The current code suspends a thread just before calling
GetThreadContext. You can only call GetThreadContext if the thread is
suspended. But, after WaitForDebugEvent, all threads are implicitly
suspended. So I don't think we even needed to call SuspendThread
explictly at all before our GetThreadContext calls.
However, suspending threads when we're about to present a stop to gdb
simplifies adding non-stop support later. This way, the windows
SuspendThread state corresponds to whether a thread is suspended or
resumed from the core's perspective. Curiously, I noticed that Wine's
winedbg does something similar:
https://github.com/wine-mirror/wine/blob/234943344f7495d1e072338f0e06fa2d5cbf0aa1/programs/winedbg/gdbproxy.c#L651
This makes it much easier to reason about a thread's suspend state,
and simplifies adding non-stop mode later on.
Change-Id: Ifd6889a8afc041fad33cd1c4500e38941da6781b
---
gdb/windows-nat.c | 13 +++++--------
gdbserver/win32-low.cc | 5 +++++
2 files changed, 10 insertions(+), 8 deletions(-)
@@ -710,7 +710,6 @@ windows_nat_target::fetch_registers (struct regcache *regcache, int r)
{
if (th->wow64_context.ContextFlags == 0)
{
- th->suspend ();
th->wow64_context.ContextFlags = CONTEXT_DEBUGGER_DR;
CHECK (Wow64GetThreadContext (th->h, &th->wow64_context));
}
@@ -720,7 +719,6 @@ windows_nat_target::fetch_registers (struct regcache *regcache, int r)
{
if (th->context.ContextFlags == 0)
{
- th->suspend ();
th->context.ContextFlags = CONTEXT_DEBUGGER_DR;
CHECK (GetThreadContext (th->h, &th->context));
}
@@ -1320,12 +1318,6 @@ windows_nat_target::windows_continue (DWORD continue_status, int id,
}
th->resume ();
}
- else
- {
- /* When single-stepping a specific thread, other threads must
- be suspended. */
- th->suspend ();
- }
std::optional<unsigned> err;
do_synchronously ([&] ()
@@ -1816,6 +1808,11 @@ windows_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
th->stopped_at_software_breakpoint = true;
th->pc_adjusted = false;
}
+
+ /* All-stop, suspend all threads until they are
+ explicitly resumed. */
+ for (auto &thr : windows_process.thread_list)
+ thr->suspend ();
}
return result;
@@ -1226,6 +1226,11 @@ win32_process_target::wait (ptid_t ptid, target_waitstatus *ourstatus,
OUTMSG2 (("Child Stopped with signal = %d \n",
ourstatus->sig ()));
maybe_adjust_pc ();
+
+ /* All-stop, suspend all threads until they are explicitly
+ resumed. */
+ for_each_thread (suspend_one_thread);
+
return debug_event_ptid (&windows_process.current_event);
}
default: