// 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 <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 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 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();
~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);
/// Dumps the address space layout to the log, for debugging
void LogLayout() const;
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);
};
}
