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/backing-dev.h>
  27
  28 #include <asm/uaccess.h>
  29 #include <asm/io.h>
  30
  31 #ifdef CONFIG_IA64
  32 # include <linux/efi.h>
  33 #endif
  34
  35 #if defined(CONFIG_S390_TAPE) && defined(CONFIG_S390_TAPE_CHAR)
  36 extern void tapechar_init(void);
  37 #endif
  38
  39 /*
  40  * Architectures vary in how they handle caching for addresses
  41  * outside of main memory.
  42  *
  43  */
  44 static inline int uncached_access(struct file *file, unsigned long addr)
  45 {
  46 #if defined(__i386__)
  47         /*
  48          * On the PPro and successors, the MTRRs are used to set
  49          * memory types for physical addresses outside main memory,
  50          * so blindly setting PCD or PWT on those pages is wrong.
  51          * For Pentiums and earlier, the surround logic should disable
  52          * caching for the high addresses through the KEN pin, but
  53          * we maintain the tradition of paranoia in this code.
  54          */
  55         if (file->f_flags & O_SYNC)
  56                 return 1;
  57         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
  58                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
  59                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
  60                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
  61           && addr >= __pa(high_memory);
  62 #elif defined(__x86_64__)
  63         /*
  64          * This is broken because it can generate memory type aliases,
  65          * which can cause cache corruptions
  66          * But it is only available for root and we have to be bug-to-bug
  67          * compatible with i386.
  68          */
  69         if (file->f_flags & O_SYNC)
  70                 return 1;
  71         /* same behaviour as i386. PAT always set to cached and MTRRs control the
  72            caching behaviour.
  73            Hopefully a full PAT implementation will fix that soon. */
  74         return 0;
  75 #elif defined(CONFIG_IA64)
  76         /*
  77          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
  78          */
  79         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
  80 #else
  81         /*
  82          * Accessing memory above the top the kernel knows about or through a file pointer
  83          * that was marked O_SYNC will be done non-cached.
  84          */
  85         if (file->f_flags & O_SYNC)
  86                 return 1;
  87         return addr >= __pa(high_memory);
  88 #endif
  89 }
  90
  91 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  92 static inline int valid_phys_addr_range(unsigned long addr, size_t *count)
  93 {
  94         unsigned long end_mem;
  95
  96         end_mem = __pa(high_memory);
  97         if (addr >= end_mem)
  98                 return 0;
  99
 100         if (*count > end_mem - addr)
 101                 *count = end_mem - addr;
 102
 103         return 1;
 104 }
 105 #endif
 106
 107 /*
 108  * This funcion reads the *physical* memory. The f_pos points directly to the
 109  * memory location.
 110  */
 111 static ssize_t read_mem(struct file * file, char __user * buf,
 112                         size_t count, loff_t *ppos)
 113 {
 114         unsigned long p = *ppos;
 115         ssize_t read, sz;
 116         char *ptr;
 117
 118         if (!valid_phys_addr_range(p, &count))
 119                 return -EFAULT;
 120         read = 0;
 121 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 122         /* we don't have page 0 mapped on sparc and m68k.. */
 123         if (p < PAGE_SIZE) {
 124                 sz = PAGE_SIZE - p;
 125                 if (sz > count)
 126                         sz = count;
 127                 if (sz > 0) {
 128                         if (clear_user(buf, sz))
 129                                 return -EFAULT;
 130                         buf += sz;
 131                         p += sz;
 132                         count -= sz;
 133                         read += sz;
 134                 }
 135         }
 136 #endif
 137
 138         while (count > 0) {
 139                 /*
 140                  * Handle first page in case it's not aligned
 141                  */
 142                 if (-p & (PAGE_SIZE - 1))
 143                         sz = -p & (PAGE_SIZE - 1);
 144                 else
 145                         sz = PAGE_SIZE;
 146
 147                 sz = min_t(unsigned long, sz, count);
 148
 149                 /*
 150                  * On ia64 if a page has been mapped somewhere as
 151                  * uncached, then it must also be accessed uncached
