d7c3f8cee8
Omit the segment prefix in the UP case. GS is not used then and we will generate segfaults if cmpxchg16b is used otherwise. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
65 lines
1.3 KiB
ArmAsm
65 lines
1.3 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>
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define SEG_PREFIX %gs:
|
|
#else
|
|
#define SEG_PREFIX
|
|
#endif
|
|
|
|
.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 SEG_PREFIX(%rsi), %rax
|
|
jne not_same
|
|
cmpq SEG_PREFIX 8(%rsi), %rdx
|
|
jne not_same
|
|
|
|
movq %rbx, SEG_PREFIX(%rsi)
|
|
movq %rcx, SEG_PREFIX 8(%rsi)
|
|
|
|
popf
|
|
mov $1, %al
|
|
ret
|
|
|
|
not_same:
|
|
popf
|
|
xor %al,%al
|
|
ret
|
|
|
|
CFI_ENDPROC
|
|
|
|
ENDPROC(this_cpu_cmpxchg16b_emu)
|