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tccelf.c
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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
*/
#ifdef TCC_TARGET_X86_64
#define ElfW_Rel ElfW(Rela)
#define SHT_RELX SHT_RELA
#define REL_SECTION_FMT ".rela%s"
/* x86-64 requires PLT for DLLs */
#define TCC_OUTPUT_DLL_WITH_PLT
#else
#define ElfW_Rel ElfW(Rel)
#define SHT_RELX SHT_REL
#define REL_SECTION_FMT ".rel%s"
#endif
/* XXX: DLL with PLT would only work with x86-64 for now */
//#define TCC_OUTPUT_DLL_WITH_PLT
static int put_elf_str(Section *s, const char *sym)
{
int offset, len;
char *ptr;
len = strlen(sym) + 1;
offset = s->data_offset;
ptr = section_ptr_add(s, len);
memcpy(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(Section *s, unsigned int nb_buckets)
{
ElfW(Sym) *sym;
int *ptr, *hash, nb_syms, sym_index, h;
char *strtab;
strtab = s->link->data;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
s->hash->data_offset = 0;
ptr = section_ptr_add(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 */
static int put_elf_sym(Section *s,
unsigned long 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, sizeof(ElfW(Sym)));
if (name)
name_offset = put_elf_str(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(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(name) % 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, 2 * nbuckets);
}
} else {
*ptr = 0;
base[1]++;
}
}
return sym_index;
}
/* find global ELF symbol 'name' and return its index. Return 0 if not
found. */
static 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(name) % nbuckets;
sym_index = ((int *)hs->data)[2 + h];
while (sym_index != 0) {
sym = &((ElfW(Sym) *)s->data)[sym_index];
name1 = 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 or error */
void *tcc_get_symbol(TCCState *s, const char *name)
{
int sym_index;
ElfW(Sym) *sym;
sym_index = find_elf_sym(symtab_section, name);
if (!sym_index)
return NULL;
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
return (void*)(long)sym->st_value;
}
void *tcc_get_symbol_err(TCCState *s, const char *name)
{
void *sym;
sym = tcc_get_symbol(s, name);
if (!sym)
error("%s not defined", name);
return sym;
}
/* add an elf symbol : check if it is already defined and patch
it. Return symbol index. NOTE that sh_num can be SHN_UNDEF. */
static int add_elf_sym(Section *s, unsigned long value, unsigned long size,
int info, int other, int sh_num, const char *name)
{
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_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 (sh_num == 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_vis == STV_HIDDEN || sym_vis == STV_INTERNAL) {
/* ignore hidden symbols after */
} else if (esym->st_shndx == SHN_COMMON && sh_num < SHN_LORESERVE) {
/* gr: Happens with 'tcc ... -static tcctest.c' on e.g. Ubuntu 6.01
No idea if this is the correct solution ... */
goto do_patch;
} else if (s == tcc_state->dynsymtab_section) {
/* we accept that two DLL define the same symbol */
} else {
#if 1
printf("new_bind=%x new_shndx=%x new_vis=%x old_bind=%x old_shndx=%x old_vis=%x\n",
sym_bind, sh_num, new_vis, esym_bind, esym->st_shndx, esym_vis);
#endif
error_noabort("'%s' defined twice", name);
}
} else {
do_patch:
