scripts/sortextable.c

   1 /*
   2  * sortextable.c: Sort the kernel's exception table
   3  *
   4  * Copyright 2011 - 2012 Cavium, Inc.
   5  *
   6  * Based on code taken from recortmcount.c which is:
   7  *
   8  * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
   9  * Licensed under the GNU General Public License, version 2 (GPLv2).
  10  *
  11  * Restructured to fit Linux format, as well as other updates:
  12  *  Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
  13  */
  14
  15 /*
  16  * Strategy: alter the vmlinux file in-place.
  17  */
  18
  19 #include <sys/types.h>
  20 #include <sys/mman.h>
  21 #include <sys/stat.h>
  22 #include <getopt.h>
  23 #include <elf.h>
  24 #include <fcntl.h>
  25 #include <setjmp.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <tools/be_byteshift.h>
  32 #include <tools/le_byteshift.h>
  33
  34 #ifndef EM_AARCH64
  35 #define EM_AARCH64      183
  36 #endif
  37
  38 static int fd_map;      /* File descriptor for file being modified. */
  39 static int mmap_failed; /* Boolean flag. */
  40 static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
  41 static struct stat sb;  /* Remember .st_size, etc. */
  42 static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */
  43
  44 /* setjmp() return values */
  45 enum {
  46         SJ_SETJMP = 0,  /* hardwired first return */
  47         SJ_FAIL,
  48         SJ_SUCCEED
  49 };
  50
  51 /* Per-file resource cleanup when multiple files. */
  52 static void
  53 cleanup(void)
  54 {
  55         if (!mmap_failed)
  56                 munmap(ehdr_curr, sb.st_size);
  57         close(fd_map);
  58 }
  59
  60 static void __attribute__((noreturn))
  61 fail_file(void)
  62 {
  63         cleanup();
  64         longjmp(jmpenv, SJ_FAIL);
  65 }
  66
  67 static void __attribute__((noreturn))
  68 succeed_file(void)
  69 {
  70         cleanup();
  71         longjmp(jmpenv, SJ_SUCCEED);
  72 }
  73
  74
  75 /*
  76  * Get the whole file as a programming convenience in order to avoid
  77  * malloc+lseek+read+free of many pieces.  If successful, then mmap
  78  * avoids copying unused pieces; else just read the whole file.
  79  * Open for both read and write.
  80  */
  81 static void *mmap_file(char const *fname)
  82 {
  83         void *addr;
  84
  85         fd_map = open(fname, O_RDWR);
  86         if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
  87                 perror(fname);
  88                 fail_file();
  89         }
  90         if (!S_ISREG(sb.st_mode)) {
  91                 fprintf(stderr, "not a regular file: %s\n", fname);
  92                 fail_file();
  93         }
  94         addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
  95                     fd_map, 0);
  96         if (addr == MAP_FAILED) {
  97                 mmap_failed = 1;
  98                 fprintf(stderr, "Could not mmap file: %s\n", fname);
  99                 fail_file();
 100         }
 101         return addr;
 102 }
 103
 104 static uint64_t r8be(const uint64_t *x)
 105 {
 106         return get_unaligned_be64(x);
 107 }
 108 static uint32_t rbe(const uint32_t *x)
 109 {
 110         return get_unaligned_be32(x);
 111 }
 112 static uint16_t r2be(const uint16_t *x)
 113 {
 114         return get_unaligned_be16(x);
 115 }
 116 static uint64_t r8le(const uint64_t *x)
 117 {
 118         return get_unaligned_le64(x);
 119 }
 120 static uint32_t rle(const uint32_t *x)
 121 {
 122         return get_unaligned_le32(x);
 123 }
 124 static uint16_t r2le(const uint16_t *x)
 125 {
 126         return get_unaligned_le16(x);
 127 }
 128
 129 static void w8be(uint64_t val, uint64_t *x)
 130 {
 131         put_unaligned_be64(val, x);
 132 }
 133 static void wbe(uint32_t val, uint32_t *x)
 134 {
 135         put_unaligned_be32(val, x);
 136 }
 137 static void w2be(uint16_t val, uint16_t *x)
 138 {
 139         put_unaligned_be16(val, x);
 140 }
 141 static void w8le(uint64_t val, uint64_t *x)
 142 {
 143         put_unaligned_le64(val, x);
 144 }
 145 static void wle(uint32_t val, uint32_t *x)
 146 {
 147         put_unaligned_le32(val, x);
 148 }
 149 static void w2le(uint16_t val, uint16_t *x)
 150 {
 151         put_unaligned_le16(val, x);
 152 }
 153
 154 static uint64_t (*r8)(const uint64_t *);
 155 static uint32_t (*r)(const uint32_t *);
 156 static uint16_t (*r2)(const uint16_t *);
 157 static void (*w8)(uint64_t, uint64_t *);
 158 static void (*w)(uint32_t, uint32_t *);
 159 static void (*w2)(uint16_t, uint16_t *);
 160
 161 typedef void (*table_sort_t)(char *, int);
 162
 163 /* 32 bit and 64 bit are very similar */
 164 #include "sortextable.h"
 165 #define SORTEXTABLE_64
 166 #include "sortextable.h"
 167
 168 static int compare_relative_table(const void *a, const void *b)
 169 {
 170         int32_t av = (int32_t)r(a);
 171         int32_t bv = (int32_t)r(b);
 172
 173         if (av < bv)
 174                 return -1;
 175         if (av > bv)
 176                 return 1;
 177         return 0;
 178 }
 179
 180 static void sort_relative_table(char *extab_image, int image_size)
 181 {
 182         int i;
 183
 184         /*
 185          * Do the same thing the runtime sort does, first normalize to
 186          * being relative to the start of the section.
