[PATCH AUTOSEL 5.9 013/147] s390/startup: avoid save_area_sync overflow

Sasha Levin
2020-10-26T23:49:40Z

From: Vasily Gorbik <gor@linux.ibm.com>

[ Upstream commit 2835c2ea95d50625108e47a459e1a47f6be836ce ]

Currently we overflow save_area_sync and write over
save_area_async. Although this is not a real problem make
startup_pgm_check_handler consistent with late pgm check handler and
store [%r0,%r7] directly into gpregs_save_area.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/boot/head.S | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index dae10961d0724..1a2c2b1ed9649 100644
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -360,22 +360,23 @@ ENTRY(startup_kdump)
# the save area and does disabled wait with a faulty address.
#
ENTRY(startup_pgm_check_handler)
- stmg %r0,%r15,__LC_SAVE_AREA_SYNC
- la %r1,4095
- stctg %c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r1)
- mvc __LC_GPREGS_SAVE_AREA-4095(128,%r1),__LC_SAVE_AREA_SYNC
- mvc __LC_PSW_SAVE_AREA-4095(16,%r1),__LC_PGM_OLD_PSW
+ stmg %r8,%r15,__LC_SAVE_AREA_SYNC
+ la %r8,4095
+ stctg %c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r8)
+ stmg %r0,%r7,__LC_GPREGS_SAVE_AREA-4095(%r8)
+ mvc __LC_GPREGS_SAVE_AREA-4095+64(64,%r8),__LC_SAVE_AREA_SYNC
+ mvc __LC_PSW_SAVE_AREA-4095(16,%r8),__LC_PGM_OLD_PSW
mvc __LC_RETURN_PSW(16),__LC_PGM_OLD_PSW
ni __LC_RETURN_PSW,0xfc # remove IO and EX bits
ni __LC_RETURN_PSW+1,0xfb # remove MCHK bit
oi __LC_RETURN_PSW+1,0x2 # set wait state bit
- larl %r2,.Lold_psw_disabled_wait
- stg %r2,__LC_PGM_NEW_PSW+8
- l %r15,.Ldump_info_stack-.Lold_psw_disabled_wait(%r2)
+ larl %r9,.Lold_psw_disabled_wait
+ stg %r9,__LC_PGM_NEW_PSW+8
+ l %r15,.Ldump_info_stack-.Lold_psw_disabled_wait(%r9)
brasl %r14,print_pgm_check_info
.Lold_psw_disabled_wait:
- la %r1,4095
- lmg %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)
+ la %r8,4095
+ lmg %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r8)
lpswe __LC_RETURN_PSW # disabled wait
.Ldump_info_stack:
.long 0x5000 + PAGE_SIZE - STACK_FRAME_OVERHEAD
--
2.25.1