esym->st_info = ELFW(ST_INFO)(sym_bind, sym_type);
esym->st_shndx = sh_num;
esym->st_value = value;
esym->st_size = size;
esym->st_other = other;
}
} else {
do_def:
sym_index = put_elf_sym(s, value, size,
ELFW(ST_INFO)(sym_bind, sym_type), other,
sh_num, name);
}
return sym_index;
}
/* put relocation */
static void put_elf_reloc(Section *symtab, Section *s, unsigned long offset,
int type, int symbol)
{
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(tcc_state, 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(sr, sizeof(ElfW_Rel));
rel->r_offset = offset;
rel->r_info = ELFW(R_INFO)(symbol, type);
#ifdef TCC_TARGET_X86_64
rel->r_addend = 0;
#endif
}
/* put stab debug information */
typedef struct {
unsigned int n_strx; /* index into string table of name */
unsigned char n_type; /* type of symbol */
unsigned char n_other; /* misc info (usually empty) */
unsigned short n_desc; /* description field */
unsigned int n_value; /* value of symbol */
} Stab_Sym;
static void put_stabs(const char *str, int type, int other, int desc,
unsigned long value)
{
Stab_Sym *sym;
sym = section_ptr_add(stab_section, sizeof(Stab_Sym));
if (str) {
sym->n_strx = put_elf_str(stabstr_section, str);
} else {
sym->n_strx = 0;
}
sym->n_type = type;
sym->n_other = other;
sym->n_desc = desc;
sym->n_value = value;
}
static void put_stabs_r(const char *str, int type, int other, int desc,
unsigned long value, Section *sec, int sym_index)
{
put_stabs(str, type, other, desc, value);
put_elf_reloc(symtab_section, stab_section,
stab_section->data_offset - sizeof(unsigned int),
R_DATA_32, sym_index);
}
static void put_stabn(int type, int other, int desc, int value)
{
put_stabs(NULL, type, other, desc, value);
}
static void put_stabd(int type, int other, int desc)
{
put_stabs(NULL, type, other, desc, 0);
}
/* 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 *s1, Section *s)
{
int *old_to_new_syms;
ElfW(Sym) *new_syms;
int nb_syms, i;
ElfW(Sym) *p, *q;
ElfW_Rel *rel, *rel_end;
Section *sr;
int type, sym_index;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
new_syms = tcc_malloc(nb_syms * sizeof(ElfW(Sym)));
old_to_new_syms = tcc_malloc(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 */
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(new_syms);
/* now we modify all the relocations */
for(i = 1; i < s1->nb_sections; i++) {
sr = s1->sections[i];
if (sr->sh_type == SHT_RELX && sr->link == s) {
rel_end = (ElfW_Rel *)(sr->data + sr->data_offset);
for(rel = (ElfW_Rel *)sr->data;
rel < rel_end;
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(old_to_new_syms);
}
/* relocate common symbols in the .bss section */
static void relocate_common_syms(void)
{
ElfW(Sym) *sym, *sym_end;
unsigned long offset, align;
sym_end = (ElfW(Sym) *)(symtab_section->data + symtab_section->data_offset);
for(sym = (ElfW(Sym) *)symtab_section->data + 1;
sym < sym_end;
sym++) {
if (sym->st_shndx == SHN_COMMON) {
/* align symbol */
align = sym->st_value;
offset = bss_section->data_offset;
offset = (offset + align - 1) & -align;
sym->st_value = offset;
sym->st_shndx = bss_section->sh_num;
offset += sym->st_size;
bss_section->data_offset = offset;
}
}
}
/* relocate symbol table, resolve undefined symbols if do_resolve is
