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From 3d8ca014b31b43c78d3240b2574670f2ab38519c Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Thu, 21 Sep 2017 20:39:56 -0700
Subject: [PATCH 010/102] kaiser: fix regs to do_nmi() ifndef CONFIG_KAISER

pjt has observed that nmi's second (nmi_from_kernel) call to do_nmi()
adjusted the %rdi regs arg, rightly when CONFIG_KAISER, but wrongly
when not CONFIG_KAISER.

Although the minimal change is to add an #ifdef CONFIG_KAISER around
the addq line, that looks cluttered, and I prefer how the first call
to do_nmi() handled it: prepare args in %rdi and %rsi before getting
into the CONFIG_KAISER block, since it does not touch them at all.

And while we're here, place the "#ifdef CONFIG_KAISER" that follows
each, to enclose the "Unconditionally restore CR3" comment: matching
how the "Unconditionally use kernel CR3" comment above is enclosed.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/entry/entry_64.S | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index d84e3a7..57f7993 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1321,12 +1321,13 @@ ENTRY(nmi)
 	movq	%rax, %cr3
 #endif
 	call	do_nmi
+
+#ifdef CONFIG_KAISER
 	/*
 	 * Unconditionally restore CR3.  I know we return to
 	 * kernel code that needs user CR3, but do we ever return
 	 * to "user mode" where we need the kernel CR3?
 	 */
-#ifdef CONFIG_KAISER
 	popq	%rax
 	mov	%rax, %cr3
 #endif
@@ -1550,6 +1551,8 @@ end_repeat_nmi:
 	SWAPGS
 	xorl	%ebx, %ebx
 1:
+	movq	%rsp, %rdi
+	movq	$-1, %rsi
 #ifdef CONFIG_KAISER
 	/* Unconditionally use kernel CR3 for do_nmi() */
 	/* %rax is saved above, so OK to clobber here */
@@ -1562,16 +1565,14 @@ end_repeat_nmi:
 #endif
 
 	/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
-	movq	%rsp, %rdi
-	addq	$8, %rdi /* point %rdi at ptregs, fixed up for CR3 */
-	movq	$-1, %rsi
 	call	do_nmi
+
+#ifdef CONFIG_KAISER
 	/*
 	 * Unconditionally restore CR3.  We might be returning to
 	 * kernel code that needs user CR3, like just just before
 	 * a sysret.
 	 */
-#ifdef CONFIG_KAISER
 	popq	%rax
 	mov	%rax, %cr3
 #endif
-- 
2.7.4