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Finishes basic coding of ELF file support

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5259 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2012-10-25 19:21:47 +00:00
parent 86618a177b
commit 87e9dbc4c8
9 changed files with 493 additions and 11 deletions
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17
binfmt/libelf/Kconfig
View file

@ -15,6 +15,23 @@ config ELF_STACKSIZE
---help---
This is the default stack size that will will be used when starting ELF binaries.
config ELF_BUFFERSIZE
int "ELF I/O Buffer Size"
default 128
---help---
This is an I/O buffer that is used to access the ELF file. Variable length items
will need to be read (such as symbol names). This is really just this initial
size of the buffer; it will be reallocated as necessary to hold large symbol
names). Default: 128
config ELF_BUFFERINCR
int "ELF I/O Buffer Realloc Increment"
default 32
---help---
This is an I/O buffer that is used to access the ELF file. Variable length items
will need to be read (such as symbol names). This value specifies the size
increment to use each time the buffer is reallocated. Default: 32
config ELF_CONSTRUCTORS
bool "C++ Static Constructor Support"
default n

4
binfmt/libelf/Make.defs
View file

@ -45,6 +45,10 @@ BINFMT_CSRCS = libelf_init.c libelf_uninit.c libelf_load.c \
libelf_unload.c libelf_verify.c libelf_read.c \
libelf_bind.c libelf_symbols.c
ifeq ($(CONFIG_ELF_CONSTRUCTORS),y)
BINFMT_CSRCS += libelf_ctors.c
endif
# Hook the libelf subdirectory into the build
VPATH += libelf

69
binfmt/libelf/libelf.h
View file

@ -105,9 +105,78 @@ int elf_findsymtab(FAR struct elf_loadinfo_s *loadinfo);
* Description:
* Read the ELFT symbol structure at the specfied index into memory.
*
* Input Parameters:
* loadinfo - Load state information
* index - Symbol table index
* sym - Location to return the table entry
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_readsym(FAR struct elf_loadinfo_s *loadinfo, int index,
FAR Elf32_Sym *sym);
/****************************************************************************
* Name: elf_symvalue
*
* Description:
* Get the value of a symbol. The updated value of the symbol is returned
* in the st_value field of the symbol table entry.
*
* Input Parameters:
* loadinfo - Load state information
* sym - Symbol table entry (value might be undefined)
* exports - The symbol table to use for resolving undefined symbols.
* nexports - Number of symbols in the symbol table.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_symvalue(FAR struct elf_loadinfo_s *loadinfo, FAR Elf32_Sym *sym,
FAR const struct symtab_s *exports, int nexports);
/****************************************************************************
* Name: elf_findctors
*
* Description:
* Find C++ static constructors.
*
* Input Parameters:
* loadinfo - Load state information
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
#ifdef CONFIG_ELF_CONSTRUCTORS
int elf_findctors(FAR struct elf_loadinfo_s *loadinfo);
#endif
/****************************************************************************
* Name: elf_doctors
*
* Description:
* Execute C++ static constructors.
*
* Input Parameters:
* loadinfo - Load state information
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
#ifdef CONFIG_ELF_CONSTRUCTORS
int elf_doctors(FAR struct elf_loadinfo_s *loadinfo);
#endif
#endif /* __BINFMT_LIBELF_LIBELF_H */