true and output error if undefined symbol. */
static void relocate_syms(TCCState *s1, int do_resolve)
{
ElfW(Sym) *sym, *esym, *sym_end;
int sym_bind, sh_num, sym_index;
const char *name;
unsigned long addr;
sym_end = (ElfW(Sym) *)(symtab_section->data + symtab_section->data_offset);
for(sym = (ElfW(Sym) *)symtab_section->data + 1;
sym < sym_end;
sym++) {
sh_num = sym->st_shndx;
if (sh_num == SHN_UNDEF) {
name = strtab_section->data + sym->st_name;
if (do_resolve) {
name = symtab_section->link->data + sym->st_name;
addr = (unsigned long)resolve_sym(s1, name, ELFW(ST_TYPE)(sym->st_info));
if (addr) {
sym->st_value = addr;
goto found;
}
} else if (s1->dynsym) {
/* if dynamic symbol exist, then use it */
sym_index = find_elf_sym(s1->dynsym, name);
if (sym_index) {
esym = &((ElfW(Sym) *)s1->dynsym->data)[sym_index];
sym->st_value = esym->st_value;
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 {
error_noabort("undefined symbol '%s'", name);
}
} else if (sh_num < SHN_LORESERVE) {
/* add section base */
sym->st_value += s1->sections[sym->st_shndx]->sh_addr;
}
found: ;
}
}
#ifdef TCC_TARGET_X86_64
#define JMP_TABLE_ENTRY_SIZE 14
static unsigned long add_jmp_table(TCCState *s1, unsigned long val)
{
char *p = s1->runtime_plt_and_got + s1->runtime_plt_and_got_offset;
s1->runtime_plt_and_got_offset += JMP_TABLE_ENTRY_SIZE;
/* jmp *0x0(%rip) */
p[0] = 0xff;
p[1] = 0x25;
*(int *)(p + 2) = 0;
*(unsigned long *)(p + 6) = val;
return (unsigned long)p;
}
static unsigned long add_got_table(TCCState *s1, unsigned long val)
{
unsigned long *p =(unsigned long *)(s1->runtime_plt_and_got +
s1->runtime_plt_and_got_offset);
s1->runtime_plt_and_got_offset += sizeof(void *);
*p = val;
return (unsigned long)p;
}
#endif
/* relocate a given section (CPU dependent) */
static void relocate_section(TCCState *s1, Section *s)
{
Section *sr;
ElfW_Rel *rel, *rel_end, *qrel;
ElfW(Sym) *sym;
int type, sym_index;
unsigned char *ptr;
unsigned long val, addr;
#if defined TCC_TARGET_I386 || defined TCC_TARGET_X86_64
int esym_index;
#endif
sr = s->reloc;
rel_end = (ElfW_Rel *)(sr->data + sr->data_offset);
qrel = (ElfW_Rel *)sr->data;
for(rel = qrel;
rel < rel_end;
rel++) {
ptr = s->data + rel->r_offset;
sym_index = ELFW(R_SYM)(rel->r_info);
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
val = sym->st_value;
#ifdef TCC_TARGET_X86_64
/* XXX: not tested */
val += rel->r_addend;
#endif
type = ELFW(R_TYPE)(rel->r_info);
addr = s->sh_addr + rel->r_offset;
/* CPU specific */
switch(type) {
#if defined(TCC_TARGET_I386)
case R_386_32:
if (s1->output_type == TCC_OUTPUT_DLL) {
esym_index = s1->symtab_to_dynsym[sym_index];
qrel->r_offset = rel->r_offset;
if (esym_index) {
qrel->r_info = ELFW(R_INFO)(esym_index, R_386_32);
qrel++;
break;
} else {
qrel->r_info = ELFW(R_INFO)(0, R_386_RELATIVE);
qrel++;
}
}
*(int *)ptr += val;
break;
case R_386_PC32:
if (s1->output_type == TCC_OUTPUT_DLL) {
/* DLL relocation */
esym_index = s1->symtab_to_dynsym[sym_index];
if (esym_index) {
qrel->r_offset = rel->r_offset;
qrel->r_info = ELFW(R_INFO)(esym_index, R_386_PC32);
qrel++;
break;
}
}
*(int *)ptr += val - addr;
break;
case R_386_PLT32:
*(int *)ptr += val - addr;
break;
case R_386_GLOB_DAT:
case R_386_JMP_SLOT:
*(int *)ptr = val;
break;
case R_386_GOTPC:
