Re: [Qemu-devel] [PATCH] linux-user/signal.c: Use frame->retcode instead of frame address for alpha target restorer

[Richard Henderson <rth@twiddle.net>]

On 03/29/2016 07:25 AM, Laurent Vivier wrote:
> 
> 
> Le 29/03/2016 16:01, chengang@emindsoft.com.cn a écrit :
>> From: Chen Gang <chengang@emindsoft.com.cn>
>>
>> The restorer needs the return code address which is frame->retcode, not
>> frame itself.
>>
>> Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
>> ---
>>  linux-user/signal.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/linux-user/signal.c b/linux-user/signal.c
>> index e487f9e..4157154 100644
>> --- a/linux-user/signal.c
>> +++ b/linux-user/signal.c
>> @@ -5455,7 +5455,7 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
>>                     &frame->retcode[1]);
>>          __put_user(INSN_CALLSYS, &frame->retcode[2]);
>>          /* imb(); */
>> -        r26 = frame_addr;
>> +        r26 = frame_addr + offsetof(struct target_rt_sigframe, retcode);
>>      }
>>  
>>      if (err) {
>>
> 
> If you change setup_rt_frame(), you must update setup_frame() too.
> 
> It seems correct.
> 
> Richard, as you have written the original code, could you check this is
> correct?

Yes, it's correct, and yes both functions need fixing.

In practice, this path is historical and will never be used;
it was now a very old glibc that didn't supply a restorer.


r~