linux-kernel - [PATCH AUTOSEL 4.14 120/127] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always

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Date:   Thu, 17 Sep 2020 22:12:13 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.14 120/127] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline

From: Thomas Gleixner <tglx@...utronix.de>

[ Upstream commit a7ef9ba986b5fae9d80f8a7b31db0423687efe4e ]

Prevent the compiler from uninlining and creating traceable/probable
functions as this is invoked _after_ context tracking switched to
CONTEXT_USER and rcu idle.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20200505134340.902709267@linutronix.de
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/include/asm/nospec-branch.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 041d2a04be1d8..270448b178a7a 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -330,7 +330,7 @@ DECLARE_STATIC_KEY_FALSE(mds_idle_clear);
  * combination with microcode which triggers a CPU buffer flush when the
  * instruction is executed.
  */
-static inline void mds_clear_cpu_buffers(void)
+static __always_inline void mds_clear_cpu_buffers(void)
 {
 	static const u16 ds = __KERNEL_DS;
 
@@ -351,7 +351,7 @@ static inline void mds_clear_cpu_buffers(void)
  *
  * Clear CPU buffers if the corresponding static key is enabled
  */
-static inline void mds_user_clear_cpu_buffers(void)
+static __always_inline void mds_user_clear_cpu_buffers(void)
 {
 	if (static_branch_likely(&mds_user_clear))
 		mds_clear_cpu_buffers();
-- 
2.25.1