*(int *)ptr += s1->got->sh_addr - addr;
break;
case R_386_GOTOFF:
*(int *)ptr += val - s1->got->sh_addr;
break;
case R_386_GOT32:
/* we load the got offset */
*(int *)ptr += s1->got_offsets[sym_index];
break;
#elif defined(TCC_TARGET_ARM)
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
case R_ARM_PLT32:
{
int x;
x = (*(int *)ptr)&0xffffff;
(*(int *)ptr) &= 0xff000000;
if (x & 0x800000)
x -= 0x1000000;
x *= 4;
x += val - addr;
if((x & 3) != 0 || x >= 0x4000000 || x < -0x4000000)
error("can't relocate value at %x",addr);
x >>= 2;
x &= 0xffffff;
(*(int *)ptr) |= x;
}
break;
case R_ARM_PREL31:
{
int x;
x = (*(int *)ptr) & 0x7fffffff;
(*(int *)ptr) &= 0x80000000;
x = (x * 2) / 2;
x += val - addr;
if((x^(x>>1))&0x40000000)
error("can't relocate value at %x",addr);
(*(int *)ptr) |= x & 0x7fffffff;
}
case R_ARM_ABS32:
*(int *)ptr += val;
break;
case R_ARM_BASE_PREL:
*(int *)ptr += s1->got->sh_addr - addr;
break;
case R_ARM_GOTOFF32:
*(int *)ptr += val - s1->got->sh_addr;
break;
case R_ARM_GOT_BREL:
/* we load the got offset */
*(int *)ptr += s1->got_offsets[sym_index];
break;
case R_ARM_COPY:
break;
default:
fprintf(stderr,"FIXME: handle reloc type %x at %lx [%.8x] to %lx\n",
type,addr,(unsigned int )ptr,val);
break;
#elif defined(TCC_TARGET_C67)
case R_C60_32:
*(int *)ptr += val;
break;
case R_C60LO16:
{
uint32_t orig;
/* put the low 16 bits of the absolute address */
// add to what is already there
orig = ((*(int *)(ptr )) >> 7) & 0xffff;
orig |= (((*(int *)(ptr+4)) >> 7) & 0xffff) << 16;
//patch both at once - assumes always in pairs Low - High
*(int *) ptr = (*(int *) ptr & (~(0xffff << 7)) ) | (((val+orig) & 0xffff) << 7);
*(int *)(ptr+4) = (*(int *)(ptr+4) & (~(0xffff << 7)) ) | ((((val+orig)>>16) & 0xffff) << 7);
}
break;
case R_C60HI16:
break;
default:
fprintf(stderr,"FIXME: handle reloc type %x at %lx [%.8x] to %lx\n",
type,addr,(unsigned int )ptr,val);
break;
#elif defined(TCC_TARGET_X86_64)
case R_X86_64_64:
if (s1->output_type == TCC_OUTPUT_DLL) {
qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
qrel->r_addend = *(long long *)ptr + val;
qrel++;
}
*(long long *)ptr += val;
break;
case R_X86_64_32:
case R_X86_64_32S:
if (s1->output_type == TCC_OUTPUT_DLL) {
/* XXX: this logic may depend on TCC's codegen
now TCC uses R_X86_64_32 even for a 64bit pointer */
qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
qrel->r_addend = *(int *)ptr + val;
qrel++;
}
*(int *)ptr += val;
break;
case R_X86_64_PC32: {
if (s1->output_type == TCC_OUTPUT_DLL) {
/* DLL relocation */
esym_index = s1->symtab_to_dynsym[sym_index];
if (esym_index) {
qrel->r_offset = rel->r_offset;
qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC32);
qrel->r_addend = *(int *)ptr;
qrel++;
break;
}
}
long diff = val - addr;
if (diff <= -2147483647 || diff > 2147483647) {
/* XXX: naive support for over 32bit jump */
if (s1->output_type == TCC_OUTPUT_MEMORY) {
val = add_jmp_table(s1, val);
diff = val - addr;
}
if (diff <= -2147483647 || diff > 2147483647) {
error("internal error: relocation failed");
}
}
*(int *)ptr += diff;
}
break;
case R_X86_64_PLT32:
*(int *)ptr += val - addr;
break;
case R_X86_64_GLOB_DAT:
case R_X86_64_JUMP_SLOT:
*(int *)ptr = val;
break;
case R_X86_64_GOTPCREL:
if (s1->output_type == TCC_OUTPUT_MEMORY) {
