| /* |
| * Copyright (C) 2018, Emilio G. Cota <cota@braap.org> |
| * |
| * License: GNU GPL, version 2 or later. |
| * See the COPYING file in the top-level directory. |
| */ |
| #include "qemu/osdep.h" |
| #include "qemu/atomic.h" |
| #include "qemu/thread.h" |
| |
| #ifdef CONFIG_ATOMIC64 |
| #error This file must only be compiled if !CONFIG_ATOMIC64 |
| #endif |
| |
| /* |
| * When !CONFIG_ATOMIC64, we serialize both reads and writes with spinlocks. |
| * We use an array of spinlocks, with padding computed at run-time based on |
| * the host's dcache line size. |
| * We point to the array with a void * to simplify the padding's computation. |
| * Each spinlock is located every lock_size bytes. |
| */ |
| static void *lock_array; |
| static size_t lock_size; |
| |
| /* |
| * Systems without CONFIG_ATOMIC64 are unlikely to have many cores, so we use a |
| * small array of locks. |
| */ |
| #define NR_LOCKS 16 |
| |
| static QemuSpin *addr_to_lock(const void *addr) |
| { |
| uintptr_t a = (uintptr_t)addr; |
| uintptr_t idx; |
| |
| idx = a >> qemu_dcache_linesize_log; |
| idx ^= (idx >> 8) ^ (idx >> 16); |
| idx &= NR_LOCKS - 1; |
| return lock_array + idx * lock_size; |
| } |
| |
| #define GEN_READ(name, type) \ |
| type name(const type *ptr) \ |
| { \ |
| QemuSpin *lock = addr_to_lock(ptr); \ |
| type ret; \ |
| \ |
| qemu_spin_lock(lock); \ |
| ret = *ptr; \ |
| qemu_spin_unlock(lock); \ |
| return ret; \ |
| } |
| |
| GEN_READ(atomic_read_i64, int64_t) |
| GEN_READ(atomic_read_u64, uint64_t) |
| #undef GEN_READ |
| |
| #define GEN_SET(name, type) \ |
| void name(type *ptr, type val) \ |
| { \ |
| QemuSpin *lock = addr_to_lock(ptr); \ |
| \ |
| qemu_spin_lock(lock); \ |
| *ptr = val; \ |
| qemu_spin_unlock(lock); \ |
| } |
| |
| GEN_SET(atomic_set_i64, int64_t) |
| GEN_SET(atomic_set_u64, uint64_t) |
| #undef GEN_SET |
| |
| void atomic64_init(void) |
| { |
| int i; |
| |
| lock_size = ROUND_UP(sizeof(QemuSpin), qemu_dcache_linesize); |
| lock_array = qemu_memalign(qemu_dcache_linesize, lock_size * NR_LOCKS); |
| for (i = 0; i < NR_LOCKS; i++) { |
| QemuSpin *lock = lock_array + i * lock_size; |
| |
| qemu_spin_init(lock); |
| } |
| } |