drivers/char/mem.c

   1 /*
   2  *  linux/drivers/char/mem.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  Added devfs support.
   7  *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
   8  *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/mm.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/slab.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/mman.h>
  17 #include <linux/random.h>
  18 #include <linux/init.h>
  19 #include <linux/raw.h>
  20 #include <linux/tty.h>
  21 #include <linux/capability.h>
  22 #include <linux/smp_lock.h>
  23 #include <linux/devfs_fs_kernel.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/device.h>
  26 #include <linux/highmem.h>
  27 #include <linux/crash_dump.h>
  28 #include <linux/backing-dev.h>
  29 #include <linux/bootmem.h>
  30 #include <linux/pipe_fs_i.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/io.h>
  34
  35 #ifdef CONFIG_IA64
  36 # include <linux/efi.h>
  37 #endif
  38
  39 static inline int range_is_allowed(unsigned long from, unsigned long to)
  40 {
  41         unsigned long cursor;
  42
  43         cursor = from >> PAGE_SHIFT;
  44         while ((cursor << PAGE_SHIFT) < to) {
  45                 if (!devmem_is_allowed(cursor)) {
  46                         printk ("Program %s tried to read /dev/mem between %lx->%lx.\n",
  47                                         current->comm, from, to);
  48                         return 0;
  49                 }
  50                 cursor++;
  51         }
  52         return 1;
  53 }
  54
  55 /*
  56  * Architectures vary in how they handle caching for addresses
  57  * outside of main memory.
  58  *
  59  */
  60 static inline int uncached_access(struct file *file, unsigned long addr)
  61 {
  62 #if defined(__i386__)
  63         /*
  64          * On the PPro and successors, the MTRRs are used to set
  65          * memory types for physical addresses outside main memory,
  66          * so blindly setting PCD or PWT on those pages is wrong.
  67          * For Pentiums and earlier, the surround logic should disable
  68          * caching for the high addresses through the KEN pin, but
  69          * we maintain the tradition of paranoia in this code.
  70          */
  71         if (file->f_flags & O_SYNC)
  72                 return 1;
  73         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
  74                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
  75                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
  76                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
  77           && addr >= __pa(high_memory);
  78 #elif defined(__x86_64__)
  79         /*
  80          * This is broken because it can generate memory type aliases,
  81          * which can cause cache corruptions
  82          * But it is only available for root and we have to be bug-to-bug
  83          * compatible with i386.
  84          */
  85         if (file->f_flags & O_SYNC)
  86                 return 1;
  87         /* same behaviour as i386. PAT always set to cached and MTRRs control the
  88            caching behaviour.
  89            Hopefully a full PAT implementation will fix that soon. */
  90         return 0;
  91 #elif defined(CONFIG_IA64)
  92         /*
  93          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
  94          */
  95         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
  96 #else
  97         /*
  98          * Accessing memory above the top the kernel knows about or through a file pointer
  99          * that was marked O_SYNC will be done non-cached.
 100          */
 101         if (file->f_flags & O_SYNC)
 102                 return 1;
 103         return addr >= __pa(high_memory);
 104 #endif
 105 }
 106
 107 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
 108 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
 109 {
 110         if (addr + count > __pa(high_memory))
 111                 return 0;
 112
 113         return 1;
 114 }
 115
 116 static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t size)
 117 {
 118         return 1;
 119 }
 120 #endif
 121
 122 #ifndef ARCH_HAS_DEV_MEM
 123 /*
 124  * This funcion reads the *physical* memory. The f_pos points directly to the
 125  * memory location.
