Kernel: Add VMManager to manage process address spaces

This enables more dynamic management of the process address space,
compared to just directly configuring the page table for major areas.

This will serve as the foundation upon which the rest of the Kernel
memory management functions will be built.

1 files changed, 245 insertions, 0 deletions

diff --git a/src/core/hle/kernel/vm_manager.cpp b/src/core/hle/kernel/vm_manager.cpp
new file mode 100644
index 00000000..b2dd2154
--- /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;
+    }
+}
+
+}