From: Alexander Gordeev <agordeev@linux.ibm.com>
Date: Mon, 29 Mar 2021 18:35:07 +0200
Subject: s390/cpcmd: fix inline assembly register clobbering
Git-commit: 7a2f91441b2c1d81b77c1cd816a4659f4abc9cbe
Patch-mainline: v5.12-rc7
References: git-fixes

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@linux.ibm.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gcc/Local-Register-Variables.html
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 arch/s390/kernel/cpcmd.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/s390/kernel/cpcmd.c
+++ b/arch/s390/kernel/cpcmd.c
@@ -36,10 +36,12 @@ 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(
 		"	diag	%2,%0,0x8\n"