diff options
| -rw-r--r-- | bfd/elf32-i386.c | 554 | ||||
| -rw-r--r-- | bfd/elf64-x86-64.c | 821 |
2 files changed, 705 insertions, 670 deletions
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c index ff0f140..483146b 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; diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c index 6c55a60..0bcd59d 100644 --- a/bfd/elf64-x86-64.c +++ b/bfd/elf64-x86-64.c @@ -1634,6 +1634,401 @@ elf_x86_64_need_pic (bfd *input_bfd, asection *sec, return FALSE; } +/* With the local symbol, foo, we convert + mov foo@GOTPCREL(%rip), %reg + to + lea foo(%rip), %reg + and convert + call/jmp *foo@GOTPCREL(%rip) + to + nop call foo/jmp foo nop + When PIC is false, convert + test %reg, foo@GOTPCREL(%rip) + to + test $foo, %reg + and convert + binop foo@GOTPCREL(%rip), %reg + to + binop $foo, %reg + where binop is one of adc, add, and, cmp, or, sbb, sub, xor + instructions. */ + +static bfd_boolean +elf_x86_64_convert_load_reloc (bfd *abfd, asection *sec, + bfd_byte *contents, + Elf_Internal_Rela *irel, + struct elf_link_hash_entry *h, + bfd_boolean *converted, + struct bfd_link_info *link_info) +{ + struct elf_x86_64_link_hash_table *htab; + bfd_boolean is_pic; + bfd_boolean require_reloc_pc32; + bfd_boolean relocx; + bfd_boolean to_reloc_pc32; + asection *tsec; + char symtype; + bfd_signed_vma raddend; + unsigned int opcode; + unsigned int modrm; + unsigned int r_type = ELF32_R_TYPE (irel->r_info); + unsigned int r_symndx; + bfd_vma toff; + bfd_vma roff = irel->r_offset; + + if (roff < (r_type == R_X86_64_REX_GOTPCRELX ? 3 : 2)) + return TRUE; + + raddend = irel->r_addend; + /* Addend for 32-bit PC-relative relocation must be -4. */ + if (raddend != -4) + return TRUE; + + htab = elf_x86_64_hash_table (link_info); + is_pic = bfd_link_pic (link_info); + + relocx = (r_type == R_X86_64_GOTPCRELX + || r_type == R_X86_64_REX_GOTPCRELX); + + /* TRUE if we can convert only to R_X86_64_PC32. Enable it for + --no-relax. */ + require_reloc_pc32 + = link_info->disable_target_specific_optimizations > 1; + + r_symndx = htab->r_sym (irel->r_info); + + 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_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX + for call, jmp or one of adc, add, and, cmp, or, sbb, sub, + test, xor instructions. */ + if (!relocx) + return TRUE; + } + + /* We convert only to R_X86_64_PC32: + 1. Branch. + 2. R_X86_64_GOTPCREL since we can't modify REX byte. + 3. require_reloc_pc32 is true. + 4. PIC. + */ + to_reloc_pc32 = (opcode == 0xff + || !relocx + || require_reloc_pc32 + || is_pic); + + /* Get the symbol referred to by the reloc. */ + if (h == NULL) + { + Elf_Internal_Sym *isym + = bfd_sym_from_r_symndx (&htab->sym_cache, abfd, r_symndx); + + /* Skip relocation against undefined symbols. */ + if (isym->st_shndx == SHN_UNDEF) + return TRUE; + + symtype = ELF_ST_TYPE (isym->st_info); + + if (isym->st_shndx == SHN_ABS) + tsec = bfd_abs_section_ptr; + else if (isym->st_shndx == SHN_COMMON) + tsec = bfd_com_section_ptr; + else if (isym->st_shndx == SHN_X86_64_LCOMMON) + tsec = &_bfd_elf_large_com_section; + else + tsec = bfd_section_from_elf_index (abfd, isym->st_shndx); + + toff = isym->st_value; + } + else + { + /* Undefined weak symbol is only bound locally in executable + and