This commit builds on work started in the following two commits:
commit 24ed6739b6
Date: Thu Jan 30 14:35:40 2020 +0000
gdb/remote: Restore support for 'S' stop reply packet
commit cada5fc921
Date: Wed Mar 11 12:30:13 2020 +0000
gdb: Handle W and X remote packets without giving a warning
This is related to how GDB handles remote targets that send back 'S'
packets.
In the first of the above commits we fixed GDB's ability to handle a
single process, single threaded target that sends back 'S' packets.
Although the 'T' packet would always be preferred to 'S' these days,
there's nothing really wrong with 'S' for this situation.
The second commit above fixed an oversight in the first commit, a
single-process, multi-threaded target can send back a process wide
event, for example the process exited event 'W' without including a
process-id, this also is fine as there is no ambiguity in this case.
In PR gdb/26819 we run into yet another problem with the above
commits. In this case we have a single process with two threads, GDB
hits a breakpoint in thread 2 and then performs a stepi:
(gdb) b main
Breakpoint 1 at 0x1212340830: file infinite_loop.S, line 10.
(gdb) c
Continuing.
Thread 2 hit Breakpoint 1, main () at infinite_loop.S:10
10 in infinite_loop.S
(gdb) set debug remote 1
(gdb) stepi
Sending packet: $vCont;s:2#24...Packet received: S05
../binutils-gdb/gdb/infrun.c:5807: internal-error: int finish_step_over(execution_control_state*): Assertion `ecs->event_thread->control.trap_expected' failed.
What happens in this case is that on the RISC-V target displaced
stepping is not supported, so when the stepi is issued GDB steps just
thread 2. As only a single thread was set running the target decides
that is can get away with sending back an 'S' packet without a
thread-id. GDB then associates the stop with thread 1 (the first
non-exited thread), but as thread 1 was not previously set executing
the assertion seen above triggers.
As an aside I am surprised that the target sends pack 'S' in this
situation. The target is happy to send back 'T' (including thread-id)
when multiple threads are set running, so (to me) it would seem easier
to just always use the 'T' packet when multiple threads are in use.
However, the target only uses 'T' when multiple threads are actually
executing, otherwise an 'S' packet it used.
Still, when looking at the above situation we can see that GDB should
be able to understand which thread the 'S' reply is referring too.
The problem is that is that in commit 24ed6739b6 (above) when a stop
reply comes in with no thread-id we look for the first non-exited
thread and select that as the thread the stop applies too.
What we should really do is select the first non-exited, resumed thread,
and associate the stop event with this thread. In the above example
both thread 1 and 2 are non-exited, but only thread 2 is resumed, so
this is what we should use.
There's a test for this issue included which works with stock
gdbserver by disabling use of the 'T' packet, and enabling
'scheduler-locking' within GDB so only one thread is set running.
gdb/ChangeLog:
PR gdb/26819
* remote.c
(remote_target::select_thread_for_ambiguous_stop_reply): New
member function.
(remote_target::process_stop_reply): Call
select_thread_for_ambiguous_stop_reply.
gdb/testsuite/ChangeLog:
PR gdb/26819
* gdb.server/stop-reply-no-thread-multi.c: New file.
* gdb.server/stop-reply-no-thread-multi.exp: New file.
Change-Id: I9b49d76c2a99063dcc76203fa0f5270a72825d15
The next patch moves the target commit_resume method to be a
process_stratum_target-only method. The only non-process targets that
currently implement the commit_resume method are the btrace and full
record targets. The only reason they need to do so is to prevent a
commit resume from reaching the beneath (process) target if they are
currently replaying.
This is important if a record target is used on top of the remote target
(the only process target implementing the commit_resume method).
Currently, the remote target checks the `thread_info::executing` flag of
a thread to know if it should commit resume that thread:
if (!tp->executing || remote_thr->vcont_resumed)
continue;
The `tp->executing` flag is set by infrun when it has asked the target
stack to resume the thread, and therefore if the thread is executing,
from its point of view. It _not_ equivalent to whether the remote
target was asked to resume this thread.
Indeed, if infrun asks the target stack to resume some thread while the
record target is replaying, the record target won't forward the resume
request the remote target beneath, because we don't actually want to
resume the thread on the execution target. But the `tp->executing` flag
is still set, because from the point of view of infrun, the thread
executes. So, if the commit_resume call wasn't intercepted by the
record target as it is today and did reach the remote target, the remote
target would say "Oh, this thread should be executing and I haven't
vCont-resumed it! I must vCont-resume it!". But that would be wrong,
because it was never asked to resume this thread, the resume request did
not reach it. This is why the record targets currently need to
implement commit_resume: to prevent the beneath target from
commit_resuming threads it wasn't asked to resume.
Since commit_resume will become a method on process_stratum_target in
the following patch, record targets won't have a chance to intercept the
calls and that would result in the remote target commit_resuming threads
it shouldn't. To avoid this, this patch makes the remote target track
its own thread resumption state. That means, tracking which threads it
was asked to resume via target_ops::resume. Regardless of the context
of this patch, I think this change makes it easier to understand how
resume / commit_resume works in the remote target. It makes the target
more self-contained, as it only depends on what it gets asked to do via
the target methods, and not on tp->executing, which is a flag maintained
from the point of view of infrun.
I initially made it so this state was only used when the remote target
operates in non-stop mode, since commit_resume is only used when the
target is non-stop. However, it's more consistent and it can be useful
to maintain this state even in all-stop too. In all-stop, receiving a
stop notification for one thread means all threads of the target are
considered stopped.
From the point of view of the remote target, there are three states a
thread can be in:
1. not resumed
2. resumed but pending vCont-resume
3. resumed
State 2 only exists when the target is non-stop.
As of this patch, valid state transitions are:
- 1 -> 2 (through the target resume method if in non-stop)
- 2 -> 3 (through the target commit_resume method if in non-stop)
- 1 -> 3 (through the target resume method if in all-stop)
- 3 -> 1 (through a remote stop notification / reporting an event to the
event loop)
A subsequent patch will make it possible to go from 2 to 1, in case
infrun asks to stop a thread that was resumed but not commit-resumed
yet. I don't think it can happen as of now.
In terms of code, this patch replaces the vcont_resumed field with an
enumeration that explicitly represents the three states described above.
The last_resume_sig and last_resume_step fields are moved to a structure
which is clearly identified as only used when the thread is in the
"resumed but pending vCont-resume" state.
gdb/ChangeLog:
* remote.c (enum class resume_state): New.
(struct resumed_pending_vcont_info): New.
(struct remote_thread_info) <resume_state, set_not_resumed,
set_resumed_pending_vcont, resumed_pending_vcont_info,
set_resumed, m_resume_state, m_resumed_pending_vcont_info>:
New.
<last_resume_step, last_resume_sig, vcont_resumed>: Remove.
(remote_target::remote_add_thread): Adjust.
(remote_target::process_initial_stop_replies): Adjust.
(remote_target::resume): Adjust.
(remote_target::commit_resume): Rely on state in
remote_thread_info and not on tp->executing.
(remote_target::process_stop_reply): Adjust.
Change-Id: I10480919ccb4552faa62575e447a36dbe7c2d523
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.
Because target_section_table only holds a vector, and because it is
used in an "open" way, this patch makes it just be an alias for the
std::vector specialization. This makes the code less wordy. If we do
ever want to add more specialized behavior to this type, it's simple
enough to convert it back to a struct with the few needed methods
implied by this change.
gdb/ChangeLog
2020-10-12 Tom Tromey <tom@tromey.com>
* target.h (struct target_ops) <get_section_table>: Update.
(target_get_section_table): Update.
* target.c (target_get_section_table, target_section_by_addr)
(memory_xfer_partial_1): Update.
* target-section.h (target_section_table): Now an alias.
* target-delegates.c: Rebuild.
* target-debug.h (target_debug_print_target_section_table_p):
Rename from target_debug_print_struct_target_section_table_p.
* symfile.c (build_section_addr_info_from_section_table): Update.
* solib.c (solib_map_sections, solib_contains_address_p): Update.
* solib-svr4.c (scan_dyntag): Update.
* solib-dsbt.c (scan_dyntag): Update.
* remote.c (remote_target::remote_xfer_live_readonly_partial):
Update.
* record-full.c (record_full_core_target::xfer_partial): Update.
* progspace.h (struct program_space) <target_sections>: Update.
* exec.h (print_section_info): Update.
* exec.c (exec_target::close, build_section_table)
(add_target_sections, add_target_sections_of_objfile)
(remove_target_sections, exec_on_vfork)
(section_table_available_memory)
(section_table_xfer_memory_partial)
(exec_target::get_section_table, exec_target::xfer_partial)
(print_section_info, set_section_command)
(exec_set_section_address, exec_target::has_memory): Update.
* corelow.c (core_target::build_file_mappings)
(core_target::xfer_partial, core_target::info_proc_mappings)
(core_target::info_proc_mappings): Update.
* bfd-target.c (class target_bfd): Update
This changes target_section_table to wrap a std::vector. This
simplifies some code, and also enables the simplifications coming in
the subsequent patches.
Note that for solib, I chose to have it use a pointer to a
target_section_table. This is more convoluted than would be ideal,
but I didn't want to convert solib to new/delete as a prerequisite for
this series.
gdb/ChangeLog
2020-10-12 Tom Tromey <tom@tromey.com>
* target.c (target_section_by_addr, memory_xfer_partial_1):
Update.
* target-section.h (struct target_section_table): Use
std::vector.
* symfile.h (build_section_addr_info_from_section_table): Take a
target_section_table.
* symfile.c (build_section_addr_info_from_section_table): Take a
target_section_table.
* solist.h (struct so_list) <sections>: Change type.
<sections_end>: Remove.
* solib.c (solib_map_sections, clear_so, solib_read_symbols)
(solib_contains_address_p): Update.
* solib-svr4.c (scan_dyntag): Update.
* solib-dsbt.c (scan_dyntag): Update.
* remote.c (remote_target::remote_xfer_live_readonly_partial):
Update.
* record-full.c (record_full_core_start, record_full_core_end):
Remove.
(record_full_core_sections): New global.
(record_full_core_open_1, record_full_core_target::xfer_partial):
Update.
* exec.h (build_section_table, section_table_xfer_memory_partial)
(add_target_sections): Take a target_section_table.
* exec.c (exec_file_attach, clear_section_table): Update.
(resize_section_table): Remove.
(build_section_table, add_target_sections): Take a
target_section_table.
(add_target_sections_of_objfile, remove_target_sections)
(exec_on_vfork): Update.
(section_table_available_memory): Take a target_section_table.
(section_table_read_available_memory): Update.
(section_table_xfer_memory_partial): Take a target_section_table.
(print_section_info, set_section_command)
(exec_set_section_address, exec_target::has_memory): Update.
* corelow.c (class core_target) <m_core_section_table,
m_core_file_mappings>: Remove braces.
<~core_target>: Remove.
(core_target::core_target): Update.
(core_target::~core_target): Remove.
(core_target::build_file_mappings)
(core_target::xfer_memory_via_mappings)
(core_target::xfer_partial, core_target::info_proc_mappings):
Update.
* bfd-target.c (target_bfd::xfer_partial): Update.
(target_bfd::target_bfd): Update.
(target_bfd::~target_bfd): Remove.
This moves the simple_search_memory function to a new file,
gdbsupport/search.cc. The API is slightly changed to make it more
general. This generality is useful for wiring it to gdbserver, and
also for unit testing.
gdb/ChangeLog
2020-10-07 Tom Tromey <tromey@adacore.com>
* target.h (simple_search_memory): Don't declare.
* target.c (simple_search_memory): Move to gdbsupport.
(default_search_memory): Update.
* remote.c (remote_target::search_memory): Update.
gdbsupport/ChangeLog
2020-10-07 Tom Tromey <tromey@adacore.com>
* Makefile.in: Rebuild.
* Makefile.am (libgdbsupport_a_SOURCES): Add search.cc.
* search.h: New file.
* search.cc: New file.
Assign names to async event/signal handlers. They will be used in debug
messages when file handlers are invoked.
Unlike in the previous patch, the names are not copied in the structure,
since we don't need to (all names are string literals for the moment).
gdb/ChangeLog:
* async-event.h (create_async_signal_handler): Add name
parameter.
(create_async_event_handler): Likewise.
* async-event.c (struct async_signal_handler) <name>: New field.
(struct async_event_handler) <name>: New field.
(create_async_signal_handler): Assign name.
(create_async_event_handler): Assign name.
* event-top.c (async_init_signals): Pass name when creating
handler.
* infrun.c (_initialize_infrun): Likewise.
* record-btrace.c (record_btrace_push_target): Likewise.
* record-full.c (record_full_open): Likewise.
* remote-notif.c (remote_notif_state_allocate): Likewise.
* remote.c (remote_target::open_1): Likewise.
* tui/tui-win.c (tui_initialize_win): Likewise.
Change-Id: Icd9d9f775542ae5fc2cd148c12f481e7885936d5
In non-stop mode, remote targets mark an async event source whose
callback is supposed to result in calling remote_target::wait_ns to
either process the event queue, or acknowledge an incoming %Stop
notification.
The callback in question is remote_async_inferior_event_handler, where
we call inferior_event_handler, to end up in fetch_inferior_event ->
target_wait -> remote_target::wait -> remote_target::wait_ns.
