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rockbox/utils/imxtools/sbtools/elf.c
Amaury Pouly 1c14041041 sbtoelf: implement elf simplification 
Change-Id: Icfac5a2aa6a7b3582054321df003c6bb217b59d0
2012-11-28 00:06:31 +01:00

670 lines
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2011 Amaury Pouly
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "elf.h"
#include "misc.h"
/**
* Definitions
* taken from elf.h linux header
* based on ELF specification
* based on ARM ELF specification
*/
typedef uint16_t Elf32_Half;
typedef uint32_t Elf32_Word;
typedef int32_t Elf32_Sword;
typedef uint32_t Elf32_Addr;
typedef uint32_t Elf32_Off;
typedef uint16_t Elf32_Section;
#define EI_NIDENT 16
typedef struct
{
unsigned char e_ident[EI_NIDENT]; /* Magic number and other info */
Elf32_Half e_type; /* Object file type */
Elf32_Half e_machine; /* Architecture */
Elf32_Word e_version; /* Object file version */
Elf32_Addr e_entry; /* Entry point virtual address */
Elf32_Off e_phoff; /* Program header table file offset */
Elf32_Off e_shoff; /* Section header table file offset */
Elf32_Word e_flags; /* Processor-specific flags */
Elf32_Half e_ehsize; /* ELF header size in bytes */
Elf32_Half e_phentsize; /* Program header table entry size */
Elf32_Half e_phnum; /* Program header table entry count */
Elf32_Half e_shentsize; /* Section header table entry size */
Elf32_Half e_shnum; /* Section header table entry count */
Elf32_Half e_shstrndx; /* Section header string table index */
}Elf32_Ehdr;
#define EI_MAG0 0 /* File identification byte 0 index */
#define ELFMAG0 0x7f /* Magic number byte 0 */
#define EI_MAG1 1 /* File identification byte 1 index */
#define ELFMAG1 'E' /* Magic number byte 1 */
#define EI_MAG2 2 /* File identification byte 2 index */
#define ELFMAG2 'L' /* Magic number byte 2 */
#define EI_MAG3 3 /* File identification byte 3 index */
#define ELFMAG3 'F' /* Magic number byte 3 */
#define EI_CLASS 4 /* File class byte index */
#define ELFCLASS32 1 /* 32-bit objects */
#define EI_DATA 5 /* Data encoding byte index */
#define ELFDATA2LSB 1 /* 2's complement, little endian */
#define EI_VERSION 6 /* File version byte index, Value must be EV_CURRENT */
#define EI_OSABI 7 /* OS ABI identification */
#define ELFOSABI_NONE 0 /* UNIX System V ABI */
#define ELFOSABI_ARM_AEABI 64 /* ARM EABI */
#define ELFOSABI_ARM 97 /* ARM */
#define EI_ABIVERSION 8 /* ABI version */
#define EI_PAD 9 /* Byte index of padding bytes */
#define ET_EXEC 2 /* Executable file */
#define EM_ARM 40 /* ARM */
#define EV_CURRENT 1 /* Current version */
#define EF_ARM_HASENTRY 0x00000002
#define SHN_UNDEF 0 /* Undefined section */
typedef struct
{
Elf32_Word sh_name; /* Section name (string tbl index) */
Elf32_Word sh_type; /* Section type */
Elf32_Word sh_flags; /* Section flags */
Elf32_Addr sh_addr; /* Section virtual addr at execution */
Elf32_Off sh_offset; /* Section file offset */
Elf32_Word sh_size; /* Section size in bytes */
Elf32_Word sh_link; /* Link to another section */
Elf32_Word sh_info; /* Additional section information */
Elf32_Word sh_addralign; /* Section alignment */
Elf32_Word sh_entsize; /* Entry size if section holds table */
}Elf32_Shdr;
#define SHT_NULL 0 /* Section header table entry unused */
#define SHT_PROGBITS 1 /* Program data */
#define SHT_SYMTAB 2 /* Symbol table */
#define SHT_STRTAB 3 /* String table */
#define SHT_RELA 4 /* Relocation entries with addends */
#define SHT_HASH 5 /* Symbol hash table */
#define SHT_DYNAMIC 6 /* Dynamic linking information */
#define SHT_NOTE 7 /* Notes */
