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tccelf.c
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/*
* ELF file handling for TCC
*
* Copyright (c) 2001-2004 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "tcc.h"
/* Define this to get some debug output during relocation processing. */
#undef DEBUG_RELOC
/********************************************************/
/* global variables */
/* elf version information */
struct sym_version {
char *lib;
char *version;
int out_index;
int prev_same_lib;
};
#define nb_sym_versions S->nb_sym_versions
#define sym_versions S->sym_versions
#define nb_sym_to_version S->nb_sym_to_version
#define sym_to_version S->sym_to_version
#define dt_verneednum S->dt_verneednum
#define versym_section S->versym_section
#define verneed_section S->verneed_section
/* special flag to indicate that the section should not be linked to the other ones */
#define SHF_PRIVATE 0x80000000
/* section is dynsymtab_section */
#define SHF_DYNSYM 0x40000000
/* ------------------------------------------------------------------------- */
ST_FUNC void tccelf_new(TCCState *S)
{
/* no section zero */
dynarray_add(S, &S->sections, &S->nb_sections, NULL);
/* create standard sections */
text_section = new_section(S, ".text", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR);
data_section = new_section(S, ".data", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
#ifdef TCC_TARGET_PE
rodata_section = new_section(S, ".rdata", SHT_PROGBITS, SHF_ALLOC);
#else
/* create ro data section (make ro after relocation done with GNU_RELRO) */
rodata_section = new_section(S, ".data.ro", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
#endif
bss_section = new_section(S, ".bss", SHT_NOBITS, SHF_ALLOC | SHF_WRITE);
common_section = new_section(S, ".common", SHT_NOBITS, SHF_PRIVATE);
common_section->sh_num = SHN_COMMON;
/* symbols are always generated for linking stage */
symtab_section = new_symtab(S, ".symtab", SHT_SYMTAB, 0,
".strtab",
".hashtab", SHF_PRIVATE);
S->symtab = symtab_section;
/* private symbol table for dynamic symbols */
S->dynsymtab_section = new_symtab(S, ".dynsymtab", SHT_SYMTAB, SHF_PRIVATE|SHF_DYNSYM,
".dynstrtab",
".dynhashtab", SHF_PRIVATE);
get_sym_attr(S, 0, 1);
}
#ifdef CONFIG_TCC_BCHECK
ST_FUNC void tccelf_bounds_new(TCCState *S)
{
/* create bounds sections (make ro after relocation done with GNU_RELRO) */
bounds_section = new_section(S, ".bounds",
SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
lbounds_section = new_section(S, ".lbounds",
SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
}
#endif
ST_FUNC void tccelf_stab_new(TCCState *S)
{
int shf = 0;
#ifdef CONFIG_TCC_BACKTRACE
/* include stab info with standalone backtrace support */
if (S->do_backtrace && S->output_type != TCC_OUTPUT_MEMORY)
shf = SHF_ALLOC | SHF_WRITE; // SHF_WRITE needed for musl/SELINUX
#endif
stab_section = new_section(S, ".stab", SHT_PROGBITS, shf);
stab_section->sh_entsize = sizeof(Stab_Sym);
stab_section->sh_addralign = sizeof ((Stab_Sym*)0)->n_value;
stab_section->link = new_section(S, ".stabstr", SHT_STRTAB, shf);
/* put first entry */
put_stabs(S, "", 0, 0, 0, 0);
}
static void free_section(TCCState *S, Section *s)
{
tcc_free(S, s->data);
}
ST_FUNC void tccelf_delete(TCCState *S)
{
int i;
#ifndef ELF_OBJ_ONLY
/* free symbol versions */
for (i = 0; i < nb_sym_versions; i++) {
