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c45c3b4162
In PR gdb/32025, a fatal error was reported when sending a SIGINT to gdb while
disassembling.
I managed to reproduce this on aarch64-linux in a Leap 15.5 container using
this trigger patch:
...
gdb_disassembler_memory_reader::dis_asm_read_memory
(bfd_vma memaddr, gdb_byte *myaddr, unsigned int len,
struct disassemble_info *info) noexcept
{
+ set_quit_flag ();
return target_read_code (memaddr, myaddr, len);
}
...
and a simple gdb command line calling the disassemble command:
...
$ gdb -q -batch a.out -ex "disassemble main"
...
The following scenario leads to the fatal error:
- the disassemble command is executed,
- set_quit_flag is called in
gdb_disassembler_memory_reader::dis_asm_read_memory, pretending that a
user pressed ^C,
- target_read_code calls QUIT, which throws a
gdb_exception_quit,
- the exception propagation mechanism reaches c code in libopcodes and a fatal
error triggers because the c code is not compiled with -fexception.
Fix this by:
- wrapping the body of gdb_disassembler_memory_reader::dis_asm_read_memory in
catch_exceptions (which consequently needs moving to a header file), and
- reraising the caught exception in default_print_insn using QUIT.
Tested on aarch64-linux.
Approved-By: Andrew Burgess <aburgess@redhat.com>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32025
171 lines
5.2 KiB
C++
171 lines
5.2 KiB
C++
/* Definitions used by event-top.c, for GDB, the GNU debugger.
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Copyright (C) 1999-2024 Free Software Foundation, Inc.
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Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
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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 EVENT_TOP_H
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#define EVENT_TOP_H
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#include <signal.h>
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#include "extension.h"
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struct cmd_list_element;
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/* The current quit handler (and its type). This is called from the
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QUIT macro. See default_quit_handler below for default behavior.
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Parts of GDB temporarily override this to e.g., completely suppress
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Ctrl-C because it would not be safe to throw. E.g., normally, you
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wouldn't want to quit between a RSP command and its response, as
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that would break the communication with the target, but you may
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still want to intercept the Ctrl-C and offer to disconnect if the
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user presses Ctrl-C multiple times while the target is stuck
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waiting for the wedged remote stub. */
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typedef void (quit_handler_ftype) ();
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extern quit_handler_ftype *quit_handler;
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/* Exported functions from event-top.c.
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FIXME: these should really go into top.h. */
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/* The default quit handler. Checks whether Ctrl-C was pressed, and
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if so:
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- If GDB owns the terminal, throws a quit exception.
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- If GDB does not own the terminal, forwards the Ctrl-C to the
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target.
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*/
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extern void default_quit_handler ();
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/* Flag that function quit should call quit_force. */
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extern volatile bool sync_quit_force_run;
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/* Set sync_quit_force_run and also call set_quit_flag(). */
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extern void set_force_quit_flag ();
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/* Control C eventually causes this to be called, at a convenient time. */
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extern void quit ();
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/* Helper for the QUIT macro. */
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extern void maybe_quit ();
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/* Check whether a Ctrl-C was typed, and if so, call the current quit
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handler. */
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#define QUIT maybe_quit ()
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/* Set the serial event associated with the quit flag. */
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extern void quit_serial_event_set ();
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/* Clear the serial event associated with the quit flag. */
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extern void quit_serial_event_clear ();
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/* Wrap f (args) and handle exceptions by:
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- returning val, and
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- calling set_quit_flag or set_force_quit_flag, if needed. */
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template <typename R, R val, typename F, typename... Args>
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static R
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catch_exceptions (F &&f, Args&&... args)
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{
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try
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{
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return f (std::forward<Args> (args)...);
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}
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catch (const gdb_exception &ex)
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{
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if (ex.reason == RETURN_QUIT)
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set_quit_flag ();
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else if (ex.reason == RETURN_FORCED_QUIT)
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set_force_quit_flag ();
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}
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return val;
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}
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extern void display_gdb_prompt (const char *new_prompt);
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extern void gdb_setup_readline (int);
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extern void gdb_disable_readline (void);
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extern void gdb_init_signals (void);
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extern void change_line_handler (int);
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extern void command_line_handler (gdb::unique_xmalloc_ptr<char> &&rl);
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extern void command_handler (const char *command);
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#ifdef SIGTSTP
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extern void handle_sigtstp (int sig);
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#endif
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extern void handle_sigint (int sig);
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extern void handle_sigterm (int sig);
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extern void async_request_quit (void *arg);
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extern void async_disable_stdin (void);
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extern void async_enable_stdin (void);
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/* Exported variables from event-top.c.
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FIXME: these should really go into top.h. */
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extern bool set_editing_cmd_var;
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extern bool exec_done_display_p;
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extern struct prompts the_prompts;
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extern void (*after_char_processing_hook) (void);
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extern int call_stdin_event_handler_again_p;
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extern void gdb_readline_no_editing_callback (void *client_data);
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/* Wrappers for rl_callback_handler_remove and
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rl_callback_handler_install that keep track of whether the callback
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handler is installed in readline. Do not call the readline
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versions directly. */
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extern void gdb_rl_callback_handler_remove (void);
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extern void gdb_rl_callback_handler_install (const char *prompt);
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/* Reinstall the readline callback handler (with no prompt), if not
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currently installed. */
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extern void gdb_rl_callback_handler_reinstall (void);
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/* Called by readline after a complete line has been gathered from the
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user, but before the line is dispatched to back to GDB. This function
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is a wrapper around readline's builtin rl_deprep_terminal function, and
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handles the case where readline received EOF. */
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extern void gdb_rl_deprep_term_function (void);
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typedef void (*segv_handler_t) (int);
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/* On construction, replaces the current thread's SIGSEGV handler with
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the provided one. On destruction, restores the handler to the
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original one. */
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class scoped_segv_handler_restore
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{
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public:
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scoped_segv_handler_restore (segv_handler_t new_handler);
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~scoped_segv_handler_restore ();
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private:
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segv_handler_t m_old_handler;
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};
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#endif
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