From: Kevin Buettner <kevinb@redhat.com>
To: gdb-patches@sourceware.org
Cc: pedro@palves.net, Kevin Buettner <kevinb@redhat.com>,
Tom de Vries <tdevries@suse.de>
Subject: [PATCH v5 8/8] Forced quit cases handled by resetting sync_quit_force_run
Date: Wed, 22 Feb 2023 16:46:13 -0700 [thread overview]
Message-ID: <20230222234613.29662-9-kevinb@redhat.com> (raw)
In-Reply-To: <20230222234613.29662-1-kevinb@redhat.com>
During my audit of the use of gdb_exception with regard to QUIT
processing, I found a try/catch in the scoped_switch_fork_info
destructor.
Static analysis found this call path from the destructor to
maybe_quit():
scoped_switch_fork_info::~scoped_switch_fork_info()
-> remove_breakpoints()
-> remove_breakpoint(bp_location*)
-> remove_breakpoint_1(bp_location*, remove_bp_reason)
-> memory_validate_breakpoint(gdbarch*, bp_target_info*)
-> target_read_memory(unsigned long, unsigned char*, long)
-> target_read(target_ops*, target_object, char const*, unsigned char*, unsigned long, long)
-> maybe_quit()
Since it's not safe to do a 'throw' from a destructor, we simply
call set_quit_flag and, for gdb_exception_forced_quit, also
set sync_quit_force_run. This will cause the appropriate
exception to be rethrown at the next QUIT check.
Another case is the try / catch in tui_getc() in tui-io.c. The
existing catch swallows the exception. I've added a catch for
'gdb_exception_forced_quit', which also swallows the exception,
but also sets sync_quit_force_run and calls set_quit_flag in
order to restart forced quit processing at the next QUIT check.
This is required because it isn't safe to throw into/through
readline.
Thanks to Pedro Alves for suggesting this idea.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=26761
Tested-by: Tom de Vries <tdevries@suse.de>
---
gdb/linux-fork.c | 12 ++++++++++++
gdb/tui/tui-io.c | 8 ++++++++
gdb/tui/tui.c | 7 +++++++
3 files changed, 27 insertions(+)
diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index 61545b859ea..a6e74c0cb52 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -430,6 +430,18 @@ class scoped_switch_fork_info
fork_load_infrun_state (m_oldfp);
insert_breakpoints ();
}
+ catch (const gdb_exception_quit &ex)
+ {
+ /* We can't throw from a destructor, so re-set the quit flag
+ for later QUIT checking. */
+ set_quit_flag ();
+ }
+ catch (const gdb_exception_forced_quit &ex)
+ {
+ /* Like above, but (eventually) cause GDB to terminate by
+ setting sync_quit_force_run. */
+ set_force_quit_flag ();
+ }
catch (const gdb_exception &ex)
{
warning (_("Couldn't restore checkpoint state in %s: %s"),
diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index a17cf38a1f2..7752701378e 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -1271,6 +1271,14 @@ tui_getc (FILE *fp)
{
return tui_getc_1 (fp);
}
+ catch (const gdb_exception_forced_quit &ex)
+ {
+ /* As noted below, it's not safe to let an exception escape
+ to newline, so, for this case, reset the quit flag for
+ later QUIT checking. */
+ set_force_quit_flag ();
+ return 0;
+ }
catch (const gdb_exception &ex)
{
/* Just in case, don't ever let an exception escape to readline.
diff --git a/gdb/tui/tui.c b/gdb/tui/tui.c
index cdae9ffe02b..3604194a760 100644
--- a/gdb/tui/tui.c
+++ b/gdb/tui/tui.c
@@ -122,6 +122,13 @@ tui_rl_switch_mode (int notused1, int notused2)
tui_enable ();
}
}
+ catch (const gdb_exception_forced_quit &ex)
+ {
+ /* Ideally, we'd do a 'throw' here, but as noted above, we can't
+ do that, so, instead, we'll set the necessary flags so that
+ a later QUIT check will restart the forced quit. */
+ set_force_quit_flag ();
+ }
catch (const gdb_exception &ex)
{
exception_print (gdb_stderr, ex);
--
2.34.3
next prev parent reply other threads:[~2023-02-22 23:47 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-22 23:46 [PATCH v5 0/8] Fix gdb.base/gdb-sigterm.exp failure/error Kevin Buettner
2023-02-22 23:46 ` [PATCH v5 1/8] Introduce gdb_exception_forced_quit Kevin Buettner
2023-02-22 23:46 ` [PATCH v5 2/8] Handle gdb SIGTERM by throwing / catching gdb_exception_force_quit Kevin Buettner
2023-03-02 20:14 ` Simon Marchi
2023-02-22 23:46 ` [PATCH v5 3/8] Catch gdb_exception_error instead of gdb_exception (in many places) Kevin Buettner
2023-02-22 23:46 ` [PATCH v5 4/8] Python QUIT processing updates Kevin Buettner
2023-02-22 23:46 ` [PATCH v5 5/8] Guile " Kevin Buettner
2023-02-22 23:46 ` [PATCH v5 6/8] QUIT processing w/ explicit throw for gdb_exception_forced_quit Kevin Buettner
2023-02-22 23:46 ` [PATCH v5 7/8] Introduce set_force_quit_flag and change type of sync_quit_force_run Kevin Buettner
2023-02-22 23:46 ` Kevin Buettner [this message]
2023-02-23 13:01 ` [PATCH v5 0/8] Fix gdb.base/gdb-sigterm.exp failure/error Pedro Alves
2023-02-27 23:22 ` Kevin Buettner
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