15 files changed, 458 insertions, 356 deletions

diff --git a/src/core/hle/kernel/address_arbiter.cpp b/src/core/hle/kernel/address_arbiter.cpp
index 37eec4c84..b5a0cc3a3 100644
--- a/src/core/hle/kernel/address_arbiter.cpp
+++ b/src/core/hle/kernel/address_arbiter.cpp
@@ -79,8 +79,6 @@ ResultCode AddressArbiter::ArbitrateAddress(ArbitrationType type, VAddr address,
                           ErrorSummary::WrongArgument, ErrorLevel::Usage);
     }
 
-    HLE::Reschedule(__func__);
-
     // The calls that use a timeout seem to always return a Timeout error even if they did not put
     // the thread to sleep
     if (type == ArbitrationType::WaitIfLessThanWithTimeout ||
diff --git a/src/core/hle/kernel/client_port.cpp b/src/core/hle/kernel/client_port.cpp
index aedc6f989..22645f4ec 100644
--- a/src/core/hle/kernel/client_port.cpp
+++ b/src/core/hle/kernel/client_port.cpp
@@ -4,12 +4,44 @@
 
 #include "common/assert.h"
 #include "core/hle/kernel/client_port.h"
+#include "core/hle/kernel/client_session.h"
 #include "core/hle/kernel/kernel.h"
 #include "core/hle/kernel/server_port.h"
+#include "core/hle/kernel/server_session.h"
 
 namespace Kernel {
 
 ClientPort::ClientPort() {}
 ClientPort::~ClientPort() {}
 
+ResultVal<SharedPtr<ClientSession>> ClientPort::Connect() {
+    // Note: Threads do not wait for the server endpoint to call
+    // AcceptSession before returning from this call.
+
+    if (active_sessions >= max_sessions) {
+        // TODO(Subv): Return an error code in this situation after session disconnection is
+        // implemented.
+        /*return ResultCode(ErrorDescription::MaxConnectionsReached,
+                          ErrorModule::OS, ErrorSummary::WouldBlock,
+                          ErrorLevel::Temporary);*/
+    }
+    active_sessions++;
+
+    // Create a new session pair, let the created sessions inherit the parent port's HLE handler.
+    auto sessions =
+        ServerSession::CreateSessionPair(server_port->GetName(), server_port->hle_handler);
+    auto client_session = std::get<SharedPtr<ClientSession>>(sessions);
+    auto server_session = std::get<SharedPtr<ServerSession>>(sessions);
+
+    if (server_port->hle_handler)
+        server_port->hle_handler->ClientConnected(server_session);
+
+    server_port->pending_sessions.push_back(std::move(server_session));
+
+    // Wake the threads waiting on the ServerPort
+    server_port->WakeupAllWaitingThreads();
+
+    return MakeResult<SharedPtr<ClientSession>>(std::move(client_session));
+}
+
 } // namespace
diff --git a/src/core/hle/kernel/client_port.h b/src/core/hle/kernel/client_port.h
index d28147718..511490c7c 100644
--- a/src/core/hle/kernel/client_port.h
+++ b/src/core/hle/kernel/client_port.h
@@ -11,8 +11,9 @@
 namespace Kernel {
 
 class ServerPort;
+class ClientSession;
 
-class ClientPort : public Object {
+class ClientPort final : public Object {
 public:
     friend class ServerPort;
     std::string GetTypeName() const override {
@@ -27,12 +28,20 @@ public:
         return HANDLE_TYPE;
     }
 
+    /**
+     * Creates a new Session pair, adds the created ServerSession to the associated ServerPort's
+     * list of pending sessions, and signals the ServerPort, causing any threads
+     * waiting on it to awake.
+     * @returns ClientSession The client endpoint of the created Session pair, or error code.
+     */
+    ResultVal<SharedPtr<ClientSession>> Connect();
+
     SharedPtr<ServerPort> server_port; ///< ServerPort associated with this client port.
     u32 max_sessions;    ///< Maximum number of simultaneous sessions the port can have
     u32 active_sessions; ///< Number of currently open sessions to this port
     std::string name;    ///< Name of client port (optional)
 
