Re: lldb unusable for regular user

Hi Volodya,

It works for me:
[mizhka_at_gidrarium ~/temp/20170919]$ cc -O0 -g test.c -o test
[mizhka_at_gidrarium ~/temp/20170919]$ ./test
PID: 12293
(failed reverse-i-search)`': ^C
[mizhka_at_gidrarium ~/temp/20170919]$ ./test
PID: 12294
load: 0.68  cmd: test 12294 [nanslp] 1.39r 0.00u 0.00s 0% 2316k
load: 0.68  cmd: test 12294 [nanslp] 3.57r 0.00u 0.00s 0% 2316k
load: 0.68  cmd: test 12294 [nanslp] 3.88r 0.00u 0.00s 0% 2316k
load: 0.68  cmd: test 12294 [nanslp] 4.18r 0.00u 0.00s 0% 2316k
load: 0.71  cmd: test 12294 [nanslp] 8.57r 0.00u 0.00s 0% 2316k
load: 0.71  cmd: test 12294 [nanslp] 9.33r 0.00u 0.00s 0% 2316k
load: 0.71  cmd: test 12294 [nanslp] 9.83r 0.00u 0.00s 0% 2316k
[mizhka_at_gidrarium ~/temp/20170919]$ lldb ./test
(lldb) target create "./test"
Current executable set to './test' (x86_64).
(lldb) run
Process 12300 launching
Process 12300 launched: './test' (x86_64)
PID: 12300
Process 12300 exited with status = 0 (0x00000000)
(lldb) exit
[mizhka_at_gidrarium ~/temp/20170919]$ uname -a
FreeBSD gidrarium 12.0-CURRENT FreeBSD 12.0-CURRENT #2 r321414: Mon Jul 24
21:41:54 MSK 2017     mizhka_at_gidrarium:/usr/obj/usr/src/sys/GENERIC  amd64
[mizhka_at_gidrarium ~/temp/20170919]$ type lldb
lldb is hashed (/usr/bin/lldb)
[mizhka_at_gidrarium ~/temp/20170919]$ /usr/bin/lldb -v
lldb version 5.0.0
  clang revision 308421

But I have r321414 with small patch: https://reviews.freebsd.org/D11738

Today/tomorrow I'll update to latest revision.

Hope this information will be useful for you to identify root cause.

Thanks!


On Mon, Sep 18, 2017 at 2:41 PM, Vladimir Zakharov <zakharov.vv_at_gmail.com>
wrote:

> Hello!
>
> lldb coredumps for regular user, but works for root.
>
> > uname -a
> FreeBSD vzakharov 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r323675: Sun Sep 17
> 21:14:33 MSK 2017     root_at_vzakharov:/home/obj/usr/src/sys/GENERIC-NODEBUG
> amd64
> > cat test.c
> #include <stdio.h>
> #include <unistd.h>
>
> int main()
> {
>   printf("PID: %d\n", getpid());
>   sleep(10);
>   return 0;
> }
> > cc -O0 -g test.c -o test
> > lldb ./test
> (lldb) target create "./test"
> Current executable set to './test' (x86_64).
> (lldb) run
> Process 37758 launching
> Process 37758 launched: './test' (x86_64)
> Segmentation fault (core dumped)
> Exit 139
> > sudo lldb ./test
> (lldb) target create "./test"
> Current executable set to './test' (x86_64).
> (lldb) run
> Process 37776 launching
> Process 37776 launched: './test' (x86_64)
> PID: 37776
> Process 37776 exited with status = 0 (0x00000000)
> (lldb)
>
>
> Postmortem by gdb:
> > gdb ./test test.core
> ...
> [New LWP 101456]
> Core was generated by `./test'.
> Program terminated with signal SIGTRAP, Trace/breakpoint trap.
> #0  _start (ap=0x7fffffffe858, cleanup=0x800605910 <rtld_exit>) at
> /usr/src/lib/csu/amd64/crt1.c:50
> 50      {
> (gdb) bt
> #0  _start (ap=0x7fffffffe858, cleanup=0x800605910 <rtld_exit>) at
> /usr/src/lib/csu/amd64/crt1.c:50
> (gdb) f
> #0  _start (ap=0x7fffffffe858, cleanup=0x800605910 <rtld_exit>) at
> /usr/src/lib/csu/amd64/crt1.c:50
> 50      {
>
> > gdb `which lldb` lldb.core
> ...
> Reading symbols from /usr/bin/lldb...Reading symbols from
> /usr/lib/debug//usr/bin/lldb.debug...done.
> done.
> [New LWP 101610]
> [New LWP 100968]
> [New LWP 100126]
> [New LWP 101631]
> [New LWP 101637]
> [New LWP 101662]
> [New LWP 101672]
> [New LWP 100337]
> [New LWP 101593]
> Core was generated by `lldb ./test'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20,
> context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
> 60      ./md-unwind-support.h: No such file or directory.
> [Current thread is 1 (LWP 101610)]
> (gdb) f
> #0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20,
> context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
> 60      in ./md-unwind-support.h
> (gdb) bt
> #0  x86_64_freebsd_fallback_frame_state (context=0x7fffddff6e20,
> context=0x7fffddff6e20, fs=0x7fffddff6b70) at ./md-unwind-support.h:60
> #1  uw_frame_state_for (context=context_at_entry=0x7fffddff6e20, fs=fs_at_entry=0x7fffddff6b70)
> at /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind-dw2.c:1249
> #2  0x0000000804f6cffb in _Unwind_ForcedUnwind_Phase2 (exc=exc_at_entry=0x806b23230,
> context=context_at_entry=0x7fffddff6e20) at /wrkdirs/usr/ports/lang/gcc6/
> work/gcc-6.4.0/libgcc/unwind.inc:155
> #3  0x0000000804f6d334 in _Unwind_ForcedUnwind (exc=0x806b23230,
> stop=0x804631760 <thread_unwind_stop>, stop_argument=<optimized out>) at
> /wrkdirs/usr/ports/lang/gcc6/work/gcc-6.4.0/libgcc/unwind.inc:207
> #4  0x00000008046315c3 in _Unwind_ForcedUnwind (ex=<optimized out>,
> stop_func=0xe, stop_arg=0x806b23000) at /usr/src/lib/libthr/thread/
> thr_exit.c:106
> #5  thread_unwind () at /usr/src/lib/libthr/thread/thr_exit.c:172
> #6  _pthread_exit_mask (status=<optimized out>, mask=<optimized out>) at
> /usr/src/lib/libthr/thread/thr_exit.c:254
> #7  0x00000008046313eb in _pthread_exit (status=0x806b23000) at
> /usr/src/lib/libthr/thread/thr_exit.c:206
> #8  0x0000000804623c0d in thread_start (curthread=0x806b23000) at
> /usr/src/lib/libthr/thread/thr_create.c:289
> #9  0x00007fffdddf7000 in ?? ()
> Backtrace stopped: Cannot access memory at address 0x7fffddff7000
>
> --
> Regards,                 | "In theory there is no difference between theory
>   Vladimir Zakharov      | and practice. In practice there is."- Yogi Berra
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