linux內存描述符mm_struct

struct mm_struct
{
    struct vm_area_struct *mmap;     //list of VMA
    rb_root_t mm_rb;                     //指向vma段紅黑樹的指針
    struct vm_area_struct *mmap_cache;   //last find_vma result  存儲上一次查詢的操作的結果
    pgd_t *pgd;                            //進程頁目錄的起始地址
    atomic_t mm_users;                    //how many users with user space
    atomic_t mm_count;                    //how many reference to "struct mm_struct"
    int map_count;                        //Number of VMA
    struct rw_semaphore mmap_sem;        //對mmap操作的互赤信號量
    spinlock_t page_table_lock;            //Protects task page tables and mm->rss
    struct list_head mmlist;            //list of all active mm's. These are globally together off init_mm.mmlist,and are protected by mmlist_lock
    unsigned long start_code,end_code,start_data,end_data;
    unsigned long start_brk,brk,start_stack;
    unsigned long arg_start,arg_end,env_start,env_end;
    unsigned long rss,total_vm,locked_vm;     //rss進程內容駐留在物理內存的頁面地址
    unsigned long def_flags;
    unsigned long cpu_vm_mask;
    unsigned long swap_address;     //頁面換出過程用到交換空間地址

    unsigned dumpable:1;
    //Architecture-specific MM context
    mm_context_t context;                //存放着當前進程使用的段起始地址
};


struct vm_area_struct
{
    struct mm_struct *vm_mm;        //The address space we belong to
    unsigned long vm_start;            //our start address within vm_mm
    unsigned long vm_end;

    struct vm_area_struct *vm_next;

    pgprot_t vm_page_prot;            //Access permission of this VMA
    unsigned long vm_flags;

    rb_node_t vm_rb;                   //rb Tree

    struct vm_area_struct *vm_next_share;
    struct vm_area_struct *vm_pprev_share;

    struct vm_operations_struct *vm_ops; //Function pointer to deal with this struct

    unsigned long vm_pgoff;

    struct file *vm_file;
    unsigned long vm_raend;
    void *vm_private_data;
};


struct vm_operations_struct
{
    void (*open)(struct vm_area_struct *area);
    void (*close)(struct vm_area_struct *area);
    struct page *(*nopage)(struct vm_area_struct *area,unsigned long address,int unused);
};


typedef struct rb_node_s
{
    struct rb_node_s *rb_parent;
    int rb_color;
#define RB_RED 0
#define RB_BLACK 1
    struct rb_node_s *rb_right;
    struct rb_node_s *rb_left;
}rb_node_t;

typedef struct rb_root_s
{
    struct rb_node_s *rb_node;
}rb_root_t;

//在樹中，所有的vm_area_struct虛存段都作為樹的一個節點，節點中vm_rb的左指針rbleft指向相鄰的低地址虛存段，右指針rbright指向相鄰的高地址虛存段
//用於調整紅黑樹的平衡
static void __rb_rotate_left(rb_node_t *node,rb_root_t *root);
static void __rb_rotate_right(rb_node_t *node,rb_root_t *root);

//插入一個新節點
void rb_insert_color(rb_node_t *node,rb_root_t *root);
//刪除一個節點
static void __rb_erase_color(rb_node_t *node,rb_node *parent,rb_root_t *root);
//刪除后對剩余顏色的調整
void rb_erase(rb_node_t *node,rb_root_t *root);


//對給定的內存地址找到屬於哪一個內存區域
struct vm_area_struct *find_vma(struct mm_struct *mm,unsigned long addr)
{
    struct vm_area_struct *vma=NULL;

    if(mm)
    {
        vma=mm->mmap_cache;
        if(!(vma&&vma->vm_end>addr&&vma->start<=addr))
        {
            struct rb_node *rb_node;
            rb_node=mm->mm_rb.rb_node;
            vma=NULL;
            while(rb_node)
                {
                    struct vm_area_struct *vma_tmp;
                    
                    vma_tmp=rb_entry(rb_node,struct vm_area_struct,vm_rb);

                    if(vma_tmp->vm_end>addr)
                    {
                        vma=vma_tmp;
                        if(vma_tmp->vm_start<=addr)
                            break;
                        rb_node=rb_node->rb_left;
                    }
                    else
                        rb_node=rb_node->rb_right;
                }
            if(vma)
                mm->mmap_cache=vma;
        }
    }
    return vma;
}