A problem here however is that when debugging multiple targets,
fetch_inferior_event can pull events out of any target picked at
random, for event fairness. This means that when
remote_async_inferior_event_handler returns, remote_target::wait may
have not been called at all, and thus pending notifications may have
not been acked. Because async event sources auto-clear, when
remote_async_inferior_event_handler returns the async event handler is
no longer marked, so the event loop won't automatically call
remote_async_inferior_event_handler again to try to process the
pending remote notifications/queue. The result is that stop events
may end up not processed, e.g., "interrupt -a" seemingly not managing
to stop all threads.
Fix this by making remote_async_inferior_event_handler mark the event
handler again before returning, if necessary.
Maybe a better fix would be to make async event handlers not
auto-clear themselves, make that the responsibility of the callback,
so that the event loop would keep calling the callback automatically.
Or, we could try making so that fetch_inferior_event would optionally
handle events only for the target that it got passed down via
parameter. However, I don't think now just before branching is the
time to try to do any such change.
gdb/ChangeLog:
PR gdb/26199
* remote.c (remote_target::open_1): Pass remote target pointer as
data to create_async_event_handler.
(remote_async_inferior_event_handler): Mark async event handler
before returning if the remote target still has either pending
events or unacknowledged notifications.
I noticed that fetch_inferior_event receives the client_data parameter
from its caller, inferior_event_handler, but doesn't actually need it.
This patch removes it. In turn, inferior_event_handler doesn't use its
parameter, so remove it too.
The `data` argument used when registering
remote_async_inferior_event_handler is changed to NULL, to avoid
confusion. It could make people think that the value passed is used
somewhere, when in fact it's not.
gdb/ChangeLog:
* inf-loop.c (inferior_event_handler): Remove client_data param.
* inf-loop.h (inferior_event_handler): Likewise.
* infcmd.c (step_1): Adjust.
* infrun.c (proceed): Adjust.
(fetch_inferior_event): Remove client_data param.
(infrun_async_inferior_event_handler): Adjust.
* infrun.h (fetch_inferior_event): Remove `void *` param.
* linux-nat.c (handle_target_event): Adjust.
* record-btrace.c (record_btrace_handle_async_inferior_event):
Adjust.
* record-full.c (record_full_async_inferior_event_handler):
Adjust.
* remote.c (remote_async_inferior_event_handler): Adjust.
Change-Id: I3c2aa1eb0ea3e0985df096660d2dcd794674f2ea
Currently, a user can define an alias, but cannot have default
arguments for this alias.
This patch modifies the 'alias' command so that default args can
be provided.
(gdb) h alias
Define a new command that is an alias of an existing command.
Usage: alias [-a] [--] ALIAS = COMMAND [DEFAULT-ARGS...]
ALIAS is the name of the alias command to create.
COMMAND is the command being aliased to.
Options:
-a
Specify that ALIAS is an abbreviation of COMMAND.
Abbreviations are not used in command completion..
GDB will automatically prepend the provided DEFAULT-ARGS to the list
of arguments explicitly provided when using ALIAS.
Use "help aliases" to list all user defined aliases and their default args.
Examples:
Make "spe" an alias of "set print elements":
alias spe set print elements
Make "elms" an alias of "elements" in the "set print" command:
alias -a set print elms set print elements
Make "btf" an alias of "backtrace -full -past-entry -past-main" :
alias btf = backtrace -full -past-entry -past-main
Make "wLapPeu" an alias of 2 nested "with":
alias wLapPeu = with language pascal -- with print elements unlimited --
(gdb)
The way 'default-args' is implemented makes it trivial to set default
args also for GDB commands (such as "backtrace") and for GDB pre-defined
aliases (such as "bt"). It was however deemed better to not allow to
define default arguments for pre-defined commands and aliases, to avoid
users believing that e.g. default args for "backtrace" would apply to "bt".
If needed, default-args could be allowed for GDB predefined commands
and aliases by adding a command
'set default-args GDB_COMMAND_OR_PREDEFINED_ALIAS [DEFAULT-ARGS...]'.
* 'alias' command now has a completer that helps to complete:
- ALIAS (if the user defines an alias after a prefix),
- the aliased COMMAND
- the possible options for the aliased COMMAND.
* Help and apropos commands show the definitions of the aliases
that have default arguments, e.g.
(gdb) help backtrace
backtrace, btf, where, bt
alias btf = backtrace -full -past-entry -past-main
Print backtrace of all stack frames, or innermost COUNT frames.
Usage: backtrace [OPTION]... [QUALIFIER]... [COUNT | -COUNT]
Options:
-entry-values no|only|preferred|if-needed|both|compact|default
Set printing of function arguments at function entry.
...
gdb/ChangeLog
2020-06-22 Philippe Waroquiers <philippe.waroquiers@skynet.be>
* cli/cli-cmds.c (lookup_cmd_for_default_args)
(alias_command_completer)
(make_alias_options_def_group): New functions.
(alias_opts, alias_option_defs): New struct and array.
(alias_usage_error): Update usage.
(alias_command): Handles optional DEFAULT-ARGS... arguments.
Use option framework.
(_initialize_cli_cmds): Update alias command help.
Update aliases command help.
(show_user):
Add NULL for new default_args lookup_cmd argument.
(valid_command_p): Rename to validate_aliased_command.
Add NULL for new default_args lookup_cmd argument. Verify that the
aliased_command has no default args.
* cli/cli-decode.c (help_cmd): Show aliases definitions.
(lookup_cmd_1, lookup_cmd): New argument default_args.
(add_alias_cmd):
Add NULL for new default_args lookup_cmd argument.
(print_help_for_command): Show default args under the layout
alias some_alias = some_aliased_cmd some_alias_default_arg.
* cli/cli-decode.h (struct cmd_list_element): New member default_args.
xfree default_args in destructor.
* cli/cli-script.c (process_next_line, do_define_command):
Add NULL for new default_args lookup_cmd argument.
* command.h: Declare new default_args argument in lookup_cmd
and lookup_cmd_1.
* completer.c (complete_line_internal_1):
Add NULL for new default_args lookup_cmd or lookup_cmd_1 argument.
* guile/scm-cmd.c (gdbscm_parse_command_name): Likewise.
* guile/scm-param.c (add_setshow_generic, pascm_parameter_defined_p):
Likewise.
* infcmd.c (_initialize_infcmd): Likewise.
* python/py-auto-load.c (gdbpy_initialize_auto_load): Likewise.
* python/py-cmd.c (gdbpy_parse_command_name): Likewise.
* python/py-param.c (add_setshow_generic): Likewise.
* remote.c (_initialize_remote): Likewise.
* top.c (execute_command): Prepend default_args if command has some.
(set_verbose):
Add NULL for new default_args lookup_cmd or lookup_cmd_1 argument.
* tracepoint.c (validate_actionline, encode_actions_1):
Add NULL for new default_args lookup_cmd or lookup_cmd_1 argument.
gdb/ChangeLog:
2020-06-18 Pedro Alves <palves@redhat.com>
* remote.c (remote_target::remote_notice_new_inferior): Use
switch_to_thread instead of writing to inferior_ptid directly.
(remote_target::add_current_inferior_and_thread): Use
switch_to_no_thread instead of writing to inferior_ptid directly.
(extended_remote_target::attach): Use switch_to_inferior_no_thread
and switch_to_thread instead of using set_current_inferior or
writing to inferior_ptid directly.
I was inspired by a series of patches merged by Alan Modra in the other
projects, so I did the same in GDB with a bit of Coccinelle and grep.
This patch removes the unnecessary NULL checks before calls to xfree.
They are unnecessary because xfree already does a NULL check. Since
free is supposed to handle NULL values correctly, the NULL check in
xfree itself is also questionable, but I've left it there for now.
gdb/ChangeLog:
* coffread.c (patch_type): Remove NULL check before xfree.
* corefile.c (set_gnutarget): Likewise.
* cp-abi.c (set_cp_abi_as_auto_default): Likewise.
* exec.c (build_section_table): Likewise.
* remote.c (remote_target::pass_signals): Likewise.
* utils.c (n_spaces): Likewise.
* cli/cli-script.c (document_command): Likewise.
* i386-windows-tdep.c (core_process_module_section): Likewise.
* linux-fork.c (struct fork_info) <~fork_info>: Likewise.
Instead of maintaining two vectors, I added a small `segment` class
which holds both the base address and size of one segment and replaced
the two `segment_bases` and `segment_sizes` arrays with a single vector.
The rest of the changes are straightforward, no behavior changes are
expected.
gdb/ChangeLog:
* symfile.h (struct symfile_segment_data) <struct segment>: New.
<segments>: New.
<segment_bases, segment_sizes>: Remove.
* symfile.c (default_symfile_segments): Update.
* elfread.c (elf_symfile_segments): Update.
* remote.c (remote_target::get_offsets): Update.
* solib-target.c (solib_target_relocate_section_addresses):
Update.
- Allocate this structure with new instead of XNEW, use a unique pointer
to manage its lifetime.
- Change a few functions to return a unique pointer instead of a
plain pointer.
- Change free_symfile_segment_data to be symfile_segment_data's
destructor.
gdb/ChangeLog:
* symfile.h (struct symfile_segment_data): Initialize fields.
<~symfile_segment_data>: Add.
(symfile_segment_data_up): New.
(struct sym_fns) <sym_segments>: Return a
symfile_segment_data_up.
(default_symfile_segments): Return a symfile_segment_data_up.
(free_symfile_segment_data): Remove.
(get_symfile_segment_data): Return a symfile_segment_data_up.
* symfile.c (default_symfile_segments): Likewise.
(get_symfile_segment_data): Likewise.
(free_symfile_segment_data): Remove.
(symfile_find_segment_sections): Update.
* elfread.c (elf_symfile_segments): Return a
symfile_segment_data_up.
* remote.c (remote_target::get_offsets): Update.
* solib-target.c (solib_target_relocate_section_addresses):
Update.
* symfile-debug.c (debug_sym_segments): Return a
symfile_segment_data_up.
The next commit updates command-def-selftests.c to detect missing
or wrong prefix commands in a list of subcommands.
This command structure selftest detects a series of problems
that are fixed by this commit.
Many commands have a null prefix command, e.g.
(gdb) maintenance selftest command_str
Running selftest command_structure_invariants.
list 0x560417949cb8 reachable via prefix 'append binary '. command 'memory' has null prefixcmd
list 0x560417949cb8 reachable via prefix 'append binary '. command 'value' has null prefixcmd
...
Most of these are fixed by the following changes:
* do_add_cmd searches the prefix command having the list
in which the command is added.
This ensures that a command defined after its prefix command
gets the correct prefix command.
* Due to the GDB initialization order, a GDB file can define
a subcommand before the prefix command is defined.
So, have add_prefix_cmd calling a new recursive function
'update_prefix_field_of_prefix_commands' to set the prefix
command of all sub-commands that are now reachable from
this newly defined prefix command. Note that this recursive
call replaces the function 'set_prefix_cmd' that was providing
a partial solution to this problem.
Following that, 2 python commands (defined after all the other GDB
commands) got a wrong prefix command, e.g. "info frame-filter" has
as prefix command the "i" alias of "info". This is fixed by having
lookup_cmd_for_prefixlist returning the aliased command rather than
the alias.
After that, one remaining problem:
(gdb) maintenance selftest command_str
Running selftest command_structure_invariants.
list 0x55f320272298 reachable via prefix 'set remote '. command 'system-call-allowed' has null prefixcmd
Self test failed: self-test failed at ../../classfix/gdb/unittests/command-def-selftests.c:196
Ran 1 unit tests, 1 failed
(gdb)
Caused by initialize_remote_fileio that was taking the address of
its arguments remote_set_cmdlist and remote_show_cmdlist instead
of receiving the correct values to use as list.
2020-05-15 Philippe Waroquiers <philippe.waroquiers@skynet.be>
* cli/cli-decode.c (lookup_cmd_for_prefix): Return the aliased command
as prefix, not one of its aliases.
(set_cmd_prefix): Remove.
(do_add_cmd): Centralize the setting of the prefix of a command, when
command is defined after its full chain of prefix commands.
(add_alias_cmd): Remove call to set_cmd_prefix, as do_add_cmd does it.
(add_setshow_cmd_full): Likewise.
(update_prefix_field_of_prefixed_commands): New function.
(add_prefix_cmd): Replace non working call to set_cmd_prefix by
update_prefix_field_of_prefixed_commands.
* gdb/remote-fileio.c (initialize_remote_fileio): Use the real
addresses of remote_set_cmdlist and remote_show_cmdlist given
as argument, not the address of an argument.
* gdb/remote-fileio.h (initialize_remote_fileio): Likewise.
* gdb/remote.c (_initialize_remote): Likewise.
In stop_all_threads, GDB sends signals to other threads in an attempt
to stop them. While in a typical scenario the expected wait status is
TARGET_WAITKIND_STOPPED, it is possible that the thread GDB attempted
to stop has already terminated. If so, a waitstatus other than
TARGET_WAITKIND_STOPPED would be received. Handle this case
appropriately.
If a wait status that denotes thread termination is ignored, GDB goes
into an infinite loop in stop_all_threads.
E.g.:
$ gdb ./a.out
(gdb) start
...
(gdb) add-inferior -exec ./a.out
...
(gdb) inferior 2
...
