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 mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
   9  */
  10
  11 #include <linux/mm.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/slab.h>
  14 #include <linux/vmalloc.h>
  15 #include <linux/mman.h>
  16 #include <linux/random.h>
  17 #include <linux/init.h>
  18 #include <linux/raw.h>
  19 #include <linux/tty.h>
  20 #include <linux/capability.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/device.h>
  23 #include <linux/highmem.h>
  24 #include <linux/crash_dump.h>
  25 #include <linux/backing-dev.h>
  26 #include <linux/bootmem.h>
  27 #include <linux/splice.h>
  28 #include <linux/pfn.h>
  29
  30 #include <asm/uaccess.h>
  31 #include <asm/io.h>
  32
  33 #ifdef CONFIG_IA64
  34 # include <linux/efi.h>
  35 #endif
  36
  37 static inline unsigned long size_inside_page(unsigned long start,
  38                                              unsigned long size)
  39 {
  40         unsigned long sz;
  41
  42         sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
  43
  44         return min(sz, size);
  45 }
  46
  47 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  48 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
  49 {
  50         return addr + count <= __pa(high_memory);
  51 }
  52
  53 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
  54 {
  55         return 1;
  56 }
  57 #endif
  58
  59 #ifdef CONFIG_STRICT_DEVMEM
  60 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  61 {
  62         u64 from = ((u64)pfn) << PAGE_SHIFT;
  63         u64 to = from + size;
  64         u64 cursor = from;
  65
  66         while (cursor < to) {
  67                 if (!devmem_is_allowed(pfn)) {
  68                         printk(KERN_INFO
  69                 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
  70                                 current->comm, from, to);
  71                         return 0;
  72                 }
  73                 cursor += PAGE_SIZE;
  74                 pfn++;
  75         }
  76         return 1;
  77 }
  78 #else
  79 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  80 {
  81         return 1;
  82 }
  83 #endif
  84
  85 void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
  86 {
  87 }
  88
  89 /*
  90  * This funcion reads the *physical* memory. The f_pos points directly to the
  91  * memory location.
  92  */
  93 static ssize_t read_mem(struct file *file, char __user *buf,
  94                         size_t count, loff_t *ppos)
  95 {
  96         unsigned long p = *ppos;
  97         ssize_t read, sz;
  98         char *ptr;
  99
 100         if (!valid_phys_addr_range(p, count))
 101                 return -EFAULT;
 102         read = 0;
 103 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 104         /* we don't have page 0 mapped on sparc and m68k.. */
 105         if (p < PAGE_SIZE) {
 106                 sz = size_inside_page(p, count);
 107                 if (sz > 0) {
 108                         if (clear_user(buf, sz))
 109                                 return -EFAULT;
 110                         buf += sz;
 111                         p += sz;
 112                         count -= sz;
 113                         read += sz;
 114                 }
 115         }
 116 #endif
 117
 118         while (count > 0) {
 119                 unsigned long remaining;
 120
 121                 sz = size_inside_page(p, count);
 122
 123                 if (!range_is_allowed(p >> PAGE_SHIFT, count))
 124                         return -EPERM;
 125
 126                 /*
 127                  * On ia64 if a page has been mapped somewhere as uncached, then
 128                  * it must also be accessed uncached by the kernel or data
 129                  * corruption may occur.
 130                  */
 131                 ptr = xlate_dev_mem_ptr(p);
 132                 if (!ptr)
 133                         return -EFAULT;
 134
 135                 remaining = copy_to_user(buf, ptr, sz);
 136                 unxlate_dev_mem_ptr(p, ptr);
 137                 if (remaining)
 138                         return -EFAULT;
 139
 140                 buf += sz;
 141                 p += sz;
 142                 count -= sz;
 143                 read += sz;
 144         }
 145
 146         *ppos += read;
 147         return read;
 148 }
 149
 150 static ssize_t write_mem(struct file *file, const char __user *buf,
 151                          size_t count, loff_t *ppos)
 152 {
 153         unsigned long p = *ppos;
 154         ssize_t written, sz;
 155         unsigned long copied;
 156         void *ptr;
 157
 158         if (!valid_phys_addr_range(p, count))
 159                 return -EFAULT;
 160
 161         written = 0;
 162
 163 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 164         /* we don't have page 0 mapped on sparc and m68k.. */
 165         if (p < PAGE_SIZE) {
 166                 sz = size_inside_page(p, count);
 167                 /* Hmm. Do something? */
 168                 buf += sz;
 169                 p += sz;
 170                 count -= sz;
 171                 written += sz;
 172         }
 173 #endif
 174
 175         while (count > 0) {
 176                 sz = size_inside_page(p, count);
 177
 178                 if (!range_is_allowed(p >> PAGE_SHIFT, sz))
 179                         return -EPERM;
 180
 181                 /*
 182                  * On ia64 if a page has been mapped somewhere as uncached, then
 183                  * it must also be accessed uncached by the kernel or data
 184                  * corruption may occur.
