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authorH.J. Lu <hjl.tools@gmail.com>2016-05-05 04:13:47 -0700
committerH.J. Lu <hjl.tools@gmail.com>2016-05-05 04:14:00 -0700
commitc175a65796a6f1d6a69ed0d7e3bce6f048c8e983 (patch)
tree7275e19d973665cc23e75de3f7b6e174eaa348f5 /bfd/elf32-i386.c
parentbedfd056d4d58a3ebaf8d396c8453f0d0468576f (diff)
downloadbinutils-gdb-c175a65796a6f1d6a69ed0d7e3bce6f048c8e983.tar.gz
Extract convert_load_reloc from x86 convert_load
* elf32-i386.c (elf_i386_convert_load): Extract the GOT load conversion to ... (elf_i386_convert_load_reloc): This. New function. * elf64-x86-64.c (elf_x86_64_convert_load): Extract the GOT load conversion to ... (elf_x86_64_convert_load_reloc): This. New function.
Diffstat (limited to 'bfd/elf32-i386.c')
-rw-r--r--bfd/elf32-i386.c554
1 files changed, 280 insertions, 274 deletions
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index ff0f140f388..483146b1a5a 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -1499,6 +1499,255 @@ elf_i386_tls_transition (struct bfd_link_info *info, bfd *abfd,
return TRUE;
}
+/* With the local symbol, foo, we convert
+ mov foo@GOT[(%reg1)], %reg2
+ to
+ lea foo[@GOTOFF(%reg1)], %reg2
+ and convert
+ call/jmp *foo@GOT[(%reg)]
+ to
+ nop call foo/jmp foo nop
+ When PIC is false, convert
+ test %reg1, foo@GOT[(%reg2)]
+ to
+ test $foo, %reg1
+ and convert
+ binop foo@GOT[(%reg1)], %reg2
+ to
+ binop $foo, %reg2
+ where binop is one of adc, add, and, cmp, or, sbb, sub, xor
+ instructions. */
+
+static
+bfd_boolean
+elf_i386_convert_load_reloc (bfd *abfd, Elf_Internal_Shdr *symtab_hdr,
+ bfd_byte *contents,
+ Elf_Internal_Rela *irel,
+ struct elf_link_hash_entry *h,
+ bfd_boolean *converted,
+ struct bfd_link_info *link_info)
+{
+ struct elf_i386_link_hash_table *htab;
+ unsigned int opcode;
+ unsigned int modrm;
+ bfd_boolean baseless;
+ Elf_Internal_Sym *isym;
+ unsigned int addend;
+ unsigned int nop;
+ bfd_vma nop_offset;
+ bfd_boolean is_pic;
+ bfd_boolean to_reloc_32;
+ unsigned int r_type;
+ unsigned int r_symndx;
+ bfd_vma roff = irel->r_offset;
+
+ if (roff < 2)
+ return TRUE;
+
+ /* Addend for R_386_GOT32 and R_386_GOT32X relocations must be 0. */
+ addend = bfd_get_32 (abfd, contents + roff);
+ if (addend != 0)
+ return TRUE;
+
+ htab = elf_i386_hash_table (link_info);
+ is_pic = bfd_link_pic (link_info);
+
+ r_type = ELF32_R_TYPE (irel->r_info);
+ r_symndx = ELF32_R_SYM (irel->r_info);
+
+ modrm = bfd_get_8 (abfd, contents + roff - 1);
+ baseless = (modrm & 0xc7) == 0x5;
+
+ if (r_type == R_386_GOT32X && baseless && is_pic)
+ {
+ /* For PIC, disallow R_386_GOT32X without a base register
+ since we don't know what the GOT base is. Allow
+ R_386_GOT32 for existing object files. */
+ const char *name;
+
+ if (h == NULL)
+ {
