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x86/nmi/64: Remove asm code that saves CR2
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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>
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amluto authored and Ingo Molnar committed Jul 17, 2015
1 parent 9d05041 commit 0e181bb
Showing 1 changed file with 0 additions and 17 deletions.
17 changes: 0 additions & 17 deletions arch/x86/entry/entry_64.S
Original file line number Diff line number Diff line change
Expand Up @@ -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:
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