Add step-in and GUI support for the GDB stub

src/frontends/qriscv/debug_session.cc

@@ -11,6 +11,7 @@
 #include <QAction>
 #include <QMessageBox>
 #include <QTimer>
+#include<unistd.h>
 
 #include "qriscv/application.h"
 #include "uriscv/error.h"
@@ -52,6 +53,19 @@ void DebugSession::halt() {
   setStatus(MS_HALTED);
 }
 
+void DebugSession::killServer(){
+  if(isGdbEnabled()){
+    int w = 0;
+    w = gdb->killServer();
+    while(w != 1){
+        //wait till the server correctly shutdown 
+      }
+    printf("gdb server terminated\n");
+
+    gdb->~GDBServer();
+   }
+}
+
 void DebugSession::setSpeed(int value) {
   value = qBound(0, value, kMaxSpeed);
   if (speed != value) {
@@ -70,6 +84,10 @@ void DebugSession::setStopMask(unsigned int value) {
     machine->setStopMask(stopMask);
 }
 
+void DebugSession::setGdbStatus(bool newStatus){
+  GdbStatus = newStatus;
+}
+
 void DebugSession::createActions() {
   startMachineAction = new QAction("Power On", this);
   startMachineAction->setShortcut(QKeySequence("F5"));
@@ -174,6 +192,12 @@ void DebugSession::initializeMachine() {
 
   try {
     machine.reset(new Machine(config, &breakpoints, &suspects, &tracepoints));
+    if (isGdbEnabled()) {
+      gts = std::thread([&]() {
+            gdb = new GDBServer(machine.get());
+            gdb->StartServer(); });
+      gts.detach();
+    }
   } catch (const FileError &e) {
     QMessageBox::critical(
         Appl()->getApplWindow(),
@@ -266,6 +290,7 @@ void DebugSession::startMachine() {
 
 void DebugSession::onHaltMachine() {
   assert(status != MS_HALTED);
+  killServer();
   halt();
 }
 
@@ -282,6 +307,9 @@ void DebugSession::onResetMachine() {
   stop();
 
   machine.reset();
+
+  killServer();
+
   initializeMachine();
   if (machine) {
     Q_EMIT MachineReset();
@@ -443,4 +471,4 @@ void DebugSession::relocateStoppoints(const SymbolTable *newTable,
   }
 
   set = rset;
-}
+}

src/frontends/qriscv/monitor_window.cc

@@ -11,6 +11,8 @@
 
 #include <QtWidgets>
 
+#include "gdb/gdb.h"
+
 #include "uriscv/device.h"
 #include "uriscv/error.h"
 #include "uriscv/machine.h"
@@ -173,6 +175,13 @@ void MonitorWindow::createActions() {
   removeTraceAction = new QAction("Remove Traced Region", this);
   removeTraceAction->setEnabled(false);
 
+  //GDB server 
+  enableGDBserver = new QAction("Enable GDB Server", this);
+  enableGDBserver->setCheckable(true);
+  enableGDBserver->setChecked(debugSession->isGdbEnabled());
+  connect(enableGDBserver, SIGNAL(triggered()),this, SLOT(onEnableGDBserver())); 
+  enableGDBserver->setEnabled(true);
+
   speedActionGroup = new QActionGroup(this);
   for (int i = 0; i < DebugSession::kNumSpeedLevels; i++) {
     simSpeedActions[i] = new QAction(simSpeedMnemonics[i], speedActionGroup);
@@ -279,6 +288,10 @@ void MonitorWindow::createMenu() {
     stopMaskSubMenu->addAction(it->second);
   }
 
+  debugMenu->addSeparator();
+  QMenu *gdbMenu = debugMenu->addMenu("GDB Server");
+  gdbMenu->addAction(enableGDBserver); //power one the server
+
   QMenu *settingsMenu = menuBar()->addMenu("Se&ttings");
   QMenu *speedLevelsSubMenu = settingsMenu->addMenu("Simulation Speed");
   for (int i = 0; i < DebugSession::kNumSpeedLevels; i++)
@@ -797,6 +810,10 @@ void MonitorWindow::onAddTracepoint() {
                          "it overlaps with an already inserted range");
 }
 
