Re: [Qemu-devel] [PATCH 11/11] target/hppa: call eval_interrupt() after ssm

[Richard Henderson]

On 3/12/19 11:44 AM, Sven Schnelle wrote:
>> ... except what we're already doing that.  So I don't see what
>> can be changed to help.  This doesn't seem to make a difference.
> 
> I looked into this again, and with my limited TCG knowledge it looks like the
> exit_tb is not happening because ssm is called in a branch delay slot:
> 
> This is the TB it's calling when it looses the timer interrupt:
> 
> IN: 
> 0x0000000000045758:  bv r0(rp)
> 0x000000000004575c:  ssm 1,r0
> 
> OP:
>  ld_i32 tmp0,env,$0xffffffffffffffe0
>  movi_i32 tmp1,$0x0
>  brcond_i32 tmp0,tmp1,lt,$L0
> 
>  ---- 0000000000045758 000000000004575c
>  mov_i32 tmp0,r2
>  mov_i32 iaoq_b,tmp0
> 
>  ---- 000000000004575c 00000000ffffffff
>  movi_i32 tmp1,$0x4
>  add_i32 tmp0,iaoq_b,tmp1
>  ld_i32 tmp1,env,$0x1c0
>  movi_i32 tmp2,$0x1
>  or_i32 tmp1,tmp1,tmp2
>  call swap_system_mask,$0x1,$1,tmp1,env,tmp1
> 
> Everything above is ssm, and below this is the branch instruction, which skips
> the exit_tb (i think):
> 
>  mov_i32 iaoq_f,iaoq_b
>  mov_i32 iaoq_b,tmp0
>  mov_i64 iasq_f,iasq_b
>  call lookup_tb_ptr,$0x6,$1,tmp3,env
>  goto_ptr tmp3
>  set_label $L0
>  exit_tb $0x7f373c33cb83
> 
> I might also be totally wrong, let me know if that's the case. ;-)

You are absolutely correct.  Thanks for the failing code sequence; now I know
where to look.


r~