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x86-64: Restore PIC check for PCREL reloc against protected symbol

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commit bd7ab16b45
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Tue Feb 13 07:34:22 2018 -0800

    x86-64: Generate branch with PLT32 relocation

removed check R_X86_64_PC32 relocation against protected symbols in
shared objects.  Since elf_x86_64_check_relocs is called after we
have seen all input files, we can check for PC-relative relocations in
elf_x86_64_check_relocs.  We should not allow PC-relative relocations
against protected symbols since address of protected function and
location of protected data may not be in the shared object.

bfd/

	PR ld/24151
	* elf64-x86-64.c (elf_x86_64_need_pic): Check
	SYMBOL_DEFINED_NON_SHARED_P instead of def_regular.
	(elf_x86_64_relocate_section): Move PIC check for PC-relative
	relocations to ...
	(elf_x86_64_check_relocs): Here.
	(elf_x86_64_finish_dynamic_symbol): Use SYMBOL_DEFINED_NON_SHARED_P
	to check if a symbol is defined in a non-shared object.
	* elfxx-x86.h (SYMBOL_DEFINED_NON_SHARED_P): New.

ld/

	PR ld/24151
	* testsuite/ld-x86-64/pr24151a-x32.d: New file.
	* testsuite/ld-x86-64/pr24151a.d: Likewise.
	* testsuite/ld-x86-64/pr24151a.s: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run pr24151a and pr24151a-x32.
This commit is contained in:
H.J. Lu 2019-02-05 18:45:23 -08:00
parent 4e9ac437aa
commit 83924b3846
8 changed files with 124 additions and 54 deletions
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12
bfd/ChangeLog
View File

@ -1,3 +1,15 @@
2019-02-05 H.J. Lu <hongjiu.lu@intel.com>
PR ld/24151
* elf64-x86-64.c (elf_x86_64_need_pic): Check
SYMBOL_DEFINED_NON_SHARED_P instead of def_regular.
(elf_x86_64_relocate_section): Move PIC check for PC-relative
relocations to ...
(elf_x86_64_check_relocs): Here.
(elf_x86_64_finish_dynamic_symbol): Use SYMBOL_DEFINED_NON_SHARED_P
to check if a symbol is defined in a non-shared object.
* elfxx-x86.h (SYMBOL_DEFINED_NON_SHARED_P): New.
2019-01-21 Sergio Durigan Junior <sergiodj@redhat.com>
* elf32-arm.c (elf32_arm_final_link_relocate): Use 'llabs' instead

