Re: [PATCH 2/2] tests/tcg: Add multiarch test for Xfer:siginfo:read stub

[Richard Henderson <richard.henderson@linaro.org>]

On 3/7/24 07:50, Gustavo Romero wrote:
> Hi Richard,
> 
> On 3/4/24 7:51 PM, Richard Henderson wrote:
>> On 3/4/24 10:59, Gustavo Romero wrote:
>>>> Perhaps just abort for SIGABRT instead?
>>>
>>> Although this can make a simpler test, the test can't control
>>> the si_addr value easily, which I think is interesting to be tested.
>>>
>>> Why do you prefer SIGABRT?
>>
>> I missed that you were testing si_addr -- in which case SIGSEGV is a good match.
>>
>>
>>>> A test using setitimer to raise SIGALRM would test the async path.
>>>
>>> SIGLARM doesn't generate any interesting siginfo?
>>
>> It should at minimum have si_sig = SIGALRM.
>>
>>>
>>> gromero@arm64:~$ gdb -q ./sigalrm
>>> Reading symbols from ./sigalrm...
>>> (gdb) run
>>> Starting program: /home/gromero/sigalrm
>>>
>>> Program terminated with signal SIGALRM, Alarm clock.
>>> The program no longer exists.
>>> (gdb) p $_siginfo
>>> $1 = void
>>
>> Well that's because the program died.
>> Do you need to have gdb handle the signal?
> 
> ouch, right :)
> 
> However, on a remote target, even if I catch that signal using
> 'catch signal SIGALRM' the GDBstub only closes the connection
> when SIGALRM is delivered. That's odd, I don't understand why.
> 
> I'm using the same binary that pretty much works on GDB locally.
> 
> 
> [Remote target]
> 
> gromero@arm64:~$ gdb -q
> gromero@arm64:~/qemu_tests$ gdb -q ./sigalrm
> Reading symbols from ./sigalrm...
> (gdb) catch signal SIGALRM
> Catchpoint 1 (signal SIGALRM)
> (gdb) c
> The program is not being run.
> (gdb) run
> Starting program: /home/gromero/qemu_tests/sigalrm
> [Inferior 1 (process 12732) exited normally]
> (gdb) quit
> 
> on the QEMU gdbstub side it reports "Alarm clock":
> 
> gromero@amd:~/git/qemu/build$ ./qemu-aarch64 -g 1234 ./sigalrm -s
> Alarm clock
> gromero@amd:~/git/qemu/build$
> 
> 
> [Locally]
> 
> gromero@arm64:~/qemu_tests$ gdb -q ./sigalrm
> Reading symbols from ./sigalrm...
> (gdb) catch signal SIGALRM
> Catchpoint 1 (signal SIGALRM)
> (gdb) run -s
> Starting program: /home/gromero/qemu_tests/sigalrm -s
> 
> Catchpoint 1 (signal SIGALRM), 0x000000000041a410 in ualarm ()
> (gdb) quit
> 
> 
> I'd like to add for the async path using SIGALRM but I need more
> time to understand what's going on regarding SIGLARM. I understand
> that's nothing wrong with the Xfer:siginfo:read stub itself, and
> because the main goal of the test is to test the stub, if you don't
> mind, I'd like to keep only the test with SIGSEGV for v2 and leave
> the async test as a follow-up.

Well that's certainly surprising.
Would you please file a bug report about this?
I think I know what the problem is, but let's track it anyway.


r~