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   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
  31 #include <asm/uaccess.h>
  32 #include <asm/io.h>
  33
  34 #ifdef CONFIG_IA64
  35 # include <linux/efi.h>
  36 #endif
  37
  38 /*
  39  * Architectures vary in how they handle caching for addresses
  40  * outside of main memory.
  41  *
  42  */
  43 static inline int uncached_access(struct file *file, unsigned long addr)
  44 {
  45 #if defined(__i386__)
  46         /*
  47          * On the PPro and successors, the MTRRs are used to set
  48          * memory types for physical addresses outside main memory,
  49          * so blindly setting PCD or PWT on those pages is wrong.
  50          * For Pentiums and earlier, the surround logic should disable
  51          * caching for the high addresses through the KEN pin, but
  52          * we maintain the tradition of paranoia in this code.
  53          */
  54         if (file->f_flags & O_SYNC)
  55                 return 1;
  56         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
  57                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
  58                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
  59                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
  60           && addr >= __pa(high_memory);
  61 #elif defined(__x86_64__)
  62         /*
  63          * This is broken because it can generate memory type aliases,
  64          * which can cause cache corruptions
  65          * But it is only available for root and we have to be bug-to-bug
  66          * compatible with i386.
  67          */
  68         if (file->f_flags & O_SYNC)
  69                 return 1;
  70         /* same behaviour as i386. PAT always set to cached and MTRRs control the
  71            caching behaviour.
  72            Hopefully a full PAT implementation will fix that soon. */
  73         return 0;
  74 #elif defined(CONFIG_IA64)
  75         /*
  76          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
  77          */
  78         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
  79 #else
  80         /*
  81          * Accessing memory above the top the kernel knows about or through a file pointer
  82          * that was marked O_SYNC will be done non-cached.
  83          */
  84         if (file->f_flags & O_SYNC)
  85                 return 1;
  86         return addr >= __pa(high_memory);
  87 #endif
  88 }
  89
  90 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  91 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
  92 {
  93         if (addr + count > __pa(high_memory))
  94                 return 0;
  95
  96         return 1;
  97 }
  98
  99 static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t size)
 100 {
 101         return 1;
 102 }
 103 #endif
 104
 105 /*
 106  * This funcion reads the *physical* memory. The f_pos points directly to the
 107  * memory location.
 108  */
 109 static ssize_t read_mem(struct file * file, char __user * buf,
 110                         size_t count, loff_t *ppos)
 111 {
 112         unsigned long p = *ppos;
 113         ssize_t read, sz;
 114         char *ptr;
 115
 116         if (!valid_phys_addr_range(p, count))
 117                 return -EFAULT;
 118         read = 0;
 119 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 120         /* we don't have page 0 mapped on sparc and m68k.. */
 121         if (p < PAGE_SIZE) {
 122                 sz = PAGE_SIZE - p;
 123                 if (sz > count)
 124                         sz = count;
 125                 if (sz > 0) {
 126                         if (clear_user(buf, sz))
 127                                 return -EFAULT;
 128                         buf += sz;
 129                         p += sz;
 130                         count -= sz;
 131                         read += sz;
 132                 }
 133         }
 134 #endif
 135
 136         while (count > 0) {
 137                 /*
 138                  * Handle first page in case it's not aligned
 139                  */
 140                 if (-p & (PAGE_SIZE - 1))
 141                         sz = -p & (PAGE_SIZE - 1);
 142                 else
 143                         sz = PAGE_SIZE;
 144
 145                 sz = min_t(unsigned long, sz, count);
 146
 147                 /*
 148                  * On ia64 if a page has been mapped somewhere as
 149                  * uncached, then it must also be accessed uncached
 150                  * by the kernel or data corruption may occur