 185                  */
 186                 ptr = xlate_dev_mem_ptr(p);
 187                 if (!ptr) {
 188                         if (written)
 189                                 break;
 190                         return -EFAULT;
 191                 }
 192
 193                 copied = copy_from_user(ptr, buf, sz);
 194                 unxlate_dev_mem_ptr(p, ptr);
 195                 if (copied) {
 196                         written += sz - copied;
 197                         if (written)
 198                                 break;
 199                         return -EFAULT;
 200                 }
 201
 202                 buf += sz;
 203                 p += sz;
 204                 count -= sz;
 205                 written += sz;
 206         }
 207
 208         *ppos += written;
 209         return written;
 210 }
 211
 212 int __weak phys_mem_access_prot_allowed(struct file *file,
 213         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
 214 {
 215         return 1;
 216 }
 217
 218 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 219
 220 /*
 221  * Architectures vary in how they handle caching for addresses
 222  * outside of main memory.
 223  *
 224  */
 225 #ifdef pgprot_noncached
 226 static int uncached_access(struct file *file, unsigned long addr)
 227 {
 228 #if defined(CONFIG_IA64)
 229         /*
 230          * On ia64, we ignore O_DSYNC because we cannot tolerate memory
 231          * attribute aliases.
 232          */
 233         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
 234 #elif defined(CONFIG_MIPS)
 235         {
 236                 extern int __uncached_access(struct file *file,
 237                                              unsigned long addr);
 238
 239                 return __uncached_access(file, addr);
 240         }
 241 #else
 242         /*
 243          * Accessing memory above the top the kernel knows about or through a
 244          * file pointer
 245          * that was marked O_DSYNC will be done non-cached.
 246          */
 247         if (file->f_flags & O_DSYNC)
 248                 return 1;
 249         return addr >= __pa(high_memory);
 250 #endif
 251 }
 252 #endif
 253
 254 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 255                                      unsigned long size, pgprot_t vma_prot)
 256 {
 257 #ifdef pgprot_noncached
 258         unsigned long offset = pfn << PAGE_SHIFT;
 259
 260         if (uncached_access(file, offset))
 261                 return pgprot_noncached(vma_prot);
 262 #endif
 263         return vma_prot;
 264 }
 265 #endif
 266
 267 #ifndef CONFIG_MMU
 268 static unsigned long get_unmapped_area_mem(struct file *file,
 269                                            unsigned long addr,
 270                                            unsigned long len,
 271                                            unsigned long pgoff,
 272                                            unsigned long flags)
 273 {
 274         if (!valid_mmap_phys_addr_range(pgoff, len))
 275                 return (unsigned long) -EINVAL;
 276         return pgoff << PAGE_SHIFT;
 277 }
 278
 279 /* can't do an in-place private mapping if there's no MMU */
 280 static inline int private_mapping_ok(struct vm_area_struct *vma)
 281 {
 282         return vma->vm_flags & VM_MAYSHARE;
 283 }
 284 #else
 285 #define get_unmapped_area_mem   NULL
 286
 287 static inline int private_mapping_ok(struct vm_area_struct *vma)
 288 {
 289         return 1;
 290 }
 291 #endif
 292
 293 static const struct vm_operations_struct mmap_mem_ops = {
 294 #ifdef CONFIG_HAVE_IOREMAP_PROT
 295         .access = generic_access_phys
 296 #endif
 297 };
 298
 299 static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 300 {
 301         size_t size = vma->vm_end - vma->vm_start;
 302
 303         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
 304                 return -EINVAL;
 305
 306         if (!private_mapping_ok(vma))
 307                 return -ENOSYS;
 308
 309         if (!range_is_allowed(vma->vm_pgoff, size))
 310                 return -EPERM;
 311
 312         if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
 313                                                 &vma->vm_page_prot))
 314                 return -EINVAL;
 315
 316         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 317                                                  size,
 318                                                  vma->vm_page_prot);
 319
 320         vma->vm_ops = &mmap_mem_ops;
 321
 322         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 323         if (remap_pfn_range(vma,
 324                             vma->vm_start,
 325                             vma->vm_pgoff,
 326                             size,
 327                             vma->vm_page_prot)) {
 328                 return -EAGAIN;
 329         }
 330         return 0;
 331 }
 332
 333 #ifdef CONFIG_DEVKMEM
 334 static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 335 {
 336         unsigned long pfn;
 337
 338         /* Turn a kernel-virtual address into a physical page frame */
 339         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 340
 341         /*
 342          * RED-PEN: on some architectures there is more mapped memory than
 343          * available in mem_map which pfn_valid checks for. Perhaps should add a
 344          * new macro here.
