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From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To: x86@kernel.org
Cc: David Kaplan <david.kaplan@amd.com>,
	linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Borislav Petkov <bp@alien8.de>
Subject: [PATCH v4 3/7] x86/bugs: Avoid warning when overriding return thunk
Date: Wed, 11 Jun 2025 10:29:31 -0700	[thread overview]
Message-ID: <20250611-eibrs-fix-v4-3-5ff86cac6c61@linux.intel.com> (raw)
In-Reply-To: <20250611-eibrs-fix-v4-0-5ff86cac6c61@linux.intel.com>

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@alien8.de>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@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 94d0de3e61aec32b3b67c8d21f89a8c67b93dff3..20696abd1bef90aaf852fef1299b93d27c1f4da6 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 */

-- 
2.34.1



  parent reply	other threads:[~2025-06-11 17:29 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-11 17:28 [PATCH v4 0/7] Retbleed fixes Pawan Gupta
2025-06-11 17:29 ` [PATCH v4 1/7] x86/retbleed: Avoid AUTO after the select step Pawan Gupta
2025-06-24 10:05   ` [tip: x86/bugs] x86/bugs: Avoid AUTO after the select step in the retbleed mitigation tip-bot2 for Pawan Gupta
2025-06-11 17:29 ` [PATCH v4 2/7] x86/retbleed: Simplify the =stuff checks Pawan Gupta
2025-06-24 10:05   ` [tip: x86/bugs] x86/bugs: Simplify the retbleed=stuff checks tip-bot2 for Pawan Gupta
2025-06-11 17:29 ` Pawan Gupta [this message]
2025-06-24 10:05   ` [tip: x86/bugs] x86/bugs: Avoid warning when overriding return thunk tip-bot2 for Pawan Gupta
2025-06-11 17:29 ` [PATCH v4 4/7] x86/its: Use switch/case to apply mitigation Pawan Gupta
2025-06-24 10:05   ` [tip: x86/bugs] x86/bugs: Use switch/case in its_apply_mitigation() tip-bot2 for Pawan Gupta
2025-06-11 17:30 ` [PATCH v4 5/7] x86/retbleed: Introduce cdt_possible() Pawan Gupta
2025-06-24 10:05   ` [tip: x86/bugs] x86/bugs: " tip-bot2 for Pawan Gupta
2025-06-11 17:30 ` [PATCH v4 6/7] x86/its: Remove =stuff dependency on retbleed Pawan Gupta
2025-06-24 10:05   ` [tip: x86/bugs] x86/bugs: Remove its=stuff " tip-bot2 for Pawan Gupta
2025-06-11 17:30 ` [PATCH v4 7/7] x86/its: Allow stuffing in eIBRS+retpoline mode also Pawan Gupta
2025-06-24 10:05   ` [tip: x86/bugs] x86/bugs: Allow ITS " tip-bot2 for Pawan Gupta
2025-06-24 12:23   ` tip-bot2 for Pawan Gupta
2025-06-22 16:01 ` [PATCH v4 0/7] Retbleed fixes Borislav Petkov
2025-06-23 18:35   ` Pawan Gupta
2025-06-24 14:53     ` Borislav Petkov

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