task_nommu.c

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#include <linux/mm.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/fs_struct.h>
#include <linux/mount.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include "internal.h"

/*
 * Logic: we've got two memory sums for each process, "shared", and
 * "non-shared". Shared memory may get counted more than once, for
 * each process that owns it. Non-shared memory is counted
 * accurately.
 */
void task_mem(struct seq_file *m, struct mm_struct *mm)
{
    struct vm_area_struct *vma;
    struct vm_region *region;
    struct rb_node *p;
    unsigned long bytes = 0, sbytes = 0, slack = 0, size;
        
    down_read(&mm->mmap_sem);
    for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
        vma = rb_entry(p, struct vm_area_struct, vm_rb);

        bytes += kobjsize(vma);

        region = vma->vm_region;
        if (region) {
            size = kobjsize(region);
            size += region->vm_end - region->vm_start;
        } else {
            size = vma->vm_end - vma->vm_start;
        }

        if (atomic_read(&mm->mm_count) > 1 ||
            vma->vm_flags & VM_MAYSHARE) {
            sbytes += size;
        } else {
            bytes += size;
            if (region)
                slack = region->vm_end - vma->vm_end;
        }
    }

    if (atomic_read(&mm->mm_count) > 1)
        sbytes += kobjsize(mm);
    else
        bytes += kobjsize(mm);
    
    if (current->fs && current->fs->users > 1)
        sbytes += kobjsize(current->fs);
    else
        bytes += kobjsize(current->fs);

    if (current->files && atomic_read(&current->files->count) > 1)
        sbytes += kobjsize(current->files);
    else
        bytes += kobjsize(current->files);

    if (current->sighand && atomic_read(&current->sighand->count) > 1)
        sbytes += kobjsize(current->sighand);
    else
        bytes += kobjsize(current->sighand);

    bytes += kobjsize(current); /* includes kernel stack */

    seq_printf(m,
        "Mem:\t%8lu bytes\n"
        "Slack:\t%8lu bytes\n"
        "Shared:\t%8lu bytes\n",
        bytes, slack, sbytes);

    up_read(&mm->mmap_sem);
}

unsigned long task_vsize(struct mm_struct *mm)
{
    struct vm_area_struct *vma;
    struct rb_node *p;
    unsigned long vsize = 0;

    down_read(&mm->mmap_sem);
    for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
        vma = rb_entry(p, struct vm_area_struct, vm_rb);
        vsize += vma->vm_end - vma->vm_start;
    }
    up_read(&mm->mmap_sem);
    return vsize;
}

unsigned long task_statm(struct mm_struct *mm,
             unsigned long *shared, unsigned long *text,
             unsigned long *data, unsigned long *resident)
{
    struct vm_area_struct *vma;
    struct vm_region *region;
    struct rb_node *p;
    unsigned long size = kobjsize(mm);

    down_read(&mm->mmap_sem);
    for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
        vma = rb_entry(p, struct vm_area_struct, vm_rb);
        size += kobjsize(vma);
        region = vma->vm_region;
        if (region) {
            size += kobjsize(region);
            size += region->vm_end - region->vm_start;
        }
    }

    *text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
        >> PAGE_SHIFT;
    *data = (PAGE_ALIGN(mm->start_stack) - (mm->start_data & PAGE_MASK))
        >> PAGE_SHIFT;
    up_read(&mm->mmap_sem);
    size >>= PAGE_SHIFT;
    size += *text + *data;
    *resident = size;
    return size;
}

static void pad_len_spaces(struct seq_file *m, int len)
{
    len = 25 + sizeof(void*) * 6 - len;
    if (len < 1)
        len = 1;
    seq_printf(m, "%*c", len, ' ');
}

