/*
 * Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
 * Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
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 *    of conditions and the following disclaimer in the documentation and/or other materials
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/**
 * @defgroup los_arch_mmu architecture mmu
 * @ingroup kernel
 */

#ifndef __LOS_ARCH_MMU_H__
#define __LOS_ARCH_MMU_H__

#include "los_typedef.h"
#include "los_mux.h"

#ifdef __cplusplus
#if __cplusplus
extern "C" {
#endif /* __cplusplus */
#endif /* __cplusplus */
/**************************************************************************************************
 https://blog.csdn.net/kuangyufei/article/details/109032636
 https://blog.csdn.net/qq_38410730/article/details/81036768
 虚拟内存空间中的地址叫做“虚拟地址”；而实际物理内存空间中的地址叫做“实际物理地址”或“物理地址”。处理器
 运算器和应用程序设计人员看到的只是虚拟内存空间和虚拟地址，而处理器片外的地址总线看到的只是物理地址空间和物理地址。
 MMU是 MemoryManagementUnit 的缩写即，内存管理单元. 
 MMU 的作用：
1. 将虚拟地址翻译成为物理地址，然后访问实际的物理地址
2. 访问权限控制
当处理器试图访问一个虚存页面时，首先到页表中去查询该页是否已映射到物理页框中，并记录在页表中。如果在，
则MMU会把页码转换成页框码，并加上虚拟地址提供的页内偏移量形成物理地址后去访问物理内存；如果不在，
则意味着该虚存页面还没有被载入内存，这时MMU就会通知操作系统：发生了一个页面访问错误（页面错误），
接下来系统会启动所谓的“请页”机制，即调用相应的系统操作函数，判断该虚拟地址是否为有效地址。

如果是有效的地址，就从虚拟内存中将该地址指向的页面读入到内存中的一个空闲页框中，并在页表中添加上
相对应的表项，最后处理器将从发生页面错误的地方重新开始运行；如果是无效的地址，则表明进程在试图访问
一个不存在的虚拟地址，此时操作系统将终止此次访问。
**************************************************************************************************/
typedef struct ArchMmu {//内存管理单元
    LosMux              mtx;            /**< arch mmu page table entry modification mutex lock *///对页表操作的互斥量
    VADDR_T             *virtTtb;       /**< translation table base virtual addr */ //注意:这里是个指针,内核操作都用这个地址
    PADDR_T             physTtb;        /**< translation table base phys addr */	//注意:这里是个值,这个值是记录给MMU使用的,MMU只认它,内核是无法使用的
    UINT32              asid;           /**< TLB asid */			//标识进程用的，由mmu分配，有了它在mmu层面才知道是哪个进程的虚拟地址
    LOS_DL_LIST         ptList;         /**< page table vm page list *///L1 为表头，后面挂的是n多L2
} LosArchMmu;

BOOL OsArchMmuInit(LosArchMmu *archMmu, VADDR_T *virtTtb);
STATUS_T LOS_ArchMmuQuery(const LosArchMmu *archMmu, VADDR_T vaddr, PADDR_T *paddr, UINT32 *flags);
STATUS_T LOS_ArchMmuUnmap(LosArchMmu *archMmu, VADDR_T vaddr, size_t count);
STATUS_T LOS_ArchMmuMap(LosArchMmu *archMmu, VADDR_T vaddr, PADDR_T paddr, size_t count, UINT32 flags);
STATUS_T LOS_ArchMmuChangeProt(LosArchMmu *archMmu, VADDR_T vaddr, size_t count, UINT32 flags);
STATUS_T LOS_ArchMmuMove(LosArchMmu *archMmu, VADDR_T oldVaddr, VADDR_T newVaddr, size_t count, UINT32 flags);
VOID LOS_ArchMmuContextSwitch(LosArchMmu *archMmu);
STATUS_T LOS_ArchMmuDestroy(LosArchMmu *archMmu);
VOID OsArchMmuInitPerCPU(VOID);
VADDR_T *OsGFirstTableGet(VOID);

#ifdef __cplusplus
#if __cplusplus
}
#endif /* __cplusplus */
#endif /* __cplusplus */

#endif /* __LOS_VM_PAGE_H__ */