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s390/cpumf: fix qsi inline assembly

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The qsi inline assembly takes an initialized "cc" variable as output
operand but specifies it as write-to operand only instead of
read/write operand. This allows the compiler to omit the
initialization, which in fact it also does (gcc 6.1).

Use the "+" constraint modifier to fix this. In addition also use the
Q constraint to specify the hws_qsi_info_block memory location, so the
compiler can generate slightly better code. Also get rid of the cc
clobber since none of the instructions within the inline assembly
modify the condition code.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2016-12-10 10:37:32 +01:00 committed by Martin Schwidefsky
parent 6d7b2ee9d5
commit 259acc5c25
1 changed files with 3 additions and 7 deletions
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10
arch/s390/include/asm/cpu_mf.h
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@ -213,18 +213,14 @@ static inline int stcctm5(u64 num, u64 *val)
/* Query sampling information */
static inline int qsi(struct hws_qsi_info_block *info)
{
int cc;
cc = 1;
int cc = 1;
asm volatile(
"0: .insn s,0xb2860000,0(%1)\n"
"0: .insn s,0xb2860000,%1\n"
"1: lhi %0,0\n"
"2:\n"
EX_TABLE(0b, 2b) EX_TABLE(1b, 2b)
: "=d" (cc), "+a" (info)
: "m" (*info)
: "cc", "memory");
: "+d" (cc), "+Q" (*info));
return cc ? -EINVAL : 0;
}