diff options
Diffstat (limited to 'bfd/elf32-i386.c')
| -rw-r--r-- | bfd/elf32-i386.c | 301 |
1 files changed, 263 insertions, 38 deletions
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c index 85885f71e17..2159c7e3113 100644 --- a/bfd/elf32-i386.c +++ b/bfd/elf32-i386.c @@ -29,6 +29,7 @@ #include "objalloc.h" #include "hashtab.h" #include "dwarf2.h" +#include "opcode/i386.h" /* 386 uses REL relocations instead of RELA. */ #define USE_REL 1 @@ -146,9 +147,12 @@ static reloc_howto_type elf_howto_table[]= HOWTO(R_386_IRELATIVE, 0, 2, 32, FALSE, 0, complain_overflow_bitfield, bfd_elf_generic_reloc, "R_386_IRELATIVE", TRUE, 0xffffffff, 0xffffffff, FALSE), + HOWTO(R_386_LOAD_GOT32, 0, 2, 32, FALSE, 0, complain_overflow_bitfield, + bfd_elf_generic_reloc, "R_386_LOAD_GOT32", + TRUE, 0xffffffff, 0xffffffff, FALSE), /* Another gap. */ -#define R_386_ext2 (R_386_IRELATIVE + 1 - R_386_tls_offset) +#define R_386_ext2 (R_386_LOAD_GOT32 + 1 - R_386_tls_offset) #define R_386_vt_offset (R_386_GNU_VTINHERIT - R_386_ext2) /* GNU extension to record C++ vtable hierarchy. */ @@ -332,6 +336,10 @@ elf_i386_reloc_type_lookup (bfd *abfd ATTRIBUTE_UNUSED, TRACE ("BFD_RELOC_386_IRELATIVE"); return &elf_howto_table[R_386_IRELATIVE - R_386_tls_offset]; + case BFD_RELOC_386_LOAD_GOT32: + TRACE ("BFD_RELOC_386_LOAD_GOT32"); + return &elf_howto_table[R_386_LOAD_GOT32 - R_386_tls_offset]; + case BFD_RELOC_VTABLE_INHERIT: TRACE ("BFD_RELOC_VTABLE_INHERIT"); return &elf_howto_table[R_386_GNU_VTINHERIT - R_386_vt_offset]; @@ -1468,7 +1476,7 @@ elf_i386_tls_transition (struct bfd_link_info *info, bfd *abfd, /* Rename some of the generic section flags to better document how they are used here. */ -#define need_convert_mov_to_lea sec_flg0 +#define need_convert_mov_and_branch sec_flg0 /* Look through the relocs for a section during the first phase, and calculate needed space in the global offset table, procedure linkage @@ -1580,6 +1588,7 @@ elf_i386_check_relocs (bfd *abfd, case R_386_PC32: case R_386_PLT32: case R_386_GOT32: + case R_386_LOAD_GOT32: if (htab->elf.dynobj == NULL) htab->elf.dynobj = abfd; if (!_bfd_elf_create_ifunc_sections (htab->elf.dynobj, info)) @@ -1637,6 +1646,7 @@ elf_i386_check_relocs (bfd *abfd, /* Fall through */ case R_386_GOT32: + case R_386_LOAD_GOT32: case R_386_TLS_GD: case R_386_TLS_GOTDESC: case R_386_TLS_DESC_CALL: @@ -1647,7 +1657,10 @@ elf_i386_check_relocs (bfd *abfd, switch (r_type) { default: - case R_386_GOT32: tls_type = GOT_NORMAL; break; + case R_386_GOT32: + case R_386_LOAD_GOT32: + tls_type = GOT_NORMAL; + break; case R_386_TLS_GD: tls_type = GOT_TLS_GD; break; case R_386_TLS_GOTDESC: case R_386_TLS_DESC_CALL: @@ -1940,9 +1953,9 @@ do_size: return FALSE; } - if (r_type == R_386_GOT32 + if ((r_type == R_386_GOT32 || r_type == R_386_LOAD_GOT32) && (h == NULL || h->type != STT_GNU_IFUNC)) - sec->need_convert_mov_to_lea = 1; + sec->need_convert_mov_and_branch = 1; } return TRUE; @@ -2066,6 +2079,7 @@ elf_i386_gc_sweep_hook (bfd *abfd, case R_386_TLS_IE: case R_386_TLS_GOTIE: case R_386_GOT32: + case R_386_LOAD_GOT32: if (h != NULL) { if (h->got.refcount > 0) @@ -2711,14 +2725,18 @@ elf_i386_readonly_dynrelocs (struct elf_link_hash_entry *h, void *inf) } /* Convert - mov foo@GOT(%reg), %reg + mov foo@GOT[(%reg)], %reg to - lea foo@GOTOFF(%reg), %reg - with the local symbol, foo. */ + lea foo[@GOTOFF(%reg)], %reg + with the local symbol, foo, and convert + call/jmp *foo@GOT[(%reg)] + to + nop call foo/jmp foo nop + with the locally defined function, foo. */ static bfd_boolean -elf_i386_convert_mov_to_lea (bfd *abfd, asection *sec, - struct bfd_link_info *link_info) +elf_i386_convert_mov_and_branch (bfd *abfd, asection *sec, + struct bfd_link_info *link_info) { Elf_Internal_Shdr *symtab_hdr; Elf_Internal_Rela *internal_relocs; @@ -2735,7 +2753,7 @@ elf_i386_convert_mov_to_lea (bfd *abfd, asection *sec, /* Nothing to do if there is no need or no output. */ if ((sec->flags & (SEC_CODE | SEC_RELOC)) != (SEC_CODE | SEC_RELOC) - || sec->need_convert_mov_to_lea == 0 + || sec->need_convert_mov_and_branch == 0 || bfd_is_abs_section (sec->output_section)) return TRUE; @@ -2769,34 +2787,57 @@ elf_i386_convert_mov_to_lea (bfd *abfd, asection *sec, unsigned int r_symndx = ELF32_R_SYM (irel->r_info); unsigned int indx; struct elf_link_hash_entry *h; + bfd_vma roff; + unsigned int opcode; + unsigned int modrm; + bfd_boolean baseless; + unsigned int new_r_type; + const char *name; + Elf_Internal_Sym *isym; + unsigned int disp; + unsigned int nop; + bfd_vma nop_offset; - if (r_type != R_386_GOT32) + if (r_type != R_386_GOT32 && r_type != R_386_LOAD_GOT32) continue; - /* Get the symbol referred to by the reloc. */ + roff = irel->r_offset; + + if (roff < 2) + continue; + + opcode = bfd_get_8 (abfd, contents + roff - 2); + + if (!(opcode == 0x8b + && (r_type == R_386_GOT32 || r_type == R_386_LOAD_GOT32)) + && !(opcode == 0xff && r_type == R_386_LOAD_GOT32)) + continue; + + /* Try to convert R_386_GOT32 and R_386_LOAD_GOT32. Get the + symbol referred to by the reloc. */ if (r_symndx < symtab_hdr->sh_info) { - Elf_Internal_Sym *isym; - isym = bfd_sym_from_r_symndx (&htab->sym_cache, abfd, r_symndx); - /* STT_GNU_IFUNC must keep R_386_GOT32 relocation. */ - if (ELF_ST_TYPE (isym->st_info) != STT_GNU_IFUNC - && irel->r_offset >= 2 - && bfd_get_8 (abfd, contents + irel->r_offset - 2) == 0x8b) + /* STT_GNU_IFUNC must keep GOT32 relocation. */ + if (ELF_ST_TYPE (isym->st_info) != STT_GNU_IFUNC) { - bfd_put_8 (abfd, 0x8d, contents + irel->r_offset - 2); - irel->r_info = ELF32_R_INFO (r_symndx, R_386_GOTOFF); if (local_got_refcounts != NULL && local_got_refcounts[r_symndx] > 0) local_got_refcounts[r_symndx] -= 1; - changed_contents = TRUE; - changed_relocs = TRUE; + h = NULL; + if (opcode == 0x8b) + /* Convert "mov *foo@GOT[(%reg)], %reg". */ + goto convert_mov_to_gotoff; + else + /* Convert "call/jmp *foo@GOT[(%reg)]". */ + goto convert_branch_to_gotoff; } continue; } + isym = NULL; indx = r_symndx - symtab_hdr->sh_info; h = elf_sym_hashes (abfd)[indx]; BFD_ASSERT (h != NULL); @@ -2805,21 +2846,176 @@ elf_i386_convert_mov_to_lea (bfd *abfd, asection *sec, || h->root.type == bfd_link_hash_warning) h = (struct elf_link_hash_entry *) h->root.u.i.link; - /* STT_GNU_IFUNC must keep R_386_GOT32 relocation. We also avoid - optimizing _DYNAMIC since ld.so may use its link-time address. */ - if (h->def_regular - && h->type != STT_GNU_IFUNC - && h != htab->elf.hdynamic - && SYMBOL_REFERENCES_LOCAL (link_info, h) - && irel->r_offset >= 2 - && bfd_get_8 (abfd, contents + irel->r_offset - 2) == 0x8b) + if (opcode == 0xff && r_type == R_386_LOAD_GOT32) + { + /* We have "call/jmp *foo@GOT[(%reg)]". */ + if (h->def_regular + && SYMBOL_REFERENCES_LOCAL (link_info, h)) + { + /* The function is defined. But STT_GNU_IFUNC must keep + R_386_LOAD_GOT32 relocation. */ + if (h->type != STT_GNU_IFUNC) + { +convert_branch_to_gotoff: + modrm = bfd_get_8 (abfd, contents + irel->r_offset - 1); + /* Convert R_386_LOAD_GOT32 to R_386_PC32. */ + if (modrm == 0x15 + || (modrm >= 0x90 && modrm <= 0x97)) + modrm = 0xe8; + else if (modrm == 0x25 + || (modrm >= 0xa0 && modrm <= 0xa7)) + modrm = 0xe9; + else + /* Skip "lcall/ljmp *foo@GOT[(%reg)]". */ + continue; + /* When converting to PC-relative relocation, we + need to adjust addend by 4. */ + disp = bfd_get_32 (abfd, contents + irel->r_offset); + disp -= 4; + if (modrm == 0xe9) + { + /* Convert to "jmp foo nop". */ + nop = NOP_OPCODE; + nop_offset = irel->r_offset + 3; + irel->r_offset -= 1; + } + else + { + /* Convert to "nop call foo". ADDR_PREFIX_OPCODE + is a nop prefix. */ + nop = ADDR_PREFIX_OPCODE; + nop_offset = irel->r_offset - 2; + } + bfd_put_8 (abfd, nop, contents + nop_offset); + bfd_put_8 (abfd, modrm, contents + irel->r_offset - 1); + bfd_put_32 (abfd, disp, 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; + } + changed_contents = TRUE; + changed_relocs = TRUE; + } + } + else + { + /* The function is undefined. */ + modrm = bfd_get_8 (abfd, contents + irel->r_offset - 1); + baseless = (modrm & 0xc7) == 0x5; + if (bfd_link_pic (link_info)) + { + /* For PIC, we leave "call/jmp *foo@GOT(%reg)" alone + and disallow "call/jmp *foo@GOT" since we don't + know what the GOT base is. */ + if (baseless) + { +baseless_error: + if (h) + name = h->root.root.string; + else + name = bfd_elf_sym_name (abfd, symtab_hdr, + isym, NULL); + (*_bfd_error_handler) + (_("%B: direct GOT relocation R_386_LOAD_GOT32 against `%s' without base register can not be used when making a shared object"), + abfd, name); + goto error_return; + } + } + else if (!baseless) + { + /* For non-PIC, convert "call/jmp *foo@GOT(%reg)" + to "call/jmp *foo@GOT" since we don't know if + REG is the GOT base. No need to convert + "call/jmp *foo@GOT". */ + if (modrm >= 0x90 && modrm <= 0x97) + /* Convert to "call *foo@GOT". */ + modrm = 0x15; + else if (modrm >= 0xa0 && modrm <= 0xa7) + /* Convert to "jmp *foo@GOT". */ + modrm = 0x25; + else + /* Skip "lcall/ljmp *foo@GOT(%reg)". */ + continue; + bfd_put_8 (abfd, modrm, contents + irel->r_offset - 1); + changed_contents = TRUE; + } + } + } + else { - bfd_put_8 (abfd, 0x8d, contents + irel->r_offset - 2); - irel->r_info = ELF32_R_INFO (r_symndx, R_386_GOTOFF); - if (h->got.refcount > 0) - h->got.refcount -= 1; - changed_contents = TRUE; - changed_relocs = TRUE; + /* STT_GNU_IFUNC must keep GOT32 relocation. */ + if (h->def_regular + && h->type != STT_GNU_IFUNC + && SYMBOL_REFERENCES_LOCAL (link_info, h)) + { + /* Avoid optimizing _DYNAMIC since ld.so may use its + link-time address. Convert R_386_LOAD_GOT32 in + "mov _DYNAMIC@GOT(%reg), %reg" to R_386_GOT32 to + avoid adding the GOT base in