Remote Non-Stop Support

 
Summary:
 
This patch is the beginnings of support for Non-stop mode in the remote protocol. Letting a user examine stopped threads, while other threads execute freely.

Non-stop mode is enabled using the setting target.non-stop-mode, which sends a QNonStop packet when establishing the remote connection.
Changes are also made to treat the '?' stop reply packet differently in non-stop mode, according to spec https://sourceware.org/gdb/current/onlinedocs/gdb/Remote-Non_002dStop.html#Remote-Non_002dStop.
A setting for querying the remote for default thread on setup is also included.

Handling of '%' async notification packets will be added next.

Reviewers: clayborg

Subscribers: lldb-commits, ADodds, ted, deepak2427

Differential Revision: http://reviews.llvm.org/D9656

llvm-svn: 237239

1 files changed, 56 insertions, 6 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 814b1ad1191..01c48d75822 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -391,7 +391,8 @@ ProcessGDBRemote::ProcessGDBRemote(Target& target, Listener &listener) :
     m_waiting_for_attach (false),
     m_destroy_tried_resuming (false),
     m_command_sp (),
-    m_breakpoint_pc_offset (0)
+    m_breakpoint_pc_offset (0),
+    m_initial_tid (LLDB_INVALID_THREAD_ID)
 {
     m_async_broadcaster.SetEventName (eBroadcastBitAsyncThreadShouldExit,   "async thread should exit");
     m_async_broadcaster.SetEventName (eBroadcastBitAsyncContinue,           "async thread continue");
@@ -769,8 +770,13 @@ ProcessGDBRemote::DoConnectRemote (Stream *strm, const char *remote_url)
         // We have a valid process
         SetID (pid);
         GetThreadList();
-        if (m_gdb_comm.SendPacketAndWaitForResponse("?", 1, m_last_stop_packet, false) == GDBRemoteCommunication::PacketResult::Success)
+        if (m_gdb_comm.GetStopReply(m_last_stop_packet))
         {
+
+            // '?' Packets must be handled differently in non-stop mode
+            if (GetTarget().GetNonStopModeEnabled())
+                HandleStopReplySequence();
+
             if (!m_target.GetArchitecture().IsValid()) 
             {
                 if (m_gdb_comm.GetProcessArchitecture().IsValid())
@@ -1052,8 +1058,13 @@ ProcessGDBRemote::DoLaunch (Module *exe_module, ProcessLaunchInfo &launch_info)
                 return error;
             }
 
-            if (m_gdb_comm.SendPacketAndWaitForResponse("?", 1, m_last_stop_packet, false) == GDBRemoteCommunication::PacketResult::Success)
+            if (m_gdb_comm.GetStopReply(m_last_stop_packet))
             {
+
+                // '?' Packets must be handled differently in non-stop mode
+                if (GetTarget().GetNonStopModeEnabled())
+                    HandleStopReplySequence();
+
                 const ArchSpec &process_arch = m_gdb_comm.GetProcessArchitecture();
 
                 if (process_arch.IsValid())
@@ -1153,12 +1164,22 @@ ProcessGDBRemote::ConnectToDebugserver (const char *connect_url)
             error.SetErrorString("not connected to remote gdb server");
         return error;
     }
+
+    // Send $QNonStop:1 packet on startup if required
+    if (GetTarget().GetNonStopModeEnabled())
+        m_gdb_comm.SetNonStopMode(true);
+
     m_gdb_comm.GetThreadSuffixSupported ();
     m_gdb_comm.GetListThreadsInStopReplySupported ();
     m_gdb_comm.GetHostInfo ();
     m_gdb_comm.GetVContSupported ('c');
     m_gdb_comm.GetVAttachOrWaitSupported();
-    
+
+    // Ask the remote server for the default thread id
+    if (GetTarget().GetNonStopModeEnabled())
+        m_gdb_comm.GetDefaultThreadId(m_initial_tid);
+
+
     size_t num_cmds = GetExtraStartupCommands().GetArgumentCount();
     for (size_t idx = 0; idx < num_cmds; idx++)
     {
@@ -1430,11 +1451,12 @@ ProcessGDBRemote::DoResume ()
         bool continue_packet_error = false;
         if (m_gdb_comm.HasAnyVContSupport ())
         {
-            if (m_continue_c_tids.size() == num_threads ||
+            if (!GetTarget().GetNonStopModeEnabled() &&
+                (m_continue_c_tids.size() == num_threads ||
                 (m_continue_c_tids.empty() &&
                  m_continue_C_tids.empty() &&
                  m_continue_s_tids.empty() &&
-                 m_continue_S_tids.empty()))
+                 m_continue_S_tids.empty())))
             {
                 // All threads are continuing, just send a "c" packet
                 continue_packet.PutCString ("c");
@@ -1662,6 +1684,27 @@ ProcessGDBRemote::DoResume ()
 }
 
 void
+ProcessGDBRemote::HandleStopReplySequence ()
+{
+    while(true)
+    {
+        // Send vStopped
+        StringExtractorGDBRemote response;
+        m_gdb_comm.SendPacketAndWaitForResponse("vStopped", response, false);
+
+        // OK represents end of signal list
+        if (response.IsOKResponse())
+            break;
+
+        // If not OK or a normal packet we have a problem
+        if (!response.IsNormalResponse())
+            break;
+
+        SetLastStopPacket(response);
+    }
+}
+
+void
 ProcessGDBRemote::ClearThreadIDList ()
 {
     Mutex::Locker locker(m_thread_list_real.GetMutex());
@@ -2095,6 +2138,13 @@ ProcessGDBRemote::RefreshStateAfterStop ()
         UpdateThreadIDList();
     }
 
+    // If we have queried for a default thread id
+    if (m_initial_tid != LLDB_INVALID_THREAD_ID)
+    {
+        m_thread_list.SetSelectedThreadByID(m_initial_tid);
+        m_initial_tid = LLDB_INVALID_THREAD_ID;
+    }
+
     // Let all threads recover from stopping and do any clean up based
     // on the previous thread state (if any).
     m_thread_list_real.RefreshStateAfterStop();