 152                  * by the kernel or data corruption may occur
 153                  */
 154                 ptr = xlate_dev_mem_ptr(p);
 155
 156                 if (copy_to_user(buf, ptr, sz))
 157                         return -EFAULT;
 158                 buf += sz;
 159                 p += sz;
 160                 count -= sz;
 161                 read += sz;
 162         }
 163
 164         *ppos += read;
 165         return read;
 166 }
 167
 168 static ssize_t write_mem(struct file * file, const char __user * buf,
 169                          size_t count, loff_t *ppos)
 170 {
 171         unsigned long p = *ppos;
 172         ssize_t written, sz;
 173         unsigned long copied;
 174         void *ptr;
 175
 176         if (!valid_phys_addr_range(p, &count))
 177                 return -EFAULT;
 178
 179         written = 0;
 180
 181 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 182         /* we don't have page 0 mapped on sparc and m68k.. */
 183         if (p < PAGE_SIZE) {
 184                 unsigned long sz = PAGE_SIZE - p;
 185                 if (sz > count)
 186                         sz = count;
 187                 /* Hmm. Do something? */
 188                 buf += sz;
 189                 p += sz;
 190                 count -= sz;
 191                 written += sz;
 192         }
 193 #endif
 194
 195         while (count > 0) {
 196                 /*
 197                  * Handle first page in case it's not aligned
 198                  */
 199                 if (-p & (PAGE_SIZE - 1))
 200                         sz = -p & (PAGE_SIZE - 1);
 201                 else
 202                         sz = PAGE_SIZE;
 203
 204                 sz = min_t(unsigned long, sz, count);
 205
 206                 /*
 207                  * On ia64 if a page has been mapped somewhere as
 208                  * uncached, then it must also be accessed uncached
 209                  * by the kernel or data corruption may occur
 210                  */
 211                 ptr = xlate_dev_mem_ptr(p);
 212
 213                 copied = copy_from_user(ptr, buf, sz);
 214                 if (copied) {
 215                         ssize_t ret;
 216
 217                         ret = written + (sz - copied);
 218                         if (ret)
 219                                 return ret;
 220                         return -EFAULT;
 221                 }
 222                 buf += sz;
 223                 p += sz;
 224                 count -= sz;
 225                 written += sz;
 226         }
 227
 228         *ppos += written;
 229         return written;
 230 }
 231
 232 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 233 {
 234 #if defined(__HAVE_PHYS_MEM_ACCESS_PROT)
 235         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 236
 237         vma->vm_page_prot = phys_mem_access_prot(file, offset,
 238                                                  vma->vm_end - vma->vm_start,
 239                                                  vma->vm_page_prot);
 240 #elif defined(pgprot_noncached)
 241         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 242         int uncached;
 243
 244         uncached = uncached_access(file, offset);
 245         if (uncached)
 246                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 247 #endif
 248
 249         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 250         if (remap_pfn_range(vma,
 251                             vma->vm_start,
 252                             vma->vm_pgoff,
 253                             vma->vm_end-vma->vm_start,
 254                             vma->vm_page_prot))
 255                 return -EAGAIN;
 256         return 0;
 257 }
 258
 259 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
 260 {
 261         unsigned long long val;
 262         /*
 263          * RED-PEN: on some architectures there is more mapped memory
 264          * than available in mem_map which pfn_valid checks
 265          * for. Perhaps should add a new macro here.
 266          *
 267          * RED-PEN: vmalloc is not supported right now.
 268          */
 269         if (!pfn_valid(vma->vm_pgoff))
 270                 return -EIO;
 271         val = (u64)vma->vm_pgoff << PAGE_SHIFT;
 272         vma->vm_pgoff = __pa(val) >> PAGE_SHIFT;
 273         return mmap_mem(file, vma);
 274 }
 275
 276 extern long vread(char *buf, char *addr, unsigned long count);
 277 extern long vwrite(char *buf, char *addr, unsigned long count);
 278
 279 /*
 280  * This function reads the *virtual* memory as seen by the kernel.
