On ppc-lynx178, resuming the execution of a program after hitting
a breakpoint sometimes triggers a spurious SIG61 event:
(gdb) cont
Continuing.
Program received signal SIG61, Real-time event 61.
[Switching to Thread 39]
0x10002324 in a_test.task1 (<_task>=0x3ffff774) at a_test.adb:30
30 select -- Task 1
From this point on, continuing again lets the signal kill the program.
Using "signal 0" or configuring GDB to discard the signal does not
help either, as the program immediately reports the same signal again.
What happens is the following:
- GDB sends a single-step order to gdbserver: $vCont;s:31
This tells GDBserver to do a step using thread 0x31=49.
GDBserver does the step, and thread 49 receives the SIGTRAP
indicating that the step has finished.
- GDB then sends a "continue", but this time does not specify
which thread to continue: $vCont;c
GDBserver uses an arbitrary thread's ptid to resume the program's
execution (the current_inferior's ptid was chosen for that).
See lynx-low.c:lynx_resume:
if (ptid_equal (ptid, minus_one_ptid))
ptid = thread_to_gdb_id (current_inferior);
So far on all LynxOS platforms, this has been good enough. But
not so on LynxOS 178. If the ptid used to resume the execution
is not the same as the thread that did the step, we get the weird
signal.
This patch fixes the problem by saving the ptid of the thread
that last caused an event, received during a call to waitpid.
The ptid is saved in per-process private data.
gdb/gdbserver/ChangeLog:
* lynx-low.c (struct process_info_private): New type.
(lynx_add_process): New function.
(lynx_create_inferior, lynx_attach): Replace calls to
add_process by calls to lynx_add_process.
(lynx_resume): If PTID is null, then try using
current_process()->private->last_wait_event_ptid.
Add comments.
(lynx_clear_inferiors): Delete. The contents of that function
has been inlined in lynx_mourn;
(lynx_wait_1): Save the ptid in the process's private data.
(lynx_mourn): Free the process' private data. Replace call
to lynx_clear_inferiors by call to clear_inferiors.
... following Pedro's advice of using a temporary macro.
gdb/gdbserver/ChangeLog:
* lynx-low.c (ptrace_request_to_str): Define a temporary
macro and use it to simplify this function's implementation.
Before this patch, the ptid passed to lynx_resume was completely
ignored, and we used the current_inferior. This resulted in trying
to resume the inferior execution using the wrong ptid after having
received a thread create/exit event, because the inferior_ptid
was still set to the ptid prior to receiving the signal.
gdb/gdbserver/ChangeLog:
* lynx-low.c (lynx_resume): Use the resume_info parameter
to determine the ptid for the lynx_ptrace call, unless
it is equal to minus_one_ptid, in which case we use the
ptid of the current_inferior.
(lynx_wait_1): After having received a thread create/exit
event, resume the inferior's execution using the signaling
thread's ptid, rather than the old ptid.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
We use this ptrace request when handling SIGTRAP signals,
and without this change, the debug trances show:
PTRACE (<unknown-request>, ...
This patch fixes this.
gdb/gdbserver/ChangeLog:
* lynx-low.c (ptrace_request_to_str): Add handling for
PTRACE_GETTRACESIG.
LynxOS 178 does not define this macro.
gdb/gdbserver/ChangeLog:
* lynx-low.c (ptrace_request_to_str): Do not handle
PTRACE_GETTHREADLIST if this macro does not exist.
ARI fixes: move gdb_wait and gdb_stat headers to common subdirectory.
* gdb_stat.h: Delete. Moved to common directory.
* common/gdb_stat.h: New file.
* gdb_wait.h: Delete. Moved to common directory.
* common/gdb_wait.h: New file.
* Makefile.in (H_FILES_NO_SRC): Adapt to new header
location.
* contrib/ari/gdb_ari.sh (wait.h rule): Adapt to new gdb_wait.h
location.
(stat.h rule): Adapt to new gdb_stat.h location.
* common/linux-osdata.c: Include "gdb_stat.h" header instead of
<sys/stat.h> header.
* common/linux-ptrace.c: Include "gdb_wait.h" header instead of
<sys/wait.h> header.
gdbserver ChangeLog entry:
2012-11-15 Pierre Muller <muller@sourceware.org>
* configure.ac (AC_CHECK_HEADERS): Add wait.h header.
* config.in: Regenerate.
* configure: Regenerate.
* linux-low.c: Use "gdb_stat.h" header instead of <sys/stat.h> header.
Use "gdb_wait.h" header instead of <sys/wait.h> header.
* lynx-low.c: Use "gdb_wait.h" header instead of <sys/wait.h> header.
* remote-utils.c: Use "gdb_stat.h" header instead of <sys/stat.h>
header.
* server.c: Remove HAVE_WAIT_H conditional. Use "gdb_wait.h" header
instead of <sys/wait.h> header.
* spu-low.c: Use "gdb_wait.h" header instead of <sys/wait.h> header.
Some of the PTRACE_ macros/values were removed in LynxOS 5.x.
Since we have not use them so far, the chances that we will use them
one day are very small. So I decided to delete them.
gdb/gdbserver/ChangeLog:
* lynx-low.c (ptrace_request_to_str): Remove handling for
request values that have been removed in LynxOS 5.x.
This is one of the changes needed in order to build gdbserver on
LynxOS 5.x.
Really interesting: On LynxOS 4.x, there is a #warning when sys/ptrace.h
is used (explaining that ptrace.h will be used instead), whereas this
file was removed from LynxOS 5.x. The contents of sys/ptrace.h on 4.x
(or at least the meat of it):
#if defined(__GNUC__) || defined(__GNUG__)
#if !defined(__NO_INCLUDE_WARN__)
#warning Using <ptrace.h> instead of <sys/ptrace.h>
#endif /* defined(__NO_INCLUDE_WARN__) */
#endif /* defined(__GNUC__) || defined(__GNUG__) */
#include <ptrace.h>
The fix I went for, for now, is to just include <sys/ptrace.h>
unconditionally. I could have done some configury, but we already
have to build with -D__NO_INCLUDE_WARN__ to avoid the warnings
anyway, and that's unvoidable, due to system includes themselves
including the "wrong" header file.
Since <sys/ptrace.h> seems to be the choice that was made for LynxOS,
and since it works to include it on LynxOS 4.x, I think that's the simplest
solution.
gdb/gdbserver/ChangeLog:
* lynx-low.c, lynx-ppc-low.c: Include <sys/ptrace.h> instead of
<ptrace.h>
This patch adds support for powerpc-lynxos.
gdbserver/ChangeLog:
* gdbserver/lynx-low.c, gdbserver/lynx-low.h,
gdbserver/lynx-ppc-low.c: New files.
* Makefile.in (lynx_low_h): New variable.
(lynx-low.o, lynx-ppc-low.o): New rules.
* configure.ac: On LynxOS, link with -lnetinet.
* configure.srv: Add handling of powerpc-*-lynxos* targets.
* configure: regenerate.
