Change cmake min version to 3.25.#42
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* Uses an older form for one feature that was introduced in 3.26. * Updates the docker image to install 3.25.2. Fixes #41.
ScottTodd
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Jan 31, 2025
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When building gdb with -O0 -fsanitize=address, and running test-case
gdb.ada/uninitialized_vars.exp, I run into:
...
(gdb) info locals
a = 0
z = (a => 1, b => false, c => 2.0)
=================================================================
==66372==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000097f58 at pc 0xffff52c0da1c bp 0xffffc90a1d40 sp 0xffffc90a1d80
READ of size 4 at 0x602000097f58 thread T0
#0 0xffff52c0da18 in memmove (/lib64/libasan.so.8+0x6da18)
#1 0xbcab24 in unsigned char* std::__copy_move_backward<false, true, std::random_access_iterator_tag>::__copy_move_b<unsigned char const, unsigned char>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:748
#2 0xbc9bf4 in unsigned char* std::__copy_move_backward_a2<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:769
#3 0xbc898c in unsigned char* std::__copy_move_backward_a1<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:778
#4 0xbc715c in unsigned char* std::__copy_move_backward_a<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:807
#5 0xbc4e6c in unsigned char* std::copy_backward<unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:867
#6 0xbc2934 in void gdb::copy<unsigned char const, unsigned char>(gdb::array_view<unsigned char const>, gdb::array_view<unsigned char>) gdb/../gdbsupport/array-view.h:223
#7 0x20e0100 in value::contents_copy_raw(value*, long, long, long) gdb/value.c:1239
#8 0x20e9830 in value::primitive_field(long, int, type*) gdb/value.c:3078
#9 0x20e98f8 in value_field(value*, int) gdb/value.c:3095
#10 0xcafd64 in print_field_values gdb/ada-valprint.c:658
#11 0xcb0fa0 in ada_val_print_struct_union gdb/ada-valprint.c:857
#12 0xcb1bb4 in ada_value_print_inner(value*, ui_file*, int, value_print_options const*) gdb/ada-valprint.c:1042
#13 0xc66e04 in ada_language::value_print_inner(value*, ui_file*, int, value_print_options const*) const (/home/vries/gdb/build/gdb/gdb+0xc66e04)
#14 0x20ca1e8 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1092
#15 0x20caabc in common_val_print_checked(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1184
#16 0x196c524 in print_variable_and_value(char const*, symbol*, frame_info_ptr, ui_file*, int) gdb/printcmd.c:2355
#17 0x1d99ca0 in print_variable_and_value_data::operator()(char const*, symbol*) gdb/stack.c:2308
#18 0x1dabca0 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::operator()(gdb::fv_detail::erased_callable, char const*, symbol*) const gdb/../gdbsupport/function-view.h:305
#19 0x1dabd14 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::_FUN(gdb::fv_detail::erased_callable, char const*, symbol*) gdb/../gdbsupport/function-view.h:299
#20 0x1dab34c in gdb::function_view<void (char const*, symbol*)>::operator()(char const*, symbol*) const gdb/../gdbsupport/function-view.h:289
#21 0x1d9963c in iterate_over_block_locals gdb/stack.c:2240
#22 0x1d99790 in iterate_over_block_local_vars(block const*, gdb::function_view<void (char const*, symbol*)>) gdb/stack.c:2259
#23 0x1d9a598 in print_frame_local_vars gdb/stack.c:2380
#24 0x1d9afac in info_locals_command(char const*, int) gdb/stack.c:2458
#25 0xfd7b30 in do_simple_func gdb/cli/cli-decode.c:95
#26 0xfe5a2c in cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735
#27 0x1f03790 in execute_command(char const*, int) gdb/top.c:575
#28 0x1384080 in command_handler(char const*) gdb/event-top.c:566
#29 0x1384e2c in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:802
#30 0x1f731e4 in tui_command_line_handler gdb/tui/tui-interp.c:104
#31 0x1382a58 in gdb_rl_callback_handler gdb/event-top.c:259
#32 0x21dbb80 in rl_callback_read_char readline/readline/callback.c:290
#33 0x1382510 in gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195
#34 0x138277c in gdb_rl_callback_read_char_wrapper gdb/event-top.c:234
#35 0x1fe9b40 in stdin_event_handler gdb/ui.c:155
#36 0x35ff1bc in handle_file_event gdbsupport/event-loop.cc:573
#37 0x35ff9d8 in gdb_wait_for_event gdbsupport/event-loop.cc:694
#38 0x35fd284 in gdb_do_one_event(int) gdbsupport/event-loop.cc:264
#39 0x1768080 in start_event_loop gdb/main.c:408
#40 0x17684c4 in captured_command_loop gdb/main.c:472
#41 0x176cfc8 in captured_main gdb/main.c:1342
#42 0x176d088 in gdb_main(captured_main_args*) gdb/main.c:1361
#43 0xb73edc in main gdb/gdb.c:39
#44 0xffff519b09d8 in __libc_start_call_main (/lib64/libc.so.6+0x309d8)