(gdb) start
...
(gdb) set schedule-multiple on
(gdb) set debug infrun 2
(gdb) continue
Continuing.
infrun: clear_proceed_status_thread (process 10449)
infrun: clear_proceed_status_thread (process 10453)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: proceed: resuming process 10449
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 10449] at 0x55555555514e
infrun: infrun_async(1)
infrun: prepare_to_wait
infrun: proceed: resuming process 10453
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 10453] at 0x55555555514e
infrun: prepare_to_wait
infrun: Found 2 inferiors, starting at #0
infrun: target_wait (-1.0.0, status) =
infrun: 10449.10449.0 [process 10449],
infrun: status->kind = exited, status = 0
infrun: handle_inferior_event status->kind = exited, status = 0
[Inferior 1 (process 10449) exited normally]
infrun: stop_waiting
infrun: stop_all_threads
infrun: stop_all_threads, pass=0, iterations=0
infrun: process 10453 executing, need stop
infrun: target_wait (-1.0.0, status) =
infrun: 10453.10453.0 [process 10453],
infrun: status->kind = exited, status = 0
infrun: stop_all_threads status->kind = exited, status = 0 process 10453
infrun: process 10453 executing, already stopping
infrun: target_wait (-1.0.0, status) =
infrun: -1.0.0 [process -1],
infrun: status->kind = no-resumed
infrun: infrun_async(0)
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
infrun: stop_all_threads status->kind = no-resumed process -1
infrun: process 10453 executing, already stopping
...
And this polling goes on forever. This patch prevents the infinite
looping behavior. For the same scenario above, we obtain the
following behavior:
...
(gdb) continue
Continuing.
infrun: clear_proceed_status_thread (process 31229)
infrun: clear_proceed_status_thread (process 31233)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: proceed: resuming process 31229
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 31229] at 0x55555555514e
infrun: infrun_async(1)
infrun: prepare_to_wait
infrun: proceed: resuming process 31233
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 31233] at 0x55555555514e
infrun: prepare_to_wait
infrun: Found 2 inferiors, starting at #0
infrun: target_wait (-1.0.0, status) =
infrun: 31229.31229.0 [process 31229],
infrun: status->kind = exited, status = 0
infrun: handle_inferior_event status->kind = exited, status = 0
[Inferior 1 (process 31229) exited normally]
infrun: stop_waiting
infrun: stop_all_threads
infrun: stop_all_threads, pass=0, iterations=0
infrun: process 31233 executing, need stop
infrun: target_wait (-1.0.0, status) =
infrun: 31233.31233.0 [process 31233],
infrun: status->kind = exited, status = 0
infrun: stop_all_threads status->kind = exited, status = 0 process 31233
infrun: saving status status->kind = exited, status = 0 for 31233.31233.0
infrun: process 31233 not executing
infrun: stop_all_threads, pass=1, iterations=1
infrun: process 31233 not executing
infrun: stop_all_threads done
(gdb)
The exit event from Inferior 1 is received and shown to the user.
The exit event from Inferior 2 is not displayed, but kept pending.
(gdb) info inferiors
Num Description Connection Executable
* 1 <null> a.out
2 process 31233 1 (native) a.out
(gdb) inferior 2
[Switching to inferior 2 [process 31233] (a.out)]
[Switching to thread 2.1 (process 31233)]
Couldn't get registers: No such process.
(gdb) continue
Continuing.
infrun: clear_proceed_status_thread (process 31233)
infrun: clear_proceed_status_thread: thread process 31233 has pending wait status status->kind = exited, status = 0 (currently_stepping=0).
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: proceed: resuming process 31233
infrun: resume: thread process 31233 has pending wait status status->kind = exited, status = 0 (currently_stepping=0).
infrun: prepare_to_wait
infrun: Using pending wait status status->kind = exited, status = 0 for process 31233.
infrun: target_wait (-1.0.0, status) =
infrun: 31233.31233.0 [process 31233],
infrun: status->kind = exited, status = 0
infrun: handle_inferior_event status->kind = exited, status = 0
[Inferior 2 (process 31233) exited normally]
infrun: stop_waiting
(gdb) info inferiors
Num Description Connection Executable
1 <null> a.out
* 2 <null> a.out
(gdb)
When a process exits and we leave the process exit event pending, we
need to make sure that at least one thread is left listed in the
inferior's thread list. This is necessary in order to make sure we
have a thread that we can later resume, so the process exit event can
be collected/reported.
When native debugging, the GNU/Linux back end already makes sure that
the last LWP isn't deleted.
When remote debugging against GNU/Linux GDBserver, the GNU/Linux
GDBserver backend also makes sure that the last thread isn't deleted
until the process exit event is reported to GDBserver core.
However, between the backend reporting the process exit event to
GDBserver core, and GDB consuming the event, GDB may update the thread
list and find no thread left in the process. The process exit event
will be pending somewhere in GDBserver's stop reply queue, or
gdb/remote.c's queue, or whathever other event queue inbetween
GDBserver and infrun.c's handle_inferior_event.
This patch tweaks remote.c's target_update_thread_list implementation
to avoid deleting the last thread of an inferior.
In the past, this case of inferior-with-no-threads led to a special
case at the bottom of handle_no_resumed, where it reads:
/* Note however that we may find no resumed thread because the whole
process exited meanwhile (thus updating the thread list results
in an empty thread list). In this case we know we'll be getting
a process exit event shortly. */
for (inferior *inf : all_non_exited_inferiors (ecs->target))
In current master, that code path is still reachable with the
gdb.threads/continue-pending-after-query.exp testcase, when tested
against GDBserver, with "maint set target-non-stop" forced "on".
With this patch, the scenario that loop was concerned about is still
properly handled, because the loop above it finds the process's last
thread with "executing" set to true, and thus the handle_no_resumed
function still returns true.
Since GNU/Linux native and remote are the only targets that support
non-stop mode, and with this patch, we always make sure the inferior
has at least one thread, this patch also removes that "inferior with
no threads" special case handling from handle_no_resumed.
Since remote.c now has a special case where we treat a thread that has
already exited as if it was still alive, we might need to tweak
remote.c's target_thread_alive implementation to return true for that
thread without querying the remote side (which would say "no, not
alive"). After inspecting all the target_thread_alive calls in the
codebase, it seems that only the one from prune_threads could result
in that thread being accidentally deleted. There's only one call to
prune_threads in GDB's common code, so this patch handles this by
replacing the prune_threads call with a delete_exited_threads call.
This seems like an improvement anyway, because we'll still be doing
what the comment suggests we want to do, and, we avoid remote protocol
traffic.
Regression-tested on X86_64 Linux.
gdb/ChangeLog:
2020-05-14 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Tom de Vries <tdevries@suse.de>
Pedro Alves <palves@redhat.com>
PR threads/25478
* infrun.c (stop_all_threads): Do NOT ignore
TARGET_WAITKIND_NO_RESUMED, TARGET_WAITKIND_THREAD_EXITED,
TARGET_WAITKIND_EXITED, TARGET_WAITKIND_SIGNALLED wait statuses
received.
(handle_no_resumed): Remove code handling a live inferior with no
threads.
* remote.c (has_single_non_exited_thread): New.
(remote_target::update_thread_list): Do not delete a thread if is
the last thread of the process.
* thread.c (thread_select): Call delete_exited_threads instead of
prune_threads.
gdb/testsuite/ChangeLog:
2020-05-14 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Pedro Alves <palves@redhat.com>
* gdb.multi/multi-exit.c: New file.
* gdb.multi/multi-exit.exp: New file.
* gdb.multi/multi-kill.c: New file.
* gdb.multi/multi-kill.exp: New file.
Currently there are many prefix commands that do nothing but call
either help_list or cmd_show_list. I happened to notice that one such
call, for "set print type", used the wrong command list parameter,
causing incorrect output.
Rather than fix this bug in isolation, I decided to eliminate this
possibility by adding two new ways to add prefix commands, which
simply route the call to help_list or cmd_show_list, as appropriate.
This makes it impossible for a mismatch to occur.
In some cases, a bit of output was removed; however, I don't think
this output in general was very useful. It seemed redundant with
what's already printed by help_list. A representative example is this
hunk, removed from ada-lang.c:
- printf_unfiltered (_(\
-"\"set ada\" must be followed by the name of a setting.\n"));
This simplified the CLI style set/show commands quite a bit, and
allowed the deletion of a macro.
This also cleans up some unusual code in windows-tdep.c.
Tested on x86-64 Fedora 30. Note that I have no way to build the
go32-nat.c change.
gdb/ChangeLog
2020-04-17 Tom Tromey <tromey@adacore.com>
* auto-load.c (show_auto_load_cmd): Remove.
(auto_load_show_cmdlist_get): Use add_show_prefix_cmd.
* arc-tdep.c (_initialize_arc_tdep): Use add_show_prefix_cmd.
(maintenance_print_arc_command): Remove.
* tui/tui-win.c (tui_command): Remove.
(tui_get_cmd_list): Use add_basic_prefix_cmd.
* tui/tui-layout.c (tui_layout_command): Remove.
(_initialize_tui_layout): Use add_basic_prefix_cmd.
* python/python.c (user_set_python, user_show_python): Remove.
(_initialize_python): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* guile/guile.c (set_guile_command, show_guile_command): Remove.
(install_gdb_commands): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
(info_guile_command): Remove.
* dwarf2/read.c (set_dwarf_cmd, show_dwarf_cmd): Remove.
(_initialize_dwarf2_read): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* cli/cli-style.h (class cli_style_option) <add_setshow_commands>:
Remove do_set and do_show parameters.
* cli/cli-style.c (set_style, show_style): Remove.
(_initialize_cli_style): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
(cli_style_option::add_setshow_commands): Remove do_set and
do_show parameters.
(cli_style_option::add_setshow_commands): Use
add_basic_prefix_cmd, add_show_prefix_cmd.
(STYLE_ADD_SETSHOW_COMMANDS): Remove macro.
(set_style_name): Remove.
* cli/cli-dump.c (dump_command, append_command): Remove.
(srec_dump_command, ihex_dump_command, verilog_dump_command)
(tekhex_dump_command, binary_dump_command)
(binary_append_command): Remove.
(_initialize_cli_dump): Use add_basic_prefix_cmd.
* windows-tdep.c (w32_prefix_command_valid): Remove global.
(init_w32_command_list): Remove; move into ...
(_initialize_windows_tdep): ... here. Use add_basic_prefix_cmd.
* valprint.c (set_print, show_print, set_print_raw)
(show_print_raw): Remove.
(_initialize_valprint): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* typeprint.c (set_print_type, show_print_type): Remove.
(_initialize_typeprint): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* record.c (set_record_command, show_record_command): Remove.
(_initialize_record): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* cli/cli-cmds.c (_initialize_cli_cmds): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
(info_command, show_command, set_debug, show_debug): Remove.
* top.h (set_history, show_history): Don't declare.
* top.c (set_history, show_history): Remove.
* target-descriptions.c (set_tdesc_cmd, show_tdesc_cmd)
(unset_tdesc_cmd): Remove.
(_initialize_target_descriptions): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* symtab.c (info_module_command): Remove.
(_initialize_symtab): Use add_basic_prefix_cmd.
* symfile.c (overlay_command): Remove.
(_initialize_symfile): Use add_basic_prefix_cmd.
* sparc64-tdep.c (info_adi_command): Remove.
(_initialize_sparc64_adi_tdep): Use add_basic_prefix_cmd.
* sh-tdep.c (show_sh_command, set_sh_command): Remove.
(_initialize_sh_tdep): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* serial.c (serial_set_cmd, serial_show_cmd): Remove.
(_initialize_serial): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* ser-tcp.c (set_tcp_cmd, show_tcp_cmd): Remove.
(_initialize_ser_tcp): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* rs6000-tdep.c (set_powerpc_command, show_powerpc_command)
(_initialize_rs6000_tdep): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* riscv-tdep.c (show_riscv_command, set_riscv_command)
(show_debug_riscv_command, set_debug_riscv_command): Remove.
(_initialize_riscv_tdep): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* remote.c (remote_command, set_remote_cmd): Remove.
(_initialize_remote): Use add_basic_prefix_cmd.
* record-full.c (set_record_full_command)
(show_record_full_command): Remove.
(_initialize_record_full): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* record-btrace.c (cmd_set_record_btrace)
(cmd_show_record_btrace, cmd_set_record_btrace_bts)
(cmd_show_record_btrace_bts, cmd_set_record_btrace_pt)
(cmd_show_record_btrace_pt): Remove.
(_initialize_record_btrace): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* ravenscar-thread.c (set_ravenscar_command)
(show_ravenscar_command): Remove.
(_initialize_ravenscar): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* mips-tdep.c (show_mips_command, set_mips_command)
(_initialize_mips_tdep): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* maint.c (maintenance_command, maintenance_info_command)
(maintenance_check_command, maintenance_print_command)
(maintenance_set_cmd, maintenance_show_cmd): Remove.
(_initialize_maint_cmds): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
(show_per_command_cmd): Remove.
* maint-test-settings.c (maintenance_set_test_settings_cmd):
Remove.
(maintenance_show_test_settings_cmd): Remove.
(_initialize_maint_test_settings): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* maint-test-options.c (maintenance_test_options_command):
Remove.
(_initialize_maint_test_options): Use add_basic_prefix_cmd.
