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Utility function to lookup a symbol value in an elf symbol table - allows, 

for example, a bootloader to access symbols in the just loaded kernel
(or module).
This commit is contained in:
martin 2010-02-10 21:54:47 +00:00
parent 1caeee472f
commit 9b40c0f8c3
3 changed files with 130 additions and 3 deletions
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6
sys/lib/libsa/Makefile
View File

@ -1,4 +1,4 @@
# $NetBSD: Makefile,v 1.70 2009/08/25 14:10:54 he Exp $
# $NetBSD: Makefile,v 1.71 2010/02/10 21:54:47 martin Exp $
LIB= sa
NOPIC= # defined
@ -45,8 +45,8 @@ SRCS+= cread.c
.endif
.if (${SA_USE_LOADFILE} == "yes")
SRCS+= loadfile.c loadfile_ecoff.c loadfile_elf32.c \
loadfile_elf64.c
SRCS+= loadfile.c loadfile_ecoff.c loadfile_elf32.c lookup_elf32.c \
loadfile_elf64.c lookup_elf64.c
.if (${MACHINE_CPU} != "mips")
SRCS+= loadfile_aout.c
.endif

94
sys/lib/libsa/lookup_elf32.c Normal file
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@ -0,0 +1,94 @@
/* $NetBSD: lookup_elf32.c,v 1.1 2010/02/10 21:54:47 martin Exp $ */
/*-
* Copyright (c) 2010 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Martin Husemann.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/* If not included by lookup_elf64.c, ELFSIZE won't be defined. */
#ifndef ELFSIZE
#define ELFSIZE 32
#endif
#include <string.h>
#include <sys/param.h>
#include <sys/exec_elf.h>
#if ((ELFSIZE == 32) && defined(BOOT_ELF32)) || \
((ELFSIZE == 64) && defined(BOOT_ELF64))
void *
ELFNAMEEND(lookup_symbol)(const char *symname, void *sstab, void *estab)
{
Elf_Ehdr *elf;
Elf_Shdr *shp;
Elf_Sym *symtab_start, *symtab_end, *sp;
char *strtab_start, *strtab_end;
int i, j;
elf = sstab;
if (elf->e_shoff == 0)
return NULL;
switch (elf->e_machine) {
ELFDEFNNAME(MACHDEP_ID_CASES)
default:
return NULL;
}
symtab_start = symtab_end = NULL;
strtab_start = strtab_end = NULL;
shp = (Elf_Shdr *)((char *)sstab + elf->e_shoff);
for (i = 0; i < elf->e_shnum; i++) {
if (shp[i].sh_type != SHT_SYMTAB)
continue;
if (shp[i].sh_offset == 0)
continue;
symtab_start = (Elf_Sym*)((char*)sstab + shp[i].sh_offset);
symtab_end = (Elf_Sym*)((char*)sstab + shp[i].sh_offset
+ shp[i].sh_size);
j = shp[i].sh_link;
if (shp[j].sh_offset == 0)
continue;
strtab_start = (char*)sstab + shp[j].sh_offset;
strtab_end = (char*)sstab + shp[j].sh_offset + shp[j].sh_size;
break;
}
if (!symtab_start || !strtab_start)
return NULL;
for (sp = symtab_start; sp < symtab_end; sp++)
if (sp->st_name != 0 &&
strcmp(strtab_start + sp->st_name, symname) == 0)
return (void*)(uintptr_t)sp->st_value;
return NULL;
}
#endif /* (ELFSIZE == 32 && BOOT_ELF32) || (ELFSIZE == 64 && BOOT_ELF64) */

33
sys/lib/libsa/lookup_elf64.c Normal file
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@ -0,0 +1,33 @@
/* $NetBSD: lookup_elf64.c,v 1.1 2010/02/10 21:54:47 martin Exp $ */
/*-
* Copyright (c) 2010 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Martin Husemann.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#define ELFSIZE 64
#include "lookup_elf32.c"