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Subject[PATCH 3.13.y-ckt 01/53] x86/asm/entry/64: Fold the 'test_in_nmi' macro into its only user
Date
3.13.11-ckt25 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Denys Vlasenko <dvlasenk@redhat.com>

commit 0784b36448a2a85b95b6eb21a69b9045c896c065 upstream.

No code changes.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1427899858-7165-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
arch/x86/kernel/entry_64.S | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 082d3ce..f4c0444 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1706,19 +1706,7 @@ ENTRY(error_exit)
CFI_ENDPROC
END(error_exit)

-/*
- * Test if a given stack is an NMI stack or not.
- */
- .macro test_in_nmi reg stack nmi_ret normal_ret
- cmpq %\reg, \stack
- ja \normal_ret
- subq $EXCEPTION_STKSZ, %\reg
- cmpq %\reg, \stack
- jb \normal_ret
- jmp \nmi_ret
- .endm
-
- /* runs on exception stack */
+/* Runs on exception stack */
ENTRY(nmi)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
@@ -1779,8 +1767,18 @@ ENTRY(nmi)
* We check the variable because the first NMI could be in a
* breakpoint routine using a breakpoint stack.
*/
- lea 6*8(%rsp), %rdx
- test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
+ lea 6*8(%rsp), %rdx
+ /* Compare the NMI stack (rdx) with the stack we came from (4*8(%rsp)) */
+ cmpq %rdx, 4*8(%rsp)
+ /* If the stack pointer is above the NMI stack, this is a normal NMI */
+ ja first_nmi
+ subq $EXCEPTION_STKSZ, %rdx
+ cmpq %rdx, 4*8(%rsp)
+ /* If it is below the NMI stack, it is a normal NMI */
+ jb first_nmi
+ /* Ah, it is within the NMI stack, treat it as nested */
+ jmp nested_nmi
+
CFI_REMEMBER_STATE

nested_nmi:
--
1.9.1


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