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sparc64: Make rwsems 64-bit.

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Basically tip-off the powerpc code, use a 64-bit type and atomic64_t
interfaces for the implementation.

This gets us off of the by-hand asm code I wrote, which frankly I
think probably ruins I-cache hit rates.

The idea was the keep the call chains less deep, but anything taking
the rw-semaphores probably is also calling other stuff and therefore
already has allocated a stack-frame.  So no real stack frame savings
ever.

Ben H. has posted patches to make powerpc use 64-bit too and with some
abstractions we can probably use a shared header file somewhere.

With suggestions from Sam Ravnborg.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2010-08-17 22:49:26 -07:00
parent b10f997bb0
commit 9b3bb86aca
4 changed files with 104 additions and 193 deletions
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2
arch/sparc/lib/Makefile
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@ -15,7 +15,7 @@ lib-$(CONFIG_SPARC32) += divdi3.o udivdi3.o
lib-$(CONFIG_SPARC32) += copy_user.o locks.o
lib-y += atomic_$(BITS).o
lib-$(CONFIG_SPARC32) += lshrdi3.o ashldi3.o
lib-y += rwsem_$(BITS).o
lib-$(CONFIG_SPARC32) += rwsem_32.o
lib-$(CONFIG_SPARC32) += muldi3.o bitext.o cmpdi2.o
lib-$(CONFIG_SPARC64) += copy_page.o clear_page.o bzero.o

163
arch/sparc/lib/rwsem_64.S
View File

@ -1,163 +0,0 @@
/* rwsem.S: RW semaphore assembler.
*
* Written by David S. Miller (davem@redhat.com), 2001.
* Derived from asm-i386/rwsem.h
*/
#include <asm/rwsem-const.h>
.section .sched.text, "ax"
.globl __down_read
__down_read:
1: lduw [%o0], %g1
add %g1, 1, %g7
cas [%o0], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 1b
add %g7, 1, %g7
cmp %g7, 0
bl,pn %icc, 3f
nop
2:
retl
nop
3:
save %sp, -192, %sp
call rwsem_down_read_failed
mov %i0, %o0
ret
restore
.size __down_read, .-__down_read
.globl __down_read_trylock
__down_read_trylock:
1: lduw [%o0], %g1
add %g1, 1, %g7
cmp %g7, 0
bl,pn %icc, 2f
mov 0, %o1
cas [%o0], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 1b
mov 1, %o1
2: retl
mov %o1, %o0
.size __down_read_trylock, .-__down_read_trylock
.globl __down_write
__down_write:
sethi %hi(RWSEM_ACTIVE_WRITE_BIAS), %g1
or %g1, %lo(RWSEM_ACTIVE_WRITE_BIAS), %g1
1:
lduw [%o0], %g3
add %g3, %g1, %g7
cas [%o0], %g3, %g7
cmp %g3, %g7
bne,pn %icc, 1b
cmp %g7, 0
bne,pn %icc, 3f
nop
2: retl
nop
3:
save %sp, -192, %sp
call rwsem_down_write_failed
mov %i0, %o0
ret
restore
.size __down_write, .-__down_write
.globl __down_write_trylock
__down_write_trylock:
sethi %hi(RWSEM_ACTIVE_WRITE_BIAS), %g1
or %g1, %lo(RWSEM_ACTIVE_WRITE_BIAS), %g1
1:
lduw [%o0], %g3
cmp %g3, 0
bne,pn %icc, 2f
mov 0, %o1
add %g3, %g1, %g7
cas [%o0], %g3, %g7
cmp %g3, %g7
bne,pn %icc, 1b
mov 1, %o1
2: retl
mov %o1, %o0
.size __down_write_trylock, .-__down_write_trylock
.globl __up_read
__up_read:
1:
lduw [%o0], %g1
sub %g1, 1, %g7
cas [%o0], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 1b
cmp %g7, 0
bl,pn %icc, 3f
nop
2: retl
nop
3: sethi %hi(RWSEM_ACTIVE_MASK), %g1
sub %g7, 1, %g7
or %g1, %lo(RWSEM_ACTIVE_MASK), %g1
andcc %g7, %g1, %g0
bne,pn %icc, 2b
nop
save %sp, -192, %sp
call rwsem_wake
mov %i0, %o0
ret
restore
.size __up_read, .-__up_read
.globl __up_write
__up_write:
sethi %hi(RWSEM_ACTIVE_WRITE_BIAS), %g1
or %g1, %lo(RWSEM_ACTIVE_WRITE_BIAS), %g1
1:
lduw [%o0], %g3
sub %g3, %g1, %g7
cas [%o0], %g3, %g7
cmp %g3, %g7
bne,pn %icc, 1b
sub %g7, %g1, %g7
cmp %g7, 0
bl,pn %icc, 3f
nop
2:
retl
nop
3:
save %sp, -192, %sp
call rwsem_wake
mov %i0, %o0
ret
restore
.size __up_write, .-__up_write
.globl __downgrade_write
__downgrade_write:
sethi %hi(RWSEM_WAITING_BIAS), %g1
or %g1, %lo(RWSEM_WAITING_BIAS), %g1
1:
lduw [%o0], %g3
sub %g3, %g1, %g7
cas [%o0], %g3, %g7
cmp %g3, %g7
bne,pn %icc, 1b
sub %g7, %g1, %g7
cmp %g7, 0
bl,pn %icc, 3f
nop
2:
retl
nop
3:
save %sp, -192, %sp
call rwsem_downgrade_wake
mov %i0, %o0
ret
restore
.size __downgrade_write, .-__downgrade_write