From: Ingo Molnar <mi...@kernel.org>

(cherry picked from commit d72f4e29e6d84b7ec02ae93088aa459ac70e733b)

firmware_restrict_branch_speculation_*() recently started using
preempt_enable()/disable(), but those are relatively high level
primitives and cause build failures on some 32-bit builds.

Since we want to keep <asm/nospec-branch.h> low level, convert
them to macros to avoid header hell...

Cc: David Woodhouse <d...@amazon.co.uk>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: arjan.van.de....@intel.com
Cc: b...@alien8.de
Cc: dave.han...@intel.com
Cc: jmatt...@google.com
Cc: karah...@amazon.de
Cc: k...@vger.kernel.org
Cc: pbonz...@redhat.com
Cc: rkrc...@redhat.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
[Youquan Song: port to 4.4]
Signed-off-by: Youquan Song <youquan.s...@linux.intel.com>
---
 arch/x86/include/asm/nospec-branch.h | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h 
b/arch/x86/include/asm/nospec-branch.h
index 27582aa..4675f65 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -214,20 +214,22 @@ static inline void 
indirect_branch_prediction_barrier(void)
 /*
  * With retpoline, we must use IBRS to restrict branch prediction
  * before calling into firmware.
+ *
+ * (Implemented as CPP macros due to header hell.)
  */
-static inline void firmware_restrict_branch_speculation_start(void)
-{
-       preempt_disable();
-       alternative_msr_write(MSR_IA32_SPEC_CTRL, SPEC_CTRL_IBRS,
-                             X86_FEATURE_USE_IBRS_FW);
-}
+#define firmware_restrict_branch_speculation_start()                   \
+do {                                                                   \
+       preempt_disable();                                              \
+       alternative_msr_write(MSR_IA32_SPEC_CTRL, SPEC_CTRL_IBRS,       \
+                             X86_FEATURE_USE_IBRS_FW);                 \
+} while (0)
 
-static inline void firmware_restrict_branch_speculation_end(void)
-{
-       alternative_msr_write(MSR_IA32_SPEC_CTRL, 0,
-                             X86_FEATURE_USE_IBRS_FW);
-       preempt_enable();
-}
+#define firmware_restrict_branch_speculation_end()                     \
+do {                                                                   \
+       alternative_msr_write(MSR_IA32_SPEC_CTRL, 0,                    \
+                             X86_FEATURE_USE_IBRS_FW);                 \
+       preempt_enable();                                               \
+} while (0)
 
 #endif /* __ASSEMBLY__ */
 
-- 
1.9.1

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