+ isym = bfd_sym_from_r_symndx (&htab->sym_cache, abfd,
+ r_symndx);
+ name = bfd_elf_sym_name (abfd, symtab_hdr, isym, NULL);
+ }
+ else
+ name = h->root.root.string;
+
+ (*_bfd_error_handler)
+ (_("%B: direct GOT relocation R_386_GOT32X against `%s' without base register can not be used when making a shared object"),
+ abfd, name);
+ return FALSE;
+ }
+
+ opcode = bfd_get_8 (abfd, contents + roff - 2);
+
+ /* Convert mov to lea since it has been done for a while. */
+ if (opcode != 0x8b)
+ {
+ /* Only convert R_386_GOT32X relocation for call, jmp or
+ one of adc, add, and, cmp, or, sbb, sub, test, xor
+ instructions. */
+ if (r_type != R_386_GOT32X)
+ return TRUE;
+ }
+
+ /* Convert to R_386_32 if PIC is false or there is no base
+ register. */
+ to_reloc_32 = !is_pic || baseless;
+
+ /* Try to convert R_386_GOT32 and R_386_GOT32X. Get the symbol
+ referred to by the reloc. */
+ if (h == NULL)
+ {
+ if (opcode == 0x0ff)
+ /* Convert "call/jmp *foo@GOT[(%reg)]". */
+ goto convert_branch;
+ else
+ /* Convert "mov foo@GOT[(%reg1)], %reg2",
+ "test %reg1, foo@GOT(%reg2)" and
+ "binop foo@GOT[(%reg1)], %reg2". */
+ goto convert_load;
+ }
+
+ /* Undefined weak symbol is only bound locally in executable
+ and its reference is resolved as 0. */
+ if (UNDEFINED_WEAK_RESOLVED_TO_ZERO (link_info, TRUE,
+ elf_i386_hash_entry (h)))
+ {
+ if (opcode == 0xff)
+ {
+ /* No direct branch to 0 for PIC. */
+ if (is_pic)
+ return TRUE;
+ else
+ goto convert_branch;
+ }
+ else
+ {
+ /* We can convert load of address 0 to R_386_32. */
+ to_reloc_32 = TRUE;
+ goto convert_load;
+ }
+ }
+
+ if (opcode == 0xff)
+ {
+ /* We have "call/jmp *foo@GOT[(%reg)]". */
+ if ((h->root.type == bfd_link_hash_defined
+ || h->root.type == bfd_link_hash_defweak)
+ && SYMBOL_REFERENCES_LOCAL (link_info, h))
+ {
+ /* The function is locally defined. */
+convert_branch:
+ /* Convert R_386_GOT32X to R_386_PC32. */
+ if (modrm == 0x15 || (modrm & 0xf8) == 0x90)
+ {
+ /* Convert to "nop call foo". ADDR_PREFIX_OPCODE
+ is a nop prefix. */
+ modrm = 0xe8;
+ nop = link_info->call_nop_byte;
+ if (link_info->call_nop_as_suffix)
+ {
+ nop_offset = roff + 3;
+ irel->r_offset -= 1;
+ }
+ else
+ nop_offset = roff - 2;
+ }
+ else
+ {
+ /* Convert to "jmp foo nop". */
+ modrm = 0xe9;
+ nop = NOP_OPCODE;
+ nop_offset = roff + 3;
+ irel->r_offset -= 1;
+ }
+
+ bfd_put_8 (abfd, nop, contents + nop_offset);
+ bfd_put_8 (abfd, modrm, contents + irel->r_offset - 1);
+ /* When converting to PC-relative relocation, we
+ need to adjust addend by -4. */
+ bfd_put_32 (abfd, -4, contents + irel->r_offset);
+ irel->r_info = ELF32_R_INFO (r_symndx, R_386_PC32);
+
+ *converted = TRUE;
+ }
+ }
+ else
+ {
+ /* We have "mov foo@GOT[(%re1g)], %reg2",
+ "test %reg1, foo@GOT(%reg2)" and
+ "binop foo@GOT[(%reg1)], %reg2".
