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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2013-09-17 07:48:44 (GMT) |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-10-24 15:16:53 (GMT) |
| commit | 4ae803253e4649803dc6e972bb5e59fc107cf474 (patch) | |
| tree | 62aa7337c3b93b3e548557ac0202d072a598f460 /arch/s390/include/asm/bitops.h | |
| parent | 370b0b5f7744d62a9ba6c25fd6b0dcba84419443 (diff) | |
| download | linux-4ae803253e4649803dc6e972bb5e59fc107cf474.tar.xz | |
s390/bitops: optimize set_bit() for constant values
Since zEC12 we have the interlocked-access facility 2 which allows to
use the instructions ni/oi/xi to update a single byte in storage with
compare-and-swap semantics.
So change set_bit(), clear_bit() and change_bit() to generate such code
instead of a compare-and-swap loop (or using the load-and-* instruction
family), if possible.
This reduces the text segment by yet another 8KB (defconfig).
Alternatively the long displacement variants niy/oiy/xiy could have
been used, but the extended displacement field is usually not needed
and therefore would only increase the size of the text segment again.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/bitops.h')
| -rw-r--r-- | arch/s390/include/asm/bitops.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h index 6038349..16df62d 100644 --- a/arch/s390/include/asm/bitops.h +++ b/arch/s390/include/asm/bitops.h @@ -151,6 +151,18 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *ptr) unsigned long *addr = __bitops_word(nr, ptr); unsigned long mask; +#ifdef CONFIG_HAVE_MARCH_ZEC12_FEATURES + if (__builtin_constant_p(nr)) { + unsigned char *caddr = __bitops_byte(nr, ptr); + + asm volatile( + "oi %0,%b1\n" + : "+Q" (*caddr) + : "i" (1 << (nr & 7)) + : "cc"); + return; + } +#endif mask = 1UL << (nr & (BITS_PER_LONG - 1)); __BITOPS_LOOP(addr, mask, __BITOPS_OR); } @@ -160,6 +172,18 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *ptr) unsigned long *addr = __bitops_word(nr, ptr); unsigned long mask; +#ifdef CONFIG_HAVE_MARCH_ZEC12_FEATURES + if (__builtin_constant_p(nr)) { + unsigned char *caddr = __bitops_byte(nr, ptr); + + asm volatile( + "ni %0,%b1\n" + : "+Q" (*caddr) + : "i" (~(1 << (nr & 7))) + : "cc"); + return; + } +#endif mask = ~(1UL << (nr & (BITS_PER_LONG - 1))); __BITOPS_LOOP(addr, mask, __BITOPS_AND); } @@ -169,6 +193,18 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *ptr) unsigned long *addr = __bitops_word(nr, ptr); unsigned long mask; +#ifdef CONFIG_HAVE_MARCH_ZEC12_FEATURES + if (__builtin_constant_p(nr)) { + unsigned char *caddr = __bitops_byte(nr, ptr); + + asm volatile( + "xi %0,%b1\n" + : "+Q" (*caddr) + : "i" (1 << (nr & 7)) + : "cc"); + return; + } +#endif mask = 1UL << (nr & (BITS_PER_LONG - 1)); __BITOPS_LOOP(addr, mask, __BITOPS_XOR); } |