diff options
Diffstat (limited to 'tools/objtool/arch/x86/decode.c')
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 144 |
1 files changed, 134 insertions, 10 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 549813cff8ab..7e8b5bedd946 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -11,11 +11,15 @@ #include "../../../arch/x86/lib/inat.c" #include "../../../arch/x86/lib/insn.c" +#define CONFIG_64BIT 1 +#include <asm/nops.h> + #include <asm/orc_types.h> #include <objtool/check.h> #include <objtool/elf.h> #include <objtool/arch.h> #include <objtool/warn.h> +#include <arch/elf.h> static unsigned char op_to_cfi_reg[][2] = { {CFI_AX, CFI_R8}, @@ -90,7 +94,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, struct list_head *ops_list) { struct insn insn; - int x86_64, sign; + int x86_64, sign, ret; unsigned char op1, op2, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0, sib = 0; @@ -101,10 +105,9 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, if (x86_64 == -1) return -1; - insn_init(&insn, sec->data->d_buf + offset, maxlen, x86_64); - insn_get_length(&insn); - - if (!insn_complete(&insn)) { + ret = insn_decode(&insn, sec->data->d_buf + offset, maxlen, + x86_64 ? INSN_MODE_64 : INSN_MODE_32); + if (ret < 0) { WARN("can't decode instruction at %s:0x%lx", sec->name, offset); return -1; } @@ -596,11 +599,11 @@ void arch_initial_func_cfi_state(struct cfi_init_state *state) const char *arch_nop_insn(int len) { static const char nops[5][5] = { - /* 1 */ { 0x90 }, - /* 2 */ { 0x66, 0x90 }, - /* 3 */ { 0x0f, 0x1f, 0x00 }, - /* 4 */ { 0x0f, 0x1f, 0x40, 0x00 }, - /* 5 */ { 0x0f, 0x1f, 0x44, 0x00, 0x00 }, + { BYTES_NOP1 }, + { BYTES_NOP2 }, + { BYTES_NOP3 }, + { BYTES_NOP4 }, + { BYTES_NOP5 }, }; if (len < 1 || len > 5) { @@ -611,6 +614,122 @@ const char *arch_nop_insn(int len) return nops[len-1]; } +/* asm/alternative.h ? */ + +#define ALTINSTR_FLAG_INV (1 << 15) +#define ALT_NOT(feat) ((feat) | ALTINSTR_FLAG_INV) + +struct alt_instr { + s32 instr_offset; /* original instruction */ + s32 repl_offset; /* offset to replacement instruction */ + u16 cpuid; /* cpuid bit set for replacement */ + u8 instrlen; /* length of original instruction */ + u8 replacementlen; /* length of new instruction */ +} __packed; + +static int elf_add_alternative(struct elf *elf, + struct instruction *orig, struct symbol *sym, + int cpuid, u8 orig_len, u8 repl_len) +{ + const int size = sizeof(struct alt_instr); + struct alt_instr *alt; + struct section *sec; + Elf_Scn *s; + + sec = find_section_by_name(elf, ".altinstructions"); + if (!sec) { + sec = elf_create_section(elf, ".altinstructions", + SHF_WRITE, size, 0); + + if (!sec) { + WARN_ELF("elf_create_section"); + return -1; + } + } + + s = elf_getscn(elf->elf, sec->idx); + if (!s) { + WARN_ELF("elf_getscn"); + return -1; + } + + sec->data = elf_newdata(s); + if (!sec->data) { + WARN_ELF("elf_newdata"); + return -1; + } + + sec->data->d_size = size; + sec->data->d_align = 1; + + alt = sec->data->d_buf = malloc(size); + if (!sec->data->d_buf) { + perror("malloc"); + return -1; + } + memset(sec->data->d_buf, 0, size); + + if (elf_add_reloc_to_insn(elf, sec, sec->sh.sh_size, + R_X86_64_PC32, orig->sec, orig->offset)) { + WARN("elf_create_reloc: alt_instr::instr_offset"); + return -1; + } + + if (elf_add_reloc(elf, sec, sec->sh.sh_size + 4, + R_X86_64_PC32, sym, 0)) { + WARN("elf_create_reloc: alt_instr::repl_offset"); + return -1; + } + + alt->cpuid = cpuid; + alt->instrlen = orig_len; + alt->replacementlen = repl_len; + + sec->sh.sh_size += size; + sec->changed = true; + + return 0; +} + +#define X86_FEATURE_RETPOLINE ( 7*32+12) + +int arch_rewrite_retpolines(struct objtool_file *file) +{ + struct instruction *insn; + struct reloc *reloc; + struct symbol *sym; + char name[32] = ""; + + list_for_each_entry(insn, &file->retpoline_call_list, call_node) { + + if (!strcmp(insn->sec->name, ".text.__x86.indirect_thunk")) + continue; + + reloc = insn->reloc; + + sprintf(name, "__x86_indirect_alt_%s_%s", + insn->type == INSN_JUMP_DYNAMIC ? "jmp" : "call", + reloc->sym->name + 21); + + sym = find_symbol_by_name(file->elf, name); + if (!sym) { + sym = elf_create_undef_symbol(file->elf, name); + if (!sym) { + WARN("elf_create_undef_symbol"); + return -1; + } + } + + if (elf_add_alternative(file->elf, insn, sym, + ALT_NOT(X86_FEATURE_RETPOLINE), 5, 5)) { + WARN("elf_add_alternative"); + return -1; + } + } + + return 0; +} + int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg) { struct cfi_reg *cfa = &insn->cfi.cfa; @@ -646,3 +765,8 @@ int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg) return 0; } + +bool arch_is_retpoline(struct symbol *sym) +{ + return !strncmp(sym->name, "__x86_indirect_", 15); +} |