 281  */
 282 static ssize_t read_kmem(struct file *file, char __user *buf,
 283                          size_t count, loff_t *ppos)
 284 {
 285         unsigned long p = *ppos;
 286         ssize_t low_count, read, sz;
 287         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 288
 289         read = 0;
 290         if (p < (unsigned long) high_memory) {
 291                 low_count = count;
 292                 if (count > (unsigned long) high_memory - p)
 293                         low_count = (unsigned long) high_memory - p;
 294
 295 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 296                 /* we don't have page 0 mapped on sparc and m68k.. */
 297                 if (p < PAGE_SIZE && low_count > 0) {
 298                         size_t tmp = PAGE_SIZE - p;
 299                         if (tmp > low_count) tmp = low_count;
 300                         if (clear_user(buf, tmp))
 301                                 return -EFAULT;
 302                         buf += tmp;
 303                         p += tmp;
 304                         read += tmp;
 305                         low_count -= tmp;
 306                         count -= tmp;
 307                 }
 308 #endif
 309                 while (low_count > 0) {
 310                         /*
 311                          * Handle first page in case it's not aligned
 312                          */
 313                         if (-p & (PAGE_SIZE - 1))
 314                                 sz = -p & (PAGE_SIZE - 1);
 315                         else
 316                                 sz = PAGE_SIZE;
 317
 318                         sz = min_t(unsigned long, sz, low_count);
 319
 320                         /*
 321                          * On ia64 if a page has been mapped somewhere as
 322                          * uncached, then it must also be accessed uncached
 323                          * by the kernel or data corruption may occur
 324                          */
 325                         kbuf = xlate_dev_kmem_ptr((char *)p);
 326
 327                         if (copy_to_user(buf, kbuf, sz))
 328                                 return -EFAULT;
 329                         buf += sz;
 330                         p += sz;
 331                         read += sz;
 332                         low_count -= sz;
 333                         count -= sz;
 334                 }
 335         }
 336
 337         if (count > 0) {
 338                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 339                 if (!kbuf)
 340                         return -ENOMEM;
 341                 while (count > 0) {
 342                         int len = count;
 343
 344                         if (len > PAGE_SIZE)
 345                                 len = PAGE_SIZE;
 346                         len = vread(kbuf, (char *)p, len);
 347                         if (!len)
 348                                 break;
 349                         if (copy_to_user(buf, kbuf, len)) {
 350                                 free_page((unsigned long)kbuf);
 351                                 return -EFAULT;
 352                         }
 353                         count -= len;
 354                         buf += len;
 355                         read += len;
 356                         p += len;
 357                 }
 358                 free_page((unsigned long)kbuf);
 359         }
 360         *ppos = p;
 361         return read;
 362 }
 363
 364
 365 static inline ssize_t
 366 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
 367               size_t count, loff_t *ppos)
 368 {
 369         ssize_t written, sz;
 370         unsigned long copied;
 371
 372         written = 0;
 373 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 374         /* we don't have page 0 mapped on sparc and m68k.. */
 375         if (realp < PAGE_SIZE) {
 376                 unsigned long sz = PAGE_SIZE - realp;
 377                 if (sz > count)
 378                         sz = count;
 379                 /* Hmm. Do something? */
 380                 buf += sz;
 381                 p += sz;
 382                 realp += sz;
 383                 count -= sz;
 384                 written += sz;
 385         }
 386 #endif
 387
 388         while (count > 0) {
 389                 char *ptr;
 390                 /*
 391                  * Handle first page in case it's not aligned
 392                  */
 393                 if (-realp & (PAGE_SIZE - 1))
 394                         sz = -realp & (PAGE_SIZE - 1);
 395                 else
 396                         sz = PAGE_SIZE;
 397
 398                 sz = min_t(unsigned long, sz, count);
 399
 400                 /*
 401                  * On ia64 if a page has been mapped somewhere as
 402                  * uncached, then it must also be accessed uncached
 403                  * by the kernel or data corruption may occur
 404                  */
 405                 ptr = xlate_dev_kmem_ptr(p);
 406
 407                 copied = copy_from_user(ptr, buf, sz);
 408                 if (copied) {
 409                         ssize_t ret;
 410
 411                         ret = written + (sz - copied);
 412                         if (ret)
 413                                 return ret;
 414                         return -EFAULT;
 415                 }
 416                 buf += sz;
 417                 p += sz;
 418                 realp += sz;
 419                 count -= sz;
 420                 written += sz;
 421         }
 422
 423         *ppos += written;
 424         return written;
 425 }
 426
 427
 428 /*
 429  * This function writes to the *virtual* memory as seen by the kernel.
