This is a note to let you know that I've just added the patch titled
s390/cpcmd: fix inline assembly register clobbering
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-cpcmd-fix-inline-assembly-register-clobbering.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 41728420e02b9b843269721fdbe35abd71e5548d
Author: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Date: Mon Mar 29 18:35:07 2021 +0200
s390/cpcmd: fix inline assembly register clobbering
[ Upstream commit 7a2f91441b2c1d81b77c1cd816a4659f4abc9cbe ]
Register variables initialized using arithmetic. That leads to
kasan instrumentaton code corrupting the registers contents.
Follow GCC guidlines and use temporary variables for assigning
init values to register variables.
Fixes: 94c12cc7d196 ("[S390] Inline assembly cleanup.")
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Link: https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gcc/Local-Register-Variables.html
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/s390/kernel/cpcmd.c b/arch/s390/kernel/cpcmd.c
index 7f768914fb4f..c15546c6fb66 100644
--- a/arch/s390/kernel/cpcmd.c
+++ b/arch/s390/kernel/cpcmd.c
@@ -37,10 +37,12 @@ static int diag8_noresponse(int cmdlen)
static int diag8_response(int cmdlen, char *response, int *rlen)
{
+ unsigned long _cmdlen = cmdlen | 0x40000000L;
+ unsigned long _rlen = *rlen;
register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
register unsigned long reg3 asm ("3") = (addr_t) response;
- register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
- register unsigned long reg5 asm ("5") = *rlen;
+ register unsigned long reg4 asm ("4") = _cmdlen;
+ register unsigned long reg5 asm ("5") = _rlen;
asm volatile(
" sam31\n"
