----- On Jun 6, 2019, at 1:57 PM, Florian Weimer fweimer@xxxxxxxxxx wrote: > * Mathieu Desnoyers: > [...] > >>> The final remaining case is static dlopen. There is a copy of ld.so on >>> the dynamic side, but it is completely inactive and has never run. I do >>> not think we need to support that because multi-threading does not work >>> reliably in this scenario, either. However, we should skip rseq >>> registration in a nested libc (see the rtld_active function). >> >> So for SHARED, if (!rtld_active ()), we should indeed leave the state of >> __rseq_handled as it is, because we are within a nested inactive ld.so. > > I think we should add __rseq_handled initialization to ld.so, so it will > only run once, ever. OK > > It's the registration from libc.so which needs some care. In > particular, we must not override an existing registration. OK, so it could check if __rseq_abi.cpu_id is -1, and only perform registration if it is the case. Or do you have another approach in mind ? For the main thread, "nested" unregistration does not appear to be a problem, because we rely on program exit() to implicitly unregister. Thanks, Mathieu > > Thanks, > Florian -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