 187          */
 188         i = 0;
 189         while (i < image_size) {
 190                 uint32_t *loc = (uint32_t *)(extab_image + i);
 191                 w(r(loc) + i, loc);
 192                 i += 4;
 193         }
 194
 195         qsort(extab_image, image_size / 8, 8, compare_relative_table);
 196
 197         /* Now denormalize. */
 198         i = 0;
 199         while (i < image_size) {
 200                 uint32_t *loc = (uint32_t *)(extab_image + i);
 201                 w(r(loc) - i, loc);
 202                 i += 4;
 203         }
 204 }
 205
 206 static void
 207 do_file(char const *const fname)
 208 {
 209         table_sort_t custom_sort;
 210         Elf32_Ehdr *ehdr = mmap_file(fname);
 211
 212         ehdr_curr = ehdr;
 213         switch (ehdr->e_ident[EI_DATA]) {
 214         default:
 215                 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 216                         ehdr->e_ident[EI_DATA], fname);
 217                 fail_file();
 218                 break;
 219         case ELFDATA2LSB:
 220                 r = rle;
 221                 r2 = r2le;
 222                 r8 = r8le;
 223                 w = wle;
 224                 w2 = w2le;
 225                 w8 = w8le;
 226                 break;
 227         case ELFDATA2MSB:
 228                 r = rbe;
 229                 r2 = r2be;
 230                 r8 = r8be;
 231                 w = wbe;
 232                 w2 = w2be;
 233                 w8 = w8be;
 234                 break;
 235         }  /* end switch */
 236         if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
 237         ||  r2(&ehdr->e_type) != ET_EXEC
 238         ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 239                 fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
 240                 fail_file();
 241         }
 242
 243         custom_sort = NULL;
 244         switch (r2(&ehdr->e_machine)) {
 245         default:
 246                 fprintf(stderr, "unrecognized e_machine %d %s\n",
 247                         r2(&ehdr->e_machine), fname);
 248                 fail_file();
 249                 break;
 250         case EM_386:
 251         case EM_X86_64:
 252         case EM_S390:
 253                 custom_sort = sort_relative_table;
 254                 break;
 255         case EM_ARM:
 256         case EM_AARCH64:
 257         case EM_MIPS:
 258                 break;
 259         }  /* end switch */
 260
 261         switch (ehdr->e_ident[EI_CLASS]) {
 262         default:
 263                 fprintf(stderr, "unrecognized ELF class %d %s\n",
 264                         ehdr->e_ident[EI_CLASS], fname);
 265                 fail_file();
 266                 break;
 267         case ELFCLASS32:
 268                 if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 269                 ||  r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 270                         fprintf(stderr,
 271                                 "unrecognized ET_EXEC file: %s\n", fname);
 272                         fail_file();
 273                 }
 274                 do32(ehdr, fname, custom_sort);
 275                 break;
 276         case ELFCLASS64: {
 277                 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
 278                 if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
 279                 ||  r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 280                         fprintf(stderr,
 281                                 "unrecognized ET_EXEC file: %s\n", fname);
 282                         fail_file();
 283                 }
 284                 do64(ghdr, fname, custom_sort);
 285                 break;
 286         }
 287         }  /* end switch */
 288
 289         cleanup();
 290 }
 291
 292 int
 293 main(int argc, char *argv[])
 294 {
 295         int n_error = 0;  /* gcc-4.3.0 false positive complaint */
 296         int i;
 297
 298         if (argc < 2) {
 299                 fprintf(stderr, "usage: sortextable vmlinux...\n");
 300                 return 0;
 301         }
 302
 303         /* Process each file in turn, allowing deep failure. */
 304         for (i = 1; i < argc; i++) {
 305                 char *file = argv[i];
 306                 int const sjval = setjmp(jmpenv);
 307
 308                 switch (sjval) {
 309                 default:
 310                         fprintf(stderr, "internal error: %s\n", file);
 311                         exit(1);
 312                         break;
 313                 case SJ_SETJMP:    /* normal sequence */
 314                         /* Avoid problems if early cleanup() */
 315                         fd_map = -1;
 316                         ehdr_curr = NULL;
 317                         mmap_failed = 1;
 318                         do_file(file);
 319                         break;
 320                 case SJ_FAIL:    /* error in do_file or below */
 321                         ++n_error;
 322                         break;
 323                 case SJ_SUCCEED:    /* premature success */
 324                         /* do nothing */
 325                         break;
 326                 }  /* end switch */
 327         }
 328         return !!n_error;
 329 }