Re: [PATCH v4 05/10] signal: Introduce TRAP_PERF si_code and si_perf to siginfo

[Jon Hunter]

On 22/04/2021 07:47, Marco Elver wrote:
> On Thu, 22 Apr 2021 at 08:12, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:
> [...]
>>> So I think we just have to settle on 'unsigned long' here. On many
>>> architectures, like 32-bit Arm, the alignment of a structure is that of
>>> its largest member. This means that there is no portable way to add
>>> 64-bit integers to siginfo_t on 32-bit architectures.
>>>
>>> In the case of the si_perf field, word size is sufficient since the data
>>> it contains is user-defined. On 32-bit architectures, any excess bits of
>>> perf_event_attr::sig_data will therefore be truncated when copying into
>>> si_perf.
>>>
>>> Feel free to test the below if you have time, but the below lets me boot
>>> 32-bit arm which previously timed out. It also passes all the
>>> static_asserts() I added (will send those as separate patches).
>>>
>>> Once I'm convinced this passes all others tests too, I'll send a patch.
>>
>> This fixes the issue I've observed on my test systems. Feel free to add:
>>
>> Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
>>
>> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> 
> Thank you for testing! It's been sent:
> https://lkml.kernel.org/r/20210422064437.3577327-1-elver@xxxxxxxxxx


Thanks! This fixes the problem for Tegra as well. I have responded to
the above patch with my tested-by.

Cheers
Jon

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