tcc_free(S, sym_versions[i].version);
tcc_free(S, sym_versions[i].lib);
}
tcc_free(S, sym_versions);
tcc_free(S, sym_to_version);
#endif
/* free all sections */
for(i = 1; i < S->nb_sections; i++)
free_section(S, S->sections[i]);
dynarray_reset(S, &S->sections, &S->nb_sections);
for(i = 0; i < S->nb_priv_sections; i++)
free_section(S, S->priv_sections[i]);
dynarray_reset(S, &S->priv_sections, &S->nb_priv_sections);
/* free any loaded DLLs */
#ifdef TCC_IS_NATIVE
for ( i = 0; i < S->nb_loaded_dlls; i++) {
DLLReference *ref = S->loaded_dlls[i];
if ( ref->handle )
# ifdef _WIN32
FreeLibrary((HMODULE)ref->handle);
# else
dlclose(ref->handle);
# endif
}
#endif
/* free loaded dlls array */
dynarray_reset(S, &S->loaded_dlls, &S->nb_loaded_dlls);
tcc_free(S, S->sym_attrs);
symtab_section = NULL; /* for tccrun.c:rt_printline() */
}
/* save section data state */
ST_FUNC void tccelf_begin_file(TCCState *S)
{
Section *s; int i;
for (i = 1; i < S->nb_sections; i++) {
s = S->sections[i];
s->sh_offset = s->data_offset;
}
/* disable symbol hashing during compilation */
s = S->symtab, s->reloc = s->hash, s->hash = NULL;
#if defined TCC_TARGET_X86_64 && defined TCC_TARGET_PE
S->uw_sym = 0;
#endif
}
/* At the end of compilation, convert any UNDEF syms to global, and merge
with previously existing symbols */
ST_FUNC void tccelf_end_file(TCCState *S)
{
Section *s = S->symtab;
int first_sym, nb_syms, *tr, i;
first_sym = s->sh_offset / sizeof (ElfSym);
nb_syms = s->data_offset / sizeof (ElfSym) - first_sym;
s->data_offset = s->sh_offset;
s->link->data_offset = s->link->sh_offset;
s->hash = s->reloc, s->reloc = NULL;
tr = tcc_mallocz(S, nb_syms * sizeof *tr);
for (i = 0; i < nb_syms; ++i) {
ElfSym *sym = (ElfSym*)s->data + first_sym + i;
if (sym->st_shndx == SHN_UNDEF
&& ELFW(ST_BIND)(sym->st_info) == STB_LOCAL)
sym->st_info = ELFW(ST_INFO)(STB_GLOBAL, ELFW(ST_TYPE)(sym->st_info));
tr[i] = set_elf_sym(s, sym->st_value, sym->st_size, sym->st_info,
sym->st_other, sym->st_shndx, (char*)s->link->data + sym->st_name);
}
/* now update relocations */
for (i = 1; i < S->nb_sections; i++) {
Section *sr = S->sections[i];
if (sr->sh_type == SHT_RELX && sr->link == s) {
ElfW_Rel *rel = (ElfW_Rel*)(sr->data + sr->sh_offset);
ElfW_Rel *rel_end = (ElfW_Rel*)(sr->data + sr->data_offset);
for (; rel < rel_end; ++rel) {
int n = ELFW(R_SYM)(rel->r_info) - first_sym;
//if (n < 0) tcc_error(S, "internal: invalid symbol index in relocation");
rel->r_info = ELFW(R_INFO)(tr[n], ELFW(R_TYPE)(rel->r_info));
}
}
}
tcc_free(S, tr);
/* record text/data/bss output for -bench info */
for (i = 0; i < 4; ++i) {
s = S->sections[i + 1];
S->total_output[i] += s->data_offset - s->sh_offset;
}
}
ST_FUNC Section *new_section(TCCState *S, const char *name, int sh_type, int sh_flags)
{
Section *sec;
sec = tcc_mallocz(S, sizeof(Section) + strlen(name));
sec->S = S;
strcpy(sec->name, name);
sec->sh_type = sh_type;
sec->sh_flags = sh_flags;
switch(sh_type) {
case SHT_GNU_versym:
sec->sh_addralign = 2;
break;
case SHT_HASH:
case SHT_REL:
case SHT_RELA:
case SHT_DYNSYM:
case SHT_SYMTAB:
case SHT_DYNAMIC:
case SHT_GNU_verneed:
case SHT_GNU_verdef:
sec->sh_addralign = PTR_SIZE;
break;
case SHT_STRTAB:
sec->sh_addralign = 1;
break;
default:
sec->sh_addralign = PTR_SIZE; /* gcc/pcc default alignment */
break;
}
if (sh_flags & SHF_PRIVATE) {
dynarray_add(S, &S->priv_sections, &S->nb_priv_sections, sec);
