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