diff options
Diffstat (limited to 'lib/locks/exclusive/aarch32/spinlock.S')
| -rw-r--r-- | lib/locks/exclusive/aarch32/spinlock.S | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/lib/locks/exclusive/aarch32/spinlock.S b/lib/locks/exclusive/aarch32/spinlock.S new file mode 100644 index 0000000..853d096 --- /dev/null +++ b/lib/locks/exclusive/aarch32/spinlock.S @@ -0,0 +1,43 @@ +/* + * Copyright (c) 2016, Arm Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include <asm_macros.S> + + .globl spin_lock + .globl spin_unlock + +#if ARM_ARCH_AT_LEAST(8, 0) +/* + * According to the ARMv8-A Architecture Reference Manual, "when the global + * monitor for a PE changes from Exclusive Access state to Open Access state, + * an event is generated.". This applies to both AArch32 and AArch64 modes of + * ARMv8-A. As a result, no explicit SEV with unlock is required. + */ +#define COND_SEV() +#else +#define COND_SEV() sev +#endif + +func spin_lock + mov r2, #1 +1: + ldrex r1, [r0] + cmp r1, #0 + wfene + strexeq r1, r2, [r0] + cmpeq r1, #0 + bne 1b + dmb + bx lr +endfunc spin_lock + + +func spin_unlock + mov r1, #0 + stl r1, [r0] + COND_SEV() + bx lr +endfunc spin_unlock |