non-PIC mode in + elf_i386_relocate_section. */ + if (h == htab->elf.hdynamic) + { + if (r_type == R_386_LOAD_GOT32) + { + irel->r_info = ELF32_R_INFO (r_symndx, + R_386_GOT32); + changed_relocs = TRUE; + } + continue; + } + + if (h->got.refcount > 0) + h->got.refcount -= 1; + +convert_mov_to_gotoff: + bfd_put_8 (abfd, 0x8d, contents + irel->r_offset - 2); + modrm = bfd_get_8 (abfd, contents + irel->r_offset - 1); + baseless = (modrm & 0xc7) == 0x5; + /* For PIC, disallow "mov foo@GOT, %reg" since we don't + know what the GOT base is. */ + if (baseless && bfd_link_pic (link_info)) + goto baseless_error; + if (r_type == R_386_LOAD_GOT32 + && (baseless || !bfd_link_pic (link_info))) + new_r_type = R_386_32; + else + new_r_type = R_386_GOTOFF; + irel->r_info = ELF32_R_INFO (r_symndx, new_r_type); + changed_contents = TRUE; + changed_relocs = TRUE; + /* For non-PIC, convert "lea foo@GOTOFF(%reg1), %reg2" + to "lea foo, %reg2". */ + if (!baseless && new_r_type == R_386_32) + goto convert_to_baseless; + } + else if (r_type == R_386_LOAD_GOT32) + { + /* Function is undefined. */ + modrm = bfd_get_8 (abfd, contents + irel->r_offset - 1); + baseless = (modrm & 0xc5) == 0x5; + + if (bfd_link_pic (link_info)) + { + /* For PIC, we leave "mov *foo@GOT(%reg), %reg" alone + and disallow "mov foo@GOT, %reg" since we don't + know what the GOT base is. */ + if (baseless) + goto baseless_error; + } + else if (!baseless) + { + /* For non-PIC, convert "mov foo@GOT(%reg1), %reg2" + to "mov foo@GOT, %reg2" since the GOT base will be + added in elf_i386_relocate_section. No need to + convert "mov foo@GOT, %reg". */ +convert_to_baseless: + modrm = 0x5 | (modrm & 0x38); + bfd_put_8 (abfd, modrm, contents + irel->r_offset - 1); + changed_contents = TRUE; + } + } } } @@ -2905,7 +3101,7 @@ elf_i386_size_dynamic_sections (bfd *output_bfd, struct bfd_link_info *info) { struct elf_dyn_relocs *p; - if (!elf_i386_convert_mov_to_lea (ibfd, s, info)) + if (!elf_i386_convert_mov_and_branch (ibfd, s, info)) return FALSE; for (p = ((struct elf_dyn_relocs *) @@ -3655,6 +3851,7 @@ elf_i386_relocate_section (bfd *output_bfd, goto do_relocation; case R_386_GOT32: + case R_386_LOAD_GOT32: base_got = htab->elf.sgot; off = h->got.offset; @@ -3732,6 +3929,34 @@ elf_i386_relocate_section (bfd *output_bfd, eh = (struct elf_i386_link_hash_entry *) h; switch (r_type) { + case R_386_LOAD_GOT32: + /* Resolve "call/jmp *GOT[(%reg)]"/"mov GOT[(%reg)], %reg". */ + if (h == NULL + || (h->plt.offset == (bfd_vma) -1 + && h->got.offset == (bfd_vma) -1) + || htab->elf.sgotplt == NULL) + abort (); + + offplt = (htab->elf.sgotplt->output_section->vma + + htab->elf.sgotplt->output_offset); + + /* It is relative to .got.plt section. */ + if (h->got.offset != (bfd_vma) -1) + /* Use GOT entry. */ + relocation = (htab->elf.sgot->output_section->vma + + htab->elf.sgot->output_offset + + h->got.offset - offplt); + else + /* Use GOTPLT entry. */ + relocation = (h->plt.offset / plt_entry_size - 1 + 3) * 4; + + /* If not PIC, add the .got.plt section address. */ + if (!bfd_link_pic (info)) + relocation += offplt; + + unresolved_reloc = FALSE; + break; + case R_386_GOT32: /* Relocation is to the entry for this symbol in the global offset table. */ |