* macrocmd.c (macro_command): Remove
(_initialize_macrocmd): Use add_basic_prefix_cmd.
* language.c (set_check, show_check): Remove.
(_initialize_language): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* infcmd.c (unset_command): Remove.
(_initialize_infcmd): Use add_basic_prefix_cmd.
* i386-tdep.c (set_mpx_cmd, show_mpx_cmd): Remove.
(_initialize_i386_tdep): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* go32-nat.c (go32_info_dos_command): Remove.
(_initialize_go32_nat): Use add_basic_prefix_cmd.
* cli/cli-decode.c (do_prefix_cmd, add_basic_prefix_cmd)
(do_show_prefix_cmd, add_show_prefix_cmd): New functions.
* frame.c (set_backtrace_cmd, show_backtrace_cmd): Remove.
(_initialize_frame): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* dcache.c (set_dcache_command, show_dcache_command): Remove.
(_initialize_dcache): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* cp-support.c (maint_cplus_command): Remove.
(_initialize_cp_support): Use add_basic_prefix_cmd.
* btrace.c (maint_btrace_cmd, maint_btrace_set_cmd)
(maint_btrace_show_cmd, maint_btrace_pt_set_cmd)
(maint_btrace_pt_show_cmd, _initialize_btrace): Use
add_basic_prefix_cmd, add_show_prefix_cmd.
* breakpoint.c (save_command): Remove.
(_initialize_breakpoint): Use add_basic_prefix_cmd.
* arm-tdep.c (set_arm_command, show_arm_command): Remove.
(_initialize_arm_tdep): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* ada-lang.c (maint_set_ada_cmd, maint_show_ada_cmd)
(set_ada_command, show_ada_command): Remove.
(_initialize_ada_language): Use add_basic_prefix_cmd,
add_show_prefix_cmd.
* command.h (add_basic_prefix_cmd, add_show_prefix_cmd): Declare.
gdb/testsuite/ChangeLog
2020-04-17 Tom Tromey <tromey@adacore.com>
* gdb.cp/maint.exp (test_help): Simplify multiple_help_body.
Update tests.
* gdb.btrace/cpu.exp: Update tests.
* gdb.base/maint.exp: Update tests.
* gdb.base/default.exp: Update tests.
* gdb.base/completion.exp: Update tests.
This patch splits out some gdb-specific code from event-loop, into new
files async-event.[ch]. Strictly speaking this code could perhaps be
put into gdbsupport/, but because gdbserver does not currently use it,
it seemed better, for size reasons, to split it out.
gdb/ChangeLog
2020-04-13 Tom Tromey <tom@tromey.com>
* tui/tui-win.c: Include async-event.h.
* remote.c: Include async-event.h.
* remote-notif.c: Include async-event.h.
* record-full.c: Include async-event.h.
* record-btrace.c: Include async-event.h.
* infrun.c: Include async-event.h.
* event-top.c: Include async-event.h.
* event-loop.h: Move some declarations to async-event.h.
* event-loop.c: Don't include ser-event.h or top.h. Move some
code to async-event.c.
* async-event.h: New file.
* async-event.c: New file.
* Makefile.in (COMMON_SFILES): Add async-event.c.
(HFILES_NO_SRCDIR): Add async-event.h.
A gdbserver does not report a ptid in a 'W' or 'X' packet if multi-process
extensions are not supported or turned off. See
https://sourceware.org/gdb/current/onlinedocs/gdb/General-Query-Packets.html#multiprocess-extensionshttps://sourceware.org/gdb/current/onlinedocs/gdb/Stop-Reply-Packets.html#Stop-Reply-Packets
GDB's remote packet parser checks for whether a stop-reply packet
contains a ptid if the target is non-stop, and issues an error if no
ptid is included:
if (target_is_non_stop_p () && event->ptid == null_ptid)
error (_("No process or thread specified in stop reply: %s"), buf);
This leads to the following error when the non-stop
mode is turned on but multi-process extensions are off:
$ gdb
(gdb) set non-stop on
(gdb) set remote multiprocess-feature-packet off
(gdb) target remote | gdbserver - ./foo
Remote debugging using | gdbserver - ./foo
stdin/stdout redirected
Process ./foo created; pid = 3712
...
(gdb) continue
Continuing.
...
No process or thread specified in stop reply: W2a
(gdb)
Because the check is done for stop reply packets in general, a similar
situation occurs if the 'T' or 'Tthread' packet is disabled in
gdbserver (i.e. via --disable-packet=T). E.g:
$ gdb
(gdb) set non-stop on
(gdb) target remote | gdbserver --disable-packet=Tthread - ./foo
...
No process or thread specified in stop reply: T0506:0000000000000000;07:10e2ffffff7f0000;10:9060ddf7ff7f0000;
or
$ gdb
(gdb) set non-stop on
(gdb) target remote | gdbserver --disable-packet=T - ./foo
...
No process or thread specified in stop reply: S05
The commit
commit cada5fc921
Date: Wed Mar 11 12:30:13 2020 +0000
gdb: Handle W and X remote packets without giving a warning
and its predecessor
commit 24ed6739b6
Date: Thu Jan 30 14:35:40 2020 +0000
gdb/remote: Restore support for 'S' stop reply packet
added warnings for when GDB has to make a guess for a missing ptid in
case of multiple threads/inferiors. These warnings should suffice.
So, the simple solution is to remove the check completely.
Regression-tested on X86_64 Linux.
gdb/ChangeLog:
2020-04-01 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* remote.c (remote_target::remote_parse_stop_reply): Remove the
check for no ptid in the stop reply when the target is non-stop.
gdb/testsuite/ChangeLog:
2020-04-01 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* gdb.server/stop-reply-no-thread.exp: Enhance the test
scenario to cover execution until the end and also the case
when no packet is disabled when starting gdbserver.
In this commit:
commit 24ed6739b6
Date: Thu Jan 30 14:35:40 2020 +0000
gdb/remote: Restore support for 'S' stop reply packet
A regression was introduced such that the W and X packets would give a
warning in some cases. The warning was:
warning: multi-threaded target stopped without sending a thread-id, using first non-exited thread
This problem would arise when:
1. The multi-process extensions to the remote protocol were not
being used, and
2. The inferior has multiple threads.
In this case when the W (or X) packet arrives the ptid of the
stop_reply is set to null_ptid, then when we arrive in
process_stop_reply GDB spots that we have multiple non-exited theads,
but the stop event didn't specify a thread-id.
The problem with this is that the W (and X) packets are actually
process wide events, they apply to all threads. So not specifying a
thread-id is not a problem, in fact, the best these packets allow is
for the remote to specify a process-id, not a thread-id.
If we look at how the W (and X) packets deal with a specified
process-id, then what happens is GDB sets to stop_reply ptid to a
value which indicates all threads in the process, this is done by
creating a value `ptid_t (pid)`, which sets the pid field of the
ptid_t, but leaves the tid field as 0, indicating all threads.
So, this commit does the same thing for the case where there is not
process-id specified. In process_stop_reply we not distinguish
between stop events that apply to all threads, and those that apply to
only one. If the stop event applies to only one thread then we treat
it as before. If, however, the stop event applies to all threads,
then we find the first non-exited thread, and use the pid from this
thread to create a `ptid_t (pid)` value.
If the target has multiple inferiors, and receives a process wide
event without specifying a process-id GDB now gives this warning:
warning: multi-inferior target stopped without sending a process-id, using first non-exited inferior
gdb/ChangeLog:
* remote.c (remote_target::process_stop_reply): Handle events for
all threads differently.
gdb/testsuite/ChangeLog:
* gdb.server/exit-multiple-threads.c: New file.
* gdb.server/exit-multiple-threads.exp: New file.
A few spots in gdb use sprintf_vma to print a CORE_ADDR. This will
fail on a 32-bit build once CORE_ADDR is always a 64-bit type.
This patch replaces these calls with phex instead.
gdb/ChangeLog
2020-03-12 Tom Tromey <tom@tromey.com>
* remote.c (remote_target::download_tracepoint)
(remote_target::enable_tracepoint)
(remote_target::disable_tracepoint): Use phex, not sprintf_vma.
* breakpoint.c (print_recreate_masked_watchpoint): Use phex, not
sprintf_vma.
With this commit:
commit 5b6d1e4fa4
Date: Fri Jan 10 20:06:08 2020 +0000
Multi-target support
There was a regression in GDB's support for older aspects of the
remote protocol. Specifically, when a target sends the 'S' stop reply
packet (which doesn't include a thread-id) then GDB has to figure out
which thread actually stopped.
Before the above commit GDB figured this out by using inferior_ptid in
process_stop_reply, which contained the ptid of the current
process/thread. This would be fine for single threaded
targets (which is the only place using an S packet makes sense), but
in the general case, relying on inferior_ptid for processing a stop is
wrong - there's no reason to believe that what was GDB's current
thread will be the same thread that just stopped in the target.
With the above commit the inferior_ptid now has the value null_ptid
inside process_stop_reply, this can be seen in do_target_wait, where
we call switch_to_inferior_no_thread before calling do_target_wait_1.
The problem this causes can be seen in the new test that runs
gdbserver using the flag --disable-packet=T, and causes GDB to throw
this assertion:
inferior.c:279: internal-error: inferior* find_inferior_pid(process_stratum_target*, int): Assertion `pid != 0' failed.
A similar problem was fixed in this commit:
commit 3cada74087
Date: Thu Jan 11 00:23:04 2018 +0000
Fix backwards compatibility with old GDBservers (PR remote/22597)
However, this commit deals with the case where the T packet doesn't
include a thread-id, not the S packet case. This commit solves the
problem providing a thread-id at the GDB side if the remote target
doesn't provide one. The thread-id provided comes from
remote_state::general_thread, however, though this does work, I don't
think it is the ideal solution.
The remote_state tracks two threads, the continue_thread and the
general_thread, these are updated when GDB asks the remote target to
switch threads. The general_thread is set before performing things
like register or memory accesses, and the continue_thread is set
before things like continue or step commands. Further, the
general_thread is updated after a target stops to reference the thread
that stopped.
The first thing to note from the above description is that we have a
cycle of dependency, when a T packet arrives without a thread-id we
fill in the thread-id from the general_thread data. The thread-id
from the stop event is then used to set the general_thread. This in
itself feels a little weird.
The second question is why use the general_thread at all? You'd think
given how they are originally set that the continue thread would be a
better choice. The problem with this is that the continue_thread, if
the user just does "continue", will be set to the minus_one_ptid, in
the remote protocol this means all threads. When the stop arrives
with no thread-id and we use continue_thread we end up with a very
similar assertion to before because we now end up trying to lookup a
thread using the minus_one_ptid. By contrast, once GDB has connected
to a remote target the general_thread will be set to a valid
thread-id, after which, if the target is single threaded, and stop
events arrive without a thread-id, everything works fine.
There is one slight weirdness with the above behaviour though. When
GDB first connects to the remote target inferior_ptid is null_ptid,
however, upon connecting we query the remote for its threads. As the
thread information arrives GDB adds the threads to its internal
database, and this process involves setting inferior_ptid to the id of
each new thread in turn. Once we know about all the threads we wait
for a stop event from the remote target to indicate that GDB is now in
control of the target.
The problem is that after adding the new threads we don't reset
inferior_ptid, and the code path we use to wait for a stop event from
the target also doesn't reset inferior_ptid, so it turns out that
during the initial connection inferior_ptid is not null_ptid. This is
lucky, because during the initial connection the general_thread
variable _is_ set to null_ptid.
So, during the initial connection, if the first stop event is missing
a thread-id then we "provide" a thead-id from general_thread. This
turns out to be null_ptid meaning no thread-id is known, and then
during process_stop_reply we fill in the missing thread-id using
inferior_ptid.
This was all discussed on the mailing list here:
https://sourceware.org/ml/gdb-patches/2020-02/msg01011.html
My proposal for a fix then is:
1. Move the call to switch_to_inferior_no_thread into
do_target_wait_1, this means that in all cases where we are waiting
for an inferior the inferior_ptid will be set to null_ptid. This is
good as no wait code should rely on inferior_ptid.
2. Remove the use of general_thread from the 'T' packet processing.
The general_thread read here was only ever correct by chance, and we
shouldn't be using it this way.
3. Remove use of inferior_ptid from process_stop_event as this is
wrong, and will always be null_ptid now anyway.
4. When a stop_event has null_ptid due to a lack of thread-id (either
from a T packet or an S packet) then pick the first non exited thread
in the target and use that. This will be fine for single threaded
targets. A multi-thread or multi-inferior aware remote target
should be using T packets with a thread-id, so we give a warning if
the target is multi-threaded, and we are still missing a thread-id.
5. Extend the existing test that covered the T packet with missing
thread-id to also cover the S packet.
gdb/ChangeLog:
* remote.c (remote_target::remote_parse_stop_reply): Don't use the
general_thread if the stop reply is missing a thread-id.
(remote_target::process_stop_reply): Use the first non-exited
thread if the target didn't pass a thread-id.
* infrun.c (do_target_wait): Move call to
switch_to_inferior_no_thread to ....
(do_target_wait_1): ... here.
gdb/testsuite/ChangeLog:
* gdb.server/stop-reply-no-thread.exp: Add test where T packet is
disabled.
