Re: [RFC PATCH 2/4] rseq: Allow extending struct rseq

[Mathieu Desnoyers]

----- On Jul 15, 2020, at 9:42 AM, Florian Weimer fweimer@xxxxxxxxxx wrote:
> * Mathieu Desnoyers:
> 
[...]
>> How would this allow early-rseq-adopter libraries to interact with
>> glibc ?
> 
> Under all extension proposals I've seen so far, early adopters are
> essentially incompatible with glibc rseq registration.  I don't think
> you can have it both ways.

The basic question I'm not sure about is whether we are allowed to increase
the size and alignement of __rseq_abi from e.g. glibc 2.32 to glibc 2.33.
If not, then we just need to find another way to extend struct rseq, e.g. by
adding a pointer to another extended structure in the padding space we
have at the end of struct rseq.

Thanks,

Mathieu

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