11 files changed, 492 insertions, 111 deletions

diff --git a/src/core/hle/kernel/event.cpp b/src/core/hle/kernel/event.cpp
index e45deb1c6..f338f3266 100644
--- a/src/core/hle/kernel/event.cpp
+++ b/src/core/hle/kernel/event.cpp
@@ -41,10 +41,7 @@ void Event::Acquire() {
 
 void Event::Signal() {
     signaled = true;
-
     WakeupAllWaitingThreads();
-
-    HLE::Reschedule(__func__);
 }
 
 void Event::Clear() {
diff --git a/src/core/hle/kernel/kernel.cpp b/src/core/hle/kernel/kernel.cpp
index 726e4d2ff..20e11da16 100644
--- a/src/core/hle/kernel/kernel.cpp
+++ b/src/core/hle/kernel/kernel.cpp
@@ -32,27 +32,13 @@ void WaitObject::RemoveWaitingThread(Thread* thread) {
         waiting_threads.erase(itr);
 }
 
-SharedPtr<Thread> WaitObject::WakeupNextThread() {
-    if (waiting_threads.empty())
-        return nullptr;
-
-    auto next_thread = std::move(waiting_threads.front());
-    waiting_threads.erase(waiting_threads.begin());
-
-    next_thread->ReleaseWaitObject(this);
-
-    return next_thread;
-}
-
 void WaitObject::WakeupAllWaitingThreads() {
-    auto waiting_threads_copy = waiting_threads;
+    for (auto thread : waiting_threads)
+        thread->ResumeFromWait();
 
-    // We use a copy because ReleaseWaitObject will remove the thread from this object's
-    // waiting_threads list
-    for (auto thread : waiting_threads_copy)
-        thread->ReleaseWaitObject(this);
+    waiting_threads.clear();
 
-    ASSERT_MSG(waiting_threads.empty(), "failed to awaken all waiting threads!");
+    HLE::Reschedule(__func__);
 }
 
 HandleTable::HandleTable() {
diff --git a/src/core/hle/kernel/kernel.h b/src/core/hle/kernel/kernel.h
index a5a0f4800..64595f758 100644
--- a/src/core/hle/kernel/kernel.h
+++ b/src/core/hle/kernel/kernel.h
@@ -140,12 +140,6 @@ public:
      */
     void RemoveWaitingThread(Thread* thread);
 
-    /**
-     * Wake up the next thread waiting on this object
-     * @return Pointer to the thread that was resumed, nullptr if no threads are waiting
-     */
-    SharedPtr<Thread> WakeupNextThread();
-
     /// Wake up all threads waiting on this object
     void WakeupAllWaitingThreads();
 
diff --git a/src/core/hle/kernel/mutex.cpp b/src/core/hle/kernel/mutex.cpp
index 6aa73df86..edb97d324 100644
--- a/src/core/hle/kernel/mutex.cpp
+++ b/src/core/hle/kernel/mutex.cpp
@@ -23,12 +23,7 @@ static void ResumeWaitingThread(Mutex* mutex) {
     // Reset mutex lock thread handle, nothing is waiting
     mutex->lock_count = 0;
     mutex->holding_thread = nullptr;
-
-    // Find the next waiting thread for the mutex...
-    auto next_thread = mutex->WakeupNextThread();
-    if (next_thread != nullptr) {
-        mutex->Acquire(next_thread);
-    }
+    mutex->WakeupAllWaitingThreads();
 }
 
 void ReleaseThreadMutexes(Thread* thread) {
@@ -94,8 +89,6 @@ void Mutex::Release() {
             ResumeWaitingThread(this);
         }
     }
-
-    HLE::Reschedule(__func__);
 }
 