 430  */
 431 static ssize_t write_kmem(struct file * file, const char __user * buf,
 432                           size_t count, loff_t *ppos)
 433 {
 434         unsigned long p = *ppos;
 435         ssize_t wrote = 0;
 436         ssize_t virtr = 0;
 437         ssize_t written;
 438         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 439
 440         if (p < (unsigned long) high_memory) {
 441
 442                 wrote = count;
 443                 if (count > (unsigned long) high_memory - p)
 444                         wrote = (unsigned long) high_memory - p;
 445
 446                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
 447                 if (written != wrote)
 448                         return written;
 449                 wrote = written;
 450                 p += wrote;
 451                 buf += wrote;
 452                 count -= wrote;
 453         }
 454
 455         if (count > 0) {
 456                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 457                 if (!kbuf)
 458                         return wrote ? wrote : -ENOMEM;
 459                 while (count > 0) {
 460                         int len = count;
 461
 462                         if (len > PAGE_SIZE)
 463                                 len = PAGE_SIZE;
 464                         if (len) {
 465                                 written = copy_from_user(kbuf, buf, len);
 466                                 if (written) {
 467                                         ssize_t ret;
 468
 469                                         free_page((unsigned long)kbuf);
 470                                         ret = wrote + virtr + (len - written);
 471                                         return ret ? ret : -EFAULT;
 472                                 }
 473                         }
 474                         len = vwrite(kbuf, (char *)p, len);
 475                         count -= len;
 476                         buf += len;
 477                         virtr += len;
 478                         p += len;
 479                 }
 480                 free_page((unsigned long)kbuf);
 481         }
 482
 483         *ppos = p;
 484         return virtr + wrote;
 485 }
 486
 487 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 488 static ssize_t read_port(struct file * file, char __user * buf,
 489                          size_t count, loff_t *ppos)
 490 {
 491         unsigned long i = *ppos;
 492         char __user *tmp = buf;
 493
 494         if (!access_ok(VERIFY_WRITE, buf, count))
 495                 return -EFAULT;
 496         while (count-- > 0 && i < 65536) {
 497                 if (__put_user(inb(i),tmp) < 0)
 498                         return -EFAULT;
 499                 i++;
 500                 tmp++;
 501         }
 502         *ppos = i;
 503         return tmp-buf;
 504 }
 505
 506 static ssize_t write_port(struct file * file, const char __user * buf,
 507                           size_t count, loff_t *ppos)
 508 {
 509         unsigned long i = *ppos;
 510         const char __user * tmp = buf;
 511
 512         if (!access_ok(VERIFY_READ,buf,count))
 513                 return -EFAULT;
 514         while (count-- > 0 && i < 65536) {
 515                 char c;
 516                 if (__get_user(c, tmp))
 517                         return -EFAULT;
 518                 outb(c,i);
 519                 i++;
 520                 tmp++;
 521         }
 522         *ppos = i;
 523         return tmp-buf;
 524 }
 525 #endif
 526
 527 static ssize_t read_null(struct file * file, char __user * buf,
 528                          size_t count, loff_t *ppos)
 529 {
 530         return 0;
 531 }
 532
 533 static ssize_t write_null(struct file * file, const char __user * buf,
 534                           size_t count, loff_t *ppos)
 535 {
 536         return count;
 537 }
 538
 539 #ifdef CONFIG_MMU
 540 /*
 541  * For fun, we are using the MMU for this.