 126  */
 127 static ssize_t read_mem(struct file * file, char __user * buf,
 128                         size_t count, loff_t *ppos)
 129 {
 130         unsigned long p = *ppos;
 131         ssize_t read, sz;
 132         char *ptr;
 133
 134         if (!valid_phys_addr_range(p, count))
 135                 return -EFAULT;
 136         read = 0;
 137 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 138         /* we don't have page 0 mapped on sparc and m68k.. */
 139         if (p < PAGE_SIZE) {
 140                 sz = PAGE_SIZE - p;
 141                 if (sz > count)
 142                         sz = count;
 143                 if (sz > 0) {
 144                         if (clear_user(buf, sz))
 145                                 return -EFAULT;
 146                         buf += sz;
 147                         p += sz;
 148                         count -= sz;
 149                         read += sz;
 150                 }
 151         }
 152 #endif
 153
 154         while (count > 0) {
 155                 /*
 156                  * Handle first page in case it's not aligned
 157                  */
 158                 if (-p & (PAGE_SIZE - 1))
 159                         sz = -p & (PAGE_SIZE - 1);
 160                 else
 161                         sz = PAGE_SIZE;
 162
 163                 sz = min_t(unsigned long, sz, count);
 164
 165                 /*
 166                  * On ia64 if a page has been mapped somewhere as
 167                  * uncached, then it must also be accessed uncached
 168                  * by the kernel or data corruption may occur
 169                  */
 170                 ptr = xlate_dev_mem_ptr(p);
 171
 172                 if (!range_is_allowed(p, p+count))
 173                         return -EPERM;
 174                 if (copy_to_user(buf, ptr, sz))
 175                         return -EFAULT;
 176                 buf += sz;
 177                 p += sz;
 178                 count -= sz;
 179                 read += sz;
 180         }
 181
 182         *ppos += read;
 183         return read;
 184 }
 185
 186 static ssize_t write_mem(struct file * file, const char __user * buf,
 187                          size_t count, loff_t *ppos)
 188 {
 189         unsigned long p = *ppos;
 190         ssize_t written, sz;
 191         unsigned long copied;
 192         void *ptr;
 193
 194         if (!valid_phys_addr_range(p, count))
 195                 return -EFAULT;
 196
 197         written = 0;
 198
 199 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 200         /* we don't have page 0 mapped on sparc and m68k.. */
 201         if (p < PAGE_SIZE) {
 202                 unsigned long sz = PAGE_SIZE - p;
 203                 if (sz > count)
 204                         sz = count;
 205                 /* Hmm. Do something? */
 206                 buf += sz;
 207                 p += sz;
 208                 count -= sz;
 209                 written += sz;
 210         }
 211 #endif
 212
 213         while (count > 0) {
 214                 /*
 215                  * Handle first page in case it's not aligned
 216                  */
 217                 if (-p & (PAGE_SIZE - 1))
 218                         sz = -p & (PAGE_SIZE - 1);
 219                 else
 220                         sz = PAGE_SIZE;
 221
 222                 sz = min_t(unsigned long, sz, count);
 223
 224                 /*
 225                  * On ia64 if a page has been mapped somewhere as
 226                  * uncached, then it must also be accessed uncached
 227                  * by the kernel or data corruption may occur
 228                  */
 229                 ptr = xlate_dev_mem_ptr(p);
 230
 231                 if (!range_is_allowed(ptr, ptr+sz))
 232                         return -EPERM;
 233                 copied = copy_from_user(ptr, buf, sz);
 234                 if (copied) {
 235                         written += sz - copied;
 236                         if (written)
 237                                 break;
 238                         return -EFAULT;
 239                 }
 240                 buf += sz;
 241                 p += sz;
 242                 count -= sz;
 243                 written += sz;
 244         }
 245
 246         *ppos += written;
 247         return written;
 248 }
 249 #endif
 250
 251 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 252 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 253                                      unsigned long size, pgprot_t vma_prot)
 254 {
 255 #ifdef pgprot_noncached
 256         unsigned long offset = pfn << PAGE_SHIFT;
 257
 258         if (uncached_access(file, offset))
 259                 return pgprot_noncached(vma_prot);
 260 #endif
 261         return vma_prot;
 262 }
 263 #endif
 264
 265 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 266 {
 267         size_t size = vma->vm_end - vma->vm_start;
 268
 269         if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, size))
 270                 return -EINVAL;
 271
 272         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 273                                                  size,
 274                                                  vma->vm_page_prot);
 275
 276         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 277         if (remap_pfn_range(vma,
 278                             vma->vm_start,
 279                             vma->vm_pgoff,
 280                             size,
 281                             vma->vm_page_prot))
 282                 return -EAGAIN;
 283         return 0;
 284 }
 285
 286 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
 287 {
 288         unsigned long pfn;
 289
 290         /* Turn a kernel-virtual address into a physical page frame */
 291         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 292
 293         /*
 294          * RED-PEN: on some architectures there is more mapped memory
 295          * than available in mem_map which pfn_valid checks
 296          * for. Perhaps should add a new macro here.
