root/fs/proc/mem.c

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DEFINITIONS

This source file includes following definitions.
  1. check_range
  2. mem_read
  3. mem_write
  4. mem_lseek
  5. mem_mmap

   1 /*
   2  *  linux/fs/proc/mem.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <linux/types.h>
   8 #include <linux/errno.h>
   9 #include <linux/sched.h>
  10 #include <linux/kernel.h>
  11 #include <linux/mm.h>
  12 
  13 #include <asm/page.h>
  14 #include <asm/segment.h>
  15 #include <asm/io.h>
  16 #include <asm/pgtable.h>
  17 
  18 /*
  19  * mem_write isn't really a good idea right now. It needs
  20  * to check a lot more: if the process we try to write to 
  21  * dies in the middle right now, mem_write will overwrite
  22  * kernel memory.. This disables it altogether.
  23  */
  24 #define mem_write NULL
  25 
  26 static int check_range(struct task_struct * tsk, unsigned long addr, int count)
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  27 {
  28         struct vm_area_struct *vma;
  29         int retval;
  30 
  31         vma = find_vma(tsk, addr);
  32         if (!vma)
  33                 return -EACCES;
  34         if (vma->vm_start > addr)
  35                 return -EACCES;
  36         if (!(vma->vm_flags & VM_READ))
  37                 return -EACCES;
  38         while ((retval = vma->vm_end - addr) < count) {
  39                 struct vm_area_struct *next = vma->vm_next;
  40                 if (!next)
  41                         break;
  42                 if (vma->vm_end != next->vm_start)
  43                         break;
  44                 if (!(next->vm_flags & VM_READ))
  45                         break;
  46                 vma = next;
  47         }
  48         if (retval > count)
  49                 retval = count;
  50         return retval;
  51 }
  52 
  53 static int mem_read(struct inode * inode, struct file * file,char * buf, int count)
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  54 {
  55         pgd_t *page_dir;
  56         pmd_t *page_middle;
  57         pte_t pte;
  58         char * page;
  59         struct task_struct * tsk;
  60         unsigned long addr, pid;
  61         char *tmp;
  62         int i;
  63 
  64         if (count < 0)
  65                 return -EINVAL;
  66         pid = inode->i_ino;
  67         pid >>= 16;
  68         if (pid != current->pid)
  69                 return -EACCES;
  70         tsk = current;
  71         addr = file->f_pos;
  72         count = check_range(tsk, addr, count);
  73         if (count < 0)
  74                 return count;
  75         tmp = buf;
  76         while (count > 0) {
  77                 if (current->signal & ~current->blocked)
  78                         break;
  79                 page_dir = pgd_offset(tsk->mm,addr);
  80                 if (pgd_none(*page_dir))
  81                         break;
  82                 if (pgd_bad(*page_dir)) {
  83                         printk("Bad page dir entry %08lx\n", pgd_val(*page_dir));
  84                         pgd_clear(page_dir);
  85                         break;
  86                 }
  87                 page_middle = pmd_offset(page_dir,addr);
  88                 if (pmd_none(*page_middle))
  89                         break;
  90                 if (pmd_bad(*page_middle)) {
  91                         printk("Bad page middle entry %08lx\n", pmd_val(*page_middle));
  92                         pmd_clear(page_middle);
  93                         break;
  94                 }
  95                 pte = *pte_offset(page_middle,addr);
  96                 if (!pte_present(pte))
  97                         break;
  98                 page = (char *) pte_page(pte) + (addr & ~PAGE_MASK);
  99                 i = PAGE_SIZE-(addr & ~PAGE_MASK);
 100                 if (i > count)
 101                         i = count;
 102                 memcpy_tofs(tmp, page, i);
 103                 addr += i;
 104                 tmp += i;
 105                 count -= i;
 106         }
 107         file->f_pos = addr;
 108         return tmp-buf;
 109 }
 110 
 111 #ifndef mem_write
 112 
 113 static int mem_write(struct inode * inode, struct file * file,char * buf, int count)
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 114 {
 115         pgd_t *page_dir;
 116         pmd_t *page_middle;
 117         pte_t pte;
