mm_types.h

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#ifndef _LINUX_MM_TYPES_H
#define _LINUX_MM_TYPES_H

#include <linux/auxvec.h>
#include <linux/types.h>
#include <linux/threads.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include <linux/rwsem.h>
#include <linux/completion.h>
#include <linux/cpumask.h>
#include <linux/page-debug-flags.h>
#include <linux/uprobes.h>
#include <asm/page.h>
#include <asm/mmu.h>

#ifndef AT_VECTOR_SIZE_ARCH
#define AT_VECTOR_SIZE_ARCH 0
#endif
#define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))

struct address_space;

#define USE_SPLIT_PTLOCKS   (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)

/*
 * Each physical page in the system has a struct page associated with
 * it to keep track of whatever it is we are using the page for at the
 * moment. Note that we have no way to track which tasks are using
 * a page, though if it is a pagecache page, rmap structures can tell us
 * who is mapping it.
 *
 * The objects in struct page are organized in double word blocks in
 * order to allows us to use atomic double word operations on portions
 * of struct page. That is currently only used by slub but the arrangement
 * allows the use of atomic double word operations on the flags/mapping
 * and lru list pointers also.
 */
struct page {
    /* First double word block */
    unsigned long flags;        /* Atomic flags, some possibly
                     * updated asynchronously */
    struct address_space *mapping;  /* If low bit clear, points to
                     * inode address_space, or NULL.
                     * If page mapped as anonymous
                     * memory, low bit is set, and
                     * it points to anon_vma object:
                     * see PAGE_MAPPING_ANON below.
                     */
    /* Second double word */
    struct {
        union {
            pgoff_t index;      /* Our offset within mapping. */
            void *freelist;     /* slub/slob first free object */
            bool pfmemalloc;    /* If set by the page allocator,
                         * ALLOC_NO_WATERMARKS was set
                         * and the low watermark was not
                         * met implying that the system
                         * is under some pressure. The
                         * caller should try ensure
                         * this page is only used to
                         * free other pages.
                         */
        };

        union {
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
            /* Used for cmpxchg_double in slub */
            unsigned long counters;
#else
            /*
             * Keep _count separate from slub cmpxchg_double data.
             * As the rest of the double word is protected by
             * slab_lock but _count is not.
             */
            unsigned counters;
#endif

            struct {

                union {
                    /*
                     * Count of ptes mapped in
                     * mms, to show when page is
                     * mapped & limit reverse map
                     * searches.
                     *
                     * Used also for tail pages
                     * refcounting instead of
                     * _count. Tail pages cannot
                     * be mapped and keeping the
                     * tail page _count zero at
                     * all times guarantees
                     * get_page_unless_zero() will
                     * never succeed on tail
                     * pages.
                     */
                    atomic_t _mapcount;

                    struct { /* SLUB */
                        unsigned inuse:16;
                        unsigned objects:15;
                        unsigned frozen:1;
                    };
                    int units;  /* SLOB */
                };
                atomic_t _count;        /* Usage count, see below. */
            };
        };
    };

    /* Third double word block */
    union {
        struct list_head lru;   /* Pageout list, eg. active_list
                     * protected by zone->lru_lock !
                     */
        struct {        /* slub per cpu partial pages */
            struct page *next;  /* Next partial slab */
#ifdef CONFIG_64BIT
            int pages;  /* Nr of partial slabs left */
            int pobjects;   /* Approximate # of objects */
#else
            short int pages;
            short int pobjects;
#endif
        };

        struct list_head list;  /* slobs list of pages */
        struct {        /* slab fields */
            struct kmem_cache *slab_cache;
            struct slab *slab_page;
        };
    };

    /* Remainder is not double word aligned */
    union {
        unsigned long private;      /* Mapping-private opaque data:
                         * usually used for buffer_heads
                         * if PagePrivate set; used for
                         * swp_entry_t if PageSwapCache;
                         * indicates order in the buddy
                         * system if PG_buddy is set.
                         */
#if USE_SPLIT_PTLOCKS
        spinlock_t ptl;
#endif
        struct kmem_cache *slab;    /* SLUB: Pointer to slab */
        struct page *first_page;    /* Compound tail pages */
    };

    /*
     * On machines where all RAM is mapped into kernel address space,
     * we can simply calculate the virtual address. On machines with
     * highmem some memory is mapped into kernel virtual memory
     * dynamically, so we need a place to store that address.
     * Note that this field could be 16 bits on x86 ... ;)
     *
     * Architectures with slow multiplication can define
     * WANT_PAGE_VIRTUAL in asm/page.h
     */
#if defined(WANT_PAGE_VIRTUAL)
    void *virtual;          /* Kernel virtual address (NULL if
                       not kmapped, ie. highmem) */
#endif /* WANT_PAGE_VIRTUAL */
#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS
    unsigned long debug_flags;  /* Use atomic bitops on this */
#endif

#ifdef CONFIG_KMEMCHECK
    /*
     * kmemcheck wants to track the status of each byte in a page; this
     * is a pointer to such a status block. NULL if not tracked.
     */
    void *shadow;
#endif
}
/*
 * The struct page can be forced to be double word aligned so that atomic ops
 * on double words work. The SLUB allocator can make use of such a feature.
 */
#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
    __aligned(2 * sizeof(unsigned long))
#endif
;

struct page_frag {
    struct page *page;
#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
    __u32 offset;
    __u32 size;
#else
    __u16 offset;
    __u16 size;
#endif
};

typedef unsigned long __nocast vm_flags_t;