This patch redefines fputs_unfiltered in utils.c, with new behavior to
forward parameters to fputs_maybe_filtered. This makes
fputs_unfiltered identical to fputs_filtered, except filtering is
disabled.
Some callers of fputs_unfiltered have been updated to use ui_file_puts
where they were using other ui_file_* functions anyway for IO.
This fixes the problem I saw with \032\032post-prompt annotation being
flushed to stdout in the wrong order.
2020-02-05 Iain Buclaw <ibuclaw@gdcproject.org>
PR gdb/25190:
* gdb/remote-sim.c (gdb_os_write_stderr): Update.
* gdb/remote.c (remote_console_output): Update.
* gdb/ui-file.c (fputs_unfiltered): Rename to...
(ui_file_puts): ...this.
* gdb/ui-file.h (ui_file_puts): Add declaration.
* gdb/utils.c (emit_style_escape): Update.
(flush_wrap_buffer): Update.
(fputs_maybe_filtered): Update.
(fputs_unfiltered): Add function.
Change-Id: I17ed5078f71208344f2f8ab634a6518b1af6e213
This option allows to tell GDB to detect and possibly handle mismatched exec-files.
A recurrent problem with GDB is that GDB uses the wrong exec-file
when using the attach/detach commands successively.
Also, in case the user specifies a file on the command line but attaches
to the wrong PID, this error is not made visible and gives a not user
understandable behaviour.
For example:
$ gdb
...
(gdb) atta 2682 ############################################ PID running 'sleepers' executable
Attaching to process 2682
[New LWP 2683]
[New LWP 2684]
[New LWP 2685]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007f5ff829f603 in select () at ../sysdeps/unix/syscall-template.S:84
84 ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) det
Detaching from program: /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers, process 2682
[Inferior 1 (process 2682) detached]
(gdb) atta 31069 ############################################ PID running 'gdb' executable
Attaching to program: /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers, process 31069
Reading symbols from /lib64/ld-linux-x86-64.so.2...
Reading symbols from /usr/lib/debug/.build-id/60/6df9c355103e82140d513bc7a25a635591c153.debug...
0x00007f43c23478a0 in ?? ()
(gdb) bt
#0 0x00007f43c23478a0 in ?? ()
#1 0x0000558909e3ad91 in ?? ()
#2 0x0000202962646700 in ?? ()
#3 0x00007ffc69c74e70 in ?? ()
#4 0x000055890c1d2350 in ?? ()
#5 0x0000000000000000 in ?? ()
(gdb)
The second attach has kept the executable of the first attach.
(in this case, 31069 is the PID of a GDB, that has nothing to do
with the first determined 'sleepers' executable).
Similarly, if specifying an executable, but attaching to a wrong pid,
we get:
gdb /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers
...
Reading symbols from /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers...
(gdb) atta 31069 ############################################ PID running 'gdb' executable
Attaching to program: /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers, process 31069
Reading symbols from /lib64/ld-linux-x86-64.so.2...
Reading symbols from /usr/lib/debug/.build-id/60/6df9c355103e82140d513bc7a25a635591c153.debug...
0x00007f43c23478a0 in ?? ()
(gdb) bt
#0 0x00007f43c23478a0 in ?? ()
#1 0x0000558909e3ad91 in ?? ()
#2 0x0000202962646700 in ?? ()
#3 0x00007ffc69c74e70 in ?? ()
#4 0x000055890c1d2350 in ?? ()
#5 0x0000000000000000 in ?? ()
(gdb)
And it is unclear to the user what has happened/what is going wrong.
This patch series implements a new option:
(gdb) apropos exec-file-mismatch
set exec-file-mismatch -- Set exec-file-mismatch handling (ask|warn|off).
show exec-file-mismatch -- Show exec-file-mismatch handling (ask|warn|off).
(gdb) help set exec-file-mismatch
Set exec-file-mismatch handling (ask|warn|off).
Specifies how to handle a mismatch between the current exec-file name
loaded by GDB and the exec-file name automatically determined when attaching
to a process:
ask - warn the user and ask whether to load the determined exec-file.
warn - warn the user, but do not change the exec-file.
off - do not check for mismatch.
"ask" means: in case of mismatch between the current exec-file name
and the automatically determined exec-file name of the PID we are attaching to,
give a warning to the user and ask whether to load the automatically determined
exec-file.
"warn" means: in case of mismatch, just give a warning to the user.
"off" means: do not check for mismatch.
This fixes PR gdb/17626.
There was a previous trial to fix this PR.
See https://sourceware.org/ml/gdb-patches/2015-07/msg00118.html
This trial was however only fixing the problem for the automatically
determined executable files when doing attach.
It was differentiating the 'user specified executable files' ("sticky")
from the executable files automatically found by GDB.
But such user specified sticky executables are in most cases due
to a wrong manipulation by the user, giving unexpected results
such as backtrace showing no function like in the above example.
This patch ensures that whenever a process executable can be
determined, that the user is warned if there is a mismatch.
The same tests as above then give:
(gdb) atta 2682
Attaching to process 2682
[New LWP 2683]
[New LWP 2684]
[New LWP 2685]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007f5ff829f603 in select () at ../sysdeps/unix/syscall-template.S:84
84 ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) det
Detaching from program: /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers, process 2682
[Inferior 1 (process 2682) detached]
(gdb) atta 31069
Attaching to program: /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers, process 31069
warning: Mismatch between current exec-file /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers
and automatically determined exec-file /bd/home/philippe/gdb/git/build_fixes/gdb/gdb
exec-file-mismatch handling is currently "ask"
Load new symbol table from "/bd/home/philippe/gdb/git/build_fixes/gdb/gdb"? (y or n) y
Reading symbols from /bd/home/philippe/gdb/git/build_fixes/gdb/gdb...
Setting up the environment for debugging gdb.
...
Reading symbols from /usr/lib/debug/.build-id/60/6df9c355103e82140d513bc7a25a635591c153.debug...
0x00007f43c23478a0 in __poll_nocancel () at ../sysdeps/unix/syscall-template.S:84
84 ../sysdeps/unix/syscall-template.S: No such file or directory.
(top-gdb) bt
During symbol reading: incomplete CFI data; unspecified registers (e.g., rax) at 0x7f43c23478ad
During symbol reading: unsupported tag: 'DW_TAG_unspecified_type'
During symbol reading: cannot get low and high bounds for subprogram DIE at 0x12282a7
During symbol reading: Child DIE 0x12288ba and its abstract origin 0x1228b26 have different parents
During symbol reading: DW_AT_call_target target DIE has invalid low pc, for referencing DIE 0x1229540 [in module /bd/home/philippe/gdb/git/build_fixes/gdb/gdb]
#0 0x00007f43c23478a0 in __poll_nocancel () at ../sysdeps/unix/syscall-template.S:84
#1 0x0000558909e3ad91 in poll (__timeout=-1, __nfds=<optimized out>, __fds=<optimized out>) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46
#2 gdb_wait_for_event (block=block@entry=1) at ../../fixes/gdb/event-loop.c:772
#3 0x0000558909e3aef4 in gdb_do_one_event () at ../../fixes/gdb/event-loop.c:347
#4 0x0000558909e3b085 in gdb_do_one_event () at ../../fixes/gdb/common/common-exceptions.h:219
#5 start_event_loop () at ../../fixes/gdb/event-loop.c:371
During symbol reading: Member function "~_Sp_counted_base" (offset 0x1c69bf7) is virtual but the vtable offset is not specified
During symbol reading: Multiple children of DIE 0x1c8f5a0 refer to DIE 0x1c8f0ee as their abstract origin
#6 0x0000558909ed3b78 in captured_command_loop () at ../../fixes/gdb/main.c:331
#7 0x0000558909ed4b6d in captured_main (data=<optimized out>) at ../../fixes/gdb/main.c:1174
#8 gdb_main (args=<optimized out>) at ../../fixes/gdb/main.c:1190
#9 0x0000558909c1e9a8 in main (argc=<optimized out>, argv=<optimized out>) at ../../fixes/gdb/gdb.c:32
(top-gdb)
gdb /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers
...
Reading symbols from /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers...
(gdb) atta 31069
Attaching to program: /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers, process 31069
warning: Mismatch between current exec-file /home/philippe/valgrind/git/trunk_untouched/gdbserver_tests/sleepers
and automatically determined exec-file /bd/home/philippe/gdb/git/build_fixes/gdb/gdb
exec-file-mismatch handling is currently "ask"
Load new symbol table from "/bd/home/philippe/gdb/git/build_fixes/gdb/gdb"? (y or n) y
Reading symbols from /bd/home/philippe/gdb/git/build_fixes/gdb/gdb...
Setting up the environment for debugging gdb.
....
In other words, it now works as intuitively expected by the user.
If ever the user gave the correct executable on the command line,
then attached to the wrong pid, then confirmed loading the wrong executable,
the user can simply fix this by detaching, and attaching to the correct pid,
GDB will then tell again to the user that the exec-file might better
be loaded.
The default value of "ask" is chosen instead of e.g. "warn" as in most
cases, switching of executable will be the correct action,
and in any case, the user can decide to not load the executable,
as GDB asks a confirmation to the user to load the new executable.
For settings "ask" and "warn", the new function validate_exec_file ()
tries to get the inferior pid exec file and compares it with the current
exec file. In case of mismatch, it warns the user and optionally load
the executable.
This function is called in the attach_command implementation to cover
most cases of attaching to a running process.
It must also be called in remote.c, as the attach command is not supported
for all types of remote gdbserver.
gdb/ChangeLog
2020-01-25 Philippe Waroquiers <philippe.waroquiers@skynet.be>
* exec.c (exec_file_mismatch_names, exec_file_mismatch_mode)
(show_exec_file_mismatch_command, set_exec_file_mismatch_command)
(validate_exec_file): New variables, enums, functions.
(exec_file_locate_attach, print_section_info): Style the filenames.
(_initialize_exec): Install show_exec_file_mismatch_command and
set_exec_file_mismatch_command.
* gdbcore.h (validate_exec_file): Declare.
* infcmd.c (attach_command): Call validate_exec_file.
* remote.c ( remote_target::remote_add_inferior): Likewise.
This commit extends the CLI a bit for multi-target, in three ways.
#1 - New "info connections" command.
This is a new command that lists the open connections (process_stratum
targets). For example, if you're debugging two remote connections, a
couple local/native processes, and a core dump, all at the same time,
you might see something like this:
(gdb) info connections
Num What Description
1 remote 192.168.0.1:9999 Remote serial target in gdb-specific protocol
2 remote 192.168.0.2:9998 Remote serial target in gdb-specific protocol
* 3 native Native process
4 core Local core dump file
#2 - New "info inferiors" "Connection" column
You'll also see a new matching "Connection" column in "info
inferiors", showing you which connection an inferior is bound to:
(gdb) info inferiors
Num Description Connection Executable
1 process 18526 1 (remote 192.168.0.1:9999) target:/tmp/a.out
2 process 18531 2 (remote 192.168.0.2:9998) target:/tmp/a.out
3 process 19115 3 (native) /tmp/prog1
4 process 6286 4 (core) myprogram
* 5 process 19122 3 (native) /bin/hello
#3 - Makes "add-inferior" show the inferior's target connection
"add-inferior" now shows you the connection you've just bound the
inferior to, which is the current process_stratum target:
(gdb) add-inferior
[New inferior 2]
Added inferior 2 on connection 1 (extended-remote localhost:2346)
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* Makefile.in (COMMON_SFILES): Add target-connection.c.
* inferior.c (uiout_field_connection): New function.
(print_inferior): Add new "connection-id" column.
(add_inferior_command): Show connection number/string of added
inferior.
* process-stratum-target.h
(process_stratum_target::connection_string): New virtual method.
(process_stratum_target::connection_number): New field.
* remote.c (remote_target::connection_string): New override.
* target-connection.c: New file.
* target-connection.h: New file.
* target.c (decref_target): Remove process_stratum targets from
the connection list.
(target_stack::push): Add process_stratum targets to the
connection list.
gdb/testsuite/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* gdb.base/kill-detach-inferiors-cmd.exp: Adjust expected output
of "add-inferior".
* gdb.base/quit-live.exp: Likewise.
* gdb.base/remote-exec-file.exp: Likewise.
* gdb.guile/scm-progspace.exp: Likewise.
* gdb.linespec/linespec.exp: Likewise.
* gdb.mi/new-ui-mi-sync.exp: Likewise.
* gdb.mi/user-selected-context-sync.exp: Likewise.
* gdb.multi/multi-target.exp (setup): Add "info connection" and
"info inferiors" tests.
* gdb.multi/remove-inferiors.exp: Adjust expected output of
"add-inferior".
* gdb.multi/watchpoint-multi.exp: Likewise.
* gdb.python/py-inferior.exp: Likewise.
* gdb.server/extended-remote-restart.exp: Likewise.
* gdb.threads/fork-plus-threads.exp: Adjust expected output of
"info inferiors".
* gdb.threads/forking-threads-plus-breakpoint.exp: Likewise.
* gdb.trace/report.exp: Likewise.
This commit adds multi-target support to GDB. What this means is that
with this commit, GDB can now be connected to different targets at the
same time. E.g., you can debug a live native process and a core dump
at the same time, connect to multiple gdbservers, etc.
Actually, the word "target" is overloaded in gdb. We already have a
target stack, with pushes several target_ops instances on top of one
another. We also have "info target" already, which means something
completely different to what this patch does.