+
+ Avoid optimizing _DYNAMIC since ld.so may use its
+ link-time address. */
+ if (h == htab->elf.hdynamic)
+ return TRUE;
+
+ /* def_regular is set by an assignment in a linker script in
+ bfd_elf_record_link_assignment. */
+ if ((h->def_regular
+ || h->root.type == bfd_link_hash_defined
+ || h->root.type == bfd_link_hash_defweak)
+ && SYMBOL_REFERENCES_LOCAL (link_info, h))
+ {
+convert_load:
+ if (opcode == 0x8b)
+ {
+ if (to_reloc_32)
+ {
+ /* Convert "mov foo@GOT[(%reg1)], %reg2" to
+ "mov $foo, %reg2" with R_386_32. */
+ r_type = R_386_32;
+ modrm = 0xc0 | (modrm & 0x38) >> 3;
+ bfd_put_8 (abfd, modrm, contents + roff - 1);
+ opcode = 0xc7;
+ }
+ else
+ {
+ /* Convert "mov foo@GOT(%reg1), %reg2" to
+ "lea foo@GOTOFF(%reg1), %reg2". */
+ r_type = R_386_GOTOFF;
+ opcode = 0x8d;
+ }
+ }
+ else
+ {
+ /* Only R_386_32 is supported. */
+ if (!to_reloc_32)
+ return TRUE;
+
+ if (opcode == 0x85)
+ {
+ /* Convert "test %reg1, foo@GOT(%reg2)" to
+ "test $foo, %reg1". */
+ modrm = 0xc0 | (modrm & 0x38) >> 3;
+ opcode = 0xf7;
+ }
+ else
+ {
+ /* Convert "binop foo@GOT(%reg1), %reg2" to
+ "binop $foo, %reg2". */
+ modrm = (0xc0
+ | (modrm & 0x38) >> 3
+ | (opcode & 0x3c));
+ opcode = 0x81;
+ }
+ bfd_put_8 (abfd, modrm, contents + roff - 1);
+ r_type = R_386_32;
+ }
+
+ bfd_put_8 (abfd, opcode, contents + roff - 2);
+ irel->r_info = ELF32_R_INFO (r_symndx, r_type);
+
+ *converted = TRUE;
+ }
+ }
+
+ return TRUE;
+}
+
/* Rename some of the generic section flags to better document how they
are used here. */
#define need_convert_load sec_flg0
@@ -2718,37 +2967,18 @@ elf_i386_readonly_dynrelocs (struct elf_link_hash_entry *h, void *inf)
return TRUE;
}
-/* With the local symbol, foo, we convert
- mov foo@GOT[(%reg1)], %reg2
- to
- lea foo[@GOTOFF(%reg1)], %reg2
- and convert
- call/jmp *foo@GOT[(%reg)]
- to
- nop call foo/jmp foo nop
- When PIC is false, convert
- test %reg1, foo@GOT[(%reg2)]
- to
- test $foo, %reg1
- and convert
- binop foo@GOT[(%reg1)], %reg2
- to
- binop $foo, %reg2
- where binop is one of adc, add, and, cmp, or, sbb, sub, xor
- instructions. */
+/* Convert load via the GOT slot to load immediate. */
static bfd_boolean
elf_i386_convert_load (bfd *abfd, asection *sec,
struct bfd_link_info *link_info)
{
+ struct elf_i386_link_hash_table *htab;
Elf_Internal_Shdr *symtab_hdr;
Elf_Internal_Rela *internal_relocs;
Elf_Internal_Rela *irel, *irelend;
bfd_byte *contents;
- struct elf_i386_link_hash_table *htab;
- bfd_boolean changed_contents;
- bfd_boolean changed_relocs;
- bfd_boolean is_pic;
+ bfd_boolean changed;
bfd_signed_vma *local_got_refcounts;
/* Don't even try to convert non-ELF outputs. */
@@ -2770,13 +3000,10 @@ elf_i386_convert_load (bfd *abfd, asection *sec,
if (internal_relocs == NULL)
return FALSE;
+ changed = FALSE;
htab = elf_i386_hash_table (link_info);
- changed_contents = FALSE;
- changed_relocs = FALSE;
local_got_refcounts = elf_local_got_refcounts (abfd);
- is_pic = bfd_link_pic (link_info);
-
/* Get the section contents. */
if (elf_section_data (sec)->this_hdr.contents != NULL)
contents = elf_section_data (sec)->this_hdr.contents;
@@ -2790,269 +3017,48 @@ elf_i386_convert_load (bfd *abfd, asection *sec,
for (irel = internal_relocs; irel < irelend; irel++)
{
unsigned int r_type = ELF32_R_TYPE (irel->r_info);
- unsigned int r_symndx = ELF32_R_SYM (irel->r_info);
- unsigned int indx;
+ unsigned int r_symndx;
struct elf_link_hash_entry *h;
- unsigned int opcode;
- unsigned int modrm;
- bfd_vma roff;
- bfd_boolean baseless;
- Elf_Internal_Sym *isym;
- unsigned int addend;
- unsigned int nop;
- bfd_vma nop_offset;
