 {
 414         return strcmp(".text",           txtname) == 0 ||
 415                 strcmp(".ref.text",      txtname) == 0 ||
 416                 strcmp(".sched.text",    txtname) == 0 ||
 417                 strcmp(".spinlock.text", txtname) == 0 ||
 418                 strcmp(".irqentry.text", txtname) == 0 ||
 419                 strcmp(".softirqentry.text", txtname) == 0 ||
 420                 strcmp(".kprobes.text", txtname) == 0 ||
 421                 strcmp(".cpuidle.text", txtname) == 0 ||
 422                 strcmp(".text.unlikely", txtname) == 0;
 423 }
 424
 425 /* 32 bit and 64 bit are very similar */
 426 #include "recordmcount.h"
 427 #define RECORD_MCOUNT_64
 428 #include "recordmcount.h"
 429
 430 /* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
 431  * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
 432  * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
 433  * to imply the order of the members; the spec does not say so.
 434  *      typedef unsigned char Elf64_Byte;
 435  * fails on MIPS64 because their <elf.h> already has it!
 436  */
 437
 438 typedef uint8_t myElf64_Byte;           /* Type for a 8-bit quantity.  */
 439
 440 union mips_r_info {
 441         Elf64_Xword r_info;
 442         struct {
 443                 Elf64_Word r_sym;               /* Symbol index.  */
 444                 myElf64_Byte r_ssym;            /* Special symbol.  */
 445                 myElf64_Byte r_type3;           /* Third relocation.  */
 446                 myElf64_Byte r_type2;           /* Second relocation.  */
 447                 myElf64_Byte r_type;            /* First relocation.  */
 448         } r_mips;
 449 };
 450
 451 static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
 452 {
 453         return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
 454 }
 455
 456 static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
 457 {
 458         rp->r_info = ((union mips_r_info){
 459                 .r_mips = { .r_sym = w(sym), .r_type = type }
 460         }).r_info;
 461 }
 462
 463 static void
 464 do_file(char const *const fname)
 465 {
 466         Elf32_Ehdr *const ehdr = mmap_file(fname);
 467         unsigned int reltype = 0;
 468
 469         w = w4nat;
 470         w2 = w2nat;
 471         w8 = w8nat;
 472         switch (ehdr->e_ident[EI_DATA]) {
 473                 static unsigned int const endian = 1;
 474         default:
 475                 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 476                         ehdr->e_ident[EI_DATA], fname);
 477                 fail_file();
 478                 break;
 479         case ELFDATA2LSB:
 480                 if (*(unsigned char const *)&endian != 1) {
 481                         /* main() is big endian, file.o is little endian. */
 482                         w = w4rev;
 483                         w2 = w2rev;
 484                         w8 = w8rev;
 485                 }
 486                 ideal_nop4_arm = ideal_nop4_arm_le;
 487                 bl_mcount_arm = bl_mcount_arm_le;
 488                 push_arm = push_arm_le;
 489                 ideal_nop2_thumb = ideal_nop2_thumb_le;
 490                 push_bl_mcount_thumb = push_bl_mcount_thumb_le;
 491                 break;
 492         case ELFDATA2MSB:
 493                 if (*(unsigned char const *)&endian != 0) {
 494                         /* main() is little endian, file.o is big endian. */
 495                         w = w4rev;
 496                         w2 = w2rev;
 497                         w8 = w8rev;
 498                 }
 499                 ideal_nop4_arm = ideal_nop4_arm_be;
 500                 bl_mcount_arm = bl_mcount_arm_be;
 501                 push_arm = push_arm_be;
 502                 ideal_nop2_thumb = ideal_nop2_thumb_be;
 503                 push_bl_mcount_thumb = push_bl_mcount_thumb_be;
 504                 break;
 505         }  /* end switch */
 506         if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
 507         ||  w2(ehdr->e_type) != ET_REL
 508         ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 509                 fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
 510                 fail_file();
 511         }
 512
 513         gpfx = 0;
 514         switch (w2(ehdr->e_machine)) {
 515         default:
 516                 fprintf(stderr, "unrecognized e_machine %d %s\n",
 517                         w2(ehdr->e_machine), fname);
 518                 fail_file();
 519                 break;
 520         case EM_386:
 521                 reltype = R_386_32;
 522                 rel_type_nop = R_386_NONE;
 523                 make_nop = make_nop_x86;
 524                 ideal_nop = ideal_nop5_x86_32;
 525                 mcount_adjust_32 = -1;
 526                 break;
 527         case EM_ARM:     reltype = R_ARM_ABS32;
 528                          altmcount = "__gnu_mcount_nc";
 529                          make_nop = make_nop_arm;
 530                          rel_type_nop = R_ARM_NONE;
 531                          break;
 532         case EM_AARCH64:
 533                         reltype = R_AARCH64_ABS64;
 534                         make_nop = make_nop_arm64;
 535                         rel_type_nop = R_AARCH64_NONE;
 536                         ideal_nop = ideal_nop4_arm64;
 537                         gpfx = '_';
 538                         break;
 539         case EM_IA_64:   reltype = R_IA64_IMM64;   gpfx = '_'; break;
 540         case EM_METAG:   reltype = R_METAG_ADDR32;
 541                          altmcount = "_mcount_wrapper";
 542                          rel_type_nop = R_METAG_NONE;
