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"