1/* SPDX-License-Identifier: GPL-2.0-only */
2
3#include <linux/export.h>
4#include <linux/linkage.h>
5#include <asm/percpu.h>
6#include <asm/processor-flags.h>
7
8.text
9
10#ifndef CONFIG_X86_CMPXCHG64
11
12/*
13 * Emulate 'cmpxchg8b (%esi)' on UP
14 *
15 * Inputs:
16 * %esi : memory location to compare
17 * %eax : low 32 bits of old value
18 * %edx : high 32 bits of old value
19 * %ebx : low 32 bits of new value
20 * %ecx : high 32 bits of new value
21 */
22SYM_FUNC_START(cmpxchg8b_emu)
23
24 pushfl
25 cli
26
27 cmpl 0(%esi), %eax
28 jne .Lnot_same
29 cmpl 4(%esi), %edx
30 jne .Lnot_same
31
32 movl %ebx, 0(%esi)
33 movl %ecx, 4(%esi)
34
35 orl $X86_EFLAGS_ZF, (%esp)
36
37 popfl
38 RET
39
40.Lnot_same:
41 movl 0(%esi), %eax
42 movl 4(%esi), %edx
43
44 andl $(~X86_EFLAGS_ZF), (%esp)
45
46 popfl
47 RET
48
49SYM_FUNC_END(cmpxchg8b_emu)
50EXPORT_SYMBOL(cmpxchg8b_emu)
51
52#endif
53
54#ifndef CONFIG_UML
55
56SYM_FUNC_START(this_cpu_cmpxchg8b_emu)
57
58 pushfl
59 cli
60
61 cmpl PER_CPU_VAR(0(%esi)), %eax
62 jne .Lnot_same2
63 cmpl PER_CPU_VAR(4(%esi)), %edx
64 jne .Lnot_same2
65
66 movl %ebx, PER_CPU_VAR(0(%esi))
67 movl %ecx, PER_CPU_VAR(4(%esi))
68
69 orl $X86_EFLAGS_ZF, (%esp)
70
71 popfl
72 RET
73
74.Lnot_same2:
75 movl PER_CPU_VAR(0(%esi)), %eax
76 movl PER_CPU_VAR(4(%esi)), %edx
77
78 andl $(~X86_EFLAGS_ZF), (%esp)
79
80 popfl
81 RET
82
83SYM_FUNC_END(this_cpu_cmpxchg8b_emu)
84
85#endif
86

source code of linux/arch/x86/lib/cmpxchg8b_emu.S