scripts/sortextable.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * sortextable.h
   4  *
   5  * Copyright 2011 - 2012 Cavium, Inc.
   6  *
   7  * Some of this code was taken out of recordmcount.h written by:
   8  *
   9  * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
  10  * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
  11  */
  12
  13 #undef extable_ent_size
  14 #undef compare_extable
  15 #undef do_func
  16 #undef Elf_Addr
  17 #undef Elf_Ehdr
  18 #undef Elf_Shdr
  19 #undef Elf_Rel
  20 #undef Elf_Rela
  21 #undef Elf_Sym
  22 #undef ELF_R_SYM
  23 #undef Elf_r_sym
  24 #undef ELF_R_INFO
  25 #undef Elf_r_info
  26 #undef ELF_ST_BIND
  27 #undef ELF_ST_TYPE
  28 #undef fn_ELF_R_SYM
  29 #undef fn_ELF_R_INFO
  30 #undef uint_t
  31 #undef _r
  32 #undef _w
  33
  34 #ifdef SORTEXTABLE_64
  35 # define extable_ent_size       16
  36 # define compare_extable        compare_extable_64
  37 # define do_func                do64
  38 # define Elf_Addr               Elf64_Addr
  39 # define Elf_Ehdr               Elf64_Ehdr
  40 # define Elf_Shdr               Elf64_Shdr
  41 # define Elf_Rel                Elf64_Rel
  42 # define Elf_Rela               Elf64_Rela
  43 # define Elf_Sym                Elf64_Sym
  44 # define ELF_R_SYM              ELF64_R_SYM
  45 # define Elf_r_sym              Elf64_r_sym
  46 # define ELF_R_INFO             ELF64_R_INFO
  47 # define Elf_r_info             Elf64_r_info
  48 # define ELF_ST_BIND            ELF64_ST_BIND
  49 # define ELF_ST_TYPE            ELF64_ST_TYPE
  50 # define fn_ELF_R_SYM           fn_ELF64_R_SYM
  51 # define fn_ELF_R_INFO          fn_ELF64_R_INFO
  52 # define uint_t                 uint64_t
  53 # define _r                     r8
  54 # define _w                     w8
  55 #else
  56 # define extable_ent_size       8
  57 # define compare_extable        compare_extable_32
  58 # define do_func                do32
  59 # define Elf_Addr               Elf32_Addr
  60 # define Elf_Ehdr               Elf32_Ehdr
  61 # define Elf_Shdr               Elf32_Shdr
  62 # define Elf_Rel                Elf32_Rel
  63 # define Elf_Rela               Elf32_Rela
  64 # define Elf_Sym                Elf32_Sym
  65 # define ELF_R_SYM              ELF32_R_SYM
  66 # define Elf_r_sym              Elf32_r_sym
  67 # define ELF_R_INFO             ELF32_R_INFO
  68 # define Elf_r_info             Elf32_r_info
  69 # define ELF_ST_BIND            ELF32_ST_BIND
  70 # define ELF_ST_TYPE            ELF32_ST_TYPE
  71 # define fn_ELF_R_SYM           fn_ELF32_R_SYM
  72 # define fn_ELF_R_INFO          fn_ELF32_R_INFO
  73 # define uint_t                 uint32_t
  74 # define _r                     r
  75 # define _w                     w
  76 #endif
  77
  78 static int compare_extable(const void *a, const void *b)
  79 {
  80         Elf_Addr av = _r(a);
  81         Elf_Addr bv = _r(b);
  82
  83         if (av < bv)
  84                 return -1;
  85         if (av > bv)
  86                 return 1;
  87         return 0;
  88 }
  89
  90 static void
  91 do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
  92 {
  93         Elf_Shdr *shdr;
  94         Elf_Shdr *shstrtab_sec;
  95         Elf_Shdr *strtab_sec = NULL;
  96         Elf_Shdr *symtab_sec = NULL;
  97         Elf_Shdr *extab_sec = NULL;
  98         Elf_Sym *sym;
  99         const Elf_Sym *symtab;
 100         Elf32_Word *symtab_shndx_start = NULL;
 101         Elf_Sym *sort_needed_sym;
 102         Elf_Shdr *sort_needed_sec;
 103         Elf_Rel *relocs = NULL;
 104         int relocs_size = 0;
 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         unsigned int num_sections;
 113         unsigned int secindex_strings;
 114
 115         shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
 116
 117         num_sections = r2(&ehdr->e_shnum);
 118         if (num_sections == SHN_UNDEF)
 119                 num_sections = _r(&shdr[0].sh_size);
 120
 121         secindex_strings = r2(&ehdr->e_shstrndx);
 122         if (secindex_strings == SHN_XINDEX)
