Re: [PATCH v2 19/41] hw/core: Add TCGCPUOps.record_sigsegv

[Philippe Mathieu-Daudé]

On 9/19/21 20:22, Philippe Mathieu-Daudé wrote:
> On 9/18/21 20:45, Richard Henderson wrote:
>> Add a new user-only interface for updating cpu state before
>> raising a signal.  This will replace tlb_fill for user-only
>> and should result in less boilerplate for each guest.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>  include/hw/core/tcg-cpu-ops.h | 26 ++++++++++++++++++++++++++
>>  1 file changed, 26 insertions(+)
>>
>> diff --git a/include/hw/core/tcg-cpu-ops.h b/include/hw/core/tcg-cpu-ops.h
>> index 4a4c4053e3..e229a40772 100644
>> --- a/include/hw/core/tcg-cpu-ops.h
>> +++ b/include/hw/core/tcg-cpu-ops.h
>> @@ -114,6 +114,32 @@ struct TCGCPUOps {
>>       */
>>      bool (*io_recompile_replay_branch)(CPUState *cpu,
>>                                         const TranslationBlock *tb);
>> +#else
>> +    /**
>> +     * record_sigsegv:
>> +     * @cpu: cpu context
>> +     * @addr: faulting guest address
>> +     * @access_type: access was read/write/execute
>> +     * @maperr: true for invalid page, false for permission fault
>> +     * @ra: host pc for unwinding
>> +     *
>> +     * We are about to raise SIGSEGV with si_code set for @maperr,
>> +     * and si_addr set for @addr.  Record anything further needed
>> +     * for the signal ucontext_t.
>> +     *
>> +     * If the emulated kernel does not provide anything to the signal
>> +     * handler with anything besides the user context registers, and
>> +     * the siginfo_t, then this hook need do nothing and may be omitted.
>> +     * Otherwise, record the data and return; the caller will raise
>> +     * the signal, unwind the cpu state, and return to the main loop.
>> +     *
>> +     * If it is simpler to re-use the sysemu tlb_fill code, @ra is provided
>> +     * so that a "normal" cpu exception can be raised.  In this case,
>> +     * the signal must be raised by the architecture cpu_loop.
>> +     */
> 
> Shouldn't it have the QEMU_NORETURN attribute?

Eh now I saw the next patch and understood raise_sigsegv() is
where QEMU_NORETURN belong :)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> 
>> +    void (*record_sigsegv)(CPUState *cpu, vaddr addr,
>> +                           MMUAccessType access_type,
>> +                           bool maperr, uintptr_t ra);
>>  #endif /* CONFIG_SOFTMMU */
>>  #endif /* NEED_CPU_H */
>>  
>>
> 
>