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

[Florian Weimer]

* Mathieu Desnoyers:

> So indeed it could be done today without upgrading the toolchains by
> writing custom assembler for each architecture to get the thread's
> struct rseq. AFAIU the ABI to access the thread pointer is fixed for
> each architecture, right ?

Yes, determining the thread pointer and access initial-exec TLS
variables is baked into the ABI.

> 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.

Thanks,
Florian