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ELF64: GOT and PLT references need a symbol (a slot!) to reference

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GOT and PLT references need a symbol; after all, they reference a GOT
or PLT slot.  Thus, they need elf_add_gsym_reloc().  Mungify the
interface so that they can communicate the need for the PC-shifted
offset into the relocation.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2008-10-17 20:01:16 -07:00
parent 8140afbaf1
commit 70e6c2a6cb
1 changed files with 33 additions and 26 deletions
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59
output/outelf64.c
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@ -820,9 +820,9 @@ static void elf_add_reloc(struct Section *sect, int32_t segment,
* Inefficiency: we search, currently, using a linked list which
* isn't even necessarily sorted.
*/
static int64_t elf_add_gsym_reloc(struct Section *sect,
int32_t segment, int64_t offset,
int type, bool exact)
static void elf_add_gsym_reloc(struct Section *sect,
int32_t segment, int64_t offset, int64_t pcrel,
int type, bool exact)
{
struct Reloc *r;
struct Section *s;
@ -842,9 +842,13 @@ static int64_t elf_add_gsym_reloc(struct Section *sect,
s = sects[i];
break;
}
if (!s) {
elf_add_reloc(sect, segment, offset, type);
return offset;
if (exact && offset)
error(ERR_NONFATAL, "invalid access to an external symbol");
else
elf_add_reloc(sect, segment, offset - pcrel, type);
return;
}
if (exact) {
@ -854,6 +858,11 @@ static int64_t elf_add_gsym_reloc(struct Section *sect,
for (sym = s->gsyms; sym; sym = sym->next)
if (sym->value == offset)
break;
if (!sym) {
error(ERR_NONFATAL, "unable to find a suitable global symbol"
" for this reference");
return;
}
} else {
/*
* Find the nearest symbol below this one.
@ -863,24 +872,17 @@ static int64_t elf_add_gsym_reloc(struct Section *sect,
if (sm->value <= offset && (!sym || sm->value > sym->value))
sym = sm;
}
if (!sym && exact) {
error(ERR_NONFATAL, "unable to find a suitable global symbol"
" for this reference");
return 0;
}
r = *sect->tail = nasm_malloc(sizeof(struct Reloc));
sect->tail = &r->next;
r->next = NULL;
r->address = sect->len;
r->offset = offset - sym->value;
r->offset = offset - pcrel - sym->value;
r->symbol = GLOBAL_TEMP_BASE + sym->globnum;
r->type = type;
sect->nrelocs++;
return offset - sym->value;
}
static void elf_out(int32_t segto, const void *data,
@ -1010,18 +1012,19 @@ static void elf_out(int32_t segto, const void *data,
error(ERR_NONFATAL, "ELF64 requires ..gotoff "
"references to be qword absolute");
} else {
elf_add_reloc(s, segment, addr, R_X86_64_GOTOFF64);
elf_add_gsym_reloc(s, segment, addr, 0,
R_X86_64_GOTOFF64, true);
addr = 0;
}
} else if (wrt == elf_got_sect + 1) {
switch ((int)size) {
case 4:
elf_add_gsym_reloc(s, segment, addr,
elf_add_gsym_reloc(s, segment, addr, 0,
R_X86_64_GOT32, true);
addr = 0;
break;
case 8:
elf_add_gsym_reloc(s, segment, addr,
elf_add_gsym_reloc(s, segment, addr, 0,
R_X86_64_GOT64, true);
addr = 0;
break;
@ -1032,22 +1035,22 @@ static void elf_out(int32_t segto, const void *data,
} else if (wrt == elf_sym_sect + 1) {
switch ((int)size) {
case 1:
elf_add_gsym_reloc(s, segment, addr,
elf_add_gsym_reloc(s, segment, addr, 0,
R_X86_64_8, false);
addr = 0;
break;
case 2:
elf_add_gsym_reloc(s, segment, addr,
elf_add_gsym_reloc(s, segment, addr, 0,
R_X86_64_16, false);
addr = 0;
break;
case 4:
elf_add_gsym_reloc(s, segment, addr,
elf_add_gsym_reloc(s, segment, addr, 0,
R_X86_64_32, false);
addr = 0;
break;
case 8:
elf_add_gsym_reloc(s, segment, addr,
elf_add_gsym_reloc(s, segment, addr, 0,
R_X86_64_64, false);
addr = 0;
break;
@ -1097,11 +1100,15 @@ static void elf_out(int32_t segto, const void *data,
elf_add_reloc(s, segment, addr, R_X86_64_PC32);
addr = 0;
} else if (wrt == elf_plt_sect + 1) {
elf_add_reloc(s, segment, addr, R_X86_64_PLT32);
int64_t pcrel = s->len + size;
elf_add_gsym_reloc(s, segment, addr+pcrel, pcrel,
R_X86_64_PLT32, false);
addr = 0;
} else if (wrt == elf_gotpc_sect + 1 ||
wrt == elf_got_sect + 1) {
elf_add_reloc(s, segment, addr, R_X86_64_GOTPCREL);
int64_t pcrel = s->len + size;
elf_add_gsym_reloc(s, segment, addr+pcrel, pcrel,
R_X86_64_GOTPCREL, false);
addr = 0;
} else if (wrt == elf_gotoff_sect + 1 ||
wrt == elf_got_sect + 1) {
@ -1124,13 +1131,13 @@ static void elf_out(int32_t segto, const void *data,
" segment base references");
} else {
if (wrt == NO_SEG) {
elf_add_reloc(s, segment, *(int64_t *)data - size,
R_X86_64_PC64);
elf_add_reloc(s, segment, addr, R_X86_64_PC64);
addr = 0;
} else if (wrt == elf_gotpc_sect + 1 ||
wrt == elf_got_sect + 1) {
elf_add_reloc(s, segment, *(int64_t *)data - size,
R_X86_64_GOTPCREL64);
int64_t pcrel = s->len + size;
elf_add_gsym_reloc(s, segment, addr+pcrel, pcrel,
R_X86_64_GOTPCREL64, false);
addr = 0;
} else if (wrt == elf_gotoff_sect + 1 ||
wrt == elf_got_sect + 1) {