[PATCH AUTOSEL 5.4 310/330] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline

From: Sasha Levin
Date: Thu Sep 17 2020 - 22:07:58 EST


From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200505134340.902709267@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 5c24a7b351665..b222a35959467 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -320,7 +320,7 @@ 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;

@@ -341,7 +341,7 @@ 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