So from here on, I'll be using the "target connections" term, to mean
an open process_stratum target, pushed on a target stack. This patch
makes gdb have multiple target stacks, and multiple process_stratum
targets open simultaneously. The user-visible changes / commands will
also use this terminology, but of course it's all open to debate.
User-interface-wise, not that much changes. The main difference is
that each inferior may have its own target connection.
A target connection (e.g., a target extended-remote connection) may
support debugging multiple processes, just as before.
Say you're debugging against gdbserver in extended-remote mode, and
you do "add-inferior" to prepare to spawn a new process, like:
(gdb) target extended-remote :9999
...
(gdb) start
...
(gdb) add-inferior
Added inferior 2
(gdb) inferior 2
[Switching to inferior 2 [<null>] (<noexec>)]
(gdb) file a.out
...
(gdb) start
...
At this point, you have two inferiors connected to the same gdbserver.
With this commit, GDB will maintain a target stack per inferior,
instead of a global target stack.
To preserve the behavior above, by default, "add-inferior" makes the
new inferior inherit a copy of the target stack of the current
inferior. Same across a fork - the child inherits a copy of the
target stack of the parent. While the target stacks are copied, the
targets themselves are not. Instead, target_ops is made a
refcounted_object, which means that target_ops instances are
refcounted, which each inferior counting for a reference.
What if you want to create an inferior and connect it to some _other_
target? For that, this commit introduces a new "add-inferior
-no-connection" option that makes the new inferior not share the
current inferior's target. So you could do:
(gdb) target extended-remote :9999
Remote debugging using :9999
...
(gdb) add-inferior -no-connection
[New inferior 2]
Added inferior 2
(gdb) inferior 2
[Switching to inferior 2 [<null>] (<noexec>)]
(gdb) info inferiors
Num Description Executable
1 process 18401 target:/home/pedro/tmp/main
* 2 <null>
(gdb) tar extended-remote :10000
Remote debugging using :10000
...
(gdb) info inferiors
Num Description Executable
1 process 18401 target:/home/pedro/tmp/main
* 2 process 18450 target:/home/pedro/tmp/main
(gdb)
A following patch will extended "info inferiors" to include a column
indicating which connection an inferior is bound to, along with a
couple other UI tweaks.
Other than that, debugging is the same as before. Users interact with
inferiors and threads as before. The only difference is that
inferiors may be bound to processes running in different machines.
That's pretty much all there is to it in terms of noticeable UI
changes.
On to implementation.
Since we can be connected to different systems at the same time, a
ptid_t is no longer a unique identifier. Instead a thread can be
identified by a pair of ptid_t and 'process_stratum_target *', the
later being the instance of the process_stratum target that owns the
process/thread. Note that process_stratum_target inherits from
target_ops, and all process_stratum targets inherit from
process_stratum_target. In earlier patches, many places in gdb were
converted to refer to threads by thread_info pointer instead of
ptid_t, but there are still places in gdb where we start with a
pid/tid and need to find the corresponding inferior or thread_info
objects. So you'll see in the patch many places adding a
process_stratum_target parameter to functions that used to take only a
ptid_t.
Since each inferior has its own target stack now, we can always find
the process_stratum target for an inferior. That is done via a
inf->process_target() convenience method.
Since each inferior has its own target stack, we need to handle the
"beneath" calls when servicing target calls. The solution I settled
with is just to make sure to switch the current inferior to the
inferior you want before making a target call. Not relying on global
context is just not feasible in current GDB. Fortunately, there
aren't that many places that need to do that, because generally most
code that calls target methods already has the current context
pointing to the right inferior/thread. Note, to emphasize -- there's
no method to "switch to this target stack". Instead, you switch the
current inferior, and that implicitly switches the target stack.
In some spots, we need to iterate over all inferiors so that we reach
all target stacks.
Native targets are still singletons. There's always only a single
instance of such targets.
Remote targets however, we'll have one instance per remote connection.
The exec target is still a singleton. There's only one instance. I
did not see the point of instanciating more than one exec_target
object.
After vfork, we need to make sure to push the exec target on the new
inferior. See exec_on_vfork.
For type safety, functions that need a {target, ptid} pair to identify
a thread, take a process_stratum_target pointer for target parameter
instead of target_ops *. Some shared code in gdb/nat/ also need to
gain a target pointer parameter. This poses an issue, since gdbserver
doesn't have process_stratum_target, only target_ops. To fix this,
this commit renames gdbserver's target_ops to process_stratum_target.
I think this makes sense. There's no concept of target stack in
gdbserver, and gdbserver's target_ops really implements a
process_stratum-like target.
The thread and inferior iterator functions also gain
process_stratum_target parameters. These are used to be able to
iterate over threads and inferiors of a given target. Following usual
conventions, if the target pointer is null, then we iterate over
threads and inferiors of all targets.
I tried converting "add-inferior" to the gdb::option framework, as a
preparatory patch, but that stumbled on the fact that gdb::option does
not support file options yet, for "add-inferior -exec". I have a WIP
patchset that adds that, but it's not a trivial patch, mainly due to
need to integrate readline's filename completion, so I deferred that
to some other time.
In infrun.c/infcmd.c, the main change is that we need to poll events
out of all targets. See do_target_wait. Right after collecting an
event, we switch the current inferior to an inferior bound to the
target that reported the event, so that target methods can be used
while handling the event. This makes most of the code transparent to
multi-targets. See fetch_inferior_event.
infrun.c:stop_all_threads is interesting -- in this function we need
to stop all threads of all targets. What the function does is send an
asynchronous stop request to all threads, and then synchronously waits
for events, with target_wait, rinse repeat, until all it finds are
stopped threads. Now that we have multiple targets, it's not
efficient to synchronously block in target_wait waiting for events out
of one target. Instead, we implement a mini event loop, with
interruptible_select, select'ing on one file descriptor per target.
For this to work, we need to be able to ask the target for a waitable
file descriptor. Such file descriptors already exist, they are the
descriptors registered in the main event loop with add_file_handler,
inside the target_async implementations. This commit adds a new
target_async_wait_fd target method that just returns the file
descriptor in question. See wait_one / stop_all_threads in infrun.c.
The 'threads_executing' global is made a per-target variable. Since
it is only relevant to process_stratum_target targets, this is where
it is put, instead of in target_ops.
You'll notice that remote.c includes some FIXME notes. These refer to
the fact that the global arrays that hold data for the remote packets
supported are still globals. For example, if we connect to two
different servers/stubs, then each might support different remote
protocol features. They might even be different architectures, like
e.g., one ARM baremetal stub, and a x86 gdbserver, to debug a
host/controller scenario as a single program. That isn't going to
work correctly today, because of said globals. I'm leaving fixing
that for another pass, since it does not appear to be trivial, and I'd
rather land the base work first. It's already useful to be able to
debug multiple instances of the same server (e.g., a distributed
cluster, where you have full control over the servers installed), so I
think as is it's already reasonable incremental progress.
Current limitations:
- You can only resume more that one target at the same time if all
targets support asynchronous debugging, and support non-stop mode.
It should be possible to support mixed all-stop + non-stop
backends, but that is left for another time. This means that
currently in order to do multi-target with gdbserver you need to
issue "maint set target-non-stop on". I would like to make that
mode be the default, but we're not there yet. Note that I'm
talking about how the target backend works, only. User-visible
all-stop mode works just fine.
- As explained above, connecting to different remote servers at the
same time is likely to produce bad results if they don't support the
exact set of RSP features.
FreeBSD updates courtesy of John Baldwin.
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
John Baldwin <jhb@FreeBSD.org>
* aarch64-linux-nat.c
(aarch64_linux_nat_target::thread_architecture): Adjust.
* ada-tasks.c (print_ada_task_info): Adjust find_thread_ptid call.
(task_command_1): Likewise.
* aix-thread.c (sync_threadlists, aix_thread_target::resume)
(aix_thread_target::wait, aix_thread_target::fetch_registers)
(aix_thread_target::store_registers)
(aix_thread_target::thread_alive): Adjust.
* amd64-fbsd-tdep.c: Include "inferior.h".
(amd64fbsd_get_thread_local_address): Pass down target.
* amd64-linux-nat.c (ps_get_thread_area): Use ps_prochandle
thread's gdbarch instead of target_gdbarch.
* break-catch-sig.c (signal_catchpoint_print_it): Adjust call to
get_last_target_status.
* break-catch-syscall.c (print_it_catch_syscall): Likewise.
* breakpoint.c (breakpoints_should_be_inserted_now): Consider all
inferiors.
(update_inserted_breakpoint_locations): Skip if inferiors with no
execution.
(update_global_location_list): When handling moribund locations,
find representative inferior for location's pspace, and use thread
count of its process_stratum target.
* bsd-kvm.c (bsd_kvm_target_open): Pass target down.
* bsd-uthread.c (bsd_uthread_target::wait): Use
as_process_stratum_target and adjust thread_change_ptid and
add_thread calls.
(bsd_uthread_target::update_thread_list): Use
as_process_stratum_target and adjust find_thread_ptid,
thread_change_ptid and add_thread calls.
* btrace.c (maint_btrace_packet_history_cmd): Adjust
find_thread_ptid call.
* corelow.c (add_to_thread_list): Adjust add_thread call.
(core_target_open): Adjust add_thread_silent and thread_count
calls.
(core_target::pid_to_str): Adjust find_inferior_ptid call.
* ctf.c (ctf_target_open): Adjust add_thread_silent call.
* event-top.c (async_disconnect): Pop targets from all inferiors.
* exec.c (add_target_sections): Push exec target on all inferiors
sharing the program space.
(remove_target_sections): Remove the exec target from all
inferiors sharing the program space.
(exec_on_vfork): New.
* exec.h (exec_on_vfork): Declare.
* fbsd-nat.c (fbsd_add_threads): Add fbsd_nat_target parameter.
Pass it down.
(fbsd_nat_target::update_thread_list): Adjust.
(fbsd_nat_target::resume): Adjust.
(fbsd_handle_debug_trap): Add fbsd_nat_target parameter. Pass it
down.
(fbsd_nat_target::wait, fbsd_nat_target::post_attach): Adjust.
* fbsd-tdep.c (fbsd_corefile_thread): Adjust
get_thread_arch_regcache call.
* fork-child.c (gdb_startup_inferior): Pass target down to
startup_inferior and set_executing.
* gdbthread.h (struct process_stratum_target): Forward declare.
(add_thread, add_thread_silent, add_thread_with_info)
(in_thread_list): Add process_stratum_target parameter.
(find_thread_ptid(inferior*, ptid_t)): New overload.
(find_thread_ptid, thread_change_ptid): Add process_stratum_target
parameter.
(all_threads()): Delete overload.
(all_threads, all_non_exited_threads): Add process_stratum_target
parameter.
(all_threads_safe): Use brace initialization.
(thread_count): Add process_stratum_target parameter.
(set_resumed, set_running, set_stop_requested, set_executing)
(threads_are_executing, finish_thread_state): Add
process_stratum_target parameter.
(switch_to_thread): Use is_current_thread.
* i386-fbsd-tdep.c: Include "inferior.h".
(i386fbsd_get_thread_local_address): Pass down target.
* i386-linux-nat.c (i386_linux_nat_target::low_resume): Adjust.
* inf-child.c (inf_child_target::maybe_unpush_target): Remove
have_inferiors check.
* inf-ptrace.c (inf_ptrace_target::create_inferior)
(inf_ptrace_target::attach): Adjust.
* infcall.c (run_inferior_call): Adjust.
* infcmd.c (run_command_1): Pass target to
scoped_finish_thread_state.
(proceed_thread_callback): Skip inferiors with no execution.
(continue_command): Rename 'all_threads' local to avoid hiding
'all_threads' function. Adjust get_last_target_status call.
(prepare_one_step): Adjust set_running call.
(signal_command): Use user_visible_resume_target. Compare thread
pointers instead of inferior_ptid.
(info_program_command): Adjust to pass down target.
(attach_command): Mark target's 'thread_executing' flag.
(stop_current_target_threads_ns): New, factored out from ...
(interrupt_target_1): ... this. Switch inferior before making
target calls.
* inferior-iter.h
(struct all_inferiors_iterator, struct all_inferiors_range)
(struct all_inferiors_safe_range)
(struct all_non_exited_inferiors_range): Filter on
process_stratum_target too. Remove explicit.
* inferior.c (inferior::inferior): Push dummy target on target
stack.
(find_inferior_pid, find_inferior_ptid, number_of_live_inferiors):
Add process_stratum_target parameter, and pass it down.
(have_live_inferiors): Adjust.
(switch_to_inferior_and_push_target): New.
(add_inferior_command, clone_inferior_command): Handle
"-no-connection" parameter. Use
switch_to_inferior_and_push_target.
(_initialize_inferior): Mention "-no-connection" option in
the help of "add-inferior" and "clone-inferior" commands.
* inferior.h: Include "process-stratum-target.h".
(interrupt_target_1): Use bool.
(struct inferior) <push_target, unpush_target, target_is_pushed,
find_target_beneath, top_target, process_target, target_at,
m_stack>: New.
(discard_all_inferiors): Delete.
(find_inferior_pid, find_inferior_ptid, number_of_live_inferiors)
(all_inferiors, all_non_exited_inferiors): Add
process_stratum_target parameter.