 } // namespace
diff --git a/src/core/hle/kernel/resource_limit.h b/src/core/hle/kernel/resource_limit.h
index 201ec0db9..1b8249c74 100644
--- a/src/core/hle/kernel/resource_limit.h
+++ b/src/core/hle/kernel/resource_limit.h
@@ -81,13 +81,13 @@ public:
     s32 max_timers = 0;
     s32 max_shared_mems = 0;
     s32 max_address_arbiters = 0;
-    
+
     /// Max CPU time that the processes in this category can utilize
     s32 max_cpu_time = 0;
 
-    // TODO(Subv): Increment these in their respective Kernel::T::Create functions, keeping in mind that 
-    // APPLICATION resource limits should not be affected by the objects created by service modules. 
-    // Currently we have no way of distinguishing if a Create was called by the running application, 
+    // TODO(Subv): Increment these in their respective Kernel::T::Create functions, keeping in mind that
+    // APPLICATION resource limits should not be affected by the objects created by service modules.
+    // Currently we have no way of distinguishing if a Create was called by the running application,
     // or by a service module. Approach this once we have separated the service modules into their own processes
 
     /// Current memory that the processes in this category are using
diff --git a/src/core/hle/kernel/semaphore.cpp b/src/core/hle/kernel/semaphore.cpp
index dbb4c9b7f..4b359ed07 100644
--- a/src/core/hle/kernel/semaphore.cpp
+++ b/src/core/hle/kernel/semaphore.cpp
@@ -42,19 +42,13 @@ void Semaphore::Acquire() {
 
 ResultVal<s32> Semaphore::Release(s32 release_count) {
     if (max_count - available_count < release_count)
-        return ResultCode(ErrorDescription::OutOfRange, ErrorModule::Kernel, 
+        return ResultCode(ErrorDescription::OutOfRange, ErrorModule::Kernel,
                           ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
 
     s32 previous_count = available_count;
     available_count += release_count;
 
-    // Notify some of the threads that the semaphore has been released
-    // stop once the semaphore is full again or there are no more waiting threads
-    while (!ShouldWait() && WakeupNextThread() != nullptr) {
-        Acquire();
-    }
-
-    HLE::Reschedule(__func__);
+    WakeupAllWaitingThreads();
 
     return MakeResult<s32>(previous_count);
 }
diff --git a/src/core/hle/kernel/thread.cpp b/src/core/hle/kernel/thread.cpp
index 690d33b55..4729a7fe0 100644
--- a/src/core/hle/kernel/thread.cpp
+++ b/src/core/hle/kernel/thread.cpp
@@ -13,6 +13,7 @@
 #include "common/thread_queue_list.h"
 
 #include "core/arm/arm_interface.h"
+#include "core/arm/skyeye_common/armdefs.h"
 #include "core/core.h"
 #include "core/core_timing.h"
 #include "core/hle/hle.h"
@@ -100,7 +101,7 @@ void Thread::Stop() {
     }
 
     status = THREADSTATUS_DEAD;
-    
+
     WakeupAllWaitingThreads();
 
     // Clean up any dangling references in objects that this thread was waiting for
@@ -169,7 +170,7 @@ static void PriorityBoostStarvedThreads() {
     }
 }
 
-/** 
+/**
  * Switches the CPU's active thread context to that of the specified thread
  * @param new_thread The thread to switch to
  */
@@ -193,8 +194,22 @@ static void SwitchContext(Thread* new_thread) {
     if (new_thread) {
         DEBUG_ASSERT_MSG(new_thread->status == THREADSTATUS_READY, "Thread must be ready to become running.");
 
+        // Cancel any outstanding wakeup events for this thread
+        CoreTiming::UnscheduleEvent(ThreadWakeupEventType, new_thread->callback_handle);
+
         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;
+        }
+
         ready_queue.remove(new_thread->current_priority, new_thread);
         new_thread->status = THREADSTATUS_RUNNING;
 
@@ -243,6 +258,7 @@ void WaitCurrentThread_WaitSynchronization(std::vector<SharedPtr<WaitObject>> wa
     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;
 }
 
@@ -268,6 +284,8 @@ static void ThreadWakeupCallback(u64 thread_handle, int cycles_late) {
         return;
     }
 
+    thread->waitsynch_waited = false;
+
     if (thread->status == THREADSTATUS_WAIT_SYNCH) {
         thread->SetWaitSynchronizationResult(ResultCode(ErrorDescription::Timeout, ErrorModule::OS,
                                                         ErrorSummary::StatusChanged, ErrorLevel::Info));
@@ -288,63 +306,20 @@ void Thread::WakeAfterDelay(s64 nanoseconds) {
     CoreTiming::ScheduleEvent(usToCycles(microseconds), ThreadWakeupEventType, callback_handle);
 }
 
-void Thread::ReleaseWaitObject(WaitObject* wait_object) {
-    if (status != THREADSTATUS_WAIT_SYNCH || wait_objects.empty()) {
-        LOG_CRITICAL(Kernel, "thread is not waiting on any objects!");
-        return;
-    }
-
-    // Remove this thread from the waiting object's thread list
-    wait_object->RemoveWaitingThread(this);
-
-    unsigned index = 0;
-    bool wait_all_failed = false; // Will be set to true if any object is unavailable
-
-    // Iterate through all waiting objects to check availability...
-    for (auto itr = wait_objects.begin(); itr != wait_objects.end(); ++itr) {
-        if ((*itr)->ShouldWait())
-            wait_all_failed = true;
-
-        // The output should be the last index of wait_object
-        if (*itr == wait_object)
-            index = itr - wait_objects.begin();
-    }
-
-    // If we are waiting on all objects...
-    if (wait_all) {
-        // Resume the thread only if all are available...
-        if (!wait_all_failed) {
-            SetWaitSynchronizationResult(RESULT_SUCCESS);
-            SetWaitSynchronizationOutput(-1);
-
-            ResumeFromWait();
-        }
-    } else {
-        // Otherwise, resume
-        SetWaitSynchronizationResult(RESULT_SUCCESS);
-
-        if (wait_set_output)
-            SetWaitSynchronizationOutput(index);
-
-        ResumeFromWait();
-    }
-}
-
 void Thread::ResumeFromWait() {
-    // Cancel any outstanding wakeup events for this thread
-    CoreTiming::UnscheduleEvent(ThreadWakeupEventType, callback_handle);
-
     switch (status) {
         case THREADSTATUS_WAIT_SYNCH:
-            // Remove this thread from all other WaitObjects
-            for (auto wait_object : wait_objects)
-                wait_object->RemoveWaitingThread(this);
-            break;
         case THREADSTATUS_WAIT_ARB:
         case THREADSTATUS_WAIT_SLEEP:
             break;
-        case THREADSTATUS_RUNNING:
+
         case THREADSTATUS_READY:
+            // If the thread is waiting on multiple wait objects, it might be awoken more than once
+            // before actually resuming. We can ignore subsequent wakeups if the thread status has
+            // already been set to THREADSTATUS_READY.
+            return;
+
+        case THREADSTATUS_RUNNING:
             DEBUG_ASSERT_MSG(false, "Thread with object id %u has already resumed.", GetObjectId());
             return;
         case THREADSTATUS_DEAD:
@@ -353,7 +328,7 @@ void Thread::ResumeFromWait() {
                 GetObjectId());
             return;
     }
-    
+
     ready_queue.push_back(current_priority, this);
     status = THREADSTATUS_READY;
 }
@@ -415,6 +390,7 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
     thread->callback_handle = wakeup_callback_handle_table.Create(thread).MoveFrom();
     thread->owner_process = g_current_process;
     thread->tls_index = -1;
+    thread->waitsynch_waited = false;
 