 151                  */
 152                 ptr = xlate_dev_mem_ptr(p);
 153
 154                 if (copy_to_user(buf, ptr, sz))
 155                         return -EFAULT;
 156                 buf += sz;
 157                 p += sz;
 158                 count -= sz;
 159                 read += sz;
 160         }
 161
 162         *ppos += read;
 163         return read;
 164 }
 165
 166 static ssize_t write_mem(struct file * file, const char __user * buf,
 167                          size_t count, loff_t *ppos)
 168 {
 169         unsigned long p = *ppos;
 170         ssize_t written, sz;
 171         unsigned long copied;
 172         void *ptr;
 173
 174         if (!valid_phys_addr_range(p, count))
 175                 return -EFAULT;
 176
 177         written = 0;
 178
 179 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 180         /* we don't have page 0 mapped on sparc and m68k.. */
 181         if (p < PAGE_SIZE) {
 182                 unsigned long sz = PAGE_SIZE - p;
 183                 if (sz > count)
 184                         sz = count;
 185                 /* Hmm. Do something? */
 186                 buf += sz;
 187                 p += sz;
 188                 count -= sz;
 189                 written += sz;
 190         }
 191 #endif
 192
 193         while (count > 0) {
 194                 /*
 195                  * Handle first page in case it's not aligned
 196                  */
 197                 if (-p & (PAGE_SIZE - 1))
 198                         sz = -p & (PAGE_SIZE - 1);
 199                 else
 200                         sz = PAGE_SIZE;
 201
 202                 sz = min_t(unsigned long, sz, count);
 203
 204                 /*
 205                  * On ia64 if a page has been mapped somewhere as
 206                  * uncached, then it must also be accessed uncached
 207                  * by the kernel or data corruption may occur
 208                  */
 209                 ptr = xlate_dev_mem_ptr(p);
 210
 211                 copied = copy_from_user(ptr, buf, sz);
 212                 if (copied) {
 213                         written += sz - copied;
 214                         if (written)
 215                                 break;
 216                         return -EFAULT;
 217                 }
 218                 buf += sz;
 219                 p += sz;
 220                 count -= sz;
 221                 written += sz;
 222         }
 223
 224         *ppos += written;
 225         return written;
 226 }
 227
 228 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 229 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 230                                      unsigned long size, pgprot_t vma_prot)
 231 {
 232 #ifdef pgprot_noncached
 233         unsigned long offset = pfn << PAGE_SHIFT;
 234
 235         if (uncached_access(file, offset))
 236                 return pgprot_noncached(vma_prot);
 237 #endif
 238         return vma_prot;
 239 }
 240 #endif
 241
 242 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 243 {
 244         size_t size = vma->vm_end - vma->vm_start;
 245
 246         if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, size))
 247                 return -EINVAL;
 248
 249         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 250                                                  size,
 251                                                  vma->vm_page_prot);
 252
 253         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 254         if (remap_pfn_range(vma,
 255                             vma->vm_start,
 256                             vma->vm_pgoff,
 257                             size,
 258                             vma->vm_page_prot))
 259                 return -EAGAIN;
 260         return 0;
 261 }
 262
 263 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
 264 {
 265         unsigned long pfn;
 266
 267         /* Turn a kernel-virtual address into a physical page frame */
 268         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 269
 270         /*
 271          * RED-PEN: on some architectures there is more mapped memory
 272          * than available in mem_map which pfn_valid checks
 273          * for. Perhaps should add a new macro here.
 274          *
 275          * RED-PEN: vmalloc is not supported right now.
 276          */
 277         if (!pfn_valid(pfn))
 278                 return -EIO;
 279
 280         vma->vm_pgoff = pfn;
 281         return mmap_mem(file, vma);
 282 }
 283
 284 #ifdef CONFIG_CRASH_DUMP
 285 /*
 286  * Read memory corresponding to the old kernel.
