Re: [PATCH 1/2] KVM: selftests: Make rseq compatible with glibc-2.35

[Gavin Shan]

Hi Mathieu,

On 8/10/22 10:13 PM, Mathieu Desnoyers wrote:
> ----- On Aug 9, 2022, at 5:38 PM, Sean Christopherson seanjc@xxxxxxxxxx wrote: 
> > On Tue, Aug 09, 2022, Mathieu Desnoyers wrote:
> > > ----- On Aug 9, 2022, at 8:21 AM, Mathieu Desnoyers
> > > mathieu.desnoyers@xxxxxxxxxxxx wrote:

[...]

> > > > All those are handled in the rseq selftests and in librseq. Why duplicate all
> > > > that logic again?
> > >
> > > More to the point, considering that we have all the relevant rseq registration
> > > code in tools/testing/selftests/rseq/rseq.c already, and the relevant thread
> > > pointer getter code in tools/testing/selftests/rseq/rseq-*thread-pointer.h,
> > > is there an easy way to get test applications in tools/testing/selftests/kvm
> > > and in tools/testing/selftests/rseq to share that common code ?
> > >
> > > Keeping duplicated compatibility code is bad for long-term maintainability.
> >
> > Any reason not to simply add tools/lib/rseq.c and then expose a helper to get
> > the
> > registered rseq struct?
>
> Indeed, moving rseq.c to tools/lib/ would allow building a .so from any selftest
> which needs to use it.
>
> And we could move the relevant rseq helper header files to tools/include/rseq/*
> as well.
>
> Thoughts ?

One question is how librseq.so can be built automatically, when I'm going to
build tools/testing/selftests/kvm/rseq_test.

    # cd linux/tools/testing/selftests/kvm
    # make rseq_test

It's not perfect if I have to build tools/lib/librseq.so in advance, in order
to build tools/testing/selftests/kvm/rseq_test for the sake of dependency.

Thanks,
Gavin