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x86: Remove func_pointer_refcount 

Since check_reloc is running after gc_sections, there is no need for
reference count.  If a function pointer relocation can be resolved at
run-time, there is no need for PLT and it doesn't count as non-GOT/PLT
relocation.  func_pointer_refcount can be removed.

	* elf32-i386.c (elf_i386_check_relocs): Set plt.refcount to 1.
	Don't use func_pointer_refcount.  Don't set plt.refcount nor
	non_got_ref for function pointer reference.
	* elf64-x86-64.c (elf_x86_64_check_relocs): Likewise.
	* elfxx-x86.c (elf_x86_allocate_dynrelocs): Don't use
	func_pointer_refcount.
	(_bfd_x86_elf_copy_indirect_symbol): Don't copy
	func_pointer_refcount.
	(_bfd_x86_elf_hide_symbol): Don't use func_pointer_refcount.
	* elfxx-x86.h (GENERATE_DYNAMIC_RELOCATION_P): Likewise.
	(elf_x86_link_hash_entry): Remove func_pointer_refcount.
This commit is contained in:
H.J. Lu 2017-11-03 11:14:56 -07:00
parent 67fa57cfa5
commit 79b0c981b8
5 changed files with 60 additions and 60 deletions
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14
bfd/ChangeLog
View File

@ -1,3 +1,17 @@
2017-11-03 H.J. Lu <hongjiu.lu@intel.com>
* elf32-i386.c (elf_i386_check_relocs): Set plt.refcount to 1.
Don't use func_pointer_refcount. Don't set plt.refcount nor
non_got_ref for function pointer reference.
* elf64-x86-64.c (elf_x86_64_check_relocs): Likewise.
* elfxx-x86.c (elf_x86_allocate_dynrelocs): Don't use
func_pointer_refcount.
(_bfd_x86_elf_copy_indirect_symbol): Don't copy
func_pointer_refcount.
(_bfd_x86_elf_hide_symbol): Don't use func_pointer_refcount.
* elfxx-x86.h (GENERATE_DYNAMIC_RELOCATION_P): Likewise.
(elf_x86_link_hash_entry): Remove func_pointer_refcount.
2017-11-03 Mingi Cho <mgcho.minic@gmail.com>
Nick Clifton <nickc@redhat.com>

37
bfd/elf32-i386.c
View File

@ -1600,7 +1600,7 @@ elf_i386_check_relocs (bfd *abfd,
eh->zero_undefweak &= 0x2;
h->needs_plt = 1;
h->plt.refcount += 1;
h->plt.refcount = 1;
break;
case R_386_SIZE32:
@ -1751,20 +1751,7 @@ do_relocation:
&& (bfd_link_executable (info)
|| h->type == STT_GNU_IFUNC))
{
/* If this reloc is in a read-only section, we might
need a copy reloc. We can't check reliably at this
stage whether the section is read-only, as input
sections have not yet been mapped to output sections.
Tentatively set the flag for now, and correct in
adjust_dynamic_symbol. */
h->non_got_ref = 1;
/* We may need a .plt entry if the symbol is a function
defined in a shared lib or is a STT_GNU_IFUNC function
referenced from the code or read-only section. */
if (!h->def_regular
|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
h->plt.refcount += 1;
bfd_boolean func_pointer_ref = FALSE;
if (r_type == R_386_PC32)
{
@ -1790,7 +1777,25 @@ do_relocation:
/* R_386_32 can be resolved at run-time. */
if (r_type == R_386_32
&& (sec->flags & SEC_READONLY) == 0)
eh->func_pointer_refcount += 1;
func_pointer_ref = TRUE;
}
if (!func_pointer_ref)
{
/* If this reloc is in a read-only section, we might
need a copy reloc. We can't check reliably at this
stage whether the section is read-only, as input
sections have not yet been mapped to output sections.
Tentatively set the flag for now, and correct in
adjust_dynamic_symbol. */
h->non_got_ref = 1;
/* We may need a .plt entry if the symbol is a function
defined in a shared lib or is a function referenced
from the code or read-only section. */
if (!h->def_regular
|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
h->plt.refcount = 1;
}
}