-protected:
+private:
     ClientPort();
     ~ClientPort() override;
 };
diff --git a/src/core/hle/kernel/client_session.cpp b/src/core/hle/kernel/client_session.cpp
new file mode 100644
index 000000000..0331386ec
--- /dev/null
+++ b/src/core/hle/kernel/client_session.cpp
@@ -0,0 +1,40 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/assert.h"
+
+#include "core/hle/kernel/client_session.h"
+#include "core/hle/kernel/server_session.h"
+
+namespace Kernel {
+
+ClientSession::ClientSession() = default;
+ClientSession::~ClientSession() {
+    // This destructor will be called automatically when the last ClientSession handle is closed by
+    // the emulated application.
+
+    if (server_session->hle_handler)
+        server_session->hle_handler->ClientDisconnected(server_session);
+
+    // TODO(Subv): If the session is still open, set the connection status to 2 (Closed by client),
+    // wake up all the ServerSession's waiting threads and set the WaitSynchronization result to
+    // 0xC920181A.
+}
+
+ResultVal<SharedPtr<ClientSession>> ClientSession::Create(ServerSession* server_session,
+                                                          std::string name) {
+    SharedPtr<ClientSession> client_session(new ClientSession);
+
+    client_session->name = std::move(name);
+    client_session->server_session = server_session;
+    client_session->session_status = SessionStatus::Open;
+    return MakeResult<SharedPtr<ClientSession>>(std::move(client_session));
+}
+
+ResultCode ClientSession::SendSyncRequest() {
+    // Signal the server session that new data is available
+    return server_session->HandleSyncRequest();
+}
+
+} // namespace
diff --git a/src/core/hle/kernel/client_session.h b/src/core/hle/kernel/client_session.h
new file mode 100644
index 000000000..ed468dec6
--- /dev/null
+++ b/src/core/hle/kernel/client_session.h
@@ -0,0 +1,65 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <string>
+
+#include "common/common_types.h"
+
+#include "core/hle/kernel/kernel.h"
+
+namespace Kernel {
+
+class ServerSession;
+
+enum class SessionStatus {
+    Open = 1,
+    ClosedByClient = 2,
+    ClosedBYServer = 3,
+};
+
+class ClientSession final : public Object {
+public:
+    friend class ServerSession;
+
+    std::string GetTypeName() const override {
+        return "ClientSession";
+    }
+
+    std::string GetName() const override {
+        return name;
+    }
+
+    static const HandleType HANDLE_TYPE = HandleType::ClientSession;
+    HandleType GetHandleType() const override {
+        return HANDLE_TYPE;
+    }
+
+    /**
+     * Sends an SyncRequest from the current emulated thread.
+     * @return ResultCode of the operation.
+     */
+    ResultCode SendSyncRequest();
+
+    std::string name;              ///< Name of client port (optional)
+    ServerSession* server_session; ///< The server session associated with this client session.
+    SessionStatus session_status;  ///< The session's current status.
+
+private:
+    ClientSession();
+    ~ClientSession() override;
+
+    /**
+     * Creates a client session.
+     * @param server_session The server session associated with this client session
+     * @param name Optional name of client session
+     * @return The created client session
+     */
+    static ResultVal<SharedPtr<ClientSession>> Create(ServerSession* server_session,
+                                                      std::string name = "Unknown");
+};
+
+} // namespace
diff --git a/src/core/hle/kernel/kernel.cpp b/src/core/hle/kernel/kernel.cpp
index 0c8752670..1db8e102f 100644
--- a/src/core/hle/kernel/kernel.cpp
+++ b/src/core/hle/kernel/kernel.cpp
@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 
 #include <algorithm>
+#include <boost/range/algorithm_ext/erase.hpp>
 #include "common/assert.h"
 #include "common/logging/log.h"
 #include "core/hle/config_mem.h"
@@ -31,13 +32,61 @@ void WaitObject::RemoveWaitingThread(Thread* thread) {
         waiting_threads.erase(itr);
 }
 
-void WaitObject::WakeupAllWaitingThreads() {
-    for (auto thread : waiting_threads)
-        thread->ResumeFromWait();
+SharedPtr<Thread> WaitObject::GetHighestPriorityReadyThread() {
+    // Remove the threads that are ready or already running from our waitlist
+    boost::range::remove_erase_if(waiting_threads, [](const SharedPtr<Thread>& thread) {
+        return thread->status == THREADSTATUS_RUNNING || thread->status == THREADSTATUS_READY ||
+               thread->status == THREADSTATUS_DEAD;
+    });
+
+    // TODO(Subv): This call should be performed inside the loop below to check if an object can be
+    // acquired by a particular thread. This is useful for things like recursive locking of Mutexes.
+    if (ShouldWait())
+        return nullptr;
+
+    Thread* candidate = nullptr;
+    s32 candidate_priority = THREADPRIO_LOWEST + 1;
+
+    for (const auto& thread : waiting_threads) {
+        if (thread->current_priority >= candidate_priority)
+            continue;
 
-    waiting_threads.clear();
+        bool ready_to_run =
+            std::none_of(thread->wait_objects.begin(), thread->wait_objects.end(),
+                         [](const SharedPtr<WaitObject>& object) { return object->ShouldWait(); });
+        if (ready_to_run) {
+            candidate = thread.get();
+            candidate_priority = thread->current_priority;
+        }
+    }
+
+    return candidate;
+}
 
-    HLE::Reschedule(__func__);
+void WaitObject::WakeupAllWaitingThreads() {
+    while (auto thread = GetHighestPriorityReadyThread()) {
+        if (!thread->IsSleepingOnWaitAll()) {
+            Acquire();
+            // Set the output index of the WaitSynchronizationN call to the index of this object.
+            if (thread->wait_set_output) {
+                thread->SetWaitSynchronizationOutput(thread->GetWaitObjectIndex(this));
+                thread->wait_set_output = false;
+            }
+        } else {
+            for (auto& object : thread->wait_objects) {
+                object->Acquire();
+                object->RemoveWaitingThread(thread.get());
+            }
+            // Note: This case doesn't update the output index of WaitSynchronizationN.
+            // Clear the thread's waitlist
+            thread->wait_objects.clear();
+        }
+
+        thread->SetWaitSynchronizationResult(RESULT_SUCCESS);
+        thread->ResumeFromWait();
+        // Note: Removing the thread from the object's waitlist will be
+        // done by GetHighestPriorityReadyThread.
+    }
 }
 
 const std::vector<SharedPtr<Thread>>& WaitObject::GetWaitingThreads() const {
diff --git a/src/core/hle/kernel/kernel.h b/src/core/hle/kernel/kernel.h
index 231cf7b75..1adcf6c71 100644
--- a/src/core/hle/kernel/kernel.h
+++ b/src/core/hle/kernel/kernel.h
@@ -31,22 +31,21 @@ enum KernelHandle : Handle {
 };
 