 297          *
 298          * RED-PEN: vmalloc is not supported right now.
 299          */
 300         if (!pfn_valid(pfn))
 301                 return -EIO;
 302
 303         vma->vm_pgoff = pfn;
 304         return mmap_mem(file, vma);
 305 }
 306
 307 #ifdef CONFIG_CRASH_DUMP
 308 /*
 309  * Read memory corresponding to the old kernel.
 310  */
 311 static ssize_t read_oldmem(struct file *file, char __user *buf,
 312                                 size_t count, loff_t *ppos)
 313 {
 314         unsigned long pfn, offset;
 315         size_t read = 0, csize;
 316         int rc = 0;
 317
 318         while (count) {
 319                 pfn = *ppos / PAGE_SIZE;
 320                 if (pfn > saved_max_pfn)
 321                         return read;
 322
 323                 offset = (unsigned long)(*ppos % PAGE_SIZE);
 324                 if (count > PAGE_SIZE - offset)
 325                         csize = PAGE_SIZE - offset;
 326                 else
 327                         csize = count;
 328
 329                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
 330                 if (rc < 0)
 331                         return rc;
 332                 buf += csize;
 333                 *ppos += csize;
 334                 read += csize;
 335                 count -= csize;
 336         }
 337         return read;
 338 }
 339 #endif
 340
 341 extern long vread(char *buf, char *addr, unsigned long count);
 342 extern long vwrite(char *buf, char *addr, unsigned long count);
 343
 344 /*
 345  * This function reads the *virtual* memory as seen by the kernel.
 346  */
 347 static ssize_t read_kmem(struct file *file, char __user *buf,
 348                          size_t count, loff_t *ppos)
 349 {
 350         unsigned long p = *ppos;
 351         ssize_t low_count, read, sz;
 352         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 353
 354         return -EPERM;
 355
 356         read = 0;
 357         if (p < (unsigned long) high_memory) {
 358                 low_count = count;
 359                 if (count > (unsigned long) high_memory - p)
 360                         low_count = (unsigned long) high_memory - p;
 361
 362 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 363                 /* we don't have page 0 mapped on sparc and m68k.. */
 364                 if (p < PAGE_SIZE && low_count > 0) {
 365                         size_t tmp = PAGE_SIZE - p;
 366                         if (tmp > low_count) tmp = low_count;
 367                         if (clear_user(buf, tmp))
 368                                 return -EFAULT;
 369                         buf += tmp;
 370                         p += tmp;
 371                         read += tmp;
 372                         low_count -= tmp;
 373                         count -= tmp;
 374                 }
 375 #endif
 376                 while (low_count > 0) {
 377                         /*
 378                          * Handle first page in case it's not aligned
 379                          */
 380                         if (-p & (PAGE_SIZE - 1))
 381                                 sz = -p & (PAGE_SIZE - 1);
 382                         else
 383                                 sz = PAGE_SIZE;
 384
 385                         sz = min_t(unsigned long, sz, low_count);
 386
 387                         /*
 388                          * On ia64 if a page has been mapped somewhere as
 389                          * uncached, then it must also be accessed uncached
 390                          * by the kernel or data corruption may occur
 391                          */
 392                         kbuf = xlate_dev_kmem_ptr((char *)p);
 393
 394                         if (copy_to_user(buf, kbuf, sz))
 395                                 return -EFAULT;
 396                         buf += sz;
 397                         p += sz;
 398                         read += sz;
 399                         low_count -= sz;
 400                         count -= sz;
 401                 }
 402         }
 403
 404         if (count > 0) {
 405                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 406                 if (!kbuf)
 407                         return -ENOMEM;
 408                 while (count > 0) {
 409                         int len = count;
 410
 411                         if (len > PAGE_SIZE)
 412                                 len = PAGE_SIZE;
 413                         len = vread(kbuf, (char *)p, len);
 414                         if (!len)
 415                                 break;
 416                         if (copy_to_user(buf, kbuf, len)) {
 417                                 free_page((unsigned long)kbuf);
 418                                 return -EFAULT;
 419                         }
 420                         count -= len;
 421                         buf += len;
 422                         read += len;
 423                         p += len;
 424                 }