 542  */
 543 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
 544 {
 545         struct mm_struct *mm;
 546         struct vm_area_struct * vma;
 547         unsigned long addr=(unsigned long)buf;
 548
 549         mm = current->mm;
 550         /* Oops, this was forgotten before. -ben */
 551         down_read(&mm->mmap_sem);
 552
 553         /* For private mappings, just map in zero pages. */
 554         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
 555                 unsigned long count;
 556
 557                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
 558                         goto out_up;
 559                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
 560                         break;
 561                 count = vma->vm_end - addr;
 562                 if (count > size)
 563                         count = size;
 564
 565                 zap_page_range(vma, addr, count, NULL);
 566                 zeromap_page_range(vma, addr, count, PAGE_COPY);
 567
 568                 size -= count;
 569                 buf += count;
 570                 addr += count;
 571                 if (size == 0)
 572                         goto out_up;
 573         }
 574
 575         up_read(&mm->mmap_sem);
 576
 577         /* The shared case is hard. Let's do the conventional zeroing. */
 578         do {
 579                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
 580                 if (unwritten)
 581                         return size + unwritten - PAGE_SIZE;
 582                 cond_resched();
 583                 buf += PAGE_SIZE;
 584                 size -= PAGE_SIZE;
 585         } while (size);
 586
 587         return size;
 588 out_up:
 589         up_read(&mm->mmap_sem);
 590         return size;
 591 }
 592
 593 static ssize_t read_zero(struct file * file, char __user * buf,
 594                          size_t count, loff_t *ppos)
 595 {
 596         unsigned long left, unwritten, written = 0;
 597
 598         if (!count)
 599                 return 0;
 600
 601         if (!access_ok(VERIFY_WRITE, buf, count))
 602                 return -EFAULT;
 603
 604         left = count;
 605
 606         /* do we want to be clever? Arbitrary cut-off */
 607         if (count >= PAGE_SIZE*4) {
 608                 unsigned long partial;
 609
 610                 /* How much left of the page? */
 611                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
 612                 unwritten = clear_user(buf, partial);
 613                 written = partial - unwritten;
 614                 if (unwritten)
 615                         goto out;
 616                 left -= partial;
 617                 buf += partial;
 618                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
 619                 written += (left & PAGE_MASK) - unwritten;
 620                 if (unwritten)
 621                         goto out;
 622                 buf += left & PAGE_MASK;
 623                 left &= ~PAGE_MASK;
 624         }
 625         unwritten = clear_user(buf, left);
 626         written += left - unwritten;
 627 out:
 628         return written ? written : -EFAULT;
 629 }
 630
 631 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 632 {
 633         if (vma->vm_flags & VM_SHARED)
 634                 return shmem_zero_setup(vma);
 635         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
 636                 return -EAGAIN;
 637         return 0;
 638 }
 639 #else /* CONFIG_MMU */
 640 static ssize_t read_zero(struct file * file, char * buf,
 641                          size_t count, loff_t *ppos)
 642 {
 643         size_t todo = count;
 644
 645         while (todo) {
 646                 size_t chunk = todo;
 647
 648                 if (chunk > 4096)
 649                         chunk = 4096;   /* Just for latency reasons */
 650                 if (clear_user(buf, chunk))
 651                         return -EFAULT;
 652                 buf += chunk;
 653                 todo -= chunk;
 654                 cond_resched();
 655         }
 656         return count;
 657 }
 658
 659 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 660 {
 661         return -ENOSYS;
 662 }
 663 #endif /* CONFIG_MMU */
 664
 665 static ssize_t write_full(struct file * file, const char __user * buf,
 666                           size_t count, loff_t *ppos)
 667 {
 668         return -ENOSPC;
 669 }
 670
 671 /*
 672  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 673  * can fopen() both devices with "a" now.  This was previously impossible.
 674  * -- SRB.
 675  */
 676
 677 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
 678 {
 679         return file->f_pos = 0;
 680 }
 681
 682 /*
 683  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 684  * check against negative addresses: they are ok. The return value is weird,
 685  * though, in that case (0).
 686  *
 687  * also note that seeking relative to the "end of file" isn't supported:
 688  * it has no meaning, so it returns -EINVAL.
