x86/nmi/64: Remove asm code that saves CR2

Now that do_nmi saves CR2, we don't need to save it in asm.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 3bb2c4302df1f8ba18e21b997fd5b51e8ec55c54..062feb4eb47840166b742bdeeac9da603b361a6a 100644 (file)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1415,28 +1415,11 @@ end_repeat_nmi:
         */
        call    paranoid_entry
 
-       /*
-        * 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: