《深入理解Linux内核》笔记9 - 进程地址空间

// include/linux/sched.h
struct task_struct
{
    /*...*/
	struct mm_struct		*mm;	// 内核线程为NULL
	struct mm_struct		*active_mm;
    /*...*/
}

struct mm_struct {
	struct vm_area_struct * mmap;		/* list of VMAs */
	struct rb_root mm_rb;               /* red-black tree root of VMAs */
	struct vm_area_struct * mmap_cache;	/* last find_vma result */
	unsigned long (*get_unmapped_area) (struct file *filp,
				unsigned long addr, unsigned long len,
				unsigned long pgoff, unsigned long flags);  /* 搜索有效地址区间的方法 */
	void (*unmap_area) (struct vm_area_struct *area);       /* 释放线性区的方法 */
	unsigned long mmap_base;		/* 第一个匿名线性区或文件内存映射的地址 */
	unsigned long free_area_cache;		/* 内核从这个地址开始搜索空闲区间 */
	pgd_t * pgd;    // 页全局目录指针
	atomic_t mm_users;			/* How many users with user space? */
	atomic_t mm_count;			/* How many references to "struct mm_struct" (users count as 1) */
	int map_count;				/* number of VMAs */
	struct rw_semaphore mmap_sem;
	spinlock_t page_table_lock;		/* Protects page tables, mm->rss, mm->anon_rss */

	struct list_head mmlist;		/* List of maybe swapped mm's.  These are globally strung
						 * 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, anon_rss, total_vm, locked_vm, shared_vm;
	unsigned long exec_vm, stack_vm, reserved_vm, def_flags, nr_ptes;

	unsigned long saved_auxv[42]; /* for /proc/PID/auxv */

	unsigned dumpable:1;
	cpumask_t cpu_vm_mask;

	/* Architecture-specific MM context */
	mm_context_t context;

	/* Token based thrashing protection. */
	unsigned long swap_token_time;
	char recent_pagein;

	/* coredumping support */
	int core_waiters;
	struct completion *core_startup_done, core_done;

	/* aio bits */
	rwlock_t		ioctx_list_lock;
	struct kioctx		*ioctx_list;

	struct kioctx		default_kioctx;

	unsigned long hiwater_rss;	/* High-water RSS usage */
	unsigned long hiwater_vm;	/* High-water virtual memory usage */
};

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;		/* 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;

	pgprot_t vm_page_prot;		/* Access permissions of this VMA. */
	unsigned long vm_flags;		/* Flags, listed below. */

	struct rb_node vm_rb;

	/*
	 * For areas with an address space and backing store,
	 * linkage into the address_space->i_mmap prio tree, or
	 * linkage to the list of like vmas hanging off its node, or
	 * linkage of vma in the address_space->i_mmap_nonlinear list.
	 */
	union {
		struct {
			struct list_head list;
			void *parent;	/* aligns with prio_tree_node parent */
			struct vm_area_struct *head;
		} vm_set;

		struct raw_prio_tree_node prio_tree_node;
	} 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_node;	/* Serialized by anon_vma->lock */
	struct anon_vma *anon_vma;	/* Serialized by page_table_lock */

	/* Function pointers to deal with this struct. */
	struct vm_operations_struct * vm_ops;

	/* Information about our backing store: */
	unsigned long vm_pgoff;		/* Offset (within vm_file) in PAGE_SIZE
					   units, *not* PAGE_CACHE_SIZE */
	struct file * vm_file;		/* File we map to (can be NULL). */
	void * vm_private_data;		/* was vm_pte (shared mem) */
	unsigned long vm_truncate_count;/* truncate_count or restart_addr */

#ifndef CONFIG_MMU
	atomic_t vm_usage;		/* refcount (VMAs shared if !MMU) */
#endif
#ifdef CONFIG_NUMA
	struct mempolicy *vm_policy;	/* NUMA policy for the VMA */
#endif
};

// include/linux/mm.h
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 *type);
	int (*populate)(struct vm_area_struct * area, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock);
#ifdef CONFIG_NUMA
	int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
	struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
					unsigned long addr);
#endif
};

// arch/i386/kernel/traps.c
// 注册中断和异常处理函数
void __init trap_init(void)
{
    // ...
    set_intr_gate(14,&page_fault);
    // ...
}

// arch/i386/mm/fault.c
// pt_regs是异常发生时的寄存器的值
fastcall void do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
	// ...
}