133
bfd/elf64-x86-64.c
View File

@ -1426,7 +1426,7 @@ elf_x86_64_need_pic (struct bfd_link_info *info,
break;
}
if (!h->def_regular && !h->def_dynamic)
if (!SYMBOL_DEFINED_NON_SHARED_P (h) && !h->def_dynamic)
und = _("undefined ");
}
else
@ -1855,6 +1855,7 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
const char *name;
bfd_boolean size_reloc;
bfd_boolean converted_reloc;
bfd_boolean do_check_pic;
r_symndx = htab->r_sym (rel->r_info);
r_type = ELF32_R_TYPE (rel->r_info);
@ -2130,6 +2131,13 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
size_reloc = TRUE;
goto do_size;
case R_X86_64_PC8:
case R_X86_64_PC16:
case R_X86_64_PC32:
case R_X86_64_PC32_BND:
do_check_pic = TRUE;
goto check_pic;
case R_X86_64_32:
if (!ABI_64_P (abfd))
goto pointer;
@ -2153,13 +2161,11 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
&x86_64_elf_howto_table[r_type]);
/* Fall through. */
case R_X86_64_PC8:
case R_X86_64_PC16:
case R_X86_64_PC32:
case R_X86_64_PC32_BND:
case R_X86_64_PC64:
case R_X86_64_64:
pointer:
do_check_pic = FALSE;
check_pic:
if (eh != NULL && (sec->flags & SEC_CODE) != 0)
eh->zero_undefweak |= 0x2;
/* We are called after all symbols have been resolved. Only
@ -2223,6 +2229,67 @@ pointer:
}
}
if (do_check_pic)
{
/* Don't complain about -fPIC if the symbol is undefined
when building executable unless it is unresolved weak
symbol, references a dynamic definition in PIE or
-z nocopyreloc is used. */
bfd_boolean no_copyreloc_p
= (info->nocopyreloc
|| (h != NULL
&& eh->def_protected
&& elf_has_no_copy_on_protected (h->root.u.def.section->owner)));
if ((sec->flags & SEC_ALLOC) != 0
&& (sec->flags & SEC_READONLY) != 0
&& h != NULL
&& ((bfd_link_executable (info)
&& ((h->root.type == bfd_link_hash_undefweak
&& (eh == NULL
|| !UNDEFINED_WEAK_RESOLVED_TO_ZERO (info,
eh)))
|| (bfd_link_pie (info)
&& !SYMBOL_DEFINED_NON_SHARED_P (h)
&& h->def_dynamic)
|| (no_copyreloc_p
&& h->def_dynamic
&& !(h->root.u.def.section->flags & SEC_CODE))))
|| bfd_link_dll (info)))
{
bfd_boolean fail = FALSE;
if (SYMBOL_REFERENCES_LOCAL_P (info, h))
{
/* Symbol is referenced locally. Make sure it is
defined locally. */
fail = !SYMBOL_DEFINED_NON_SHARED_P (h);
}
else if (bfd_link_pie (info))
{
/* We can only use PC-relative relocations in PIE
from non-code sections. */
if (h->type == STT_FUNC
&& (sec->flags & SEC_CODE) != 0)
fail = TRUE;
}
else if (no_copyreloc_p || bfd_link_dll (info))
{
/* Symbol doesn't need copy reloc and isn't
referenced locally. Don't allow PC-relative
relocations against default and protected
symbols since address of protected function
and location of protected data may not be in
the shared object. */
fail = (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
|| ELF_ST_VISIBILITY (h->other) == STV_PROTECTED);
}
if (fail)
return elf_x86_64_need_pic (info, abfd, sec, h,
symtab_hdr, isym,
&x86_64_elf_howto_table[r_type]);
}
}
size_reloc = FALSE;
do_size:
if (NEED_DYNAMIC_RELOCATION_P (info, TRUE, h, sec, r_type,
@ -3065,56 +3132,14 @@ use_plt:
case R_X86_64_PC16:
case R_X86_64_PC32:
case R_X86_64_PC32_BND:
/* Don't complain about -fPIC if the symbol is undefined when
building executable unless it is unresolved weak symbol,
references a dynamic definition in PIE or -z nocopyreloc
is used. */
if ((input_section->flags & SEC_ALLOC) != 0
&& (input_section->flags & SEC_READONLY) != 0
&& h != NULL
&& ((bfd_link_executable (info)
&& ((h->root.type == bfd_link_hash_undefweak
&& !resolved_to_zero)
|| (bfd_link_pie (info)
&& !h->def_regular
&& h->def_dynamic)
|| ((info->nocopyreloc
|| (eh->def_protected
&& elf_has_no_copy_on_protected (h->root.u.def.section->owner)))
&& h->def_dynamic
&& !(h->root.u.def.section->flags & SEC_CODE))))
|| bfd_link_dll (info)))
{
bfd_boolean fail = FALSE;
if (SYMBOL_REFERENCES_LOCAL_P (info, h))
{
/* Symbol is referenced locally. Make sure it is
defined locally. */
fail = !(h->def_regular || ELF_COMMON_DEF_P (h));
}
else if (!(bfd_link_pie (info)
&& (h->needs_copy || eh->needs_copy)))
{
/* Symbol doesn't need copy reloc and isn't referenced
locally. Address of protected function may not be
reachable at run-time. */
fail = (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
|| (ELF_ST_VISIBILITY (h->other) == STV_PROTECTED
&& h->type == STT_FUNC));
}
if (fail)
return elf_x86_64_need_pic (info, input_bfd, input_section,
h, NULL, NULL, howto);
}
/* Since x86-64 has PC-relative PLT, we can use PLT in PIE
as function address. */
else if (h != NULL
&& (input_section->flags & SEC_CODE) == 0
&& bfd_link_pie (info)
&& h->type == STT_FUNC
&& !h->def_regular
&& h->def_dynamic)
if (h != NULL
&& (input_section->flags & SEC_CODE) == 0
&& bfd_link_pie (info)
&& h->type == STT_FUNC
&& !h->def_regular
&& h->def_dynamic)
goto use_plt;
/* Fall through. */
@ -4271,7 +4296,7 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
else if (bfd_link_pic (info)
&& SYMBOL_REFERENCES_LOCAL_P (info, h))
{
if (!(h->def_regular || ELF_COMMON_DEF_P (h)))
if (!SYMBOL_DEFINED_NON_SHARED_P (h))
return FALSE;
BFD_ASSERT((h->got.offset & 1) != 0);
rela.r_info = htab->r_info (0, R_X86_64_RELATIVE);

