Patch "x86/speculation: Move firmware_restrict_branch_speculation_*() from C to CPP" has been added to the 4.15-stable tree

[<gregkh@linuxfoundation.org>]

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 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

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-4.15 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-4.15/x86-boot-objtool-annotate-indirect-jump-in-secondary_startup_64.patch
queue-4.15/x86-retpoline-support-retpoline-builds-with-clang.patch
queue-4.15/x86-ldt-avoid-warning-in-32-bit-builds-with-older-gcc.patch
queue-4.15/x86-entry-reduce-the-code-footprint-of-the-idtentry-macro.patch
queue-4.15/bug-use-pb-in-bug-and-stack-protector-failure.patch
queue-4.15/revert-x86-retpoline-simplify-vmexit_fill_rsb.patch
queue-4.15/nospec-include-asm-barrier.h-dependency.patch
queue-4.15/x86-mm-remove-stale-comment-about-kmemcheck.patch
queue-4.15/x86-mm-sme-objtool-annotate-indirect-call-in-sme_encrypt_execute.patch
queue-4.15/x86-speculation-use-ibrs-if-available-before-calling-into-firmware.patch
queue-4.15/x86-asm-improve-how-gen_-_suffixed_rmwcc-specify-clobbers.patch
queue-4.15/x86-64-realmode-add-instruction-suffix.patch
queue-4.15/x86-speculation-move-firmware_restrict_branch_speculation_-from-c-to-cpp.patch
queue-4.15/x86-speculation-objtool-annotate-indirect-calls-jumps-for-objtool.patch
queue-4.15/x86-paravirt-objtool-annotate-indirect-calls.patch
queue-4.15/x86-entry-64-use-xorl-for-faster-register-clearing.patch
queue-4.15/nospec-kill-array_index_nospec_mask_check.patch
queue-4.15/lib-bug.c-exclude-non-bug-warn-exceptions-from-report_bug.patch
queue-4.15/x86-io-apic-avoid-warning-in-32-bit-builds.patch