44
binfmt/libelf/libelf_bind.c
View file

@ -46,6 +46,7 @@
#include <assert.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/binfmt/elf.h>
#include <nuttx/binfmt/symtab.h>
@ -63,6 +64,10 @@
# 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
@ -124,7 +129,9 @@ static inline int elf_readrel(FAR struct elf_loadinfo_s *loadinfo,
*
****************************************************************************/
static int elf_relocate(FAR struct elf_loadinfo_s *loadinfo, int relidx)
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];
@ -165,6 +172,16 @@ static int elf_relocate(FAR struct elf_loadinfo_s *loadinfo, int relidx)
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))
@ -189,7 +206,8 @@ static int elf_relocate(FAR struct elf_loadinfo_s *loadinfo, int relidx)
return OK;
}
static int elf_relocateadd(FAR struct elf_loadinfo_s *loadinfo, int relidx)
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;
@ -226,6 +244,18 @@ int elf_bind(FAR struct elf_loadinfo_s *loadinfo,
return ret;
}
/* Allocate an I/O buffer. This buffer is used only by elf_symname() to
* accumulate the variable length symbol name.
*/
loadinfo->iobuffer = (FAR uint8_t *)kmalloc(CONFIG_ELF_BUFFERSIZE);
if (!loadinfo->iobuffer)
{
bdbg("Failed to allocate an I/O buffer\n");
return -ENOMEM;
}
loadinfo->buflen = CONFIG_ELF_BUFFERSIZE;
/* Process relocations in every allocated section */
for (i = 1; i < loadinfo->ehdr.e_shnum; i++)
@ -251,11 +281,11 @@ int elf_bind(FAR struct elf_loadinfo_s *loadinfo,
if (loadinfo->shdr[i].sh_type == SHT_REL)
{
ret = elf_relocate(loadinfo, i);
ret = elf_relocate(loadinfo, i, exports, nexports);
}
else if (loadinfo->shdr[i].sh_type == SHT_RELA)
{
ret = elf_relocateadd(loadinfo, i);
ret = elf_relocateadd(loadinfo, i, exports, nexports);
}
if (ret < 0)
@ -269,6 +299,12 @@ int elf_bind(FAR struct elf_loadinfo_s *loadinfo,
#ifdef CONFIG_ELF_ICACHE
arch_flushicache((FAR void*)loadinfo->alloc, loadinfo->allocsize);
#endif
/* Free the I/O buffer */
kfree(loadinfo->iobuffer);
loadinfo->iobuffer = NULL;
loadinfo->buflen = 0;
return ret;
}

134
binfmt/libelf/libelf_ctors.c Normal file
View file

@ -0,0 +1,134 @@
/****************************************************************************
* binfmt/libelf/libelf_ctors.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 <debug.h>
#include <nuttx/binfmt/elf.h>
#include "libelf"
#ifdef CONFIG_ELF_CONSTRUCTORS
/****************************************************************************
* Pre-Processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
typedef FAR void (*ctor_t)(void);
/****************************************************************************
* Private Constant Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: elf_findctors
*
* Description:
* Find C++ static constructors.
*
* Input Parameters:
* loadinfo - Load state information
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_findctors(FAR struct elf_loadinfo_s *loadinfo)
{
/* Search through the shdr[] array in loadinfo for a section named .ctors */
#warning "Missing logic"
/* Get the address of the beginning of the constructros from the sh_addr
* field of the section. Save that in the ctors field of the loadinfo
* structure.
*/
#warning "Missing logic"
/* Get the number of constructors from the sh_size field of the section.
* Save that number in the nctors field of the loadinfo structure.
*/
#warning "Missing logic"
return -ENOSYS;
}
/****************************************************************************
* Name: elf_doctors
*
* Description:
* Execute C++ static constructors.
*
* Input Parameters:
* loadinfo - Load state information
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_doctors(FAR struct elf_loadinfo_s *loadinfo)
{
ctor_t ctor = (ctor_t)loadinfo->ctors;
int i;
/* Execute each constructor */
for (i = 0; i < loadinfo->nctors; i++)
{
ctor();
ctor++;
}
}
#endif /* CONFIG_ELF_CONSTRUCTORS

