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-rw-r--r--arch/x86/kernel/entry_64.S20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 7d65133b51b..111f6bbd8b3 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1758,10 +1758,30 @@ 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: