[PATCH] x86: Don't call strncmp for __tls_get_addr
H.J. Lu
hjl.tools@gmail.com
Fri Aug 4 04:26:00 GMT 2017
I am testing this patch.
H.J.
---
Instead of calling strncmp for each symbol, we can check for
__tls_get_addr reference once.
* elf32-i386.c (elf_i386_link_hash_entry): Change tls_get_addr
to 1 bit.
(elf_i386_link_hash_newfunc): Initialize tls_get_addr to 0.
(elf_i386_check_tls_transition): Check tls_get_addr directly.
(elf_i386_convert_load_reloc): Update tls_get_addr check.
(elf_i386_link_check_relocs): New function.
(bfd_elf32_bfd_link_check_relocs): New.
* elf64-x86-64.c (elf_x86_64_link_hash_entry): Change tls_get_addr
to 1 bit.
(elf_x86_64_link_hash_newfunc): Initialize tls_get_addr to 0.
(elf_x86_64_check_tls_transition): Check tls_get_addr directly.
(elf_x86_64_convert_load_reloc): Update tls_get_addr check.
(elf_x86_64_link_check_relocs): New function.
(bfd_elf64_bfd_link_check_relocs): New.
(bfd_elf32_bfd_link_check_relocs): Likewise.
---
bfd/elf32-i386.c | 54 ++++++++++++++++++++++++----------------------------
bfd/elf64-x86-64.c | 56 ++++++++++++++++++++++++++----------------------------
2 files changed, 52 insertions(+), 58 deletions(-)
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index 37099b7557..14f018ea2c 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -995,10 +995,8 @@ struct elf_i386_link_hash_entry
/* 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. */
- unsigned int tls_get_addr : 2;
+ /* TRUE if symbol symbol is __tls_get_addr. */
+ unsigned int tls_get_addr : 1;
/* Reference count of C/C++ function pointer relocations in read-write
section which can be resolved at run-time. */
@@ -1149,7 +1147,7 @@ elf_i386_link_hash_newfunc (struct bfd_hash_entry *entry,
eh->has_got_reloc = 0;
eh->has_non_got_reloc = 0;
eh->no_finish_dynamic_symbol = 0;
- eh->tls_get_addr = 2;
+ eh->tls_get_addr = 0;
eh->func_pointer_refcount = 0;
eh->plt_got.offset = (bfd_vma) -1;
eh->tlsdesc_got = (bfd_vma) -1;
@@ -1378,7 +1376,7 @@ elf_i386_check_tls_transition (asection *sec,
struct elf_link_hash_entry *h;
bfd_vma offset;
bfd_byte *call;
- bfd_boolean indirect_call, tls_get_addr;
+ bfd_boolean indirect_call;
offset = rel->r_offset;
switch (r_type)
@@ -1483,29 +1481,9 @@ elf_i386_check_tls_transition (asection *sec,
if (r_symndx < symtab_hdr->sh_info)
return FALSE;
- tls_get_addr = FALSE;
h = sym_hashes[r_symndx - symtab_hdr->sh_info];
- if (h != NULL && h->root.root.string != NULL)
- {
- struct elf_i386_link_hash_entry *eh
- = (struct elf_i386_link_hash_entry *) h;
- tls_get_addr = eh->tls_get_addr == 1;
- if (eh->tls_get_addr > 1)
- {
- /* Use strncmp to check ___tls_get_addr since
- ___tls_get_addr may be versioned. */
- if (strncmp (h->root.root.string, "___tls_get_addr", 15)
- == 0)
- {
- eh->tls_get_addr = 1;
- tls_get_addr = TRUE;
- }
- else
- eh->tls_get_addr = 0;
- }
- }
-
- if (!tls_get_addr)
+ if (h == NULL
+ || !((struct elf_i386_link_hash_entry *) h)->tls_get_addr)
return FALSE;
else if (indirect_call)
return (ELF32_R_TYPE (rel[1].r_info) == R_386_GOT32X);
@@ -1863,7 +1841,7 @@ convert_branch:
modrm = 0xe8;
/* To support TLS optimization, always use addr32 prefix
for "call *___tls_get_addr@GOT(%reg)". */
- if (eh && eh->tls_get_addr == 1)
+ if (eh && eh->tls_get_addr)
{
nop = 0x67;
nop_offset = irel->r_offset - 2;
@@ -7148,6 +7126,23 @@ error_alignment:
return pbfd;
}
+static bfd_boolean
+elf_i386_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
+{
+ if (!bfd_link_relocatable (info))
+ {
+ /* Check for ___tls_get_addr reference. */
+ struct elf_link_hash_entry *h;
+ h = elf_link_hash_lookup (elf_hash_table (info), "___tls_get_addr",
+ FALSE, FALSE, FALSE);
+ if (h != NULL)
+ ((struct elf_i386_link_hash_entry *) h)->tls_get_addr = 1;
+ }
+
+ /* Invoke the regular ELF backend linker to do all the work. */
+ return _bfd_elf_link_check_relocs (abfd, info);
+}
+
#define TARGET_LITTLE_SYM i386_elf32_vec
#define TARGET_LITTLE_NAME "elf32-i386"
#define ELF_ARCH bfd_arch_i386