#define SHT_NOBITS 8 /* Program space with no data (bss) */
#define SHT_REL 9 /* Relocation entries, no addends */
#define SHT_SHLIB 10 /* Reserved */
#define SHT_DYNSYM 11 /* Dynamic linker symbol table */
#define SHT_INIT_ARRAY 14 /* Array of constructors */
#define SHT_FINI_ARRAY 15 /* Array of destructors */
#define SHT_PREINIT_ARRAY 16 /* Array of pre-constructors */
#define SHT_GROUP 17 /* Section group */
#define SHT_SYMTAB_SHNDX 18 /* Extended section indeces */
#define SHT_NUM 19 /* Number of defined types. */
#define SHF_WRITE (1 << 0) /* Writable */
#define SHF_ALLOC (1 << 1) /* Occupies memory during execution */
#define SHF_EXECINSTR (1 << 2) /* Executable */
#define SHF_MERGE (1 << 4) /* Might be merged */
#define SHF_STRINGS (1 << 5) /* Contains nul-terminated strings */
typedef struct
{
Elf32_Word p_type; /* Segment type */
Elf32_Off p_offset; /* Segment file offset */
Elf32_Addr p_vaddr; /* Segment virtual address */
Elf32_Addr p_paddr; /* Segment physical address */
Elf32_Word p_filesz; /* Segment size in file */
Elf32_Word p_memsz; /* Segment size in memory */
Elf32_Word p_flags; /* Segment flags */
Elf32_Word p_align; /* Segment alignment */
}Elf32_Phdr;
#define PT_LOAD 1 /* Loadable program segment */
#define PF_X (1 << 0) /* Segment is executable */
#define PF_W (1 << 1) /* Segment is writable */
#define PF_R (1 << 2) /* Segment is readable */
void elf_init(struct elf_params_t *params)
{
memset(params, 0, sizeof(struct elf_params_t));
}
extern void *xmalloc(size_t s);
static struct elf_section_t *elf_add_section(struct elf_params_t *params)
{
struct elf_section_t *sec = xmalloc(sizeof(struct elf_section_t));
if(params->first_section == NULL)
params->first_section = params->last_section = sec;
else
{
params->last_section->next = sec;
params->last_section = sec;
}
sec->next = NULL;
return sec;
}
static struct elf_segment_t *elf_add_segment(struct elf_params_t *params)
{
struct elf_segment_t *seg = xmalloc(sizeof(struct elf_section_t));
if(params->first_segment == NULL)
params->first_segment = params->last_segment = seg;
else
{
params->last_segment->next = seg;
params->last_segment = seg;
}
seg->next = NULL;
return seg;
}
void elf_add_load_section(struct elf_params_t *params,
uint32_t load_addr, uint32_t size, const void *section)
{
struct elf_section_t *sec = elf_add_section(params);
sec->type = EST_LOAD;
sec->addr = load_addr;
sec->size = size;
sec->section = xmalloc(size);
memcpy(sec->section, section, size);
}
void elf_add_fill_section(struct elf_params_t *params,
uint32_t fill_addr, uint32_t size, uint32_t pattern)
{
if(pattern != 0x00)
{
printf("oops, non-zero filling, ignore fill section\n");
return;
}
struct elf_section_t *sec = elf_add_section(params);
sec->type = EST_FILL;
sec->addr = fill_addr;
sec->size = size;
sec->pattern = pattern;
}
/* sort by increasing type and then increasing address */
static int elf_simplify_compare(const void *a, const void *b)
{
const struct elf_section_t *sa = a;
const struct elf_section_t *sb = b;
if(sa->type != sb->type)
return sa->type - sb->type;
return sa->addr - sb->addr;
}
void elf_simplify(struct elf_params_t *params)
{
/** find all sections of the same times which are contiguous and merge them */
/* count sections */
int nr_sections = 0;
struct elf_section_t *cur_sec = params->first_section;
while(cur_sec)
{
nr_sections++;
cur_sec = cur_sec->next;
}
/* put all sections in an array and free list */
struct elf_section_t *sections = malloc(sizeof(struct elf_section_t) * nr_sections);
cur_sec = params->first_section;
