Re: [qemu-s390x] [Qemu-devel] [BUG] I/O thread segfault for QEMU on s390x

[Peter Maydell]

On 5 March 2018 at 18:54, Christian Borntraeger <address@hidden> wrote:
>
>
> On 03/05/2018 07:45 PM, Farhan Ali wrote:
>>    0x000003ff90752026 <+110>:    svc    175
>
> sys_rt_sigprocmask. r0 should not be changed by the system call.
>
>>    0x000003ff90752028 <+112>:    lgr    %r5,%r0
>> => 0x000003ff9075202c <+116>:    lfpc    248(%r5)
>
> so r5 is zero and it was loaded from r0. r0 was loaded from r3 (which is the 
> 2nd parameter to this
> function). Now this is odd.

...particularly given that the only place we call swapcontext()
the second parameter is always the address of a local variable
and can't be 0...

thanks
-- PMM