[PATCH v14 0/9] Add rseq extensible ABI support

[Mathieu Desnoyers]

On 2024-12-06 10:50, Michael Jeanson wrote:
> On 2024-11-21 14:08, Michael Jeanson wrote:
>> Introduced in Linux v6.3 the rseq extensible ABI [1] will allow adding
>> rseq features past the initial 32 bytes of the original ABI.
>>
>> While the rseq features in the latest kernel still fit within the
>> original ABI size, there are currently only 4 bytes left. It would thus
>> be a good time to add support for the extensible ABI so that when new
>> features are added, they are immediately available to GNU libc users.
>>
>> We use the ELF auxiliary vector to query the kernel for the size and
>> alignment of the rseq area, if this fails we default to the original
>> fixed size and alignment of '32' which the kernel will accept as a
>> compatibility mode with the original ABI.
>>
>> This makes the size of the rseq area variable and thus requires to
>> relocate it out of 'struct pthread'. We chose to move it after (in block
>> allocation order) the last TLS block inside the static TLS block
>> allocation. It required a fairly small modification to the TLS block
>> allocator and did not interfere with the main executable TLS block which
>> must always be the first block relative to the thread pointer.
>>
>> [1] https://lore.kernel.org/all/20221122203932.231377-4-mathieu.desnoyers@efficios.com/
> 
> Ping? I see the release date for 2.41 and I'm getting a bit nervous.

Florian, Carlos, DJ, what is missing to get this into 2.41 ?

Thanks,

Mathieu

> 
> Michael
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com