 425                 free_page((unsigned long)kbuf);
 426         }
 427         *ppos = p;
 428         return read;
 429 }
 430
 431
 432 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 433 static ssize_t read_port(struct file * file, char __user * buf,
 434                          size_t count, loff_t *ppos)
 435 {
 436         unsigned long i = *ppos;
 437         char __user *tmp = buf;
 438
 439         if (!access_ok(VERIFY_WRITE, buf, count))
 440                 return -EFAULT;
 441         while (count-- > 0 && i < 65536) {
 442                 if (__put_user(inb(i),tmp) < 0)
 443                         return -EFAULT;
 444                 i++;
 445                 tmp++;
 446         }
 447         *ppos = i;
 448         return tmp-buf;
 449 }
 450
 451 static ssize_t write_port(struct file * file, const char __user * buf,
 452                           size_t count, loff_t *ppos)
 453 {
 454         unsigned long i = *ppos;
 455         const char __user * tmp = buf;
 456
 457         if (!access_ok(VERIFY_READ,buf,count))
 458                 return -EFAULT;
 459         while (count-- > 0 && i < 65536) {
 460                 char c;
 461                 if (__get_user(c, tmp)) {
 462                         if (tmp > buf)
 463                                 break;
 464                         return -EFAULT;
 465                 }
 466                 outb(c,i);
 467                 i++;
 468                 tmp++;
 469         }
 470         *ppos = i;
 471         return tmp-buf;
 472 }
 473 #endif
 474
 475 static ssize_t read_null(struct file * file, char __user * buf,
 476                          size_t count, loff_t *ppos)
 477 {
 478         return 0;
 479 }
 480
 481 static ssize_t write_null(struct file * file, const char __user * buf,
 482                           size_t count, loff_t *ppos)
 483 {
 484         return count;
 485 }
 486
 487 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 488                         struct splice_desc *sd)
 489 {
 490         return sd->len;
 491 }
 492
 493 static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
 494                                  loff_t *ppos, size_t len, unsigned int flags)
 495 {
 496         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 497 }
 498
 499 #ifdef CONFIG_MMU
 500 /*
 501  * For fun, we are using the MMU for this.
 502  */
 503 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
 504 {
 505         struct mm_struct *mm;
 506         struct vm_area_struct * vma;
 507         unsigned long addr=(unsigned long)buf;
 508
 509         mm = current->mm;
 510         /* Oops, this was forgotten before. -ben */
 511         down_read(&mm->mmap_sem);
 512
 513         /* For private mappings, just map in zero pages. */
 514         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
 515                 unsigned long count;
 516
 517                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
 518                         goto out_up;
 519                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
 520                         break;
 521                 count = vma->vm_end - addr;
 522                 if (count > size)
 523                         count = size;
 524
 525                 zap_page_range(vma, addr, count, NULL);
 526                 zeromap_page_range(vma, addr, count, PAGE_COPY);
 527
 528                 size -= count;
 529                 buf += count;
 530                 addr += count;
 531                 if (size == 0)
 532                         goto out_up;
 533         }
 534
 535         up_read(&mm->mmap_sem);
 536
 537         /* The shared case is hard. Let's do the conventional zeroing. */
 538         do {
 539                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
 540                 if (unwritten)
 541                         return size + unwritten - PAGE_SIZE;
 542                 cond_resched();
 543                 buf += PAGE_SIZE;
 544                 size -= PAGE_SIZE;
 545         } while (size);
 546
 547         return size;
 548 out_up:
 549         up_read(&mm->mmap_sem);
 550         return size;
 551 }
 552
 553 static ssize_t read_zero(struct file * file, char __user * buf,
 554                          size_t count, loff_t *ppos)
 555 {
 556         unsigned long left, unwritten, written = 0;
 557
 558         if (!count)
 559                 return 0;
 560
 561         if (!access_ok(VERIFY_WRITE, buf, count))
 562                 return -EFAULT;
 563
 564         left = count;
 565
 566         /* do we want to be clever? Arbitrary cut-off */
 567         if (count >= PAGE_SIZE*4) {
 568                 unsigned long partial;
 569
 570                 /* How much left of the page? */
 571                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
 572                 unwritten = clear_user(buf, partial);
 573                 written = partial - unwritten;
 574                 if (unwritten)
 575                         goto out;
