arm assembly mutex strex，ldrex

Question

首先感谢您观看我的问题并回复。

我在banana-pi m1上制作类似软件的操作系统。

这个平台是双皮质a-7。

我还实现了如下的互斥锁。

.global lock_mutex
lock_mutex:
    ldr     r1, =UNLOCKED
1:  ldrex   r2, [r0]
    cmp     r2, r1

    wfene                           @ wfe if locked

    read_cp32(r1, MPIDR)            @ MPIDR (ARMv7 only)
    strexne r2, r1, [r0]            @ Trying to lock
    cmpne   r2, #1                  @ if failed to lock acquire
    beq     1b                      @ branch to before 1 label if fail to lock

    dmb
    bx      lr

.global unlock_mutex                @ in the case of unlock, 
                                  @there's no need to check the status of lock
unlock_mutex:
    ldr     r1, =UNLOCKED
    dmb
    str     r1, [r0]                @ clear the lock
    dmb 
    sev                             @ sending the event to other processors that is wfe status
    bx      lr  

在＆＃34; ldrex r2，[r0]＆＃34;这条指令，什么都没发生，似乎cpu死了。

使用ldrex＆amp;之前有任何建议吗？ strex指令