 345          *
 346          * RED-PEN: vmalloc is not supported right now.
 347          */
 348         if (!pfn_valid(pfn))
 349                 return -EIO;
 350
 351         vma->vm_pgoff = pfn;
 352         return mmap_mem(file, vma);
 353 }
 354 #endif
 355
 356 #ifdef CONFIG_CRASH_DUMP
 357 /*
 358  * Read memory corresponding to the old kernel.
 359  */
 360 static ssize_t read_oldmem(struct file *file, char __user *buf,
 361                                 size_t count, loff_t *ppos)
 362 {
 363         unsigned long pfn, offset;
 364         size_t read = 0, csize;
 365         int rc = 0;
 366
 367         while (count) {
 368                 pfn = *ppos / PAGE_SIZE;
 369                 if (pfn > saved_max_pfn)
 370                         return read;
 371
 372                 offset = (unsigned long)(*ppos % PAGE_SIZE);
 373                 if (count > PAGE_SIZE - offset)
 374                         csize = PAGE_SIZE - offset;
 375                 else
 376                         csize = count;
 377
 378                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
 379                 if (rc < 0)
 380                         return rc;
 381                 buf += csize;
 382                 *ppos += csize;
 383                 read += csize;
 384                 count -= csize;
 385         }
 386         return read;
 387 }
 388 #endif
 389
 390 #ifdef CONFIG_DEVKMEM
 391 /*
 392  * This function reads the *virtual* memory as seen by the kernel.
 393  */
 394 static ssize_t read_kmem(struct file *file, char __user *buf,
 395                          size_t count, loff_t *ppos)
 396 {
 397         unsigned long p = *ppos;
 398         ssize_t low_count, read, sz;
 399         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 400         int err = 0;
 401
 402         read = 0;
 403         if (p < (unsigned long) high_memory) {
 404                 low_count = count;
 405                 if (count > (unsigned long)high_memory - p)
 406                         low_count = (unsigned long)high_memory - p;
 407
 408 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 409                 /* we don't have page 0 mapped on sparc and m68k.. */
 410                 if (p < PAGE_SIZE && low_count > 0) {
 411                         sz = size_inside_page(p, low_count);
 412                         if (clear_user(buf, sz))
 413                                 return -EFAULT;
 414                         buf += sz;
 415                         p += sz;
 416                         read += sz;
 417                         low_count -= sz;
 418                         count -= sz;
 419                 }
 420 #endif
 421                 while (low_count > 0) {
 422                         sz = size_inside_page(p, low_count);
 423
 424                         /*
 425                          * On ia64 if a page has been mapped somewhere as
 426                          * uncached, then it must also be accessed uncached
 427                          * by the kernel or data corruption may occur
 428                          */
 429                         kbuf = xlate_dev_kmem_ptr((char *)p);
 430
 431                         if (copy_to_user(buf, kbuf, sz))
 432                                 return -EFAULT;
 433                         buf += sz;
 434                         p += sz;
 435                         read += sz;
 436                         low_count -= sz;
 437                         count -= sz;
 438                 }
 439         }
 440
 441         if (count > 0) {
 442                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 443                 if (!kbuf)
 444                         return -ENOMEM;
 445                 while (count > 0) {
 446                         sz = size_inside_page(p, count);
 447                         if (!is_vmalloc_or_module_addr((void *)p)) {
 448                                 err = -ENXIO;
 449                                 break;
 450                         }
 451                         sz = vread(kbuf, (char *)p, sz);
 452                         if (!sz)
 453                                 break;
 454                         if (copy_to_user(buf, kbuf, sz)) {
 455                                 err = -EFAULT;
 456                                 break;
 457                         }
 458                         count -= sz;
 459                         buf += sz;
 460                         read += sz;
 461                         p += sz;
 462                 }
 463                 free_page((unsigned long)kbuf);
 464         }
 465         *ppos = p;
 466         return read ? read : err;
 467 }
 468
 469
 470 static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
 471                                 size_t count, loff_t *ppos)
 472 {
 473         ssize_t written, sz;
 474         unsigned long copied;
 475
 476         written = 0;
 477 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 478         /* we don't have page 0 mapped on sparc and m68k.. */
 479         if (p < PAGE_SIZE) {
 480                 sz = size_inside_page(p, count);
 481                 /* Hmm. Do something? */
 482                 buf += sz;
 483                 p += sz;
 484                 count -= sz;
 485                 written += sz;
 486         }
 487 #endif
 488
 489         while (count > 0) {
 490                 char *ptr;
 491
 492                 sz = size_inside_page(p, count);
 493
 494                 /*
 495                  * On ia64 if a page has been mapped somewhere as uncached, then
 496                  * it must also be accessed uncached by the kernel or data
 497                  * corruption may occur.