for(int i = 0; i < nr_sections; i++)
{
memcpy(&sections[i], cur_sec, sizeof(struct elf_section_t));
struct elf_section_t *old = cur_sec;
cur_sec = cur_sec->next;
free(old);
}
/* sort them by type and increasing addresses */
qsort(sections, nr_sections, sizeof(struct elf_section_t), &elf_simplify_compare);
/* merge them ! */
cur_sec = &sections[0];
for(int i = 1; i < nr_sections; i++)
{
/* different type => no */
if(sections[i].type != cur_sec->type)
goto Lnext;
/* (for fill) different pattern => no */
if(sections[i].type == EST_FILL && sections[i].pattern != cur_sec->pattern)
goto Lnext;
/* not contiguous => no */
if(sections[i].addr != cur_sec->addr + cur_sec->size)
goto Lnext;
/* merge !! */
if(sections[i].type == EST_FILL)
{
cur_sec->size += sections[i].size;
sections[i].size = 0; // will be ignored by rebuilding (see below)
}
else if(sections[i].type == EST_LOAD)
{
// merge data also
void *data = malloc(cur_sec->size + sections[i].size);
memcpy(data, cur_sec->section, cur_sec->size);
memcpy(data + cur_sec->size, sections[i].section, sections[i].size);
free(cur_sec->section);
free(sections[i].section);
cur_sec->section = data;
cur_sec->size += sections[i].size;
sections[i].size = 0; // will be ignored by rebuilding (see below)
}
continue;
/* update current section to consider */
Lnext:
cur_sec = &sections[i];
}
/* put back on a list and free array */
struct elf_section_t **prev_ptr = &params->first_section;
struct elf_section_t *prev_sec = NULL;
for(int i = 0; i < nr_sections; i++)
{
/* skip empty sections produced by simplification */
if(sections[i].size == 0)
continue;
struct elf_section_t *sec = malloc(sizeof(struct elf_section_t));
memcpy(sec, &sections[i], sizeof(struct elf_section_t));
*prev_ptr = sec;
prev_ptr = &sec->next;
prev_sec = sec;
}
*prev_ptr = NULL;
params->last_section = prev_sec;
free(sections);
}
void elf_write_file(struct elf_params_t *params, elf_write_fn_t write,
elf_printf_fn_t printf, void *user)
{
(void) printf;
Elf32_Ehdr ehdr;
uint32_t phnum = 0;
struct elf_section_t *sec = params->first_section;
uint32_t offset = 0;
Elf32_Phdr phdr;
Elf32_Shdr shdr;
memset(&ehdr, 0, EI_NIDENT);
while(sec)
{
if(sec->type == EST_LOAD)
{
sec->offset = offset;
offset += sec->size;
}
else
{
sec->offset = 0;
}
phnum++;
sec = sec->next;
}
uint32_t strtbl_offset = offset;
ehdr.e_ident[EI_MAG0] = ELFMAG0;
ehdr.e_ident[EI_MAG1] = ELFMAG1;
ehdr.e_ident[EI_MAG2] = ELFMAG2;
ehdr.e_ident[EI_MAG3] = ELFMAG3;
ehdr.e_ident[EI_CLASS] = ELFCLASS32;
ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
ehdr.e_ident[EI_VERSION] = EV_CURRENT;
ehdr.e_ident[EI_OSABI] = ELFOSABI_NONE;
ehdr.e_ident[EI_ABIVERSION] = 0;
ehdr.e_type = ET_EXEC;
ehdr.e_machine = EM_ARM;
ehdr.e_version = EV_CURRENT;
ehdr.e_entry = params->start_addr;
ehdr.e_flags = 0;
if(params->has_start_addr)
ehdr.e_flags |= EF_ARM_HASENTRY;
ehdr.e_ehsize = sizeof ehdr;
ehdr.e_phentsize = sizeof phdr;
ehdr.e_phnum = phnum;
ehdr.e_shentsize = sizeof shdr;
ehdr.e_shnum = phnum + 2; /* one for section 0 and one for string table */
ehdr.e_shstrndx = ehdr.e_shnum - 1;
ehdr.e_phoff = ehdr.e_ehsize;
ehdr.e_shoff = ehdr.e_ehsize + ehdr.e_phnum * ehdr.e_phentsize;
write(user, 0, &ehdr, sizeof ehdr);
/* allocate enough size to hold any combinaison of .text/.bss in the string table:
* - one empty name ("\0")
* - at most N names of the form ".textXXXX\0" or ".bssXXXX\0"
* - one name ".shstrtab\0" */
char *strtbl_content = malloc(1 + strlen(".shstrtab") + 1 +
phnum * (strlen(".textXXXX") + 1));
strtbl_content[0] = '\0';