 enum class HandleType : u32 {
-    Unknown = 0,
-
-    Session = 2,
-    Event = 3,
-    Mutex = 4,
-    SharedMemory = 5,
-    Redirection = 6,
-    Thread = 7,
-    Process = 8,
-    AddressArbiter = 9,
-    Semaphore = 10,
-    Timer = 11,
-    ResourceLimit = 12,
-    CodeSet = 13,
-    ClientPort = 14,
-    ServerPort = 15,
+    Unknown,
+    Event,
+    Mutex,
+    SharedMemory,
+    Thread,
+    Process,
+    AddressArbiter,
+    Semaphore,
+    Timer,
+    ResourceLimit,
+    CodeSet,
+    ClientPort,
+    ServerPort,
+    ClientSession,
+    ServerSession,
 };
 
 enum {
@@ -82,23 +81,23 @@ public:
      */
     bool IsWaitable() const {
         switch (GetHandleType()) {
-        case HandleType::Session:
-        case HandleType::ServerPort:
         case HandleType::Event:
         case HandleType::Mutex:
         case HandleType::Thread:
         case HandleType::Semaphore:
         case HandleType::Timer:
+        case HandleType::ServerPort:
+        case HandleType::ServerSession:
             return true;
 
         case HandleType::Unknown:
         case HandleType::SharedMemory:
-        case HandleType::Redirection:
         case HandleType::Process:
         case HandleType::AddressArbiter:
         case HandleType::ResourceLimit:
         case HandleType::CodeSet:
         case HandleType::ClientPort:
+        case HandleType::ClientSession:
             return false;
         }
     }
@@ -152,9 +151,15 @@ public:
      */
     void RemoveWaitingThread(Thread* thread);
 
-    /// Wake up all threads waiting on this object
+    /**
+     * Wake up all threads waiting on this object that can be awoken, in priority order,
+     * and set the synchronization result and output of the thread.
+     */
     void WakeupAllWaitingThreads();
 
+    /// Obtains the highest priority thread that is ready to run from this object's waiting list.
+    SharedPtr<Thread> GetHighestPriorityReadyThread();
+
     /// Get a const reference to the waiting threads list for debug use
     const std::vector<SharedPtr<Thread>>& GetWaitingThreads() const;
 
diff --git a/src/core/hle/kernel/server_port.cpp b/src/core/hle/kernel/server_port.cpp
index 8e3ec8a14..6c19aa7c0 100644
--- a/src/core/hle/kernel/server_port.cpp
+++ b/src/core/hle/kernel/server_port.cpp
@@ -24,12 +24,14 @@ void ServerPort::Acquire() {
 }
 
 std::tuple<SharedPtr<ServerPort>, SharedPtr<ClientPort>> ServerPort::CreatePortPair(
-    u32 max_sessions, std::string name) {
+    u32 max_sessions, std::string name,
+    std::shared_ptr<Service::SessionRequestHandler> hle_handler) {
 
     SharedPtr<ServerPort> server_port(new ServerPort);
     SharedPtr<ClientPort> client_port(new ClientPort);
 
     server_port->name = name + "_Server";
+    server_port->hle_handler = std::move(hle_handler);
     client_port->name = name + "_Client";
     client_port->server_port = server_port;
     client_port->max_sessions = max_sessions;
diff --git a/src/core/hle/kernel/server_port.h b/src/core/hle/kernel/server_port.h
index fa9448ca0..b0f8df62c 100644
--- a/src/core/hle/kernel/server_port.h
+++ b/src/core/hle/kernel/server_port.h
@@ -4,11 +4,16 @@
 
 #pragma once
 
+#include <memory>
 #include <string>
 #include <tuple>
 #include "common/common_types.h"
 #include "core/hle/kernel/kernel.h"
 
+namespace Service {
+class SessionRequestHandler;
+}
+
 namespace Kernel {
 
 class ClientPort;
@@ -19,10 +24,13 @@ public:
      * Creates a pair of ServerPort and an associated ClientPort.
      * @param max_sessions Maximum number of sessions to the port
      * @param name Optional name of the ports
+     * @param hle_handler Optional HLE handler template for the port,
+     * ServerSessions crated from this port will inherit a reference to this handler.
      * @return The created port tuple
      */
     static std::tuple<SharedPtr<ServerPort>, SharedPtr<ClientPort>> CreatePortPair(
-        u32 max_sessions, std::string name = "UnknownPort");
+        u32 max_sessions, std::string name = "UnknownPort",
+        std::shared_ptr<Service::SessionRequestHandler> hle_handler = nullptr);
 
     std::string GetTypeName() const override {
         return "ServerPort";
@@ -41,6 +49,10 @@ public:
     std::vector<SharedPtr<WaitObject>>
         pending_sessions; ///< ServerSessions waiting to be accepted by the port
 
