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git.proxmox.com Git - mirror_qemu.git/blob - util/atomic64.c
2 * Copyright (C) 2018, Emilio G. Cota <cota@braap.org>
4 * License: GNU GPL, version 2 or later.
5 * See the COPYING file in the top-level directory.
7 #include "qemu/osdep.h"
8 #include "qemu/atomic.h"
9 #include "qemu/thread.h"
10 #include "qemu/cacheinfo.h"
11 #include "qemu/memalign.h"
13 #ifdef CONFIG_ATOMIC64
14 #error This file must only be compiled if !CONFIG_ATOMIC64
18 * When !CONFIG_ATOMIC64, we serialize both reads and writes with spinlocks.
19 * We use an array of spinlocks, with padding computed at run-time based on
20 * the host's dcache line size.
21 * We point to the array with a void * to simplify the padding's computation.
22 * Each spinlock is located every lock_size bytes.
24 static void *lock_array
;
25 static size_t lock_size
;
28 * Systems without CONFIG_ATOMIC64 are unlikely to have many cores, so we use a
29 * small array of locks.
33 static QemuSpin
*addr_to_lock(const void *addr
)
35 uintptr_t a
= (uintptr_t)addr
;
38 idx
= a
>> qemu_dcache_linesize_log
;
39 idx
^= (idx
>> 8) ^ (idx
>> 16);
41 return lock_array
+ idx
* lock_size
;
44 #define GEN_READ(name, type) \
45 type name(const type *ptr) \
47 QemuSpin *lock = addr_to_lock(ptr); \
50 qemu_spin_lock(lock); \
52 qemu_spin_unlock(lock); \
56 GEN_READ(qatomic_read_i64
, int64_t)
57 GEN_READ(qatomic_read_u64
, uint64_t)
60 #define GEN_SET(name, type) \
61 void name(type *ptr, type val) \
63 QemuSpin *lock = addr_to_lock(ptr); \
65 qemu_spin_lock(lock); \
67 qemu_spin_unlock(lock); \
70 GEN_SET(qatomic_set_i64
, int64_t)
71 GEN_SET(qatomic_set_u64
, uint64_t)
74 void qatomic64_init(void)
78 lock_size
= ROUND_UP(sizeof(QemuSpin
), qemu_dcache_linesize
);
79 lock_array
= qemu_memalign(qemu_dcache_linesize
, lock_size
* NR_LOCKS
);
80 for (i
= 0; i
< NR_LOCKS
; i
++) {
81 QemuSpin
*lock
= lock_array
+ i
* lock_size
;