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