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The recent commit 421490af33bf ("gdbserver/linux: Access memory even
if threads are running") caused a regression in
gdb.threads/access-mem-running-thread-exit.exp with gdbserver, which I
somehow missed. Like so:
(gdb) print global_var
Cannot access memory at address 0x555555558010
(gdb) FAIL: gdb.threads/access-mem-running-thread-exit.exp: non-stop: access mem (print global_var after writing, inf=2, iter=1)
The problem starts with GDB telling GDBserver to select a thread, via
the Hg packet, which GDBserver complies with, then that thread exits,
and GDB, without knowing the thread is gone, tries to write to memory,
through the context of the previously selected Hg thread.
GDBserver's GDB-facing memory access routines, gdb_read_memory and
gdb_write_memory, call set_desired_thread to make GDBserver re-select
the thread that GDB has selected with the Hg packet. Since the thread
is gone, set_desired_thread returns false, and the memory access
fails.
Now, to access memory, it doesn't really matter which thread is
selected. All we should need is the target process. Even if the
thread that GDB previously selected is gone, and GDB does not yet know
about that exit, it shouldn't matter, GDBserver should still know
which process that thread belonged to.
Fix this by making GDBserver track the current process separately,
like GDB also does. Add a new set_desired_process routine that is
similar to set_desired_thread, but just sets the current process,
leaving the current thread as NULL. Use it in the GDB-facing memory
read and write routines, to avoid failing if the selected thread is
gone, but the process is still around.
Change-Id: I4ff97cb6f42558efbed224b30d5c71f6112d44cd
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This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
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Introduce a class for restoring the current thread and a function to
switch to the given thread. This is a preparation for a refactoring
that aims to remove direct assignments to 'current_thread'.
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I stumbled on a bug caused by the fact that a code path read
target_waitstatus::value::sig (expecting it to contain a gdb_signal
value) while target_waitstatus::kind was TARGET_WAITKIND_FORKED. This
meant that the active union field was in fact
target_waitstatus::value::related_pid, and contained a ptid. The read
signal value was therefore garbage, and that caused GDB to crash soon
after. Or, since that GDB was built with ubsan, this nice error
message:
/home/simark/src/binutils-gdb/gdb/linux-nat.c:1271:12: runtime error: load of value 2686365, which is not a valid value for type 'gdb_signal'
Despite being a large-ish change, I think it would be nice to make
target_waitstatus safe against that kind of bug. As already done
elsewhere (e.g. dynamic_prop), validate that the type of value read from
the union matches what is supposed to be the active field.
- Make the kind and value of target_waitstatus private.
- Make the kind initialized to TARGET_WAITKIND_IGNORE on
target_waitstatus construction. This is what most users appear to do
explicitly.
- Add setters, one for each kind. Each setter takes as a parameter the
data associated to that kind, if any. This makes it impossible to
forget to attach the associated data.
- Add getters, one for each associated data type. Each getter
validates that the data type fetched by the user matches the wait
status kind.
- Change "integer" to "exit_status", "related_pid" to "child_ptid",
just because that's more precise terminology.
- Fix all users.
That last point is semi-mechanical. There are a lot of obvious changes,
but some less obvious ones. For example, it's not possible to set the
kind at some point and the associated data later, as some users did.
But in any case, the intent of the code should not change in this patch.
This was tested on x86-64 Linux (unix, native-gdbserver and
native-extended-gdbserver boards). It was built-tested on x86-64
FreeBSD, NetBSD, MinGW and macOS. The rest of the changes to native
files was done as a best effort. If I forgot any place to update in
these files, it should be easy to fix (unless the change happens to
reveal an actual bug).
Change-Id: I0ae967df1ff6e28de78abbe3ac9b4b2ff4ad03b7
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Add a constructor and a destructor. The constructor takes care of the
initialization that happened in add_thread, while the destructor takes
care of the freeing that happened in free_one_thread. This is needed to
make target_waitstatus non-POD, as thread_info contains a member of that
type.
Change-Id: I1db321b4de9dd233ede0d5c101950f1d6f1d13b7
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This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
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This patch moves gdbserver to the top level.
This patch is as close to a pure move as possible -- gdbserver still
builds its own variant of gnulib and gdbsupport. Changing this will
be done in a separate patch.
[v2] Note that, per Simon's review comment, this patch changes the
tree so that gdbserver is not built for or1k or score. This makes
sense, because there is apparently not actually a gdbserver port here.
[v3] This version of the patch also splits out some configury into a
new file, gdbserver/configure.host, so that the top-level configure
script can simply rely on it in order to decide whether gdbserver
should be built.
[v4] This version adds documentation and removes some unnecessary
top-level dependencies.
[v5] Update docs to mention "make all-gdbserver" and change how
top-level configure decides whether to build gdbserver, switching to a
single, shared script.
Tested by the buildbot.
ChangeLog
2020-02-07 Tom Tromey <tom@tromey.com>
Pedro Alves <palves@redhat.com>
* src-release.sh (GDB_SUPPORT_DIRS): Add gdbserver.
* gdbserver: New directory, moved from gdb/gdbserver.
* configure.ac (host_tools): Add gdbserver.
Only build gdbserver on certain systems.
* Makefile.in, configure: Rebuild.
* Makefile.def (host_modules, dependencies): Add gdbserver.
* MAINTAINERS: Add gdbserver.
gdb/ChangeLog
2020-02-07 Tom Tromey <tom@tromey.com>
* README: Update gdbserver documentation.
* gdbserver: Move to top level.
* configure.tgt (build_gdbserver): Remove.
* configure.ac: Remove --enable-gdbserver.
* configure: Rebuild.
* Makefile.in (distclean): Don't mention gdbserver.
Change-Id: I826b7565b54604711dc7a11edea0499cd51ff39e
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