 576                 left -= partial;
 577                 buf += partial;
 578                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
 579                 written += (left & PAGE_MASK) - unwritten;
 580                 if (unwritten)
 581                         goto out;
 582                 buf += left & PAGE_MASK;
 583                 left &= ~PAGE_MASK;
 584         }
 585         unwritten = clear_user(buf, left);
 586         written += left - unwritten;
 587 out:
 588         return written ? written : -EFAULT;
 589 }
 590
 591 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 592 {
 593         if (vma->vm_flags & VM_SHARED)
 594                 return shmem_zero_setup(vma);
 595         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
 596                 return -EAGAIN;
 597         return 0;
 598 }
 599 #else /* CONFIG_MMU */
 600 static ssize_t read_zero(struct file * file, char * buf,
 601                          size_t count, loff_t *ppos)
 602 {
 603         size_t todo = count;
 604
 605         while (todo) {
 606                 size_t chunk = todo;
 607
 608                 if (chunk > 4096)
 609                         chunk = 4096;   /* Just for latency reasons */
 610                 if (clear_user(buf, chunk))
 611                         return -EFAULT;
 612                 buf += chunk;
 613                 todo -= chunk;
 614                 cond_resched();
 615         }
 616         return count;
 617 }
 618
 619 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 620 {
 621         return -ENOSYS;
 622 }
 623 #endif /* CONFIG_MMU */
 624
 625 static ssize_t write_full(struct file * file, const char __user * buf,
 626                           size_t count, loff_t *ppos)
 627 {
 628         return -ENOSPC;
 629 }
 630
 631 /*
 632  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 633  * can fopen() both devices with "a" now.  This was previously impossible.
 634  * -- SRB.
 635  */
 636
 637 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
 638 {
 639         return file->f_pos = 0;
 640 }
 641
 642 /*
 643  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 644  * check against negative addresses: they are ok. The return value is weird,
 645  * though, in that case (0).
 646  *
 647  * also note that seeking relative to the "end of file" isn't supported:
 648  * it has no meaning, so it returns -EINVAL.
 649  */
 650 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
 651 {
 652         loff_t ret;
 653
 654         mutex_lock(&file->f_dentry->d_inode->i_mutex);
 655         switch (orig) {
 656                 case 0:
 657                         file->f_pos = offset;
 658                         ret = file->f_pos;
 659                         force_successful_syscall_return();
 660                         break;
 661                 case 1:
 662                         file->f_pos += offset;
 663                         ret = file->f_pos;
 664                         force_successful_syscall_return();
 665                         break;
 666                 default:
 667                         ret = -EINVAL;
 668         }
 669         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 670         return ret;
 671 }
 672
 673 static int open_port(struct inode * inode, struct file * filp)
 674 {
 675         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 676 }
 677
 678 #define zero_lseek      null_lseek
 679 #define full_lseek      null_lseek
 680 #define write_zero      write_null
 681 #define read_full       read_zero
 682 #define open_mem        open_port
 683 #define open_kmem       open_mem
 684 #define open_oldmem     open_mem
 685
 686 #ifndef ARCH_HAS_DEV_MEM
 687 static struct file_operations mem_fops = {
 688         .llseek         = memory_lseek,
 689         .read           = read_mem,
 690         .write          = write_mem,
 691         .mmap           = mmap_mem,
 692         .open           = open_mem,
 693 };
 694 #else
 695 extern struct file_operations mem_fops;
 696 #endif
 697
 698 static struct file_operations kmem_fops = {
 699         .llseek         = memory_lseek,
 700         .read           = read_kmem,
 701         .mmap           = mmap_kmem,
 702         .open           = open_kmem,
 703 };
 704
 705 static struct file_operations null_fops = {
 706         .llseek         = null_lseek,
 707         .read           = read_null,
 708         .write          = write_null,
 709         .splice_write   = splice_write_null,
 710 };
 711
 712 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 713 static struct file_operations port_fops = {
 714         .llseek         = memory_lseek,
 715         .read           = read_port,
 716         .write          = write_port,
 717         .open           = open_port,
 718 };
 719 #endif
 720
 721 static struct file_operations zero_fops = {
 722         .llseek         = zero_lseek,
 723         .read           = read_zero,
 724         .write          = write_zero,
