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inferior process exits due to SIGTRAP on FreeBSD after detach, or exiting LLDB #19268

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emaste opened this issue Feb 19, 2014 · 7 comments
Closed

inferior process exits due to SIGTRAP on FreeBSD after detach, or exiting LLDB #19268

emaste opened this issue Feb 19, 2014 · 7 comments
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bugzilla Issues migrated from bugzilla lldb

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@emaste
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emaste commented Feb 19, 2014

Bugzilla Link 18894
Resolution FIXED
Resolved on Apr 01, 2014 16:29
Version unspecified
OS FreeBSD

Extended Description

Invoke lldb against some target e.g. /bin/sleep, set a breakpoint, run, then detach when the breakpoint is hit. The inferior dumps core with SIGTRAP.
(LLDB r201577)

Typescript:

joule% bin/lldb /bin/sleep 60
Current executable set to '/bin/sleep' (x86_64).
(lldb) b main
Breakpoint 1: where = sleep`main + 20 at sleep.c:75, address = 0x0000000000400964
(lldb) run
Process 26485 launching
Process 26485 stopped
(lldb) Process 26485 launched: '/bin/sleep' (x86_64)
Process 26485 stopped

  • thread #​1: tid = 100436, 0x0000000000400964 sleepmain(argc=<unavailable>, argv=0x00007fffffffd730) + 20 at sleep.c:75, stop reason = breakpoint 1.1 frame #&#8203;0: 0x0000000000400964 sleepmain(argc=, argv=0x00007fffffffd730) + 20 at sleep.c:75
    72 if (argc != 2)
    73 usage();
    74
    -> 75 if (sscanf(argv[1], "%lf%1s", &d, buf) != 1)
    76 usage();
    77 if (d > INT_MAX)
    78 usage();
    (lldb) detach
    Process 26485 detached
    (lldb) Detaching from process 26485
    (lldb) quit
    joule% ls sleep.core
    sleep.core
    joule% bin/lldb /bin/sleep -c sleep.core
    Core file '/data/emaste/src/llvm/build/sleep.core' (x86_64) was loaded.
    Process 0 stopped
  • thread #​1: tid = 0, 0x0000000000400965 sleepmain(argc=<unavailable>, argv=0x00007fffffffd730) + 21 at sleep.c:75, name = 'sleep', stop reason = signal SIGTRAP frame #&#8203;0: 0x0000000000400965 sleepmain(argc=, argv=0x00007fffffffd730) + 21 at sleep.c:75
    72 if (argc != 2)
    73 usage();
    74
    -> 75 if (sscanf(argv[1], "%lf%1s", &d, buf) != 1)
    76 usage();
    77 if (d > INT_MAX)
    78 usage();
    (lldb)
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emaste commented Feb 19, 2014

assigned to @emaste

@emaste
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emaste commented Feb 20, 2014

the breakpoint is not cleaned up upon detach

(lldb) log enable lldb break
(lldb) log enable freebsd ptrace
(lldb) b main
Target::CreateBreakpoint (internal = no) => break_id = 1: name = 'main'

Added location: 1.1:
module = /bin/ls
compile unit = ls.c
function = main
location = /tank/emaste/src/freebsd-stable-9/bin/ls/ls.c:166
address = 0x0000000000403069
resolved = false
hit count = 0

Breakpoint 1: where = ls`main + 9 at ls.c:166, address = 0x0000000000403069
(lldb) run
ptrace(PT_TRACE_ME, 0, 0x0, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 990
Process 50631 launching
Target::CreateBreakpoint (internal = yes) => break_id = -1: address = 0x0000000000401dc0

Process::EnableSoftwareBreakpoint (site_id = 1) addr = 0x401dc0
ptrace(PT_IO, 50631, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 160
PT_IO: op=READ_D offs=401dc0 size=1
ptrace(PT_IO, 50631, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 176
PT_IO: op=WRITE_D offs=401dc0 size=1
ptrace(PT_IO, 50631, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 160
PT_IO: op=READ_D offs=401dc0 size=1
Process::EnableSoftwareBreakpoint (site_id = 1) addr = 0x401dc0 -- SUCCESS
Process::EnableSoftwareBreakpoint (site_id = 2) addr = 0x403069
ptrace(PT_IO, 50631, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 160
PT_IO: op=READ_D offs=403069 size=1
ptrace(PT_IO, 50631, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 176
PT_IO: op=WRITE_D offs=403069 size=1
ptrace(PT_IO, 50631, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 160
PT_IO: op=READ_D offs=403069 size=1
Process::EnableSoftwareBreakpoint (site_id = 2) addr = 0x403069 -- SUCCESS

