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_ARCOMPACT
  35 #define EM_ARCOMPACT    93
  36 #endif
  37
  38 #ifndef EM_XTENSA
  39 #define EM_XTENSA       94
  40 #endif
  41
  42 #ifndef EM_AARCH64
  43 #define EM_AARCH64      183
  44 #endif
  45
  46 #ifndef EM_MICROBLAZE
  47 #define EM_MICROBLAZE   189
  48 #endif
  49
  50 static int fd_map;      /* File descriptor for file being modified. */
  51 static int mmap_failed; /* Boolean flag. */
  52 static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
  53 static struct stat sb;  /* Remember .st_size, etc. */
  54 static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */
  55
  56 /* setjmp() return values */
  57 enum {
  58         SJ_SETJMP = 0,  /* hardwired first return */
  59         SJ_FAIL,
  60         SJ_SUCCEED
  61 };
  62
  63 /* Per-file resource cleanup when multiple files. */
  64 static void
  65 cleanup(void)
  66 {
  67         if (!mmap_failed)
  68                 munmap(ehdr_curr, sb.st_size);
  69         close(fd_map);
  70 }
  71
  72 static void __attribute__((noreturn))
  73 fail_file(void)
  74 {
  75         cleanup();
  76         longjmp(jmpenv, SJ_FAIL);
  77 }
  78
  79 /*
  80  * Get the whole file as a programming convenience in order to avoid
  81  * malloc+lseek+read+free of many pieces.  If successful, then mmap
  82  * avoids copying unused pieces; else just read the whole file.
  83  * Open for both read and write.
  84  */
  85 static void *mmap_file(char const *fname)
  86 {
  87         void *addr;
  88
  89         fd_map = open(fname, O_RDWR);
  90         if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
  91                 perror(fname);
  92                 fail_file();
  93         }
  94         if (!S_ISREG(sb.st_mode)) {
  95                 fprintf(stderr, "not a regular file: %s\n", fname);
  96                 fail_file();
  97         }
  98         addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
  99                     fd_map, 0);
 100         if (addr == MAP_FAILED) {
 101                 mmap_failed = 1;
 102                 fprintf(stderr, "Could not mmap file: %s\n", fname);
 103                 fail_file();
 104         }
 105         return addr;
 106 }
 107
 108 static uint64_t r8be(const uint64_t *x)
 109 {
 110         return get_unaligned_be64(x);
 111 }
 112 static uint32_t rbe(const uint32_t *x)
 113 {
 114         return get_unaligned_be32(x);
 115 }
 116 static uint16_t r2be(const uint16_t *x)
 117 {
 118         return get_unaligned_be16(x);
 119 }
 120 static uint64_t r8le(const uint64_t *x)
 121 {
 122         return get_unaligned_le64(x);
 123 }
 124 static uint32_t rle(const uint32_t *x)
 125 {
 126         return get_unaligned_le32(x);
 127 }
 128 static uint16_t r2le(const uint16_t *x)
 129 {
 130         return get_unaligned_le16(x);
 131 }
 132
 133 static void w8be(uint64_t val, uint64_t *x)
 134 {
 135         put_unaligned_be64(val, x);
 136 }
 137 static void wbe(uint32_t val, uint32_t *x)
 138 {
 139         put_unaligned_be32(val, x);
 140 }
 141 static void w2be(uint16_t val, uint16_t *x)
 142 {
 143         put_unaligned_be16(val, x);
 144 }
 145 static void w8le(uint64_t val, uint64_t *x)
 146 {
 147         put_unaligned_le64(val, x);
 148 }
 149 static void wle(uint32_t val, uint32_t *x)
 150 {
 151         put_unaligned_le32(val, x);
 152 }
 153 static void w2le(uint16_t val, uint16_t *x)
 154 {
 155         put_unaligned_le16(val, x);
 156 }
 157
 158 static uint64_t (*r8)(const uint64_t *);
 159 static uint32_t (*r)(const uint32_t *);
 160 static uint16_t (*r2)(const uint16_t *);
 161 static void (*w8)(uint64_t, uint64_t *);
 162 static void (*w)(uint32_t, uint32_t *);
 163 static void (*w2)(uint16_t, uint16_t *);
 164
 165 typedef void (*table_sort_t)(char *, int);
 166
 167 /*
 168  * Move reserved section indices SHN_LORESERVE..SHN_HIRESERVE out of
 169  * the way to -256..-1, to avoid conflicting with real section
 170  * indices.
 171  */
 172 #define SPECIAL(i) ((i) - (SHN_HIRESERVE + 1))
 173
 174 static inline int is_shndx_special(unsigned int i)
 175 {
 176         return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
 177 }
 178
 179 /* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
 180 static inline unsigned int get_secindex(unsigned int shndx,
 181                                         unsigned int sym_offs,
 182                                         const Elf32_Word *symtab_shndx_start)
 183 {
 184         if (is_shndx_special(shndx))
 185                 return SPECIAL(shndx);
 186         if (shndx != SHN_XINDEX)
 187                 return shndx;
 188         return r(&symtab_shndx_start[sym_offs]);
 189 }
 190
 191 /* 32 bit and 64 bit are very similar */
 192 #include "sortextable.h"
 193 #define SORTEXTABLE_64
 194 #include "sortextable.h"
 195
 196 static int compare_relative_table(const void *a, const void *b)
 197 {
 198         int32_t av = (int32_t)r(a);
 199         int32_t bv = (int32_t)r(b);
 200
 201         if (av < bv)
 202                 return -1;
 203         if (av > bv)
 204                 return 1;
 205         return 0;
 206 }
 207
 208 static void sort_relative_table(char *extab_image, int image_size)
 209 {
 210         int i;
 211
 212         /*
 213          * Do the same thing the runtime sort does, first normalize to
 214          * being relative to the start of the section.
