----- 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: >> >> > ----- Gavin Shan <gshan@xxxxxxxxxx> wrote: >> >> Hi Florian, >> >> >> >> On 8/9/22 5:16 PM, Florian Weimer wrote: >> >> >>> __builtin_thread_pointer doesn't work on all architectures/GCC >> >> >>> versions. >> >> >>> Is this a problem for selftests? >> >> >>> >> >> >> >> >> >> It's a problem as the test case is running on all architectures. I think I >> >> >> need introduce our own __builtin_thread_pointer() for where it's not >> >> >> supported: (1) PowerPC (2) x86 without GCC 11 >> >> >> >> >> >> Please let me know if I still have missed cases where >> >> >> __buitin_thread_pointer() isn't supported? >> >> > >> >> > As far as I know, these are the two outliers that also have rseq >> >> > support. The list is a bit longer if we also consider non-rseq >> >> > architectures (csky, hppa, ia64, m68k, microblaze, sparc, don't know >> >> > about the Linux architectures without glibc support). >> >> > >> >> >> >> For kvm/selftests, there are 3 architectures involved actually. So we >> >> just need consider 4 cases: aarch64, x86, s390 and other. For other >> >> case, we just use __builtin_thread_pointer() to maintain code's >> >> integrity, but it's not called at all. >> >> >> >> I think kvm/selftest is always relying on glibc if I'm correct. >> > >> > 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 ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
