linux-kernel - [PATCH v2 3/7] x86/bugs: Exit early if return thunk is already set

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Message-ID: <20250521-eibrs-fix-v2-3-70e2598e932c@linux.intel.com>
Date: Wed, 21 May 2025 19:44:53 -0700
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To: x86@...nel.org
Cc: David Kaplan <david.kaplan@....com>, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>
Subject: [PATCH v2 3/7] x86/bugs: Exit early if return thunk is already set

ITS and retbleed can both set CDT return thunk. If the exact same return
thunk is already set, avoid the warning and exit early.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
---
 arch/x86/kernel/cpu/bugs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 20d7d14b08298d4f610f2ebc7f13a490ee3d957a..a088302b320cf68344e28be7710b5a3582bba9ea 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -113,6 +113,9 @@ void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk;
 
 static void __init set_return_thunk(void *thunk)
 {
+	if (thunk == x86_return_thunk)
+		return;
+
 	if (x86_return_thunk != __x86_return_thunk)
 		pr_warn("x86/bugs: return thunk changed\n");
 

-- 
2.34.1