 123                 secindex_strings = r(&shdr[0].sh_link);
 124
 125         shstrtab_sec = shdr + secindex_strings;
 126         secstrtab = (const char *)ehdr + _r(&shstrtab_sec->sh_offset);
 127         for (i = 0; i < num_sections; i++) {
 128                 idx = r(&shdr[i].sh_name);
 129                 if (strcmp(secstrtab + idx, "__ex_table") == 0) {
 130                         extab_sec = shdr + i;
 131                         extab_index = i;
 132                 }
 133                 if ((r(&shdr[i].sh_type) == SHT_REL ||
 134                      r(&shdr[i].sh_type) == SHT_RELA) &&
 135                     r(&shdr[i].sh_info) == extab_index) {
 136                         relocs = (void *)ehdr + _r(&shdr[i].sh_offset);
 137                         relocs_size = _r(&shdr[i].sh_size);
 138                 }
 139                 if (strcmp(secstrtab + idx, ".symtab") == 0)
 140                         symtab_sec = shdr + i;
 141                 if (strcmp(secstrtab + idx, ".strtab") == 0)
 142                         strtab_sec = shdr + i;
 143                 if (r(&shdr[i].sh_type) == SHT_SYMTAB_SHNDX)
 144                         symtab_shndx_start = (Elf32_Word *)(
 145                                 (const char *)ehdr + _r(&shdr[i].sh_offset));
 146         }
 147         if (strtab_sec == NULL) {
 148                 fprintf(stderr, "no .strtab in  file: %s\n", fname);
 149                 fail_file();
 150         }
 151         if (symtab_sec == NULL) {
 152                 fprintf(stderr, "no .symtab in  file: %s\n", fname);
 153                 fail_file();
 154         }
 155         symtab = (const Elf_Sym *)((const char *)ehdr +
 156                                    _r(&symtab_sec->sh_offset));
 157         if (extab_sec == NULL) {
 158                 fprintf(stderr, "no __ex_table in  file: %s\n", fname);
 159                 fail_file();
 160         }
 161         strtab = (const char *)ehdr + _r(&strtab_sec->sh_offset);
 162
 163         extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
 164
 165         if (custom_sort) {
 166                 custom_sort(extab_image, _r(&extab_sec->sh_size));
 167         } else {
 168                 int num_entries = _r(&extab_sec->sh_size) / extable_ent_size;
 169                 qsort(extab_image, num_entries,
 170                       extable_ent_size, compare_extable);
 171         }
 172         /* If there were relocations, we no longer need them. */
 173         if (relocs)
 174                 memset(relocs, 0, relocs_size);
 175
 176         /* find main_extable_sort_needed */
 177         sort_needed_sym = NULL;
 178         for (i = 0; i < _r(&symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
 179                 sym = (void *)ehdr + _r(&symtab_sec->sh_offset);
 180                 sym += i;
 181                 if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
 182                         continue;
 183                 idx = r(&sym->st_name);
 184                 if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
 185                         sort_needed_sym = sym;
 186                         break;
 187                 }
 188         }
 189         if (sort_needed_sym == NULL) {
 190                 fprintf(stderr,
 191                         "no main_extable_sort_needed symbol in  file: %s\n",
 192                         fname);
 193                 fail_file();
 194         }
 195         sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
 196                                              sort_needed_sym - symtab,
 197                                              symtab_shndx_start)];
 198         sort_done_location = (void *)ehdr +
 199                 _r(&sort_needed_sec->sh_offset) +
 200                 _r(&sort_needed_sym->st_value) -
 201                 _r(&sort_needed_sec->sh_addr);
 202
 203 #if 0
 204         printf("sort done marker at %lx\n",
 205                (unsigned long)((char *)sort_done_location - (char *)ehdr));
 206 #endif
 207         /* We sorted it, clear the flag. */
 208         w(0, sort_done_location);
 209 }