Memory.h

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//===-- Memory.h ------------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#ifndef LLDB_TARGET_MEMORY_H
#define LLDB_TARGET_MEMORY_H
 
#include "lldb/Utility/RangeMap.h"
#include "lldb/lldb-private.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include <map>
#include <mutex>
#include <vector>
 
namespace lldb_private {
// A class to track memory that was read from a live process between
// runs.
class MemoryCache {
public:
  // Constructors and Destructors
  MemoryCache(Process &process);
 
  ~MemoryCache();
 
  void Clear(bool clear_invalid_ranges = false);
 
  void Flush(lldb::addr_t addr, size_t size);
 
  size_t Read(lldb::addr_t addr, void *dst, size_t dst_len, Status &error);
 
  /// Reads multiple memory ranges, serving cache hits from L1 and L2 and
  /// batching all misses through Process::DoReadMemoryRanges. The semantics of
  /// the return value match Process::ReadMemoryRanges.
  llvm::SmallVector<llvm::MutableArrayRef<uint8_t>>
  ReadRanges(llvm::ArrayRef<Range<lldb::addr_t, size_t>> ranges,
             llvm::MutableArrayRef<uint8_t> buffer);
 
  uint32_t GetMemoryCacheLineSize() const { return m_L2_cache_line_byte_size; }
 
  void AddInvalidRange(lldb::addr_t base_addr, lldb::addr_t byte_size);
 
  bool RemoveInvalidRange(lldb::addr_t base_addr, lldb::addr_t byte_size);
 
  // Allow external sources to populate data into the L1 memory cache
  void AddL1CacheData(lldb::addr_t addr, const void *src, size_t src_len);
 
  void AddL1CacheData(lldb::addr_t addr, llvm::ArrayRef<uint8_t> src) {
    if (!src.empty())
      AddL1CacheData(addr, src.data(), src.size());
  }
 
  void AddL1CacheData(lldb::addr_t addr,
                      const lldb::DataBufferSP &data_buffer_sp);
 
protected:
  typedef std::map<lldb::addr_t, lldb::DataBufferSP> BlockMap;
  typedef RangeVector<lldb::addr_t, lldb::addr_t, 4> InvalidRanges;
  typedef Range<lldb::addr_t, lldb::addr_t> AddrRange;
  // Classes that inherit from MemoryCache can see and modify these
  std::recursive_mutex m_mutex;
  BlockMap m_L1_cache; // A first level memory cache whose chunk sizes vary that
                       // will be used only if the memory read fits entirely in
                       // a chunk
  BlockMap m_L2_cache; // A memory cache of fixed size chinks
                       // (m_L2_cache_line_byte_size bytes in size each)
  InvalidRanges m_invalid_ranges;
  Process &m_process;
  uint32_t m_L2_cache_line_byte_size;
 
private:
  MemoryCache(const MemoryCache &) = delete;
  const MemoryCache &operator=(const MemoryCache &) = delete;
 
  lldb::DataBufferSP GetL2CacheLine(lldb::addr_t addr, Status &error);
 
  // If the entire range [addr, addr+len) is covered by a single L1 entry,
  // returns a pointer into that entry's data at the correct offset. Returns
  // nullptr on a miss. Caller must hold m_mutex.
  const uint8_t *FindL1CacheEntry(lldb::addr_t addr, size_t len) const;
 
  // If the entire range [addr, addr+len) is covered by a single cache line
  // that is already in L2, returns a pointer into that line's data at the
  // correct offset. Never reads from the inferior. Returns nullptr on a miss.
  // Caller must hold m_mutex.
  const uint8_t *FindL2CacheEntry(lldb::addr_t addr, size_t len) const;
 
  // Looks the range [addr, addr+len) up in L1 and then L2, returning a pointer
  // into the data of whichever entry covers it. Returns nullptr on a miss.
  // Caller must hold m_mutex.
  const uint8_t *FindCacheEntry(lldb::addr_t addr, size_t len) const;
};
 
    
 
class AllocatedBlock {
public:
  AllocatedBlock(lldb::addr_t addr, uint32_t byte_size, uint32_t permissions,
                 uint32_t chunk_size);
 
  ~AllocatedBlock();
 
  lldb::addr_t ReserveBlock(uint32_t size);
 
  bool FreeBlock(lldb::addr_t addr);
 
  lldb::addr_t GetBaseAddress() const { return m_range.GetRangeBase(); }
 
  uint32_t GetByteSize() const { return m_range.GetByteSize(); }
 
  uint32_t GetPermissions() const { return m_permissions; }
 
  uint32_t GetChunkSize() const { return m_chunk_size; }
 
  bool Contains(lldb::addr_t addr) const {
    return m_range.Contains(addr);
  }
 
protected:
  uint32_t TotalChunks() const { return GetByteSize() / GetChunkSize(); }
 
  uint32_t CalculateChunksNeededForSize(uint32_t size) const {
    return (size + m_chunk_size - 1) / m_chunk_size;
  }
  // Base address of this block of memory 4GB of chunk should be enough.
  Range<lldb::addr_t, uint32_t> m_range;
  // Permissions for this memory (logical OR of lldb::Permissions bits)
  const uint32_t m_permissions;
  // The size of chunks that the memory at m_addr is divied up into.
  const uint32_t m_chunk_size;
  // A sorted list of free address ranges.
  RangeVector<lldb::addr_t, uint32_t> m_free_blocks;
  // A sorted list of reserved address.
  RangeVector<lldb::addr_t, uint32_t> m_reserved_blocks;
};
 
// A class that can track allocated memory and give out allocated memory
// without us having to make an allocate/deallocate call every time we need
// some memory in a process that is being debugged.
class AllocatedMemoryCache {
public:
  // Constructors and Destructors
  AllocatedMemoryCache(Process &process);
 
  ~AllocatedMemoryCache();
 
  void Clear(bool deallocate_memory);
 
  lldb::addr_t AllocateMemory(size_t byte_size, uint32_t permissions,
                              Status &error);
 
  bool DeallocateMemory(lldb::addr_t ptr);
 
  bool IsInCache(lldb::addr_t addr) const;
 
protected:
  typedef std::shared_ptr<AllocatedBlock> AllocatedBlockSP;
 
  AllocatedBlockSP AllocatePage(uint32_t byte_size, uint32_t permissions,
                                uint32_t chunk_size, Status &error);
 
  // Classes that inherit from MemoryCache can see and modify these
  Process &m_process;
  mutable std::recursive_mutex m_mutex;
  typedef std::multimap<uint32_t, AllocatedBlockSP> PermissionsToBlockMap;
  PermissionsToBlockMap m_memory_map;
 
private:
  AllocatedMemoryCache(const AllocatedMemoryCache &) = delete;
  const AllocatedMemoryCache &operator=(const AllocatedMemoryCache &) = delete;
};
 
} // namespace lldb_private
 
#endif // LLDB_TARGET_MEMORY_H