     // Find the next available TLS index, and mark it as used
     auto& used_tls_slots = Kernel::g_current_process->used_tls_slots;
@@ -504,7 +480,7 @@ void Reschedule() {
     } else if (next) {
         LOG_TRACE(Kernel, "context switch idle -> %u", next->GetObjectId());
     }
-    
+
     SwitchContext(next);
 }
 
diff --git a/src/core/hle/kernel/thread.h b/src/core/hle/kernel/thread.h
index 389928178..b8160bb2c 100644
--- a/src/core/hle/kernel/thread.h
+++ b/src/core/hle/kernel/thread.h
@@ -94,12 +94,6 @@ public:
      * @return The thread's ID
      */
     u32 GetThreadId() const { return thread_id; }
-    
-    /**
-     * Release an acquired wait object
-     * @param wait_object WaitObject to release
-     */
-    void ReleaseWaitObject(WaitObject* wait_object);
 
     /**
      * Resumes a thread from waiting
@@ -152,6 +146,8 @@ public:
 
     s32 tls_index; ///< Index 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;
 
@@ -163,12 +159,12 @@ public:
 
     std::string name;
 
+    /// Handle used as userdata to reference this object when inserting into the CoreTiming queue.
+    Handle callback_handle;
+
 private:
     Thread();
     ~Thread() override;
-
-    /// Handle used as userdata to reference this object when inserting into the CoreTiming queue.
-    Handle callback_handle;
 };
 