12
binfmt/libelf/libelf_load.c
View file

@ -327,6 +327,7 @@ int elf_load(FAR struct elf_loadinfo_s *loadinfo)
ret = elf_filelen(loadinfo);
{
bdbg("elf_filelen failed: %d\n", ret);
return ret;
}
@ -335,6 +336,7 @@ int elf_load(FAR struct elf_loadinfo_s *loadinfo)
ret = elf_loadshdrs(loadinfo);
if (ret < 0)
{
bdbg("elf_loadshdrs failed: %d\n", ret);
return ret;
}
@ -347,11 +349,19 @@ int elf_load(FAR struct elf_loadinfo_s *loadinfo)
ret = elf_loadfile(loadinfo);
if (ret < 0)
{
bdbg("elf_loadfile failed: %d\n", ret);
goto errout_with_shdrs;
}
/* Find static constructors. */
#warning "Missing logic"
#ifdef CONFIG_ELF_CONSTRUCTORS
ret = elf_findctors(loadinfo);
{
bdbg("elf_findctors failed: %d\n", ret);
goto errout_with_shdrs;
}
#endif
return OK;

204
binfmt/libelf/libelf_symbols.c
View file

@ -39,11 +39,14 @@
#include <nuttx/config.h>
#include <stdlib.h>
#include <string.h>
#include <elf.h>
#include <debug.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/binfmt/elf.h>
#include <nuttx/binfmt/symtab.h>
#include "libelf.h"
@ -51,6 +54,10 @@
* Pre-Processor Definitions
****************************************************************************/
#ifndef CONFIG_ELF_BUFFERINCR
# define CONFIG_ELF_BUFFERINCR 32
#endif
/****************************************************************************
* Private Constant Data
****************************************************************************/
@ -59,6 +66,101 @@
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: elf_symname
*
* Description:
* Get the symbol name in loadinfo->iobuffer[].
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static int elf_symname(FAR struct elf_loadinfo_s *loadinfo,
FAR const Elf32_Sym *sym)
{
FAR uint8_t *buffer;
off_t offset;
size_t readlen;
size_t bytesread;
int ret;
/* Get the file offset to the string that is the name of the symbol. The
* st_name member holds an offset into the file's symbol string table.
*/
if (sym->st_name == 0)
{
bdbg("Symbol has no name\n");
return -ENOENT;
}
offset = loadinfo->shdr[loadinfo->strtabidx].sh_offset + sym->st_name;
/* Loop until we get the entire symbol name into memory */
buffer = loadinfo->iobuffer;
bytesread = 0;
for (;;)
{
/* Get the number of bytes to read */
readlen = loadinfo->buflen - bytesread;
if (offset + readlen > loadinfo->filelen)
{
readlen = loadinfo->filelen - offset;
if (readlen <= 0)
{
bdbg("At end of file\n");
return -EINVAL;
}
}
/* Read that number of bytes into the array */
buffer = &loadinfo->iobuffer[bytesread];
ret = elf_read(loadinfo, buffer, readlen, offset);
if (ret < 0)
{
bdbg("Failed to read symbol name\n");
return ret;
}
bytesread += readlen;
/* Did we read the NUL terminator? */
if (memchr(buffer, '\0', readlen) != NULL)
{
/* Yes, the buffer contains a NUL terminator. */
return OK;
}
/* No.. then we have to read more */
buffer = realloc((FAR void *)loadinfo->iobuffer,
loadinfo->buflen + CONFIG_ELF_BUFFERINCR);
if (!buffer)
{
bdbg("Failed to reallocate the I/O buffer\n");
return -ENOMEM;
}
/* Save the new buffer info */
loadinfo->iobuffer = buffer;
loadinfo->buflen += CONFIG_ELF_BUFFERINCR;
}
/* We will not get here */
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
@ -108,6 +210,15 @@ int elf_findsymtab(FAR struct elf_loadinfo_s *loadinfo)
* Description:
* Read the ELFT symbol structure at the specfied index into memory.
*
* Input Parameters:
* loadinfo - Load state information
* index - Symbol table index
* sym - Location to return the table entry
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_readsym(FAR struct elf_loadinfo_s *loadinfo, int index,
@ -132,3 +243,94 @@ int elf_readsym(FAR struct elf_loadinfo_s *loadinfo, int index,
return elf_read(loadinfo, (FAR uint8_t*)sym, sizeof(Elf32_Sym), offset);
}
/****************************************************************************
* Name: elf_symvalue
*
* Description:
* Get the value of a symbol. The updated value of the symbol is returned
* in the st_value field of the symbol table entry.
*
* Input Parameters:
* loadinfo - Load state information
* sym - Symbol table entry (value might be undefined)
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_symvalue(FAR struct elf_loadinfo_s *loadinfo, FAR Elf32_Sym *sym,
FAR const struct symtab_s *exports, int nexports)
{
FAR const struct symtab_s *symbol;
uintptr_t secbase;
int ret;
switch (sym->st_shndx)
{
case SHN_COMMON:
{
/* NuttX ELF modules should be compiled with -fno-common. */
bdbg("SHN_COMMON: Re-compile with -fno-common\n");
return -EINVAL;
}
case SHN_ABS:
{
/* st_value already holds the correct value */
bvdbg("SHN_ABS: st_value=%08lx\n", (long)sym->st_value);
return OK;
}
case SHN_UNDEF:
{
/* Get the name of the undefined symbol */
ret = elf_symname(loadinfo, sym);
if (ret < 0)
{
bdbg("SHN_UNDEF: Failed to get symbol name: %d\n", ret);
return ret;
}
/* Check if the base code exports a symbol of this name */
#ifdef CONFIG_SYMTAB_ORDEREDBYNAME
symbol = symtab_findorderedbyname(exports, (FAR char *)loadinfo->iobuffer, nexports);
#else
symbol = symtab_findbyname(exports, (FAR char *)loadinfo->iobuffer, nexports);
#endif
if (!symbol)
{
bdbg("SHN_UNDEF: Exported symbol \"%s\" not found\n", loadinfo->iobuffer);
return -ENOENT;
}
/* Yes... add the exported symbol value to the ELF symbol table entry */
bvdbg("SHN_ABS: name=%s %08x+%08x=%08x\n",
loadinfo->iobuffer, sym->st_value, symbol->sym_value,
sym->st_value + symbol->sym_value);
sym->st_value += (Elf32_Word)((uintptr_t)symbol->sym_value);
}
break;
default:
{
secbase = loadinfo->shdr[sym->st_shndx].sh_addr;
bvdbg("Other: %08x+%08x=%08x\n",
sym->st_value, secbase, sym->st_value + secbase);
sym->st_value += secbase;
}
break;
}
return OK;
}

