linux-kernel - [tip: x86/bugs] x86/bugs: Avoid warning when overriding return thunk

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Message-ID: <175075954857.406.17152971756037290596.tip-bot2@tip-bot2>
Date: Tue, 24 Jun 2025 10:05:48 -0000
From: "tip-bot2 for Pawan Gupta" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Borislav Petkov <bp@...en8.de>,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/bugs] x86/bugs: Avoid warning when overriding return thunk

The following commit has been merged into the x86/bugs branch of tip:

Commit-ID:     9f85fdb9fc5a1bd308a10a0a7d7e34f2712ba58b
Gitweb:        https://git.kernel.org/tip/9f85fdb9fc5a1bd308a10a0a7d7e34f2712ba58b
Author:        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
AuthorDate:    Wed, 11 Jun 2025 10:29:31 -07:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Mon, 23 Jun 2025 12:21:30 +02:00

x86/bugs: Avoid warning when overriding return thunk

The purpose of the warning is to prevent an unexpected change to the return
thunk mitigation. However, there are legitimate cases where the return
thunk is intentionally set more than once. For example, ITS and SRSO both
can set the return thunk after retbleed has set it. In both the cases
retbleed is still mitigated.

Replace the warning with an info about the active return thunk.

Suggested-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/20250611-eibrs-fix-v4-3-5ff86cac6c61@linux.intel.com
---
 arch/x86/kernel/cpu/bugs.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 94d0de3..20696ab 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -113,10 +113,9 @@ void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk;
 
 static void __init set_return_thunk(void *thunk)
 {
-	if (x86_return_thunk != __x86_return_thunk)
-		pr_warn("x86/bugs: return thunk changed\n");
-
 	x86_return_thunk = thunk;
+
+	pr_info("active return thunk: %ps\n", thunk);
 }
 
 /* Update SPEC_CTRL MSR and its cached copy unconditionally */