 118         char * page;
 119         struct task_struct * tsk;
 120         unsigned long addr, pid;
 121         char *tmp;
 122         int i;
 123 
 124         if (count < 0)
 125                 return -EINVAL;
 126         addr = file->f_pos;
 127         pid = inode->i_ino;
 128         pid >>= 16;
 129         if (pid != current->pid)
 130                 return -EACCES;
 131         tsk = current;
 132         tmp = buf;
 133         while (count > 0) {
 134                 if (current->signal & ~current->blocked)
 135                         break;
 136                 page_dir = pgd_offset(tsk,addr);
 137                 if (pgd_none(*page_dir))
 138                         break;
 139                 if (pgd_bad(*page_dir)) {
 140                         printk("Bad page dir entry %08lx\n", pgd_val(*page_dir));
 141                         pgd_clear(page_dir);
 142                         break;
 143                 }
 144                 page_middle = pmd_offset(page_dir,addr);
 145                 if (pmd_none(*page_middle))
 146                         break;
 147                 if (pmd_bad(*page_middle)) {
 148                         printk("Bad page middle entry %08lx\n", pmd_val(*page_middle));
 149                         pmd_clear(page_middle);
 150                         break;
 151                 }
 152                 pte = *pte_offset(page_middle,addr);
 153                 if (!pte_present(pte))
 154                         break;
 155                 if (!pte_write(pte))
 156                         break;
 157                 page = (char *) pte_page(pte) + (addr & ~PAGE_MASK);
 158                 i = PAGE_SIZE-(addr & ~PAGE_MASK);
 159                 if (i > count)
 160                         i = count;
 161                 memcpy_fromfs(page, tmp, i);
 162                 addr += i;
 163                 tmp += i;
 164                 count -= i;
 165         }
 166         file->f_pos = addr;
 167         if (tmp != buf)
 168                 return tmp-buf;
 169         if (current->signal & ~current->blocked)
 170                 return -ERESTARTSYS;
 171         return 0;
 172 }
 173 
 174 #endif
 175 
 176 static int mem_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
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 177 {
 178         switch (orig) {
 179                 case 0:
 180                         file->f_pos = offset;
 181                         return file->f_pos;
 182                 case 1:
 183                         file->f_pos += offset;
 184                         return file->f_pos;
 185                 default:
 186                         return -EINVAL;
 187         }
 188 }
 189 
 190 /*
 191  * This isn't really reliable by any means..
 192  */
 193 int mem_mmap(struct inode * inode, struct file * file,
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 194              struct vm_area_struct * vma)
 195 {
 196         struct task_struct *tsk;
 197         pgd_t *src_dir, *dest_dir;
 198         pmd_t *src_middle, *dest_middle;
 199         pte_t *src_table, *dest_table;
 200         unsigned long stmp, dtmp;
 201         struct vm_area_struct *src_vma = NULL;
 202         int i;
 203 
 204         /* Get the source's task information */
 205 
 206         tsk = NULL;
 207         for (i = 1 ; i < NR_TASKS ; i++)
 208                 if (task[i] && task[i]->pid == (inode->i_ino >> 16)) {
 209                         tsk = task[i];
 210                         break;
 211                 }
 212 
 213         if (!tsk)
 214                 return -EACCES;
 215 
 216         /* Ensure that we have a valid source area.  (Has to be mmap'ed and
 217          have valid page information.)  We can't map shared memory at the
 218          moment because working out the vm_area_struct & nattach stuff isn't
 219          worth it. */
 220 
 221         src_vma = tsk->mm->mmap;
 222         stmp = vma->vm_offset;
 223         while (stmp < vma->vm_offset + (vma->vm_end - vma->vm_start)) {
 224                 while (src_vma && stmp > src_vma->vm_end)
 225                         src_vma = src_vma->vm_next;
 226                 if (!src_vma || (src_vma->vm_flags & VM_SHM))
 227                         return -EINVAL;
 228 
 229                 src_dir = pgd_offset(tsk->mm, stmp);
 230                 if (pgd_none(*src_dir))
 231                         return -EINVAL;