 /**
diff --git a/src/core/hle/kernel/timer.cpp b/src/core/hle/kernel/timer.cpp
index 25d066bf1..8aa4110a6 100644
--- a/src/core/hle/kernel/timer.cpp
+++ b/src/core/hle/kernel/timer.cpp
@@ -88,7 +88,7 @@ static void TimerCallback(u64 timer_handle, int cycles_late) {
     if (timer->interval_delay != 0) {
         // Reschedule the timer with the interval delay
         u64 interval_microseconds = timer->interval_delay / 1000;
-        CoreTiming::ScheduleEvent(usToCycles(interval_microseconds) - cycles_late, 
+        CoreTiming::ScheduleEvent(usToCycles(interval_microseconds) - cycles_late,
                 timer_callback_event_type, timer_handle);
     }
 }
diff --git a/src/core/hle/kernel/vm_manager.cpp b/src/core/hle/kernel/vm_manager.cpp
new file mode 100644
index 000000000..b2dd21542
--- /dev/null
+++ b/src/core/hle/kernel/vm_manager.cpp
@@ -0,0 +1,245 @@
+// Copyright 2015 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/vm_manager.h"
+#include "core/memory_setup.h"
+
+namespace Kernel {
+
+bool VirtualMemoryArea::CanBeMergedWith(const VirtualMemoryArea& next) const {
+    ASSERT(base + size == next.base);
+    if (permissions != next.permissions ||
+            meminfo_state != next.meminfo_state ||
+            type != next.type) {
+        return false;
+    }
+    if (type == VMAType::AllocatedMemoryBlock &&
+            (backing_block != next.backing_block || offset + size != next.offset)) {
+        return false;
+    }
+    if (type == VMAType::BackingMemory && backing_memory + size != next.backing_memory) {
+        return false;
+    }
+    if (type == VMAType::MMIO && paddr + size != next.paddr) {
+        return false;
+    }
+    return true;
+}
+
+VMManager::VMManager() {
+    Reset();
+}
+
+void VMManager::Reset() {
+    vma_map.clear();
+
+    // Initialize the map with a single free region covering the entire managed space.
+    VirtualMemoryArea initial_vma;
+    initial_vma.size = MAX_ADDRESS;
+    vma_map.emplace(initial_vma.base, initial_vma);
+
+    UpdatePageTableForVMA(initial_vma);
+}
+
+VMManager::VMAHandle VMManager::FindVMA(VAddr target) const {
+    return std::prev(vma_map.upper_bound(target));
+}
+
+ResultVal<VMManager::VMAHandle> VMManager::MapMemoryBlock(VAddr target,
+        std::shared_ptr<std::vector<u8>> block, u32 offset, u32 size, MemoryState state) {
+    ASSERT(block != nullptr);
+    ASSERT(offset + size <= block->size());
+
+    // This is the appropriately sized VMA that will turn into our allocation.
+    CASCADE_RESULT(VMAIter vma_handle, CarveVMA(target, size));
+    VirtualMemoryArea& final_vma = vma_handle->second;
+    ASSERT(final_vma.size == size);
+
+    final_vma.type = VMAType::AllocatedMemoryBlock;
+    final_vma.permissions = VMAPermission::ReadWrite;
+    final_vma.meminfo_state = state;
+    final_vma.backing_block = block;
+    final_vma.offset = offset;
+    UpdatePageTableForVMA(final_vma);
+
+    return MakeResult<VMAHandle>(MergeAdjacent(vma_handle));
+}
+
+ResultVal<VMManager::VMAHandle> VMManager::MapBackingMemory(VAddr target, u8 * memory, u32 size, MemoryState state) {
+    ASSERT(memory != nullptr);
+
+    // This is the appropriately sized VMA that will turn into our allocation.
+    CASCADE_RESULT(VMAIter vma_handle, CarveVMA(target, size));
+    VirtualMemoryArea& final_vma = vma_handle->second;
+    ASSERT(final_vma.size == size);
+
+    final_vma.type = VMAType::BackingMemory;
+    final_vma.permissions = VMAPermission::ReadWrite;
+    final_vma.meminfo_state = state;
+    final_vma.backing_memory = memory;
+    UpdatePageTableForVMA(final_vma);
+
+    return MakeResult<VMAHandle>(MergeAdjacent(vma_handle));
+}
+
+ResultVal<VMManager::VMAHandle> VMManager::MapMMIO(VAddr target, PAddr paddr, u32 size, MemoryState state) {
+    // This is the appropriately sized VMA that will turn into our allocation.
+    CASCADE_RESULT(VMAIter vma_handle, CarveVMA(target, size));
+    VirtualMemoryArea& final_vma = vma_handle->second;
+    ASSERT(final_vma.size == size);
+
+    final_vma.type = VMAType::MMIO;
