This is a note to let you know that I've just added the patch titled
x86/speculation: Move firmware_restrict_branch_speculation_*() from C to CPP
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: x86-speculation-move-firmware_restrict_branch_speculation_-from-c-to-cpp.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From d72f4e29e6d84b7ec02ae93088aa459ac70e733b Mon Sep 17 00:00:00 2001
From: Ingo Molnar mingo@kernel.org Date: Wed, 21 Feb 2018 09:20:37 +0100 Subject: x86/speculation: Move firmware_restrict_branch_speculation_*() from C to CPP
From: Ingo Molnar mingo@kernel.org
commit d72f4e29e6d84b7ec02ae93088aa459ac70e733b upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/include/asm/nospec-branch.h | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-)
--- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -257,20 +257,22 @@ static inline void indirect_branch_predi /* * 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__ */
Patches currently in stable-queue which might be from mingo@kernel.org are
queue-4.9/x86-boot-objtool-annotate-indirect-jump-in-secondary_startup_64.patch queue-4.9/x86-retpoline-support-retpoline-builds-with-clang.patch queue-4.9/revert-x86-retpoline-simplify-vmexit_fill_rsb.patch queue-4.9/nospec-include-asm-barrier.h-dependency.patch queue-4.9/x86-speculation-use-ibrs-if-available-before-calling-into-firmware.patch queue-4.9/x86-speculation-move-firmware_restrict_branch_speculation_-from-c-to-cpp.patch queue-4.9/x86-speculation-objtool-annotate-indirect-calls-jumps-for-objtool.patch queue-4.9/x86-paravirt-objtool-annotate-indirect-calls.patch queue-4.9/nospec-kill-array_index_nospec_mask_check.patch