[PATCH v2 2/3] objtool,x86: Additionally decode: mov %rsp, (%reg)

[Peter Zijlstra]

Where we already decode: mov %rsp, %reg, also decode mov %rsp, (%reg).

Nothing should match for this new stack-op.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 tools/objtool/arch/x86/decode.c |   23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -222,14 +222,24 @@ int arch_decode_instruction(const struct
 		break;
 
 	case 0x89:
-		if (rex_w && !rex_r && modrm_mod == 3 && modrm_reg == 4) {
+		if (rex_w && !rex_r && modrm_reg == 4) {
 
-			/* mov %rsp, reg */
+			/* mov %rsp, */
 			ADD_OP(op) {
 				op->src.type = OP_SRC_REG;
 				op->src.reg = CFI_SP;
-				op->dest.type = OP_DEST_REG;
-				op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
+				if (modrm_mod == 3) {
+
+					/* mov %rsp, reg */
+					op->dest.type = OP_DEST_REG;
+					op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
+
+				} else if (modrm_mod == 0) {
+
+					/* mov %rsp, (%reg) */
+					op->dest.type = OP_DEST_REG_INDIRECT;
+					op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
+				}
 			}
 			break;
 		}
@@ -259,8 +269,10 @@ int arch_decode_instruction(const struct
 				op->dest.reg = CFI_BP;
 				op->dest.offset = insn.displacement.value;
 			}
+			break;
+		}
 
-		} else if (rex_w && !rex_b && modrm_rm == 4 && sib == 0x24) {
+		if (rex_w && !rex_b && modrm_rm == 4 && sib == 0x24) {
 
 			/* mov reg, disp(%rsp) */
 			ADD_OP(op) {
@@ -270,6 +282,7 @@ int arch_decode_instruction(const struct
 				op->dest.reg = CFI_SP;
 				op->dest.offset = insn.displacement.value;
 			}
+			break;
 		}
 
 		break;