Re: [RFC PATCH] rseq: x86: implement abort-at-ip extension

[Florian Weimer]

* Mathieu Desnoyers:

> Allow rseq critical section abort handlers to optionally figure out at
> which instruction pointer the rseq critical section was aborted.
>
> This allows implementing rseq critical sections containing loops, in
> which case the commit side-effect cannot be the last instruction. This
> is useful to implement adaptative mutexes aware of preemption in
> user-space. (see [1])

Could you write the program counter to the rseq area instead?  This
would avoid discussing which register to clobber.

Thanks,
Florian