DolphinQt: Properly lock CPU before accessing emulated memory

This fixes a problem I was having where using frame advance with the
debugger open would frequently cause panic alerts about invalid addresses
due to the CPU thread changing MSR.DR while the host thread was trying
to access memory.

To aid in tracking down all the places where we weren't properly locking
the CPU, I've created a new type (in Core.h) that you have to pass as a
reference or pointer to functions that require running as the CPU thread.

1 files changed, 46 insertions, 36 deletions

diff --git a/Source/Core/DolphinQt/Debugger/ThreadWidget.cpp b/Source/Core/DolphinQt/Debugger/ThreadWidget.cpp
index 07fb8eadef..c9d0df2930 100644
--- a/Source/Core/DolphinQt/Debugger/ThreadWidget.cpp
+++ b/Source/Core/DolphinQt/Debugger/ThreadWidget.cpp
@@ -256,7 +256,9 @@ void ThreadWidget::Update()
   {
     m_thread_table->setRowCount(0);
     UpdateThreadContext({});
-    UpdateThreadCallstack({});
+
+    Core::CPUThreadGuard guard;
+    UpdateThreadCallstack(guard, {});
   }
   if (emu_state != Core::State::Paused)
     return;
@@ -264,8 +266,8 @@ void ThreadWidget::Update()
   const auto format_hex = [](u32 value) {
     return QStringLiteral("%1").arg(value, 8, 16, QLatin1Char('0'));
   };
-  const auto format_hex_from = [&format_hex](u32 addr) {
-    addr = PowerPC::HostIsRAMAddress(addr) ? PowerPC::HostRead_U32(addr) : 0;
+  const auto format_hex_from = [&format_hex](const Core::CPUThreadGuard& guard, u32 addr) {
+    addr = PowerPC::HostIsRAMAddress(guard, addr) ? PowerPC::HostRead_U32(guard, addr) : 0;
     return format_hex(addr);
   };
   const auto get_state = [](u16 thread_state) {
@@ -298,35 +300,41 @@ void ThreadWidget::Update()
         .arg(start, 8, 16, QLatin1Char('0'));
   };
 
-  // YAGCD - Section 4.2.1.4 Dolphin OS Globals
-  m_current_context->setText(format_hex_from(0x800000D4));
-  m_current_thread->setText(format_hex_from(0x800000E4));
-  m_default_thread->setText(format_hex_from(0x800000D8));
+  {
+    Core::CPUThreadGuard guard;
+
+    // YAGCD - Section 4.2.1.4 Dolphin OS Globals
+    m_current_context->setText(format_hex_from(guard, 0x800000D4));
+    m_current_thread->setText(format_hex_from(guard, 0x800000E4));
+    m_default_thread->setText(format_hex_from(guard, 0x800000D8));
 
-  m_queue_head->setText(format_hex_from(0x800000DC));
-  m_queue_tail->setText(format_hex_from(0x800000E0));
+    m_queue_head->setText(format_hex_from(guard, 0x800000DC));
+    m_queue_tail->setText(format_hex_from(guard, 0x800000E0));
 