its reference is resolved as 0 without relocation + overflow. We can only perform this optimization for + GOTPCRELX relocations since we need to modify REX byte. + It is OK convert mov with R_X86_64_GOTPCREL to + R_X86_64_PC32. */ + if ((relocx || opcode == 0x8b) + && UNDEFINED_WEAK_RESOLVED_TO_ZERO (link_info, + TRUE, + elf_x86_64_hash_entry (h))) + { + if (opcode == 0xff) + { + /* Skip for branch instructions since R_X86_64_PC32 + may overflow. */ + if (require_reloc_pc32) + return TRUE; + } + else if (relocx) + { + /* For non-branch instructions, we can convert to + R_X86_64_32/R_X86_64_32S since we know if there + is a REX byte. */ + to_reloc_pc32 = FALSE; + } + + /* Since we don't know the current PC when PIC is true, + we can't convert to R_X86_64_PC32. */ + if (to_reloc_pc32 && is_pic) + return TRUE; + + goto convert; + } + /* Avoid optimizing GOTPCREL relocations againt _DYNAMIC since + ld.so may use its link-time address. */ + else if ((h->def_regular + || h->root.type == bfd_link_hash_defined + || h->root.type == bfd_link_hash_defweak) + && h != htab->elf.hdynamic + && SYMBOL_REFERENCES_LOCAL (link_info, h)) + { + /* bfd_link_hash_new or bfd_link_hash_undefined 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_new + || h->root.type == bfd_link_hash_undefined)) + { + /* Skip since R_X86_64_32/R_X86_64_32S may overflow. */ + if (require_reloc_pc32) + return TRUE; + goto convert; + } + tsec = h->root.u.def.section; + toff = h->root.u.def.value; + symtype = h->type; + } + else + return TRUE; + } + + /* We can only estimate relocation overflow for R_X86_64_PC32. */ + if (!to_reloc_pc32) + goto convert; + + if (tsec->sec_info_type == SEC_INFO_TYPE_MERGE) + { + /* At this stage in linking, no SEC_MERGE symbol has been + adjusted, so all references to such symbols need to be + passed through _bfd_merged_section_offset. (Later, in + relocate_section, all SEC_MERGE symbols *except* for + section symbols have been adjusted.) + + gas may reduce relocations against symbols in SEC_MERGE + sections to a relocation against the section symbol when + the original addend was zero. When the reloc is against + a section symbol we should include the addend in the + offset passed to _bfd_merged_section_offset, since the + location of interest is the original symbol. On the + other hand, an access to "sym+addend" where "sym" is not + a section symbol should not include the addend; Such an + access is presumed to be an offset from "sym"; The + location of interest is just "sym". */ + if (symtype == STT_SECTION) + toff += raddend; + + toff = _bfd_merged_section_offset (abfd, &tsec, + elf_section_data (tsec)->sec_info, + toff); + + if (symtype != STT_SECTION) + toff += raddend; + } + else + toff += raddend; + + /* Don't convert if R_X86_64_PC32 relocation overflows. */ + if (tsec->output_section == sec->output_section) + { + if ((toff - roff + 0x80000000) > 0xffffffff) + return TRUE; + } + else + { + bfd_signed_vma distance; + + /* At this point, we don't know the load addresses of TSEC + section nor SEC section. We estimate the distrance between + SEC and TSEC. We store the estimated distances in the + compressed_size field of the output section, which is only + used to decompress the compressed input section. */ + if (sec->output_section->compressed_size == 0) + { + asection *asect; + bfd_size_type size = 0; + for (asect = link_info->output_bfd->sections; + asect != NULL; + asect = asect->next) + /* Skip debug sections since compressed_size is used to + compress debug sections. */ + if ((asect->flags & SEC_DEBUGGING) == 0) + { + asection *i; + for (i = asect->map_head.s; + i != NULL; + i = i->map_head.s) + { + size = align_power (size, i->alignment_power); + size += i->size; + } + asect->compressed_size = size; + } + } + + /* Don't convert GOTPCREL relocations if TSEC isn't placed + after SEC. */ + distance = (tsec->output_section->compressed_size + - sec->output_section->compressed_size); + if (distance < 0) + return TRUE; + + /* Take PT_GNU_RELRO segment into account by adding + maxpagesize. */ + if ((toff + distance + get_elf_backend_data (abfd)->maxpagesize + - roff + 0x80000000) > 0xffffffff) + return TRUE; + } + +convert: + if (opcode == 0xff) + { + /* We have "call/jmp *foo@GOTPCREL(%rip)". */ + unsigned int nop; + unsigned int disp; + bfd_vma nop_offset; + + /* Convert R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX to + R_X86_64_PC32. */ + modrm = bfd_get_8 (abfd, contents + roff - 1); + if (modrm == 0x25) + { + /* Convert to "jmp foo nop". */ + modrm = 0xe9; + nop = NOP_OPCODE; + nop_offset = irel->r_offset + 3; + disp = bfd_get_32 (abfd, contents + irel->r_offset); + irel->r_offset -= 1; + bfd_put_32 (abfd, disp, contents + irel->r_offset); + } + else + { + /* 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 = irel->r_offset + 3; + disp = bfd_get_32 (abfd, contents + irel->r_offset); + irel->r_offset -= 1; + bfd_put_32 (abfd, disp, contents + irel->r_offset); + } + else + nop_offset = irel->r_offset - 2; + } + bfd_put_8 (abfd, nop, contents + nop_offset); + bfd_put_8 (abfd, modrm, contents + irel->r_offset - 1); + r_type = R_X86_64_PC32; + } + else + { + unsigned int rex; + unsigned int rex_mask = REX_R; + + if (r_type == R_X86_64_REX_GOTPCRELX) + rex = bfd_get_8 (abfd, contents + roff - 3); + else + rex = 0; + + if (opcode == 0x8b) + { + if (to_reloc_pc32) + { + /* Convert "mov foo@GOTPCREL(%rip), %reg" to + "lea foo(%rip), %reg". */ + opcode = 0x8d; + r_type = R_X86_64_PC32; + } + else + { + /* Convert "mov foo@GOTPCREL(%rip), %reg" to + "mov $foo, %reg". */ + opcode = 0xc7; + modrm = bfd_get_8 (abfd, contents + roff - 1); + modrm = 0xc0 | (modrm & 0x38) >> 3; + if ((rex & REX_W) != 0 + && ABI_64_P (link_info->output_bfd)) + { + /* Keep the REX_W bit in REX byte for LP64. */ + r_type = R_X86_64_32S; + goto rewrite_modrm_rex; + } + else + { + /* If the REX_W bit in REX byte isn't needed, + use R_X86_64_32 and clear the W bit to avoid + sign-extend imm32 to imm64. */ + r_type = R_X86_64_32; + /* Clear the W bit in REX byte. */ + rex_mask |= REX_W; + goto rewrite_modrm_rex; + } + } + } + else + { + /* R_X86_64_PC32 isn't supported. */ + if (to_reloc_pc32) + return TRUE; + + modrm = bfd_get_8 (abfd, contents + roff - 1); + if (opcode == 0x85) + { + /* Convert "test %reg, foo@GOTPCREL(%rip)" to + "test $foo, %reg". */ + modrm = 0xc0 | (modrm & 0x38) >> 3; + opcode = 0xf7; + } + else + { + /* Convert "binop foo@GOTPCREL(%rip), %reg" to + "binop $foo, %reg". */ + modrm = 0xc0 | (modrm & 0x38) >> 3 | (opcode & 0x3c); + opcode = 0x81; + } + + /* Use