* infrun.c: Include "gdb_select.h" and <unordered_map>.
(target_last_proc_target): New global.
(follow_fork_inferior): Push target on new inferior. Pass target
to add_thread_silent. Call exec_on_vfork. Handle target's
reference count.
(follow_fork): Adjust get_last_target_status call. Also consider
target.
(follow_exec): Push target on new inferior.
(struct execution_control_state) <target>: New field.
(user_visible_resume_target): New.
(do_target_resume): Call target_async.
(resume_1): Set target's threads_executing flag. Consider resume
target.
(commit_resume_all_targets): New.
(proceed): Also consider resume target. Skip threads of inferiors
with no execution. Commit resumtion in all targets.
(start_remote): Pass current inferior to wait_for_inferior.
(infrun_thread_stop_requested): Consider target as well. Pass
thread_info pointer to clear_inline_frame_state instead of ptid.
(infrun_thread_thread_exit): Consider target as well.
(random_pending_event_thread): New inferior parameter. Use it.
(do_target_wait): Rename to ...
(do_target_wait_1): ... this. Add inferior parameter, and pass it
down.
(threads_are_resumed_pending_p, do_target_wait): New.
(prepare_for_detach): Adjust calls.
(wait_for_inferior): New inferior parameter. Handle it. Use
do_target_wait_1 instead of do_target_wait.
(fetch_inferior_event): Adjust. Switch to representative
inferior. Pass target down.
(set_last_target_status): Add process_stratum_target parameter.
Save target in global.
(get_last_target_status): Add process_stratum_target parameter and
handle it.
(nullify_last_target_wait_ptid): Clear 'target_last_proc_target'.
(context_switch): Check inferior_ptid == null_ptid before calling
inferior_thread().
(get_inferior_stop_soon): Pass down target.
(wait_one): Rename to ...
(poll_one_curr_target): ... this.
(struct wait_one_event): New.
(wait_one): New.
(stop_all_threads): Adjust.
(handle_no_resumed, handle_inferior_event): Adjust to consider the
event's target.
(switch_back_to_stepped_thread): Also consider target.
(print_stop_event): Update.
(normal_stop): Update. Also consider the resume target.
* infrun.h (wait_for_inferior): Remove declaration.
(user_visible_resume_target): New declaration.
(get_last_target_status, set_last_target_status): New
process_stratum_target parameter.
* inline-frame.c (clear_inline_frame_state(ptid_t)): Add
process_stratum_target parameter, and use it.
(clear_inline_frame_state (thread_info*)): New.
* inline-frame.c (clear_inline_frame_state(ptid_t)): Add
process_stratum_target parameter.
(clear_inline_frame_state (thread_info*)): Declare.
* linux-fork.c (delete_checkpoint_command): Pass target down to
find_thread_ptid.
(checkpoint_command): Adjust.
* linux-nat.c (linux_nat_target::follow_fork): Switch to thread
instead of just tweaking inferior_ptid.
(linux_nat_switch_fork): Pass target down to thread_change_ptid.
(exit_lwp): Pass target down to find_thread_ptid.
(attach_proc_task_lwp_callback): Pass target down to
add_thread/set_running/set_executing.
(linux_nat_target::attach): Pass target down to
thread_change_ptid.
(get_detach_signal): Pass target down to find_thread_ptid.
Consider last target status's target.
(linux_resume_one_lwp_throw, resume_lwp)
(linux_handle_syscall_trap, linux_handle_extended_wait, wait_lwp)
(stop_wait_callback, save_stop_reason, linux_nat_filter_event)
(linux_nat_wait_1, resume_stopped_resumed_lwps): Pass target down.
(linux_nat_target::async_wait_fd): New.
(linux_nat_stop_lwp, linux_nat_target::thread_address_space): Pass
target down.
* linux-nat.h (linux_nat_target::async_wait_fd): Declare.
* linux-tdep.c (get_thread_arch_regcache): Pass target down.
* linux-thread-db.c (struct thread_db_info::process_target): New
field.
(add_thread_db_info): Save target.
(get_thread_db_info): New process_stratum_target parameter. Also
match target.
(delete_thread_db_info): New process_stratum_target parameter.
Also match target.
(thread_from_lwp): Adjust to pass down target.
(thread_db_notice_clone): Pass down target.
(check_thread_db_callback): Pass down target.
(try_thread_db_load_1): Always push the thread_db target.
(try_thread_db_load, record_thread): Pass target down.
(thread_db_target::detach): Pass target down. Always unpush the
thread_db target.
(thread_db_target::wait, thread_db_target::mourn_inferior): Pass
target down. Always unpush the thread_db target.
(find_new_threads_callback, thread_db_find_new_threads_2)
(thread_db_target::update_thread_list): Pass target down.
(thread_db_target::pid_to_str): Pass current inferior down.
(thread_db_target::get_thread_local_address): Pass target down.
(thread_db_target::resume, maintenance_check_libthread_db): Pass
target down.
* nto-procfs.c (nto_procfs_target::update_thread_list): Adjust.
* procfs.c (procfs_target::procfs_init_inferior): Declare.
(proc_set_current_signal, do_attach, procfs_target::wait): Adjust.
(procfs_init_inferior): Rename to ...
(procfs_target::procfs_init_inferior): ... this and adjust.
(procfs_target::create_inferior, procfs_notice_thread)
(procfs_do_thread_registers): Adjust.
* ppc-fbsd-tdep.c: Include "inferior.h".
(ppcfbsd_get_thread_local_address): Pass down target.
* proc-service.c (ps_xfer_memory): Switch current inferior and
program space as well.
(get_ps_regcache): Pass target down.
* process-stratum-target.c
(process_stratum_target::thread_address_space)
(process_stratum_target::thread_architecture): Pass target down.
* process-stratum-target.h
(process_stratum_target::threads_executing): New field.
(as_process_stratum_target): New.
* ravenscar-thread.c
(ravenscar_thread_target::update_inferior_ptid): Pass target down.
(ravenscar_thread_target::wait, ravenscar_add_thread): Pass target
down.
* record-btrace.c (record_btrace_target::info_record): Adjust.
(record_btrace_target::record_method)
(record_btrace_target::record_is_replaying)
(record_btrace_target::fetch_registers)
(get_thread_current_frame_id, record_btrace_target::resume)
(record_btrace_target::wait, record_btrace_target::stop): Pass
target down.
* record-full.c (record_full_wait_1): Switch to event thread.
Pass target down.
* regcache.c (regcache::regcache)
(get_thread_arch_aspace_regcache, get_thread_arch_regcache): Add
process_stratum_target parameter and handle it.
(current_thread_target): New global.
(get_thread_regcache): Add process_stratum_target parameter and
handle it. Switch inferior before calling target method.
(get_thread_regcache): Pass target down.
(get_thread_regcache_for_ptid): Pass target down.
(registers_changed_ptid): Add process_stratum_target parameter and
handle it.
(registers_changed_thread, registers_changed): Pass target down.
(test_get_thread_arch_aspace_regcache): New.
(current_regcache_test): Define a couple local test_target_ops
instances and use them for testing.
(readwrite_regcache): Pass process_stratum_target parameter.
(cooked_read_test, cooked_write_test): Pass mock_target down.
* regcache.h (get_thread_regcache, get_thread_arch_regcache)
(get_thread_arch_aspace_regcache): Add process_stratum_target
parameter.
(regcache::target): New method.
(regcache::regcache, regcache::get_thread_arch_aspace_regcache)
(regcache::registers_changed_ptid): Add process_stratum_target
parameter.
(regcache::m_target): New field.
(registers_changed_ptid): Add process_stratum_target parameter.
* remote.c (remote_state::supports_vCont_probed): New field.
(remote_target::async_wait_fd): New method.
(remote_unpush_and_throw): Add remote_target parameter.
(get_current_remote_target): Adjust.
(remote_target::remote_add_inferior): Push target.
(remote_target::remote_add_thread)
(remote_target::remote_notice_new_inferior)
(get_remote_thread_info): Pass target down.
(remote_target::update_thread_list): Skip threads of inferiors
bound to other targets. (remote_target::close): Don't discard
inferiors. (remote_target::add_current_inferior_and_thread)
(remote_target::process_initial_stop_replies)
(remote_target::start_remote)
(remote_target::remote_serial_quit_handler): Pass down target.
(remote_target::remote_unpush_target): New remote_target
parameter. Unpush the target from all inferiors.
(remote_target::remote_unpush_and_throw): New remote_target
parameter. Pass it down.
(remote_target::open_1): Check whether the current inferior has
execution instead of checking whether any inferior is live. Pass
target down.
(remote_target::remote_detach_1): Pass down target. Use
remote_unpush_target.
(extended_remote_target::attach): Pass down target.
(remote_target::remote_vcont_probe): Set supports_vCont_probed.
(remote_target::append_resumption): Pass down target.
(remote_target::append_pending_thread_resumptions)
(remote_target::remote_resume_with_hc, remote_target::resume)
(remote_target::commit_resume): Pass down target.
(remote_target::remote_stop_ns): Check supports_vCont_probed.
(remote_target::interrupt_query)
(remote_target::remove_new_fork_children)
(remote_target::check_pending_events_prevent_wildcard_vcont)
(remote_target::remote_parse_stop_reply)
(remote_target::process_stop_reply): Pass down target.
(first_remote_resumed_thread): New remote_target parameter. Pass
it down.
(remote_target::wait_as): Pass down target.
(unpush_and_perror): New remote_target parameter. Pass it down.
(remote_target::readchar, remote_target::remote_serial_write)
(remote_target::getpkt_or_notif_sane_1)
(remote_target::kill_new_fork_children, remote_target::kill): Pass
down target.
(remote_target::mourn_inferior): Pass down target. Use
remote_unpush_target.
(remote_target::core_of_thread)
(remote_target::remote_btrace_maybe_reopen): Pass down target.
(remote_target::pid_to_exec_file)
(remote_target::thread_handle_to_thread_info): Pass down target.
(remote_target::async_wait_fd): New.
* riscv-fbsd-tdep.c: Include "inferior.h".
(riscv_fbsd_get_thread_local_address): Pass down target.
* sol2-tdep.c (sol2_core_pid_to_str): Pass down target.
* sol-thread.c (sol_thread_target::wait, ps_lgetregs, ps_lsetregs)
(ps_lgetfpregs, ps_lsetfpregs, sol_update_thread_list_callback):
Adjust.
* solib-spu.c (spu_skip_standalone_loader): Pass down target.
* solib-svr4.c (enable_break): Pass down target.
* spu-multiarch.c (parse_spufs_run): Pass down target.
* spu-tdep.c (spu2ppu_sniffer): Pass down target.
* target-delegates.c: Regenerate.
* target.c (g_target_stack): Delete.
(current_top_target): Return the current inferior's top target.
(target_has_execution_1): Refer to the passed-in inferior's top
target.
(target_supports_terminal_ours): Check whether the initial
inferior was already created.
(decref_target): New.
(target_stack::push): Incref/decref the target.
(push_target, push_target, unpush_target): Adjust.
(target_stack::unpush): Defref target.
(target_is_pushed): Return bool. Adjust to refer to the current
inferior's target stack.
(dispose_inferior): Delete, and inline parts ...
(target_preopen): ... here. Only dispose of the current inferior.
(target_detach): Hold strong target reference while detaching.
Pass target down.
(target_thread_name): Add assertion.
(target_resume): Pass down target.
(target_ops::beneath, find_target_at): Adjust to refer to the
current inferior's target stack.
(get_dummy_target): New.
(target_pass_ctrlc): Pass the Ctrl-C to the first inferior that
has a thread running.
(initialize_targets): Rename to ...
(_initialize_target): ... this.
* target.h: Include "gdbsupport/refcounted-object.h".
(struct target_ops): Inherit refcounted_object.
(target_ops::shortname, target_ops::longname): Make const.
(target_ops::async_wait_fd): New method.
(decref_target): Declare.
(struct target_ops_ref_policy): New.
(target_ops_ref): New typedef.
(get_dummy_target): Declare function.
(target_is_pushed): Return bool.
* thread-iter.c (all_matching_threads_iterator::m_inf_matches)
(all_matching_threads_iterator::all_matching_threads_iterator):
Handle filter target.
* thread-iter.h (struct all_matching_threads_iterator, struct
all_matching_threads_range, class all_non_exited_threads_range):
Filter by target too. Remove explicit.
* thread.c (threads_executing): Delete.
(inferior_thread): Pass down current inferior.
(clear_thread_inferior_resources): Pass down thread pointer
instead of ptid_t.
(add_thread_silent, add_thread_with_info, add_thread): Add
process_stratum_target parameter. Use it for thread and inferior
searches.
(is_current_thread): New.
(thread_info::deletable): Use it.
(find_thread_ptid, thread_count, in_thread_list)
(thread_change_ptid, set_resumed, set_running): New
process_stratum_target parameter. Pass it down.
(set_executing): New process_stratum_target parameter. Pass it
down. Adjust reference to 'threads_executing'.
(threads_are_executing): New process_stratum_target parameter.
Adjust reference to 'threads_executing'.
(set_stop_requested, finish_thread_state): New
process_stratum_target parameter. Pass it down.
(switch_to_thread): Also match inferior.
(switch_to_thread): New process_stratum_target parameter. Pass it
down.