+    /// This session's HLE request handler template (optional)
+    /// ServerSessions created from this port inherit a reference to this handler.
+    std::shared_ptr<Service::SessionRequestHandler> hle_handler;
+
     bool ShouldWait() override;
     void Acquire() override;
 
diff --git a/src/core/hle/kernel/server_session.cpp b/src/core/hle/kernel/server_session.cpp
new file mode 100644
index 000000000..146458c1c
--- /dev/null
+++ b/src/core/hle/kernel/server_session.cpp
@@ -0,0 +1,79 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <tuple>
+
+#include "core/hle/kernel/client_session.h"
+#include "core/hle/kernel/server_session.h"
+#include "core/hle/kernel/thread.h"
+
+namespace Kernel {
+
+ServerSession::ServerSession() = default;
+ServerSession::~ServerSession() {
+    // This destructor will be called automatically when the last ServerSession handle is closed by
+    // the emulated application.
+    // TODO(Subv): Reduce the ClientPort's connection count,
+    // if the session is still open, set the connection status to 3 (Closed by server),
+}
+
+ResultVal<SharedPtr<ServerSession>> ServerSession::Create(
+    std::string name, std::shared_ptr<Service::SessionRequestHandler> hle_handler) {
+    SharedPtr<ServerSession> server_session(new ServerSession);
+
+    server_session->name = std::move(name);
+    server_session->signaled = false;
+    server_session->hle_handler = std::move(hle_handler);
+
+    return MakeResult<SharedPtr<ServerSession>>(std::move(server_session));
+}
+
+bool ServerSession::ShouldWait() {
+    return !signaled;
+}
+
+void ServerSession::Acquire() {
+    ASSERT_MSG(!ShouldWait(), "object unavailable!");
+    signaled = false;
+}
+
+ResultCode ServerSession::HandleSyncRequest() {
+    // The ServerSession received a sync request, this means that there's new data available
+    // from its ClientSession, so wake up any threads that may be waiting on a svcReplyAndReceive or
+    // similar.
+
+    // If this ServerSession has an associated HLE handler, forward the request to it.
+    if (hle_handler != nullptr) {
+        // Attempt to translate the incoming request's command buffer.
+        ResultCode result = TranslateHLERequest(this);
+        if (result.IsError())
+            return result;
+        hle_handler->HandleSyncRequest(SharedPtr<ServerSession>(this));
+        // TODO(Subv): Translate the response command buffer.
+    }
+
+    // If this ServerSession does not have an HLE implementation, just wake up the threads waiting
+    // on it.
+    signaled = true;
+    WakeupAllWaitingThreads();
+    return RESULT_SUCCESS;
+}
+
+ServerSession::SessionPair ServerSession::CreateSessionPair(
+    const std::string& name, std::shared_ptr<Service::SessionRequestHandler> hle_handler) {
+    auto server_session =
+        ServerSession::Create(name + "_Server", std::move(hle_handler)).MoveFrom();
+    // We keep a non-owning pointer to the ServerSession in the ClientSession because we don't want
+    // to prevent the ServerSession's destructor from being called when the emulated
+    // application closes the last ServerSession handle.
+    auto client_session = ClientSession::Create(server_session.get(), name + "_Client").MoveFrom();
+
+    return std::make_tuple(std::move(server_session), std::move(client_session));
+}
+
+ResultCode TranslateHLERequest(ServerSession* server_session) {
+    // TODO(Subv): Implement this function once multiple concurrent processes are supported.
+    return RESULT_SUCCESS;
+}
+}
diff --git a/src/core/hle/kernel/server_session.h b/src/core/hle/kernel/server_session.h
new file mode 100644
index 000000000..458284a5d
--- /dev/null
+++ b/src/core/hle/kernel/server_session.h
@@ -0,0 +1,94 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <string>
+#include "common/assert.h"
+#include "common/common_types.h"
+#include "core/hle/kernel/kernel.h"
+#include "core/hle/kernel/thread.h"
+#include "core/hle/result.h"
+#include "core/hle/service/service.h"
+#include "core/memory.h"
+
+namespace Kernel {
+
+class ClientSession;
+
+/**
+ * Kernel object representing the server endpoint of an IPC session. Sessions are the basic CTR-OS
+ * primitive for communication between different processes, and are used to implement service calls
+ * to the various system services.
+ *
+ * To make a service call, the client must write the command header and parameters to the buffer
+ * located at offset 0x80 of the TLS (Thread-Local Storage) area, then execute a SendSyncRequest
+ * SVC call with its ClientSession handle. The kernel will read the command header, using it to
+ * marshall the parameters to the process at the server endpoint of the session.
+ * After the server replies to the request, the response is marshalled back to the caller's
+ * TLS buffer and control is transferred back to it.
+ */
+class ServerSession final : public WaitObject {
+public:
+    std::string GetTypeName() const override {
+        return "ServerSession";
+    }
+
+    static const HandleType HANDLE_TYPE = HandleType::ServerSession;