+void MonitorWindow::onEnableGDBserver(){
+  dbgSession->setGdbStatus(!dbgSession->isGdbEnabled());
+}
+
 StatusDisplay::StatusDisplay(QWidget *parent) : QWidget(parent) {
   QHBoxLayout *layout = new QHBoxLayout(this);
   layout->setContentsMargins(0, 0, 0, 0);

src/gdb/gdb.cc

@@ -47,11 +47,31 @@ pthread_mutex_t stopped_mutex = PTHREAD_MUTEX_INITIALIZER;
 pthread_mutex_t bp_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 GDBServer::GDBServer(Machine *mac) {
-  this->killed = false;
   this->stopped = false;
   this->mac = mac;
 }
 
+GDBServer::~GDBServer() {
+  this->mac = NULL;
+}
+
+GDBServer *gdb = NULL;
+bool *killed_ptr = NULL;
+
+int GDBServer::killServer() {
+    pthread_mutex_lock(&stopped_mutex);
+    stopped = true;                       // stop the machine
+    pthread_mutex_unlock(&stopped_mutex);
+
+    pthread_mutex_lock(&continue_mutex);
+    killed = true; 
+    pthread_cond_signal(&continue_cond);  // wake up the waiting thread
+    pthread_mutex_unlock(&continue_mutex);
+
+    return 1;
+}
+
+
 inline std::string GDBServer::getMsg(const std::string &msg) {
   static std::regex reg(R"(.*\$(.*)#.*)");
   std::smatch matches;
@@ -238,6 +258,10 @@ std::string GDBServer::ReadData(const std::string &msg) {
     return OKReply;
   } else if (body.c_str()[0] == 'c') {
 
+    pthread_mutex_lock(&stopped_mutex);
+      stopped = false;
+    pthread_mutex_unlock(&stopped_mutex);
+
     pthread_mutex_lock(&continue_mutex);
     pthread_cond_signal(&continue_cond);
     pthread_mutex_unlock(&continue_mutex);
@@ -252,6 +276,9 @@ std::string GDBServer::ReadData(const std::string &msg) {
     uint addr = parseBreakpoint(body);
     addBreakpoint(addr);
     return OKReply;
+  } else if (body.c_str()[0] == 's'){
+    stepIn();
+    return OKReply;
   } else if (strcmp(body.c_str(), vContMsg) == 0) {
     /* Not supported */
     return emptyReply;
@@ -262,22 +289,22 @@ std::string GDBServer::ReadData(const std::string &msg) {
 
 void *MachineStep(void *vargp) {
 
-  GDBServer *gdb = (GDBServer *)vargp;
-
-  while (true) {
-
+  while (!(*killed_ptr)) {
     pthread_mutex_lock(&continue_mutex);
-    pthread_cond_wait(&continue_cond, &continue_mutex);
+    pthread_cond_wait(&continue_cond, &continue_mutex); 
     pthread_mutex_unlock(&continue_mutex);
 
+    if (*killed_ptr) {
+      break;  // Exit the loop if killed
+    }
     bool s = false;
     do {
       gdb->Step();
 
       pthread_mutex_lock(&stopped_mutex);
       s = gdb->IsStopped();
       pthread_mutex_unlock(&stopped_mutex);
-    } while (!gdb->CheckBreakpoint() && !s);
+    } while (!(*killed_ptr) && !gdb->CheckBreakpoint() && !s);
 
     if (!s) {
       pthread_mutex_lock(&stopped_mutex);
@@ -297,6 +324,14 @@ void GDBServer::sendMsg(const int &socket, const std::string &msg) {
   send(socket, reply.c_str(), (reply).size(), 0);
 }
 
+void GDBServer::stepIn(){
+  gdb->Step();
+
+  pthread_mutex_lock(&stopped_mutex);
+     gdb->Stop();
+  pthread_mutex_unlock(&stopped_mutex);
+}
+
 void GDBServer::StartServer() {
   DEBUGMSG("[GDB] Starting GDB Server\n");
 
@@ -305,6 +340,7 @@ void GDBServer::StartServer() {
   int opt = 1;
   int addrlen = sizeof(address);
   char buffer[1024] = {0};
+  this->killed = false;
 
   // Creating socket file descriptor
   if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
@@ -332,7 +368,9 @@ void GDBServer::StartServer() {
     exit(EXIT_FAILURE);
   }
 
-  for (;;) {
+    gdb = (GDBServer *)(this);
+
+    killed_ptr = &killed;
 
     pthread_t tid;
 