-  // Thread group
-  m_threads = PowerPC::debug_interface.GetThreads();
-  int i = 0;
-  m_thread_table->setRowCount(i);
-  for (const auto& thread : m_threads)
-  {
-    m_thread_table->insertRow(i);
-    m_thread_table->setItem(i, 0, new QTableWidgetItem(format_hex(thread->GetAddress())));
-    m_thread_table->setItem(i, 1, new QTableWidgetItem(get_state(thread->GetState())));
-    m_thread_table->setItem(i, 2, new QTableWidgetItem(QString::number(thread->IsDetached())));
-    m_thread_table->setItem(i, 3, new QTableWidgetItem(QString::number(thread->IsSuspended())));
-    m_thread_table->setItem(i, 4,
-                            new QTableWidgetItem(get_priority(thread->GetBasePriority(),
-                                                              thread->GetEffectivePriority())));
-    m_thread_table->setItem(
-        i, 5, new QTableWidgetItem(get_stack(thread->GetStackEnd(), thread->GetStackStart())));
-    m_thread_table->setItem(i, 6, new QTableWidgetItem(QString::number(thread->GetErrno())));
-    m_thread_table->setItem(i, 7,
-                            new QTableWidgetItem(QString::fromStdString(thread->GetSpecific())));
-    i += 1;
+    // Thread group
+    m_threads = PowerPC::debug_interface.GetThreads(guard);
+
+    int i = 0;
+    m_thread_table->setRowCount(i);
+    for (const auto& thread : m_threads)
+    {
+      m_thread_table->insertRow(i);
+      m_thread_table->setItem(i, 0, new QTableWidgetItem(format_hex(thread->GetAddress())));
+      m_thread_table->setItem(i, 1, new QTableWidgetItem(get_state(thread->GetState())));
+      m_thread_table->setItem(i, 2, new QTableWidgetItem(QString::number(thread->IsDetached())));
+      m_thread_table->setItem(i, 3, new QTableWidgetItem(QString::number(thread->IsSuspended())));
+      m_thread_table->setItem(i, 4,
+                              new QTableWidgetItem(get_priority(thread->GetBasePriority(),
+                                                                thread->GetEffectivePriority())));
+      m_thread_table->setItem(
+          i, 5, new QTableWidgetItem(get_stack(thread->GetStackEnd(), thread->GetStackStart())));
+      m_thread_table->setItem(i, 6, new QTableWidgetItem(QString::number(thread->GetErrno())));
+      m_thread_table->setItem(
+          i, 7, new QTableWidgetItem(QString::fromStdString(thread->GetSpecific(guard))));
+      i += 1;
+    }
   }
+
   m_thread_table->resizeColumnsToContents();
   m_thread_table->resizeRowsToContents();
 
@@ -425,7 +433,8 @@ void ThreadWidget::UpdateThreadContext(const Common::Debug::PartialContext& cont
   m_context_table->resizeColumnsToContents();
 }
 
-void ThreadWidget::UpdateThreadCallstack(const Common::Debug::PartialContext& context)
+void ThreadWidget::UpdateThreadCallstack(const Core::CPUThreadGuard& guard,
+                                         const Common::Debug::PartialContext& context)
 {
   m_callstack_table->setRowCount(0);
 
@@ -439,13 +448,13 @@ void ThreadWidget::UpdateThreadCallstack(const Common::Debug::PartialContext& co
   u32 sp = context.gpr->at(1);
   for (int i = 0; i < 16; i++)
   {
-    if (sp == 0 || sp == 0xffffffff || !PowerPC::HostIsRAMAddress(sp))
+    if (sp == 0 || sp == 0xffffffff || !PowerPC::HostIsRAMAddress(guard, sp))
       break;
     m_callstack_table->insertRow(i);
     m_callstack_table->setItem(i, 0, new QTableWidgetItem(format_hex(sp)));
-    if (PowerPC::HostIsRAMAddress(sp + 4))
+    if (PowerPC::HostIsRAMAddress(guard, sp + 4))
     {
-      const u32 lr_save = PowerPC::HostRead_U32(sp + 4);
+      const u32 lr_save = PowerPC::HostRead_U32(guard, sp + 4);
       m_callstack_table->setItem(i, 2, new QTableWidgetItem(format_hex(lr_save)));
       m_callstack_table->setItem(i, 3,
                                  new QTableWidgetItem(QString::fromStdString(
@@ -455,18 +464,19 @@ void ThreadWidget::UpdateThreadCallstack(const Common::Debug::PartialContext& co
     {
       m_callstack_table->setItem(i, 2, new QTableWidgetItem(QStringLiteral("--------")));
     }
-    sp = PowerPC::HostRead_U32(sp);
+    sp = PowerPC::HostRead_U32(guard, sp);
     m_callstack_table->setItem(i, 1, new QTableWidgetItem(format_hex(sp)));
   }
 }
 
 void ThreadWidget::OnSelectionChanged(int row)
 {
+  Core::CPUThreadGuard guard;
   Common::Debug::PartialContext context;
 
   if (row >= 0 && size_t(row) < m_threads.size())
-    context = m_threads[row]->GetContext();
+    context = m_threads[row]->GetContext(guard);
 
   UpdateThreadContext(context);
-  UpdateThreadCallstack(context);
+  UpdateThreadCallstack(guard, context);
 }