scripts/sortextable.h

   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
  80 static 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
  92 static void
  93 do_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         const Elf_Sym *symtab;
 102         Elf32_Word *symtab_shndx_start = NULL;
 103         Elf_Sym *sort_needed_sym;
 104         Elf_Shdr *sort_needed_sec;
 105         Elf_Rel *relocs = NULL;
 106         int relocs_size = 0;
 107         uint32_t *sort_done_location;
 108         const char *secstrtab;
 109         const char *strtab;
 110         char *extab_image;
 111         int extab_index = 0;
 112         int i;
 113         int idx;
 114         unsigned int num_sections;
 115         unsigned int secindex_strings;
 116
 117         shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
 118
 119         num_sections = r2(&ehdr->e_shnum);
 120         if (num_sections == SHN_UNDEF)
 121                 num_sections = _r(&shdr[0].sh_size);
 122
 123         secindex_strings = r2(&ehdr->e_shstrndx);
 124         if (secindex_strings == SHN_XINDEX)
 125                 secindex_strings = r(&shdr[0].sh_link);
 126
 127         shstrtab_sec = shdr + secindex_strings;
 128         secstrtab = (const char *)ehdr + _r(&shstrtab_sec->sh_offset);
 129         for (i = 0; i < num_sections; i++) {
 130                 idx = r(&shdr[i].sh_name);
 131                 if (strcmp(secstrtab + idx, "__ex_table") == 0) {
 132                         extab_sec = shdr + i;
 133                         extab_index = i;
 134                 }
 135                 if ((r(&shdr[i].sh_type) == SHT_REL ||
 136                      r(&shdr[i].sh_type) == SHT_RELA) &&
 137                     r(&shdr[i].sh_info) == extab_index) {
 138                         relocs = (void *)ehdr + _r(&shdr[i].sh_offset);
 139                         relocs_size = _r(&shdr[i].sh_size);
 140                 }
 141                 if (strcmp(secstrtab + idx, ".symtab") == 0)
 142                         symtab_sec = shdr + i;
 143                 if (strcmp(secstrtab + idx, ".strtab") == 0)
 144                         strtab_sec = shdr + i;
 145                 if (r(&shdr[i].sh_type) == SHT_SYMTAB_SHNDX)
 146                         symtab_shndx_start = (Elf32_Word *)(
 147                                 (const char *)ehdr + _r(&shdr[i].sh_offset));
 148         }
 149         if (strtab_sec == NULL) {
 150                 fprintf(stderr, "no .strtab in  file: %s\n", fname);
 151                 fail_file();
 152         }
 153         if (symtab_sec == NULL) {
 154                 fprintf(stderr, "no .symtab in  file: %s\n", fname);
 155                 fail_file();
 156         }
 157         symtab = (const Elf_Sym *)((const char *)ehdr +
 158                                    _r(&symtab_sec->sh_offset));
 159         if (extab_sec == NULL) {
 160                 fprintf(stderr, "no __ex_table in  file: %s\n", fname);
 161                 fail_file();
 162         }
 163         strtab = (const char *)ehdr + _r(&strtab_sec->sh_offset);
 164
 165         extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
 166
 167         if (custom_sort) {
 168                 custom_sort(extab_image, _r(&extab_sec->sh_size));
 169         } else {
 170                 int num_entries = _r(&extab_sec->sh_size) / extable_ent_size;
 171                 qsort(extab_image, num_entries,
 172                       extable_ent_size, compare_extable);
 173         }
 174         /* If there were relocations, we no longer need them. */
 175         if (relocs)
 176                 memset(relocs, 0, relocs_size);
 177
 178         /* find main_extable_sort_needed */
 179         sort_needed_sym = NULL;
 180         for (i = 0; i < _r(&symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
 181                 sym = (void *)ehdr + _r(&symtab_sec->sh_offset);
 182                 sym += i;
 183                 if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
 184                         continue;
 185                 idx = r(&sym->st_name);
 186                 if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
 187                         sort_needed_sym = sym;
 188                         break;
 189                 }
 190         }
 191         if (sort_needed_sym == NULL) {
 192                 fprintf(stderr,
 193                         "no main_extable_sort_needed symbol in  file: %s\n",
 194                         fname);
 195                 fail_file();
 196         }
 197         sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
 198                                              sort_needed_sym - symtab,
 199                                              symtab_shndx_start)];
 200         sort_done_location = (void *)ehdr +
 201                 _r(&sort_needed_sec->sh_offset) +
 202                 _r(&sort_needed_sym->st_value) -
 203                 _r(&sort_needed_sec->sh_addr);
 204
 205 #if 0
 206         printf("sort done marker at %lx\n",
 207                (unsigned long)((char *)sort_done_location - (char *)ehdr));
 208 #endif
 209         /* We sorted it, clear the flag. */
 210         w(0, sort_done_location);
 211 }