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authorMichael S. Tsirkin <mst@redhat.com>2016-01-28 19:02:29 +0200
committerIngo Molnar <mingo@kernel.org>2016-01-29 09:40:10 +0100
commitbd922477d9350a3006d73dabb241400e6c4181b0 (patch)
treef51887c2a082da7527e36251f602422cfd66b0ab /arch/x86/include/asm/barrier.h
parent26cd83670f2f5a3d5b5514a1f7d96567cdb9558b (diff)
downloadlinux-bd922477d9350a3006d73dabb241400e6c4181b0.tar.bz2
locking/x86: Add cc clobber for ADDL
ADDL clobbers flags (such as CF) but barrier.h didn't tell this to GCC. Historically, GCC doesn't need one on x86, and always considers flags clobbered. We are probably missing the cc clobber in a *lot* of places for this reason. But even if not necessary, it's probably a good thing to add for documentation, and in case GCC semantcs ever change. Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization <virtualization@lists.linux-foundation.org> Link: http://lkml.kernel.org/r/1453921746-16178-2-git-send-email-mst@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/barrier.h')
-rw-r--r--arch/x86/include/asm/barrier.h9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index a584e1c50918..a65bdb10246a 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -15,9 +15,12 @@
* Some non-Intel clones support out of order store. wmb() ceases to be a
* nop for these.
*/
-#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
-#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
-#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
+#define mb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "mfence", \
+ X86_FEATURE_XMM2) ::: "memory", "cc")
+#define rmb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "lfence", \
+ X86_FEATURE_XMM2) ::: "memory", "cc")
+#define wmb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "sfence", \
+ X86_FEATURE_XMM2) ::: "memory", "cc")
#else
#define mb() asm volatile("mfence":::"memory")
#define rmb() asm volatile("lfence":::"memory")