forked from Imagelibrary/binutils-gdb
4bc72a4571
I think there is a problem with the disable_breakpoints_in_shlibs
function: it can disable breakpoint locations without calling
notify_breakpoint_modified. This means that the Python API's
breakpoint_modified event will not trigger, nor will the MI send a
breakpoint modified event.
I started looking at disable_breakpoints_in_shlibs because of an
earlier commit:
commit 8c48ec7a61
Date: Thu Aug 29 12:34:15 2024 +0100
gdb: handle dprintf breakpoints when unloading a shared library
Currently disable_breakpoints_in_shlibs is only called from one
location, clear_solib in solib.c. clear_solib also calls
notify_solib_unloaded for every solib in the program_space of
interest, and notify_solib_unloaded will call
disable_breakpoints_in_unloaded_shlib via the solib_unloaded
observer. These two function, disable_breakpoints_in_shlibs and
disable_breakpoints_in_unloaded_shlib are very similar in what they
do.
I think that we can remove the disable_breakpoints_in_shlibs call, and
instead, tweak how we call disable_breakpoints_in_unloaded_shlib in
order to get the same end result, except that, after this change, we
will call notify_breakpoint_modified, which means the Python API event
will trigger, and the MI events will be emitted.
All that disable_breakpoints_in_shlibs does is disable some
breakpoints.
Meanwhile, disable_breakpoints_in_unloaded_shlib, will disable the
same set of breakpoints, call notify_breakpoint_modified, and
then (for some breakpoint types) print a message telling the user that
the breakpoint has been disabled. However, this function will ignore
any breakpoints that are already disabled.
As disable_breakpoints_in_shlibs disables the same set of breakpoints,
the result of the current code is that disable_breakpoints_in_shlibs
serves only to prevent the notify_breakpoint_modified call, which I
think is wrong, and to prevent the user message being printed, which I
think is reasonable.
If we remove the disable_breakpoints_in_shlibs call without making any
additional changes, then we start to see some message printed in cases
like this:
(gdb) start
The program being debugged has been started already.
Start it from the beginning? (y or n) y
warning: Temporarily disabling breakpoints for unloaded shared library "/tmp/shared-lib-test/libfoo.so"
Temporary breakpoint 3 at 0x40113e: file test.c, line 9.
Starting program: /tmp/shared-lib-test/test.x
Notice the 'warning:' line, which is new. I think this is confusing
because, in most cases the breakpoint will be enabled again by the
time the inferior reaches `main` and stops.
In the future I'm interested in exploring if GDB could be smarter
about when to print these 'Temporarily disabling breakpoints ...'
messages so that if the 'start' command does mean a breakpoint is left
disabled, then the user would be informed. However, I don't propose
doing that work immediately, and certainly not in this commit. For
now, my intention is to leave things as they are right now, GDB
doesn't warn about disabling breakpoints during an inferior re-start.
To achieve this I think we need to pass a new argument to
disable_breakpoints_in_unloaded_shlib which controls whether we should
print a message about the breakpoint being disabled or not. With this
added we can now silence the warning when the inferior is
restarted (i.e. when disable_breakpoints_in_unloaded_shlib is called
from clear_solib), but keep the warning for cases like stepping over a
dlclose() call in the inferior.
After this commit, GDB now emits breakpoint modified events (in Python
and/or MI) when a breakpoint is disabled as a result of all shared
libraries being unloaded. This will be visible in two places that I
can thing of, the 'nosharedlibrary' command, and when an inferior is
restarted.
268 lines
10 KiB
C++
268 lines
10 KiB
C++
/* Observers
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Copyright (C) 2016-2024 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef GDB_OBSERVABLE_H
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#define GDB_OBSERVABLE_H
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#include "gdbsupport/observable.h"
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#include "target/waitstatus.h"
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struct bpstat;
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struct solib;
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struct objfile;
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struct thread_info;
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struct inferior;
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struct process_stratum_target;
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struct target_ops;
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struct trace_state_variable;
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struct program_space;
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namespace gdb
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{
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namespace observers
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{
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/* The inferior has stopped for real. The BS argument describes the
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breakpoints were are stopped at, if any. Second argument
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PRINT_FRAME non-zero means display the location where the
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inferior has stopped.
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gdb notifies all normal_stop observers when the inferior execution
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has just stopped, the associated messages and annotations have been
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printed, and the control is about to be returned to the user.