 287  */
 288 static ssize_t read_oldmem(struct file *file, char __user *buf,
 289                                 size_t count, loff_t *ppos)
 290 {
 291         unsigned long pfn, offset;
 292         size_t read = 0, csize;
 293         int rc = 0;
 294
 295         while (count) {
 296                 pfn = *ppos / PAGE_SIZE;
 297                 if (pfn > saved_max_pfn)
 298                         return read;
 299
 300                 offset = (unsigned long)(*ppos % PAGE_SIZE);
 301                 if (count > PAGE_SIZE - offset)
 302                         csize = PAGE_SIZE - offset;
 303                 else
 304                         csize = count;
 305
 306                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
 307                 if (rc < 0)
 308                         return rc;
 309                 buf += csize;
 310                 *ppos += csize;
 311                 read += csize;
 312                 count -= csize;
 313         }
 314         return read;
 315 }
 316 #endif
 317
 318 extern long vread(char *buf, char *addr, unsigned long count);
 319 extern long vwrite(char *buf, char *addr, unsigned long count);
 320
 321 /*
 322  * This function reads the *virtual* memory as seen by the kernel.
 323  */
 324 static ssize_t read_kmem(struct file *file, char __user *buf,
 325                          size_t count, loff_t *ppos)
 326 {
 327         unsigned long p = *ppos;
 328         ssize_t low_count, read, sz;
 329         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 330
 331         read = 0;
 332         if (p < (unsigned long) high_memory) {
 333                 low_count = count;
 334                 if (count > (unsigned long) high_memory - p)
 335                         low_count = (unsigned long) high_memory - p;
 336
 337 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 338                 /* we don't have page 0 mapped on sparc and m68k.. */
 339                 if (p < PAGE_SIZE && low_count > 0) {
 340                         size_t tmp = PAGE_SIZE - p;
 341                         if (tmp > low_count) tmp = low_count;
 342                         if (clear_user(buf, tmp))
 343                                 return -EFAULT;
 344                         buf += tmp;
 345                         p += tmp;
 346                         read += tmp;
 347                         low_count -= tmp;
 348                         count -= tmp;
 349                 }
 350 #endif
 351                 while (low_count > 0) {
 352                         /*
 353                          * Handle first page in case it's not aligned
 354                          */
 355                         if (-p & (PAGE_SIZE - 1))
 356                                 sz = -p & (PAGE_SIZE - 1);
 357                         else
 358                                 sz = PAGE_SIZE;
 359
 360                         sz = min_t(unsigned long, sz, low_count);
 361
 362                         /*
 363                          * On ia64 if a page has been mapped somewhere as
 364                          * uncached, then it must also be accessed uncached
 365                          * by the kernel or data corruption may occur
 366                          */
 367                         kbuf = xlate_dev_kmem_ptr((char *)p);
 368
 369                         if (copy_to_user(buf, kbuf, sz))
 370                                 return -EFAULT;
 371                         buf += sz;
 372                         p += sz;
 373                         read += sz;
 374                         low_count -= sz;
 375                         count -= sz;
 376                 }
 377         }
 378
 379         if (count > 0) {
 380                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 381                 if (!kbuf)
 382                         return -ENOMEM;
 383                 while (count > 0) {
 384                         int len = count;
 385
 386                         if (len > PAGE_SIZE)
 387                                 len = PAGE_SIZE;
 388                         len = vread(kbuf, (char *)p, len);
 389                         if (!len)
 390                                 break;
 391                         if (copy_to_user(buf, kbuf, len)) {
 392                                 free_page((unsigned long)kbuf);
 393                                 return -EFAULT;
 394                         }
 395                         count -= len;
 396                         buf += len;
 397                         read += len;
 398                         p += len;
 399                 }
 400                 free_page((unsigned long)kbuf);
 401         }
 402         *ppos = p;
 403         return read;
