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px4-firmware/nuttx/binfmt/libelf/libelf_bind.c

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/****************************************************************************
* binfmt/libelf/libelf_bind.c
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
* COPYRIGHT OWNER 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <string.h>
#include <elf32.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/binfmt/elf.h>
#include <nuttx/binfmt/symtab.h>
#include "libelf.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* CONFIG_DEBUG, CONFIG_DEBUG_VERBOSE, and CONFIG_DEBUG_BINFMT have to be
* defined or CONFIG_ELF_DUMPBUFFER does nothing.
*/
#if !defined(CONFIG_DEBUG_VERBOSE) || !defined (CONFIG_DEBUG_BINFMT)
# undef CONFIG_ELF_DUMPBUFFER
#endif
#ifndef CONFIG_ELF_BUFFERSIZE
# define CONFIG_ELF_BUFFERSIZE 128
#endif
#ifdef CONFIG_ELF_DUMPBUFFER
# define elf_dumpbuffer(m,b,n) bvdbgdumpbuffer(m,b,n)
#else
# define elf_dumpbuffer(m,b,n)
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: elf_readsym
*
* Description:
* Read the ELFT symbol structure at the specfied index into memory.
*
****************************************************************************/
static inline int elf_readrel(FAR struct elf_loadinfo_s *loadinfo,
FAR const Elf32_Shdr *relsec,
int index, FAR Elf32_Rel *rel)
{
off_t offset;
/* Verify that the symbol table index lies within symbol table */
if (index < 0 || index > (relsec->sh_size / sizeof(Elf32_Rel)))
{
bdbg("Bad relocation symbol index: %d\n", index);
return -EINVAL;
}
/* Get the file offset to the symbol table entry */
offset = relsec->sh_offset + sizeof(Elf32_Rel) * index;
/* And, finally, read the symbol table entry into memory */
return elf_read(loadinfo, (FAR uint8_t*)rel, sizeof(Elf32_Rel), offset);
}
/****************************************************************************
* Name: elf_relocate and elf_relocateadd
*
* Description:
* Perform all relocations associated with a section.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static int elf_relocate(FAR struct elf_loadinfo_s *loadinfo, int relidx,
FAR const struct symtab_s *exports, int nexports)
{
FAR Elf32_Shdr *relsec = &loadinfo->shdr[relidx];
FAR Elf32_Shdr *dstsec = &loadinfo->shdr[relsec->sh_info];
Elf32_Rel rel;
Elf32_Sym sym;
uintptr_t addr;
int symidx;
int ret;
int i;
/* Examine each relocation in the section. 'relsec' is the section
* containing the relations. 'dstsec' is the section containing the data
* to be relocated.
*/
for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++)
{
/* Read the relocation entry into memory */
ret = elf_readrel(loadinfo, relsec, i, &rel);
if (ret < 0)
{
bdbg("Section %d reloc %d: Failed to read relocation entry: %d\n",
relidx, i, ret);
return ret;
}
/* Get the symbol table index for the relocation. This is contained
* in a bit-field within the r_info element.
*/
symidx = ELF32_R_SYM(rel.r_info);
/* Read the symbol table entry into memory */
ret = elf_readsym(loadinfo, symidx, &sym);
if (ret < 0)
{
bdbg("Section %d reloc %d: Failed to read symbol[%d]: %d\n",
relidx, i, symidx, ret);
return ret;
}
/* Get the value of the symbol (in sym.st_value) */
ret = elf_symvalue(loadinfo, &sym, exports, nexports);
if (ret < 0)
{
bdbg("Section %d reloc %d: Failed to get value of symbol[%d]: %d\n",
relidx, i, symidx, ret);
return ret;
}
/* Calculate the relocation address */
if (rel.r_offset < 0 || rel.r_offset > dstsec->sh_size - sizeof(uint32_t))
{
bdbg("Section %d reloc %d: Relocation address out of range, offset %d size %d\n",
relidx, i, rel.r_offset, dstsec->sh_size);
return -EINVAL;
}
addr = dstsec->sh_addr + rel.r_offset;
/* Now perform the architecture-specific relocation */
ret = arch_relocate(&rel, &sym, addr);
if (ret < 0)
{
bdbg("Section %d reloc %d: Relocation failed: %d\n", ret);
return ret;
}
}
return OK;
}
static int elf_relocateadd(FAR struct elf_loadinfo_s *loadinfo, int relidx,
FAR const struct symtab_s *exports, int nexports)
{
bdbg("Not implemented\n");
return -ENOSYS;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: elf_bind
*
* Description:
* Bind the imported symbol names in the loaded module described by
* 'loadinfo' using the exported symbol values provided by 'symtab'.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_bind(FAR struct elf_loadinfo_s *loadinfo,
FAR const struct symtab_s *exports, int nexports)
{
int ret;
int i;
/* Find the symbol and string tables */
ret = elf_findsymtab(loadinfo);
if (ret < 0)
{
return ret;
}
/* Allocate an I/O buffer. This buffer is used by elf_symname() to
* accumulate the variable length symbol name.
*/
ret = elf_allocbuffer(loadinfo);
if (ret < 0)
{
bdbg("elf_allocbuffer failed: %d\n", ret);
return -ENOMEM;
}
/* Process relocations in every allocated section */
for (i = 1; i < loadinfo->ehdr.e_shnum; i++)
{
/* Get the index to the relocation section */
int infosec = loadinfo->shdr[i].sh_info;
if (infosec >= loadinfo->ehdr.e_shnum)
{
continue;
}
/* Make sure that the section is allocated. We can't relocated
* sections that were not loaded into memory.
*/
if ((loadinfo->shdr[infosec].sh_flags & SHF_ALLOC) == 0)
{
continue;
}
/* Process the relocations by type */
if (loadinfo->shdr[i].sh_type == SHT_REL)
{
ret = elf_relocate(loadinfo, i, exports, nexports);
}
else if (loadinfo->shdr[i].sh_type == SHT_RELA)
{
ret = elf_relocateadd(loadinfo, i, exports, nexports);
}
if (ret < 0)
{
break;
}
}
/* Flush the instruction cache before starting the newly loaded module */
#ifdef CONFIG_ELF_ICACHE
arch_flushicache((FAR void*)loadinfo->elfalloc, loadinfo->elfsize);
#endif
return ret;
}
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