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ca92bfc3c6
tinycc/i386-link.c
grischka ca92bfc3c6 tccelf: some linker cleanup 
- generate and use SYM@PLT for plt addresses
- get rid of patch_dynsym_undef hack (no idea what it did on FreeBSD)
- use sym_attrs instead of symtab_to_dynsym
- special case for function pointers into .so on i386
- libtcc_test: test tcc_add_symbol with data object
- move target specicic code to *-link.c files
- add R_XXX_RELATIVE (needed for PE)
2016-12-15 17:01:22 +01:00

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#ifdef TARGET_DEFS_ONLY
#define EM_TCC_TARGET EM_386
/* relocation type for 32 bit data relocation */
#define R_DATA_32 R_386_32
#define R_DATA_PTR R_386_32
#define R_JMP_SLOT R_386_JMP_SLOT
#define R_GLOB_DAT R_386_GLOB_DAT
#define R_COPY R_386_COPY
#define R_NUM R_386_NUM
#define ELF_START_ADDR 0x08048000
#define ELF_PAGE_SIZE 0x1000
#define PCRELATIVE_DLLPLT 0
#define RELOCATE_DLLPLT 0
#else /* !TARGET_DEFS_ONLY */
#include "tcc.h"
/* Returns 1 for a code relocation, 0 for a data relocation. For unknown
relocations, returns -1. */
int code_reloc (int reloc_type)
{
switch (reloc_type) {
case R_386_RELATIVE:
case R_386_16:
case R_386_32:
case R_386_GOTPC:
case R_386_GOTOFF:
case R_386_GOT32:
case R_386_GOT32X:
case R_386_GLOB_DAT:
case R_386_COPY:
return 0;
case R_386_PC16:
case R_386_PC32:
case R_386_PLT32:
case R_386_JMP_SLOT:
return 1;
}
tcc_error ("Unknown relocation type: %d", reloc_type);
return -1;
}
/* Returns an enumerator to describe wether and when the relocation needs a
GOT and/or PLT entry to be created. See tcc.h for a description of the
different values. */
int gotplt_entry_type (int reloc_type)
{
switch (reloc_type) {
case R_386_RELATIVE:
case R_386_16:
case R_386_32:
case R_386_GLOB_DAT:
case R_386_JMP_SLOT:
case R_386_COPY:
return NO_GOTPLT_ENTRY;
case R_386_PC16:
case R_386_PC32:
return AUTO_GOTPLT_ENTRY;
case R_386_GOTPC:
case R_386_GOTOFF:
return BUILD_GOT_ONLY;
case R_386_GOT32:
case R_386_GOT32X:
case R_386_PLT32:
return ALWAYS_GOTPLT_ENTRY;
}
tcc_error ("Unknown relocation type: %d", reloc_type);
return -1;
}
ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
{
Section *plt = s1->plt;
uint8_t *p;
int modrm;
unsigned plt_offset, relofs;
/* on i386 if we build a DLL, we add a %ebx offset */
if (s1->output_type == TCC_OUTPUT_DLL)
modrm = 0xa3;
else
modrm = 0x25;
/* empty PLT: create PLT0 entry that pushes the library indentifier
(GOT + PTR_SIZE) and jumps to ld.so resolution routine
(GOT + 2 * PTR_SIZE) */
if (plt->data_offset == 0) {
p = section_ptr_add(plt, 16);
p[0] = 0xff; /* pushl got + PTR_SIZE */
p[1] = modrm + 0x10;
write32le(p + 2, PTR_SIZE);
p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
p[7] = modrm;
write32le(p + 8, PTR_SIZE * 2);
}
plt_offset = plt->data_offset;
/* The PLT slot refers to the relocation entry it needs via offset.
The reloc entry is created below, so its offset is the current
data_offset */
relofs = s1->got->reloc ? s1->got->reloc->data_offset : 0;
/* Jump to GOT entry where ld.so initially put the address of ip + 4 */
p = section_ptr_add(plt, 16);
p[0] = 0xff; /* jmp *(got + x) */
p[1] = modrm;
write32le(p + 2, got_offset);
p[6] = 0x68; /* push $xxx */
write32le(p + 7, relofs);
p[11] = 0xe9; /* jmp plt_start */
write32le(p + 12, -(plt->data_offset));
return plt_offset;
}
/* relocate the PLT: compute addresses and offsets in the PLT now that final
address for PLT and GOT are known (see fill_program_header) */
ST_FUNC void relocate_plt(TCCState *s1)
{
uint8_t *p, *p_end;
if (!s1->plt)
return;
p = s1->plt->data;
p_end = p + s1->plt->data_offset;
if (p < p_end) {
add32le(p + 2, s1->got->sh_addr);
add32le(p + 8, s1->got->sh_addr);
p += 16;
while (p < p_end) {
add32le(p + 2, s1->got->sh_addr);
p += 16;
}
}
}
static ElfW_Rel *qrel; /* ptr to next reloc entry reused */
void relocate_init(Section *sr)
{
qrel = (ElfW_Rel *) sr->data;
}
void relocate(TCCState *s1, ElfW_Rel *rel, int type, char *ptr, addr_t addr, addr_t val)
{
int sym_index, esym_index;
sym_index = ELFW(R_SYM)(rel->r_info);
switch (type) {
case R_386_32:
if (s1->output_type == TCC_OUTPUT_DLL) {
esym_index = s1->sym_attrs[sym_index].dyn_index;
qrel->r_offset = rel->r_offset;
if (esym_index) {
qrel->r_info = ELFW(R_INFO)(esym_index, R_386_32);
qrel++;
return;
} else {
qrel->r_info = ELFW(R_INFO)(0, R_386_RELATIVE);
qrel++;
}
}
add32le(ptr, val);
return;
case R_386_PC32:
if (s1->output_type == TCC_OUTPUT_DLL) {
/* DLL relocation */
esym_index = s1->sym_attrs[sym_index].dyn_index;
if (esym_index) {
qrel->r_offset = rel->r_offset;
qrel->r_info = ELFW(R_INFO)(esym_index, R_386_PC32);
qrel++;
return;
}
}
add32le(ptr, val - addr);
return;
case R_386_PLT32:
add32le(ptr, val - addr);
return;
case R_386_GLOB_DAT:
case R_386_JMP_SLOT:
write32le(ptr, val);
return;
case R_386_GOTPC:
add32le(ptr, s1->got->sh_addr - addr);
return;
case R_386_GOTOFF:
add32le(ptr, val - s1->got->sh_addr);
return;
case R_386_GOT32:
case R_386_GOT32X:
/* we load the got offset */
add32le(ptr, s1->sym_attrs[sym_index].got_offset);
return;
case R_386_16:
if (s1->output_format != TCC_OUTPUT_FORMAT_BINARY) {
output_file:
tcc_error("can only produce 16-bit binary files");
}
write16le(ptr, read16le(ptr) + val);
return;
case R_386_PC16:
if (s1->output_format != TCC_OUTPUT_FORMAT_BINARY)
goto output_file;
write16le(ptr, read16le(ptr) + val - addr);
return;
case R_386_RELATIVE:
/* do nothing */
return;
case R_386_COPY:
/* This reloction must copy initialized data from the library
to the program .bss segment. Currently made like for ARM
(to remove noise of defaukt case). Is this true?
*/
return;
default:
fprintf(stderr,"FIXME: handle reloc type %d at %x [%p] to %x\n",
type, (unsigned)addr, ptr, (unsigned)val);
return;
}
}
#endif /* !TARGET_DEFS_ONLY */
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