4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Hugh Dickins <hu...@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 <hu...@google.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/x86/entry/entry_64.S | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1323,12 +1323,13 @@ 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
@@ -1552,6 +1553,8 @@ 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 */
@@ -1564,16 +1567,14 @@ 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
