blob: d63185698a23f6d9ce75651f690669cea60e19d3 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
/* SPDX-License-Identifier: GPL-2.0-only */
#include <linux/linkage.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)
#
# 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
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))
popfq
mov $1, %al
ret
.Lnot_same:
popfq
xor %al,%al
ret
ENDPROC(this_cpu_cmpxchg16b_emu)
|