 543                          /* We happen to have the same requirement as MIPS */
 544                          is_fake_mcount32 = MIPS32_is_fake_mcount;
 545                          break;
 546         case EM_MIPS:    /* reltype: e_class    */ gpfx = '_'; break;
 547         case EM_PPC:     reltype = R_PPC_ADDR32;   gpfx = '_'; break;
 548         case EM_PPC64:   reltype = R_PPC64_ADDR64; gpfx = '_'; break;
 549         case EM_S390:    /* reltype: e_class    */ gpfx = '_'; break;
 550         case EM_SH:      reltype = R_SH_DIR32;                 break;
 551         case EM_SPARCV9: reltype = R_SPARC_64;     gpfx = '_'; break;
 552         case EM_X86_64:
 553                 make_nop = make_nop_x86;
 554                 ideal_nop = ideal_nop5_x86_64;
 555                 reltype = R_X86_64_64;
 556                 rel_type_nop = R_X86_64_NONE;
 557                 mcount_adjust_64 = -1;
 558                 break;
 559         }  /* end switch */
 560
 561         switch (ehdr->e_ident[EI_CLASS]) {
 562         default:
 563                 fprintf(stderr, "unrecognized ELF class %d %s\n",
 564                         ehdr->e_ident[EI_CLASS], fname);
 565                 fail_file();
 566                 break;
 567         case ELFCLASS32:
 568                 if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 569                 ||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 570                         fprintf(stderr,
 571                                 "unrecognized ET_REL file: %s\n", fname);
 572                         fail_file();
 573                 }
 574                 if (w2(ehdr->e_machine) == EM_MIPS) {
 575                         reltype = R_MIPS_32;
 576                         is_fake_mcount32 = MIPS32_is_fake_mcount;
 577                 }
 578                 do32(ehdr, fname, reltype);
 579                 break;
 580         case ELFCLASS64: {
 581                 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
 582                 if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
 583                 ||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 584                         fprintf(stderr,
 585                                 "unrecognized ET_REL file: %s\n", fname);
 586                         fail_file();
 587                 }
 588                 if (w2(ghdr->e_machine) == EM_S390) {
 589                         reltype = R_390_64;
 590                         mcount_adjust_64 = -14;
 591                 }
 592                 if (w2(ghdr->e_machine) == EM_MIPS) {
 593                         reltype = R_MIPS_64;
 594                         Elf64_r_sym = MIPS64_r_sym;
 595                         Elf64_r_info = MIPS64_r_info;
 596                         is_fake_mcount64 = MIPS64_is_fake_mcount;
 597                 }
 598                 do64(ghdr, fname, reltype);
 599                 break;
 600         }
 601         }  /* end switch */
 602
 603         write_file(fname);
 604         cleanup();
 605 }
 606
 607 int
 608 main(int argc, char *argv[])
 609 {
 610         const char ftrace[] = "/ftrace.o";
 611         int ftrace_size = sizeof(ftrace) - 1;
 612         int n_error = 0;  /* gcc-4.3.0 false positive complaint */
 613         int c;
 614         int i;
 615
 616         while ((c = getopt(argc, argv, "w")) >= 0) {
 617                 switch (c) {
 618                 case 'w':
 619                         warn_on_notrace_sect = 1;
 620                         break;
 621                 default:
 622                         fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
 623                         return 0;
 624                 }
 625         }
 626
 627         if ((argc - optind) < 1) {
 628                 fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
 629                 return 0;
 630         }
 631
 632         /* Process each file in turn, allowing deep failure. */
 633         for (i = optind; i < argc; i++) {
 634                 char *file = argv[i];
 635                 int const sjval = setjmp(jmpenv);
 636                 int len;
 637
 638                 /*
 639                  * The file kernel/trace/ftrace.o references the mcount
 640                  * function but does not call it. Since ftrace.o should
 641                  * not be traced anyway, we just skip it.
 642                  */
 643                 len = strlen(file);
 644                 if (len >= ftrace_size &&
 645                     strcmp(file + (len - ftrace_size), ftrace) == 0)
 646                         continue;
 647
 648                 switch (sjval) {
 649                 default:
 650                         fprintf(stderr, "internal error: %s\n", file);
 651                         exit(1);
 652                         break;
 653                 case SJ_SETJMP:    /* normal sequence */
 654                         /* Avoid problems if early cleanup() */
 655                         fd_map = -1;
 656                         mmap_failed = 1;
 657                         file_map = NULL;
 658                         file_ptr = NULL;
 659                         file_updated = 0;
 660                         do_file(file);
 661                         break;
 662                 case SJ_FAIL:    /* error in do_file or below */
 663                         fprintf(stderr, "%s: failed\n", file);
 664                         ++n_error;
 665                         break;
 666                 case SJ_SUCCEED:    /* premature success */
 667                         /* do nothing */
 668                         break;
 669                 }  /* end switch */
 670         }
 671         return !!n_error;
 672 }