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[Bug gdb/14018] New: Win32 fails to continue with "winerr 5" (pcregister not available) after SigTrap while process paused
- From: "gdb.bugs at mfriebe dot de" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: Tue, 24 Apr 2012 22:45:20 +0000
- Subject: [Bug gdb/14018] New: Win32 fails to continue with "winerr 5" (pcregister not available) after SigTrap while process paused
- Auto-submitted: auto-generated
http://sourceware.org/bugzilla/show_bug.cgi?id=14018
Bug #: 14018
Summary: Win32 fails to continue with "winerr 5" (pc register
not available) after SigTrap while process paused
Product: gdb
Version: 7.4
Status: NEW
Severity: normal
Priority: P2
Component: gdb
AssignedTo: unassigned@sourceware.org
ReportedBy: gdb.bugs@mfriebe.de
Classification: Unclassified
Created attachment 6366
--> http://sourceware.org/bugzilla/attachment.cgi?id=6366
pascal (src and bin) for reproducing
This bug appears to be a regression. It is present it 7.3 and 7.4. But was not
in previous 7.x)
On Windows in order to pause a running process for debugging, it is custom to
call
CreateRemoteThread(handle_to_debugged_process, 0,0, GetProcAddress(hMod,
'DebugBreak') ...)
This leads to GDB reporting:
*stopped,reason="signal-received",signal-name="SIGTRAP",signal-meaning="Trace/breakpoint
trap",frame=
However if the above happens, while the app is already paused (e.g. after
reaching a breakpoint) then the app can not be continued.
This can not always be avoided. It may happen as a race condition, where the
breakpoint is hit, just before the signal could be sent.
The first continue will correctly lead to another pause/interrupt reporting the
SigTrap.
Trying to continue from this will report
-exec-continue
&"warning: SuspendThread failed. (winerr 5)\n"
^error,msg="PC register is not available"
-exec-continue
&"warning: SuspendThread failed. (winerr 5)\n"
^error,msg="PC register is not available"
**** To reproduce (using Free Pascal) Win 32 / Vista (probably any other too)
intel
I have included a helper app (in pascal) to trigger the SigTrap (source and
bin).
Compile with: fpc.exe dbgbrk.pas
The app to be debugged is test.exe
compile: fpc.exe -g test.pas
Run gdb:
gdb -i mi test.exe
-break-insert test.pas:4
-exec-run
~"Starting program: B:\\dbg\\test.exe \n"
=thread-group-started,id="i1",pid="8372"
=thread-created,id="1",group-id="i1"
~"[New Thread 8372.0x26c4]\n"
....
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame={addr="0x004013f9",func="FOO"
Take the PID reported by gdb (in the example 8372) and run (while the app is
paused at the break point)
dbgbrk.exe 8372
-exec-continue
^running
....
*stopped,reason="signal-received",signal-name="SIGTRAP",signal-meaning="Trace/breakpoint
trap",
-exec-continue
^running
....
&"warning: SuspendThread failed. (winerr 5)\n"
^error,msg="PC register is not available"
-exec-continue
&"warning: SuspendThread failed. (winerr 5)\n"
^error,msg="PC register is not available"
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