Merge pull request #2842 from Subv/switchable_page_table

Kernel/Memory: Give each process its own page table and allow switching the current page table upon reschedule

src/core/hle/kernel/memory.cpp

@@ -8,7 +8,6 @@
 #include <memory>
 #include <utility>
 #include <vector>
-#include "audio_core/audio_core.h"
 #include "common/assert.h"
 #include "common/common_types.h"
 #include "common/logging/log.h"
@@ -24,7 +23,7 @@
 
 namespace Kernel {
 
-static MemoryRegionInfo memory_regions[3];
+MemoryRegionInfo memory_regions[3];
 
 /// Size of the APPLICATION, SYSTEM and BASE memory regions (respectively) for each system
 /// memory configuration type.
@@ -96,9 +95,6 @@ MemoryRegionInfo* GetMemoryRegion(MemoryRegion region) {
     }
 }
 
-std::array<u8, Memory::VRAM_SIZE> vram;
-std::array<u8, Memory::N3DS_EXTRA_RAM_SIZE> n3ds_extra_ram;
-
 void HandleSpecialMapping(VMManager& address_space, const AddressMapping& mapping) {
     using namespace Memory;
 
@@ -143,30 +139,14 @@ void HandleSpecialMapping(VMManager& address_space, const AddressMapping& mappin
         return;
     }
 
-    // TODO(yuriks): Use GetPhysicalPointer when that becomes independent of the virtual
-    // mappings.
-    u8* target_pointer = nullptr;
-    switch (area->paddr_base) {
-    case VRAM_PADDR:
-        target_pointer = vram.data();
-        break;
-    case DSP_RAM_PADDR:
-        target_pointer = AudioCore::GetDspMemory().data();
-        break;
-    case N3DS_EXTRA_RAM_PADDR:
-        target_pointer = n3ds_extra_ram.data();
-        break;
-    default:
-        UNREACHABLE();
-    }
+    u8* target_pointer = Memory::GetPhysicalPointer(area->paddr_base + offset_into_region);
 
     // TODO(yuriks): This flag seems to have some other effect, but it's unknown what
     MemoryState memory_state = mapping.unk_flag ? MemoryState::Static : MemoryState::IO;
 
-    auto vma = address_space
-                   .MapBackingMemory(mapping.address, target_pointer + offset_into_region,
-                                     mapping.size, memory_state)
-                   .Unwrap();
+    auto vma =
+        address_space.MapBackingMemory(mapping.address, target_pointer, mapping.size, memory_state)
+            .Unwrap();
     address_space.Reprotect(vma,
                             mapping.read_only ? VMAPermission::Read : VMAPermission::ReadWrite);
 }

src/core/hle/kernel/memory.h

@@ -26,4 +26,6 @@ MemoryRegionInfo* GetMemoryRegion(MemoryRegion region);
 
 void HandleSpecialMapping(VMManager& address_space, const AddressMapping& mapping);
 void MapSharedPages(VMManager& address_space);
+
+extern MemoryRegionInfo memory_regions[3];
 } // namespace Kernel

src/core/hle/kernel/thread.cpp

@@ -171,6 +171,8 @@ static void SwitchContext(Thread* new_thread) {
         // Cancel any outstanding wakeup events for this thread
         CoreTiming::UnscheduleEvent(ThreadWakeupEventType, new_thread->callback_handle);
 
+        auto previous_process = Kernel::g_current_process;
+
         current_thread = new_thread;
 
         ready_queue.remove(new_thread->current_priority, new_thread);
@@ -178,8 +180,18 @@ static void SwitchContext(Thread* new_thread) {
 
         Core::CPU().LoadContext(new_thread->context);
         Core::CPU().SetCP15Register(CP15_THREAD_URO, new_thread->GetTLSAddress());
+
+        if (previous_process != current_thread->owner_process) {
+            Kernel::g_current_process = current_thread->owner_process;
+            Memory::current_page_table = &Kernel::g_current_process->vm_manager.page_table;
+            // We have switched processes and thus, page tables, clear the instruction cache so we
+            // don't keep stale data from the previous process.
+            Core::CPU().ClearInstructionCache();
+        }
     } else {
         current_thread = nullptr;
+        // Note: We do not reset the current process and current page table when idling because
+        // technically we haven't changed processes, our threads are just paused.
     }
 }
 

src/core/hle/kernel/vm_manager.cpp

@@ -56,6 +56,10 @@ void VMManager::Reset() {
     initial_vma.size = MAX_ADDRESS;
     vma_map.emplace(initial_vma.base, initial_vma);
 
+    page_table.pointers.fill(nullptr);
+    page_table.attributes.fill(Memory::PageType::Unmapped);
+    page_table.cached_res_count.fill(0);
+
     UpdatePageTableForVMA(initial_vma);
 }
 
@@ -328,16 +332,17 @@ VMManager::VMAIter VMManager::MergeAdjacent(VMAIter iter) {
 void VMManager::UpdatePageTableForVMA(const VirtualMemoryArea& vma) {
     switch (vma.type) {
     case VMAType::Free:
-        Memory::UnmapRegion(vma.base, vma.size);
+        Memory::UnmapRegion(page_table, vma.base, vma.size);
         break;
     case VMAType::AllocatedMemoryBlock:
-        Memory::MapMemoryRegion(vma.base, vma.size, vma.backing_block->data() + vma.offset);
+        Memory::MapMemoryRegion(page_table, vma.base, vma.size,
+                                vma.backing_block->data() + vma.offset);
         break;
     case VMAType::BackingMemory:
-        Memory::MapMemoryRegion(vma.base, vma.size, vma.backing_memory);
+        Memory::MapMemoryRegion(page_table, vma.base, vma.size, vma.backing_memory);
         break;
     case VMAType::MMIO:
-        Memory::MapIoRegion(vma.base, vma.size, vma.mmio_handler);
+        Memory::MapIoRegion(page_table, vma.base, vma.size, vma.mmio_handler);
         break;
     }
 }

src/core/hle/kernel/vm_manager.h

@@ -9,6 +9,7 @@
 #include <vector>
 #include "common/common_types.h"
 #include "core/hle/result.h"
+#include "core/memory.h"
 #include "core/mmio.h"
 
 namespace Kernel {
@@ -102,7 +103,6 @@ struct VirtualMemoryArea {
  *  - http://duartes.org/gustavo/blog/post/page-cache-the-affair-between-memory-and-files/
  */
 class VMManager final {
-    // 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
@@ -184,6 +184,10 @@ public:
     /// Dumps the address space layout to the log, for debugging
     void LogLayout(Log::Level log_level) const;
 
+    /// Each VMManager has its own page table, which is set as the main one when the owning process
+    /// is scheduled.
+    Memory::PageTable page_table;
+
 private:
     using VMAIter = decltype(vma_map)::iterator;