(update_threads_executing): Reimplement.
* top.c (quit_force): Pop targets from all inferior.
(gdb_init): Don't call initialize_targets.
* windows-nat.c (windows_nat_target) <get_windows_debug_event>:
Declare.
(windows_add_thread, windows_delete_thread): Adjust.
(get_windows_debug_event): Rename to ...
(windows_nat_target::get_windows_debug_event): ... this. Adjust.
* tracefile-tfile.c (tfile_target_open): Pass down target.
* gdbsupport/common-gdbthread.h (struct process_stratum_target):
Forward declare.
(switch_to_thread): Add process_stratum_target parameter.
* mi/mi-interp.c (mi_on_resume_1): Add process_stratum_target
parameter. Use it.
(mi_on_resume): Pass target down.
* nat/fork-inferior.c (startup_inferior): Add
process_stratum_target parameter. Pass it down.
* nat/fork-inferior.h (startup_inferior): Add
process_stratum_target parameter.
* python/py-threadevent.c (py_get_event_thread): Pass target down.
gdb/gdbserver/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* fork-child.c (post_fork_inferior): Pass target down to
startup_inferior.
* inferiors.c (switch_to_thread): Add process_stratum_target
parameter.
* lynx-low.c (lynx_target_ops): Now a process_stratum_target.
* nto-low.c (nto_target_ops): Now a process_stratum_target.
* linux-low.c (linux_target_ops): Now a process_stratum_target.
* remote-utils.c (prepare_resume_reply): Pass the target to
switch_to_thread.
* target.c (the_target): Now a process_stratum_target.
(done_accessing_memory): Pass the target to switch_to_thread.
(set_target_ops): Ajust to use process_stratum_target.
* target.h (struct target_ops): Rename to ...
(struct process_stratum_target): ... this.
(the_target, set_target_ops): Adjust.
(prepare_to_access_memory): Adjust comment.
* win32-low.c (child_xfer_memory): Adjust to use
process_stratum_target.
(win32_target_ops): Now a process_stratum_target.
Another bug exposed by gdb.server/extended-remote-restart.exp in the
multi-target work is that remote_target::start_remote can leave
inferior_ptid and current_inferior() out of sync:
(top-gdb) p current_inferior_->pid
$1 = 29541
(top-gdb) p inferior_ptid
$2 = {m_pid = 29540, m_lwp = 29540, m_tid = 0}
This is caused by writing to inferior_ptid directly instead of using
switch_to_thread. Also, "inferior_list->thread_list->ptid" assumes
that we want the first thread of the first inferior, but that inferior
may not have threads, or with multi-target, that target may be
connected to some other target.
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* remote.c (remote_target::start_remote): Don't set inferior_ptid
directly. Instead find the first thread in the thread list and
use switch_to_thread.
The multi-target patch will change the remote target's behavior when:
- the current inferior is connected to an extended-remote target.
- the current inferior is attached to any process.
- some other inferior than than the current one is live.
In current master, we get:
(gdb) tar extended-remote :9999
A program is being debugged already. Kill it? (y or n)
While after multi-target, since each inferior may have its own target
connection, we'll get:
(gdb) tar extended-remote :9999
Already connected to a remote target. Disconnect? (y or n)
That change made gdb.server/extended-remote-restart.exp expose a gdb
bug, because it made "target remote", via gdb_reconnect, just
disconnect from the previous connection, while in current master that
command would kill the inferior before disconnecting. In turn, that
would make a multi-target gdb find processes already running under
control of gdbserver as soon as it reconnects, while in current master
there is never any process around when gdb reconnects, since they'd
all been killed prior to disconnection.
The bug this exposed is that remote_target::remote_add_inferior was
always reusing current_inferior() for the new process, even if the
current inferior was already bound to a process. In the testcase's
case, when we reconnect, the remote is debugging two processes. So
we'd bind the first remote process to the empty current inferior the
first time, and then bind the second remote process to the same
inferior again, essencially losing track of the first process. That
resulted in failed assertions when we look up the inferior for the
first process by PID. The fix is to still prefer binding to the
current inferior (so that plain "target remote" keeps doing what you'd
expect), but not reuse the current inferior if it is already bound to
a process.
This patch tweaks the test to explicitly disconnect before
reconnecting, to avoid GDB killing processes, thus making current GDB
behave the same as it will behave when the multi-target work lands.
That change alone without the GDB fix exposes the bug like so:
(gdb) PASS: gdb.server/extended-remote-restart.exp: kill: 0, follow-child 0: disconnect
target extended-remote localhost:2350
Remote debugging using localhost:2350
src/gdb/thread.c:93: internal-error: thread_info* inferior_thread(): Assertion `tp' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
The original bug that the testcase was written for was related to
killing, (git 9d4a934ce6 ("gdb: Fix assert for extended-remote
target (PR gdb/18050)")), but since the testcase tries reconnecting
with both explicitly killing and not explicitly killing, I think we're
covering the original bug with this testcase change.
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* remote.c (remote_target::remote_add_inferior): Don't bind a
process to the current inferior if the current inferior is already
bound to a process.
gdb/testsuite/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* gdb.server/extended-remote-restart.exp (test_reload): Explicitly
disconnect before reconnecting.
The multi-target patch makes inferior_ptid point to null_ptid before
calling into target_wait, which catches bad uses of inferior_ptid,
since the current selected thread in gdb shouldn't have much relation
to the thread that reports an event.
One such bad use is found in remote_target::remote_parse_stop_reply,
where we handle the 'W' or 'X' packets (process exit), and the remote
target does not support the multi-process extensions, i.e., it does
not report the PID of the process that exited.
With the multi-target patch, that would result in a failed assertion,
trying to find the inferior for process pid 0.
gdb/ChangeLog:
2020-01-10 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Pedro Alves <palves@redhat.com>
* remote.c (remote_target::remote_parse_stop_reply) <W/X packets>:
If no process is specified, return null_ptid instead of
inferior_ptid.
(remote_target::wait_as): Handle TARGET_WAITKIND_EXITED /
TARGET_WAITKIND_SIGNALLED with no pid.
gdb/testsuite/ChangeLog:
2020-01-10 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Pedro Alves <palves@redhat.com>
* gdb.server/connect-without-multi-process.exp: Also test
continuing to end.
With current master, on a Fedora 27 machine with a kernel with buggy
watchpoint support, I see:
(gdb) PASS: gdb.threads/watchpoint-fork.exp: parent: singlethreaded: hardware breakpoints work
continue
Continuing.
warning: Remote failure reply: E01
Remote communication error. Target disconnected.: Connection reset by peer.
(gdb) FAIL: gdb.threads/watchpoint-fork.exp: parent: singlethreaded: watchpoints work
continue
The program is not being run.
(gdb) FAIL: gdb.threads/watchpoint-fork.exp: parent: singlethreaded: breakpoint after the first fork (the program is no longer running)
The FAILs themselves aren't what's interesting here. What is
interesting is that with the main multi-target patch applied, I was getting this:
(gdb) PASS: gdb.threads/watchpoint-fork.exp: parent: singlethreaded: hardware breakpoints work
continue
Continuing.
warning: Remote failure reply: E01
/home/pedro/brno/pedro/gdb/binutils-gdb-2/build/../src/gdb/inferior.c:285: internal-error: inferior* find_inferior_pid(process_stratum_target*, int): Assertion `pid != 0' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) FAIL: gdb.threads/watchpoint-fork.exp: parent: singlethreaded: watchpoints work (GDB internal error)
The problem is that in remote_target::wait_as, we're hitting this:
switch (buf[0])
{
case 'E': /* Error of some sort. */
/* We're out of sync with the target now. Did it continue or
not? Not is more likely, so report a stop. */
rs->waiting_for_stop_reply = 0;
warning (_("Remote failure reply: %s"), buf);
status->kind = TARGET_WAITKIND_STOPPED;
status->value.sig = GDB_SIGNAL_0;
break;
which leaves event_ptid as null_ptid. At the end of the function, we then reach:
else if (status->kind != TARGET_WAITKIND_EXITED
&& status->kind != TARGET_WAITKIND_SIGNALLED)
{
if (event_ptid != null_ptid)
record_currthread (rs, event_ptid);
else
event_ptid = inferior_ptid; <<<<< here
}
and the trouble is that with the multi-target patch, we'll get here
with inferior_ptid as null_ptid too. That is done exactly to find
these implicit assumptions that inferior_ptid is a good choice for
default thread, which isn't generaly true.
I first thought of fixing this in the "case 'E'" path, but, given that
this "event_ptid = inferior_ptid" path is also taken when the remote
target does not support threads at all, no thread-related packets or
extensions, it's better to fix it in latter path, to handle all
scenarios that miss reporting a thread.
That's what this patch does.
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* remote.c (first_remote_resumed_thread): New.
(remote_target::wait_as): Use it as default event_ptid instead of
inferior_ptid.
I believe the tail end of remote_target::mourn_inferior is broken, and
it's been broken for too long to even bother trying to fix. Most
probably nobody needs it. If the code is reached and we find the
target is running, we'd need to resync the thread list, at least,
since generic_mourn_inferior got rid of all the threads in the
inferior, otherwise, we'd hit an assertion on the next call to
inferior_thread(), for example. A "correct" fix would probably
involve restarting the whole remote_target::start_remote requence,
exactly as if we had completely disconnected and reconnected from
scratch.
Note that regular stub debugging usually uses plain target remote, but
this code is only reachable in target extended-mode:
- The !remote_multi_process_p check means that it's only reacheable if
the stub does not support multi-process. I.e., there can only ever
be one live process.
- remote_target::mourn_inferior has this at the top:
/* In 'target remote' mode with one inferior, we close the connection. */
if (!rs->extended && number_of_live_inferiors () <= 1)
{
unpush_target (this);
/* remote_close takes care of doing most of the clean up. */
generic_mourn_inferior ();
return;
}
Which means that if we only had one live inferior (which for our
case, must be true), we'll have closed the connection already,
unless we're in extended-remote mode.
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* remote.c (remote_target::mourn_inferior): No longer check
whether the target is running.
The "set remote exec-file" setting is per-inferior, but the "show
remote exec-file" command always shows the last set exec-file,
irrespective of the current inferior. E.g.:
# Set inferior 1's exec-file:
(gdb) set remote exec-file prog1
# Add inferior 2, switch to it, and set its exec-file:
(gdb) add-inferior
Added inferior 2
(gdb) inferior 2
(gdb) set remote exec-file prog2
# Switch back to inferior 1, and show its exec-file:
(gdb) inferior 1
(gdb) show remote exec-file
prog2
^^^^^ should show "prog1" instead here.
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* remote.c (show_remote_exec_file): Show the current inferior's
exec-file instead of the command variable's value.
gdb/testsuite/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* gdb.base/remote-exec-file.exp: New file.
I noticed that get_exec_file could return a "const char *". This
patch implements this change.
I couldn't build all the code -- but I did build Linux native and a
mingw cross.
Consequently, the NTO code has a hack, where it casts away const. I
think this can be removed, but that required more work there, and
since I couldn't compile it, I felt it best not to try.
Let me know what you think.
gdb/ChangeLog
2019-12-16 Tom Tromey <tromey@adacore.com>
* windows-nat.c (windows_nat_target::attach): Update.
* remote.c (extended_remote_target::attach): Update.
* procfs.c (procfs_target::attach): Update.
* nto-procfs.c (nto_procfs_target::attach): Update.
(nto_procfs_target::create_inferior): Update.
* inf-ptrace.c (inf_ptrace_target::attach): Update.
* gnu-nat.c (gnu_nat_target::attach): Update.
(gnu_nat_target::detach): Update.
* darwin-nat.c (darwin_nat_target::attach): Update.
* corefile.c (get_exec_file): Constify result. Remove extraneous
return.
* bsd-kvm.c (bsd_kvm_target_open): Update.
* gdbsupport/common-inferior.h (get_exec_file): Constify result.
gdb/gdbserver/ChangeLog
2019-12-16 Tom Tromey <tromey@adacore.com>
* server.c (get_exec_file): Constify result.
Change-Id: I29c60f7313a7def0dcb290ff0c2a4c1dea4f981f
While debugging, i felt the need to adjust the truncation length of remote
packets so i could see more or less data as needed. The default is currently
set to 512 bytes.
This patch makes this option adjustable through the new "set debug
remote-packet-max-chars" command. It can be set to unlimited if we want to
completely disable truncation.
Update on v5:
- Adjusted function and variable documentation, NEWS entry and GDB manual.
gdb/ChangeLog:
2019-11-25 Luis Machado <luis.machado@linaro.org>
* NEWS (New Commands): Mention "set debug remote-packet-max-chars".
* remote.c (REMOTE_DEBUG_MAX_CHAR): Remove.
(remote_packet_max_chars): New static global.
(show_remote_packet_max_chars): New function.
(remote_target::putpkt_binary): Adjust to use new
remote_packet_max_chars option.
(remote_target::getpkt_or_notif_sane_1): Likewise.
(_initialize_remote): Register new remote-packet-max-chars option.
gdb/doc/ChangeLog:
2019-11-25 Luis Machado <luis.machado@linaro.org>
* gdb.texinfo (Debugging Output): Document set debug
remote-packet-max-chars.
Change-Id: I2e871b37bfcaa6376537c3fe3db8f016dd806a7c
Simon Marchi