+    final_vma.permissions = VMAPermission::ReadWrite;
+    final_vma.meminfo_state = state;
+    final_vma.paddr = paddr;
+    UpdatePageTableForVMA(final_vma);
+
+    return MakeResult<VMAHandle>(MergeAdjacent(vma_handle));
+}
+
+void VMManager::Unmap(VMAHandle vma_handle) {
+    VMAIter iter = StripIterConstness(vma_handle);
+
+    VirtualMemoryArea& vma = iter->second;
+    vma.type = VMAType::Free;
+    vma.permissions = VMAPermission::None;
+    vma.meminfo_state = MemoryState::Free;
+
+    vma.backing_block = nullptr;
+    vma.offset = 0;
+    vma.backing_memory = nullptr;
+    vma.paddr = 0;
+
+    UpdatePageTableForVMA(vma);
+
+    MergeAdjacent(iter);
+}
+
+void VMManager::Reprotect(VMAHandle vma_handle, VMAPermission new_perms) {
+    VMAIter iter = StripIterConstness(vma_handle);
+
+    VirtualMemoryArea& vma = iter->second;
+    vma.permissions = new_perms;
+    UpdatePageTableForVMA(vma);
+
+    MergeAdjacent(iter);
+}
+
+VMManager::VMAIter VMManager::StripIterConstness(const VMAHandle & iter) {
+    // This uses a neat C++ trick to convert a const_iterator to a regular iterator, given
+    // non-const access to its container.
+    return vma_map.erase(iter, iter); // Erases an empty range of elements
+}
+
+ResultVal<VMManager::VMAIter> VMManager::CarveVMA(VAddr base, u32 size) {
+    ASSERT_MSG((size & Memory::PAGE_MASK) == 0, "non-page aligned size: %8X", size);
+    ASSERT_MSG((base & Memory::PAGE_MASK) == 0, "non-page aligned base: %08X", base);
+
+    VMAIter vma_handle = StripIterConstness(FindVMA(base));
+    if (vma_handle == vma_map.end()) {
+        // Target address is outside the range managed by the kernel
+        return ResultCode(ErrorDescription::InvalidAddress, ErrorModule::OS,
+                ErrorSummary::InvalidArgument, ErrorLevel::Usage); // 0xE0E01BF5
+    }
+
+    VirtualMemoryArea& vma = vma_handle->second;
+    if (vma.type != VMAType::Free) {
+        // Region is already allocated
+        return ResultCode(ErrorDescription::InvalidAddress, ErrorModule::OS,
+                ErrorSummary::InvalidState, ErrorLevel::Usage); // 0xE0A01BF5
+    }
+
+    u32 start_in_vma = base - vma.base;
+    u32 end_in_vma = start_in_vma + size;
+
+    if (end_in_vma > vma.size) {
+        // Requested allocation doesn't fit inside VMA
+        return ResultCode(ErrorDescription::InvalidAddress, ErrorModule::OS,
+                ErrorSummary::InvalidState, ErrorLevel::Usage); // 0xE0A01BF5
+    }
+
+    if (end_in_vma != vma.size) {
+        // Split VMA at the end of the allocated region
+        SplitVMA(vma_handle, end_in_vma);
+    }
+    if (start_in_vma != 0) {
+        // Split VMA at the start of the allocated region
+        vma_handle = SplitVMA(vma_handle, start_in_vma);
+    }
+
+    return MakeResult<VMAIter>(vma_handle);
+}
+
+VMManager::VMAIter VMManager::SplitVMA(VMAIter vma_handle, u32 offset_in_vma) {
+    VirtualMemoryArea& old_vma = vma_handle->second;
+    VirtualMemoryArea new_vma = old_vma; // Make a copy of the VMA
+
+    // For now, don't allow no-op VMA splits (trying to split at a boundary) because it's probably
+    // a bug. This restriction might be removed later.
+    ASSERT(offset_in_vma < old_vma.size);
+    ASSERT(offset_in_vma > 0);
+
+    old_vma.size = offset_in_vma;
+    new_vma.base += offset_in_vma;
+    new_vma.size -= offset_in_vma;
+
+    switch (new_vma.type) {
+    case VMAType::Free:
+        break;
+    case VMAType::AllocatedMemoryBlock:
+        new_vma.offset += offset_in_vma;
+        break;
+    case VMAType::BackingMemory:
+        new_vma.backing_memory += offset_in_vma;
+        break;
+    case VMAType::MMIO:
+        new_vma.paddr += offset_in_vma;
+        break;
+    }
+
+    ASSERT(old_vma.CanBeMergedWith(new_vma));
+
+    return vma_map.emplace_hint(std::next(vma_handle), new_vma.base, new_vma);
+}
+
+VMManager::VMAIter VMManager::MergeAdjacent(VMAIter iter) {
+    VMAIter next_vma = std::next(iter);
+    if (next_vma != vma_map.end() && iter->second.CanBeMergedWith(next_vma->second)) {
+        iter->second.size += next_vma->second.size;
