From: Andy Lutomirski <l...@kernel.org>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 0e181bb58143cb4a2e8f01c281b0816cd0e4798e upstream.
Now that do_nmi saves CR2, we don't need to save it in asm.
Signed-off-by: Andy Lutomirski <l...@kernel.org>
Reviewed-by: Steven Rostedt <rost...@goodmis.org>
Acked-by: Borislav Petkov <b...@suse.de>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Jiri Slaby <jsl...@suse.cz>
---
arch/x86/kernel/entry_64.S | 18 ------------------
1 file changed, 18 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 7b22af265d12..fd27e5b86d7b 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1876,29 +1876,11 @@ end_repeat_nmi:
call save_paranoid
DEFAULT_FRAME 0
- /*
- * Save off the CR2 register. If we take a page fault in the NMI then
- * it could corrupt the CR2 value. If the NMI preempts a page fault
- * handler before it was able to read the CR2 register, and then the
- * NMI itself takes a page fault, the page fault that was preempted
- * will read the information from the NMI page fault and not the
- * origin fault. Save it off and restore it if it changes.
- * Use the r12 callee-saved register.
- */
- movq %cr2, %r12
-
/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
movq %rsp,%rdi
movq $-1,%rsi
call do_nmi
- /* Did the NMI take a page fault? Restore cr2 if it did */
- movq %cr2, %rcx
- cmpq %rcx, %r12
- je 1f
- movq %r12, %cr2
-1:
-
testl %ebx,%ebx /* swapgs needed? */
jnz nmi_restore
nmi_swapgs:
--
2.5.0
--
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