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