- bfd_boolean to_reloc_32;
+ bfd_boolean converted;
if (r_type != R_386_GOT32 && r_type != R_386_GOT32X)
continue;
- roff = irel->r_offset;
- if (roff < 2)
- continue;
-
- /* Addend for R_386_GOT32 and R_386_GOT32X relocations must be 0. */
- addend = bfd_get_32 (abfd, contents + roff);
- if (addend != 0)
- continue;
-
- modrm = bfd_get_8 (abfd, contents + roff - 1);
- baseless = (modrm & 0xc7) == 0x5;
-
- if (r_type == R_386_GOT32X && baseless && is_pic)
- {
- /* For PIC, disallow R_386_GOT32X without a base register
- since we don't know what the GOT base is. Allow
- R_386_GOT32 for existing object files. */
- const char *name;
-
- if (r_symndx < symtab_hdr->sh_info)
- {
- isym = bfd_sym_from_r_symndx (&htab->sym_cache, abfd,
- r_symndx);
- name = bfd_elf_sym_name (abfd, symtab_hdr, isym, NULL);
- }
- else
- {
- indx = r_symndx - symtab_hdr->sh_info;
- h = elf_sym_hashes (abfd)[indx];
- BFD_ASSERT (h != NULL);
- name = h->root.root.string;
- }
-
- (*_bfd_error_handler)
- (_("%B: direct GOT relocation R_386_GOT32X against `%s' without base register can not be used when making a shared object"),
- abfd, name);
- goto error_return;
- }
-
- opcode = bfd_get_8 (abfd, contents + roff - 2);
-
- /* Convert mov to lea since it has been done for a while. */
- if (opcode != 0x8b)
- {
- /* Only convert R_386_GOT32X relocation for call, jmp or
- one of adc, add, and, cmp, or, sbb, sub, test, xor
- instructions. */
- if (r_type != R_386_GOT32X)
- continue;
- }
-
- /* Convert to R_386_32 if PIC is false or there is no base
- register. */
- to_reloc_32 = !is_pic || baseless;
-
- /* Try to convert R_386_GOT32 and R_386_GOT32X. Get the symbol
- referred to by the reloc. */
+ r_symndx = ELF32_R_SYM (irel->r_info);
if (r_symndx < symtab_hdr->sh_info)
+ h = elf_i386_get_local_sym_hash (htab, sec->owner,
+ (const Elf_Internal_Rela *) irel,
+ FALSE);
+ else
{
- isym = bfd_sym_from_r_symndx (&htab->sym_cache,
- abfd, r_symndx);
-
- /* STT_GNU_IFUNC must keep GOT32 relocations. */
- if (ELF_ST_TYPE (isym->st_info) == STT_GNU_IFUNC)
- continue;
-
- h = NULL;
- if (opcode == 0x0ff)
- /* Convert "call/jmp *foo@GOT[(%reg)]". */
- goto convert_branch;
- else
- /* Convert "mov foo@GOT[(%reg1)], %reg2",
- "test %reg1, foo@GOT(%reg2)" and
- "binop foo@GOT[(%reg1)], %reg2". */
- goto convert_load;
+ h = elf_sym_hashes (abfd)[r_symndx - symtab_hdr->sh_info];
+ while (h->root.type == bfd_link_hash_indirect
+ || h->root.type == bfd_link_hash_warning)
+ h = (struct elf_link_hash_entry *) h->root.u.i.link;
}
- indx = r_symndx - symtab_hdr->sh_info;
- h = elf_sym_hashes (abfd)[indx];
- BFD_ASSERT (h != NULL);
-
- while (h->root.type == bfd_link_hash_indirect
- || h->root.type == bfd_link_hash_warning)
- h = (struct elf_link_hash_entry *) h->root.u.i.link;
-
/* STT_GNU_IFUNC must keep GOT32 relocations. */
- if (h->type == STT_GNU_IFUNC)
+ if (h != NULL && h->type == STT_GNU_IFUNC)
continue;
- /* Undefined weak symbol is only bound locally in executable
- and its reference is resolved as 0. */
- if (UNDEFINED_WEAK_RESOLVED_TO_ZERO (link_info, TRUE,
- elf_i386_hash_entry (h)))
- {
- if (opcode == 0xff)
- {
- /* No direct branch to 0 for PIC. */
- if (is_pic)
- continue;
- else
- goto convert_branch;
- }
- else
- {
- /* We can convert load of address 0 to R_386_32. */
- to_reloc_32 = TRUE;
- goto convert_load;
- }
- }
+ converted = FALSE;
+ if (!elf_i386_convert_load_reloc (abfd, symtab_hdr, contents,
+ irel, h, &converted, link_info))
+ goto error_return;
- if (opcode == 0xff)
+ if (converted)
{
- /* We have "call/jmp *foo@GOT[(%reg)]". */
- if ((h->root.type == bfd_link_hash_defined
