From: "Steven Rostedt (Red Hat)" <rost...@goodmis.org>
Linus mentioned that doing two compares can be replaced by a single
compare. That is, instead of:
movq $repeat_nmi, %rdx
cmpq 8(%rsp), %rdx
ja not_in_region
movq $end_repeat_nmi, %rdx
cmpq 8(%rsp), %rdx
ja in_region
we can replace that with:
movq 8(%rsp), %rdx
subq $repeat_nmi, %rdx
cmpq $end_repeat_nmi-repeat_nmi, %rdx
jb in_region
Inspired-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
---
arch/x86/entry/entry_64.S | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 044d18ebc43c..3aad759aace2 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1330,13 +1330,10 @@ ENTRY(nmi)
* resume the outer NMI.
*/
- movq $repeat_nmi, %rdx
- cmpq 8(%rsp), %rdx
- ja 1f
- movq $end_repeat_nmi, %rdx
- cmpq 8(%rsp), %rdx
- ja nested_nmi_out
-1:
+ movq 8(%rsp), %rdx
+ subq $repeat_nmi, %rdx
+ cmpq $end_repeat_nmi-repeat_nmi, %rdx
+ jb nested_nmi_out
/*
* Now check "NMI executing". If it's set, then we're nested.
--
2.10.2