} else {
sec->sh_num = S->nb_sections;
dynarray_add(S, &S->sections, &S->nb_sections, sec);
}
return sec;
}
ST_FUNC Section *new_symtab(TCCState *S,
const char *symtab_name, int sh_type, int sh_flags,
const char *strtab_name,
const char *hash_name, int hash_sh_flags)
{
Section *symtab, *strtab, *hash;
int *ptr, nb_buckets;
symtab = new_section(S, symtab_name, sh_type, sh_flags);
symtab->sh_entsize = sizeof(ElfW(Sym));
strtab = new_section(S, strtab_name, SHT_STRTAB, sh_flags);
put_elf_str(S, strtab, "");
symtab->link = strtab;
put_elf_sym(S, symtab, 0, 0, 0, 0, 0, NULL);
nb_buckets = 1;
hash = new_section(S, hash_name, SHT_HASH, hash_sh_flags);
hash->sh_entsize = sizeof(int);
symtab->hash = hash;
hash->link = symtab;
ptr = section_ptr_add(S, hash, (2 + nb_buckets + 1) * sizeof(int));
ptr[0] = nb_buckets;
ptr[1] = 1;
memset(ptr + 2, 0, (nb_buckets + 1) * sizeof(int));
return symtab;
}
/* realloc section and set its content to zero */
ST_FUNC void section_realloc(TCCState *S, Section *sec, unsigned long new_size)
{
unsigned long size;
unsigned char *data;
size = sec->data_allocated;
if (size == 0)
size = 1;
while (size < new_size)
size = size * 2;
data = tcc_realloc(S, sec->data, size);
memset(data + sec->data_allocated, 0, size - sec->data_allocated);
sec->data = data;
sec->data_allocated = size;
}
/* reserve at least 'size' bytes aligned per 'align' in section
'sec' from current offset, and return the aligned offset */
ST_FUNC size_t section_add(TCCState *S, Section *sec, addr_t size, int align)
{
size_t offset, offset1;
offset = (sec->data_offset + align - 1) & -align;
offset1 = offset + size;
if (sec->sh_type != SHT_NOBITS && offset1 > sec->data_allocated)
section_realloc(S, sec, offset1);
sec->data_offset = offset1;
if (align > sec->sh_addralign)
sec->sh_addralign = align;
return offset;
}
/* reserve at least 'size' bytes in section 'sec' from
sec->data_offset. */
ST_FUNC void *section_ptr_add(TCCState *S, Section *sec, addr_t size)
{
size_t offset = section_add(S, sec, size, 1);
return sec->data + offset;
}
#ifndef ELF_OBJ_ONLY
/* reserve at least 'size' bytes from section start */
static void section_reserve(TCCState *S, Section *sec, unsigned long size)
{
if (size > sec->data_allocated)
section_realloc(S, sec, size);
if (size > sec->data_offset)
sec->data_offset = size;
}
#endif
static Section *find_section_create (TCCState *S, const char *name, int create)
{
Section *sec;
int i;
for(i = 1; i < S->nb_sections; i++) {
sec = S->sections[i];
if (!strcmp(name, sec->name))
return sec;
}
/* sections are created as PROGBITS */
return create ? new_section(S, name, SHT_PROGBITS, SHF_ALLOC) : NULL;
}
/* return a reference to a section, and create it if it does not
exists */
ST_FUNC Section *find_section(TCCState *S, const char *name)
{
return find_section_create (S, name, 1);
}
/* ------------------------------------------------------------------------- */
ST_FUNC int put_elf_str(TCCState *S, Section *s, const char *sym)
{
int offset, len;
char *ptr;
len = strlen(sym) + 1;
offset = s->data_offset;
ptr = section_ptr_add(S, s, len);
memmove(ptr, sym, len);
return offset;
}
/* elf symbol hashing function */
static unsigned long elf_hash(const unsigned char *name)
{
unsigned long h = 0, g;
while (*name) {
h = (h << 4) + *name++;
g = h & 0xf0000000;
if (g)
h ^= g >> 24;
h &= ~g;
}
return h;
}
/* rebuild hash table of section s */
/* NOTE: we do factorize the hash table code to go faster */
static void rebuild_hash(TCCState *S, Section *s, unsigned int nb_buckets)
{
ElfW(Sym) *sym;
int *ptr, *hash, nb_syms, sym_index, h;
unsigned char *strtab;
strtab = s->link->data;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
if (!nb_buckets)
nb_buckets = ((int*)s->hash->data)[0];
s->hash->data_offset = 0;
ptr = section_ptr_add(S, s->hash, (2 + nb_buckets + nb_syms) * sizeof(int));
ptr[0] = nb_buckets;
ptr[1] = nb_syms;
ptr += 2;
hash = ptr;
memset(hash, 0, (nb_buckets + 1) * sizeof(int));
ptr += nb_buckets + 1;
sym = (ElfW(Sym) *)s->data + 1;
for(sym_index = 1; sym_index < nb_syms; sym_index++) {
if (ELFW(ST_BIND)(sym->st_info) != STB_LOCAL) {
h = elf_hash(strtab + sym->st_name) % nb_buckets;
*ptr = hash[h];
hash[h] = sym_index;
} else {
*ptr = 0;
}
ptr++;
sym++;
}
}
/* return the symbol number */
ST_FUNC int put_elf_sym(TCCState *S, Section *s, addr_t value, unsigned long size,
int info, int other, int shndx, const char *name)
{
int name_offset, sym_index;
int nbuckets, h;
ElfW(Sym) *sym;
Section *hs;
sym = section_ptr_add(S, s, sizeof(ElfW(Sym)));
if (name && name[0])
name_offset = put_elf_str(S, s->link, name);
else
name_offset = 0;
/* XXX: endianness */
sym->st_name = name_offset;
sym->st_value = value;
sym->st_size = size;
sym->st_info = info;
sym->st_other = other;
sym->st_shndx = shndx;
sym_index = sym - (ElfW(Sym) *)s->data;
hs = s->hash;
if (hs) {
int *ptr, *base;
ptr = section_ptr_add(S, hs, sizeof(int));
base = (int *)hs->data;
/* only add global or weak symbols. */
if (ELFW(ST_BIND)(info) != STB_LOCAL) {
/* add another hashing entry */
nbuckets = base[0];
h = elf_hash((unsigned char *)s->link->data + name_offset) % nbuckets;
*ptr = base[2 + h];
base[2 + h] = sym_index;
base[1]++;
/* we resize the hash table */
hs->nb_hashed_syms++;
if (hs->nb_hashed_syms > 2 * nbuckets) {
rebuild_hash(S, s, 2 * nbuckets);
}
} else {
*ptr = 0;
base[1]++;
}
}
return sym_index;
}
ST_FUNC int find_elf_sym(Section *s, const char *name)
{
ElfW(Sym) *sym;
Section *hs;
int nbuckets, sym_index, h;
const char *name1;
hs = s->hash;
if (!hs)
return 0;
nbuckets = ((int *)hs->data)[0];
h = elf_hash((unsigned char *) name) % nbuckets;
sym_index = ((int *)hs->data)[2 + h];
while (sym_index != 0) {
sym = &((ElfW(Sym) *)s->data)[sym_index];
name1 = (char *) s->link->data + sym->st_name;
if (!strcmp(name, name1))
return sym_index;
sym_index = ((int *)hs->data)[2 + nbuckets + sym_index];
}
return 0;
}
/* return elf symbol value, signal error if 'err' is nonzero, decorate
name if FORC */
ST_FUNC addr_t get_sym_addr(TCCState *S, const char *name, int err, int forc)
{
int sym_index;
ElfW(Sym) *sym;
char buf[256];
if (forc && S->leading_underscore
#ifdef TCC_TARGET_PE
/* win32-32bit stdcall symbols always have _ already */
&& !strchr(name, '@')
#endif
) {
buf[0] = '_';
pstrcpy(buf + 1, sizeof(buf) - 1, name);
name = buf;
}
sym_index = find_elf_sym(S->symtab, name);
sym = &((ElfW(Sym) *)S->symtab->data)[sym_index];
if (!sym_index || sym->st_shndx == SHN_UNDEF) {
if (err)
tcc_error(S, "%s not defined", name);
return (addr_t)-1;
}
return sym->st_value;
}
/* return elf symbol value */
LIBTCCAPI void *tcc_get_symbol(TCCState *S, const char *name)
{
addr_t addr = get_sym_addr(S, name, 0, 1);
return addr == -1 ? NULL : (void*)(uintptr_t)addr;