R_X86_64_32 with 32-bit operand to avoid relocation + overflow when sign-extending imm32 to imm64. */ + r_type = (rex & REX_W) != 0 ? R_X86_64_32S : R_X86_64_32; + +rewrite_modrm_rex: + bfd_put_8 (abfd, modrm, contents + roff - 1); + + if (rex) + { + /* Move the R bit to the B bit in REX byte. */ + rex = (rex & ~rex_mask) | (rex & REX_R) >> 2; + bfd_put_8 (abfd, rex, contents + roff - 3); + } + + /* No addend for R_X86_64_32/R_X86_64_32S relocations. */ + irel->r_addend = 0; + } + + bfd_put_8 (abfd, opcode, contents + roff - 2); + } + + irel->r_info = htab->r_info (r_symndx, r_type); + + *converted = TRUE; + + return TRUE; +} + /* Look through the relocs for a section during the first phase, and calculate needed space in the global offset table, procedure linkage table, and dynamic reloc sections. */ @@ -2946,24 +3341,7 @@ elf_x86_64_readonly_dynrelocs (struct elf_link_hash_entry *h, return TRUE; } -/* With the local symbol, foo, we convert - mov foo@GOTPCREL(%rip), %reg - to - lea foo(%rip), %reg - and convert - call/jmp *foo@GOTPCREL(%rip) - to - nop call foo/jmp foo nop - When PIC is false, convert - test %reg, foo@GOTPCREL(%rip) - to - test $foo, %reg - and convert - binop foo@GOTPCREL(%rip), %reg - to - binop $foo, %reg - 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_x86_64_convert_load (bfd *abfd, asection *sec, @@ -2974,12 +3352,8 @@ elf_x86_64_convert_load (bfd *abfd, asection *sec, Elf_Internal_Rela *irel, *irelend; bfd_byte *contents; struct elf_x86_64_link_hash_table *htab; - bfd_boolean changed_contents; - bfd_boolean changed_relocs; + bfd_boolean changed; bfd_signed_vma *local_got_refcounts; - bfd_vma maxpagesize; - bfd_boolean is_pic; - bfd_boolean require_reloc_pc32; /* Don't even try to convert non-ELF outputs. */ if (!is_elf_hash_table (link_info->hash)) @@ -3000,11 +3374,9 @@ elf_x86_64_convert_load (bfd *abfd, asection *sec, if (internal_relocs == NULL) return FALSE; + changed = FALSE; htab = elf_x86_64_hash_table (link_info); - changed_contents = FALSE; - changed_relocs = FALSE; local_got_refcounts = elf_local_got_refcounts (abfd); - maxpagesize = get_elf_backend_data (abfd)->maxpagesize; /* Get the section contents. */ if (elf_section_data (sec)->this_hdr.contents != NULL) @@ -3015,405 +3387,62 @@ elf_x86_64_convert_load (bfd *abfd, asection *sec, goto error_return; } - is_pic = bfd_link_pic (link_info); - - /* TRUE if we can convert only to R_X86_64_PC32. Enable it for - --no-relax. */ - require_reloc_pc32 - = link_info->disable_target_specific_optimizations > 1; - irelend = internal_relocs + sec->reloc_count; for (irel = internal_relocs; irel < irelend; irel++) { unsigned int r_type = ELF32_R_TYPE (irel->r_info); - unsigned int r_symndx = htab->r_sym (irel->r_info); - unsigned int indx; + unsigned int r_symndx; struct elf_link_hash_entry *h; - asection *tsec; - char symtype; - bfd_vma toff, roff; - bfd_signed_vma raddend; - unsigned int opcode; - unsigned int modrm; - bfd_boolean relocx; - bfd_boolean to_reloc_pc32; - - relocx = (r_type == R_X86_64_GOTPCRELX - || r_type == R_X86_64_REX_GOTPCRELX); - if (!relocx && r_type != R_X86_64_GOTPCREL) - continue; + bfd_boolean converted; - roff = irel->r_offset; - if (roff < (r_type == R_X86_64_REX_GOTPCRELX ? 