 404 }
 405
 406
 407 static inline ssize_t
 408 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
 409               size_t count, loff_t *ppos)
 410 {
 411         ssize_t written, sz;
 412         unsigned long copied;
 413
 414         written = 0;
 415 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 416         /* we don't have page 0 mapped on sparc and m68k.. */
 417         if (realp < PAGE_SIZE) {
 418                 unsigned long sz = PAGE_SIZE - realp;
 419                 if (sz > count)
 420                         sz = count;
 421                 /* Hmm. Do something? */
 422                 buf += sz;
 423                 p += sz;
 424                 realp += sz;
 425                 count -= sz;
 426                 written += sz;
 427         }
 428 #endif
 429
 430         while (count > 0) {
 431                 char *ptr;
 432                 /*
 433                  * Handle first page in case it's not aligned
 434                  */
 435                 if (-realp & (PAGE_SIZE - 1))
 436                         sz = -realp & (PAGE_SIZE - 1);
 437                 else
 438                         sz = PAGE_SIZE;
 439
 440                 sz = min_t(unsigned long, sz, count);
 441
 442                 /*
 443                  * On ia64 if a page has been mapped somewhere as
 444                  * uncached, then it must also be accessed uncached
 445                  * by the kernel or data corruption may occur
 446                  */
 447                 ptr = xlate_dev_kmem_ptr(p);
 448
 449                 copied = copy_from_user(ptr, buf, sz);
 450                 if (copied) {
 451                         written += sz - copied;
 452                         if (written)
 453                                 break;
 454                         return -EFAULT;
 455                 }
 456                 buf += sz;
 457                 p += sz;
 458                 realp += sz;
 459                 count -= sz;
 460                 written += sz;
 461         }
 462
 463         *ppos += written;
 464         return written;
 465 }
 466
 467
 468 /*
 469  * This function writes to the *virtual* memory as seen by the kernel.
 470  */
 471 static ssize_t write_kmem(struct file * file, const char __user * buf,
 472                           size_t count, loff_t *ppos)
 473 {
 474         unsigned long p = *ppos;
 475         ssize_t wrote = 0;
 476         ssize_t virtr = 0;
 477         ssize_t written;
 478         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 479
 480         if (p < (unsigned long) high_memory) {
 481
 482                 wrote = count;
 483                 if (count > (unsigned long) high_memory - p)
 484                         wrote = (unsigned long) high_memory - p;
 485
 486                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
 487                 if (written != wrote)
 488                         return written;
 489                 wrote = written;
 490                 p += wrote;
 491                 buf += wrote;
 492                 count -= wrote;
 493         }
 494
 495         if (count > 0) {
 496                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 497                 if (!kbuf)
 498                         return wrote ? wrote : -ENOMEM;
 499                 while (count > 0) {
 500                         int len = count;
 501
 502                         if (len > PAGE_SIZE)
 503                                 len = PAGE_SIZE;
 504                         if (len) {
 505                                 written = copy_from_user(kbuf, buf, len);
 506                                 if (written) {
 507                                         if (wrote + virtr)
 508                                                 break;
 509                                         free_page((unsigned long)kbuf);
 510                                         return -EFAULT;
 511                                 }
 512                         }
 513                         len = vwrite(kbuf, (char *)p, len);
 514                         count -= len;
 515                         buf += len;
 516                         virtr += len;
 517                         p += len;
 518                 }
 519                 free_page((unsigned long)kbuf);
 520         }
 521
 522         *ppos = p;
 523         return virtr + wrote;
 524 }
 525
 526 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 527 static ssize_t read_port(struct file * file, char __user * buf,
 528                          size_t count, loff_t *ppos)
 529 {
 530         unsigned long i = *ppos;
 531         char __user *tmp = buf;
 532
 533         if (!access_ok(VERIFY_WRITE, buf, count))