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Note that the normal_stop notification is not emitted when the
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execution stops due to a breakpoint, and this breakpoint has a
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condition that is not met. If the breakpoint has any associated
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commands list, the commands are executed after the notification is
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emitted. */
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extern observable<struct bpstat */* bs */, int /* print_frame */> normal_stop;
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/* The inferior was stopped by a signal. */
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extern observable<enum gdb_signal /* siggnal */> signal_received;
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/* The target's register contents have changed. */
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extern observable<struct target_ops */* target */> target_changed;
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/* The executable being debugged by GDB in PSPACE has changed: The user
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decided to debug a different program, or the program he was debugging
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has been modified since being loaded by the debugger (by being
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recompiled, for instance). The path to the new executable can be found
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by examining PSPACE->exec_filename.
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When RELOAD is true the path to the executable hasn't changed, but the
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file does appear to have changed, so GDB reloaded it, e.g. if the user
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recompiled the executable. when RELOAD is false then the path to the
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executable has not changed. */
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extern observable<struct program_space */* pspace */,
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bool /*reload */> executable_changed;
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/* gdb has just connected to an inferior. For 'run', gdb calls this
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observer while the inferior is still stopped at the entry-point
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instruction. For 'attach' and 'core', gdb calls this observer
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immediately after connecting to the inferior, and before any
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information on the inferior has been printed. */
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extern observable<inferior */* inferior */> inferior_created;
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/* The inferior EXEC_INF has exec'ed a new executable file.
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Execution continues in FOLLOW_INF, which may or may not be the same as
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EXEC_INF, depending on "set follow-exec-mode". */
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extern observable<inferior */* exec_inf */, inferior */* follow_inf */>
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inferior_execd;
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/* The inferior PARENT_INF has forked. If we are setting up an inferior for
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the child (because we follow only the child or we follow both), CHILD_INF
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is the child inferior. Otherwise, CHILD_INF is nullptr.
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FORK_KIND is TARGET_WAITKIND_FORKED or TARGET_WAITKIND_VFORKED. */
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extern observable<inferior */* parent_inf */, inferior */* child_inf */,
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target_waitkind /* fork_kind */> inferior_forked;
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/* The shared library specified by SOLIB has been loaded. Note that
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when gdb calls this observer, the library's symbols probably
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haven't been loaded yet. */
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extern observable<solib &/* solib */> solib_loaded;
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/* The shared library SOLIB has been unloaded from program space PSPACE.
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The SILENT argument indicates that GDB doesn't wish to notify the CLI
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about any non-error consequences of unloading the solib, e.g. when
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breakpoints are disabled.
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Note when gdb calls this observer, the library's symbols have not
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been unloaded yet, and thus are still available. */
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extern observable<program_space *, const solib &/* solib */,
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bool /* still_in_use */, bool /* silent */> solib_unloaded;
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/* The symbol file specified by OBJFILE has been loaded. */
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extern observable<struct objfile */* objfile */> new_objfile;
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/* All objfiles from PSPACE were removed. */
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extern observable<program_space */* pspace */> all_objfiles_removed;
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/* The object file specified by OBJFILE is about to be freed. */
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extern observable<struct objfile */* objfile */> free_objfile;
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/* The thread specified by T has been created. */
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extern observable<struct thread_info */* t */> new_thread;
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/* The thread specified by T has exited. EXIT_CODE is the thread's
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exit code, if available. The SILENT argument indicates that GDB is
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removing the thread from its tables without wanting to notify the
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CLI about it. */
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extern observable<thread_info */* t */,
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std::optional<ULONGEST> /* exit_code */,
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bool /* silent */> thread_exit;
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/* The thread specified by T has been deleted, with delete_thread.