+        vma_map.erase(next_vma);
+    }
+
+    if (iter != vma_map.begin()) {
+        VMAIter prev_vma = std::prev(iter);
+        if (prev_vma->second.CanBeMergedWith(iter->second)) {
+            prev_vma->second.size += iter->second.size;
+            vma_map.erase(iter);
+            iter = prev_vma;
+        }
+    }
+
+    return iter;
+}
+
+void VMManager::UpdatePageTableForVMA(const VirtualMemoryArea& vma) {
+    switch (vma.type) {
+    case VMAType::Free:
+        Memory::UnmapRegion(vma.base, vma.size);
+        break;
+    case VMAType::AllocatedMemoryBlock:
+        Memory::MapMemoryRegion(vma.base, vma.size, vma.backing_block->data() + vma.offset);
+        break;
+    case VMAType::BackingMemory:
+        Memory::MapMemoryRegion(vma.base, vma.size, vma.backing_memory);
+        break;
+    case VMAType::MMIO:
+        // TODO(yuriks): Add support for MMIO handlers.
+        Memory::MapIoRegion(vma.base, vma.size);
+        break;
+    }
+}
+
+}
diff --git a/src/core/hle/kernel/vm_manager.h b/src/core/hle/kernel/vm_manager.h
new file mode 100644
index 000000000..22b724603
--- /dev/null
+++ b/src/core/hle/kernel/vm_manager.h
@@ -0,0 +1,200 @@
+// Copyright 2015 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "common/common_types.h"
+
+#include "core/hle/result.h"
+
+namespace Kernel {
+
+enum class VMAType : u8 {
+    /// VMA represents an unmapped region of the address space.
+    Free,
+    /// VMA is backed by a ref-counted allocate memory block.
+    AllocatedMemoryBlock,
+    /// VMA is backed by a raw, unmanaged pointer.
+    BackingMemory,
+    /// VMA is mapped to MMIO registers at a fixed PAddr.
+    MMIO,
+    // TODO(yuriks): Implement MemoryAlias to support MAP/UNMAP
+};
+
+/// Permissions for mapped memory blocks
+enum class VMAPermission : u8 {
+    None = 0,
+    Read = 1,
+    Write = 2,
+    Execute = 4,
+
+    ReadWrite = Read | Write,
+    ReadExecute = Read | Execute,
+    WriteExecute = Write | Execute,
+    ReadWriteExecute = Read | Write | Execute,
+};
+
+/// Set of values returned in MemoryInfo.state by svcQueryMemory.
+enum class MemoryState : u8 {
+    Free = 0,
+    Reserved = 1,
+    IO = 2,
+    Static = 3,
+    Code = 4,
+    Private = 5,
+    Shared = 6,
+    Continuous = 7,
+    Aliased = 8,
+    Alias = 9,
+    AliasCode = 10,
+    Locked = 11,
+};
+
+/**
+ * Represents a VMA in an address space. A VMA is a contiguous region of virtual addressing space
+ * with homogeneous attributes across its extents. In this particular implementation each VMA is
+ * also backed by a single host memory allocation.
+ */
+struct VirtualMemoryArea {
+    /// Virtual base address of the region.
+    VAddr base = 0;
+    /// Size of the region.
+    u32 size = 0;
+
+    VMAType type = VMAType::Free;
+    VMAPermission permissions = VMAPermission::None;
+    /// Tag returned by svcQueryMemory. Not otherwise used.
+    MemoryState meminfo_state = MemoryState::Free;
+
+    // Settings for type = AllocatedMemoryBlock
+    /// Memory block backing this VMA.
+    std::shared_ptr<std::vector<u8>> backing_block = nullptr;
+    /// Offset into the backing_memory the mapping starts from.
+    u32 offset = 0;
+
+    // Settings for type = BackingMemory
+    /// Pointer backing this VMA. It will not be destroyed or freed when the VMA is removed.
+    u8* backing_memory = nullptr;
+
+    // Settings for type = MMIO
+    /// Physical address of the register area this VMA maps to.
+    PAddr paddr = 0;
+
+    /// Tests if this area can be merged to the right with `next`.
+    bool CanBeMergedWith(const VirtualMemoryArea& next) const;
+};
+
+/**
+ * Manages a process' virtual addressing space. This class maintains a list of allocated and free
+ * regions in the address space, along with their attributes, and allows kernel clients to
+ * manipulate it, adjusting the page table to match.
+ *
+ * This is similar in idea and purpose to the VM manager present in operating system kernels, with
+ * the main difference being that it doesn't have to support swapping or memory mapping of files.
