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/* IBM_PROLOG_BEGIN_TAG */
/* This is an automatically generated prolog. */
/* */
/* $Source: src/include/kernel/spte.H $ */
/* */
/* OpenPOWER HostBoot Project */
/* */
/* COPYRIGHT International Business Machines Corp. 2011,2014 */
/* */
/* Licensed under the Apache License, Version 2.0 (the "License"); */
/* you may not use this file except in compliance with the License. */
/* You may obtain a copy of the License at */
/* */
/* http://www.apache.org/licenses/LICENSE-2.0 */
/* */
/* Unless required by applicable law or agreed to in writing, software */
/* distributed under the License is distributed on an "AS IS" BASIS, */
/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or */
/* implied. See the License for the specific language governing */
/* permissions and limitations under the License. */
/* */
/* IBM_PROLOG_END_TAG */
/** @file spte.H
* @brief Defines the structure of the Shadow Page Table Entry.
*/
#ifndef __KERNEL_SPTE_H
#define __KERNEL_SPTE_H
#include <stdint.h>
#include <builtins.h>
/** @class ShadowPTE
* @brief Stores information needed in a shadow page table for virtual to
* physical address mapping, such as physical page number and
* security permissions.
*
* @note This structure only allows addressing of 4GB of physical memory due
* to the page number being stored in a 20 bit field.
*
* The data within is stored in a way so that the union value is an address
* within the physical page who's number is stored and the low-order bits
* are used for storing misc information about the page, such as permissions.
*/
class ShadowPTE
{
protected:
union
{
uint32_t word;
struct
{
/** Physical page number. */
uint32_t page:20;
/** Page is present (is PN valid?). */
uint32_t present:1;
/** May the page be read */
uint32_t readable:1;
/** May the page be written to. */
uint32_t writable:1;
/** May code be executed off page. */
uint32_t executable:1;
/** Should the dirty bit be maintained. */
uint32_t track_write:1;
/** Has page been written to. */
uint32_t dirty:1;
/** Allocate from a zero'd page. */
uint32_t allocate_from_zero:1;
/** LRU value - lower means it was accessed more recently. */
uint32_t last_access:3;
/** Reserved for future use. */
uint32_t reserved:2;
} PACKED;
};
public:
/** Initialize PTE */
ShadowPTE() : word(0) {};
/** Cast-construct from integer directly to the data union. */
explicit ShadowPTE(uint32_t i_data) : word(i_data) {};
/** Get physical page (as address). */
uint32_t getPageAddr() const { return (page << 12); };
/** Set physical page (as address). */
void setPageAddr(uint32_t i_page) { page = (i_page >> 12); };
/** Get physical page (as page number). */
uint32_t getPage() const { return page; }
/** Get present bit. */
bool isPresent() const { return present; };
/** Set present bit. */
void setPresent(bool i_present) { present = i_present; };
/** Get readable bit. */
bool isReadable() const { return readable; };
/** Set readable bit. */
void setReadable(bool i_read) { readable = i_read; };
/** Get writable bit. */
bool isWritable() const { return writable; };
/** Set writable bit. */
void setWritable(bool i_write) { writable = i_write; };
/** Get executable bit. */
bool isExecutable() const { return executable; };
/** Set executable bit. */
void setExecutable(bool i_exec) { executable = i_exec; };
/** Get write-tracked bit. */
bool isWriteTracked() const { return track_write; };
/** Set write-tracked bit. */
void setWriteTracked(bool i_track) { track_write = i_track; };
/** Get dirty bit. */
bool isDirty() const { return dirty; };
/** Set dirty bit. */
void setDirty(bool i_dirty) { dirty = i_dirty; };
/** Get allocate-from-zero bit. */
bool isAllocateFromZero() const { return allocate_from_zero; };
/** Set allocate-from-zero bit. */
void setAllocateFromZero(bool i_zero) { allocate_from_zero = i_zero; };
/** Get last_acces bits. */
uint8_t getLRU() const { return last_access; };
/** Increment the LRU bits. */
void incLRU() {
if( last_access < 0b111 )
{
last_access++;
}
};
/** Decrement the LRU bits. */
void decLRU() {
if( last_access > 0 )
{
last_access--;
}
};
/** Zero out the LRU bits. */
void zeroLRU() {
last_access = 0;
};
};
#endif
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