}
/* list elf symbol names and values */
ST_FUNC void list_elf_symbols(TCCState *S, void *ctx,
void (*symbol_cb)(void *ctx, const char *name, const void *val))
{
ElfW(Sym) *sym;
Section *symtab;
int sym_index, end_sym;
const char *name;
unsigned char sym_vis, sym_bind;
symtab = S->symtab;
end_sym = symtab->data_offset / sizeof (ElfSym);
for (sym_index = 0; sym_index < end_sym; ++sym_index) {
sym = &((ElfW(Sym) *)symtab->data)[sym_index];
if (sym->st_value) {
name = (char *) symtab->link->data + sym->st_name;
sym_bind = ELFW(ST_BIND)(sym->st_info);
sym_vis = ELFW(ST_VISIBILITY)(sym->st_other);
if (sym_bind == STB_GLOBAL && sym_vis == STV_DEFAULT)
symbol_cb(ctx, name, (void*)(uintptr_t)sym->st_value);
}
}
}
/* list elf symbol names and values */
LIBTCCAPI void tcc_list_symbols(TCCState *S, void *ctx,
void (*symbol_cb)(void *ctx, const char *name, const void *val))
{
list_elf_symbols(S, ctx, symbol_cb);
}
#ifndef ELF_OBJ_ONLY
static void
version_add (TCCState *S)
{
int i;
ElfW(Sym) *sym;
ElfW(Verneed) *vn = NULL;
Section *symtab;
int sym_index, end_sym, nb_versions = 2, nb_entries = 0;
ElfW(Half) *versym;
const char *name;
if (0 == nb_sym_versions)
return;
versym_section = new_section(S, ".gnu.version", SHT_GNU_versym, SHF_ALLOC);
versym_section->sh_entsize = sizeof(ElfW(Half));
versym_section->link = S->dynsym;
/* add needed symbols */
symtab = S->dynsym;
end_sym = symtab->data_offset / sizeof (ElfSym);
versym = section_ptr_add(S, versym_section, end_sym * sizeof(ElfW(Half)));
for (sym_index = 0; sym_index < end_sym; ++sym_index) {
int dllindex, verndx;
sym = &((ElfW(Sym) *)symtab->data)[sym_index];
name = (char *) symtab->link->data + sym->st_name;
dllindex = find_elf_sym(S->dynsymtab_section, name);
verndx = (dllindex && dllindex < nb_sym_to_version)
? sym_to_version[dllindex] : -1;
if (verndx >= 0) {
if (!sym_versions[verndx].out_index)
sym_versions[verndx].out_index = nb_versions++;
versym[sym_index] = sym_versions[verndx].out_index;
} else
versym[sym_index] = 0;
}
/* generate verneed section, but not when it will be empty. Some
dynamic linkers look at their contents even when DTVERNEEDNUM and
section size is zero. */
if (nb_versions > 2) {
verneed_section = new_section(S, ".gnu.version_r",
SHT_GNU_verneed, SHF_ALLOC);
verneed_section->link = S->dynsym->link;
for (i = nb_sym_versions; i-- > 0;) {
struct sym_version *sv = &sym_versions[i];
int n_same_libs = 0, prev;
size_t vnofs;
ElfW(Vernaux) *vna = 0;
if (sv->out_index < 1)
continue;
vnofs = section_add(S, verneed_section, sizeof(*vn), 1);
vn = (ElfW(Verneed)*)(verneed_section->data + vnofs);
vn->vn_version = 1;
vn->vn_file = put_elf_str(S, verneed_section->link, sv->lib);
vn->vn_aux = sizeof (*vn);
do {
prev = sv->prev_same_lib;
if (sv->out_index > 0) {
vna = section_ptr_add(S, verneed_section, sizeof(*vna));
vna->vna_hash = elf_hash ((const unsigned char *)sv->version);
vna->vna_flags = 0;
vna->vna_other = sv->out_index;
sv->out_index = -2;
vna->vna_name = put_elf_str(S, verneed_section->link, sv->version);
vna->vna_next = sizeof (*vna);
n_same_libs++;
}
if (prev >= 0)
sv = &sym_versions[prev];
} while(prev >= 0);
vna->vna_next = 0;
vn = (ElfW(Verneed)*)(verneed_section->data + vnofs);
vn->vn_cnt = n_same_libs;
vn->vn_next = sizeof(*vn) + n_same_libs * sizeof(*vna);
nb_entries++;
}
if (vn)
vn->vn_next = 0;
verneed_section->sh_info = nb_entries;
