[PATCH v13 10/35] x86/objtool: Teach objtool about ERET[US]

[Xin Li <xin3.li@xxxxxxxxx>]

From: "H. Peter Anvin (Intel)" <hpa@xxxxxxxxx>

Update the objtool decoder to know about the ERET[US] instructions
(type INSN_CONTEXT_SWITCH).

Signed-off-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
---
 tools/objtool/arch/x86/decode.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index e327cd827135..3a1d80a7878d 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -509,11 +509,20 @@ int arch_decode_instruction(struct objtool_file *file, 
const struct section *sec
 
                if (op2 == 0x01) {
 
-                       if (modrm == 0xca)
-                               insn->type = INSN_CLAC;
-                       else if (modrm == 0xcb)
-                               insn->type = INSN_STAC;
-
+                       switch (insn_last_prefix_id(&ins)) {
+                       case INAT_PFX_REPE:
+                       case INAT_PFX_REPNE:
+                               if (modrm == 0xca)
+                                       /* eretu/erets */
+                                       insn->type = INSN_CONTEXT_SWITCH;
+                               break;
+                       default:
+                               if (modrm == 0xca)
+                                       insn->type = INSN_CLAC;
+                               else if (modrm == 0xcb)
+                                       insn->type = INSN_STAC;
+                               break;
+                       }
                } else if (op2 >= 0x80 && op2 <= 0x8f) {
 
                        insn->type = INSN_JUMP_CONDITIONAL;
-- 
2.43.0