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authorBorislav Petkov <bp@suse.de>2016-04-08 03:31:49 +0300
committerIngo Molnar <mingo@kernel.org>2016-04-13 11:20:42 +0300
commit96e5d28ae7a5250f3deb2434f1895c9daf48b1bd (patch)
tree5bd439d3de521744c90937879ba0ee3f032e1142 /arch/x86/entry
parent0230bb038fa99af0c425fc4cffed307e545a9642 (diff)
downloadlinux-96e5d28ae7a5250f3deb2434f1895c9daf48b1bd.tar.xz
x86/cpu: Add Erratum 88 detection on AMD
Erratum 88 affects old AMD K8s, where a SWAPGS fails to cause an input dependency on GS. Therefore, we need to MFENCE before it. But that MFENCE is expensive and unnecessary on the remaining x86 CPUs out there so patch it out on the CPUs which don't require it. Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Andy Lutomirski <luto@kernel.org Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rudolf Marek <r.marek@assembler.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/aec6b2df1bfc56101d4e9e2e5d5d570bf41663c6.1460075211.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry')
-rw-r--r--arch/x86/entry/entry_64.S2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 858b555e274b..64d2033d1e49 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -783,7 +783,7 @@ ENTRY(native_load_gs_index)
SWAPGS
gs_change:
movl %edi, %gs
-2: mfence /* workaround */
+2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
SWAPGS
popfq
ret