 689  */
 690 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
 691 {
 692         loff_t ret;
 693
 694         down(&file->f_dentry->d_inode->i_sem);
 695         switch (orig) {
 696                 case 0:
 697                         file->f_pos = offset;
 698                         ret = file->f_pos;
 699                         force_successful_syscall_return();
 700                         break;
 701                 case 1:
 702                         file->f_pos += offset;
 703                         ret = file->f_pos;
 704                         force_successful_syscall_return();
 705                         break;
 706                 default:
 707                         ret = -EINVAL;
 708         }
 709         up(&file->f_dentry->d_inode->i_sem);
 710         return ret;
 711 }
 712
 713 static int open_port(struct inode * inode, struct file * filp)
 714 {
 715         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 716 }
 717
 718 #define zero_lseek      null_lseek
 719 #define full_lseek      null_lseek
 720 #define write_zero      write_null
 721 #define read_full       read_zero
 722 #define open_mem        open_port
 723 #define open_kmem       open_mem
 724
 725 static struct file_operations mem_fops = {
 726         .llseek         = memory_lseek,
 727         .read           = read_mem,
 728         .write          = write_mem,
 729         .mmap           = mmap_mem,
 730         .open           = open_mem,
 731 };
 732
 733 static struct file_operations kmem_fops = {
 734         .llseek         = memory_lseek,
 735         .read           = read_kmem,
 736         .write          = write_kmem,
 737         .mmap           = mmap_kmem,
 738         .open           = open_kmem,
 739 };
 740
 741 static struct file_operations null_fops = {
 742         .llseek         = null_lseek,
 743         .read           = read_null,
 744         .write          = write_null,
 745 };
 746
 747 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 748 static struct file_operations port_fops = {
 749         .llseek         = memory_lseek,
 750         .read           = read_port,
 751         .write          = write_port,
 752         .open           = open_port,
 753 };
 754 #endif
 755
 756 static struct file_operations zero_fops = {
 757         .llseek         = zero_lseek,
 758         .read           = read_zero,
 759         .write          = write_zero,
 760         .mmap           = mmap_zero,
 761 };
 762
 763 static struct backing_dev_info zero_bdi = {
 764         .capabilities   = BDI_CAP_MAP_COPY,
 765 };
 766
 767 static struct file_operations full_fops = {
 768         .llseek         = full_lseek,
 769         .read           = read_full,
 770         .write          = write_full,
 771 };
 772
 773 static ssize_t kmsg_write(struct file * file, const char __user * buf,
 774                           size_t count, loff_t *ppos)
 775 {
 776         char *tmp;
 777         int ret;
 778
 779         tmp = kmalloc(count + 1, GFP_KERNEL);
 780         if (tmp == NULL)
 781                 return -ENOMEM;
 782         ret = -EFAULT;
 783         if (!copy_from_user(tmp, buf, count)) {
 784                 tmp[count] = 0;
 785                 ret = printk("%s", tmp);
 786         }
 787         kfree(tmp);
 788         return ret;
 789 }
 790
 791 static struct file_operations kmsg_fops = {
 792         .write =        kmsg_write,
 793 };
 794
 795 static int memory_open(struct inode * inode, struct file * filp)
 796 {
 797         switch (iminor(inode)) {
 798                 case 1:
 799                         filp->f_op = &mem_fops;
 800                         break;
 801                 case 2:
 802                         filp->f_op = &kmem_fops;
 803                         break;
 804                 case 3:
 805                         filp->f_op = &null_fops;
 806                         break;
 807 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 808                 case 4:
 809                         filp->f_op = &port_fops;
 810                         break;
 811 #endif
 812                 case 5:
 813                         filp->f_mapping->backing_dev_info = &zero_bdi;
 814                         filp->f_op = &zero_fops;
 815                         break;
 816                 case 7:
 817                         filp->f_op = &full_fops;
 818                         break;
 819                 case 8:
 820                         filp->f_op = &random_fops;
 821                         break;
 822                 case 9:
 823                         filp->f_op = &urandom_fops;
 824                         break;
 825                 case 11:
 826                         filp->f_op = &kmsg_fops;
 827                         break;
 828                 default:
 829                         return -ENXIO;
 830         }
 831         if (filp->f_op && filp->f_op->open)
 832                 return filp->f_op->open(inode,filp);
 833         return 0;
 834 }
 835
 836 static struct file_operations memory_fops = {
 837         .open           = memory_open,  /* just a selector for the real open */
 838 };
 839
 840 static const struct {
 841         unsigned int            minor;
 842         char                    *name;
 843         umode_t                 mode;
 844         struct file_operations  *fops;
 845 } devlist[] = { /* list of minor devices */
 846         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
 847         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
 848         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
 849 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 850         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
 851 #endif
 852         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
 853         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
 854         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
 855         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
 856         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
 857 };
 858
 859 static struct class_simple *mem_class;
 860
 861 static int __init chr_dev_init(void)
 862 {
 863         int i;
 864
 865         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 866                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 867
 868         mem_class = class_simple_create(THIS_MODULE, "mem");
 869         for (i = 0; i < ARRAY_SIZE(devlist); i++) {
 870                 class_simple_device_add(mem_class,
 871                                         MKDEV(MEM_MAJOR, devlist[i].minor),
 872                                         NULL, devlist[i].name);
 873                 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
 874                                 S_IFCHR | devlist[i].mode, devlist[i].name);
 875         }
 876
 877         return 0;
 878 }
 879
 880 fs_initcall(chr_dev_init);