+    HandleType GetHandleType() const override {
+        return HANDLE_TYPE;
+    }
+
+    using SessionPair = std::tuple<SharedPtr<ServerSession>, SharedPtr<ClientSession>>;
+
+    /**
+     * Creates a pair of ServerSession and an associated ClientSession.
+     * @param name Optional name of the ports
+     * @return The created session tuple
+     */
+    static SessionPair CreateSessionPair(
+        const std::string& name = "Unknown",
+        std::shared_ptr<Service::SessionRequestHandler> hle_handler = nullptr);
+
+    /**
+     * Handle a sync request from the emulated application.
+     * @returns ResultCode from the operation.
+     */
+    ResultCode HandleSyncRequest();
+
+    bool ShouldWait() override;
+
+    void Acquire() override;
+
+    std::string name; ///< The name of this session (optional)
+    bool signaled;    ///< Whether there's new data available to this ServerSession
+    std::shared_ptr<Service::SessionRequestHandler>
+        hle_handler; ///< This session's HLE request handler (optional)
+
+private:
+    ServerSession();
+    ~ServerSession() override;
+
+    /**
+     * Creates a server session. The server session can have an optional HLE handler,
+     * which will be invoked to handle the IPC requests that this session receives.
+     * @param name Optional name of the server session.
+     * @param hle_handler Optional HLE handler for this server session.
+     * @return The created server session
+     */
+    static ResultVal<SharedPtr<ServerSession>> Create(
+        std::string name = "Unknown",
+        std::shared_ptr<Service::SessionRequestHandler> hle_handler = nullptr);
+};
+
+/**
+ * Performs command buffer translation for an HLE IPC request.
+ * The command buffer from the ServerSession thread's TLS is copied into a
+ * buffer and all descriptors in the buffer are processed.
+ * TODO(Subv): Implement this function, currently we do not support multiple processes running at
+ * once, but once that is implemented we'll need to properly translate all descriptors
+ * in the command buffer.
+ */
+ResultCode TranslateHLERequest(ServerSession* server_session);
+}
diff --git a/src/core/hle/kernel/session.h b/src/core/hle/kernel/session.h
deleted file mode 100644
index ec025f732..000000000
--- a/src/core/hle/kernel/session.h
+++ /dev/null
@@ -1,218 +0,0 @@
-// Copyright 2014 Citra Emulator Project
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#pragma once
-
-#include <string>
-#include "common/assert.h"
-#include "common/common_types.h"
-#include "core/hle/kernel/kernel.h"
-#include "core/hle/kernel/thread.h"
-#include "core/hle/result.h"
-#include "core/memory.h"
-
-namespace IPC {
-
-enum DescriptorType : u32 {
-    // Buffer related desciptors types (mask : 0x0F)
-    StaticBuffer = 0x02,
-    PXIBuffer = 0x04,
-    MappedBuffer = 0x08,
-    // Handle related descriptors types (mask : 0x30, but need to check for buffer related
-    // descriptors first )
-    CopyHandle = 0x00,
-    MoveHandle = 0x10,
-    CallingPid = 0x20,
-};
-
-/**
- * @brief Creates a command header to be used for IPC
- * @param command_id            ID of the command to create a header for.
- * @param normal_params         Size of the normal parameters in words. Up to 63.
- * @param translate_params_size Size of the translate parameters in words. Up to 63.
- * @return The created IPC header.
- *
- * Normal parameters are sent directly to the process while the translate parameters might go
- * through modifications and checks by the kernel.
- * The translate parameters are described by headers generated with the IPC::*Desc functions.
- *
- * @note While #normal_params is equivalent to the number of normal parameters,
- * #translate_params_size includes the size occupied by the translate parameters headers.
- */
-constexpr u32 MakeHeader(u16 command_id, unsigned int normal_params,
-                         unsigned int translate_params_size) {
-    return (u32(command_id) << 16) | ((u32(normal_params) & 0x3F) << 6) |
-           (u32(translate_params_size) & 0x3F);
-}
-
-union Header {
-    u32 raw;
-    BitField<0, 6, u32> translate_params_size;
-    BitField<6, 6, u32> normal_params;
-    BitField<16, 16, u32> command_id;
-};
-
-inline Header ParseHeader(u32 header) {
-    return {header};
-}
-
-constexpr u32 MoveHandleDesc(u32 num_handles = 1) {
-    return MoveHandle | ((num_handles - 1) << 26);
-}
-
-constexpr u32 CopyHandleDesc(u32 num_handles = 1) {
-    return CopyHandle | ((num_handles - 1) << 26);
-}
-
-constexpr u32 CallingPidDesc() {
-    return CallingPid;
-}
-
-constexpr bool isHandleDescriptor(u32 descriptor) {
-    return (descriptor & 0xF) == 0x0;
-}
-
-constexpr u32 HandleNumberFromDesc(u32 handle_descriptor) {
-    return (handle_descriptor >> 26) + 1;
-}
-
-constexpr u32 StaticBufferDesc(u32 size, u8 buffer_id) {
-    return StaticBuffer | (size << 14) | ((buffer_id & 0xF) << 10);
-}
-
-union StaticBufferDescInfo {
-    u32 raw;
-    BitField<10, 4, u32> buffer_id;
-    BitField<14, 18, u32> size;
-};
-
-inline StaticBufferDescInfo ParseStaticBufferDesc(const u32 desc) {
