linux/scripts/sortextable.h
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   1/*
   2 * sortextable.h
   3 *
   4 * Copyright 2011 - 2012 Cavium, Inc.
   5 *
   6 * Some of this code was taken out of recordmcount.h written by:
   7 *
   8 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
   9 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
  10 *
  11 *
  12 * Licensed under the GNU General Public License, version 2 (GPLv2).
  13 */
  14
  15#undef extable_ent_size
  16#undef compare_extable
  17#undef do_func
  18#undef Elf_Addr
  19#undef Elf_Ehdr
  20#undef Elf_Shdr
  21#undef Elf_Rel
  22#undef Elf_Rela
  23#undef Elf_Sym
  24#undef ELF_R_SYM
  25#undef Elf_r_sym
  26#undef ELF_R_INFO
  27#undef Elf_r_info
  28#undef ELF_ST_BIND
  29#undef ELF_ST_TYPE
  30#undef fn_ELF_R_SYM
  31#undef fn_ELF_R_INFO
  32#undef uint_t
  33#undef _r
  34#undef _w
  35
  36#ifdef SORTEXTABLE_64
  37# define extable_ent_size       16
  38# define compare_extable        compare_extable_64
  39# define do_func                do64
  40# define Elf_Addr               Elf64_Addr
  41# define Elf_Ehdr               Elf64_Ehdr
  42# define Elf_Shdr               Elf64_Shdr
  43# define Elf_Rel                Elf64_Rel
  44# define Elf_Rela               Elf64_Rela
  45# define Elf_Sym                Elf64_Sym
  46# define ELF_R_SYM              ELF64_R_SYM
  47# define Elf_r_sym              Elf64_r_sym
  48# define ELF_R_INFO             ELF64_R_INFO
  49# define Elf_r_info             Elf64_r_info
  50# define ELF_ST_BIND            ELF64_ST_BIND
  51# define ELF_ST_TYPE            ELF64_ST_TYPE
  52# define fn_ELF_R_SYM           fn_ELF64_R_SYM
  53# define fn_ELF_R_INFO          fn_ELF64_R_INFO
  54# define uint_t                 uint64_t
  55# define _r                     r8
  56# define _w                     w8
  57#else
  58# define extable_ent_size       8
  59# define compare_extable        compare_extable_32
  60# define do_func                do32
  61# define Elf_Addr               Elf32_Addr
  62# define Elf_Ehdr               Elf32_Ehdr
  63# define Elf_Shdr               Elf32_Shdr
  64# define Elf_Rel                Elf32_Rel
  65# define Elf_Rela               Elf32_Rela
  66# define Elf_Sym                Elf32_Sym
  67# define ELF_R_SYM              ELF32_R_SYM
  68# define Elf_r_sym              Elf32_r_sym
  69# define ELF_R_INFO             ELF32_R_INFO
  70# define Elf_r_info             Elf32_r_info
  71# define ELF_ST_BIND            ELF32_ST_BIND
  72# define ELF_ST_TYPE            ELF32_ST_TYPE
  73# define fn_ELF_R_SYM           fn_ELF32_R_SYM
  74# define fn_ELF_R_INFO          fn_ELF32_R_INFO
  75# define uint_t                 uint32_t
  76# define _r                     r
  77# define _w                     w
  78#endif
  79
  80static int compare_extable(const void *a, const void *b)
  81{
  82        Elf_Addr av = _r(a);
  83        Elf_Addr bv = _r(b);
  84
  85        if (av < bv)
  86                return -1;
  87        if (av > bv)
  88                return 1;
  89        return 0;
  90}
  91
  92static void
  93do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
  94{
  95        Elf_Shdr *shdr;
  96        Elf_Shdr *shstrtab_sec;
  97        Elf_Shdr *strtab_sec = NULL;
  98        Elf_Shdr *symtab_sec = NULL;
  99        Elf_Shdr *extab_sec = NULL;
 100        Elf_Sym *sym;
 101        Elf_Sym *sort_needed_sym;
 102        Elf_Shdr *sort_needed_sec;
 103        Elf_Rel *relocs = NULL;
 104        int relocs_size;
 105        uint32_t *sort_done_location;
 106        const char *secstrtab;
 107        const char *strtab;
 108        char *extab_image;
 109        int extab_index = 0;
