mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-30 15:44:13 +08:00
b9ec40af0e
Support this_cpu_cmpxchg_double() using the cmpxchg16b and cmpxchg8b
instructions.
-tj: s/percpu_cmpxchg16b/percpu_cmpxchg16b_double/ for consistency and
other cosmetic changes.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
60 lines
1.2 KiB
ArmAsm
60 lines
1.2 KiB
ArmAsm
/*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; version 2
|
|
* of the License.
|
|
*
|
|
*/
|
|
#include <linux/linkage.h>
|
|
#include <asm/alternative-asm.h>
|
|
#include <asm/frame.h>
|
|
#include <asm/dwarf2.h>
|
|
|
|
.text
|
|
|
|
/*
|
|
* Inputs:
|
|
* %rsi : memory location to compare
|
|
* %rax : low 64 bits of old value
|
|
* %rdx : high 64 bits of old value
|
|
* %rbx : low 64 bits of new value
|
|
* %rcx : high 64 bits of new value
|
|
* %al : Operation successful
|
|
*/
|
|
ENTRY(this_cpu_cmpxchg16b_emu)
|
|
CFI_STARTPROC
|
|
|
|
#
|
|
# Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in %al not
|
|
# via the ZF. Caller will access %al to get result.
|
|
#
|
|
# Note that this is only useful for a cpuops operation. Meaning that we
|
|
# do *not* have a fully atomic operation but just an operation that is
|
|
# *atomic* on a single cpu (as provided by the this_cpu_xx class of
|
|
# macros).
|
|
#
|
|
this_cpu_cmpxchg16b_emu:
|
|
pushf
|
|
cli
|
|
|
|
cmpq %gs:(%rsi), %rax
|
|
jne not_same
|
|
cmpq %gs:8(%rsi), %rdx
|
|
jne not_same
|
|
|
|
movq %rbx, %gs:(%rsi)
|
|
movq %rcx, %gs:8(%rsi)
|
|
|
|
popf
|
|
mov $1, %al
|
|
ret
|
|
|
|
not_same:
|
|
popf
|
|
xor %al,%al
|
|
ret
|
|
|
|
CFI_ENDPROC
|
|
|
|
ENDPROC(this_cpu_cmpxchg16b_emu)
|