Commit 4a4eefcd authored Aug 03, 2017 by Heiko Carstens Committed by Christian Borntraeger Aug 21, 2017

KVM: s390: sthyi: fix sthyi inline assembly



The sthyi inline assembly misses register r3 within the clobber
list. The sthyi instruction will always write a return code to
register "R2+1", which in this case would be r3. Due to that we may
have register corruption and see host crashes or data corruption
depending on how gcc decided to allocate and use registers during
compile time.

Fixes: 95ca2cb5 ("KVM: s390: Add sthyi emulation")
Cc: <stable@vger.kernel.org> # 4.8+
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

parent 4f899147

arch/s390/kvm/sthyi.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -394,7 +394,7 @@ static int sthyi(u64 vaddr)
		"srl %[cc],28\n"
		: [cc] "=d" (cc)
		: [code] "d" (code), [addr] "a" (addr)
		: "memory", "cc");
		: "3", "memory", "cc");
		return cc;
		}

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