-    return {desc};
-}
-
-/**
- * @brief Creates a header describing a buffer to be sent over PXI.
- * @param size         Size of the buffer. Max 0x00FFFFFF.
- * @param buffer_id    The Id of the buffer. Max 0xF.
- * @param is_read_only true if the buffer is read-only. If false, the buffer is considered to have
- * read-write access.
- * @return The created PXI buffer header.
- *
- * The next value is a phys-address of a table located in the BASE memregion.
- */
-inline u32 PXIBufferDesc(u32 size, unsigned buffer_id, bool is_read_only) {
-    u32 type = PXIBuffer;
-    if (is_read_only)
-        type |= 0x2;
-    return type | (size << 8) | ((buffer_id & 0xF) << 4);
-}
-
-enum MappedBufferPermissions {
-    R = 1,
-    W = 2,
-    RW = R | W,
-};
-
-constexpr u32 MappedBufferDesc(u32 size, MappedBufferPermissions perms) {
-    return MappedBuffer | (size << 4) | (u32(perms) << 1);
-}
-
-union MappedBufferDescInfo {
-    u32 raw;
-    BitField<4, 28, u32> size;
-    BitField<1, 2, MappedBufferPermissions> perms;
-};
-
-inline MappedBufferDescInfo ParseMappedBufferDesc(const u32 desc) {
-    return {desc};
-}
-
-inline DescriptorType GetDescriptorType(u32 descriptor) {
-    // Note: Those checks must be done in this order
-    if (isHandleDescriptor(descriptor))
-        return (DescriptorType)(descriptor & 0x30);
-
-    // handle the fact that the following descriptors can have rights
-    if (descriptor & MappedBuffer)
-        return MappedBuffer;
-
-    if (descriptor & PXIBuffer)
-        return PXIBuffer;
-
-    return StaticBuffer;
-}
-
-} // namespace IPC
-
-namespace Kernel {
-
-static const int kCommandHeaderOffset = 0x80; ///< Offset into command buffer of header
-
-/**
- * Returns a pointer to the command buffer in the current thread's TLS
- * TODO(Subv): This is not entirely correct, the command buffer should be copied from
- * the thread's TLS to an intermediate buffer in kernel memory, and then copied again to
- * the service handler process' memory.
- * @param offset Optional offset into command buffer
- * @return Pointer to command buffer
- */
-inline u32* GetCommandBuffer(const int offset = 0) {
-    return (u32*)Memory::GetPointer(GetCurrentThread()->GetTLSAddress() + kCommandHeaderOffset +
-                                    offset);
-}
-
-/**
- * Kernel object representing the client endpoint of an IPC session. Sessions are the basic CTR-OS
- * primitive for communication between different processes, and are used to implement service calls
- * to the various system services.
- *
- * To make a service call, the client must write the command header and parameters to the buffer
- * located at offset 0x80 of the TLS (Thread-Local Storage) area, then execute a SendSyncRequest
- * SVC call with its Session handle. The kernel will read the command header, using it to marshall
- * the parameters to the process at the server endpoint of the session. After the server replies to
- * the request, the response is marshalled back to the caller's TLS buffer and control is
- * transferred back to it.
- *
- * In Citra, only the client endpoint is currently implemented and only HLE calls, where the IPC
- * request is answered by C++ code in the emulator, are supported. When SendSyncRequest is called
- * with the session handle, this class's SyncRequest method is called, which should read the TLS
- * buffer and emulate the call accordingly. Since the code can directly read the emulated memory,
- * no parameter marshalling is done.
- *
- * In the long term, this should be turned into the full-fledged IPC mechanism implemented by
- * CTR-OS so that IPC calls can be optionally handled by the real implementations of processes, as
- * opposed to HLE simulations.
- */
-class Session : public WaitObject {
-public:
-    Session();
-    ~Session() override;
-
-    std::string GetTypeName() const override {
-        return "Session";
-    }
-
-    static const HandleType HANDLE_TYPE = HandleType::Session;
-    HandleType GetHandleType() const override {
-        return HANDLE_TYPE;
-    }
-
-    /**
-     * Handles a synchronous call to this session using HLE emulation. Emulated <-> emulated calls
-     * aren't supported yet.
-     */
-    virtual ResultVal<bool> SyncRequest() = 0;
-
-    // TODO(bunnei): These functions exist to satisfy a hardware test with a Session object
-    // passed into WaitSynchronization. Figure out the meaning of them.
-
-    bool ShouldWait() override {
-        return true;
-    }
-
-    void Acquire() override {
-        ASSERT_MSG(!ShouldWait(), "object unavailable!");
-    }
-};
-}
diff --git a/src/core/hle/kernel/thread.cpp b/src/core/hle/kernel/thread.cpp
index 84d6d24c6..4bbc08516 100644
--- a/src/core/hle/kernel/thread.cpp
+++ b/src/core/hle/kernel/thread.cpp
@@ -120,8 +120,6 @@ void Thread::Stop() {
     u32 tls_slot =
         ((tls_address - Memory::TLS_AREA_VADDR) % Memory::PAGE_SIZE) / Memory::TLS_ENTRY_SIZE;
     Kernel::g_current_process->tls_slots[tls_page].reset(tls_slot);
-
-    HLE::Reschedule(__func__);
 }
 
