Writing to inferior_ptid in
windows_nat_target::get_windows_debug_event is just incorrect and not
necessary. We'll report the event to GDB's core, which then takes
care of switching inferior_ptid / current thread.
Related (see windows_nat_target::get_windows_debug_event), there's
also a "current_windows_thread" global that is just begging to get out
of sync with core GDB's current thread. This patch removes it.
gdbserver already does not have an equivalent global in win32-low.cc.
gdb/ChangeLog:
2020-06-18 Pedro Alves <palves@redhat.com>
* nat/windows-nat.c (current_windows_thread): Remove.
* nat/windows-nat.h (current_windows_thread): Remove.
* windows-nat.c (windows_nat_target::stopped_by_sw_breakpoint):
Adjust.
(display_selectors): Adjust to fetch the current
windows_thread_info based on inferior_ptid.
(fake_create_process): No longer write to current_windows_thread.
(windows_nat_target::get_windows_debug_event):
Don't set inferior_ptid or current_windows_thread.
(windows_nat_target::wait): Adjust to not rely on
current_windows_thread.
(do_initial_windows_stuff): Now a method of windows_nat_target.
Switch to the last_ptid thread.
(windows_nat_target::attach): Adjust.
(windows_nat_target::detach): Use switch_to_no_thread instead of
writing to inferior_ptid directly.
(windows_nat_target::create_inferior): Adjust.
I sometimes encountered a weird breakpoint failure when using start:
(gdb) start
Temporary breakpoint 2 at 0x40162d: file gdb-25911.c, line 4.
Starting program: C:\src\tests\gdb-25911.exe
Warning:
Cannot insert breakpoint 2.
Cannot access memory at address 0x401628
After trying a lot of combinations, I found a way to reproduce it:
(gdb) file gdb-25987.exe
Reading symbols from gdb-25987.exe...
(gdb) start
Temporary breakpoint 1 at 0x401638: file gdb-25987.cpp, line 13.
Starting program: C:\src\tests\gdb-25987.exe
Temporary breakpoint 1, main () at gdb-25987.cpp:13
13 int main() {
(gdb) c
Continuing.
Program received signal SIGSEGV, Segmentation fault.
MyClass::call (this=0x3d20d0) at gdb-25987.cpp:8
8 *(char*)(nullptr) = 1;
(gdb) kill
Kill the program being debugged? (y or n) y
[Inferior 1 (process 1140) killed]
(gdb) file gdb-25911.exe
Load new symbol table from "gdb-25911.exe"? (y or n) y
Reading symbols from gdb-25911.exe...
(gdb) start
Temporary breakpoint 2 at 0x40162d: file gdb-25911.c, line 4.
Starting program: C:\src\tests\gdb-25911.exe
Warning:
Cannot insert breakpoint 2.
Cannot access memory at address 0x401628
Command aborted.
The actual failure was that ReadProcessMemory used a process handle that
was no longer valid.
And the underlying reason was that the windows_thread_info destructor
closes a thread handle that was provided earlier by WaitForDebugEvent.
But since this is not allowed (and it was actually already closed at this
point, and the handle value reused), this closed another still-needed handle.
gdb/ChangeLog:
2020-05-27 Hannes Domani <ssbssa@yahoo.de>
* nat/windows-nat.c (windows_thread_info::~windows_thread_info):
Don't close thread handle.
Simon pointed out that the windows-nat sharing series broke the Cygwin
build. This patch fixes the problem, by moving the Cygwin-specific
code to a new handler function. This approach is taken because this
code calls find_pc_partial_function, which isn't available in
gdbserver.
gdb/ChangeLog
2020-04-16 Tom Tromey <tromey@adacore.com>
* windows-nat.c (windows_nat::handle_access_violation): New
function.
* nat/windows-nat.h (handle_access_violation): Declare.
* nat/windows-nat.c (handle_exception): Move Cygwin code to
windows-nat.c. Call handle_access_violation.
gdbserver/ChangeLog
2020-04-16 Tom Tromey <tromey@adacore.com>
* win32-low.cc (windows_nat::handle_access_violation): New
function.
The new code regarding pending stops only checks for EXCEPTION_BREAKPOINT,
but for WOW64 processes STATUS_WX86_BREAKPOINT is necessary as well.
Also, ignore_first_breakpoint is used now in nat/windows-nat.c as well,
but was not available there.
gdb/ChangeLog:
2020-04-10 Hannes Domani <ssbssa@yahoo.de>
* nat/windows-nat.c (STATUS_WX86_BREAKPOINT, STATUS_WX86_SINGLE_STEP):
Move to...
* nat/windows-nat.h (STATUS_WX86_BREAKPOINT, STATUS_WX86_SINGLE_STEP):
... here.
* windows-nat.c (windows_nat_target::get_windows_debug_event):
Check for STATUS_WX86_BREAKPOINT.
(windows_nat_target::wait): Same.
Now that last_wait_event is entirely handled in nat/windows-nat.c, it
can be made static.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* nat/windows-nat.h (last_wait_event): Don't declare.
(wait_for_debug_event): Update comment.
* nat/windows-nat.c (last_wait_event): Now static.
This moves the wait_for_debug_event helper function to
nat/windows-nat.c, and changes gdbserver to use it.
wait_for_debug_event is a wrapper for WaitForDebugEvent that also sets
last_wait_event when appropriate. This is needed to properly handle
queued stops.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* windows-nat.c (wait_for_debug_event): Move to
nat/windows-nat.c.
* nat/windows-nat.h (wait_for_debug_event): Declare.
* nat/windows-nat.c (wait_for_debug_event): Move from
windows-nat.c. No longer static.
gdbserver/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* win32-low.c (win32_kill, get_child_debug_event): Use
wait_for_debug_event.