#45 0xffff519b0aac in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x30aac)
#46 0xb73c2c in _start (/home/vries/gdb/build/gdb/gdb+0xb73c2c)
0x602000097f58 is located 0 bytes after 8-byte region [0x602000097f50,0x602000097f58)
allocated by thread T0 here:
#0 0xffff52c65218 in calloc (/lib64/libasan.so.8+0xc5218)
#1 0xcbc278 in xcalloc gdb/alloc.c:97
#2 0x35f21e8 in xzalloc(unsigned long) gdbsupport/common-utils.cc:29
#3 0x20de270 in value::allocate_contents(bool) gdb/value.c:937
#4 0x20edc08 in value::fetch_lazy() gdb/value.c:4033
#5 0x20dadc0 in value::entirely_covered_by_range_vector(std::vector<range, std::allocator<range> > const&) gdb/value.c:229
#6 0xcb2298 in value::entirely_optimized_out() gdb/value.h:560
#7 0x20ca6fc in value_check_printable gdb/valprint.c:1133
#8 0x20caa8c in common_val_print_checked(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1182
#9 0x196c524 in print_variable_and_value(char const*, symbol*, frame_info_ptr, ui_file*, int) gdb/printcmd.c:2355
#10 0x1d99ca0 in print_variable_and_value_data::operator()(char const*, symbol*) gdb/stack.c:2308
#11 0x1dabca0 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::operator()(gdb::fv_detail::erased_callable, char const*, symbol*) const gdb/../gdbsupport/function-view.h:305
#12 0x1dabd14 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::_FUN(gdb::fv_detail::erased_callable, char const*, symbol*) gdb/../gdbsupport/function-view.h:299
#13 0x1dab34c in gdb::function_view<void (char const*, symbol*)>::operator()(char const*, symbol*) const gdb/../gdbsupport/function-view.h:289
#14 0x1d9963c in iterate_over_block_locals gdb/stack.c:2240
#15 0x1d99790 in iterate_over_block_local_vars(block const*, gdb::function_view<void (char const*, symbol*)>) gdb/stack.c:2259
#16 0x1d9a598 in print_frame_local_vars gdb/stack.c:2380
#17 0x1d9afac in info_locals_command(char const*, int) gdb/stack.c:2458
#18 0xfd7b30 in do_simple_func gdb/cli/cli-decode.c:95
#19 0xfe5a2c in cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735
#20 0x1f03790 in execute_command(char const*, int) gdb/top.c:575
#21 0x1384080 in command_handler(char const*) gdb/event-top.c:566
#22 0x1384e2c in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:802
#23 0x1f731e4 in tui_command_line_handler gdb/tui/tui-interp.c:104
#24 0x1382a58 in gdb_rl_callback_handler gdb/event-top.c:259
#25 0x21dbb80 in rl_callback_read_char readline/readline/callback.c:290
#26 0x1382510 in gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195
#27 0x138277c in gdb_rl_callback_read_char_wrapper gdb/event-top.c:234
#28 0x1fe9b40 in stdin_event_handler gdb/ui.c:155
#29 0x35ff1bc in handle_file_event gdbsupport/event-loop.cc:573
SUMMARY: AddressSanitizer: heap-buffer-overflow (/lib64/libasan.so.8+0x6da18) in memmove
...
The error happens when trying to print either variable y or y2:
...
type Variable_Record (A : Boolean := True) is record
case A is
when True =>
B : Integer;
when False =>
C : Float;
D : Integer;
end case;
end record;
Y : Variable_Record := (A => True, B => 1);
Y2 : Variable_Record := (A => False, C => 1.0, D => 2);
...
when the variables are uninitialized.
The error happens only when printing the entire variable:
...
(gdb) p y.a
$2 = 216
(gdb) p y.b
There is no member named b.
(gdb) p y.c
$3 = 9.18340949e-41
(gdb) p y.d
$4 = 1
(gdb) p y
<AddressSanitizer: heap-buffer-overflow>
...
The error happens as follows:
- field a functions as discriminant, choosing either the b, or c+d variant.
- when y.a happens to be set to 216, as above, gdb interprets this as the
variable having the c+d variant (which is why trying to print y.b fails).
- when printing y, gdb allocates a value, copies the bytes into it from the
target, and then prints the value.
- gdb allocates the value using the type size, which is 8. It's 8 because
that's what the DW_AT_byte_size indicates. Note that for valid values of a,
it gives correct results: if a is 0 (c+d variant), size is 12, if a is 1
(b variant), size is 8.
- gdb tries to print field d, which is at an 8 byte offset, and that results
in a out-of-bounds access for the allocated 8-byte value.
Fix this by handling this case in value::contents_copy_raw, such that we have:
...
(gdb) p y
$1 = (a => 24, c => 9.18340949e-41,
d => <error reading variable: access outside bounds of object>)
...
An alternative (additional) fix could be this: in compute_variant_fields_inner
gdb reads the discriminant y.a to decide which variant is active. It would be
nice to detect that the value (y.a == 24) is not a valid Boolean, and give up
on choosing a variant altoghether. However, the situation regarding the
internal type CODE_TYPE_BOOL is currently ambiguous (see PR31282) and it's not
possible to reliably decide what valid values are.
The test-case source file gdb.ada/uninitialized-variable-record/parse.adb is
a reduced version of gdb.ada/uninitialized_vars/parse.adb, so it copies the
copyright years.
Note that the test-case needs gcc-12 or newer, it's unsupported for older gcc
versions. [ So, it would be nice to rewrite it into a dwarf assembly
test-case. ]
The test-case loops over all languages. This is inherited from an earlier
attempt to fix this, which had language-specific fixes (in print_field_values,
cp_print_value_fields, pascal_object_print_value_fields and
f_language::value_print_inner). I've left this in, but I suppose it's not
strictly necessary anymore.
Tested on x86_64-linux.
PR exp/31258
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31258
subbul-amd
pushed a commit
that referenced
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Apr 28, 2026
From the Python API, we can execute GDB commands via gdb.execute. If the command gives an exception, however, we need to recover the GDB prompt and enable stdin, because the exception does not reach top-level GDB or normal_stop. This was done in commit commit 1ba1ac8 Author: Andrew Burgess <andrew.burgess@embecosm.com> Date: Tue Nov 19 11:17:20 2019 +0000 gdb: Enable stdin on exception in execute_gdb_command with the following code: catch (const gdb_exception &except) { /* If an exception occurred then we won't hit normal_stop (), or have an exception reach the top level of the event loop, which are the two usual places in which stdin would be re-enabled. So, before we convert the exception and continue back in Python, we should re-enable stdin here. */ async_enable_stdin (); GDB_PY_HANDLE_EXCEPTION (except); } In this patch, we explain what happens when we run a GDB command in the context of a synchronous command, e.g. via Python observer notifications. As an example, suppose we have the following objfile event listener, specified in a file named file.py: ~~~ import gdb class MyListener: def __init__(self): gdb.events.new_objfile.connect(self.handle_new_objfile_event) self.processed_objfile = False def handle_new_objfile_event(self, event): if self.processed_objfile: return print("loading " + event.new_objfile.filename) self.processed_objfile = True gdb.execute('add-inferior -no-connection') gdb.execute('inferior 2') gdb.execute('target remote | gdbserver - /tmp/a.out') gdb.execute('inferior 1') the_listener = MyListener() ~~~ Using this Python file, we see the behavior below: $ gdb -q -ex "source file.py" -ex "run" --args a.out Reading symbols from a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 [New inferior 2] Added inferior 2 [Switching to inferior 2 [<null>] (<noexec>)] stdin/stdout redirected Process /tmp/a.out created; pid = 3075406 Remote debugging using stdio Reading /tmp/a.out from remote target... ... [Switching to inferior 1 [process 3075400] (/tmp/a.out)] [Switching to thread 1.1 (process 3075400)] #0 0x00007ffff7fe3290 in ?? () from /lib64/ld-linux-x86-64.so.2 (gdb) [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [Inferior 1 (process 3075400) exited normally] Note how the GDB prompt comes in-between the debugger output. We have this obscure behavior, because the executed command, "target remote", triggers an invocation of `normal_stop` that enables stdin. After that, however, the Python notification context completes and GDB continues with its normal flow of executing the 'run' command. This can be seen in the call stack below: (top-gdb) bt #0 async_enable_stdin () at src/gdb/event-top.c:523 #1 0x00005555561c3acd in normal_stop () at src/gdb/infrun.c:9432 #2 0x00005555561b328e in start_remote (from_tty=0) at src/gdb/infrun.c:3801 #3 0x0000555556441224 in remote_target::start_remote_1 (this=0x5555587882e0, from_tty=0, extended_p=0) at src/gdb/remote.c:5225 #4 0x000055555644166c in remote_target::start_remote (this=0x5555587882e0, from_tty=0, extended_p=0) at src/gdb/remote.c:5316 #5 0x00005555564430cf in remote_target::open_1 (name=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0, extended_p=0) at src/gdb/remote.c:6175 #6 0x0000555556441707 in remote_target::open (name=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0) at src/gdb/remote.c:5338 #7 0x00005555565ea63f in open_target (args=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0, command=0x555558589280) at src/gdb/target.c:824 #8 0x0000555555f0d89a in cmd_func (cmd=0x555558589280, args=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0) at src/gdb/cli/cli-decode.c:2735 #9 0x000055555661fb42 in execute_command (p=0x55555878529e "t", from_tty=0) at src/gdb/top.c:575 #10 0x0000555555f1a506 in execute_control_command_1 (cmd=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:529 #11 0x0000555555f1abea in execute_control_command (cmd=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:701 #12 0x0000555555f19fc7 in execute_control_commands (cmdlines=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:411 #13 0x0000555556400d91 in execute_gdb_command (self=0x7ffff43b5d00, args=0x7ffff440ab60, kw=0x0) at src/gdb/python/python.c:700 #14 0x00007ffff7a96023 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #15 0x00007ffff7a4dadc in _PyObject_MakeTpCall () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #16 0x00007ffff79e9a1c in _PyEval_EvalFrameDefault () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #17 0x00007ffff7b303af in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #18 0x00007ffff7a50358 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #19 0x00007ffff7a4f3f4 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #20 0x00007ffff7a4f883 in PyObject_CallFunctionObjArgs () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #21 0x00005555563a9758 in evpy_emit_event (event=0x7ffff42b5430, registry=0x7ffff42b4690) at src/gdb/python/py-event.c:104 #22 0x00005555563cb874 in emit_new_objfile_event (objfile=0x555558761700) at src/gdb/python/py-newobjfileevent.c:52 #23 0x00005555563b53bc in python_new_objfile (objfile=0x555558761700) at src/gdb/python/py-inferior.c:195 #24 0x0000555555d6dff0 in std::__invoke_impl<void, void (*&)(objfile*), objfile*> (__f=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:61 #25 0x0000555555d6be18 in std::__invoke_r<void, void (*&)(objfile*), objfile*> (__fn=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:111 #26 0x0000555555d69661 in std::_Function_handler<void (objfile*), void (*)(objfile*)>::_M_invoke(std::_Any_data const&, objfile*&&) (__functor=..., __args#0=@0x7fffffffd080: 0x555558761700) at /usr/include/c++/11/bits/std_function.h:290 #27 0x0000555556314caf in std::function<void (objfile*)>::operator()(objfile*) const (this=0x5555585b5860, __args#0=0x555558761700) at /usr/include/c++/11/bits/std_function.h:590 #28 0x000055555631444e in gdb::observers::observable<objfile*>::notify (this=0x55555836eea0 <gdb::observers::new_objfile>, args#0=0x555558761700) at src/gdb/../gdbsupport/observable.h:166 #29 0x0000555556599b3f in symbol_file_add_with_addrs (abfd=..., name=0x55555875d310 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1125 #30 0x0000555556599ca4 in symbol_file_add_from_bfd (abfd=..., name=0x55555875d310 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1160 #31 0x0000555556546371 in solib_read_symbols (so=..., flags=...) at src/gdb/solib.c:692 #32 0x0000555556546f0f in solib_add (pattern=0x0, from_tty=0, readsyms=1) at src/gdb/solib.c:1015 #33 0x0000555556539891 in enable_break (info=0x55555874e180, from_tty=0) at src/gdb/solib-svr4.c:2416 #34 0x000055555653b305 in svr4_solib_create_inferior_hook (from_tty=0) at src/gdb/solib-svr4.c:3058 #35 0x0000555556547cee in solib_create_inferior_hook (from_tty=0) at src/gdb/solib.c:1217 #36 0x0000555556196f6a in post_create_inferior (from_tty=0) at src/gdb/infcmd.c:275 #37 0x0000555556197670 in run_command_1 (args=0x0, from_tty=1, run_how=RUN_NORMAL) at src/gdb/infcmd.c:486 #38 0x000055555619783f in run_command (args=0x0, from_tty=1) at src/gdb/infcmd.c:512 #39 0x0000555555f0798d in do_simple_func (args=0x0, from_tty=1, c=0x555558567510) at src/gdb/cli/cli-decode.c:95 #40 0x0000555555f0d89a in cmd_func (cmd=0x555558567510, args=0x0, from_tty=1) at src/gdb/cli/cli-decode.c:2735 #41 0x000055555661fb42 in execute_command (p=0x7fffffffe2c4 "", from_tty=1) at src/gdb/top.c:575 #42 0x000055555626303b in catch_command_errors (command=0x55555661f4ab <execute_command(char const*, int)>, arg=0x7fffffffe2c1 "run", from_tty=1, do_bp_actions=true) at src/gdb/main.c:513 #43 0x000055555626328a in execute_cmdargs (cmdarg_vec=0x7fffffffdaf0, file_type=CMDARG_FILE, cmd_type=CMDARG_COMMAND, ret=0x7fffffffda3c) at src/gdb/main.c:612 #44 0x0000555556264849 in captured_main_1 (context=0x7fffffffdd40) at src/gdb/main.c:1293 #45 0x0000555556264a7f in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1314 #46 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343 #47 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39 (top-gdb) The use of the "target remote" command here is just an example. In principle, we would reproduce the problem with any command that triggers an invocation of `normal_stop`. To omit enabling the stdin in `normal_stop`, we would have to check the context we are in. Since we cannot do that, we add a new field to `struct ui` to track whether the prompt was already blocked, and set the tracker flag in the Python context before executing a GDB command. After applying this patch, the output becomes ... Reading symbols from a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 [New inferior 2] Added inferior 2 [Switching to inferior 2 [<null>] (<noexec>)] stdin/stdout redirected Process /tmp/a.out created; pid = 3032261 Remote debugging using stdio Reading /tmp/a.out from remote target... ... [Switching to inferior 1 [process 3032255] (/tmp/a.out)] [Switching to thread 1.1 (process 3032255)] #0 0x00007ffff7fe3290 in ?? () from /lib64/ld-linux-x86-64.so.2 [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [Inferior 1 (process 3032255) exited normally] (gdb) Let's now consider a secondary scenario, where the command executed from the Python raises an error. As an example, suppose we have the Python file below: def handle_new_objfile_event(self, event): ... print("loading " + event.new_objfile.filename) self.processed_objfile = True gdb.execute('print a') The executed command, "print a", gives an error because "a" is not defined. Without this patch, we see the behavior below, where the prompt is again placed incorrectly: ... Reading symbols from /tmp/a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 Python Exception <class 'gdb.error'>: No symbol "a" in current context. (gdb) [Inferior 1 (process 3980401) exited normally] This time, `async_enable_stdin` is called from the 'catch' block in `execute_gdb_command`: (top-gdb) bt #0 async_enable_stdin () at src/gdb/event-top.c:523 #1 0x0000555556400f0a in execute_gdb_command (self=0x7ffff43b5d00, args=0x7ffff440ab60, kw=0x0) at src/gdb/python/python.c:713 #2 0x00007ffff7a96023 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #3 0x00007ffff7a4dadc in _PyObject_MakeTpCall () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #4 0x00007ffff79e9a1c in _PyEval_EvalFrameDefault () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #5 0x00007ffff7b303af in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #6 0x00007ffff7a50358 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #7 0x00007ffff7a4f3f4 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #8 0x00007ffff7a4f883 in PyObject_CallFunctionObjArgs () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #9 0x00005555563a9758 in evpy_emit_event (event=0x7ffff42b5430, registry=0x7ffff42b4690) at src/gdb/python/py-event.c:104 #10 0x00005555563cb874 in emit_new_objfile_event (objfile=0x555558761410) at src/gdb/python/py-newobjfileevent.c:52 #11 0x00005555563b53bc in python_new_objfile (objfile=0x555558761410) at src/gdb/python/py-inferior.c:195 #12 0x0000555555d6dff0 in std::__invoke_impl<void, void (*&)(objfile*), objfile*> (__f=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:61 #13 0x0000555555d6be18 in std::__invoke_r<void, void (*&)(objfile*), objfile*> (__fn=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:111 #14 0x0000555555d69661 in std::_Function_handler<void (objfile*), void (*)(objfile*)>::_M_invoke(std::_Any_data const&, objfile*&&) (__functor=..., __args#0=@0x7fffffffd080: 0x555558761410) at /usr/include/c++/11/bits/std_function.h:290 #15 0x0000555556314caf in std::function<void (objfile*)>::operator()(objfile*) const (this=0x5555585b5860, __args#0=0x555558761410) at /usr/include/c++/11/bits/std_function.h:590 #16 0x000055555631444e in gdb::observers::observable<objfile*>::notify (this=0x55555836eea0 <gdb::observers::new_objfile>, args#0=0x555558761410) at src/gdb/../gdbsupport/observable.h:166 #17 0x0000555556599b3f in symbol_file_add_with_addrs (abfd=..., name=0x55555875d020 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1125 #18 0x0000555556599ca4 in symbol_file_add_from_bfd (abfd=..., name=0x55555875d020 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1160 #19 0x0000555556546371 in solib_read_symbols (so=..., flags=...) at src/gdb/solib.c:692 #20 0x0000555556546f0f in solib_add (pattern=0x0, from_tty=0, readsyms=1) at src/gdb/solib.c:1015 #21 0x0000555556539891 in enable_break (info=0x55555874a670, from_tty=0) at src/gdb/solib-svr4.c:2416 #22 0x000055555653b305 in svr4_solib_create_inferior_hook (from_tty=0) at src/gdb/solib-svr4.c:3058 #23 0x0000555556547cee in solib_create_inferior_hook (from_tty=0) at src/gdb/solib.c:1217 #24 0x0000555556196f6a in post_create_inferior (from_tty=0) at src/gdb/infcmd.c:275 #25 0x0000555556197670 in run_command_1 (args=0x0, from_tty=1, run_how=RUN_NORMAL) at src/gdb/infcmd.c:486 #26 0x000055555619783f in run_command (args=0x0, from_tty=1) at src/gdb/infcmd.c:512 #27 0x0000555555f0798d in do_simple_func (args=0x0, from_tty=1, c=0x555558567510) at src/gdb/cli/cli-decode.c:95 #28 0x0000555555f0d89a in cmd_func (cmd=0x555558567510, args=0x0, from_tty=1) at src/gdb/cli/cli-decode.c:2735 #29 0x000055555661fb42 in execute_command (p=0x7fffffffe2c4 "", from_tty=1) at src/gdb/top.c:575 #30 0x000055555626303b in catch_command_errors (command=0x55555661f4ab <execute_command(char const*, int)>, arg=0x7fffffffe2c1 "run", from_tty=1, do_bp_actions=true) at src/gdb/main.c:513 #31 0x000055555626328a in execute_cmdargs (cmdarg_vec=0x7fffffffdaf0, file_type=CMDARG_FILE, cmd_type=CMDARG_COMMAND, ret=0x7fffffffda3c) at src/gdb/main.c:612 #32 0x0000555556264849 in captured_main_1 (context=0x7fffffffdd40) at src/gdb/main.c:1293 #33 0x0000555556264a7f in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1314 #34 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343 #35 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39 (top-gdb) Again, after we enable stdin, GDB continues with its normal flow of the 'run' command and receives the inferior's exit event, where it would have enabled stdin, if we had not done it prematurely. (top-gdb) bt #0 async_enable_stdin () at src/gdb/event-top.c:523 #1 0x00005555561c3acd in normal_stop () at src/gdb/infrun.c:9432 #2 0x00005555561b5bf1 in fetch_inferior_event () at src/gdb/infrun.c:4700 #3 0x000055555618d6a7 in inferior_event_handler (event_type=INF_REG_EVENT) at src/gdb/inf-loop.c:42 #4 0x000055555620ecdb in handle_target_event (error=0, client_data=0x0) at src/gdb/linux-nat.c:4316 #5 0x0000555556f33035 in handle_file_event (file_ptr=0x5555587024e0, ready_mask=1) at src/gdbsupport/event-loop.cc:573 #6 0x0000555556f3362f in gdb_wait_for_event (block=0) at src/gdbsupport/event-loop.cc:694 #7 0x0000555556f322cd in gdb_do_one_event (mstimeout=-1) at src/gdbsupport/event-loop.cc:217 #8 0x0000555556262df8 in start_event_loop () at src/gdb/main.c:407 #9 0x0000555556262f85 in captured_command_loop () at src/gdb/main.c:471 #10 0x0000555556264a84 in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1324 #11 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343 #12 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39 (top-gdb) The solution implemented by this patch addresses the problem. After applying the patch, the output becomes $ gdb -q -ex "source file.py" -ex "run" --args a.out Reading symbols from /tmp/a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 Python Exception <class 'gdb.error'>: No symbol "a" in current context. [Inferior 1 (process 3984511) exited normally] (gdb) Regression-tested on X86_64 Linux using the default board file (i.e. unix). Co-Authored-By: Oguzhan Karakaya <oguzhan.karakaya@intel.com> Reviewed-By: Guinevere Larsen <blarsen@redhat.com> Approved-By: Tom Tromey <tom@tromey.com>
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When running test-case gdb.server/connect-with-no-symbol-file.exp on aarch64-linux (specifically, an opensuse leap 15.5 container on a fedora asahi 39 system), I run into: ... (gdb) detach^M Detaching from program: target:connect-with-no-symbol-file, process 185104^M Ending remote debugging.^M terminate called after throwing an instance of 'gdb_exception_error'^M ... The detailed backtrace of the corefile is: ... (gdb) bt #0 0x0000ffff75504f54 in raise () from /lib64/libpthread.so.0 #1 0x00000000007a86b4 in handle_fatal_signal (sig=6) at gdb/event-top.c:926 #2 <signal handler called> #3 0x0000ffff74b977b4 in raise () from /lib64/libc.so.6 #4 0x0000ffff74b98c18 in abort () from /lib64/libc.so.6 #5 0x0000ffff74ea26f4 in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib64/libstdc++.so.6 #6 0x0000ffff74ea011c in ?? () from /usr/lib64/libstdc++.so.6 #7 0x0000ffff74ea0180 in std::terminate() () from /usr/lib64/libstdc++.so.6 #8 0x0000ffff74ea0464 in __cxa_throw () from /usr/lib64/libstdc++.so.6 #9 0x0000000001548870 in throw_it (reason=RETURN_ERROR, error=TARGET_CLOSE_ERROR, fmt=0x16c7810 "Remote connection closed", ap=...) at gdbsupport/common-exceptions.cc:203 #10 0x0000000001548920 in throw_verror (error=TARGET_CLOSE_ERROR, fmt=0x16c7810 "Remote connection closed", ap=...) at gdbsupport/common-exceptions.cc:211 #11 0x0000000001548a00 in throw_error (error=TARGET_CLOSE_ERROR, fmt=0x16c7810 "Remote connection closed") at gdbsupport/common-exceptions.cc:226 #12 0x0000000000ac8f2c in remote_target::readchar (this=0x233d3d90, timeout=2) at gdb/remote.c:9856 #13 0x0000000000ac9f04 in remote_target::getpkt (this=0x233d3d90, buf=0x233d40a8, forever=false, is_notif=0x0) at gdb/remote.c:10326 #14 0x0000000000acf3d0 in remote_target::remote_hostio_send_command (this=0x233d3d90, command_bytes=13, which_packet=17, remote_errno=0xfffff1a3cf38, attachment=0xfffff1a3ce88, attachment_len=0xfffff1a3ce90) at gdb/remote.c:12567 #15 0x0000000000ad03bc in remote_target::fileio_fstat (this=0x233d3d90, fd=3, st=0xfffff1a3d020, remote_errno=0xfffff1a3cf38) at gdb/remote.c:12979 #16 0x0000000000c39878 in target_fileio_fstat (fd=0, sb=0xfffff1a3d020, target_errno=0xfffff1a3cf38) at gdb/target.c:3315 #17 0x00000000007eee5c