7
bfd/elfxx-x86.h
View File

@ -161,6 +161,13 @@
|| (ELF_ST_VISIBILITY ((H)->other) \
&& (H)->root.type == bfd_link_hash_undefweak))
/* TRUE if this symbol isn't defined by a shared object. */
#define SYMBOL_DEFINED_NON_SHARED_P(H) \
((H)->def_regular \
|| (H)->root.linker_def \
|| (H)->root.ldscript_def \
|| ELF_COMMON_DEF_P (H))
/* TRUE if relative relocation should be generated. GOT reference to
global symbol in PIC will lead to dynamic symbol. It becomes a
problem when "time" or "times" is defined as a variable in an

8
ld/ChangeLog
View File

@ -1,3 +1,11 @@
2019-02-05 H.J. Lu <hongjiu.lu@intel.com>
PR ld/24151
* testsuite/ld-x86-64/pr24151a-x32.d: New file.
* testsuite/ld-x86-64/pr24151a.d: Likewise.
* testsuite/ld-x86-64/pr24151a.s: Likewise.
* testsuite/ld-x86-64/x86-64.exp: Run pr24151a and pr24151a-x32.
2019-01-31 Alan Modra <amodra@gmail.com>
* NEWS: Mention -t change.

4
ld/testsuite/ld-x86-64/pr24151a-x32.d Normal file
View File

@ -0,0 +1,4 @@
#source: pr24151a.s
#as: --x32
#ld: -shared -melf32_x86_64
#error: .*relocation R_X86_64_PC32 against protected symbol `foo' can not be used when making a shared object

3
ld/testsuite/ld-x86-64/pr24151a.d Normal file
View File

@ -0,0 +1,3 @@
#as: --64
#ld: -shared -melf_x86_64
#error: .*relocation R_X86_64_PC32 against protected symbol `foo' can not be used when making a shared object

9
ld/testsuite/ld-x86-64/pr24151a.s Normal file
View File

@ -0,0 +1,9 @@
.text
.globl bar
.type bar,@function
bar:
movl $30, foo(%rip)
.size bar, .-bar
.protected foo
.type foo,@object
.comm foo,4,4

2
ld/testsuite/ld-x86-64/x86-64.exp
View File

@ -424,6 +424,8 @@ run_dump_test "pr23486d-x32"
run_dump_test "pr23854"
run_dump_test "pr23930"
run_dump_test "pr23930-x32"
run_dump_test "pr24151a"
run_dump_test "pr24151a-x32"
if { ![istarget "x86_64-*-linux*"] && ![istarget "x86_64-*-nacl*"]} {
return