- || h->root.type == bfd_link_hash_defweak)
- && SYMBOL_REFERENCES_LOCAL (link_info, h))
+ changed = converted;
+ if (h)
{
- /* The function is locally defined. */
-convert_branch:
- /* Convert R_386_GOT32X to R_386_PC32. */
- if (modrm == 0x15 || (modrm & 0xf8) == 0x90)
- {
- /* Convert to "nop call foo". ADDR_PREFIX_OPCODE
- is a nop prefix. */
- modrm = 0xe8;
- nop = link_info->call_nop_byte;
- if (link_info->call_nop_as_suffix)
- {
- nop_offset = roff + 3;
- irel->r_offset -= 1;
- }
- else
- nop_offset = roff - 2;
- }
- else
- {
- /* Convert to "jmp foo nop". */
- modrm = 0xe9;
- nop = NOP_OPCODE;
- nop_offset = roff + 3;
- irel->r_offset -= 1;
- }
-
- bfd_put_8 (abfd, nop, contents + nop_offset);
- bfd_put_8 (abfd, modrm, contents + irel->r_offset - 1);
- /* When converting to PC-relative relocation, we
- need to adjust addend by -4. */
- bfd_put_32 (abfd, -4, contents + irel->r_offset);
- irel->r_info = ELF32_R_INFO (r_symndx, R_386_PC32);
-
- if (h)
- {
- if (h->got.refcount > 0)
- h->got.refcount -= 1;
- }
- else
- {
- if (local_got_refcounts != NULL
- && local_got_refcounts[r_symndx] > 0)
- local_got_refcounts[r_symndx] -= 1;
- }
-
- changed_contents = TRUE;
- changed_relocs = TRUE;
+ if (h->got.refcount > 0)
+ h->got.refcount -= 1;
}
- }
- else
- {
- /* We have "mov foo@GOT[(%re1g)], %reg2",
- "test %reg1, foo@GOT(%reg2)" and
- "binop foo@GOT[(%reg1)], %reg2".
-
- Avoid optimizing _DYNAMIC since ld.so may use its
- link-time address. */
- if (h == htab->elf.hdynamic)
- continue;
-
- /* def_regular is set by an assignment in a linker script in
- bfd_elf_record_link_assignment. */
- if ((h->def_regular
- || h->root.type == bfd_link_hash_defined
- || h->root.type == bfd_link_hash_defweak)
- && SYMBOL_REFERENCES_LOCAL (link_info, h))
+ else
{
-convert_load:
- if (opcode == 0x8b)
- {
- if (to_reloc_32)
- {
- /* Convert "mov foo@GOT[(%reg1)], %reg2" to
- "mov $foo, %reg2" with R_386_32. */
- r_type = R_386_32;
- modrm = 0xc0 | (modrm & 0x38) >> 3;
- bfd_put_8 (abfd, modrm, contents + roff - 1);
- opcode = 0xc7;
- }
- else
- {
- /* Convert "mov foo@GOT(%reg1), %reg2" to
- "lea foo@GOTOFF(%reg1), %reg2". */
- r_type = R_386_GOTOFF;
- opcode = 0x8d;
- }
- }
- else
- {
- /* Only R_386_32 is supported. */
- if (!to_reloc_32)
- continue;
-
- if (opcode == 0x85)
- {
- /* Convert "test %reg1, foo@GOT(%reg2)" to
- "test $foo, %reg1". */
- modrm = 0xc0 | (modrm & 0x38) >> 3;
- opcode = 0xf7;
- }
- else
- {
- /* Convert "binop foo@GOT(%reg1), %reg2" to
- "binop $foo, %reg2". */
- modrm = (0xc0
- | (modrm & 0x38) >> 3
- | (opcode & 0x3c));
- opcode = 0x81;
- }
- bfd_put_8 (abfd, modrm, contents + roff - 1);
- r_type = R_386_32;
- }
-
- bfd_put_8 (abfd, opcode, contents + roff - 2);
- irel->r_info = ELF32_R_INFO (r_symndx, r_type);
-
- if (h)
- {
- if (h->got.refcount > 0)
- h->got.refcount -= 1;
- }
- else
- {
- if (local_got_refcounts != NULL
- && local_got_refcounts[r_symndx] > 0)
- local_got_refcounts[r_symndx] -= 1;
- }
-
- changed_contents = TRUE;
- changed_relocs = TRUE;
+ if (local_got_refcounts != NULL
+ && local_got_refcounts[r_symndx] > 0)
+ local_got_refcounts[r_symndx] -= 1;
}
}
}
@@ -3060,7 +3066,7 @@ convert_load:
if (contents != NULL
&& elf_section_data (sec)->this_hdr.contents != contents)
{
- if (!changed_contents && !link_info->keep_memory)
+ if (!changed && !link_info->keep_memory)
free (contents);
else
{
@@ -3071,7 +3077,7 @@ convert_load:
if (elf_section_data (sec)->relocs != internal_relocs)
{
- if (!changed_relocs)
+ if (!changed)
free (internal_relocs);
else
elf_section_data (sec)->relocs = internal_relocs;