39
bfd/elf64-x86-64.c
View File

@ -2067,7 +2067,7 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
eh->zero_undefweak &= 0x2;
h->needs_plt = 1;
h->plt.refcount += 1;
h->plt.refcount = 1;
break;
case R_X86_64_PLTOFF64:
@ -2076,7 +2076,7 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
if (h != NULL)
{
h->needs_plt = 1;
h->plt.refcount += 1;
h->plt.refcount = 1;
}
goto create_got;
@ -2124,20 +2124,7 @@ pointer:
&& (bfd_link_executable (info)
|| h->type == STT_GNU_IFUNC))
{
/* If this reloc is in a read-only section, we might
need a copy reloc. We can't check reliably at this
stage whether the section is read-only, as input
sections have not yet been mapped to output sections.
Tentatively set the flag for now, and correct in
adjust_dynamic_symbol. */
h->non_got_ref = 1;
/* We may need a .plt entry if the symbol is a function
defined in a shared lib or is a STT_GNU_IFUNC function
referenced from the code or read-only section. */
if (!h->def_regular
|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
h->plt.refcount += 1;
bfd_boolean func_pointer_ref = FALSE;
if (r_type == R_X86_64_PC32)
{
@ -2159,7 +2146,25 @@ pointer:
|| (!ABI_64_P (abfd)
&& (r_type == R_X86_64_32
|| r_type == R_X86_64_32S))))
eh->func_pointer_refcount += 1;
func_pointer_ref = TRUE;
}
if (!func_pointer_ref)
{
/* If this reloc is in a read-only section, we might
need a copy reloc. We can't check reliably at this
stage whether the section is read-only, as input
sections have not yet been mapped to output sections.
Tentatively set the flag for now, and correct in
adjust_dynamic_symbol. */
h->non_got_ref = 1;
/* We may need a .plt entry if the symbol is a function
defined in a shared lib or is a function referenced
from the code or read-only section. */
if (!h->def_regular
|| (sec->flags & (SEC_CODE | SEC_READONLY)) != 0)
h->plt.refcount = 1;
}
}

25
bfd/elfxx-x86.c
View File

@ -108,11 +108,6 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
resolved_to_zero = UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh);
/* Clear the reference count of function pointer relocations if
symbol isn't a normal function. */
if (h->type != STT_FUNC)
eh->func_pointer_refcount = 0;
/* We can't use the GOT PLT if pointer equality is needed since
finish_dynamic_symbol won't clear symbol value and the dynamic
linker won't update the GOT slot. We will get into an infinite
@ -162,15 +157,11 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
/* Don't create the PLT entry if there are only function pointer
relocations which can be resolved at run-time. */
else if (htab->elf.dynamic_sections_created
&& (h->plt.refcount > eh->func_pointer_refcount
&& (h->plt.refcount > 0
|| eh->plt_got.refcount > 0))
{
bfd_boolean use_plt_got = eh->plt_got.refcount > 0;
/* Clear the reference count of function pointer relocations
if PLT is used. */
eh->func_pointer_refcount = 0;
/* Make sure this symbol is output as a dynamic symbol.
Undefined weak syms won't yet be marked as dynamic. */
if (h->dynindx == -1
@ -488,7 +479,6 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
pointer initialization. */
if ((!h->non_got_ref
|| eh->func_pointer_refcount > 0
|| (h->root.type == bfd_link_hash_undefweak
&& !resolved_to_zero))
&& ((h->def_dynamic
@ -513,7 +503,6 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
}
eh->dyn_relocs = NULL;
eh->func_pointer_refcount = 0;
keep: ;
}
@ -1643,15 +1632,7 @@ _bfd_x86_elf_copy_indirect_symbol (struct bfd_link_info *info,
dir->pointer_equality_needed |= ind->pointer_equality_needed;
}
else
{
if (eind->func_pointer_refcount > 0)
{
edir->func_pointer_refcount += eind->func_pointer_refcount;
eind->func_pointer_refcount = 0;
}
_bfd_elf_link_hash_copy_indirect (info, dir, ind);
}
_bfd_elf_link_hash_copy_indirect (info, dir, ind);
}
/* Remove undefined weak symbol from the dynamic symbol table if it
@ -1900,7 +1881,7 @@ _bfd_x86_elf_hide_symbol (struct bfd_link_info *info,
weak symbol dynamic so that PC relative branch to the undefined
weak symbol will land to address 0. */
struct elf_x86_link_hash_entry *eh = elf_x86_hash_entry (h);
if (h->plt.refcount > eh->func_pointer_refcount
if (h->plt.refcount > 0
|| eh->plt_got.refcount > 0)
return;
}

5
bfd/elfxx-x86.h
View File

@ -133,7 +133,6 @@
&& (EH) != NULL \
&& (EH)->elf.dynindx != -1 \
&& (!(EH)->elf.non_got_ref \
|| (EH)->func_pointer_refcount > 0 \
|| ((EH)->elf.root.type == bfd_link_hash_undefweak \
&& !(RESOLVED_TO_ZERO))) \
&& (((EH)->elf.def_dynamic && !(EH)->elf.def_regular) \
@ -268,10 +267,6 @@ struct elf_x86_link_hash_entry
is only used by x86-64. */
unsigned int needs_copy : 1;
/* Reference count of C/C++ function pointer relocations in read-write
section which can be resolved at run-time. */
bfd_signed_vma func_pointer_refcount;
/* Information about the GOT PLT entry. Filled when there are both
GOT and PLT relocations against the same function. */
union gotplt_union plt_got;