...

ptrace(PT_GETREGS, 103027, 0x7fffff9fcdd0, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 309
PT_GETREGS: ip=0x403069
PT_GETREGS: sp=0x7fffffffd510
PT_GETREGS: bp=0x7fffffffd550
PT_GETREGS: ax=0xffffffffffffffff
frame #​0: 0x0000000000403069 ls`main(argc=1, argv=0x00007fffffffd578) + 9 at ls.c:166
163 char bp = tcapbuf;
164 #endif
165
-> 166 (void)setlocale(LC_ALL, "");
167
168 / Terminal defaults to -Cq, non-terminal defaults to -1. */
169 if (isatty(STDOUT_FILENO)) {
(lldb) detach
ptrace(PT_DETACH, 45195, 0x0, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 747
Process 45195 detached
(lldb) (lldb) Detaching from process 45195
(lldb)

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emaste commented Feb 20, 2014

Initial fix in 201724

There is still an issue when quitting LLDB.

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emaste commented Mar 7, 2014

quitting while stopped at a breakpoint looks like this (with log enable freebsd ptrace & lldb process):

(lldb) quit
Quitting LLDB will kill one or more processes. Do you really want to proceed: [Y/n] y
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 166
PT_IO: op=READ_D offs=400480 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 182
PT_IO: op=WRITE_D offs=400480 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 166
PT_IO: op=READ_D offs=400480 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 166
PT_IO: op=READ_D offs=4005b0 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 182
PT_IO: op=WRITE_D offs=4005b0 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 166
PT_IO: op=READ_D offs=4005b0 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 166
PT_IO: op=READ_D offs=800602d20 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 182
PT_IO: op=WRITE_D offs=800602d20 size=1
ptrace(PT_IO, 74686, 0x7fffff9fce08, 0) called from file ../tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp line 166
PT_IO: op=READ_D offs=800602d20 size=1
Process::SetPrivateState (exited)
Process::SetPrivateState (exited) stop_id = 5
Process::ControlPrivateStateThread (signal = 1)
Sending control event of type: 1.
Process::ShouldBroadcastEvent (0x808cdee20) => new state: exited, last broadcast state: exited - YES
Process::HandlePrivateEvent (pid = 74686) broadcasting new state exited (old state stopped) to public
Process::RunPrivateStateThread (arg = 0x808aed500, pid = 74686) about to exit with internal state exited...
Process::RunPrivateStateThread (arg = 0x808aed500, pid = 74686) thread exiting...
The control event killed the private state thread without having to cancel.

Went to stop the private state thread, but it was already invalid.

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emaste commented Mar 10, 2014

It seems ProcessPOSIX::DoDestroy is incomplete; this PoC patch addresses the aborting debugees and the delayed quit:

--- a/source/Plugins/Process/POSIX/ProcessPOSIX.cpp
+++ b/source/Plugins/Process/POSIX/ProcessPOSIX.cpp
@@ -351,6 +351,8 @@ ProcessPOSIX::DoDestroy()
return error;
}

  •    error = m_monitor->Detach(GetID());                                    

  •    SetPrivateState(eStateExited);
    }

After this there are two new failures, related to "process kill":

test_state_after_continue_with_dwarf (TestThreadStates.ThreadStateTestCase)
test_state_after_expression_with_dwarf (TestThreadStates.ThreadStateTestCase)

Need to determine exactly what is appropriate for DoDestroy.

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emaste commented Mar 24, 2014

Change committed to FreeBSD in http://svnweb.freebsd.org/changeset/base/263678

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emaste commented Apr 1, 2014

Committed in r205315 and r205337

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 9, 2021
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