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

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/****************************************************************************
* binfmt/libelf/libelf_load.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 <sys/types.h>
#include <sys/stat.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <elf.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/binfmt/elf.h>
#include "libelf.h"
/****************************************************************************
* Pre-Processor Definitions
****************************************************************************/
#define ELF_ALIGN_MASK ((1 << CONFIG_ELF_ALIGN_LOG2) - 1)
#define ELF_ALIGNUP(a) (((unsigned long)(a) + ELF_ALIGN_MASK) & ~ELF_ALIGN_MASK)
#define ELF_ALIGNDOWN(a) ((unsigned long)(a) & ~ELF_ALIGN_MASK)
#ifndef MAX
#define MAX(x,y) ((x) > (y) ? (x) : (y))
#endif
/****************************************************************************
* Private Constant Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: elf_filelen
*
* Description:
* Get the size of the ELF file
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static inline int elf_filelen(FAR struct elf_loadinfo_s *loadinfo)
{
struct stat buf;
int ret;
/* Get the file stats */
ret = fstat(loadinfo->filfd, &buf);
if (ret < 0)
{
int errval = errno;
bdbg("Failed to fstat file: %d\n", errval);
return -errval;
}
/* Verify that it is a regular file */
if (!S_ISREG(buf.st_mode))
{
bdbg("Not a regular file. mode: %d\n", buf.st_mode);
return -ENOENT;
}
/* TODO: Verify that the file is readable */
/* Return the size of the file in the loadinfo structure */
loadinfo->filelen = buf.st_size;
return OK;
}
/****************************************************************************
* Name: elf_loadshdrs
*
* Description:
* Loads section headers into memory.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static inline int elf_loadshdrs(FAR struct elf_loadinfo_s *loadinfo)
{
size_t shdrsize;
int ret;
DEBUGASSERT(loadinfo->shdr == NULL);
/* Verify that there are sections */
if (loadinfo->ehdr.e_shnum < 1)
{
bdbg("No sections(?)\n");
return -EINVAL;
}
/* Get the total size of the section header table */
shdrsize = (size_t)loadinfo->ehdr.e_shentsize * (size_t)loadinfo->ehdr.e_shnum;
if(loadinfo->ehdr.e_shoff + shdrsize > loadinfo->filelen)
{
bdbg("Insufficent space in file for section header table\n");
return -ESPIPE;
}
/* Allocate memory to hold a working copy of the sector header table */
loadinfo->shdr = (FAR Elf32_Shdr*)kmalloc(shdrsize);
if (!loadinfo->shdr)
{
bdbg("Failed to allocate the section header table. Size: %ld\n", (long)shdrsize);
return -ENOMEM;
}
/* Read the section header table into memory */
ret = elf_read(loadinfo, (FAR uint8_t*)loadinfo->shdr, shdrsize, loadinfo->ehdr.e_shoff);
if (ret < 0)
{
bdbg("Failed to read section header table: %d\n", ret);
goto errout_with_alloc;
}
return OK;
errout_with_alloc:
kfree(loadinfo->shdr);
loadinfo->shdr = 0;
return ret;
}
/****************************************************************************
* Name: elf_allocsize
*
* Description:
* Calculate total memory allocation for the ELF file.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static void elf_allocsize(struct elf_loadinfo_s *loadinfo)
{
size_t allocsize;
int i;
/* Accumulate the size each section into memory that is marked SHF_ALLOC */
allocsize = 0;
for (i = 0; i < loadinfo->ehdr.e_shnum; i++)
{
FAR Elf32_Shdr *shdr = &loadinfo->shdr[i];
/* SHF_ALLOC indicates that the section requires memory during
* execution.
*/
if ((shdr->sh_flags & SHF_ALLOC) != 0)
{
allocsize += ELF_ALIGNUP(shdr->sh_size);
}
}
/* Save the allocation size */
loadinfo->allocsize = allocsize;
}
/****************************************************************************
* Name: elf_loadfile
*
* Description:
* Allocate memory for the file and read the section data into the
* allocated memory. Section addresses in the shdr[] are updated to point
* to the corresponding position in the allocated memory.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static inline int elf_loadfile(FAR struct elf_loadinfo_s *loadinfo)
{
FAR uint8_t *dest;
int ret;
int i;
/* Allocate (and zero) memory for the ELF file. */
loadinfo->alloc = (uintptr_t)kzalloc(loadinfo->allocsize);
if (!loadinfo->alloc)
{
return -ENOMEM;
}
/* Read each section into memory that is marked SHF_ALLOC + SHT_NOBITS */
bvdbg("Loaded sections:\n");
dest = (FAR uint8_t*)loadinfo->alloc;
for (i = 0; i < loadinfo->ehdr.e_shnum; i++)
{
FAR Elf32_Shdr *shdr = &loadinfo->shdr[i];
/* SHF_ALLOC indicates that the section requires memory during
* execution */
if ((shdr->sh_flags & SHF_ALLOC) == 0)
{
continue;
}
/* SHT_NOBITS indicates that there is no data in the file for the
* section.
*/
if (shdr->sh_type != SHT_NOBITS)
{
/* Read the section data from sh_offset to dest */
ret = elf_read(loadinfo, dest, shdr->sh_size, shdr->sh_offset);
if (ret < 0)
{
bdbg("Failed to read section %d: %d\n", i, ret);
goto errout_with_alloc;
}
}
/* Update sh_addr to point to copy in memory */
bvdbg("%d. %08x->%08x\n", i, (long)shdr->sh_addr, (long)dest);
shdr->sh_addr = (uintptr_t)dest;
/* Setup the memory pointer for the next time through the loop */
dest += ELF_ALIGNUP(shdr->sh_size);
}
return OK;
errout_with_alloc:
kfree((FAR void*)loadinfo->alloc);
loadinfo->alloc = 0;
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: elf_load
*
* Description:
* Loads the binary into memory, allocating memory, performing relocations
* and inializing the data and bss segments.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_load(FAR struct elf_loadinfo_s *loadinfo)
{
int ret;
bvdbg("loadinfo: %p\n", loadinfo);
DEBUGASSERT(loadinfo && loadinfo->filfd >= 0);
/* Get the length of the file. */
ret = elf_filelen(loadinfo);
{
bdbg("elf_filelen failed: %d\n", ret);
return ret;
}
/* Load section headers into memory */
ret = elf_loadshdrs(loadinfo);
if (ret < 0)
{
bdbg("elf_loadshdrs failed: %d\n", ret);
return ret;
}
/* Determine total size to allocate */
elf_allocsize(loadinfo);
/* Allocate memory and load sections into memory */
ret = elf_loadfile(loadinfo);
if (ret < 0)
{
bdbg("elf_loadfile failed: %d\n", ret);
goto errout_with_shdrs;
}
/* Find static constructors. */
#ifdef CONFIG_ELF_CONSTRUCTORS
ret = elf_findctors(loadinfo);
{
bdbg("elf_findctors failed: %d\n", ret);
goto errout_with_shdrs;
}
#endif
return OK;
/* Error exits */
errout_with_shdrs:
kfree(loadinfo->shdr);
loadinfo->shdr = NULL;
return ret;
}
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