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x86/speculation: Move firmware_restrict_branch_speculation_*() from C to CPP

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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 <dwmw@amazon.co.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: arjan.van.de.ven@intel.com
Cc: bp@alien8.de
Cc: dave.hansen@intel.com
Cc: jmattson@google.com
Cc: karahmed@amazon.de
Cc: kvm@vger.kernel.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2018-02-21 09:20:37 +01:00
parent ca41b97ed9
commit d72f4e29e6
1 changed files with 14 additions and 12 deletions
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26
arch/x86/include/asm/nospec-branch.h
View file

@ -257,20 +257,22 @@ 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__ */
#endif /* _ASM_X86_NOSPEC_BRANCH_H_ */