/*
 * display a single VMA to a sequenced file
 */
static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
              int is_pid)
{
    struct mm_struct *mm = vma->vm_mm;
    struct proc_maps_private *priv = m->private;
    unsigned long ino = 0;
    struct file *file;
    dev_t dev = 0;
    int flags, len;
    unsigned long long pgoff = 0;

    flags = vma->vm_flags;
    file = vma->vm_file;

    if (file) {
        struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
        dev = inode->i_sb->s_dev;
        ino = inode->i_ino;
        pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
    }

    seq_printf(m,
           "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
           vma->vm_start,
           vma->vm_end,
           flags & VM_READ ? 'r' : '-',
           flags & VM_WRITE ? 'w' : '-',
           flags & VM_EXEC ? 'x' : '-',
           flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
           pgoff,
           MAJOR(dev), MINOR(dev), ino, &len);

    if (file) {
        pad_len_spaces(m, len);
        seq_path(m, &file->f_path, "");
    } else if (mm) {
        pid_t tid = vm_is_stack(priv->task, vma, is_pid);

        if (tid != 0) {
            pad_len_spaces(m, len);
            /*
             * Thread stack in /proc/PID/task/TID/maps or
             * the main process stack.
             */
            if (!is_pid || (vma->vm_start <= mm->start_stack &&
                vma->vm_end >= mm->start_stack))
                seq_printf(m, "[stack]");
            else
                seq_printf(m, "[stack:%d]", tid);
        }
    }

    seq_putc(m, '\n');
    return 0;
}

/*
 * display mapping lines for a particular process's /proc/pid/maps
 */
static int show_map(struct seq_file *m, void *_p, int is_pid)
{
    struct rb_node *p = _p;

    return nommu_vma_show(m, rb_entry(p, struct vm_area_struct, vm_rb),
                  is_pid);
}

static int show_pid_map(struct seq_file *m, void *_p)
{
    return show_map(m, _p, 1);
}

static int show_tid_map(struct seq_file *m, void *_p)
{
    return show_map(m, _p, 0);
}

static void *m_start(struct seq_file *m, loff_t *pos)
{
    struct proc_maps_private *priv = m->private;
    struct mm_struct *mm;
    struct rb_node *p;
    loff_t n = *pos;

    /* pin the task and mm whilst we play with them */
    priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
    if (!priv->task)
        return ERR_PTR(-ESRCH);

    mm = mm_access(priv->task, PTRACE_MODE_READ);
    if (!mm || IS_ERR(mm)) {
        put_task_struct(priv->task);
        priv->task = NULL;
        return mm;
    }
    down_read(&mm->mmap_sem);

    /* start from the Nth VMA */
    for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
        if (n-- == 0)
            return p;
    return NULL;
}

static void m_stop(struct seq_file *m, void *_vml)
{
    struct proc_maps_private *priv = m->private;

    if (priv->task) {
        struct mm_struct *mm = priv->task->mm;
        up_read(&mm->mmap_sem);
        mmput(mm);
        put_task_struct(priv->task);
    }
}

static void *m_next(struct seq_file *m, void *_p, loff_t *pos)
{
    struct rb_node *p = _p;

    (*pos)++;
    return p ? rb_next(p) : NULL;
}

static const struct seq_operations proc_pid_maps_ops = {
    .start  = m_start,
    .next   = m_next,
    .stop   = m_stop,
    .show   = show_pid_map
};

static const struct seq_operations proc_tid_maps_ops = {
    .start  = m_start,
    .next   = m_next,
    .stop   = m_stop,
    .show   = show_tid_map
};

static int maps_open(struct inode *inode, struct file *file,
             const struct seq_operations *ops)
{
    struct proc_maps_private *priv;
    int ret = -ENOMEM;

    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    if (priv) {
        priv->pid = proc_pid(inode);
        ret = seq_open(file, ops);
        if (!ret) {
            struct seq_file *m = file->private_data;
            m->private = priv;
        } else {
            kfree(priv);
        }
    }
    return ret;
}

static int pid_maps_open(struct inode *inode, struct file *file)
{
    return maps_open(inode, file, &proc_pid_maps_ops);
}

static int tid_maps_open(struct inode *inode, struct file *file)
{
    return maps_open(inode, file, &proc_tid_maps_ops);
}

const struct file_operations proc_pid_maps_operations = {
    .open       = pid_maps_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release_private,
};

const struct file_operations proc_tid_maps_operations = {
    .open       = tid_maps_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release_private,
};