diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2013-09-17 09:48:44 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-10-24 17:16:53 +0200 |
| commit | 4ae803253e4649803dc6e972bb5e59fc107cf474 (patch) | |
| tree | 62aa7337c3b93b3e548557ac0202d072a598f460 /arch/s390/kernel/head.S | |
| parent | 370b0b5f7744d62a9ba6c25fd6b0dcba84419443 (diff) | |
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/kernel/head.S')
| -rw-r--r-- | arch/s390/kernel/head.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S index fd8db63dfc94..429afcc480cb 100644 --- a/arch/s390/kernel/head.S +++ b/arch/s390/kernel/head.S @@ -437,7 +437,7 @@ ENTRY(startup_kdump) #if defined(CONFIG_64BIT) #if defined(CONFIG_MARCH_ZEC12) - .long 3, 0xc100efe3, 0xf46ce000, 0x00400000 + .long 3, 0xc100efe3, 0xf46ce800, 0x00400000 #elif defined(CONFIG_MARCH_Z196) .long 2, 0xc100efe3, 0xf46c0000 #elif defined(CONFIG_MARCH_Z10) |