 232                 if (pgd_bad(*src_dir)) {
 233                         printk("Bad source page dir entry %08lx\n", pgd_val(*src_dir));
 234                         return -EINVAL;
 235                 }
 236                 src_middle = pmd_offset(src_dir, stmp);
 237                 if (pmd_none(*src_middle))
 238                         return -EINVAL;
 239                 if (pmd_bad(*src_middle)) {
 240                         printk("Bad source page middle entry %08lx\n", pmd_val(*src_middle));
 241                         return -EINVAL;
 242                 }
 243                 src_table = pte_offset(src_middle, stmp);
 244                 if (pte_none(*src_table))
 245                         return -EINVAL;
 246 
 247                 if (stmp < src_vma->vm_start) {
 248                         if (!(src_vma->vm_flags & VM_GROWSDOWN))
 249                                 return -EINVAL;
 250                         if (src_vma->vm_end - stmp > current->rlim[RLIMIT_STACK].rlim_cur)
 251                                 return -EINVAL;
 252                 }
 253                 stmp += PAGE_SIZE;
 254         }
 255 
 256         src_vma = tsk->mm->mmap;
 257         stmp    = vma->vm_offset;
 258         dtmp    = vma->vm_start;
 259 
 260         flush_cache_range(vma->vm_mm, vma->vm_start, vma->vm_end);
 261         flush_cache_range(src_vma->vm_mm, src_vma->vm_start, src_vma->vm_end);
 262         while (dtmp < vma->vm_end) {
 263                 while (src_vma && stmp > src_vma->vm_end)
 264                         src_vma = src_vma->vm_next;
 265 
 266                 src_dir = pgd_offset(tsk->mm, stmp);
 267                 src_middle = pmd_offset(src_dir, stmp);
 268                 src_table = pte_offset(src_middle, stmp);
 269 
 270                 dest_dir = pgd_offset(current->mm, dtmp);
 271                 dest_middle = pmd_alloc(dest_dir, dtmp);
 272                 if (!dest_middle)
 273                         return -ENOMEM;
 274                 dest_table = pte_alloc(dest_middle, dtmp);
 275                 if (!dest_table)
 276                         return -ENOMEM;
 277 
 278                 if (!pte_present(*src_table))
 279                         do_no_page(tsk, src_vma, stmp, 1);
 280 
 281                 if ((vma->vm_flags & VM_WRITE) && !pte_write(*src_table))
 282                         do_wp_page(tsk, src_vma, stmp, 1);
 283 
 284                 set_pte(src_table, pte_mkdirty(*src_table));
 285                 set_pte(dest_table, *src_table);
 286                 mem_map[MAP_NR(pte_page(*src_table))].count++;
 287 
 288                 stmp += PAGE_SIZE;
 289                 dtmp += PAGE_SIZE;
 290         }
 291 
 292         flush_tlb_range(vma->vm_mm, vma->vm_start, vma->vm_end);
 293         flush_tlb_range(src_vma->vm_mm, src_vma->vm_start, src_vma->vm_end);
 294         return 0;
 295 }
 296 
 297 static struct file_operations proc_mem_operations = {
 298         mem_lseek,
 299         mem_read,
 300         mem_write,
 301         NULL,           /* mem_readdir */
 302         NULL,           /* mem_select */
 303         NULL,           /* mem_ioctl */
 304         mem_mmap,       /* mmap */
 305         NULL,           /* no special open code */
 306         NULL,           /* no special release code */
 307         NULL            /* can't fsync */
 308 };
 309 
 310 struct inode_operations proc_mem_inode_operations = {
 311         &proc_mem_operations,   /* default base directory file-ops */
 312         NULL,                   /* create */
 313         NULL,                   /* lookup */
 314         NULL,                   /* link */
 315         NULL,                   /* unlink */
 316         NULL,                   /* symlink */
 317         NULL,                   /* mkdir */
 318         NULL,                   /* rmdir */
 319         NULL,                   /* mknod */
 320         NULL,                   /* rename */
 321         NULL,                   /* readlink */
 322         NULL,                   /* follow_link */
 323         NULL,                   /* readpage */
 324         NULL,                   /* writepage */
 325         NULL,                   /* bmap */
 326         NULL,                   /* truncate */
 327         NULL                    /* permission */
 328 };

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