linux-kernel - [RFC 20/31] objtool: Add UD1 detection

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Message-ID: <20e0e2662239a042a10196e8f240ce596b250ae8.1725334260.git.jpoimboe@kernel.org>
Date: Mon,  2 Sep 2024 21:00:03 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: live-patching@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	x86@...nel.org,
	Miroslav Benes <mbenes@...e.cz>,
	Petr Mladek <pmladek@...e.com>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Song Liu <song@...nel.org>
Subject: [RFC 20/31] objtool: Add UD1 detection

A UD1 isn't a BUG and shouldn't be treated like one.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/arch/x86/decode.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 6b34b058a821..72d55dcd3d7f 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -528,11 +528,19 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 			/* sysenter, sysret */
 			insn->type = INSN_CONTEXT_SWITCH;
 
-		} else if (op2 == 0x0b || op2 == 0xb9) {
+		} else if (op2 == 0x0b) {
 
 			/* ud2 */
 			insn->type = INSN_BUG;
 
+		} else if (op2 == 0xb9) {
+
+			/*
+			 * ud1 - only used for the static call trampoline to
+			 * stop speculation.  Basically used like an int3.
+			 */
+			insn->type = INSN_TRAP;
+
 		} else if (op2 == 0x0d || op2 == 0x1f) {
 
 			/* nopl/nopw */
-- 
2.45.2