}
dt_verneednum = nb_entries;
}
#endif
/* add an elf symbol : check if it is already defined and patch
it. Return symbol index. NOTE that sh_num can be SHN_UNDEF. */
ST_FUNC int set_elf_sym(Section *s, addr_t value, unsigned long size,
int info, int other, int shndx, const char *name)
{
TCCState *S = s->S;
ElfW(Sym) *esym;
int sym_bind, sym_index, sym_type, esym_bind;
unsigned char sym_vis, esym_vis, new_vis;
sym_bind = ELFW(ST_BIND)(info);
sym_type = ELFW(ST_TYPE)(info);
sym_vis = ELFW(ST_VISIBILITY)(other);
if (sym_bind != STB_LOCAL) {
/* we search global or weak symbols */
sym_index = find_elf_sym(s, name);
if (!sym_index)
goto do_def;
esym = &((ElfW(Sym) *)s->data)[sym_index];
if (esym->st_value == value && esym->st_size == size && esym->st_info == info
&& esym->st_other == other && esym->st_shndx == shndx)
return sym_index;
if (esym->st_shndx != SHN_UNDEF) {
esym_bind = ELFW(ST_BIND)(esym->st_info);
/* propagate the most constraining visibility */
/* STV_DEFAULT(0)<STV_PROTECTED(3)<STV_HIDDEN(2)<STV_INTERNAL(1) */
esym_vis = ELFW(ST_VISIBILITY)(esym->st_other);
if (esym_vis == STV_DEFAULT) {
new_vis = sym_vis;
} else if (sym_vis == STV_DEFAULT) {
new_vis = esym_vis;
} else {
new_vis = (esym_vis < sym_vis) ? esym_vis : sym_vis;
}
esym->st_other = (esym->st_other & ~ELFW(ST_VISIBILITY)(-1))
| new_vis;
other = esym->st_other; /* in case we have to patch esym */
if (shndx == SHN_UNDEF) {
/* ignore adding of undefined symbol if the
corresponding symbol is already defined */
} else if (sym_bind == STB_GLOBAL && esym_bind == STB_WEAK) {
/* global overrides weak, so patch */
goto do_patch;
} else if (sym_bind == STB_WEAK && esym_bind == STB_GLOBAL) {
/* weak is ignored if already global */
} else if (sym_bind == STB_WEAK && esym_bind == STB_WEAK) {
/* keep first-found weak definition, ignore subsequents */
} else if (sym_vis == STV_HIDDEN || sym_vis == STV_INTERNAL) {
/* ignore hidden symbols after */
} else if ((esym->st_shndx == SHN_COMMON
|| esym->st_shndx == bss_section->sh_num)
&& (shndx < SHN_LORESERVE
&& shndx != bss_section->sh_num)) {
/* data symbol gets precedence over common/bss */
goto do_patch;
} else if (shndx == SHN_COMMON || shndx == bss_section->sh_num) {
/* data symbol keeps precedence over common/bss */
} else if (s->sh_flags & SHF_DYNSYM) {
/* we accept that two DLL define the same symbol */
} else if (esym->st_other & ST_ASM_SET) {
/* If the existing symbol came from an asm .set
we can override. */
goto do_patch;
} else {
#if 0
printf("new_bind=%x new_shndx=%x new_vis=%x old_bind=%x old_shndx=%x old_vis=%x\n",
sym_bind, shndx, new_vis, esym_bind, esym->st_shndx, esym_vis);
#endif
tcc_error_noabort(S, "'%s' defined twice", name);
}
} else {
do_patch:
esym->st_info = ELFW(ST_INFO)(sym_bind, sym_type);
esym->st_shndx = shndx;
S->new_undef_sym = 1;
esym->st_value = value;
esym->st_size = size;
esym->st_other = other;
}
} else {
do_def:
sym_index = put_elf_sym(S, s, value, size,
ELFW(ST_INFO)(sym_bind, sym_type), other,
shndx, name);
}
return sym_index;
}
/* put relocation */
ST_FUNC void put_elf_reloca(Section *symtab, Section *s, unsigned long offset,
int type, int symbol, addr_t addend)
{
TCCState *S = s->S;
char buf[256];
Section *sr;
ElfW_Rel *rel;
sr = s->reloc;
if (!sr) {
/* if no relocation section, create it */
snprintf(buf, sizeof(buf), REL_SECTION_FMT, s->name);
