文章目录
- 一、vm_area_struct 结构体成员分析
-
- 1、vm_pgoff 成员
- 2、vm_file 成员
- 3、vm_private_data 成员
- 二、vm_area_struct 结构体完整源码
在博客 【Linux 内核 内存管理】虚拟地址空间布局架构 ⑦ ( vm_area_struct 结构体成员分析 | vm_start | vm_end | vm_next | vm_prev |vm_rb) 中 , 分析了 vm_start vm_end vm_next vm_prev vm_rb 这
个结构体成员作用 ;
在博客 【Linux 内核 内存管理】内存映射相关数据结构 ② ( vm_area_struct 结构体成员分析 | vm_mm 成员 | vm_page_prot 成员 | vm_flags 成员 ) 中 , 分析了 vm_area_struct 结构体中的 vm_mm vm_page_prot vm_flags 成员作用 ;
在博客 【Linux 内核 内存管理】内存映射相关数据结构 ③ ( vm_area_struct 结构体成员分析 | shared 成员 | anon_vma_chain 成员 | anon_vma 成员 ) 中 , 分析了 vm_area_struct 结构体中的 shared anon_vma_chain anon_vma 成员作用 ;
在博客 【Linux 内核 内存管理】内存映射相关数据结构 ④ ( vm_area_struct 结构体成员分析 | vm_ops 成员 | vm_operations_struct 结构体成员分析 ) 中 , 分析了 vm_area_struct 结构体中的 vm_ops 成员作用 , 以及分析了 vm_ops 成员的结构体类型 vm_operations_struct 的几个重要成员的作用 ;
一、vm_area_struct 结构体成员分析
1、vm_pgoff 成员
vm_area_struct 结构体 中的 vm_pgoff 成员 是 " 文件偏移 " , 其单位是 " 页 " ;
/* Information about our backing store: */
unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE
units */2、vm_file 成员
vm_area_struct 结构体 中的 vm_file 成员 是 " 内存映射 “ 中的 ” 文件映射 " 类型中 被映射的 文件 , 如果是 " 匿名映射 " 类型的 " 内存映射 " , 该成员为 NULL ;
struct file * vm_file; /* File we map to (can be NULL). */3、vm_private_data 成员
vm_area_struct 结构体 中的 vm_private_data 成员 用于指向 " 进程 “ 的 ” 用户虚拟地址空间 " 中的 " 私有数据 " ;
void * vm_private_data; /* was vm_pte (shared mem) */二、vm_area_struct 结构体完整源码
vm_area_struct 结构体完整源码 :
/*
* This struct defines a memory VMM memory area. There is one of these
* per VM-area/task. A VM area is any part of the process virtual memory
* space that has a special rule for the page-fault handlers (ie a shared
* library, the executable area etc).
*/
struct vm_area_struct {
/* The first cache line has the info for VMA tree walking. */
unsigned long vm_start; /* Our start address within vm_mm. */
unsigned long vm_end; /* The first byte after our end address
within vm_mm. */
/* linked list of VM areas per task, sorted by address */
struct vm_area_struct *vm_next, *vm_prev;
struct rb_node vm_rb;
/*
* Largest free memory gap in bytes to the left of this VMA.
* Either between this VMA and vma->vm_prev, or between one of the
* VMAs below us in the VMA rbtree and its ->vm_prev. This helps
* get_unmapped_area find a free area of the right size.
*/
unsigned long rb_subtree_gap;
/* Second cache line starts here. */
struct mm_struct *vm_mm; /* The address space we belong to. */
pgprot_t vm_page_prot; /* Access permissions of this VMA. */
unsigned long vm_flags; /* Flags, see mm.h. */
/*
* For areas with an address space and backing store,
* linkage into the address_space->i_mmap interval tree.
*/
struct {
struct rb_node rb;
unsigned long rb_subtree_last;
} shared;
/*
* A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
* list, after a COW of one of the file pages. A MAP_SHARED vma
* can only be in the i_mmap tree. An anonymous MAP_PRIVATE, stack
* or brk vma (with NULL file) can only be in an anon_vma list.
*/
struct list_head anon_vma_chain; /* Serialized by mmap_sem &
* page_table_lock */
struct anon_vma *anon_vma; /* Serialized by page_table_lock */
/* Function pointers to deal with this struct. */
const struct vm_operations_struct *vm_ops;
/* Information about our backing store: */
unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE
units */
struct file * vm_file; /* File we map to (can be NULL). */
void * vm_private_data; /* was vm_pte (shared mem) */
#ifndef CONFIG_MMU
struct vm_region *vm_region; /* NOMMU mapping region */
#endif
#ifdef CONFIG_NUMA
struct mempolicy *vm_policy; /* NUMA policy for the VMA */
#endif
struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
};
