assembly - 加载-获取/存储-释放和中断

Question

假设我有一个原子加载-修改-存储操作:

1:    ldaxr x8, [x9]
      orr x10, x8, #1
      stlxr w11, x10, [x9]
      cbnz w11, 1b

如果我理解正确的话，当这段代码在两个核心上执行时(访问相同的内存地址)，那么线程A会使用ldaxr锁定资源。线程 B 中的 STLxr 失败并重试操作，直到线程 A 释放锁。

但是，如果主线程中的 ldaxr 之后发生中断并且中断处理程序尝试访问相同的内存地址，会发生什么情况？是否会出现死锁或中断处理程序优先，并且主线程中的 STLxr 从中断返回时会失败？

Answer 1

主线程中的STLxr将会失败。
ldaxr 和 STLxr 是 Load-link/Store-conditional说明，它们是无锁的，用户必须准备好重复 LL/SC。

Whenever an address is read using a Load Exclusive instruction, it is marked as being for an exclusive access. If an address marked as exclusive is written to using a Store Exclusive instruction, it clears the exclusive status. An attempt to write to an address not marked as exclusive using a Store Exclusive instruction will not succeed. This enables software to detect if the contents of that address have been changed since the last time it was read.