This introduces a new "fetch_pending_stop" function and changes gdb to
use it. This function removes the first matching pending stop from
the list of such stops.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* windows-nat.c (get_windows_debug_event): Use
fetch_pending_stop.
* nat/windows-nat.h (fetch_pending_stop): Declare.
* nat/windows-nat.c (fetch_pending_stop): New function.
This adds a couple of functions to nat/windows-nat.c and changes gdb
and gdbserver to use them. One function checks the list of pending
stops for a match (not yet used by gdbserver, but will be in a
subsequent patch); and the other is a wrapper for ContinueDebugEvent
that always uses the last "real" stop event.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* windows-nat.c (windows_continue): Use matching_pending_stop and
continue_last_debug_event.
* nat/windows-nat.h (matching_pending_stop)
(continue_last_debug_event): Declare.
* nat/windows-nat.c (DEBUG_EVENTS): New define.
(matching_pending_stop, continue_last_debug_event): New
functions.
gdbserver/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* win32-low.c (child_continue): Call continue_last_debug_event.
Both gdb and gdbserver have a "handle_exception" function, the bulk of
which is shared between the two implementations. This patch arranges
for the entire thing to be moved into nat/windows-nat.c, with the
differences handled by callbacks. This patch introduces one more
callback to make this possible.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* windows-nat.c (MS_VC_EXCEPTION): Move to nat/windows-nat.c.
(handle_exception_result): Move to nat/windows-nat.h.
(DEBUG_EXCEPTION_SIMPLE): Remove.
(windows_nat::handle_ms_vc_exception): New function.
(handle_exception): Move to nat/windows-nat.c.
(get_windows_debug_event): Update.
(STATUS_WX86_BREAKPOINT, STATUS_WX86_SINGLE_STEP): Move to
nat/windows-nat.c.
* nat/windows-nat.h (handle_ms_vc_exception): Declare.
(handle_exception_result): Move from windows-nat.c.
(handle_exception): Declare.
* nat/windows-nat.c (MS_VC_EXCEPTION, handle_exception)
(STATUS_WX86_SINGLE_STEP, STATUS_WX86_BREAKPOINT): Move from
windows-nat.c.
gdbserver/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* win32-low.c (handle_exception): Remove.
(windows_nat::handle_ms_vc_exception): New function.
(get_child_debug_event): Add "continue_status" parameter.
Update.
(win32_wait): Update.
This moves get_image_name to nat/windows-nat.c so that it can be
shared between gdb and gdbserver.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* windows-nat.c (get_image_name): Move to nat/windows-nat.c.
(handle_load_dll): Update.
* nat/windows-nat.c (get_image_name): Move from windows-nat.c.
gdbserver/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* win32-low.c (get_image_name): Remove.
(handle_load_dll): Update.
PR gdb/22992 concerns an assertion failure in gdb when debugging a
certain inferior:
int finish_step_over(execution_control_state*): Assertion `ecs->event_thread->control.trap_expected' failed.
Initially the investigation centered on the discovery that gdb was not
suspending other threads when attempting to single-step. This
oversight is corrected in this patch: now, when stepping a thread, gdb
will call SuspendThread on all other threads.
However, the bug persisted even after this change. In particular,
WaitForDebugEvent could see a stop for a thread that was ostensibly
suspended. Our theory of what is happening here is that there are
actually simultaneous breakpoint hits, and the Windows kernel queues
the events, causing the second stop to be reported on a suspended
thread.
In Windows 10 or later gdb could use the DBG_REPLY_LATER flag to
ContinueDebugEvent to request that such events be re-reported later.
However, relying on that did not seem advisable, so this patch instead
arranges to queue such "pending" stops, and then to report them later,
once the step has completed.
In the PR, Pedro pointed out that it's best in this scenario to
implement the stopped_by_sw_breakpoint method, so this patch does this
as well.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
PR gdb/22992
* windows-nat.c (current_event): Update comment.
(last_wait_event, desired_stop_thread_id): New globals.
(struct pending_stop): New.
(pending_stops): New global.
(windows_nat_target) <stopped_by_sw_breakpoint>
<supports_stopped_by_sw_breakpoint>: New methods.
(windows_fetch_one_register): Add assertions. Adjust PC.
(windows_continue): Handle pending stops. Suspend other threads
when stepping. Use last_wait_event
(wait_for_debug_event): New function.
(get_windows_debug_event): Use wait_for_debug_event. Handle
pending stops. Queue spurious stops.
(windows_nat_target::wait): Set stopped_at_software_breakpoint.
(windows_nat_target::kill): Use wait_for_debug_event.
* nat/windows-nat.h (struct windows_thread_info)
<stopped_at_software_breakpoint>: New field.
* nat/windows-nat.c (windows_thread_info::resume): Clear
stopped_at_software_breakpoint.
This adds "suspend" and "resume" methods to windows_thread_info, and
changes gdb and gdbserver to share this code.
gdb/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* windows-nat.c (thread_rec): Use windows_thread_info::suspend.
(windows_continue): Use windows_continue::resume.
* nat/windows-nat.h (struct windows_thread_info) <suspend,
resume>: Declare new methods.
* nat/windows-nat.c: New file.
* configure.nat (NATDEPFILES): Add nat/windows-nat.o when needed.
gdbserver/ChangeLog
2020-04-08 Tom Tromey <tromey@adacore.com>
* win32-low.c (win32_require_context, suspend_one_thread): Use
windows_thread_info::suspend.
(continue_one_thread): Use windows_thread_info::resume.
* configure.srv (srv_tgtobj): Add windows-nat.o when needed.