/*
 * A region containing a mapping of a non-memory backed file under NOMMU
 * conditions.  These are held in a global tree and are pinned by the VMAs that
 * map parts of them.
 */
struct vm_region {
    struct rb_node  vm_rb;      /* link in global region tree */
    vm_flags_t  vm_flags;   /* VMA vm_flags */
    unsigned long   vm_start;   /* start address of region */
    unsigned long   vm_end;     /* region initialised to here */
    unsigned long   vm_top;     /* region allocated to here */
    unsigned long   vm_pgoff;   /* the offset in vm_file corresponding to vm_start */
    struct file *vm_file;   /* the backing file or NULL */

    int     vm_usage;   /* region usage count (access under nommu_region_sem) */
    bool        vm_icache_flushed : 1; /* true if the icache has been flushed for
                        * this region */
};

/*
 * 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 {
    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, *vm_prev;

    pgprot_t vm_page_prot;      /* Access permissions of this VMA. */
    unsigned long vm_flags;     /* Flags, see mm.h. */

    struct rb_node vm_rb;

    /*
     * For areas with an address space and backing store,
     * linkage into the address_space->i_mmap interval tree, or
     * linkage of vma in the address_space->i_mmap_nonlinear list.
     */
    union {
        struct {
            struct rb_node rb;
            unsigned long rb_subtree_last;
        } linear;
        struct list_head nonlinear;
    } 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, *not* PAGE_CACHE_SIZE */
    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 core_thread {
    struct task_struct *task;
    struct core_thread *next;
};

struct core_state {
    atomic_t nr_threads;
    struct core_thread dumper;
    struct completion startup;
};

enum {
    MM_FILEPAGES,
    MM_ANONPAGES,
    MM_SWAPENTS,
    NR_MM_COUNTERS
};

#if USE_SPLIT_PTLOCKS && defined(CONFIG_MMU)
#define SPLIT_RSS_COUNTING
/* per-thread cached information, */
struct task_rss_stat {
    int events; /* for synchronization threshold */
    int count[NR_MM_COUNTERS];
};
#endif /* USE_SPLIT_PTLOCKS */

struct mm_rss_stat {
    atomic_long_t count[NR_MM_COUNTERS];
};

struct mm_struct {
    struct vm_area_struct * mmap;       /* list of VMAs */
    struct rb_root mm_rb;
    struct vm_area_struct * mmap_cache; /* last find_vma result */
#ifdef CONFIG_MMU
    unsigned long (*get_unmapped_area) (struct file *filp,
                unsigned long addr, unsigned long len,
                unsigned long pgoff, unsigned long flags);
    void (*unmap_area) (struct mm_struct *mm, unsigned long addr);
#endif
    unsigned long mmap_base;        /* base of mmap area */
    unsigned long task_size;        /* size of task vm space */
    unsigned long cached_hole_size;     /* if non-zero, the largest hole below free_area_cache */
    unsigned long free_area_cache;      /* first hole of size cached_hole_size or larger */
    pgd_t * pgd;
    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 */

    spinlock_t page_table_lock;     /* Protects page tables and some counters */
    struct rw_semaphore mmap_sem;

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

    unsigned long total_vm;     /* Total pages mapped */
    unsigned long locked_vm;    /* Pages that have PG_mlocked set */
    unsigned long pinned_vm;    /* Refcount permanently increased */
    unsigned long shared_vm;    /* Shared pages (files) */
    unsigned long exec_vm;      /* VM_EXEC & ~VM_WRITE */
    unsigned long stack_vm;     /* VM_GROWSUP/DOWN */
    unsigned long def_flags;
    unsigned long nr_ptes;      /* Page table pages */
    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 saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */

    /*
     * Special counters, in some configurations protected by the
     * page_table_lock, in other configurations by being atomic.
     */
    struct mm_rss_stat rss_stat;

    struct linux_binfmt *binfmt;

    cpumask_var_t cpu_vm_mask_var;

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

    unsigned long flags; /* Must use atomic bitops to access the bits */

    struct core_state *core_state; /* coredumping support */
#ifdef CONFIG_AIO
    spinlock_t      ioctx_lock;
    struct hlist_head   ioctx_list;
#endif
#ifdef CONFIG_MM_OWNER
    /*
     * "owner" points to a task that is regarded as the canonical
     * user/owner of this mm. All of the following must be true in
     * order for it to be changed:
     *
     * current == mm->owner
     * current->mm != mm
     * new_owner->mm == mm
     * new_owner->alloc_lock is held
     */
    struct task_struct __rcu *owner;
#endif

    /* store ref to file /proc/<pid>/exe symlink points to */
    struct file *exe_file;
#ifdef CONFIG_MMU_NOTIFIER
    struct mmu_notifier_mm *mmu_notifier_mm;
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
    pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
#ifdef CONFIG_CPUMASK_OFFSTACK
    struct cpumask cpumask_allocation;
#endif
    struct uprobes_state uprobes_state;
};

static inline void mm_init_cpumask(struct mm_struct *mm)
{
#ifdef CONFIG_CPUMASK_OFFSTACK
    mm->cpu_vm_mask_var = &mm->cpumask_allocation;
#endif
}

/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
{
    return mm->cpu_vm_mask_var;
}

#endif /* _LINUX_MM_TYPES_H */