/* if the symtab is allocated, then we consider the relocation
are also */
sr = new_section(s->S, buf, SHT_RELX, symtab->sh_flags);
sr->sh_entsize = sizeof(ElfW_Rel);
sr->link = symtab;
sr->sh_info = s->sh_num;
s->reloc = sr;
}
rel = section_ptr_add(S, sr, sizeof(ElfW_Rel));
rel->r_offset = offset;
rel->r_info = ELFW(R_INFO)(symbol, type);
#if SHT_RELX == SHT_RELA
rel->r_addend = addend;
#endif
if (SHT_RELX != SHT_RELA && addend)
tcc_error(S, "non-zero addend on REL architecture");
}
ST_FUNC void put_elf_reloc(Section *symtab, Section *s, unsigned long offset,
int type, int symbol)
{
put_elf_reloca(symtab, s, offset, type, symbol, 0);
}
/* put stab debug information */
ST_FUNC void put_stabs(TCCState *S, const char *str, int type, int other, int desc,
unsigned long value)
{
Stab_Sym *sym;
unsigned offset;
if (type == N_SLINE
&& (offset = stab_section->data_offset)
&& (sym = (Stab_Sym*)(stab_section->data + offset) - 1)
&& sym->n_type == type
&& sym->n_value == value) {
/* just update line_number in previous entry */
sym->n_desc = desc;
return;
}
sym = section_ptr_add(S, stab_section, sizeof(Stab_Sym));
if (str) {
sym->n_strx = put_elf_str(S, stab_section->link, str);
} else {
sym->n_strx = 0;
}
sym->n_type = type;
sym->n_other = other;
sym->n_desc = desc;
sym->n_value = value;
}
ST_FUNC void put_stabs_r(TCCState *S, const char *str, int type, int other, int desc,
unsigned long value, Section *sec, int sym_index)
{
put_elf_reloc(symtab_section, stab_section,
stab_section->data_offset + 8,
sizeof ((Stab_Sym*)0)->n_value == PTR_SIZE ? R_DATA_PTR : R_DATA_32,
sym_index);
put_stabs(S, str, type, other, desc, value);
}
ST_FUNC void put_stabn(TCCState *S, int type, int other, int desc, int value)
{
put_stabs(S, NULL, type, other, desc, value);
}
ST_FUNC struct sym_attr *get_sym_attr(TCCState *S, int index, int alloc)
{
int n;
struct sym_attr *tab;
if (index >= S->nb_sym_attrs) {
if (!alloc)
return S->sym_attrs;
/* find immediately bigger power of 2 and reallocate array */
n = 1;
while (index >= n)
n *= 2;
tab = tcc_realloc(S, S->sym_attrs, n * sizeof(*S->sym_attrs));
S->sym_attrs = tab;
memset(S->sym_attrs + S->nb_sym_attrs, 0,
(n - S->nb_sym_attrs) * sizeof(*S->sym_attrs));
S->nb_sym_attrs = n;
}
return &S->sym_attrs[index];
}
/* In an ELF file symbol table, the local symbols must appear below
the global and weak ones. Since TCC cannot sort it while generating
the code, we must do it after. All the relocation tables are also
modified to take into account the symbol table sorting */
static void sort_syms(TCCState *S, Section *s)
{
int *old_to_new_syms;
ElfW(Sym) *new_syms;
int nb_syms, i;
ElfW(Sym) *p, *q;
ElfW_Rel *rel;
Section *sr;
int type, sym_index;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
new_syms = tcc_malloc(S, nb_syms * sizeof(ElfW(Sym)));
old_to_new_syms = tcc_malloc(S, nb_syms * sizeof(int));
/* first pass for local symbols */
p = (ElfW(Sym) *)s->data;
q = new_syms;
for(i = 0; i < nb_syms; i++) {
if (ELFW(ST_BIND)(p->st_info) == STB_LOCAL) {
old_to_new_syms[i] = q - new_syms;
*q++ = *p;
}
p++;
}
/* save the number of local symbols in section header */
if( s->sh_size ) /* this 'if' makes IDA happy */
s->sh_info = q - new_syms;
/* then second pass for non local symbols */
p = (ElfW(Sym) *)s->data;
for(i = 0; i < nb_syms; i++) {
if (ELFW(ST_BIND)(p->st_info) != STB_LOCAL) {
old_to_new_syms[i] = q - new_syms;
