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
  67static void __attribute__((noreturn))
  68succeed_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 */
  81static 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
 104static uint64_t r8be(const uint64_t *x)
 105{
 106        return get_unaligned_be64(x);
 107}
 108static uint32_t rbe(const uint32_t *x)
 109{
 110        return get_unaligned_be32(x);
 111}
 112static uint16_t r2be(const uint16_t *x)
 113{
 114        return get_unaligned_be16(x);
 115}
 116static uint64_t r8le(const uint64_t *x)
 117{
 118        return get_unaligned_le64(x);
 119}
 120static uint32_t rle(const uint32_t *x)
 121{
 122        return get_unaligned_le32(x);
 123}
 124static uint16_t r2le(const uint16_t *x)
 125{
 126        return get_unaligned_le16(x);
 127}
 128
 129static void w8be(uint64_t val, uint64_t *x)
 130{
 131        put_unaligned_be64(val, x);
 132}
 133static void wbe(uint32_t val, uint32_t *x)
 134{
 135        put_unaligned_be32(val, x);
 136}
 137static void w2be(uint16_t val, uint16_t *x)
 138{
 139        put_unaligned_be16(val, x);
 140}
 141static void w8le(uint64_t val, uint64_t *x)
 142{
 143        put_unaligned_le64(val, x);
 144}
 145static void wle(uint32_t val, uint32_t *x)
 146{
 147        put_unaligned_le32(val, x);
 148}
 149static void w2le(uint16_t val, uint16_t *x)
 150{
 151        put_unaligned_le16(val, x);
 152}
 153
 154static uint64_t (*r8)(const uint64_t *);
 155static uint32_t (*r)(const uint32_t *);
 156static uint16_t (*r2)(const uint16_t *);
 157static void (*w8)(uint64_t, uint64_t *);
 158static void (*w)(uint32_t, uint32_t *);
 159static void (*w2)(uint16_t, uint16_t *);
 160
 161typedef 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
 168static 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
 180static 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
 206static void
 207do_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
 292int
 293main(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}
 330
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