val = add_got_table(s1, val - rel->r_addend) + rel->r_addend;
*(int *)ptr += val - addr;
break;
}
*(int *)ptr += (s1->got->sh_addr - addr +
s1->got_offsets[sym_index] - 4);
break;
case R_X86_64_GOTTPOFF:
*(int *)ptr += val - s1->got->sh_addr;
break;
case R_X86_64_GOT32:
/* we load the got offset */
*(int *)ptr += s1->got_offsets[sym_index];
break;
#else
#error unsupported processor
#endif
}
}
/* if the relocation is allocated, we change its symbol table */
if (sr->sh_flags & SHF_ALLOC)
sr->link = s1->dynsym;
}
/* relocate relocation table in 'sr' */
static void relocate_rel(TCCState *s1, Section *sr)
{
Section *s;
ElfW_Rel *rel, *rel_end;
s = s1->sections[sr->sh_info];
rel_end = (ElfW_Rel *)(sr->data + sr->data_offset);
for(rel = (ElfW_Rel *)sr->data;
rel < rel_end;
rel++) {
rel->r_offset += s->sh_addr;
}
}
/* count the number of dynamic relocations so that we can reserve
their space */
static int prepare_dynamic_rel(TCCState *s1, Section *sr)
{
ElfW_Rel *rel, *rel_end;
int sym_index, esym_index, type, count;
count = 0;
rel_end = (ElfW_Rel *)(sr->data + sr->data_offset);
for(rel = (ElfW_Rel *)sr->data; rel < rel_end; rel++) {
sym_index = ELFW(R_SYM)(rel->r_info);
type = ELFW(R_TYPE)(rel->r_info);
switch(type) {
#if defined(TCC_TARGET_I386)
case R_386_32:
#elif defined(TCC_TARGET_X86_64)
case R_X86_64_32:
case R_X86_64_32S:
case R_X86_64_64:
#endif
count++;
break;
#if defined(TCC_TARGET_I386)
case R_386_PC32:
#elif defined(TCC_TARGET_X86_64)
case R_X86_64_PC32:
#endif
esym_index = s1->symtab_to_dynsym[sym_index];
if (esym_index)
count++;
break;
default:
break;
}
}
if (count) {
/* allocate the section */
sr->sh_flags |= SHF_ALLOC;
sr->sh_size = count * sizeof(ElfW_Rel);
}
return count;
}
static void put_got_offset(TCCState *s1, int index, unsigned long val)
{
int n;
unsigned long *tab;
if (index >= s1->nb_got_offsets) {
/* find immediately bigger power of 2 and reallocate array */
n = 1;
while (index >= n)
n *= 2;
tab = tcc_realloc(s1->got_offsets, n * sizeof(unsigned long));
if (!tab)
error("memory full");
s1->got_offsets = tab;
memset(s1->got_offsets + s1->nb_got_offsets, 0,
(n - s1->nb_got_offsets) * sizeof(unsigned long));
s1->nb_got_offsets = n;
}
s1->got_offsets[index] = val;
}
/* XXX: suppress that */
static void put32(unsigned char *p, uint32_t val)
{
p[0] = val;
p[1] = val >> 8;
p[2] = val >> 16;
p[3] = val >> 24;
}
#if defined(TCC_TARGET_I386) || defined(TCC_TARGET_ARM) || \
defined(TCC_TARGET_X86_64)
static uint32_t get32(unsigned char *p)
{
return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
}
#endif
static void build_got(TCCState *s1)
{
unsigned char *ptr;
/* if no got, then create it */
s1->got = new_section(s1, ".got", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
s1->got->sh_entsize = 4;
add_elf_sym(symtab_section, 0, 4, ELFW(ST_INFO)(STB_GLOBAL, STT_OBJECT),
0, s1->got->sh_num, "_GLOBAL_OFFSET_TABLE_");
ptr = section_ptr_add(s1->got, 3 * PTR_SIZE);
#if PTR_SIZE == 4
/* keep space for _DYNAMIC pointer, if present */
put32(ptr, 0);
/* two dummy got entries */
put32(ptr + 4, 0);
put32(ptr + 8, 0);
#else
/* keep space for _DYNAMIC pointer, if present */
put32(ptr, 0);
put32(ptr + 4, 0);
/* two dummy got entries */
put32(ptr + 8, 0);
put32(ptr + 12, 0);
put32(ptr + 16, 0);
