It is interesting that the stop reason on the thread that stopped is "trace". That's what you would expect returning from the single-step to step over the breakpoint. But it looks like we got a signal while single-stepping, but the stop reason was misreported by somebody.
Jim > On Apr 17, 2018, at 6:00 AM, Pavel Labath via lldb-dev > <lldb-dev@lists.llvm.org> wrote: > > [+lldb-dev] > > Hello Steve, > > thanks for the report. > > The fact that you see the rendezvous breakpoint being hit many times is not > surprising. We get those every time the library is loaded (we need that to > load relevant debug info and set potential breakpoints). However, they > should generally not be surfaced to the user (unless you have the > stop-on-sharedlibrary-events setting set, which you don't). > > The part that is suspicious to me is that __restore_rt shows up on the top > of the backtrace. This is a trampoline used to return from signal handlers, > and it would seem to indicate that you got some sort of a signal while > loading the libraries. I don't know why this would happen, but it could be > that this is confusing lldb's auto-resume logic. > > The interesting part to see here is what lldb thinks are the stop reasons > for individual threads in the process (is the process multi-threaded?) for > the last couple of stops. The "lldb step" and "gdb-remote packets" log > categories are the most interesting to observe here. If you are able to > send me the log traces, I can help you interpret them. > > regards, > pavel > > > > > > On Tue, 17 Apr 2018 at 02:27, Steve Ravet via llvm-dev < > llvm-...@lists.llvm.org> wrote: > >> Hello lldb developers, I am running into a problem with lldb on Linux. I > am currently running llvm 6.0.0. > >> I have an executable that dynamically loads a large number of shared > libraries at runtime. These are explicitly loaded via dlopen (they are > specified in a configuration file), and after loading a few (typically a > dozen or so, but the number varies) lldb will halt during dlopen. If I > continue, it will load a few more then halt again, which makes debugging > from startup impractical since there are so many libraries to be loaded > (more than a hundred of them). > >> When I build and debug this same C++ on macOS, the debugger works fine. > I have verified that target.process.stop-on-sharedlibrary-events is false. > I turned on dyld logging and I see lots of log messages about > RendezvousBreakpoint being hit, but I don’t see anything that sheds light > on why some libraries load without stopping but others don’t. > >> I have tried to recreate this in a trivial program that calls dlopen in a > loop, but haven’t been able to reproduce. > >> Can your offer any suggestions for further debugging this? More > supporting evidence follows. > >> Here is the message when the debugger stops: > >> Process 120004 stopped >> * thread #1, name = ‘xxxxxxxx', stop reason = trace >> frame #0: 0x00002aaaacfca6a0 libc.so.6`__restore_rt >> libc.so.6`__restore_rt: >> -> 0x2aaaacfca6a0 <+0>: movq $0xf, %rax >> 0x2aaaacfca6a7 <+7>: syscall >> 0x2aaaacfca6a9 <+9>: nopl (%rax) > >> libc.so.6`__libc_sigaction: >> 0x2aaaacfca6b0 <+0>: subq $0xd0, %rsp > >> I do not have the stop on shared library events setting enabled: > >> (lldb) settings show target.process.stop-on-sharedlibrary-events >> target.process.stop-on-sharedlibrary-events (boolean) = false > > > >> The backtrace goes back to dlopen: > >> (lldb) bt >> * thread #1, name = ‘xxxxx', stop reason = trace >> * frame #0: 0x00002aaaacfca6a0 libc.so.6`__restore_rt >> frame #1: 0x00002aaaaaab9eb0 ld-linux-x86-64.so.2 >> frame #2: 0x00002aaaaaabdc53 ld-linux-x86-64.so.2`dl_open_worker + 499 >> frame #3: 0x00002aaaaaab9286 ld-linux-x86-64.so.2`_dl_catch_error + > 102 >> frame #4: 0x00002aaaaaabd63a ld-linux-x86-64.so.2`_dl_open + 186 >> frame #5: 0x00002aaaac39df66 libdl.so.2`dlopen_doit + 102 >> frame #6: 0x00002aaaaaab9286 ld-linux-x86-64.so.2`_dl_catch_error + > 102 >> frame #7: 0x00002aaaac39e29c libdl.so.2`_dlerror_run + 124 >> frame #8: 0x00002aaaac39dee1 libdl.so.2`__dlopen_check + 49 > >> the dyld debug log has a lot of this: >> 209 intern-state DynamicLoaderPOSIXDYLD::RendezvousBreakpointHit pid > 153501 stop_when_images_change=false >> 210 intern-state DynamicLoaderPOSIXDYLD::RendezvousBreakpointHit > called for pid 153501 >> 211 intern-state DYLDRendezvous::Resolve address size: 8, padding 4 >> 212 intern-state DYLDRendezvous::Resolve cursor = 0x2aaaaaccc160 >> 213 intern-state DynamicLoaderPOSIXDYLD::RendezvousBreakpointHit pid > 153501 stop_when_images_change=false >> 214 intern-state DynamicLoaderPOSIXDYLD::RendezvousBreakpointHit > called for pid 153501 >> 215 intern-state DYLDRendezvous::Resolve address size: 8, padding 4 >> 216 intern-state DYLDRendezvous::Resolve cursor = 0x2aaaaaccc160 > > > >> thanks, >> --steve > > >> In the woods too, a man casts off his years, as the snake his slough, > and at what period soever of life, is always a child. > > > >> _______________________________________________ >> LLVM Developers mailing list >> llvm-...@lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > _______________________________________________ > lldb-dev mailing list > lldb-dev@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
