Re: [PATCH v5 0/2] gdb: Fix internal inferior calls through GNU IFUNCs

[Muhammad Kamran <muhammad.kamran@arm.com>]

On 16/08/2026 08:24, Kevin Buettner wrote:
> On Tue, 11 Aug 2026 13:12:17 +0000
> Muhammad Kamran <muhammad.kamran@arm.com> wrote:
> 
>> This series fixes a GDB inferior-call issue exposed by malloc being a GNU
>> IFUNC in glibc on AArch64.  The underlying problem is not AArch64-specific:
>> it can affect any inferior helper found through find_function_in_inferior's
>> minimal-symbol fallback when that helper is a GNU IFUNC.
>>
>> GDB calls find_function_in_inferior ("malloc") when expression evaluation
>> needs to allocate memory in the inferior, for example for string literal
>> arguments.  In the minimal-symbol fallback, GDB created a synthetic ordinary
>> function pointer from the minimal symbol address.  If the symbol was a GNU
>> IFUNC, this lost the IFUNC marker, so call_function_by_hand did not resolve
>> the symbol before calling it.
>>
>> Patch 1 checks the minimal symbol kind directly and propagates the GNU IFUNC
>> marker to the synthetic function type for mst_text_gnu_ifunc and
>> mst_data_gnu_ifunc symbols.  The existing fallback address and return type
>> are unchanged.
>>
>> Patch 2 fixes the follow-on return-type issue after IFUNC resolution.  When
>> the resolved target type, or the type inferred from the resolver return type,
>> does not provide a usable return type, find_function_addr now keeps the
>> original function type's return type.  This preserves the synthetic fallback
>> return type used by find_function_in_inferior ("malloc").
>>
>> The tests add an internal inferior-call case using an IFUNC malloc and run it
>> through the existing gdb.base/gnu-ifunc.exp matrix for resolver attr,
>> resolver debug info, and resolved-target debug info.
>>
>> Changes since v4:
>> 	* Address feedback from Andrew Burgess <aburgess@redhat.com>.
>>
>> Changes since v3:
>> 	* Move the ifunc resolver into a shared library.
>>
>> Changes since v2:
>> 	* Rework the minimal-symbol fallback to check the minimal symbol kind
>> 	  directly as suggested by Simon.
>> 	* Add coverage for both debug and no-debug IFUNC malloc variants by
>> 	  using the existing framework.
>> 	* Preserve the original IFUNC return type when the resolved target type
>> 	  is unknown.
> 
> Andrew gave conditional approval for both parts in his v4 replies.
> I've looked over this v5 series; IMO, you've completely addressed his
> concerns.  Therefore, I think you can consider this version approved;
> but do add Andrew's Approved-By tag.  If you need a maintainer to push
> it for you, I'll be happy to do that.

Hi Kevin,

Thanks for reviewing.

I don't have write access, so I'd appreciate it if you could please push
the series for me.

Andrew gave his Approved-By on both patches, so please feel free to add:

Approved-By: Andrew Burgess <aburgess@redhat.com>

Thanks,
Kamran

> 
> Reviewed-By: Kevin Buettner <kevinb@redhat.com>
>