 534                 return -EFAULT;
 535         while (count-- > 0 && i < 65536) {
 536                 if (__put_user(inb(i),tmp) < 0)
 537                         return -EFAULT;
 538                 i++;
 539                 tmp++;
 540         }
 541         *ppos = i;
 542         return tmp-buf;
 543 }
 544
 545 static ssize_t write_port(struct file * file, const char __user * buf,
 546                           size_t count, loff_t *ppos)
 547 {
 548         unsigned long i = *ppos;
 549         const char __user * tmp = buf;
 550
 551         if (!access_ok(VERIFY_READ,buf,count))
 552                 return -EFAULT;
 553         while (count-- > 0 && i < 65536) {
 554                 char c;
 555                 if (__get_user(c, tmp)) {
 556                         if (tmp > buf)
 557                                 break;
 558                         return -EFAULT;
 559                 }
 560                 outb(c,i);
 561                 i++;
 562                 tmp++;
 563         }
 564         *ppos = i;
 565         return tmp-buf;
 566 }
 567 #endif
 568
 569 static ssize_t read_null(struct file * file, char __user * buf,
 570                          size_t count, loff_t *ppos)
 571 {
 572         return 0;
 573 }
 574
 575 static ssize_t write_null(struct file * file, const char __user * buf,
 576                           size_t count, loff_t *ppos)
 577 {
 578         return count;
 579 }
 580
 581 #ifdef CONFIG_MMU
 582 /*
 583  * For fun, we are using the MMU for this.
 584  */
 585 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
 586 {
 587         struct mm_struct *mm;
 588         struct vm_area_struct * vma;
 589         unsigned long addr=(unsigned long)buf;
 590
 591         mm = current->mm;
 592         /* Oops, this was forgotten before. -ben */
 593         down_read(&mm->mmap_sem);
 594
 595         /* For private mappings, just map in zero pages. */
 596         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
 597                 unsigned long count;
 598
 599                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
 600                         goto out_up;
 601                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
 602                         break;
 603                 count = vma->vm_end - addr;
 604                 if (count > size)
 605                         count = size;
 606
 607                 zap_page_range(vma, addr, count, NULL);
 608                 zeromap_page_range(vma, addr, count, PAGE_COPY);
 609
 610                 size -= count;
 611                 buf += count;
 612                 addr += count;
 613                 if (size == 0)
 614                         goto out_up;
 615         }
 616
 617         up_read(&mm->mmap_sem);
 618
 619         /* The shared case is hard. Let's do the conventional zeroing. */
 620         do {
 621                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
 622                 if (unwritten)
 623                         return size + unwritten - PAGE_SIZE;
 624                 cond_resched();
 625                 buf += PAGE_SIZE;
 626                 size -= PAGE_SIZE;
 627         } while (size);
 628
 629         return size;
 630 out_up:
 631         up_read(&mm->mmap_sem);
 632         return size;
 633 }
 634
 635 static ssize_t read_zero(struct file * file, char __user * buf,
 636                          size_t count, loff_t *ppos)
 637 {
 638         unsigned long left, unwritten, written = 0;
 639
 640         if (!count)
 641                 return 0;
 642
 643         if (!access_ok(VERIFY_WRITE, buf, count))
 644                 return -EFAULT;
 645
 646         left = count;
 647
 648         /* do we want to be clever? Arbitrary cut-off */
 649         if (count >= PAGE_SIZE*4) {
 650                 unsigned long partial;
 651
 652                 /* How much left of the page? */
 653                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
 654                 unwritten = clear_user(buf, partial);
 655                 written = partial - unwritten;
 656                 if (unwritten)
 657                         goto out;
 658                 left -= partial;
 659                 buf += partial;
 660                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
 661                 written += (left & PAGE_MASK) - unwritten;
 662                 if (unwritten)
 663                         goto out;
 664                 buf += left & PAGE_MASK;
 665                 left &= ~PAGE_MASK;
 666         }
 667         unwritten = clear_user(buf, left);
 668         written += left - unwritten;
 669 out:
 670         return written ? written : -EFAULT;