 725         .mmap           = mmap_zero,
 726 };
 727
 728 static struct backing_dev_info zero_bdi = {
 729         .capabilities   = BDI_CAP_MAP_COPY,
 730 };
 731
 732 static struct file_operations full_fops = {
 733         .llseek         = full_lseek,
 734         .read           = read_full,
 735         .write          = write_full,
 736 };
 737
 738 #ifdef CONFIG_CRASH_DUMP
 739 static struct file_operations oldmem_fops = {
 740         .read   = read_oldmem,
 741         .open   = open_oldmem,
 742 };
 743 #endif
 744
 745 static ssize_t kmsg_write(struct file * file, const char __user * buf,
 746                           size_t count, loff_t *ppos)
 747 {
 748         char *tmp;
 749         ssize_t ret;
 750
 751         tmp = kmalloc(count + 1, GFP_KERNEL);
 752         if (tmp == NULL)
 753                 return -ENOMEM;
 754         ret = -EFAULT;
 755         if (!copy_from_user(tmp, buf, count)) {
 756                 tmp[count] = 0;
 757                 ret = printk("%s", tmp);
 758                 if (ret > count)
 759                         /* printk can add a prefix */
 760                         ret = count;
 761         }
 762         kfree(tmp);
 763         return ret;
 764 }
 765
 766 static struct file_operations kmsg_fops = {
 767         .write =        kmsg_write,
 768 };
 769
 770 static int memory_open(struct inode * inode, struct file * filp)
 771 {
 772         switch (iminor(inode)) {
 773                 case 1:
 774                         filp->f_op = &mem_fops;
 775                         break;
 776                 case 2:
 777                         filp->f_op = &kmem_fops;
 778                         break;
 779                 case 3:
 780                         filp->f_op = &null_fops;
 781                         break;
 782 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 783                 case 4:
 784                         filp->f_op = &port_fops;
 785                         break;
 786 #endif
 787                 case 5:
 788                         filp->f_mapping->backing_dev_info = &zero_bdi;
 789                         filp->f_op = &zero_fops;
 790                         break;
 791                 case 7:
 792                         filp->f_op = &full_fops;
 793                         break;
 794                 case 8:
 795                         filp->f_op = &random_fops;
 796                         break;
 797                 case 9:
 798                         filp->f_op = &urandom_fops;
 799                         break;
 800                 case 11:
 801                         filp->f_op = &kmsg_fops;
 802                         break;
 803 #ifdef CONFIG_CRASH_DUMP
 804                 case 12:
 805                         filp->f_op = &oldmem_fops;
 806                         break;
 807 #endif
 808                 default:
 809                         return -ENXIO;
 810         }
 811         if (filp->f_op && filp->f_op->open)
 812                 return filp->f_op->open(inode,filp);
 813         return 0;
 814 }
 815
 816 static struct file_operations memory_fops = {
 817         .open           = memory_open,  /* just a selector for the real open */
 818 };
 819
 820 static const struct {
 821         unsigned int            minor;
 822         char                    *name;
 823         umode_t                 mode;
 824         const struct file_operations    *fops;
 825 } devlist[] = { /* list of minor devices */
 826         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
 827         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
 828 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 829         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
 830 #endif
 831         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
 832         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
 833         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
 834         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
 835         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
 836 #ifdef CONFIG_CRASH_DUMP
 837         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
 838 #endif
 839 };
 840
 841 static struct class *mem_class;
 842
 843 static int __init chr_dev_init(void)
 844 {
 845         int i;
 846
 847         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 848                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 849
 850         mem_class = class_create(THIS_MODULE, "mem");
 851         for (i = 0; i < ARRAY_SIZE(devlist); i++) {
 852                 class_device_create(mem_class, NULL,
 853                                         MKDEV(MEM_MAJOR, devlist[i].minor),
 854                                         NULL, devlist[i].name);
 855                 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
 856                                 S_IFCHR | devlist[i].mode, devlist[i].name);
 857         }
 858
 859         return 0;
 860 }
 861
 862 fs_initcall(chr_dev_init);