strcpy(&strtbl_content[1], ".shstrtab");
uint32_t strtbl_index = 1 + strlen(".shstrtab") + 1;
uint32_t data_offset = ehdr.e_ehsize + ehdr.e_phnum * ehdr.e_phentsize +
ehdr.e_shnum * ehdr.e_shentsize;
sec = params->first_section;
offset = ehdr.e_phoff;
while(sec)
{
sec->offset += data_offset;
phdr.p_type = PT_LOAD;
if(sec->type == EST_LOAD)
phdr.p_offset = sec->offset;
else
phdr.p_offset = 0;
phdr.p_paddr = sec->addr;
phdr.p_vaddr = phdr.p_paddr; /* assume identity map ? */
phdr.p_memsz = sec->size;
if(sec->type == EST_LOAD)
phdr.p_filesz = phdr.p_memsz;
else
phdr.p_filesz = 0;
phdr.p_flags = PF_X | PF_W | PF_R;
phdr.p_align = 0;
write(user, offset, &phdr, sizeof phdr);
offset += sizeof(Elf32_Phdr);
sec = sec->next;
}
sec = params->first_section;
offset = ehdr.e_shoff;
{
shdr.sh_name = 0;
shdr.sh_type = SHT_NULL;
shdr.sh_flags = 0;
shdr.sh_addr = 0;
shdr.sh_offset = 0;
shdr.sh_size = 0;
shdr.sh_link = SHN_UNDEF;
shdr.sh_info = 0;
shdr.sh_addralign = 0;
shdr.sh_entsize = 0;
write(user, offset, &shdr, sizeof shdr);
offset += sizeof(Elf32_Shdr);
}
uint32_t text_idx = 0;
uint32_t bss_idx = 0;
while(sec)
{
shdr.sh_name = strtbl_index;
if(sec->type == EST_LOAD)
{
strtbl_index += 1 + sprintf(&strtbl_content[strtbl_index], ".text%d", text_idx++);
shdr.sh_type = SHT_PROGBITS;
}
else
{
strtbl_index += 1 + sprintf(&strtbl_content[strtbl_index], ".bss%d", bss_idx++);
shdr.sh_type = SHT_NOBITS;
}
shdr.sh_flags = SHF_ALLOC | SHF_EXECINSTR;
shdr.sh_addr = sec->addr;
shdr.sh_offset = sec->offset;
shdr.sh_size = sec->size;
shdr.sh_link = SHN_UNDEF;
shdr.sh_info = 0;
shdr.sh_addralign = 1;
shdr.sh_entsize = 0;
write(user, offset, &shdr, sizeof shdr);
offset += sizeof(Elf32_Shdr);
sec = sec->next;
}
{
shdr.sh_name = 1;
shdr.sh_type = SHT_STRTAB;
shdr.sh_flags = 0;
shdr.sh_addr = 0;
shdr.sh_offset = strtbl_offset + data_offset;
shdr.sh_size = strtbl_index;
shdr.sh_link = SHN_UNDEF;
shdr.sh_info = 0;
shdr.sh_addralign = 1;
shdr.sh_entsize = 0;
write(user, offset, &shdr, sizeof shdr);
offset += sizeof(Elf32_Shdr);
}
sec = params->first_section;
while(sec)
{
if(sec->type == EST_LOAD)
write(user, sec->offset, sec->section, sec->size);
sec = sec->next;
}
write(user, strtbl_offset + data_offset, strtbl_content, strtbl_index);
free(strtbl_content);
}
bool elf_read_file(struct elf_params_t *params, elf_read_fn_t read,
elf_printf_fn_t printf, void *user)
{
#define error_printf(...) ({printf(user, true, __VA_ARGS__); return false;})
/* read header */
Elf32_Ehdr ehdr;
if(!read(user, 0, &ehdr, sizeof(ehdr)))
{
printf(user, true, "error reading elf header\n");
return false;
}
/* basic checks */
if(ehdr.e_ident[EI_MAG0] != ELFMAG0 || ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
ehdr.e_ident[EI_MAG2] != ELFMAG2 || ehdr.e_ident[EI_MAG3] != ELFMAG3)
error_printf("invalid elf header\n");
if(ehdr.e_ident[EI_CLASS] != ELFCLASS32)
error_printf("invalid elf class: must be a 32-bit object\n");
if(ehdr.e_ident[EI_DATA] != ELFDATA2LSB)
error_printf("invalid elf data encoding: must be 32-bit lsb\n");
if(ehdr.e_ident[EI_VERSION] != EV_CURRENT)
error_printf("invalid elf version\n");
if(ehdr.e_type != ET_EXEC)
error_printf("invalid elf file: must be an executable file\n");
if(ehdr.e_machine != EM_ARM)
error_printf("invalid elf file: must target an arm machine\n");
if(ehdr.e_ehsize != sizeof(ehdr))
error_printf("invalid elf file: size header mismatch\n");
if(ehdr.e_phnum > 0 && ehdr.e_phentsize != sizeof(Elf32_Phdr))
error_printf("invalid elf file: program header size mismatch\n");
if(ehdr.e_shnum > 0 && ehdr.e_shentsize != sizeof(Elf32_Shdr))
