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Subject[PATCH 4.1 32/65] kaiser: fix regs to do_nmi() ifndef CONFIG_KAISER
Date
From: Hugh Dickins <hughd@google.com>

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>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 487f0b73d82611a2dc48d7d78409e2e9d994006a)
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>

Conflicts:
arch/x86/entry/entry_64.S (not in this tree)
arch/x86/kernel/entry_64.S (patched instead of that)
---
arch/x86/kernel/entry_64.S | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1bda5ebd1013..8e4056d4b1d6 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1547,12 +1547,12 @@ 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
@@ -1772,6 +1772,8 @@ 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 */
@@ -1785,16 +1787,13 @@ end_repeat_nmi:
DEFAULT_FRAME 0 /* XXX: Do we need this? */

/* 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
--
2.16.2
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