@@ -381,10 +419,9 @@ void GDBServer::StartServer() {
 
     pthread_kill(tid, SIGTERM);
 
-    // closing the connected socket
+    // clong the connected socket
     close(new_socket);
-  }
 
   // closing the listening socket
   shutdown(server_fd, SHUT_RDWR);
-}
+}

src/include/gdb/gdb.h

@@ -2,6 +2,9 @@
 //
 // SPDX-License-Identifier: GPL-3.0-or-later
 
+#ifndef GDB_SERVER_H
+#define GDB_SERVER_H
+
 #include "uriscv/machine.h"
 #include <cstring>
 #include <netinet/in.h>
@@ -16,6 +19,7 @@
 class GDBServer {
 public:
   GDBServer(Machine *mac);
+  ~GDBServer();
   void StartServer();
 
   static std::string GetChecksum(const std::string &msg) {
@@ -43,8 +47,11 @@ class GDBServer {
   inline void Stop() { stopped = true; };
   bool IsStopped() const { return stopped; };
 
+  int killServer() ;
+  bool isKilled() { return killed; };
+
 private:
-  bool killed, stopped;
+  bool killed = true, stopped;
   Machine *mac;
   std::vector<uint> breakpoints;
 
@@ -61,9 +68,13 @@ class GDBServer {
   inline void removeBreakpoint(const uint &addr);
 
   void sendMsg(const int &socket, const std::string &msg);
+
+  void stepIn();
 };
 
 typedef struct thread_arg_struct {
   GDBServer *gdb;
   int socket;
 } thread_arg_t;
+
+#endif // GDB_SERVER_H

src/include/qriscv/debug_session.h

@@ -6,13 +6,15 @@
 #define QRISCV_DEBUG_SESSION_H
 
 #include <QObject>
+#include <thread>
 
 #include "base/lang.h"
 #include "qriscv/cpu_status_map.h"
 #include "qriscv/stoppoint_list_model.h"
 #include "uriscv/machine.h"
 #include "uriscv/stoppoint.h"
 #include "uriscv/symbol_table.h"
+#include "gdb/gdb.h"
 
 enum MachineStatus { MS_HALTED, MS_RUNNING, MS_STOPPED };
 
@@ -40,6 +42,7 @@ class DebugSession : public QObject {
   bool isStarted() const { return status != MS_HALTED; }
 
   void halt();
+  void killServer();
 
   unsigned int getStopMask() const { return stopMask; }
   int getSpeed() const { return speed; }
@@ -66,6 +69,10 @@ class DebugSession : public QObject {
   QAction *debugStopAction;
   QAction *debugToggleAction;
 
+  //GDB stub
+  void setGdbStatus(bool value);
+  bool isGdbEnabled() { return GdbStatus; }
+
 public Q_SLOTS:
   void setStopMask(unsigned int value);
   void setSpeed(int value);
@@ -90,6 +97,8 @@ public Q_SLOTS:
 
   void initializeMachine();
 
+  void initializeThreadServer(MachineConfig*);
+
   void step(unsigned int steps);
   void runStepIteration();
   void runContIteration();
@@ -126,6 +135,10 @@ public Q_SLOTS:
 
   uint32_t idleSteps;
 
+  bool GdbStatus = false;
+  std::thread gts;
+  GDBServer *gdb;
+
 private Q_SLOTS:
   void onMachineConfigChanged();
 
@@ -143,4 +156,4 @@ private Q_SLOTS:
   void skip();
 };
 
-#endif // QRISCV_DEBUG_SESSION_H
+#endif // QRISCV_DEBUG_SESSION_H

src/include/qriscv/monitor_window.h

@@ -95,6 +95,8 @@ class MonitorWindow : public QMainWindow {
   QAction *addTraceAction;
   QAction *removeTraceAction;
 
+  QAction *enableGDBserver;
+
   QActionGroup *speedActionGroup;
   QAction *simSpeedActions[DebugSession::kNumSpeedLevels];
   static const char *const simSpeedMnemonics[DebugSession::kNumSpeedLevels];
@@ -159,6 +161,8 @@ private Q_SLOTS:
   void onAddSuspect();
   void onRemoveSuspect();
   void onAddTracepoint();
+
+  void onEnableGDBserver();
 };
 
 #endif // QRISCV_MONITOR_WINDOW_H