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This is called just before the thread_info object is destroyed with
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operator delete. */
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extern observable<thread_info */* t */> thread_deleted;
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/* An explicit stop request was issued to PTID. If PTID equals
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minus_one_ptid, the request applied to all threads. If
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ptid_is_pid(PTID) returns true, the request applied to all
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threads of the process pointed at by PTID. Otherwise, the
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request applied to the single thread pointed at by PTID. */
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extern observable<ptid_t /* ptid */> thread_stop_requested;
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/* The target was resumed. The PTID parameter specifies which
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thread was resume, and may be RESUME_ALL if all threads are
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resumed. */
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extern observable<ptid_t /* ptid */> target_resumed;
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/* The target is about to be proceeded. */
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extern observable<> about_to_proceed;
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/* A new breakpoint B has been created. */
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extern observable<struct breakpoint */* b */> breakpoint_created;
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/* A breakpoint has been destroyed. The argument B is the
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pointer to the destroyed breakpoint. */
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extern observable<struct breakpoint */* b */> breakpoint_deleted;
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/* A breakpoint has been modified in some way. The argument B
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is the modified breakpoint. */
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extern observable<struct breakpoint */* b */> breakpoint_modified;
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/* GDB has instantiated a new architecture, NEWARCH is a pointer to the new
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architecture. */
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extern observable<struct gdbarch */* newarch */> new_architecture;
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/* The thread's ptid has changed. The OLD_PTID parameter specifies
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the old value, and NEW_PTID specifies the new value. */
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extern observable<process_stratum_target * /* target */,
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ptid_t /* old_ptid */, ptid_t /* new_ptid */>
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thread_ptid_changed;
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/* The inferior INF has been added to the list of inferiors. At
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this point, it might not be associated with any process. */
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extern observable<struct inferior */* inf */> inferior_added;
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/* The inferior identified by INF has been attached to a
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process. */
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extern observable<struct inferior */* inf */> inferior_appeared;
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/* Inferior INF is about to be detached. */
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extern observable<struct inferior */* inf */> inferior_pre_detach;
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/* Either the inferior associated with INF has been detached from
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the process, or the process has exited. */
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extern observable<struct inferior */* inf */> inferior_exit;
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/* The inferior INF has been removed from the list of inferiors.
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This method is called immediately before freeing INF. */
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extern observable<struct inferior */* inf */> inferior_removed;
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/* The inferior CLONE has been created by cloning INF. */
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extern observable<struct inferior */* inf */, struct inferior */* clone */>
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inferior_cloned;
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/* Bytes from DATA to DATA + LEN have been written to the inferior
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at ADDR. */
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extern observable<struct inferior */* inferior */, CORE_ADDR /* addr */,
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ssize_t /* len */, const bfd_byte */* data */>
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memory_changed;
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/* Called before a top-level prompt is displayed. CURRENT_PROMPT is
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the current top-level prompt. */
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extern observable<const char */* current_prompt */> before_prompt;
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/* Variable gdb_datadir has been set. The value may not necessarily
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change. */
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extern observable<> gdb_datadir_changed;
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/* An inferior function at ADDRESS is about to be called in thread
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THREAD. */
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extern observable<ptid_t /* thread */, CORE_ADDR /* address */>
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inferior_call_pre;
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/* The inferior function at ADDRESS has just been called. This
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observer is called even if the inferior exits during the call.
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THREAD is the thread in which the function was called, which may
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be different from the current thread. */
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extern observable<ptid_t /* thread */, CORE_ADDR /* address */>
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inferior_call_post;
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/* A register in the inferior has been modified by the gdb user. */
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extern observable<const frame_info_ptr &/* frame */, int /* regnum */>
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register_changed;
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/* The user-selected inferior, thread and/or frame has changed. The
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user_select_what flag specifies if the inferior, thread and/or
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frame has changed. */
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extern observable<user_selected_what /* selection */>
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user_selected_context_changed;
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/* This is notified when a styling setting has changed, content may need
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to be updated based on the new settings. */
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extern observable<> styling_changed;
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/* The CLI's notion of the current source has changed. This differs
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from user_selected_context_changed in that it is also set by the
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"list" command. */
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extern observable<> current_source_symtab_and_line_changed;
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/* Called when GDB is about to exit. */
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extern observable<int> gdb_exiting;
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/* When a connection is removed. */
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extern observable<process_stratum_target */* target */> connection_removed;
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/* About to enter target_wait (). */
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extern observable <ptid_t /* ptid */> target_pre_wait;
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/* About to leave target_wait (). */
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extern observable <ptid_t /* event_ptid */> target_post_wait;
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/* New program space PSPACE was created. */
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extern observable <program_space */* pspace */> new_program_space;
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/* The program space PSPACE is about to be deleted. */
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extern observable <program_space */* pspace */> free_program_space;
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extern observable<bool /* enabled */> tui_enabled;
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} /* namespace observers */
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} /* namespace gdb */
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#endif /* GDB_OBSERVABLE_H */
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