Kernel/HLE: Use a mutex to synchronize access to the HLE kernel state between the cpu thread and any other possible threads that might touch the kernel (network thread, etc).

This mutex is acquired in SVC::CallSVC, ie, as soon as the guest application enters the HLE kernel, and should be acquired by the aforementioned threads before modifying kernel structures.

src/core/CMakeLists.txt

@@ -60,6 +60,7 @@ set(SRCS
             hle/kernel/timer.cpp
             hle/kernel/vm_manager.cpp
             hle/kernel/wait_object.cpp
+            hle/lock.cpp
             hle/romfs.cpp
             hle/service/ac/ac.cpp
             hle/service/ac/ac_i.cpp
@@ -258,6 +259,7 @@ set(HEADERS
             hle/kernel/timer.h
             hle/kernel/vm_manager.h
             hle/kernel/wait_object.h
+            hle/lock.h
             hle/result.h
             hle/romfs.h
             hle/service/ac/ac.h

src/core/hle/kernel/kernel.h

@@ -129,4 +129,4 @@ void Init(u32 system_mode);
 /// Shutdown the kernel
 void Shutdown();
 
-} // namespace
+} // namespace Kernel

src/core/hle/lock.cpp

@@ -0,0 +1,11 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <core/hle/lock.h>
+
+namespace HLE {
+std::mutex g_hle_lock;
+}

src/core/hle/lock.h

@@ -0,0 +1,18 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <mutex>
+
+namespace HLE {
+/*
+ * Synchronizes access to the internal HLE kernel structures, it is acquired when a guest
+ * application thread performs a syscall. It should be acquired by any host threads that read or
+ * modify the HLE kernel state. Note: Any operation that directly or indirectly reads from or writes
+ * to the emulated memory is not protected by this mutex, and should be avoided in any threads other
+ * than the CPU thread.
+ */
+extern std::mutex g_hle_lock;
+} // namespace HLE

src/core/hle/svc.cpp

@@ -31,6 +31,7 @@
 #include "core/hle/kernel/timer.h"
 #include "core/hle/kernel/vm_manager.h"
 #include "core/hle/kernel/wait_object.h"
+#include "core/hle/lock.h"
 #include "core/hle/result.h"
 #include "core/hle/service/service.h"
 
@@ -1188,7 +1189,7 @@ struct FunctionDef {
     Func* func;
     const char* name;
 };
-}
+} // namespace
 
 static const FunctionDef SVC_Table[] = {
     {0x00, nullptr, "Unknown"},
@@ -1332,6 +1333,9 @@ MICROPROFILE_DEFINE(Kernel_SVC, "Kernel", "SVC", MP_RGB(70, 200, 70));
 void CallSVC(u32 immediate) {
     MICROPROFILE_SCOPE(Kernel_SVC);
 
+    // Lock the global kernel mutex when we enter the kernel HLE.
+    std::lock_guard<std::mutex> lock(HLE::g_hle_lock);
+
     const FunctionDef* info = GetSVCInfo(immediate);
     if (info) {
         if (info->func) {
@@ -1342,4 +1346,4 @@ void CallSVC(u32 immediate) {
     }
 }
 
-} // namespace
+} // namespace SVC