From 102b0d2daa97dae68d3eed54d8fe37a9cc38a892 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 11:13:47 +0200 Subject: Adding upstream version 2.8.0+dfsg. Signed-off-by: Daniel Baumann --- lib/locks/exclusive/aarch64/spinlock.S | 75 ++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 lib/locks/exclusive/aarch64/spinlock.S (limited to 'lib/locks/exclusive/aarch64/spinlock.S') diff --git a/lib/locks/exclusive/aarch64/spinlock.S b/lib/locks/exclusive/aarch64/spinlock.S new file mode 100644 index 0000000..e941b8a --- /dev/null +++ b/lib/locks/exclusive/aarch64/spinlock.S @@ -0,0 +1,75 @@ +/* + * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include + + .globl spin_lock + .globl spin_unlock + +#if USE_SPINLOCK_CAS +#if !ARM_ARCH_AT_LEAST(8, 1) +#error USE_SPINLOCK_CAS option requires at least an ARMv8.1 platform +#endif + +/* + * When compiled for ARMv8.1 or later, choose spin locks based on Compare and + * Swap instruction. + */ + +/* + * Acquire lock using Compare and Swap instruction. + * + * Compare for 0 with acquire semantics, and swap 1. If failed to acquire, use + * load exclusive semantics to monitor the address and enter WFE. + * + * void spin_lock(spinlock_t *lock); + */ +func spin_lock + mov w2, #1 +1: mov w1, wzr +2: casa w1, w2, [x0] + cbz w1, 3f + ldxr w1, [x0] + cbz w1, 2b + wfe + b 1b +3: + ret +endfunc spin_lock + +#else /* !USE_SPINLOCK_CAS */ + +/* + * Acquire lock using load-/store-exclusive instruction pair. + * + * void spin_lock(spinlock_t *lock); + */ +func spin_lock + mov w2, #1 + sevl +l1: wfe +l2: ldaxr w1, [x0] + cbnz w1, l1 + stxr w1, w2, [x0] + cbnz w1, l2 + ret +endfunc spin_lock + +#endif /* USE_SPINLOCK_CAS */ + +/* + * Release lock previously acquired by spin_lock. + * + * Use store-release to unconditionally clear the spinlock variable. + * Store operation generates an event to all cores waiting in WFE + * when address is monitored by the global monitor. + * + * void spin_unlock(spinlock_t *lock); + */ +func spin_unlock + stlr wzr, [x0] + ret +endfunc spin_unlock -- cgit v1.2.3