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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>
Subject: [PATCH v3 3/7] x86/bugs: Exit early if return thunk is already set
Date: Thu, 22 May 2025 18:21:02 -0700	[thread overview]
Message-ID: <20250522-eibrs-fix-v3-3-12704e291e1e@linux.intel.com> (raw)
In-Reply-To: <20250522-eibrs-fix-v3-0-12704e291e1e@linux.intel.com>

When the exact same return thunk is already set, avoid the warning and exit
early. This is to prepare for ITS to also set CDT return thunk independent
of retbleed.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.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 94d0de3e61aec32b3b67c8d21f89a8c67b93dff3..354593065025fd7c5727e955d76523777b3da9ee 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



  parent reply	other threads:[~2025-05-23  1:21 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-23  1:20 [PATCH v3 0/7] eIBRS fixes Pawan Gupta
2025-05-23  1:20 ` [PATCH v3 1/7] x86/retbleed: Avoid AUTO after the select step Pawan Gupta
2025-05-24  9:29   ` Borislav Petkov
2025-05-23  1:20 ` [PATCH v3 2/7] x86/retbleed: Simplify the =stuff checks Pawan Gupta
2025-05-24 11:16   ` Borislav Petkov
2025-05-23  1:21 ` Pawan Gupta [this message]
2025-05-23 10:28   ` [PATCH v3 3/7] x86/bugs: Exit early if return thunk is already set Nikolay Borisov
2025-05-24 11:27   ` Borislav Petkov
2025-05-28 21:55     ` Pawan Gupta
2025-05-23  1:21 ` [PATCH v3 4/7] x86/its: Use switch/case to apply mitigation Pawan Gupta
2025-05-23  1:21 ` [PATCH v3 5/7] x86/retbleed: Introduce cdt_possible() Pawan Gupta
2025-05-23  1:21 ` [PATCH v3 6/7] x86/its: Remove =stuff dependency on retbleed Pawan Gupta
2025-05-23  1:22 ` [PATCH v3 7/7] x86/its: Allow stuffing in eIBRS+retpoline mode also Pawan Gupta

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