4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
commit 891f6a726cacbb87e5b06076693ffab53bd378d7 upstream.
In the critical section cleanup we must not mess with r1. For march=z9
or older, larl + ex (instead of exrl) are used with r1 as a temporary
register. This can clobber r1 in several interrupt handlers. Fix this by
using r11 as a temp register. r11 is being saved by all callers of
cleanup_critical.
Fixes: 6dd85fbb87 ("s390: move expoline assembler macros to a header")
Cc: stable@xxxxxxxxxxxxxxx #v4.16
Reported-by: Oliver Kurz <okurz@xxxxxxxx>
Reported-by: Petr Tesařík <ptesarik@xxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Reviewed-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/entry.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -1170,7 +1170,7 @@ cleanup_critical:
jl 0f
clg %r9,BASED(.Lcleanup_table+104) # .Lload_fpu_regs_end
jl .Lcleanup_load_fpu_regs
-0: BR_EX %r14
+0: BR_EX %r14,%r11
.align 8
.Lcleanup_table:
@@ -1200,7 +1200,7 @@ cleanup_critical:
ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE
lctlg %c1,%c1,__LC_USER_ASCE # load primary asce
larl %r9,sie_exit # skip forward to sie_exit
- BR_EX %r14
+ BR_EX %r14,%r11
#endif
.Lcleanup_system_call:
