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

* 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