 110        int i;
 111        int idx;
 112
 113        shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
 114        shstrtab_sec = shdr + r2(&ehdr->e_shstrndx);
 115        secstrtab = (const char *)ehdr + _r(&shstrtab_sec->sh_offset);
 116        for (i = 0; i < r2(&ehdr->e_shnum); i++) {
 117                idx = r(&shdr[i].sh_name);
 118                if (strcmp(secstrtab + idx, "__ex_table") == 0) {
 119                        extab_sec = shdr + i;
 120                        extab_index = i;
 121                }
 122                if ((r(&shdr[i].sh_type) == SHT_REL ||
 123                     r(&shdr[i].sh_type) == SHT_RELA) &&
 124                    r(&shdr[i].sh_info) == extab_index) {
 125                        relocs = (void *)ehdr + _r(&shdr[i].sh_offset);
 126                        relocs_size = _r(&shdr[i].sh_size);
 127                }
 128                if (strcmp(secstrtab + idx, ".symtab") == 0)
 129                        symtab_sec = shdr + i;
 130                if (strcmp(secstrtab + idx, ".strtab") == 0)
 131                        strtab_sec = shdr + i;
 132        }
 133        if (strtab_sec == NULL) {
 134                fprintf(stderr, "no .strtab in  file: %s\n", fname);
 135                fail_file();
 136        }
 137        if (symtab_sec == NULL) {
 138                fprintf(stderr, "no .symtab in  file: %s\n", fname);
 139                fail_file();
 140        }
 141        if (extab_sec == NULL) {
 142                fprintf(stderr, "no __ex_table in  file: %s\n", fname);
 143                fail_file();
 144        }
 145        strtab = (const char *)ehdr + _r(&strtab_sec->sh_offset);
 146
 147        extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
 148
 149        if (custom_sort) {
 150                custom_sort(extab_image, _r(&extab_sec->sh_size));
 151        } else {
 152                int num_entries = _r(&extab_sec->sh_size) / extable_ent_size;
 153                qsort(extab_image, num_entries,
 154                      extable_ent_size, compare_extable);
 155        }
 156        /* If there were relocations, we no longer need them. */
 157        if (relocs)
 158                memset(relocs, 0, relocs_size);
 159
 160        /* find main_extable_sort_needed */
 161        sort_needed_sym = NULL;
 162        for (i = 0; i < _r(&symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
 163                sym = (void *)ehdr + _r(&symtab_sec->sh_offset);
 164                sym += i;
 165                if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
 166                        continue;
 167                idx = r(&sym->st_name);
 168                if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
 169                        sort_needed_sym = sym;
 170                        break;
 171                }
 172        }
 173        if (sort_needed_sym == NULL) {
 174                fprintf(stderr,
 175                        "no main_extable_sort_needed symbol in  file: %s\n",
 176                        fname);
 177                fail_file();
 178        }
 179        sort_needed_sec = &shdr[r2(&sort_needed_sym->st_shndx)];
 180        sort_done_location = (void *)ehdr +
 181                _r(&sort_needed_sec->sh_offset) +
 182                _r(&sort_needed_sym->st_value) -
 183                _r(&sort_needed_sec->sh_addr);
 184
 185#if 0
 186        printf("sort done marker at %lx\n",
 187               (unsigned long)((char *)sort_done_location - (char *)ehdr));
 188#endif
 189        /* We sorted it, clear the flag. */
 190        w(0, sort_done_location);
 191}
 192
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