 671 }
 672
 673 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 674 {
 675         if (vma->vm_flags & VM_SHARED)
 676                 return shmem_zero_setup(vma);
 677         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
 678                 return -EAGAIN;
 679         return 0;
 680 }
 681 #else /* CONFIG_MMU */
 682 static ssize_t read_zero(struct file * file, char * buf,
 683                          size_t count, loff_t *ppos)
 684 {
 685         size_t todo = count;
 686
 687         while (todo) {
 688                 size_t chunk = todo;
 689
 690                 if (chunk > 4096)
 691                         chunk = 4096;   /* Just for latency reasons */
 692                 if (clear_user(buf, chunk))
 693                         return -EFAULT;
 694                 buf += chunk;
 695                 todo -= chunk;
 696                 cond_resched();
 697         }
 698         return count;
 699 }
 700
 701 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 702 {
 703         return -ENOSYS;
 704 }
 705 #endif /* CONFIG_MMU */
 706
 707 static ssize_t write_full(struct file * file, const char __user * buf,
 708                           size_t count, loff_t *ppos)
 709 {
 710         return -ENOSPC;
 711 }
 712
 713 /*
 714  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 715  * can fopen() both devices with "a" now.  This was previously impossible.
 716  * -- SRB.
 717  */
 718
 719 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
 720 {
 721         return file->f_pos = 0;
 722 }
 723
 724 /*
 725  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 726  * check against negative addresses: they are ok. The return value is weird,
 727  * though, in that case (0).
 728  *
 729  * also note that seeking relative to the "end of file" isn't supported:
 730  * it has no meaning, so it returns -EINVAL.
 731  */
 732 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
 733 {
 734         loff_t ret;
 735
 736         mutex_lock(&file->f_dentry->d_inode->i_mutex);
 737         switch (orig) {
 738                 case 0:
 739                         file->f_pos = offset;
 740                         ret = file->f_pos;
 741                         force_successful_syscall_return();
 742                         break;
 743                 case 1:
 744                         file->f_pos += offset;
 745                         ret = file->f_pos;
 746                         force_successful_syscall_return();
 747                         break;
 748                 default:
 749                         ret = -EINVAL;
 750         }
 751         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 752         return ret;
 753 }
 754
 755 static int open_port(struct inode * inode, struct file * filp)
 756 {
 757         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 758 }
 759
 760 #define zero_lseek      null_lseek
 761 #define full_lseek      null_lseek
 762 #define write_zero      write_null
 763 #define read_full       read_zero
 764 #define open_mem        open_port
 765 #define open_kmem       open_mem
 766 #define open_oldmem     open_mem
 767
 768 static struct file_operations mem_fops = {
 769         .llseek         = memory_lseek,
 770         .read           = read_mem,
 771         .write          = write_mem,
 772         .mmap           = mmap_mem,
 773         .open           = open_mem,
 774 };
 775
 776 static struct file_operations kmem_fops = {
 777         .llseek         = memory_lseek,
 778         .read           = read_kmem,
 779         .write          = write_kmem,
 780         .mmap           = mmap_kmem,
 781         .open           = open_kmem,
 782 };
 783
 784 static struct file_operations null_fops = {
 785         .llseek         = null_lseek,
 786         .read           = read_null,
 787         .write          = write_null,
 788 };
 789
 790 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 791 static struct file_operations port_fops = {
 792         .llseek         = memory_lseek,
 793         .read           = read_port,
 794         .write          = write_port,
 795         .open           = open_port,
 796 };
 797 #endif
 798
 799 static struct file_operations zero_fops = {
 800         .llseek         = zero_lseek,
 801         .read           = read_zero,
 802         .write          = write_zero,
 803         .mmap           = mmap_zero,
 804 };
 805
 806 static struct backing_dev_info zero_bdi = {
 807         .capabilities   = BDI_CAP_MAP_COPY,
 808 };
 809
 810 static struct file_operations full_fops = {
 811         .llseek         = full_lseek,
 812         .read           = read_full,
 813         .write          = write_full,
 814 };
 815