11
binfmt/libelf/libelf_unload.c
View file

@ -80,17 +80,24 @@ int elf_unload(struct elf_loadinfo_s *loadinfo)
if (loadinfo->alloc)
{
kfree((void*)loadinfo->alloc);
kfree((FAR void *)loadinfo->alloc);
loadinfo->alloc = 0;
loadinfo->allocsize = 0;
}
if (loadinfo->shdr)
{
kfree((void*)loadinfo->shdr);
kfree((FAR void *)loadinfo->shdr);
loadinfo->shdr = NULL;
}
if (loadinfo->iobuffer)
{
kfree((FAR void *)loadinfo->iobuffer);
loadinfo->iobuffer = NULL;
loadinfo->buflen = 0;
}
return OK;
}

9
include/nuttx/binfmt/elf.h
View file

@ -69,14 +69,17 @@ struct elf_loadinfo_s
uintptr_t alloc; /* Allocated memory with the ELF file is loaded */
size_t allocsize; /* Size of the memory allocation */
off_t filelen; /* Length of the entire ELF file */
#ifdef CONFIG_ELF_CONSTRUCTORS
uintptr_t ctors; /* Static constructors */
#endif
int filfd; /* Descriptor for the file being loaded */
#ifdef CONFIG_ELF_CONSTRUCTORS
uintptr_t ctors; /* Location of static constructors in memory */
uint16_t nctors; /* Number of constructors */
#endif
uint16_t symtabidx; /* Symbol table section index */
uint16_t strtabidx; /* String table section index */
uint16_t buflen; /* size of iobuffer[] */
Elf32_Ehdr ehdr; /* Buffered ELF file header */
FAR Elf32_Shdr *shdr; /* Buffered ELF section headers */
uint8_t *iobuffer; /* File I/O buffer */
};
/****************************************************************************