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feat(locks): add bitlock

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This patch adds 'bitlock_t' type and bit_lock() and
bit_unlock() to support locking/release functionality
based on individual bit position. These functions use
atomic bit set and clear instructions which require
FEAT_LSE mandatory from Armv8.1.

Change-Id: I3eb0f29bbccefe6c0f69061aa701187a6364df0c
Signed-off-by: AlexeiFedorov <Alexei.Fedorov@arm.com>
This commit is contained in:
AlexeiFedorov 2024-03-13 12:16:51 +00:00
parent 7d5fc98f54
commit 222f885df3
2 changed files with 52 additions and 4 deletions
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12
include/lib/spinlock.h
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2013-2018, Arm Limited and Contributors. All rights reserved.
* Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@ -15,15 +15,21 @@ typedef struct spinlock {
volatile uint32_t lock;
} spinlock_t;
typedef struct bitlock {
volatile uint8_t lock;
} bitlock_t;
void spin_lock(spinlock_t *lock);
void spin_unlock(spinlock_t *lock);
void bit_lock(bitlock_t *lock, uint8_t mask);
void bit_unlock(bitlock_t *lock, uint8_t mask);
#else
/* Spin lock definitions for use in assembly */
#define SPINLOCK_ASM_ALIGN 2
#define SPINLOCK_ASM_SIZE 4
#endif
#endif /* __ASSEMBLER__ */
#endif /* SPINLOCK_H */

44
lib/locks/exclusive/aarch64/spinlock.S
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2013-2019, Arm Limited and Contributors. All rights reserved.
* Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@ -8,6 +8,8 @@
.globl spin_lock
.globl spin_unlock
.globl bit_lock
.globl bit_unlock
#if USE_SPINLOCK_CAS
#if !ARM_ARCH_AT_LEAST(8, 1)
@ -73,3 +75,43 @@ func spin_unlock
stlr wzr, [x0]
ret
endfunc spin_unlock
/*
* Atomic bit clear and set instructions require FEAT_LSE which is
* mandatory from Armv8.1.
*/
#if ARM_ARCH_AT_LEAST(8, 1)
/*
* Acquire bitlock using atomic bit set on byte. If the original read value
* has the bit set, use load exclusive semantics to monitor the address and
* enter WFE.
*
* void bit_lock(bitlock_t *lock, uint8_t mask);
*/
func bit_lock
1: ldsetab w1, w2, [x0]
tst w2, w1
b.eq 2f
ldxrb w2, [x0]
tst w2, w1
b.eq 1b
wfe
b 1b
2:
ret
endfunc bit_lock
/*
* Use atomic bit clear store-release to unconditionally clear bitlock variable.
* Store operation generates an event to all cores waiting in WFE when address
* is monitored by the global monitor.
*
* void bit_unlock(bitlock_t *lock, uint8_t mask);
*/
func bit_unlock
stclrlb w1, [x0]
ret
endfunc bit_unlock
#endif /* ARM_ARCH_AT_LEAST(8, 1) */