 816 #ifdef CONFIG_CRASH_DUMP
 817 static struct file_operations oldmem_fops = {
 818         .read   = read_oldmem,
 819         .open   = open_oldmem,
 820 };
 821 #endif
 822
 823 static ssize_t kmsg_write(struct file * file, const char __user * buf,
 824                           size_t count, loff_t *ppos)
 825 {
 826         char *tmp;
 827         ssize_t ret;
 828
 829         tmp = kmalloc(count + 1, GFP_KERNEL);
 830         if (tmp == NULL)
 831                 return -ENOMEM;
 832         ret = -EFAULT;
 833         if (!copy_from_user(tmp, buf, count)) {
 834                 tmp[count] = 0;
 835                 ret = printk("%s", tmp);
 836                 if (ret > count)
 837                         /* printk can add a prefix */
 838                         ret = count;
 839         }
 840         kfree(tmp);
 841         return ret;
 842 }
 843
 844 static struct file_operations kmsg_fops = {
 845         .write =        kmsg_write,
 846 };
 847
 848 static int memory_open(struct inode * inode, struct file * filp)
 849 {
 850         switch (iminor(inode)) {
 851                 case 1:
 852                         filp->f_op = &mem_fops;
 853                         break;
 854                 case 2:
 855                         filp->f_op = &kmem_fops;
 856                         break;
 857                 case 3:
 858                         filp->f_op = &null_fops;
 859                         break;
 860 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 861                 case 4:
 862                         filp->f_op = &port_fops;
 863                         break;
 864 #endif
 865                 case 5:
 866                         filp->f_mapping->backing_dev_info = &zero_bdi;
 867                         filp->f_op = &zero_fops;
 868                         break;
 869                 case 7:
 870                         filp->f_op = &full_fops;
 871                         break;
 872                 case 8:
 873                         filp->f_op = &random_fops;
 874                         break;
 875                 case 9:
 876                         filp->f_op = &urandom_fops;
 877                         break;
 878                 case 11:
 879                         filp->f_op = &kmsg_fops;
 880                         break;
 881 #ifdef CONFIG_CRASH_DUMP
 882                 case 12:
 883                         filp->f_op = &oldmem_fops;
 884                         break;
 885 #endif
 886                 default:
 887                         return -ENXIO;
 888         }
 889         if (filp->f_op && filp->f_op->open)
 890                 return filp->f_op->open(inode,filp);
 891         return 0;
 892 }
 893
 894 static struct file_operations memory_fops = {
 895         .open           = memory_open,  /* just a selector for the real open */
 896 };
 897
 898 static const struct {
 899         unsigned int            minor;
 900         char                    *name;
 901         umode_t                 mode;
 902         const struct file_operations    *fops;
 903 } devlist[] = { /* list of minor devices */
 904         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
 905         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
 906         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
 907 #if defined(CONFIG_ISA) || !defined(__mc68000__)
 908         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
 909 #endif
 910         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
 911         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
 912         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
 913         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
 914         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
 915 #ifdef CONFIG_CRASH_DUMP
 916         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
 917 #endif
 918 };
 919
 920 static struct class *mem_class;
 921
 922 static int __init chr_dev_init(void)
 923 {
 924         int i;
 925
 926         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 927                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 928
 929         mem_class = class_create(THIS_MODULE, "mem");
 930         for (i = 0; i < ARRAY_SIZE(devlist); i++) {
 931                 class_device_create(mem_class, NULL,
 932                                         MKDEV(MEM_MAJOR, devlist[i].minor),
 933                                         NULL, devlist[i].name);
 934                 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
 935                                 S_IFCHR | devlist[i].mode, devlist[i].name);
 936         }
 937
 938         return 0;
 939 }
 940
 941 fs_initcall(chr_dev_init);