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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROMEOS_ASH_COMPONENTS_MEMORY_PAGEMAP_H_
#define CHROMEOS_ASH_COMPONENTS_MEMORY_PAGEMAP_H_
#include <sys/types.h>
#include <unistd.h>
#include <vector>
#include "base/component_export.h"
#include "base/files/scoped_file.h"
namespace ash {
namespace memory {
// Pagemap fetches pagemap entries from procfs for a process.
class COMPONENT_EXPORT(ASH_MEMORY) Pagemap {
public:
// For more information on the Pagemap layout see the kernel documentation at
// https://www.kernel.org/doc/Documentation/vm/pagemap.txt
struct PagemapEntry {
uint8_t swap_type : 5;
uint64_t swap_offset : 50;
bool pte_soft_dirty : 1;
bool page_exclusively_mapped : 1;
uint8_t : 4; // these bits are unused
bool page_file_or_shared_anon : 1;
bool page_swapped : 1;
bool page_present : 1;
} __attribute__((packed));
static_assert(sizeof(PagemapEntry) == sizeof(uint64_t),
"PagemapEntry is expected to be 8 bytes");
explicit Pagemap(pid_t pid);
Pagemap(const Pagemap&) = delete;
Pagemap& operator=(const Pagemap&) = delete;
~Pagemap();
bool IsValid() const;
// GetEntries will populate |entries| for the memory region specified.
// It is required that |address| be page aligned and |length| must always be a
// page length multiple. Additionally, |entries| is expected to be sized to
// the number of pages in the range specified. If it's not properly sized it
// will be resized to the appropriate length for the caller.
bool GetEntries(uint64_t address,
uint64_t length,
std::vector<PagemapEntry>* entries) const;
// GetNumberOfPagesPresent is a helper which makes it easy to quickly
// determine the number of pages in core for the region specified by |address|
// and |length|. On success the function will return true and pages_present
// will be set accordingly.
bool GetNumberOfPagesPresent(uint64_t address,
uint64_t length,
uint64_t* pages_present) const;
// IsFullyPresent is a small helper around GetNumberOfPagesPresent which
// returns true if every page in the range is presnt.
bool IsFullyPresent(uint64_t address, uint64_t length) const;
private:
friend class PagemapTest;
base::ScopedFD fd_;
};
} // namespace memory
} // namespace ash
#endif // CHROMEOS_ASH_COMPONENTS_MEMORY_PAGEMAP_H_
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