riscv virt64 trap_entry 问题

发布于 2024-09-25 16:07:56 浏览：75 订阅该版

```c
trap_entry:
    // distingush exception from kernel or user
    csrrw   sp, sscratch, sp
    bnez    sp, _save_context

// BE REALLY careful with sscratch,
    // if it's wrong, we could looping here forever
    // or accessing random memory and seeing things totally
    // messy after a long time and don't even know why
_from_kernel:
    csrr    sp, sscratch
    j _save_context

_save_context:
    SAVE_ALL
    // clear sscratch to say 'now in kernel mode'
    csrw    sscratch, zero

RESTORE_SYS_GP

// now we are ready to enter interrupt / excepiton handler
_distinguish_syscall:
    csrr    t0, scause
#ifdef RT_USING_SMART
    // TODO swap 8 with config macro name
    li      t1, 8
    beq     t0, t1, syscall_entry
    // syscall never return here
#endif

_handle_interrupt_and_exception:
    mv      a0, t0
    csrrc   a1, stval, zero
    csrr    a2, sepc
    // sp as exception frame pointer
    mv      a3, sp
    call    handle_trap

_interrupt_exit:
    la      s0, rt_thread_switch_interrupt_flag
    lw      s2, 0(s0)
    beqz    s2, _resume_execution
    sw      zero, 0(s0)

_context_switch:   // 请问这里如果 进行了上下文切换， 15 行的 saveall不就无法恢复，导致内存泄露了吗？？？？？？？？？？？？？？？
    la      t0, rt_interrupt_from_thread
    LOAD    a0, 0(t0)
    la      t0, rt_interrupt_to_thread
    LOAD    a1, 0(t0)
    jal     rt_hw_context_switch
```

请问如果中断服务程序是唤醒另一个线程， 
```
rt_thread_switch_interrupt_flag = 1， 
```
直接进行 `_context_switch`, 不就导致 15 行 save_all 无法恢复了，产生了内存泄露吗？