in target_fileio_stream::stat (this=0x233d4400, abfd=0x2323fc40, sb=0xfffff1a3d020) at gdb/gdb_bfd.c:467 #18 0x00000000007f012c in <lambda(bfd*, void*, stat*)>::operator()(bfd *, void *, stat *) const (__closure=0x0, abfd=0x2323fc40, stream=0x233d4400, sb=0xfffff1a3d020) at gdb/gdb_bfd.c:955 #19 0x00000000007f015c in <lambda(bfd*, void*, stat*)>::_FUN(bfd *, void *, stat *) () at gdb/gdb_bfd.c:956 #20 0x0000000000f9b838 in opncls_bstat (abfd=0x2323fc40, sb=0xfffff1a3d020) at bfd/opncls.c:665 #21 0x0000000000f90adc in bfd_stat (abfd=0x2323fc40, statbuf=0xfffff1a3d020) at bfd/bfdio.c:431 #22 0x000000000065fe20 in reopen_exec_file () at gdb/corefile.c:52 #23 0x0000000000c3a3e8 in generic_mourn_inferior () at gdb/target.c:3642 #24 0x0000000000abf3f0 in remote_unpush_target (target=0x233d3d90) at gdb/remote.c:6067 #25 0x0000000000aca8b0 in remote_target::mourn_inferior (this=0x233d3d90) at gdb/remote.c:10587 #26 0x0000000000c387cc in target_mourn_inferior ( ptid=<error reading variable: Cannot access memory at address 0x2d310>) at gdb/target.c:2738 #27 0x0000000000abfff0 in remote_target::remote_detach_1 (this=0x233d3d90, inf=0x22fce540, from_tty=1) at gdb/remote.c:6421 #28 0x0000000000ac0094 in remote_target::detach (this=0x233d3d90, inf=0x22fce540, from_tty=1) at gdb/remote.c:6436 #29 0x0000000000c37c3c in target_detach (inf=0x22fce540, from_tty=1) at gdb/target.c:2526 #30 0x0000000000860424 in detach_command (args=0x0, from_tty=1) at gdb/infcmd.c:2817 #31 0x000000000060b594 in do_simple_func (args=0x0, from_tty=1, c=0x231431a0) at gdb/cli/cli-decode.c:94 #32 0x00000000006108c8 in cmd_func (cmd=0x231431a0, args=0x0, from_tty=1) at gdb/cli/cli-decode.c:2741 #33 0x0000000000c65a94 in execute_command (p=0x232e52f6 "", from_tty=1) at gdb/top.c:570 #34 0x00000000007a7d2c in command_handler (command=0x232e52f0 "") at gdb/event-top.c:566 #35 0x00000000007a8290 in command_line_handler (rl=...) at gdb/event-top.c:802 #36 0x0000000000c9092c in tui_command_line_handler (rl=...) at gdb/tui/tui-interp.c:103 #37 0x00000000007a750c in gdb_rl_callback_handler (rl=0x23385330 "detach") at gdb/event-top.c:258 #38 0x0000000000d910f4 in rl_callback_read_char () at readline/readline/callback.c:290 #39 0x00000000007a7338 in gdb_rl_callback_read_char_wrapper_noexcept () at gdb/event-top.c:194 #40 0x00000000007a73f0 in gdb_rl_callback_read_char_wrapper (client_data=0x22fbf640) at gdb/event-top.c:233 #41 0x0000000000cbee1c in stdin_event_handler (error=0, client_data=0x22fbf640) at gdb/ui.c:154 #42 0x000000000154ed60 in handle_file_event (file_ptr=0x232be730, ready_mask=1) at gdbsupport/event-loop.cc:572 #43 0x000000000154f21c in gdb_wait_for_event (block=1) at gdbsupport/event-loop.cc:693 #44 0x000000000154dec4 in gdb_do_one_event (mstimeout=-1) at gdbsupport/event-loop.cc:263 #45 0x0000000000910f98 in start_event_loop () at gdb/main.c:400 #46 0x0000000000911130 in captured_command_loop () at gdb/main.c:464 #47 0x0000000000912b5c in captured_main (data=0xfffff1a3db58) at gdb/main.c:1338 #48 0x0000000000912bf4 in gdb_main (args=0xfffff1a3db58) at gdb/main.c:1357 #49 0x00000000004170f4 in main (argc=10, argv=0xfffff1a3dcc8) at gdb/gdb.c:38 (gdb) ... The abort happens because a c++ exception escapes to c code, specifically opncls_bstat in bfd/opncls.c. Compiling with -fexceptions works around this. Fix this by catching the exception just before it escapes, in stat_trampoline and likewise in few similar spot. Add a new template catch_exceptions to do so in a consistent way. Tested on aarch64-linux. Approved-by: Pedro Alves <pedro@palves.net> PR remote/31577 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31577
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…rget_breakpoint::check_status
ROCgdb handles target events very slowly when running a test case like
this, where a breakpoint is preset on HipTest::vectorADD:
for (int i=0; i < numDevices; ++i) {
HIPCHECK(hipSetDevice(i));
hipLaunchKernelGGL(HipTest::vectorADD, dim3(blocks), dim3(threadsPerBlock), 0, stream[i],
static_cast<const int*>(A_d[i]), static_cast<const int*>(B_d[i]), C_d[i], N);
}
What happens is:
- A kernel is launched
- The internal runtime breakpoint is hit during the second
hipLaunchKernelGGL call, which causes
amd_dbgapi_target_breakpoint::check_status to be called
- Meanwhile, all waves of the kernel hit the breakpoint on vectorADD
- amd_dbgapi_target_breakpoint::check_status calls process_event_queue,
which pulls the thousand of breakpoint hit events from the kernel
- As part of handling the breakpoint hit events, we write the PC of the
waves that stopped to decrement it. Because the forward progress
requirement is not disabled, this causes a suspend/resume of the
queue each time, which is time-consuming.
