----- On Jul 26, 2021, at 12:10 PM, Guo Ren guoren@xxxxxxxxxx wrote: > Hi Mathieu, > > Sorry for forgetting to CC you in the last patch, and that patch has > been merged into master which has the problem of syscall restart. > > I still want to keep rseq feature for csky, and implement the > RSEQ_SKIP_FASTPATH for self-test, it that okay? No, the RSEQ_SKIP_FASTPATH is the one special-case of test build which skips building rseq critical sections entirely. This leaves out any relevant testing of rseq per-se. With what we have in the upstream selftests, I expect this test configuration to abort at runtime because no slow-path fallbacks are available when the fastpath is disabled. The asm glue to test rseq user-space really needs to be implemented for any useful testing to be done here. Unless that asm glue is contributed, none of the rseq logic is actually tested on that architecture. Considering the extremely-hard-to-debug nature of races with a broken rseq kernel implementation, proper testing coverage is paramount, so I still recommend the revert unless the selftests user-space asm glue is contributed for C-Sky. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
