[20/34] Windows gdbserver: Eliminate soft-interrupt mechanism
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Commit Message
I noticed that faked_breakpoint is write only. And then I hacked
win32_process_target::request_interrupt to force it to stop threads
using the soft_interrupt_requested mechanism (which suspends threads,
and then fakes a breakpoint event in the main thread), and saw that it
no longer works -- gdbserver crashes accessing a NULL current_thread,
because fake_breakpoint_event does not switch to a thread.
This code was originally added for Windows CE, as neither
GenerateConsoleCtrlEvent nor DebugBreakProcess worked there.
We nowadays require Windows XP or later, and XP has DebugBreakProcess.
The soft_interrupt_requested mechanism has other problems, like for
example faking the event in the main thread, even if that thread was
previously stopped, due to scheduler-locking.
A following patch will add a similar mechanism stopping all threads
with SuspendThread to native GDB, for non-stop mode, which doesn't
have these problems. It's different enough from this old code that I
think we should just rip the old code out, and reimplement it from
scratch (based on gdb's version) when we need it.
Change-Id: I89e98233a9c40c6dcba7c8e1dacee08603843fb1
---
gdbserver/win32-low.cc | 32 +-------------------------------
gdbserver/win32-low.h | 8 --------
2 files changed, 1 insertion(+), 39 deletions(-)
Comments
>>>>> "Pedro" == Pedro Alves <pedro@palves.net> writes:
Pedro> A following patch will add a similar mechanism stopping all threads
Pedro> with SuspendThread to native GDB, for non-stop mode, which doesn't
Pedro> have these problems. It's different enough from this old code that I
Pedro> think we should just rip the old code out, and reimplement it from
Pedro> scratch (based on gdb's version) when we need it.
Thank you.
Approved-By: Tom Tromey <tom@tromey.com>
Tom
@@ -307,8 +307,6 @@ do_initial_child_stuff (HANDLE proch, DWORD pid, int attached)
windows_process.process_id = pid;
windows_process.main_thread_id = 0;
- windows_process.soft_interrupt_requested = 0;
- windows_process.faked_breakpoint = 0;
windows_process.open_process_used = true;
memset (&windows_process.current_event, 0,
@@ -433,7 +431,6 @@ child_continue_for_kill (DWORD continue_status, int thread_id)
{
continue_one_thread (thread, thread_id);
});
- windows_process.faked_breakpoint = 0;
return continue_last_debug_event (continue_status, debug_threads);
}
@@ -941,23 +938,6 @@ suspend_one_thread (thread_info *thread)
th->suspend ();
}
-static void
-fake_breakpoint_event (void)
-{
- OUTMSG2(("fake_breakpoint_event\n"));
-
- windows_process.faked_breakpoint = 1;
-
- memset (&windows_process.current_event, 0,
- sizeof (windows_process.current_event));
- windows_process.current_event.dwThreadId = windows_process.main_thread_id;
- windows_process.current_event.dwDebugEventCode = EXCEPTION_DEBUG_EVENT;
- windows_process.current_event.u.Exception.ExceptionRecord.ExceptionCode
- = EXCEPTION_BREAKPOINT;
-
- for_each_thread (suspend_one_thread);
-}
-
/* See nat/windows-nat.h. */
bool
@@ -1012,13 +992,6 @@ get_child_debug_event (DWORD *continue_status,
DEBUG_EVENT *current_event = &windows_process.current_event;
- if (windows_process.soft_interrupt_requested)
- {
- windows_process.soft_interrupt_requested = 0;
- fake_breakpoint_event ();
- goto gotevent;
- }
-
windows_process.attaching = 0;
{
for (thread_info *thread : all_threads)
@@ -1058,8 +1031,6 @@ get_child_debug_event (DWORD *continue_status,
}
}
- gotevent:
-
switch (current_event->dwDebugEventCode)
{
case CREATE_THREAD_DEBUG_EVENT:
@@ -1313,8 +1284,7 @@ win32_process_target::request_interrupt ()
if (DebugBreakProcess (windows_process.handle))
return;
- /* Last resort, suspend all threads manually. */
- windows_process.soft_interrupt_requested = 1;
+ OUTMSG2 (("Could not interrupt.\n"));
}
bool
@@ -187,14 +187,6 @@ struct gdbserver_windows_process : public windows_nat::windows_process_info
debug event off the win32 API. */
struct target_waitstatus cached_status;
- /* Non zero if an interrupt request is to be satisfied by suspending
- all threads. */
- int soft_interrupt_requested = 0;
-
- /* Non zero if the inferior is stopped in a simulated breakpoint done
- by suspending all the threads. */
- int faked_breakpoint = 0;
-
/* True if current_process_handle needs to be closed. */
bool open_process_used = false;