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_AARCH64
  39 #define EM_AARCH64      183
  40 #endif
  41
  42 #ifndef EM_MICROBLAZE
  43 #define EM_MICROBLAZE   189
  44 #endif
  45
  46 static int fd_map;      /* File descriptor for file being modified. */
  47 static int mmap_failed; /* Boolean flag. */
  48 static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
  49 static struct stat sb;  /* Remember .st_size, etc. */
  50 static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */
  51
  52 /* setjmp() return values */
  53 enum {
  54         SJ_SETJMP = 0,  /* hardwired first return */
  55         SJ_FAIL,
  56         SJ_SUCCEED
  57 };
  58
  59 /* Per-file resource cleanup when multiple files. */
  60 static void
  61 cleanup(void)
  62 {
  63         if (!mmap_failed)
  64                 munmap(ehdr_curr, sb.st_size);
  65         close(fd_map);
  66 }
  67
  68 static void __attribute__((noreturn))
  69 fail_file(void)
  70 {
  71         cleanup();
  72         longjmp(jmpenv, SJ_FAIL);
  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 /*
 164  * Move reserved section indices SHN_LORESERVE..SHN_HIRESERVE out of
 165  * the way to -256..-1, to avoid conflicting with real section
 166  * indices.
 167  */
 168 #define SPECIAL(i) ((i) - (SHN_HIRESERVE + 1))
 169
 170 static inline int is_shndx_special(unsigned int i)
 171 {
 172         return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
 173 }
 174
 175 /* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
 176 static inline unsigned int get_secindex(unsigned int shndx,
 177                                         unsigned int sym_offs,
 178                                         const Elf32_Word *symtab_shndx_start)
 179 {
 180         if (is_shndx_special(shndx))
 181                 return SPECIAL(shndx);
 182         if (shndx != SHN_XINDEX)
 183                 return shndx;
 184         return r(&symtab_shndx_start[sym_offs]);
 185 }
 186
 187 /* 32 bit and 64 bit are very similar */
 188 #include "sortextable.h"
 189 #define SORTEXTABLE_64
 190 #include "sortextable.h"
 191
 192 static int compare_relative_table(const void *a, const void *b)
 193 {
 194         int32_t av = (int32_t)r(a);
 195         int32_t bv = (int32_t)r(b);
 196
 197         if (av < bv)
 198                 return -1;
 199         if (av > bv)
 200                 return 1;
 201         return 0;
 202 }
 203
 204 static void sort_relative_table(char *extab_image, int image_size)
 205 {
 206         int i;
 207
 208         /*
 209          * Do the same thing the runtime sort does, first normalize to
 210          * being relative to the start of the section.
 211          */
 212         i = 0;
 213         while (i < image_size) {
 214                 uint32_t *loc = (uint32_t *)(extab_image + i);
 215                 w(r(loc) + i, loc);
 216                 i += 4;
 217         }
 218
 219         qsort(extab_image, image_size / 8, 8, compare_relative_table);
 220
 221         /* Now denormalize. */
 222         i = 0;
 223         while (i < image_size) {
 224                 uint32_t *loc = (uint32_t *)(extab_image + i);
 225                 w(r(loc) - i, loc);
 226                 i += 4;
 227         }
 228 }
 229
 230 static void
 231 do_file(char const *const fname)
 232 {
 233         table_sort_t custom_sort;
 234         Elf32_Ehdr *ehdr = mmap_file(fname);
 235
 236         ehdr_curr = ehdr;
 237         switch (ehdr->e_ident[EI_DATA]) {
 238         default:
 239                 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 240                         ehdr->e_ident[EI_DATA], fname);
 241                 fail_file();
 242                 break;
 243         case ELFDATA2LSB:
 244                 r = rle;
 245                 r2 = r2le;
 246                 r8 = r8le;
 247                 w = wle;
 248                 w2 = w2le;
 249                 w8 = w8le;
 250                 break;
 251         case ELFDATA2MSB:
 252                 r = rbe;
 253                 r2 = r2be;
 254                 r8 = r8be;
 255                 w = wbe;
 256                 w2 = w2be;
 257                 w8 = w8be;
 258                 break;
 259         }  /* end switch */
 260         if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
 261         ||  r2(&ehdr->e_type) != ET_EXEC
 262         ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 263                 fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
 264                 fail_file();
 265         }
 266
 267         custom_sort = NULL;
 268         switch (r2(&ehdr->e_machine)) {
 269         default:
 270                 fprintf(stderr, "unrecognized e_machine %d %s\n",
 271                         r2(&ehdr->e_machine), fname);
 272                 fail_file();
 273                 break;
 274         case EM_386:
 275         case EM_X86_64:
 276         case EM_S390:
 277                 custom_sort = sort_relative_table;
 278                 break;
 279         case EM_ARCOMPACT:
 280         case EM_ARM:
 281         case EM_AARCH64:
 282         case EM_MICROBLAZE:
 283         case EM_MIPS:
 284                 break;
 285         }  /* end switch */
 286
 287         switch (ehdr->e_ident[EI_CLASS]) {
 288         default:
 289                 fprintf(stderr, "unrecognized ELF class %d %s\n",
 290                         ehdr->e_ident[EI_CLASS], fname);
 291                 fail_file();
 292                 break;
 293         case ELFCLASS32:
 294                 if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 295                 ||  r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 296                         fprintf(stderr,
 297                                 "unrecognized ET_EXEC file: %s\n", fname);
 298                         fail_file();
 299                 }
 300                 do32(ehdr, fname, custom_sort);
 301                 break;
 302         case ELFCLASS64: {
 303                 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
 304                 if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
 305                 ||  r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 306                         fprintf(stderr,
 307                                 "unrecognized ET_EXEC file: %s\n", fname);
 308                         fail_file();
 309                 }
 310                 do64(ghdr, fname, custom_sort);
 311                 break;
 312         }
 313         }  /* end switch */
 314
 315         cleanup();
 316 }
 317
 318 int
 319 main(int argc, char *argv[])
 320 {
 321         int n_error = 0;  /* gcc-4.3.0 false positive complaint */
 322         int i;
 323
 324         if (argc < 2) {
 325                 fprintf(stderr, "usage: sortextable vmlinux...\n");
 326                 return 0;
 327         }
 328
 329         /* Process each file in turn, allowing deep failure. */
 330         for (i = 1; i < argc; i++) {
 331                 char *file = argv[i];
 332                 int const sjval = setjmp(jmpenv);
 333
 334                 switch (sjval) {
 335                 default:
 336                         fprintf(stderr, "internal error: %s\n", file);
 337                         exit(1);
 338                         break;
 339                 case SJ_SETJMP:    /* normal sequence */
 340                         /* Avoid problems if early cleanup() */
 341                         fd_map = -1;
 342                         ehdr_curr = NULL;
 343                         mmap_failed = 1;
 344                         do_file(file);
 345                         break;
 346                 case SJ_FAIL:    /* error in do_file or below */
 347                         ++n_error;
 348                         break;
 349                 case SJ_SUCCEED:    /* premature success */
 350                         /* do nothing */
 351                         break;
 352                 }  /* end switch */
 353         }
 354         return !!n_error;
 355 }