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