 Thread* ArbitrateHighestPriorityThread(u32 address) {
@@ -181,50 +179,6 @@ static void PriorityBoostStarvedThreads() {
 }
 
 /**
- * Gets the registers for timeout parameter of the next WaitSynchronization call.
- * @param thread a pointer to the thread that is ready to call WaitSynchronization
- * @returns a tuple of two register pointers to low and high part of the timeout parameter
- */
-static std::tuple<u32*, u32*> GetWaitSynchTimeoutParameterRegister(Thread* thread) {
-    bool thumb_mode = (thread->context.cpsr & TBIT) != 0;
-    u16 thumb_inst = Memory::Read16(thread->context.pc & 0xFFFFFFFE);
-    u32 inst = Memory::Read32(thread->context.pc & 0xFFFFFFFC) & 0x0FFFFFFF;
-
-    if ((thumb_mode && thumb_inst == 0xDF24) || (!thumb_mode && inst == 0x0F000024)) {
-        // svc #0x24 (WaitSynchronization1)
-        return std::make_tuple(&thread->context.cpu_registers[2],
-                               &thread->context.cpu_registers[3]);
-    } else if ((thumb_mode && thumb_inst == 0xDF25) || (!thumb_mode && inst == 0x0F000025)) {
-        // svc #0x25 (WaitSynchronizationN)
-        return std::make_tuple(&thread->context.cpu_registers[0],
-                               &thread->context.cpu_registers[4]);
-    }
-
-    UNREACHABLE();
-}
-
-/**
- * Updates the WaitSynchronization timeout parameter according to the difference
- * between ticks of the last WaitSynchronization call and the incoming one.
- * @param timeout_low a pointer to the register for the low part of the timeout parameter
- * @param timeout_high a pointer to the register for the high part of the timeout parameter
- * @param last_tick tick of the last WaitSynchronization call
- */
-static void UpdateTimeoutParameter(u32* timeout_low, u32* timeout_high, u64 last_tick) {
-    s64 timeout = ((s64)*timeout_high << 32) | *timeout_low;
-
-    if (timeout != -1) {
-        timeout -= cyclesToUs(CoreTiming::GetTicks() - last_tick) * 1000; // in nanoseconds
-
-        if (timeout < 0)
-            timeout = 0;
-
-        *timeout_low = timeout & 0xFFFFFFFF;
-        *timeout_high = timeout >> 32;
-    }
-}
-
-/**
  * Switches the CPU's active thread context to that of the specified thread
  * @param new_thread The thread to switch to
  */
@@ -254,32 +208,6 @@ static void SwitchContext(Thread* new_thread) {
 
         current_thread = new_thread;
 
-        // If the thread was waited by a svcWaitSynch call, step back PC by one instruction to rerun
-        // the SVC when the thread wakes up. This is necessary to ensure that the thread can acquire
-        // the requested wait object(s) before continuing.
-        if (new_thread->waitsynch_waited) {
-            // CPSR flag indicates CPU mode
-            bool thumb_mode = (new_thread->context.cpsr & TBIT) != 0;
-
-            // SVC instruction is 2 bytes for THUMB, 4 bytes for ARM
-            new_thread->context.pc -= thumb_mode ? 2 : 4;
-
-            // Get the register for timeout parameter
-            u32 *timeout_low, *timeout_high;
-            std::tie(timeout_low, timeout_high) = GetWaitSynchTimeoutParameterRegister(new_thread);
-
-            // Update the timeout parameter
-            UpdateTimeoutParameter(timeout_low, timeout_high, new_thread->last_running_ticks);
-        }
-
-        // Clean up the thread's wait_objects, they'll be restored if needed during
-        // the svcWaitSynchronization call
-        for (size_t i = 0; i < new_thread->wait_objects.size(); ++i) {
-            SharedPtr<WaitObject> object = new_thread->wait_objects[i];
-            object->RemoveWaitingThread(new_thread);
-        }
-        new_thread->wait_objects.clear();
-
         ready_queue.remove(new_thread->current_priority, new_thread);
         new_thread->status = THREADSTATUS_RUNNING;
 
@@ -319,17 +247,13 @@ static Thread* PopNextReadyThread() {
 void WaitCurrentThread_Sleep() {
     Thread* thread = GetCurrentThread();
     thread->status = THREADSTATUS_WAIT_SLEEP;
-
-    HLE::Reschedule(__func__);
 }
 
 void WaitCurrentThread_WaitSynchronization(std::vector<SharedPtr<WaitObject>> wait_objects,
-                                           bool wait_set_output, bool wait_all) {
+                                           bool wait_set_output) {
     Thread* thread = GetCurrentThread();
     thread->wait_set_output = wait_set_output;
-    thread->wait_all = wait_all;
     thread->wait_objects = std::move(wait_objects);
-    thread->waitsynch_waited = true;
     thread->status = THREADSTATUS_WAIT_SYNCH;
 }
 
@@ -351,15 +275,15 @@ static void ThreadWakeupCallback(u64 thread_handle, int cycles_late) {
         return;
     }
 
-    thread->waitsynch_waited = false;
-
     if (thread->status == THREADSTATUS_WAIT_SYNCH || thread->status == THREADSTATUS_WAIT_ARB) {
+        thread->wait_set_output = false;
+        // Remove the thread from each of its waiting objects' waitlists
+        for (auto& object : thread->wait_objects)
+            object->RemoveWaitingThread(thread.get());
+        thread->wait_objects.clear();
         thread->SetWaitSynchronizationResult(ResultCode(ErrorDescription::Timeout, ErrorModule::OS,
                                                         ErrorSummary::StatusChanged,
                                                         ErrorLevel::Info));
-
-        if (thread->wait_set_output)
-            thread->SetWaitSynchronizationOutput(-1);
     }
 
     thread->ResumeFromWait();
@@ -399,6 +323,7 @@ void Thread::ResumeFromWait() {
 
     ready_queue.push_back(current_priority, this);
     status = THREADSTATUS_READY;
+    HLE::Reschedule(__func__);
 }
 
 /**
@@ -494,13 +419,11 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
     thread->last_running_ticks = CoreTiming::GetTicks();
     thread->processor_id = processor_id;
     thread->wait_set_output = false;
-    thread->wait_all = false;
     thread->wait_objects.clear();
     thread->wait_address = 0;
     thread->name = std::move(name);
     thread->callback_handle = wakeup_callback_handle_table.Create(thread).MoveFrom();
     thread->owner_process = g_current_process;
-    thread->waitsynch_waited = false;
 
