linux-kernel - [RFC][PATCH 04/17] objtool/x86: Fix SRSO mess

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Message-ID: <20230809072200.715361518@infradead.org>
Date:   Wed, 09 Aug 2023 09:12:22 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        David.Kaplan@....com, Andrew.Cooper3@...rix.com,
        jpoimboe@...nel.org, gregkh@...uxfoundation.org
Subject: [RFC][PATCH 04/17] objtool/x86: Fix SRSO mess

arch_is_rethunk() indicates those functions that will be considered
equivalent to INSN_RETURN and any callsite will be added to the
.return_sites section.

Notably: srso_untrain_ret, srso_safe_ret and __ret do not qualify.

The only thing that needs consideration is srso_safe_ret(), since that
is, like __x86_return_thunk, inside another instruction. Skip
validating that.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 tools/objtool/arch/x86/decode.c |    5 +----
 tools/objtool/check.c           |    2 +-
 2 files changed, 2 insertions(+), 5 deletions(-)

--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -824,8 +824,5 @@ bool arch_is_retpoline(struct symbol *sy
 
 bool arch_is_rethunk(struct symbol *sym)
 {
-	return !strcmp(sym->name, "__x86_return_thunk") ||
-	       !strcmp(sym->name, "srso_untrain_ret") ||
-	       !strcmp(sym->name, "srso_safe_ret") ||
-	       !strcmp(sym->name, "__ret");
+	return !strcmp(sym->name, "__x86_return_thunk");
 }
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -455,7 +455,7 @@ static int decode_instructions(struct ob
 				return -1;
 			}
 
-			if (func->return_thunk || func->alias != func)
+			if (func->return_thunk || !strcmp(func->name, "srso_safe_ret") || func->alias != func)
 				continue;
 
 			if (!find_insn(file, sec, func->offset)) {