 215          */
 216         i = 0;
 217         while (i < image_size) {
 218                 uint32_t *loc = (uint32_t *)(extab_image + i);
 219                 w(r(loc) + i, loc);
 220                 i += 4;
 221         }
 222
 223         qsort(extab_image, image_size / 8, 8, compare_relative_table);
 224
 225         /* Now denormalize. */
 226         i = 0;
 227         while (i < image_size) {
 228                 uint32_t *loc = (uint32_t *)(extab_image + i);
 229                 w(r(loc) - i, loc);
 230                 i += 4;
 231         }
 232 }
 233
 234 static void
 235 do_file(char const *const fname)
 236 {
 237         table_sort_t custom_sort;
 238         Elf32_Ehdr *ehdr = mmap_file(fname);
 239
 240         ehdr_curr = ehdr;
 241         switch (ehdr->e_ident[EI_DATA]) {
 242         default:
 243                 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 244                         ehdr->e_ident[EI_DATA], fname);
 245                 fail_file();
 246                 break;
 247         case ELFDATA2LSB:
 248                 r = rle;
 249                 r2 = r2le;
 250                 r8 = r8le;
 251                 w = wle;
 252                 w2 = w2le;
 253                 w8 = w8le;
 254                 break;
 255         case ELFDATA2MSB:
 256                 r = rbe;
 257                 r2 = r2be;
 258                 r8 = r8be;
 259                 w = wbe;
 260                 w2 = w2be;
 261                 w8 = w8be;
 262                 break;
 263         }  /* end switch */
 264         if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
 265         ||  r2(&ehdr->e_type) != ET_EXEC
 266         ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 267                 fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
 268                 fail_file();
 269         }
 270
 271         custom_sort = NULL;
 272         switch (r2(&ehdr->e_machine)) {
 273         default:
 274                 fprintf(stderr, "unrecognized e_machine %d %s\n",
 275                         r2(&ehdr->e_machine), fname);
 276                 fail_file();
 277                 break;
 278         case EM_386:
 279         case EM_X86_64:
 280         case EM_S390:
 281                 custom_sort = sort_relative_table;
 282                 break;
 283         case EM_ARCOMPACT:
 284         case EM_ARM:
 285         case EM_AARCH64:
 286         case EM_MICROBLAZE:
 287         case EM_MIPS:
 288         case EM_XTENSA:
 289                 break;
 290         }  /* end switch */
 291
 292         switch (ehdr->e_ident[EI_CLASS]) {
 293         default:
 294                 fprintf(stderr, "unrecognized ELF class %d %s\n",
 295                         ehdr->e_ident[EI_CLASS], fname);
 296                 fail_file();
 297                 break;
 298         case ELFCLASS32:
 299                 if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 300                 ||  r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 301                         fprintf(stderr,
 302                                 "unrecognized ET_EXEC file: %s\n", fname);
 303                         fail_file();
 304                 }
 305                 do32(ehdr, fname, custom_sort);
 306                 break;
 307         case ELFCLASS64: {
 308                 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
 309                 if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
 310                 ||  r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 311                         fprintf(stderr,
 312                                 "unrecognized ET_EXEC file: %s\n", fname);
 313                         fail_file();
 314                 }
 315                 do64(ghdr, fname, custom_sort);
 316                 break;
 317         }
 318         }  /* end switch */
 319
 320         cleanup();
 321 }
 322
 323 int
 324 main(int argc, char *argv[])
 325 {
 326         int n_error = 0;  /* gcc-4.3.0 false positive complaint */
 327         int i;
 328
 329         if (argc < 2) {
 330                 fprintf(stderr, "usage: sortextable vmlinux...\n");
 331                 return 0;
 332         }
 333
 334         /* Process each file in turn, allowing deep failure. */
 335         for (i = 1; i < argc; i++) {
 336                 char *file = argv[i];
 337                 int const sjval = setjmp(jmpenv);
 338
 339                 switch (sjval) {
 340                 default:
 341                         fprintf(stderr, "internal error: %s\n", file);
 342                         exit(1);
 343                         break;
 344                 case SJ_SETJMP:    /* normal sequence */
 345                         /* Avoid problems if early cleanup() */
 346                         fd_map = -1;
 347                         ehdr_curr = NULL;
 348                         mmap_failed = 1;
 349                         do_file(file);
 350                         break;
 351                 case SJ_FAIL:    /* error in do_file or below */
 352                         ++n_error;
 353                         break;
 354                 case SJ_SUCCEED:    /* premature success */
 355                         /* do nothing */
 356                         break;
 357                 }  /* end switch */
 358         }
 359         return !!n_error;
 360 }