x86/asm/entry/64: Fold the 'test_in_nmi' macro into its only user

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>

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 03c52e2176809a562692ce1b89457bc8cc595680..386375d43d147debdbd90a0d8e3c2b9325754fd6 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1355,19 +1355,7 @@ 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
@@ -1428,8 +1416,18 @@ 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: