fs/proc/task_nommu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/mm.h>
   4 #include <linux/file.h>
   5 #include <linux/fdtable.h>
   6 #include <linux/fs_struct.h>
   7 #include <linux/mount.h>
   8 #include <linux/ptrace.h>
   9 #include <linux/slab.h>
  10 #include <linux/seq_file.h>
  11 #include <linux/sched/mm.h>
  12
  13 #include "internal.h"
  14
  15 /*
  16  * Logic: we've got two memory sums for each process, "shared", and
  17  * "non-shared". Shared memory may get counted more than once, for
  18  * each process that owns it. Non-shared memory is counted
  19  * accurately.
  20  */
  21 void task_mem(struct seq_file *m, struct mm_struct *mm)
  22 {
  23         struct vm_area_struct *vma;
  24         struct vm_region *region;
  25         struct rb_node *p;
  26         unsigned long bytes = 0, sbytes = 0, slack = 0, size;
  27
  28         mmap_read_lock(mm);
  29         for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
  30                 vma = rb_entry(p, struct vm_area_struct, vm_rb);
  31
  32                 bytes += kobjsize(vma);
  33
  34                 region = vma->vm_region;
  35                 if (region) {
  36                         size = kobjsize(region);
  37                         size += region->vm_end - region->vm_start;
  38                 } else {
  39                         size = vma->vm_end - vma->vm_start;
  40                 }
  41
  42                 if (atomic_read(&mm->mm_count) > 1 ||
  43                     vma->vm_flags & VM_MAYSHARE) {
  44                         sbytes += size;
  45                 } else {
  46                         bytes += size;
  47                         if (region)
  48                                 slack = region->vm_end - vma->vm_end;
  49                 }
  50         }
  51
  52         if (atomic_read(&mm->mm_count) > 1)
  53                 sbytes += kobjsize(mm);
  54         else
  55                 bytes += kobjsize(mm);
  56
  57         if (current->fs && current->fs->users > 1)
  58                 sbytes += kobjsize(current->fs);
  59         else
  60                 bytes += kobjsize(current->fs);
  61
  62         if (current->files && atomic_read(&current->files->count) > 1)
  63                 sbytes += kobjsize(current->files);
  64         else
  65                 bytes += kobjsize(current->files);
  66
  67         if (current->sighand && refcount_read(&current->sighand->count) > 1)
  68                 sbytes += kobjsize(current->sighand);
  69         else
  70                 bytes += kobjsize(current->sighand);
  71
  72         bytes += kobjsize(current); /* includes kernel stack */
  73
  74         seq_printf(m,
  75                 "Mem:\t%8lu bytes\n"
  76                 "Slack:\t%8lu bytes\n"
  77                 "Shared:\t%8lu bytes\n",
  78                 bytes, slack, sbytes);
  79
  80         mmap_read_unlock(mm);
  81 }
  82
  83 unsigned long task_vsize(struct mm_struct *mm)
  84 {
  85         struct vm_area_struct *vma;
  86         struct rb_node *p;
  87         unsigned long vsize = 0;
  88
  89         mmap_read_lock(mm);
  90         for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
  91                 vma = rb_entry(p, struct vm_area_struct, vm_rb);
  92                 vsize += vma->vm_end - vma->vm_start;
  93         }
  94         mmap_read_unlock(mm);
  95         return vsize;
  96 }
  97
  98 unsigned long task_statm(struct mm_struct *mm,
  99                          unsigned long *shared, unsigned long *text,
 100                          unsigned long *data, unsigned long *resident)
 101 {
 102         struct vm_area_struct *vma;
 103         struct vm_region *region;
 104         struct rb_node *p;
 105         unsigned long size = kobjsize(mm);
 106
 107         mmap_read_lock(mm);
 108         for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
 109                 vma = rb_entry(p, struct vm_area_struct, vm_rb);
 110                 size += kobjsize(vma);
 111                 region = vma->vm_region;
 112                 if (region) {
 113                         size += kobjsize(region);
 114                         size += region->vm_end - region->vm_start;
 115                 }
 116         }
 117
 118         *text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
 119                 >> PAGE_SHIFT;
 120         *data = (PAGE_ALIGN(mm->start_stack) - (mm->start_data & PAGE_MASK))
 121                 >> PAGE_SHIFT;
 122         mmap_read_unlock(mm);
 123         size >>= PAGE_SHIFT;
 124         size += *text + *data;
 125         *resident = size;
 126         return size;
 127 }
 128
 129 static int is_stack(struct vm_area_struct *vma)
 130 {
 131         struct mm_struct *mm = vma->vm_mm;
 132
 133         /*
 134          * We make no effort to guess what a given thread considers to be
 135          * its "stack".  It's not even well-defined for programs written
 136          * languages like Go.
 137          */
 138         return vma->vm_start <= mm->start_stack &&
 139                 vma->vm_end >= mm->start_stack;
 140 }
 141
 142 /*
 143  * display a single VMA to a sequenced file
 144  */
 145 static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
 146 {
 147         struct mm_struct *mm = vma->vm_mm;
 148         unsigned long ino = 0;
 149         struct file *file;
 150         dev_t dev = 0;
 151         int flags;
 152         unsigned long long pgoff = 0;
 153
 154         flags = vma->vm_flags;
 155         file = vma->vm_file;
 156
 157         if (file) {
 158                 struct inode *inode = file_inode(vma->vm_file);
 159                 dev = inode->i_sb->s_dev;
 160                 ino = inode->i_ino;
 161                 pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
 162         }
 163
 164         seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
 165         seq_printf(m,
 166                    "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 167                    vma->vm_start,
 168                    vma->vm_end,
 169                    flags & VM_READ ? 'r' : '-',
 170                    flags & VM_WRITE ? 'w' : '-',
 171                    flags & VM_EXEC ? 'x' : '-',
 172                    flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
 173                    pgoff,
 174                    MAJOR(dev), MINOR(dev), ino);
 175
 176         if (file) {
 177                 seq_pad(m, ' ');
 178                 seq_file_path(m, file, "");
 179         } else if (mm && is_stack(vma)) {
 180                 seq_pad(m, ' ');
 181                 seq_puts(m, "[stack]");
 182         }
 183
 184         seq_putc(m, '\n');
 185         return 0;
 186 }
 187
 188 /*
 189  * display mapping lines for a particular process's /proc/pid/maps
 190  */
 191 static int show_map(struct seq_file *m, void *_p)
 192 {
 193         struct rb_node *p = _p;
 194
 195         return nommu_vma_show(m, rb_entry(p, struct vm_area_struct, vm_rb));
 196 }
 197
 198 static void *m_start(struct seq_file *m, loff_t *pos)
 199 {
 200         struct proc_maps_private *priv = m->private;
 201         struct mm_struct *mm;
 202         struct rb_node *p;
 203         loff_t n = *pos;
 204
 205         /* pin the task and mm whilst we play with them */
 206         priv->task = get_proc_task(priv->inode);
 207         if (!priv->task)
 208                 return ERR_PTR(-ESRCH);
 209
 210         mm = priv->mm;
 211         if (!mm || !mmget_not_zero(mm))
 212                 return NULL;
 213
 214         if (mmap_read_lock_killable(mm)) {
 215                 mmput(mm);
 216                 return ERR_PTR(-EINTR);
 217         }
 218
 219         /* start from the Nth VMA */
 220         for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
 221                 if (n-- == 0)
 222                         return p;
 223
 224         mmap_read_unlock(mm);
 225         mmput(mm);
 226         return NULL;
 227 }
 228
 229 static void m_stop(struct seq_file *m, void *_vml)
 230 {
 231         struct proc_maps_private *priv = m->private;
 232
 233         if (!IS_ERR_OR_NULL(_vml)) {
 234                 mmap_read_unlock(priv->mm);
 235                 mmput(priv->mm);
 236         }
 237         if (priv->task) {
 238                 put_task_struct(priv->task);
 239                 priv->task = NULL;
 240         }
 241 }
 242
 243 static void *m_next(struct seq_file *m, void *_p, loff_t *pos)
 244 {
 245         struct rb_node *p = _p;
 246
 247         (*pos)++;
 248         return p ? rb_next(p) : NULL;
 249 }
 250
 251 static const struct seq_operations proc_pid_maps_ops = {
 252         .start  = m_start,
 253         .next   = m_next,
 254         .stop   = m_stop,
 255         .show   = show_map
 256 };
 257
 258 static int maps_open(struct inode *inode, struct file *file,
 259                      const struct seq_operations *ops)
 260 {
 261         struct proc_maps_private *priv;
 262
 263         priv = __seq_open_private(file, ops, sizeof(*priv));
 264         if (!priv)
 265                 return -ENOMEM;
 266
 267         priv->inode = inode;
 268         priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
 269         if (IS_ERR(priv->mm)) {
 270                 int err = PTR_ERR(priv->mm);
 271
 272                 seq_release_private(inode, file);
 273                 return err;
 274         }
 275
 276         return 0;
 277 }
 278
 279
 280 static int map_release(struct inode *inode, struct file *file)
 281 {
 282         struct seq_file *seq = file->private_data;
 283         struct proc_maps_private *priv = seq->private;
 284
 285         if (priv->mm)
 286                 mmdrop(priv->mm);
 287
 288         return seq_release_private(inode, file);
 289 }
 290
 291 static int pid_maps_open(struct inode *inode, struct file *file)
 292 {
 293         return maps_open(inode, file, &proc_pid_maps_ops);
 294 }
 295
 296 const struct file_operations proc_pid_maps_operations = {
 297         .open           = pid_maps_open,
 298         .read           = seq_read,
 299         .llseek         = seq_lseek,
 300         .release        = map_release,
 301 };
 302