diff options
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 67 |
1 files changed, 48 insertions, 19 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 5ce7dc4d8a0a..78ae5be2fb70 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -72,6 +72,25 @@ unsigned long arch_jump_destination(struct instruction *insn) return -1; \ else for (list_add_tail(&op->list, ops_list); op; op = NULL) +/* + * Helpers to decode ModRM/SIB: + * + * r/m| AX CX DX BX | SP | BP | SI DI | + * | R8 R9 R10 R11 | R12 | R13 | R14 R15 | + * Mod+----------------+-----+-----+---------+ + * 00 | [r/m] |[SIB]|[IP+]| [r/m] | + * 01 | [r/m + d8] |[S+d]| [r/m + d8] | + * 10 | [r/m + d32] |[S+D]| [r/m + d32] | + * 11 | r/ m | + * + */ +#define is_RIP() ((modrm_rm & 7) == CFI_BP && modrm_mod == 0) +#define have_SIB() ((modrm_rm & 7) == CFI_SP && modrm_mod != 3) + +#define rm_is(reg) (have_SIB() ? \ + sib_base == (reg) && sib_index == CFI_SP : \ + modrm_rm == (reg)) + int arch_decode_instruction(const struct elf *elf, const struct section *sec, unsigned long offset, unsigned int maxlen, unsigned int *len, enum insn_type *type, @@ -83,7 +102,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, 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 /* , sib_scale = 0, sib_index = 0, sib_base = 0 */; + sib = 0, /* sib_scale = 0, */ sib_index = 0, sib_base = 0; struct stack_op *op = NULL; struct symbol *sym; @@ -125,11 +144,9 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, if (insn.sib.nbytes) { sib = insn.sib.bytes[0]; - /* - sib_scale = X86_SIB_SCALE(sib); + /* sib_scale = X86_SIB_SCALE(sib); */ sib_index = X86_SIB_INDEX(sib) + 8*rex_x; sib_base = X86_SIB_BASE(sib) + 8*rex_b; - */ } switch (op1) { @@ -218,7 +235,10 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, break; case 0x89: - if (rex_w && modrm_reg == CFI_SP) { + if (!rex_w) + break; + + if (modrm_reg == CFI_SP) { if (modrm_mod == 3) { /* mov %rsp, reg */ @@ -231,14 +251,17 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, break; } else { - /* skip nontrivial SIB */ - if ((modrm_rm & 7) == 4 && !(sib == 0x24 && rex_b == rex_x)) - break; - /* skip RIP relative displacement */ - if ((modrm_rm & 7) == 5 && modrm_mod == 0) + if (is_RIP()) break; + /* skip nontrivial SIB */ + if (have_SIB()) { + modrm_rm = sib_base; + if (sib_index != CFI_SP) + break; + } + /* mov %rsp, disp(%reg) */ ADD_OP(op) { op->src.type = OP_SRC_REG; @@ -253,7 +276,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, break; } - if (rex_w && modrm_mod == 3 && modrm_rm == CFI_SP) { + if (modrm_mod == 3 && modrm_rm == CFI_SP) { /* mov reg, %rsp */ ADD_OP(op) { @@ -267,6 +290,9 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, /* fallthrough */ case 0x88: + if (!rex_w) + break; + if ((modrm_mod == 1 || modrm_mod == 2) && modrm_rm == CFI_BP) { /* mov reg, disp(%rbp) */ @@ -280,7 +306,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, break; } - if (rex_w && modrm_rm == CFI_SP && sib == 0x24) { + if (modrm_mod != 3 && rm_is(CFI_SP)) { /* mov reg, disp(%rsp) */ ADD_OP(op) { @@ -299,7 +325,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, if (!rex_w) break; - if (modrm_mod == 1 && modrm_rm == CFI_BP) { + if ((modrm_mod == 1 || modrm_mod == 2) && modrm_rm == CFI_BP) { /* mov disp(%rbp), reg */ ADD_OP(op) { @@ -312,7 +338,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, break; } - if (modrm_mod != 3 && modrm_rm == CFI_SP && sib == 0x24) { + if (modrm_mod != 3 && rm_is(CFI_SP)) { /* mov disp(%rsp), reg */ ADD_OP(op) { @@ -337,14 +363,17 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, if (!rex_w) break; - /* skip nontrivial SIB */ - if ((modrm_rm & 7) == 4 && !(sib == 0x24 && rex_b == rex_x)) - break; - /* skip RIP relative displacement */ - if ((modrm_rm & 7) == 5 && modrm_mod == 0) + if (is_RIP()) break; + /* skip nontrivial SIB */ + if (have_SIB()) { + modrm_rm = sib_base; + if (sib_index != CFI_SP) + break; + } + /* lea disp(%src), %dst */ ADD_OP(op) { op->src.offset = insn.displacement.value; |