@@ -7178,6 +7173,7 @@ error_alignment:
#define bfd_elf32_bfd_reloc_type_lookup elf_i386_reloc_type_lookup
#define bfd_elf32_bfd_reloc_name_lookup elf_i386_reloc_name_lookup
#define bfd_elf32_get_synthetic_symtab elf_i386_get_synthetic_symtab
+#define bfd_elf32_bfd_link_check_relocs elf_i386_link_check_relocs
#define elf_backend_adjust_dynamic_symbol elf_i386_adjust_dynamic_symbol
#define elf_backend_relocs_compatible _bfd_elf_relocs_compatible
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 448599eb9b..e5f4681354 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -1101,10 +1101,8 @@ struct elf_x86_64_link_hash_entry
/* 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. */
- unsigned int tls_get_addr : 2;
+ /* TRUE if symbol symbol is __tls_get_addr. */
+ unsigned int tls_get_addr : 1;
/* Reference count of C/C++ function pointer relocations in read-write
section which can be resolved at run-time. */
@@ -1264,7 +1262,7 @@ elf_x86_64_link_hash_newfunc (struct bfd_hash_entry *entry,
eh->has_got_reloc = 0;
eh->has_non_got_reloc = 0;
eh->no_finish_dynamic_symbol = 0;
- eh->tls_get_addr = 2;
+ eh->tls_get_addr = 0;
eh->func_pointer_refcount = 0;
eh->plt_second.offset = (bfd_vma) -1;
eh->plt_got.offset = (bfd_vma) -1;
@@ -1527,7 +1525,7 @@ elf_x86_64_check_tls_transition (bfd *abfd,
bfd_vma offset;
struct elf_x86_64_link_hash_table *htab;
bfd_byte *call;
- bfd_boolean indirect_call, tls_get_addr;
+ bfd_boolean indirect_call;
htab = elf_x86_64_hash_table (info);
offset = rel->r_offset;
@@ -1667,29 +1665,9 @@ elf_x86_64_check_tls_transition (bfd *abfd,
if (r_symndx < symtab_hdr->sh_info)
return FALSE;
- tls_get_addr = FALSE;
h = sym_hashes[r_symndx - symtab_hdr->sh_info];
- if (h != NULL && h->root.root.string != NULL)
- {
- struct elf_x86_64_link_hash_entry *eh
- = (struct elf_x86_64_link_hash_entry *) h;
- tls_get_addr = eh->tls_get_addr == 1;
- if (eh->tls_get_addr > 1)
- {
- /* Use strncmp to check __tls_get_addr since
- __tls_get_addr may be versioned. */
- if (strncmp (h->root.root.string, "__tls_get_addr", 14)
- == 0)
- {
- eh->tls_get_addr = 1;
- tls_get_addr = TRUE;
- }
- else
- eh->tls_get_addr = 0;
- }
- }
-
- if (!tls_get_addr)
+ if (h == NULL
+ || !((struct elf_x86_64_link_hash_entry *) h)->tls_get_addr)
return FALSE;
else if (largepic)
return ELF32_R_TYPE (rel[1].r_info) == R_X86_64_PLTOFF64;
@@ -2253,7 +2231,7 @@ convert:
modrm = 0xe8;
/* To support TLS optimization, always use addr32 prefix for
"call *__tls_get_addr@GOTPCREL(%rip)". */
- if (eh && eh->tls_get_addr == 1)
+ if (eh && eh->tls_get_addr)
{
nop = 0x67;
nop_offset = irel->r_offset - 2;
@@ -7715,6 +7693,23 @@ error_alignment:
return pbfd;
}
+static bfd_boolean
+elf_x86_64_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
+{
+ if (!bfd_link_relocatable (info))
+ {
+ /* Check for __tls_get_addr reference. */
+ struct elf_link_hash_entry *h;
+ h = elf_link_hash_lookup (elf_hash_table (info), "__tls_get_addr",
+ FALSE, FALSE, FALSE);
+ if (h != NULL)
+ ((struct elf_x86_64_link_hash_entry *) h)->tls_get_addr = 1;
+ }
+
+ /* Invoke the regular ELF backend linker to do all the work. */
+ return _bfd_elf_link_check_relocs (abfd, info);
+}
+
static const struct bfd_elf_special_section
elf_x86_64_special_sections[]=
{
@@ -7779,6 +7774,7 @@ elf_x86_64_special_sections[]=
#define elf_backend_object_p elf64_x86_64_elf_object_p
#define bfd_elf64_mkobject elf_x86_64_mkobject
#define bfd_elf64_get_synthetic_symtab elf_x86_64_get_synthetic_symtab
+#define bfd_elf64_bfd_link_check_relocs elf_x86_64_link_check_relocs
#define elf_backend_section_from_shdr \
elf_x86_64_section_from_shdr
@@ -8078,6 +8074,8 @@ elf32_x86_64_nacl_elf_object_p (bfd *abfd)
elf_x86_64_mkobject
#define bfd_elf32_get_synthetic_symtab \
elf_x86_64_get_synthetic_symtab
+#define bfd_elf32_bfd_link_check_relocs \
+ elf_x86_64_link_check_relocs
#undef elf_backend_object_p
#define elf_backend_object_p \
--
2.13.3
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