     // Find the next available TLS index, and mark it as used
     auto& tls_slots = Kernel::g_current_process->tls_slots;
@@ -555,8 +478,6 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
     ready_queue.push_back(thread->current_priority, thread.get());
     thread->status = THREADSTATUS_READY;
 
-    HLE::Reschedule(__func__);
-
     return MakeResult<SharedPtr<Thread>>(std::move(thread));
 }
 
@@ -619,14 +540,6 @@ void Reschedule() {
 
     HLE::DoneRescheduling();
 
-    // Don't bother switching to the same thread.
-    // But if the thread was waiting on objects, we still need to switch it
-    // to perform PC modification, change state to RUNNING, etc.
-    // This occurs in the case when an object the thread is waiting on immediately wakes up
-    // the current thread before Reschedule() is called.
-    if (next == cur && (next == nullptr || next->waitsynch_waited == false))
-        return;
-
     if (cur && next) {
         LOG_TRACE(Kernel, "context switch %u -> %u", cur->GetObjectId(), next->GetObjectId());
     } else if (cur) {
diff --git a/src/core/hle/kernel/thread.h b/src/core/hle/kernel/thread.h
index e0ffcea8a..238359fc5 100644
--- a/src/core/hle/kernel/thread.h
+++ b/src/core/hle/kernel/thread.h
@@ -5,7 +5,9 @@
 #pragma once
 
 #include <string>
+#include <unordered_map>
 #include <vector>
+#include <boost/container/flat_map.hpp>
 #include <boost/container/flat_set.hpp>
 #include "common/common_types.h"
 #include "core/core.h"
@@ -125,6 +127,16 @@ public:
     void SetWaitSynchronizationOutput(s32 output);
 
     /**
+     * Retrieves the index that this particular object occupies in the list of objects
+     * that the thread passed to WaitSynchronizationN.
+     * It is used to set the output value of WaitSynchronizationN when the thread is awakened.
+     * @param object Object to query the index of.
+     */
+    s32 GetWaitObjectIndex(const WaitObject* object) const {
+        return wait_objects_index.at(object->GetObjectId());
+    }
+
+    /**
      * Stops a thread, invalidating it from further use
      */
     void Stop();
@@ -137,6 +149,15 @@ public:
         return tls_address;
     }
 
+    /**
+     * Returns whether this thread is waiting for all the objects in
+     * its wait list to become ready, as a result of a WaitSynchronizationN call
+     * with wait_all = true, or a ReplyAndReceive call.
+     */
+    bool IsSleepingOnWaitAll() const {
+        return !wait_objects.empty();
+    }
+
     Core::ThreadContext context;
 
     u32 thread_id;
@@ -154,16 +175,22 @@ public:
 
     VAddr tls_address; ///< Virtual address of the Thread Local Storage of the thread
 
-    bool waitsynch_waited; ///< Set to true if the last svcWaitSynch call caused the thread to wait
-
     /// Mutexes currently held by this thread, which will be released when it exits.
     boost::container::flat_set<SharedPtr<Mutex>> held_mutexes;
 
-    SharedPtr<Process> owner_process;                ///< Process that owns this thread
-    std::vector<SharedPtr<WaitObject>> wait_objects; ///< Objects that the thread is waiting on
-    VAddr wait_address;   ///< If waiting on an AddressArbiter, this is the arbitration address
-    bool wait_all;        ///< True if the thread is waiting on all objects before resuming
-    bool wait_set_output; ///< True if the output parameter should be set on thread wakeup
+    SharedPtr<Process> owner_process; ///< Process that owns this thread
+
+    /// Objects that the thread is waiting on.
+    /// This is only populated when the thread should wait for all the objects to become ready.
+    std::vector<SharedPtr<WaitObject>> wait_objects;
+
+    /// Mapping of Object ids to their position in the last waitlist that this object waited on.
+    boost::container::flat_map<int, s32> wait_objects_index;
+
+    VAddr wait_address; ///< If waiting on an AddressArbiter, this is the arbitration address
+
+    /// True if the WaitSynchronizationN output parameter should be set on thread wakeup.
+    bool wait_set_output;
 
     std::string name;
 
@@ -215,10 +242,9 @@ void WaitCurrentThread_Sleep();
  * @param wait_objects Kernel objects that we are waiting on
  * @param wait_set_output If true, set the output parameter on thread wakeup (for
  * WaitSynchronizationN only)
- * @param wait_all If true, wait on all objects before resuming (for WaitSynchronizationN only)
  */
 void WaitCurrentThread_WaitSynchronization(std::vector<SharedPtr<WaitObject>> wait_objects,
-                                           bool wait_set_output, bool wait_all);
+                                           bool wait_set_output);
 
 /**
  * Waits the current thread from an ArbitrateAddress call
diff --git a/src/core/hle/kernel/timer.cpp b/src/core/hle/kernel/timer.cpp
index eac181f4e..b50cf520d 100644
--- a/src/core/hle/kernel/timer.cpp
+++ b/src/core/hle/kernel/timer.cpp
@@ -60,14 +60,10 @@ void Timer::Set(s64 initial, s64 interval) {
     u64 initial_microseconds = initial / 1000;
     CoreTiming::ScheduleEvent(usToCycles(initial_microseconds), timer_callback_event_type,
                               callback_handle);
-
-    HLE::Reschedule(__func__);
 }
 
 void Timer::Cancel() {
     CoreTiming::UnscheduleEvent(timer_callback_event_type, callback_handle);
-
-    HLE::Reschedule(__func__);
 }
 
 void Timer::Clear() {