put32(ptr + 20, 0);
#endif
}
/* put a got entry corresponding to a symbol in symtab_section. 'size'
and 'info' can be modifed if more precise info comes from the DLL */
static void put_got_entry(TCCState *s1,
int reloc_type, unsigned long size, int info,
int sym_index)
{
int index;
const char *name;
ElfW(Sym) *sym;
unsigned long offset;
int *ptr;
if (!s1->got)
build_got(s1);
/* if a got entry already exists for that symbol, no need to add one */
if (sym_index < s1->nb_got_offsets &&
s1->got_offsets[sym_index] != 0)
return;
put_got_offset(s1, sym_index, s1->got->data_offset);
if (s1->dynsym) {
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
name = symtab_section->link->data + sym->st_name;
offset = sym->st_value;
#if defined(TCC_TARGET_I386) || defined(TCC_TARGET_X86_64)
if (reloc_type ==
#ifdef TCC_TARGET_X86_64
R_X86_64_JUMP_SLOT
#else
R_386_JMP_SLOT
#endif
) {
Section *plt;
uint8_t *p;
int modrm;
#if defined(TCC_OUTPUT_DLL_WITH_PLT)
modrm = 0x25;
#else
/* if we build a DLL, we add a %ebx offset */
if (s1->output_type == TCC_OUTPUT_DLL)
modrm = 0xa3;
else
modrm = 0x25;
#endif
/* add a PLT entry */
plt = s1->plt;
if (plt->data_offset == 0) {
/* first plt entry */
p = section_ptr_add(plt, 16);
p[0] = 0xff; /* pushl got + PTR_SIZE */
p[1] = modrm + 0x10;
put32(p + 2, PTR_SIZE);
p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
p[7] = modrm;
put32(p + 8, PTR_SIZE * 2);
}
p = section_ptr_add(plt, 16);
p[0] = 0xff; /* jmp *(got + x) */
p[1] = modrm;
put32(p + 2, s1->got->data_offset);
p[6] = 0x68; /* push $xxx */
put32(p + 7, (plt->data_offset - 32) >> 1);
p[11] = 0xe9; /* jmp plt_start */
put32(p + 12, -(plt->data_offset));
/* the symbol is modified so that it will be relocated to
the PLT */
#if !defined(TCC_OUTPUT_DLL_WITH_PLT)
if (s1->output_type == TCC_OUTPUT_EXE)
#endif
offset = plt->data_offset - 16;
}
#elif defined(TCC_TARGET_ARM)
if (reloc_type == R_ARM_JUMP_SLOT) {
Section *plt;
uint8_t *p;
/* if we build a DLL, we add a %ebx offset */
if (s1->output_type == TCC_OUTPUT_DLL)
error("DLLs unimplemented!");
/* add a PLT entry */
plt = s1->plt;
if (plt->data_offset == 0) {
/* first plt entry */
p = section_ptr_add(plt, 16);
put32(p , 0xe52de004);
put32(p + 4, 0xe59fe010);
put32(p + 8, 0xe08fe00e);
put32(p + 12, 0xe5bef008);
}
p = section_ptr_add(plt, 16);
put32(p , 0xe59fc004);
put32(p+4, 0xe08fc00c);
put32(p+8, 0xe59cf000);
put32(p+12, s1->got->data_offset);
/* the symbol is modified so that it will be relocated to
the PLT */
if (s1->output_type == TCC_OUTPUT_EXE)
offset = plt->data_offset - 16;
}
#elif defined(TCC_TARGET_C67)
error("C67 got not implemented");
#else
#error unsupported CPU
#endif
index = put_elf_sym(s1->dynsym, offset,
size, info, 0, sym->st_shndx, name);
/* put a got entry */
put_elf_reloc(s1->dynsym, s1->got,
s1->got->data_offset,
reloc_type, index);
}
ptr = section_ptr_add(s1->got, PTR_SIZE);
*ptr = 0;
}
/* build GOT and PLT entries */
static void build_got_entries(TCCState *s1)
{
Section *s, *symtab;
ElfW_Rel *rel, *rel_end;
ElfW(Sym) *sym;
int i, type, reloc_type, sym_index;
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if (s->sh_type != SHT_RELX)
continue;
/* no need to handle got relocations */
if (s->link != symtab_section)
continue;
symtab = s->link;