The following commit has been merged into the objtool/core branch of tip:
Commit-ID: 2ee0c363492f1acc1082125218e6a80c0d7d502b
Gitweb: https://git.kernel.org/tip/2ee0c363492f1acc1082125218e6a80c0d7d502b
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 09 Feb 2021 21:29:16 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sat, 06 Mar 2021 12:44:23 +01:00
objtool,x86: Rewrite LEA decode
Current LEA decoding is a bunch of special cases, properly decode the
instruction, with exception of full SIB and RIP-relative modes.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20210211173627.143250641@xxxxxxxxxxxxx
---
tools/objtool/arch/x86/decode.c | 86 ++++++++++----------------------
1 file changed, 28 insertions(+), 58 deletions(-)
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 549813c..d8f0138 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -91,9 +91,10 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
{
struct insn insn;
int x86_64, sign;
- 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;
+ 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;
struct stack_op *op = NULL;
struct symbol *sym;
@@ -328,68 +329,37 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
break;
case 0x8d:
- if (sib == 0x24 && rex_w && !rex_b && !rex_x) {
-
- ADD_OP(op) {
- if (!insn.displacement.value) {
- /* lea (%rsp), reg */
- op->src.type = OP_SRC_REG;
- } else {
- /* lea disp(%rsp), reg */
- op->src.type = OP_SRC_ADD;
- op->src.offset = insn.displacement.value;
- }
- op->src.reg = CFI_SP;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
- }
-
- } else if (rex == 0x48 && modrm == 0x65) {
-
- /* lea disp(%rbp), %rsp */
- ADD_OP(op) {
- op->src.type = OP_SRC_ADD;
- op->src.reg = CFI_BP;
- op->src.offset = insn.displacement.value;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
- }
+ if (modrm_mod == 3) {
+ WARN("invalid LEA encoding at %s:0x%lx", sec->name, offset);
+ break;
+ }
- } else if (rex == 0x49 && modrm == 0x62 &&
- insn.displacement.value == -8) {
+ /* skip non 64bit ops */
+ if (!rex_w)
+ break;
- /*
- * lea -0x8(%r10), %rsp
- *
- * Restoring rsp back to its original value after a
- * stack realignment.
- */
- ADD_OP(op) {
- op->src.type = OP_SRC_ADD;
- op->src.reg = CFI_R10;
- op->src.offset = -8;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
- }
+ /* skip nontrivial SIB */
+ if (modrm_rm == 4 && !(sib == 0x24 && rex_b == rex_x))
+ break;
- } else if (rex == 0x49 && modrm == 0x65 &&
- insn.displacement.value == -16) {
+ /* skip RIP relative displacement */
+ if (modrm_rm == 5 && modrm_mod == 0)
+ break;
- /*
- * lea -0x10(%r13), %rsp
- *
- * Restoring rsp back to its original value after a
- * stack realignment.
- */
- ADD_OP(op) {
+ /* lea disp(%src), %dst */
+ ADD_OP(op) {
+ op->src.offset = insn.displacement.value;
+ if (!op->src.offset) {
+ /* lea (%src), %dst */
+ op->src.type = OP_SRC_REG;
+ } else {
+ /* lea disp(%src), %dst */
op->src.type = OP_SRC_ADD;
- op->src.reg = CFI_R13;
- op->src.offset = -16;
- op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_SP;
}
+ op->src.reg = op_to_cfi_reg[modrm_rm][rex_b];
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
}
-
break;
case 0x8f:
|