The stack trace where this all happens is:
#32 0x00007ffff6b9abda in amd_dbgapi_write_register (wave_id=..., register_id=..., offset=0, value_size=8, value=0x7fffea9fdcc0) at /home/smarchi/src/amd-dbgapi/src/register.cpp:587
#33 0x00005555588c0bed in amd_dbgapi_target::store_registers (this=0x55555c7b1d20 <the_amd_dbgapi_target>, regcache=0x507000002240, regno=470) at /home/smarchi/src/wt/amd/gdb/amd-dbgapi-target.c:2504
#34 0x000055555a5186a1 in target_store_registers (regcache=0x507000002240, regno=470) at /home/smarchi/src/wt/amd/gdb/target.c:3973
#35 0x0000555559fab831 in regcache::raw_write (this=0x507000002240, regnum=470, src=...) at /home/smarchi/src/wt/amd/gdb/regcache.c:890
#36 0x0000555559fabd2b in regcache::cooked_write (this=0x507000002240, regnum=470, src=...) at /home/smarchi/src/wt/amd/gdb/regcache.c:915
#37 0x0000555559fc3ca5 in regcache::cooked_write<unsigned long, void> (this=0x507000002240, regnum=470, val=140737323456768) at /home/smarchi/src/wt/amd/gdb/regcache.c:850
#38 0x0000555559fab09a in regcache_cooked_write_unsigned (regcache=0x507000002240, regnum=470, val=140737323456768) at /home/smarchi/src/wt/amd/gdb/regcache.c:858
#39 0x0000555559fb0678 in regcache_write_pc (regcache=0x507000002240, pc=0x7ffff62bd900) at /home/smarchi/src/wt/amd/gdb/regcache.c:1460
#40 0x00005555588bb37d in process_one_event (event_id=..., event_kind=AMD_DBGAPI_EVENT_KIND_WAVE_STOP) at /home/smarchi/src/wt/amd/gdb/amd-dbgapi-target.c:1873
#41 0x00005555588bbf7b in process_event_queue (process_id=..., until_event_kind=AMD_DBGAPI_EVENT_KIND_BREAKPOINT_RESUME) at /home/smarchi/src/wt/amd/gdb/amd-dbgapi-target.c:2006
#42 0x00005555588b1aca in amd_dbgapi_target_breakpoint::check_status (this=0x511000140900, bs=0x50600014ed00) at /home/smarchi/src/wt/amd/gdb/amd-dbgapi-target.c:890
#43 0x0000555558c50080 in bpstat_stop_status (aspace=0x5070000061b0, bp_addr=0x7fffed0b9ab0, thread=0x518000026c80, ws=..., stop_chain=0x50600014ed00) at /home/smarchi/src/wt/amd/gdb/breakpoint.c:6126
#44 0x000055555984f4ff in handle_signal_stop (ecs=0x7fffeaa40ef0) at /home/smarchi/src/wt/amd/gdb/infrun.c:7169
#45 0x000055555984b889 in handle_inferior_event (ecs=0x7fffeaa40ef0) at /home/smarchi/src/wt/amd/gdb/infrun.c:6621
#46 0x000055555983eab6 in fetch_inferior_event () at /home/smarchi/src/wt/amd/gdb/infrun.c:4750
#47 0x00005555597caa5f in inferior_event_handler (event_type=INF_REG_EVENT) at /home/smarchi/src/wt/amd/gdb/inf-loop.c:42
#48 0x00005555588b838e in handle_target_event (client_data=0x0) at /home/smarchi/src/wt/amd/gdb/amd-dbgapi-target.c:1513
Fix that performance problem by disabling the forward progress
requirement in amd_dbgapi_target_breakpoint::check_status, before
calling process_event_queue, so that we can process all events
efficiently.
Since the same performance problem could theoritically happen any time
process_event_queue is called with forward progress requirement enabled,
add an assert to ensure that forward progress requirement is disabled
when process_event_queue is invoked. This makes it necessary to add a
require_forward_progress call to amd_dbgapi_finalize_core_attach. It
looks a bit strange, since core files don't have execution, but it
doesn't hurt.
Add a test that replicates this scenario. The test launches a kernel
that hits a breakpoint (with an always false condition) repeatedly.
Meanwhile, the host process loads an unloads a code object, causing
check_status to be called.
Bug: SWDEV-482511
Change-Id: Ida86340d679e6bd8462712953458c07ba3fd49ec
Approved-by: Lancelot Six <lancelot.six@amd.com>
(cherry picked from commit bb7c679902ece35d1427a88e9a79305544b009e1)
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Fixes #41.