3 : 2)) + if (r_type != R_X86_64_GOTPCRELX + && r_type != R_X86_64_REX_GOTPCRELX + && r_type != R_X86_64_GOTPCREL) continue; - raddend = irel->r_addend; - /* Addend for 32-bit PC-relative relocation must be -4. */ - if (raddend != -4) - continue; - - 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_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX - for call, jmp or one of adc, add, and, cmp, or, sbb, sub, - test, xor instructions. */ - if (!relocx) - continue; - } - - /* We convert only to R_X86_64_PC32: - 1. Branch. - 2. R_X86_64_GOTPCREL since we can't modify REX byte. - 3. require_reloc_pc32 is true. - 4. PIC. - */ - to_reloc_pc32 = (opcode == 0xff - || !relocx - || require_reloc_pc32 - || is_pic); - - /* Get the symbol referred to by the reloc. */ + r_symndx = htab->r_sym (irel->r_info); if (r_symndx < symtab_hdr->sh_info) - { - Elf_Internal_Sym *isym; - - isym = bfd_sym_from_r_symndx (&htab->sym_cache, - abfd, r_symndx); - - symtype = ELF_ST_TYPE (isym->st_info); - - /* STT_GNU_IFUNC must keep GOTPCREL relocations and skip - relocation against undefined symbols. */ - if (symtype == STT_GNU_IFUNC || isym->st_shndx == SHN_UNDEF) - continue; - - if (isym->st_shndx == SHN_ABS) - tsec = bfd_abs_section_ptr; - else if (isym->st_shndx == SHN_COMMON) - tsec = bfd_com_section_ptr; - else if (isym->st_shndx == SHN_X86_64_LCOMMON) - tsec = &_bfd_elf_large_com_section; - else - tsec = bfd_section_from_elf_index (abfd, isym->st_shndx); - - h = NULL; - toff = isym->st_value; - } + h = elf_x86_64_get_local_sym_hash (htab, sec->owner, + (const Elf_Internal_Rela *) irel, + FALSE); else { - indx = r_symndx - symtab_hdr->sh_info; - h = elf_sym_hashes (abfd)[indx]; - BFD_ASSERT (h != NULL); - + 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; - - /* STT_GNU_IFUNC must keep GOTPCREL relocations. We also - avoid optimizing GOTPCREL relocations againt _DYNAMIC - since ld.so may use its link-time address. */ - if (h->type == STT_GNU_IFUNC) - continue; - - /* Undefined weak symbol is only bound locally in executable - and its reference is resolved as 0 without relocation - overflow. We can only perform this optimization for - GOTPCRELX relocations since we need to modify REX byte. - It is OK convert mov with R_X86_64_GOTPCREL to - R_X86_64_PC32. */ - if ((relocx || opcode == 0x8b) - && UNDEFINED_WEAK_RESOLVED_TO_ZERO (link_info, - TRUE, - elf_x86_64_hash_entry (h))) - { - if (opcode == 0xff) - { - /* Skip for branch instructions since R_X86_64_PC32 - may overflow. */ - if (require_reloc_pc32) - continue; - } - else if (relocx) - { - /* For non-branch instructions, we can convert to - R_X86_64_32/R_X86_64_32S since we know if there - is a REX byte. */ - to_reloc_pc32 = FALSE; - } - - /* Since we don't know the current PC when PIC is true, - we can't convert to R_X86_64_PC32. */ - if (to_reloc_pc32 && is_pic) - continue; - - goto convert; - } - else if ((h->def_regular - || h->root.type == bfd_link_hash_defined - || h->root.type == bfd_link_hash_defweak) - && h != htab->elf.hdynamic - && SYMBOL_REFERENCES_LOCAL (link_info, h)) - { - /* bfd_link_hash_new or bfd_link_hash_undefined 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_new - || h->root.type == bfd_link_hash_undefined)) - { - /* Skip since R_X86_64_32/R_X86_64_32S may overflow. */ - if (require_reloc_pc32) - continue; - goto convert; - } - tsec = h->root.u.def.section; - toff = h->root.u.def.value; - symtype = h->type; - } - else - continue; - } - - /* We can only estimate relocation overflow for R_X86_64_PC32. */ - if (!to_reloc_pc32) - goto convert; - - if (tsec->sec_info_type == SEC_INFO_TYPE_MERGE) - { - /* At this stage in linking, no SEC_MERGE symbol has been - adjusted, so all references to such symbols need to be - passed through _bfd_merged_section_offset. (Later, in - relocate_section, all SEC_MERGE symbols *except* for - section symbols have been adjusted.) - - gas may reduce relocations against symbols in SEC_MERGE - sections to a relocation against the section symbol when - the original addend was zero. When the reloc is against - a section symbol we should include the addend in the - offset passed to _bfd_merged_section_offset, since the - location of interest is the original symbol. On the - other hand, an access to "sym+addend" where "sym" is not - a section symbol should not include the addend; Such an - access is presumed to be an offset from "sym"; The - location of interest is just "sym". */ - if (symtype == STT_SECTION) - toff += raddend; - - toff = _bfd_merged_section_offset (abfd, &tsec, - elf_section_data (tsec)->sec_info, - toff); - - if (symtype != STT_SECTION) - toff += raddend; } - else - toff += raddend; - /* Don't convert if R_X86_64_PC32 relocation overflows. */ - if (tsec->output_section == sec->output_section) - { - if ((toff - roff + 0x80000000) > 0xffffffff) - continue; - } - else - { - bfd_signed_vma distance; - - /* At this point, we don't know the load addresses of TSEC - section nor SEC section. We estimate the distrance between - SEC and TSEC. We store the estimated distances in the - compressed_size field of the output section, which is only - used to decompress the compressed input section. */ - if (sec->output_section->compressed_size == 0) - { - asection *asect; - bfd_size_type size = 0; - for (asect = link_info->output_bfd->sections; - asect != NULL; - asect = asect->next) - /* Skip debug sections since compressed_size is used to - compress debug sections. */ - if ((asect->flags & SEC_DEBUGGING) == 0) - { - asection *i; - for (i = asect->map_head.s; - i != NULL; - i = i->map_head.s) - { - size = align_power (size, i->alignment_power); - size += i->size; - } - asect->compressed_size = size; - } - } - - /* Don't convert GOTPCREL relocations if TSEC isn't placed - after SEC. */ - distance = (tsec->output_section->compressed_size - - sec->output_section->compressed_size); - if (distance < 0) - continue; + /* STT_GNU_IFUNC must keep GOTPCREL relocations. */ + if (h != NULL && h->type == STT_GNU_IFUNC) + continue; - /* Take PT_GNU_RELRO segment into account by adding - maxpagesize. */ - if ((toff + distance + maxpagesize - roff + 0x80000000) - > 0xffffffff) - continue; - } + converted = FALSE; + if (!elf_x86_64_convert_load_reloc (abfd, sec, contents, irel, h, + &converted, link_info)) + goto error_return; -convert: - if (opcode == 0xff) + if (converted) { - /* We have "call/jmp *foo@GOTPCREL(%rip)". */ - unsigned int nop; - unsigned int disp; - bfd_vma nop_offset; - - /* Convert R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX to - R_X86_64_PC32. */ - modrm = bfd_get_8 (abfd, contents + roff - 1); - if (modrm == 0x25) + changed = converted; + if (h) { - /* Convert to "jmp foo nop". */ - modrm = 0xe9; - nop = NOP_OPCODE; - nop_offset = irel->r_offset + 3; - disp = bfd_get_32 (abfd, contents + irel->r_offset); - irel->r_offset -= 1; - bfd_put_32 (abfd, disp, contents + irel->r_offset); + if (h->got.refcount > 0) + h->got.refcount -= 1; } else { - /* 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 = irel->r_offset + 3; - disp = bfd_get_32 (abfd, contents + irel->r_offset); - irel->r_offset -= 1; - bfd_put_32 (abfd, disp, contents + irel->r_offset); - } - else - nop_offset = irel->r_offset - 2; + if (local_got_refcounts != NULL + && local_got_refcounts[r_symndx] > 0) + local_got_refcounts[r_symndx] -= 1; } - bfd_put_8 (abfd, nop, contents + nop_offset); - bfd_put_8 (abfd, modrm, contents + irel->r_offset - 1); - r_type = R_X86_64_PC32; - } - else - { - unsigned int rex; - unsigned int rex_mask = REX_R; - - if (r_type == R_X86_64_REX_GOTPCRELX) - rex = bfd_get_8 (abfd, contents + roff - 3); - else - rex = 0; - - if (opcode == 0x8b) - { - if (to_reloc_pc32) - { - /* Convert "mov foo@GOTPCREL(%rip), %reg" to - "lea foo(%rip), %reg". */ - opcode = 0x8d; - r_type = R_X86_64_PC32; - } - else - { - /* Convert "mov foo@GOTPCREL(%rip), %reg" to - "mov $foo, %reg". */ - opcode = 0xc7; - modrm = bfd_get_8 (abfd, contents + roff - 1); - modrm = 0xc0 | (modrm & 0x38) >> 3; - if ((rex & REX_W) != 0 - && ABI_64_P (link_info->output_bfd)) - { - /* Keep the REX_W bit in REX byte for LP64. */ - r_type = R_X86_64_32S; - goto rewrite_modrm_rex; - } - else - { - /* If the REX_W bit in REX byte isn't needed, - use R_X86_64_32 and clear the W bit to avoid - sign-extend imm32 to imm64. */ - r_type = R_X86_64_32; - /* Clear the W bit in REX byte. */ - rex_mask |= REX_W; - goto rewrite_modrm_rex; - } - } - } - else - { - /* R_X86_64_PC32 isn't supported. */ - if (to_reloc_pc32) - continue; - - modrm = bfd_get_8 (abfd, contents + roff - 1); - if (opcode == 0x85) - { - /* Convert "test %reg, foo@GOTPCREL(%rip)" to - "test $foo, %reg". */ - modrm = 0xc0 | (modrm & 0x38) >> 3; - opcode = 0xf7; - } - else - { - /* Convert "binop foo@GOTPCREL(%rip), %reg" to - "binop $foo, %reg". */ - modrm = 0xc0 | (modrm & 0x38) >> 3 | (opcode & 0x3c); - opcode = 0x81; - } - - /* Use R_X86_64_32 with 32-bit operand to avoid relocation - overflow when sign-extending imm32 to imm64. */ - r_type = (rex & REX_W) != 0 ? R_X86_64_32S : R_X86_64_32; - -rewrite_modrm_rex: - bfd_put_8 (abfd, modrm, contents + roff - 1); - - if (rex) - { - /* Move the R bit to the B bit in REX byte. */ - rex = (rex & ~rex_mask) | (rex & REX_R) >> 2; - bfd_put_8 (abfd, rex, contents + roff - 3); - } - - /* No addend for R_X86_64_32/R_X86_64_32S relocations. */ - irel->r_addend = 0; - } - - bfd_put_8 (abfd, opcode, contents + roff - 2); - } - - irel->r_info = htab->r_info (r_symndx, r_type); - changed_contents = TRUE; - changed_relocs = TRUE; - - 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; } } 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 { @@ -3424,7 +3453,7 @@ rewrite_modrm_rex: if (elf_section_data (sec)->relocs != internal_relocs) { - if (!changed_relocs) + if (!changed) free (internal_relocs); else elf_section_data (sec)->relocs = internal_relocs; |