Re: [PATCH v5] gdb: align siginfo_t with the Linux kernel definition

[Andrew Burgess <aburgess@redhat.com>]

Andrew Burgess <aburgess@redhat.com> writes:

> Matthieu Longo <matthieu.longo@arm.com> writes:
>
>> GDB's current definition of siginfo_t is missing many fields present in
>> the Linux kernel definition [1].
>>
>> These fields are useful for providing detailed, user-friendly diagnostics
>> when a fault occurs. Some new AArch64 extensions, such as Permission
>> Overlay Enhancement used to implement Protection Keys [2], require the
>> debugger to inspect 'si_pkey' alongside 'si_addr' to help the user identify
>> the problematic key.
>>
>> This patch aligns GDB's definition of the __sifields._sigfault member of
>> siginfo_t with the definition from the Linux kernel master branch.
>>
>> To avoid hardcoding the field access paths throughout the codebase, this
>> patch also introduces compile-time accessors for the siginfo_t attributes,
>> centralizing their definitions in a single location and making future
>> updates easier.
>>
>> Finally, extend the testsuite to verify access to the new si_pkey field
>> and its preservation when modifying $_siginfo and when reading core files.
>> The tests in siginfo-obj.exp rely on the siginfo_t definition provided by
>> glibc's <signal.h>, which does not yet expose all of the fields present in
>> the kernel definition. As a result, the tests cannot exercise every newly
>> added field and therefore focus on si_pkey, the field motivating this change.
>> The test validates that GDB can read and modify the field correctly; it does
>> not attempt to generate a real protection-key fault.
>
> Hi Matthieu,
>
> Please see this message:
>
>   https://sourceware.org/pipermail/bunsen/2026q3/001504.html
>
> This is an LLM generated analysis of this patch which makes the claim
> that si_pkey is not accessible at the glibc level on every
> architecture.
>
> I tried on a couple of compiler farm boxes, but ran into some TCL
> version issues so wasn't able to actually make-check, but on a ppc box,
> if I try to compile gdb.base/siginfo-obj.c manually I get:
>
>   $ gcc -o siginfo-obj siginfo-obj.c
>   siginfo-obj.c: In function ‘handler’:
>   siginfo-obj.c:38:31: error: ‘siginfo_t’ has no member named ‘si_pkey’
>      unsigned int ssi_pkey = info->si_pkey;
>                                ^
>
> This test file did compile before commit 9c99987237dcaca0c6c493d6a.
>
> It would be great if you could take a look at this.  Should the si_pkey
> parts of the test be optional maybe?

Found some time to look at this again.  I suspect the compile farm
machine I tried is just old.  I tried a more up to date machine, and
this all compiled fine.

I suspect we're OK with this test just not working on older machines.

Sorry for the noise.

Thanks,
Andrew