*q++ = *p;
}
p++;
}
/* we copy the new symbols to the old */
memcpy(s->data, new_syms, nb_syms * sizeof(ElfW(Sym)));
tcc_free(S, new_syms);
/* now we modify all the relocations */
for(i = 1; i < S->nb_sections; i++) {
sr = S->sections[i];
if (sr->sh_type == SHT_RELX && sr->link == s) {
for_each_elem(sr, 0, rel, ElfW_Rel) {
sym_index = ELFW(R_SYM)(rel->r_info);
type = ELFW(R_TYPE)(rel->r_info);
sym_index = old_to_new_syms[sym_index];
rel->r_info = ELFW(R_INFO)(sym_index, type);
}
}
}
tcc_free(S, old_to_new_syms);
}
/* relocate symbol table, resolve undefined symbols if do_resolve is
true and output error if undefined symbol. */
ST_FUNC void relocate_syms(TCCState *S, Section *symtab, int do_resolve)
{
ElfW(Sym) *sym;
int sym_bind, sh_num;
const char *name;
for_each_elem(symtab, 1, sym, ElfW(Sym)) {
sh_num = sym->st_shndx;
if (sh_num == SHN_UNDEF) {
name = (char *) S->symtab->link->data + sym->st_name;
/* Use ld.so to resolve symbol for us (for tcc -run) */
if (do_resolve) {
#if defined TCC_IS_NATIVE && !defined TCC_TARGET_PE
/* dlsym() needs the undecorated name. */
void *addr = dlsym(RTLD_DEFAULT, &name[S->leading_underscore]);
#if TARGETOS_OpenBSD || TARGETOS_FreeBSD || TARGETOS_NetBSD
if (addr == NULL) {
int i;
for (i = 0; i < S->nb_loaded_dlls; i++)
if ((addr = dlsym(S->loaded_dlls[i]->handle, name)))
break;
}
#endif
if (addr) {
sym->st_value = (addr_t) addr;
#ifdef DEBUG_RELOC
printf ("relocate_sym: %s -> 0x%lx\n", name, sym->st_value);
#endif
goto found;
}
#endif
/* if dynamic symbol exist, it will be used in relocate_section */
} else if (S->dynsym && find_elf_sym(S->dynsym, name))
goto found;
/* XXX: _fp_hw seems to be part of the ABI, so we ignore
it */
if (!strcmp(name, "_fp_hw"))
goto found;
/* only weak symbols are accepted to be undefined. Their
value is zero */
sym_bind = ELFW(ST_BIND)(sym->st_info);
if (sym_bind == STB_WEAK)
sym->st_value = 0;
else
tcc_error_noabort(S, "undefined symbol '%s'", name);
} else if (sh_num < SHN_LORESERVE) {
/* add section base */
sym->st_value += S->sections[sym->st_shndx]->sh_addr;
}
found: ;
}
}
/* relocate a given section (CPU dependent) by applying the relocations
in the associated relocation section */
static void relocate_section(TCCState *S, Section *s, Section *sr)
{
ElfW_Rel *rel;
ElfW(Sym) *sym;
int type, sym_index;
unsigned char *ptr;
addr_t tgt, addr;
qrel = (ElfW_Rel *)sr->data;
for_each_elem(sr, 0, rel, ElfW_Rel) {
ptr = s->data + rel->r_offset;
sym_index = ELFW(R_SYM)(rel->r_info);
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
type = ELFW(R_TYPE)(rel->r_info);
tgt = sym->st_value;
#if SHT_RELX == SHT_RELA
tgt += rel->r_addend;
#endif
addr = s->sh_addr + rel->r_offset;
relocate(S, rel, type, ptr, addr, tgt);
}
#ifndef ELF_OBJ_ONLY
/* if the relocation is allocated, we change its symbol table */
if (sr->sh_flags & SHF_ALLOC) {
sr->link = S->dynsym;
if (S->output_type == TCC_OUTPUT_DLL) {
size_t r = (uint8_t*)qrel - sr->data;
if (sizeof ((Stab_Sym*)0)->n_value < PTR_SIZE
&& 0 == strcmp(s->name, ".stab"))
r = 0; /* cannot apply 64bit relocation to 32bit value */
sr->data_offset = sr->sh_size = r;
}
}
#endif
}
/* relocate all sections */
ST_FUNC void relocate_sections(TCCState *S)
{
int i;
Section *s, *sr;
for (i = 1; i < S->nb_sections; ++i) {
sr = S->sections[i];
if (sr->sh_type != SHT_RELX)
continue;
s = S->sections[sr->sh_info];