sys/lib/libsa/lookup_elf32.c

   1 /* $NetBSD: lookup_elf32.c,v 1.3 2010/02/11 21:28:16 martin Exp $ */
   2
   3 /*-
   4  * Copyright (c) 2010 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Martin Husemann.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /* If not included by lookup_elf64.c, ELFSIZE won't be defined. */
  33 #ifndef ELFSIZE
  34 #define ELFSIZE 32
  35 #endif
  36
  37 #include <lib/libkern/libkern.h>
  38 #include <sys/param.h>
  39 #include <sys/exec_elf.h>
  40
  41 #if ((ELFSIZE == 32) && defined(BOOT_ELF32)) || \
  42     ((ELFSIZE == 64) && defined(BOOT_ELF64))
  43
  44 void * ELFNAMEEND(lookup_symbol)(const char *, void *, void *);
  45
  46 void *
  47 ELFNAMEEND(lookup_symbol)(const char *symname, void *sstab, void *estab)
  48 {
  49         Elf_Ehdr *elf;
  50         Elf_Shdr *shp;
  51         Elf_Sym *symtab_start, *symtab_end, *sp;
  52         char *strtab_start, *strtab_end;
  53         int i, j;
  54
  55         elf = sstab;
  56         if (elf->e_shoff == 0)
  57                 return NULL;
  58
  59         switch (elf->e_machine) {
  60         ELFDEFNNAME(MACHDEP_ID_CASES)
  61         default:
  62                 return NULL;
  63         }
  64
  65         symtab_start = symtab_end = NULL;
  66         strtab_start = strtab_end = NULL;
  67
  68         shp = (Elf_Shdr *)((char *)sstab + elf->e_shoff);
  69         for (i = 0; i < elf->e_shnum; i++) {
  70                 if (shp[i].sh_type != SHT_SYMTAB)
  71                         continue;
  72                 if (shp[i].sh_offset == 0)
  73                         continue;
  74                 symtab_start = (Elf_Sym*)((char*)sstab + shp[i].sh_offset);
  75                 symtab_end = (Elf_Sym*)((char*)sstab + shp[i].sh_offset
  76                         + shp[i].sh_size);
  77                 j = shp[i].sh_link;
  78                 if (shp[j].sh_offset == 0)
  79                         continue;
  80                 strtab_start = (char*)sstab + shp[j].sh_offset;
  81                 strtab_end = (char*)sstab + shp[j].sh_offset + shp[j].sh_size;
  82                 break;
  83         }
  84
  85         if (!symtab_start || !strtab_start)
  86                 return NULL;
  87
  88         for (sp = symtab_start; sp < symtab_end; sp++)
  89                 if (sp->st_name != 0 &&
  90                     strcmp(strtab_start + sp->st_name, symname) == 0)
  91                         return (void*)(uintptr_t)sp->st_value;
  92
  93         return NULL;
  94 }
  95
  96 #endif /* (ELFSIZE == 32 && BOOT_ELF32) || (ELFSIZE == 64 && BOOT_ELF64) */