linux/arch/x86/lib/cmpxchg16b_emu.S
Jan Beulich 3f63572187 x86: Improve cmpxchg16b_emu.S
- don't include unneeded headers
- don't open-code PER_CPU_VAR()
- drop redundant entry point label
- complete unwind annotations
- use .L prefix on local label to not clutter the symbol table

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/542290BC020000780003807D@mail.emea.novell.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-10-08 10:05:49 +02:00

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/dwarf2.h>
#include <asm/percpu.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).
#
pushfq_cfi
cli
cmpq PER_CPU_VAR((%rsi)), %rax
jne .Lnot_same
cmpq PER_CPU_VAR(8(%rsi)), %rdx
jne .Lnot_same
movq %rbx, PER_CPU_VAR((%rsi))
movq %rcx, PER_CPU_VAR(8(%rsi))
CFI_REMEMBER_STATE
popfq_cfi
mov $1, %al
ret
CFI_RESTORE_STATE
.Lnot_same:
popfq_cfi
xor %al,%al
ret
CFI_ENDPROC
ENDPROC(this_cpu_cmpxchg16b_emu)