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
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/*
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
#include <asm/lse.h>
#include <asm/spinlock_types.h>
#include <asm/processor.h>
/*
* Spinlock implementation.
*
* The memory barriers are implicit with the load-acquire and store-release
* instructions.
*/
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
unsigned int tmp;
arch_spinlock_t lockval, newval;
asm volatile(
/* Atomically increment the next ticket. */
ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" prfm pstl1strm, %3\n"
"1: ldaxr %w0, %3\n"
" add %w1, %w0, %w5\n"
" stxr %w2, %w1, %3\n"
" cbnz %w2, 1b\n",
/* LSE atomics */
" mov %w2, %w5\n"
" ldadda %w2, %w0, %3\n"
__nops(3)
)
/* Did we get the lock? */
" eor %w1, %w0, %w0, ror #16\n"
" cbz %w1, 3f\n"
/*
* No: spin on the owner. Send a local event to avoid missing an
* unlock before the exclusive load.
*/
" sevl\n"
"2: wfe\n"
" ldaxrh %w2, %4\n"
" eor %w1, %w2, %w0, lsr #16\n"
" cbnz %w1, 2b\n"
/* We got the lock. Critical section starts here. */
"3:"
: "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*lock)
: "Q" (lock->owner), "I" (1 << TICKET_SHIFT)
: "memory");
}
static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
unsigned int tmp;
arch_spinlock_t lockval;
asm volatile(ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" prfm pstl1strm, %2\n"
"1: ldaxr %w0, %2\n"
" eor %w1, %w0, %w0, ror #16\n"
" cbnz %w1, 2f\n"
" add %w0, %w0, %3\n"
" stxr %w1, %w0, %2\n"
" cbnz %w1, 1b\n"
"2:",
/* LSE atomics */
" ldr %w0, %2\n"
" eor %w1, %w0, %w0, ror #16\n"
" cbnz %w1, 1f\n"
" add %w1, %w0, %3\n"
" casa %w0, %w1, %2\n"
" sub %w1, %w1, %3\n"
" eor %w1, %w1, %w0\n"
"1:")
: "=&r" (lockval), "=&r" (tmp), "+Q" (*lock)
: "I" (1 << TICKET_SHIFT)
: "memory");
return !tmp;
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
unsigned long tmp;
asm volatile(ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" ldrh %w1, %0\n"
" add %w1, %w1, #1\n"
" stlrh %w1, %0",
/* LSE atomics */
" mov %w1, #1\n"
" staddlh %w1, %0\n"
__nops(1))
: "=Q" (lock->owner), "=&r" (tmp)
:
: "memory");
}
static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
{
return lock.owner == lock.next;
}
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
return !arch_spin_value_unlocked(READ_ONCE(*lock));
}
static inline int arch_spin_is_contended(arch_spinlock_t *lock)
{
arch_spinlock_t lockval = READ_ONCE(*lock);
return (lockval.next - lockval.owner) > 1;
}
#define arch_spin_is_contended arch_spin_is_contended
#include <asm/qrwlock.h>
/* See include/linux/spinlock.h */
#define smp_mb__after_spinlock() smp_mb()
#endif /* __ASM_SPINLOCK_H */
|