+ * The implementation is also simplified by not having to allocate page frames. See these articles
+ * about the Linux kernel for an explantion of the concept and implementation:
+ *  - http://duartes.org/gustavo/blog/post/how-the-kernel-manages-your-memory/
+ *  - http://duartes.org/gustavo/blog/post/page-cache-the-affair-between-memory-and-files/
+ */
+class VMManager {
+    // TODO(yuriks): Make page tables switchable to support multiple VMManagers
+public:
+    /**
+     * The maximum amount of address space managed by the kernel. Addresses above this are never used.
+     * @note This is the limit used by the New 3DS kernel. Old 3DS used 0x20000000.
+     */
+    static const u32 MAX_ADDRESS = 0x40000000;
+
+    /**
+     * A map covering the entirety of the managed address space, keyed by the `base` field of each
+     * VMA. It must always be modified by splitting or merging VMAs, so that the invariant
+     * `elem.base + elem.size == next.base` is preserved, and mergeable regions must always be
+     * merged when possible so that no two similar and adjacent regions exist that have not been
+     * merged.
+     */
+    std::map<VAddr, VirtualMemoryArea> vma_map;
+    using VMAHandle = decltype(vma_map)::const_iterator;
+
+    VMManager();
+
+    /// Clears the address space map, re-initializing with a single free area.
+    void Reset();
+
+    /// Finds the VMA in which the given address is included in, or `vma_map.end()`.
+    VMAHandle FindVMA(VAddr target) const;
+
+    // TODO(yuriks): Should these functions actually return the handle?
+
+    /**
+     * Maps part of a ref-counted block of memory at a given address.
+     *
+     * @param target The guest address to start the mapping at.
+     * @param block The block to be mapped.
+     * @param offset Offset into `block` to map from.
+     * @param size Size of the mapping.
+     * @param state MemoryState tag to attach to the VMA.
+     */
+    ResultVal<VMAHandle> MapMemoryBlock(VAddr target, std::shared_ptr<std::vector<u8>> block,
+            u32 offset, u32 size, MemoryState state);
+
+    /**
+     * Maps an unmanaged host memory pointer at a given address.
+     *
+     * @param target The guest address to start the mapping at.
+     * @param memory The memory to be mapped.
+     * @param size Size of the mapping.
+     * @param state MemoryState tag to attach to the VMA.
+     */
+    ResultVal<VMAHandle> MapBackingMemory(VAddr target, u8* memory, u32 size, MemoryState state);
+
+    /**
+     * Maps a memory-mapped IO region at a given address.
+     *
+     * @param target The guest address to start the mapping at.
+     * @param paddr The physical address where the registers are present.
+     * @param size Size of the mapping.
+     * @param state MemoryState tag to attach to the VMA.
+     */
+    ResultVal<VMAHandle> MapMMIO(VAddr target, PAddr paddr, u32 size, MemoryState state);
+
+    /// Unmaps the given VMA.
+    void Unmap(VMAHandle vma);
+
+    /// Changes the permissions of the given VMA.
+    void Reprotect(VMAHandle vma, VMAPermission new_perms);
+
+private:
+    using VMAIter = decltype(vma_map)::iterator;
+
+    /// Converts a VMAHandle to a mutable VMAIter.
+    VMAIter StripIterConstness(const VMAHandle& iter);
+
+    /**
+     * Carves a VMA of a specific size at the specified address by splitting Free VMAs while doing
+     * the appropriate error checking.
+     */
+    ResultVal<VMAIter> CarveVMA(VAddr base, u32 size);
+
+    /**
+     * Splits a VMA in two, at the specified offset.
+     * @returns the right side of the split, with the original iterator becoming the left side.
+     */
+    VMAIter SplitVMA(VMAIter vma, u32 offset_in_vma);
+
+    /**
+     * Checks for and merges the specified VMA with adjacent ones if possible.
+     * @returns the merged VMA or the original if no merging was possible.
+     */
+    VMAIter MergeAdjacent(VMAIter vma);
+
+    /// Updates the pages corresponding to this VMA so they match the VMA's attributes.
+    void UpdatePageTableForVMA(const VirtualMemoryArea& vma);
+};
+
+}