+/* 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_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 (baseless && is_pic)
+ {
+ /* For PIC, disallow R_386_GOT32X without a base register
+ since we don't know what the GOT base is. */
+ 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 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_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)
+ {
+ struct elf_i386_link_hash_entry *eh
+ = (struct elf_i386_link_hash_entry *) h;
+
+ /* Convert to "nop call foo". ADDR_PREFIX_OPCODE
+ is a nop prefix. */
+ modrm = 0xe8;
+ /* To support TLS optimization, always use addr32 prefix
+ for "call *___tls_get_addr@GOT(%reg)". */
+ if (eh && eh->tls_get_addr == 1)
+ {
+ nop = 0x67;
+ nop_offset = irel->r_offset - 2;
+ }
+ else
+ {
+ 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;
+}
+
projects / external / binutils.git / blobdiff