Re: [PATCH] target/avr: Ignore unimplemented WDR opcode

[Laurent Vivier]

Le 13/05/2021 à 19:04, Philippe Mathieu-Daudé a écrit :
> Cc'ing qemu-trivial@

Applied to my trivial-patches branch.

Thanks,
Laurent

> On 5/5/21 3:35 PM, Fred Konrad wrote:
>> Le 5/2/21 à 9:09 PM, Philippe Mathieu-Daudé a écrit :
>>> Running the WDR opcode triggers a segfault:
>>>
>>>    $ cat > foo.S << EOF
>>>    > __start:
>>>    >     wdr
>>>    > EOF
>>>    $ avr-gcc -nostdlib -nostartfiles -mmcu=avr6 foo.S -o foo.elf
>>>    $ qemu-system-avr -serial mon:stdio -nographic -no-reboot \
>>>      -M mega -bios foo.elf -d in_asm --singlestep
>>>    IN:
>>>    0x00000000:  WDR
>>>    Segmentation fault (core dumped)
>>>
>>>    (gdb) bt
>>>       #0  0x00005555add0b23a in gdb_get_cpu_pid (cpu=0x5555af5a4af0)
>>> at ../gdbstub.c:718
>>>       #1  0x00005555add0b2dd in gdb_get_cpu_process
>>> (cpu=0x5555af5a4af0) at ../gdbstub.c:743
>>>       #2  0x00005555add0e477 in gdb_set_stop_cpu (cpu=0x5555af5a4af0)
>>> at ../gdbstub.c:2742
>>>       #3  0x00005555adc99b96 in cpu_handle_guest_debug
>>> (cpu=0x5555af5a4af0) at ../softmmu/cpus.c:306
>>>       #4  0x00005555adcc66ab in rr_cpu_thread_fn (arg=0x5555af5a4af0)
>>> at ../accel/tcg/tcg-accel-ops-rr.c:224
>>>       #5  0x00005555adefaf12 in qemu_thread_start
>>> (args=0x5555af5d9870) at ../util/qemu-thread-posix.c:521
>>>       #6  0x00007f692d940ea5 in start_thread () from
>>> /lib64/libpthread.so.0
>>>       #7  0x00007f692d6699fd in clone () from /lib64/libc.so.6
>>>
>>> Since the watchdog peripheral is not implemented, simply
>>> log the opcode as unimplemented and keep going.
>>>
>>> Reported-by: Fred Konrad <konrad@adacore.com>
>>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>>> ---
>>>   target/avr/helper.c | 6 +-----
>>>   1 file changed, 1 insertion(+), 5 deletions(-)
>>>
>>> diff --git a/target/avr/helper.c b/target/avr/helper.c
>>> index 35e10195940..981c29da453 100644
>>> --- a/target/avr/helper.c
>>> +++ b/target/avr/helper.c
>>> @@ -188,11 +188,7 @@ void helper_break(CPUAVRState *env)
>>>     void helper_wdr(CPUAVRState *env)
>>>   {
>>> -    CPUState *cs = env_cpu(env);
>>> -
>>> -    /* WD is not implemented yet, placeholder */
>>> -    cs->exception_index = EXCP_DEBUG;
>>> -    cpu_loop_exit(cs);
>>> +    qemu_log_mask(LOG_UNIMP, "WDG reset (not implemented)\n");
>>>   }
>>
>> Seems ok to me, at least better than having a segfault.
>>
>> Reviewed-by: KONRAD Frederic <frederic.konrad@adacore.com>
>>
>>>     /*
>>>
>>
>