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s390/cpcmd: fix inline assembly register clobbering

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[ Upstream commit 7a2f91441b ]

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: 94c12cc7d1 ("[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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Alexander Gordeev
2021-03-29 18:35:07 +02:00
committed by Greg Kroah-Hartman
parent 7943f749f0
commit d9dc1b406c
1 changed files with 4 additions and 2 deletions
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arch/s390/kernel/cpcmd.c
+4 -2
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@@ -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(
" diag %2,%0,0x8\n"