error_printf("invalid elf file: section header size mismatch\n");
elf_set_start_addr(params, ehdr.e_entry);
char *strtab = NULL;
if(ehdr.e_shstrndx != SHN_UNDEF)
{
Elf32_Shdr shstrtab;
if(read(user, ehdr.e_shoff + ehdr.e_shstrndx * ehdr.e_shentsize,
&shstrtab, sizeof(shstrtab)))
{
strtab = xmalloc(shstrtab.sh_size);
if(!read(user, shstrtab.sh_offset, strtab, shstrtab.sh_size))
{
free(strtab);
strtab = NULL;
}
}
}
/* run through sections */
printf(user, false, "ELF file:\n");
for(int i = 1; i < ehdr.e_shnum; i++)
{
uint32_t off = ehdr.e_shoff + i * ehdr.e_shentsize;
Elf32_Shdr shdr;
memset(&shdr, 0, sizeof(shdr));
if(!read(user, off, &shdr, sizeof(shdr)))
error_printf("error reading elf section header");
if(shdr.sh_type == SHT_PROGBITS && shdr.sh_flags & SHF_ALLOC)
{
void *data = xmalloc(shdr.sh_size);
if(!read(user, shdr.sh_offset, data, shdr.sh_size))
error_printf("error read self section data\n");
elf_add_load_section(params, shdr.sh_addr, shdr.sh_size, data);
free(data);
if(strtab)
printf(user, false, "create load segment for %s\n", &strtab[shdr.sh_name]);
}
else if(shdr.sh_type == SHT_NOBITS && shdr.sh_flags & SHF_ALLOC)
{
elf_add_fill_section(params, shdr.sh_addr, shdr.sh_size, 0);
if(strtab)
printf(user, false, "create fill segment for %s\n", &strtab[shdr.sh_name]);
}
else
{
if(strtab)
printf(user, false, "filter out %s\n", &strtab[shdr.sh_name], shdr.sh_type);
}
}
free(strtab);
/* run through segments */
for(int i = 1; i < ehdr.e_phnum; i++)
{
uint32_t off = ehdr.e_phoff + i * ehdr.e_phentsize;
Elf32_Phdr phdr;
memset(&phdr, 0, sizeof(phdr));
if(!read(user, off, &phdr, sizeof(phdr)))
error_printf("error reading elf segment header");
if(phdr.p_type != PT_LOAD)
continue;
struct elf_segment_t *seg = elf_add_segment(params);
seg->vaddr = phdr.p_vaddr;
seg->paddr = phdr.p_paddr;
seg->vsize = phdr.p_memsz;
seg->psize = phdr.p_filesz;
printf(user, false, "create segment [%#x,+%#x[ -> [%#x,+%#x[\n",
seg->vaddr, seg->vsize, seg->paddr, seg->psize);
}
return true;
}
uint32_t elf_translate_virtual_address(struct elf_params_t *params, uint32_t addr)
{
struct elf_segment_t *seg = params->first_segment;
while(seg)
{
if(seg->vaddr <= addr && addr < seg->vaddr + seg->vsize)
return addr - seg->vaddr + seg->paddr;
seg = seg->next;
}
return addr;
}
void elf_translate_addresses(struct elf_params_t *params)
{
struct elf_section_t *sec = params->first_section;
while(sec)
{
sec->addr = elf_translate_virtual_address(params, sec->addr);
sec = sec->next;
}
params->start_addr = elf_translate_virtual_address(params, params->start_addr);
}
bool elf_is_empty(struct elf_params_t *params)
{
return params->first_section == NULL;
}
void elf_set_start_addr(struct elf_params_t *params, uint32_t addr)
{
params->has_start_addr = true;
params->start_addr = addr;
}
bool elf_get_start_addr(struct elf_params_t *params, uint32_t *addr)
{
if(params->has_start_addr && addr != NULL)
*addr = params->start_addr;
return params->has_start_addr;
}
int elf_get_nr_sections(struct elf_params_t *params)
{
int nr = 0;
struct elf_section_t *sec = params->first_section;
while(sec)
{
nr++;
sec = sec->next;
}
return nr;
}
void elf_release(struct elf_params_t *params)
{
struct elf_section_t *sec = params->first_section;
while(sec)
{
struct elf_section_t *next_sec = sec->next;
if(sec->type == EST_LOAD)
free(sec->section);
free(sec);
sec = next_sec;
}
struct elf_segment_t *seg = params->first_segment;
while(seg)
{
struct elf_segment_t *next_seg = seg->next;
free(seg);
seg = next_seg;
}
}
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