From: Heiko Carstens hca@linux.ibm.com
[ Upstream commit 4fa3b91bdee1b08348c82660668ca0ca34e271ad ]
Using register asm statements has been proven to be very error prone, especially when using code instrumentation where gcc may add function calls, which clobbers register contents in an unexpected way.
Therefore get rid of register asm statements in kvm code, even though there is currently nothing wrong with them. This way we know for sure that this bug class won't be introduced here.
Signed-off-by: Heiko Carstens hca@linux.ibm.com Reviewed-by: Christian Borntraeger borntraeger@de.ibm.com Reviewed-by: Thomas Huth thuth@redhat.com Reviewed-by: Cornelia Huck cohuck@redhat.com Reviewed-by: Claudio Imbrenda imbrenda@linux.ibm.com Link: https://lore.kernel.org/r/20210621140356.1210771-1-hca@linux.ibm.com [borntraeger@de.ibm.com: checkpatch strict fix] Signed-off-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/kvm/kvm-s390.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 20afffd6b982..f94b4f78d4da 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -327,31 +327,31 @@ static void allow_cpu_feat(unsigned long nr)
static inline int plo_test_bit(unsigned char nr) { - register unsigned long r0 asm("0") = (unsigned long) nr | 0x100; + unsigned long function = (unsigned long)nr | 0x100; int cc;
asm volatile( + " lgr 0,%[function]\n" /* Parameter registers are ignored for "test bit" */ " plo 0,0,0,0(0)\n" " ipm %0\n" " srl %0,28\n" : "=d" (cc) - : "d" (r0) - : "cc"); + : [function] "d" (function) + : "cc", "0"); return cc == 0; }
static __always_inline void __insn32_query(unsigned int opcode, u8 *query) { - register unsigned long r0 asm("0") = 0; /* query function */ - register unsigned long r1 asm("1") = (unsigned long) query; - asm volatile( - /* Parameter regs are ignored */ + " lghi 0,0\n" + " lgr 1,%[query]\n" + /* Parameter registers are ignored */ " .insn rrf,%[opc] << 16,2,4,6,0\n" : - : "d" (r0), "a" (r1), [opc] "i" (opcode) - : "cc", "memory"); + : [query] "d" ((unsigned long)query), [opc] "i" (opcode) + : "cc", "memory", "0", "1"); }
#define INSN_SORTL 0xb938