arch/mips/vdso/genvdso.h

   1 /*
   2  * Copyright (C) 2015 Imagination Technologies
   3  * Author: Alex Smith <alex.smith@imgtec.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation;  either version 2 of the  License, or (at your
   8  * option) any later version.
   9  */
  10
  11 static inline bool FUNC(patch_vdso)(const char *path, void *vdso)
  12 {
  13         const ELF(Ehdr) *ehdr = vdso;
  14         void *shdrs;
  15         ELF(Shdr) *shdr;
  16         char *shstrtab, *name;
  17         uint16_t sh_count, sh_entsize, i;
  18
  19         shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff);
  20         sh_count = swap_uint16(ehdr->e_shnum);
  21         sh_entsize = swap_uint16(ehdr->e_shentsize);
  22
  23         shdr = shdrs + (sh_entsize * swap_uint16(ehdr->e_shstrndx));
  24         shstrtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
  25
  26         for (i = 0; i < sh_count; i++) {
  27                 shdr = shdrs + (i * sh_entsize);
  28                 name = shstrtab + swap_uint32(shdr->sh_name);
  29
  30                 /*
  31                  * Ensure there are no relocation sections - ld.so does not
  32                  * relocate the VDSO so if there are relocations things will
  33                  * break.
  34                  */
  35                 switch (swap_uint32(shdr->sh_type)) {
  36                 case SHT_REL:
  37                 case SHT_RELA:
  38                         fprintf(stderr,
  39                                 "%s: '%s' contains relocation sections\n",
  40                                 program_name, path);
  41                         return false;
  42                 }
  43
  44                 /* Check for existing sections. */
  45                 if (strcmp(name, ".MIPS.abiflags") == 0) {
  46                         fprintf(stderr,
  47                                 "%s: '%s' already contains a '.MIPS.abiflags' section\n",
  48                                 program_name, path);
  49                         return false;
  50                 }
  51
  52                 if (strcmp(name, ".mips_abiflags") == 0) {
  53                         strcpy(name, ".MIPS.abiflags");
  54                         shdr->sh_type = swap_uint32(SHT_MIPS_ABIFLAGS);
  55                         shdr->sh_entsize = shdr->sh_size;
  56                 }
  57         }
  58
  59         return true;
  60 }
  61
  62 static inline bool FUNC(get_symbols)(const char *path, void *vdso)
  63 {
  64         const ELF(Ehdr) *ehdr = vdso;
  65         void *shdrs, *symtab;
  66         ELF(Shdr) *shdr;
  67         const ELF(Sym) *sym;
  68         char *strtab, *name;
  69         uint16_t sh_count, sh_entsize, st_count, st_entsize, i, j;
  70         uint64_t offset;
  71         uint32_t flags;
  72
  73         shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff);
  74         sh_count = swap_uint16(ehdr->e_shnum);
  75         sh_entsize = swap_uint16(ehdr->e_shentsize);
  76
  77         for (i = 0; i < sh_count; i++) {
  78                 shdr = shdrs + (i * sh_entsize);
  79
  80                 if (swap_uint32(shdr->sh_type) == SHT_SYMTAB)
  81                         break;
  82         }
  83
  84         if (i == sh_count) {
  85                 fprintf(stderr, "%s: '%s' has no symbol table\n", program_name,
  86                         path);
  87                 return false;
  88         }
  89
  90         /* Get flags */
  91         flags = swap_uint32(ehdr->e_flags);
  92         if (elf_class == ELFCLASS64)
  93                 elf_abi = ABI_N64;
  94         else if (flags & EF_MIPS_ABI2)
  95                 elf_abi = ABI_N32;
  96         else
  97                 elf_abi = ABI_O32;
  98
  99         /* Get symbol table. */
 100         symtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
 101         st_entsize = FUNC(swap_uint)(shdr->sh_entsize);
 102         st_count = FUNC(swap_uint)(shdr->sh_size) / st_entsize;
 103
 104         /* Get string table. */
 105         shdr = shdrs + (swap_uint32(shdr->sh_link) * sh_entsize);
 106         strtab = vdso + FUNC(swap_uint)(shdr->sh_offset);
 107
 108         /* Write offsets for symbols needed by the kernel. */
 109         for (i = 0; vdso_symbols[i].name; i++) {
 110                 if (!(vdso_symbols[i].abis & elf_abi))
 111                         continue;
 112
 113                 for (j = 0; j < st_count; j++) {
 114                         sym = symtab + (j * st_entsize);
 115                         name = strtab + swap_uint32(sym->st_name);
 116
 117                         if (!strcmp(name, vdso_symbols[i].name)) {
 118                                 offset = FUNC(swap_uint)(sym->st_value);
 119
 120                                 fprintf(out_file,
 121                                         "\t.%s = 0x%" PRIx64 ",\n",
 122                                         vdso_symbols[i].offset_name, offset);
 123                                 break;
 124                         }
 125                 }
 126
 127                 if (j == st_count) {
 128                         fprintf(stderr,
 129                                 "%s: '%s' is missing required symbol '%s'\n",
 130                                 program_name, path, vdso_symbols[i].name);
 131                         return false;
 132                 }
 133         }
 134
 135         return true;
 136 }