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i386: Avoid dynamic symbol with GOT reference in PIE

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GOT reference to global symbol in PIE will lead to dynamic symbol.  It
becomes a problem when "time" or "times" is defined as a variable in
an executable, clashing with functions of the same name in libc.  If
a symbol isn't undefined weak symbol, don't make it dynamic in PIE and
generate R_386_RELATIVE relocation.

bfd/

	PR ld/21402
	* elf32-i386.c (elf_i386_link_hash_entry): Add
	no_finish_dynamic_symbol.
	(elf_i386_link_hash_newfunc): Set no_finish_dynamic_symbol to 0.
	(elf_i386_allocate_dynrelocs): If a symbol isn't undefined weak
	symbol, don't make it dynamic in PIE.
	(elf_i386_relocate_section): If a symbol isn't dynamic in PIE,
	set no_finish_dynamic_symbol and generate R_386_RELATIVE
	relocation for R_386_GOT32
	(elf_i386_finish_dynamic_symbol): Abort if no_finish_dynamic_symbol
	isn't 0.

ld/

	PR ld/21402
	* testsuite/ld-elf/indirect.exp: Don't skip PIE indirect5 and
	indirect6 tests on i386.
This commit is contained in:
H.J. Lu 2017-04-21 12:03:14 -07:00
parent 3c5fce9bc2
commit e133d00576
4 changed files with 63 additions and 23 deletions
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14
bfd/ChangeLog
View File

@ -1,3 +1,17 @@
2017-04-21 H.J. Lu <hongjiu.lu@intel.com>
PR ld/21402
* elf32-i386.c (elf_i386_link_hash_entry): Add
no_finish_dynamic_symbol.
(elf_i386_link_hash_newfunc): Set no_finish_dynamic_symbol to 0.
(elf_i386_allocate_dynrelocs): If a symbol isn't undefined weak
symbol, don't make it dynamic in PIE.
(elf_i386_relocate_section): If a symbol isn't dynamic in PIE,
set no_finish_dynamic_symbol and generate R_386_RELATIVE
relocation for R_386_GOT32
(elf_i386_finish_dynamic_symbol): Abort if no_finish_dynamic_symbol
isn't 0.
2017-04-21 H.J. Lu <hongjiu.lu@intel.com>
PR ld/19617

61
bfd/elf32-i386.c
View File

@ -820,6 +820,9 @@ struct elf_i386_link_hash_entry
/* Symbol has non-GOT/non-PLT relocations in text sections. */
unsigned int has_non_got_reloc : 1;
/* Don't call finish_dynamic_symbol on this symbol. */
unsigned int no_finish_dynamic_symbol : 1;
/* 0: symbol isn't ___tls_get_addr.
1: symbol is ___tls_get_addr.
2: symbol is unknown. */
@ -959,6 +962,7 @@ elf_i386_link_hash_newfunc (struct bfd_hash_entry *entry,
eh->gotoff_ref = 0;
eh->has_got_reloc = 0;
eh->has_non_got_reloc = 0;
eh->no_finish_dynamic_symbol = 0;
eh->tls_get_addr = 2;
eh->func_pointer_refcount = 0;
eh->plt_got.offset = (bfd_vma) -1;
@ -2863,10 +2867,14 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
int tls_type = elf_i386_hash_entry(h)->tls_type;
/* Make sure this symbol is output as a dynamic symbol.
Undefined weak syms won't yet be marked as dynamic. */
Undefined weak syms won't yet be marked as dynamic.
PR ld/21402: If this symbol isn't undefined weak symbol,
don't make it dynamic in PIE. */
if (h->dynindx == -1
&& !h->forced_local
&& !resolved_to_zero)
&& !resolved_to_zero
&& (h->root.type == bfd_link_hash_undefweak
|| !bfd_link_pie (info)))
{
if (! bfd_elf_link_record_dynamic_symbol (info, h))
return FALSE;
@ -3818,6 +3826,7 @@ elf_i386_relocate_section (bfd *output_bfd,
bfd_vma st_size;
asection *resolved_plt;
bfd_boolean resolved_to_zero;
bfd_boolean relative_reloc;
r_type = ELF32_R_TYPE (rel->r_info);
if (r_type == R_386_GNU_VTINHERIT
@ -4268,6 +4277,7 @@ r_386_got32:
if (htab->elf.sgot == NULL)
abort ();
relative_reloc = FALSE;
if (h != NULL)
{
bfd_boolean dyn;
@ -4301,6 +4311,17 @@ r_386_got32:
bfd_put_32 (output_bfd, relocation,
htab->elf.sgot->contents + off);
h->got.offset |= 1;
if (h->dynindx == -1
&& !h->forced_local
&& h->root.type != bfd_link_hash_undefweak
&& bfd_link_pie (info))
{
/* PR ld/21402: If this symbol isn't dynamic
in PIE, generate R_386_RELATIVE here. */
eh->no_finish_dynamic_symbol = 1;
relative_reloc = TRUE;
}
}
}
else
@ -4322,27 +4343,29 @@ r_386_got32:
{
bfd_put_32 (output_bfd, relocation,
htab->elf.sgot->contents + off);
local_got_offsets[r_symndx] |= 1;
if (bfd_link_pic (info))
{
asection *s;
Elf_Internal_Rela outrel;
s = htab->elf.srelgot;
if (s == NULL)
abort ();
outrel.r_offset = (htab->elf.sgot->output_section->vma
+ htab->elf.sgot->output_offset
+ off);
outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
elf_append_rel (output_bfd, s, &outrel);
}
local_got_offsets[r_symndx] |= 1;
relative_reloc = TRUE;
}
}
if (relative_reloc)
{
asection *s;
Elf_Internal_Rela outrel;
s = htab->elf.srelgot;
if (s == NULL)
abort ();
outrel.r_offset = (htab->elf.sgot->output_section->vma
+ htab->elf.sgot->output_offset
+ off);
outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
elf_append_rel (output_bfd, s, &outrel);
}
if (off >= (bfd_vma) -2)
abort ();
@ -5321,6 +5344,8 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
plt_entry_size = GET_PLT_ENTRY_SIZE (output_bfd);
eh = (struct elf_i386_link_hash_entry *) h;
if (eh->no_finish_dynamic_symbol)
abort ();
/* We keep PLT/GOT entries without dynamic PLT/GOT relocations for
resolved undefined weak symbols in executable so that their

6
ld/ChangeLog
View File

@ -1,3 +1,9 @@
2017-04-21 H.J. Lu <hongjiu.lu@intel.com>
PR ld/21402
* testsuite/ld-elf/indirect.exp: Don't skip PIE indirect5 and
indirect6 tests on i386.
2017-04-21 H.J. Lu <hongjiu.lu@intel.com>
PR ld/19617

5
ld/testsuite/ld-elf/indirect.exp
View File

@ -222,11 +222,6 @@ foreach t [list indirect5a indirect5b indirect6a indirect6b] {
}
}
# PR ld/21402: i386 doesn't support mixing different symbol types in PIE.
if {[istarget "i?86-*-*"]} {
return
}
send_log "$CC -fPIE -pie $srcdir/$subdir/main.c -o tmpdir/pie"
catch "exec $CC -fPIE -pie $srcdir/$subdir/main.c -o tmpdir/pie" exec_output
send_log "$exec_output"