 498                  */
 499                 ptr = xlate_dev_kmem_ptr((char *)p);
 500
 501                 copied = copy_from_user(ptr, buf, sz);
 502                 if (copied) {
 503                         written += sz - copied;
 504                         if (written)
 505                                 break;
 506                         return -EFAULT;
 507                 }
 508                 buf += sz;
 509                 p += sz;
 510                 count -= sz;
 511                 written += sz;
 512         }
 513
 514         *ppos += written;
 515         return written;
 516 }
 517
 518 /*
 519  * This function writes to the *virtual* memory as seen by the kernel.
 520  */
 521 static ssize_t write_kmem(struct file *file, const char __user *buf,
 522                           size_t count, loff_t *ppos)
 523 {
 524         unsigned long p = *ppos;
 525         ssize_t wrote = 0;
 526         ssize_t virtr = 0;
 527         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 528         int err = 0;
 529
 530         if (p < (unsigned long) high_memory) {
 531                 unsigned long to_write = min_t(unsigned long, count,
 532                                                (unsigned long)high_memory - p);
 533                 wrote = do_write_kmem(p, buf, to_write, ppos);
 534                 if (wrote != to_write)
 535                         return wrote;
 536                 p += wrote;
 537                 buf += wrote;
 538                 count -= wrote;
 539         }
 540
 541         if (count > 0) {
 542                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 543                 if (!kbuf)
 544                         return wrote ? wrote : -ENOMEM;
 545                 while (count > 0) {
 546                         unsigned long sz = size_inside_page(p, count);
 547                         unsigned long n;
 548
 549                         if (!is_vmalloc_or_module_addr((void *)p)) {
 550                                 err = -ENXIO;
 551                                 break;
 552                         }
 553                         n = copy_from_user(kbuf, buf, sz);
 554                         if (n) {
 555                                 err = -EFAULT;
 556                                 break;
 557                         }
 558                         vwrite(kbuf, (char *)p, sz);
 559                         count -= sz;
 560                         buf += sz;
 561                         virtr += sz;
 562                         p += sz;
 563                 }
 564                 free_page((unsigned long)kbuf);
 565         }
 566
 567         *ppos = p;
 568         return virtr + wrote ? : err;
 569 }
 570 #endif
 571
 572 #ifdef CONFIG_DEVPORT
 573 static ssize_t read_port(struct file *file, char __user *buf,
 574                          size_t count, loff_t *ppos)
 575 {
 576         unsigned long i = *ppos;
 577         char __user *tmp = buf;
 578
 579         if (!access_ok(VERIFY_WRITE, buf, count))
 580                 return -EFAULT;
 581         while (count-- > 0 && i < 65536) {
 582                 if (__put_user(inb(i), tmp) < 0)
 583                         return -EFAULT;
 584                 i++;
 585                 tmp++;
 586         }
 587         *ppos = i;
 588         return tmp-buf;
 589 }
 590
 591 static ssize_t write_port(struct file *file, const char __user *buf,
 592                           size_t count, loff_t *ppos)
 593 {
 594         unsigned long i = *ppos;
 595         const char __user * tmp = buf;
 596
 597         if (!access_ok(VERIFY_READ, buf, count))
 598                 return -EFAULT;
 599         while (count-- > 0 && i < 65536) {
 600                 char c;
 601                 if (__get_user(c, tmp)) {
 602                         if (tmp > buf)
 603                                 break;
 604                         return -EFAULT;
 605                 }
 606                 outb(c, i);
 607                 i++;
 608                 tmp++;
 609         }
 610         *ppos = i;
 611         return tmp-buf;
 612 }
 613 #endif
 614
 615 static ssize_t read_null(struct file *file, char __user *buf,
 616                          size_t count, loff_t *ppos)
 617 {
 618         return 0;
 619 }
 620
 621 static ssize_t write_null(struct file *file, const char __user *buf,
 622                           size_t count, loff_t *ppos)
 623 {
 624         return count;
 625 }
 626
 627 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 628                         struct splice_desc *sd)
 629 {
 630         return sd->len;
 631 }
 632
 633 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
 634                                  loff_t *ppos, size_t len, unsigned int flags)
 635 {
 636         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 637 }
 638
 639 static ssize_t read_zero(struct file *file, char __user *buf,
 640                          size_t count, loff_t *ppos)
 641 {
 642         size_t written;
 643
 644         if (!count)
 645                 return 0;
 646
 647         if (!access_ok(VERIFY_WRITE, buf, count))
 648                 return -EFAULT;
 649
 650         written = 0;
 651         while (count) {
 652                 unsigned long unwritten;
 653                 size_t chunk = count;
 654
 655                 if (chunk > PAGE_SIZE)
 656                         chunk = PAGE_SIZE;      /* Just for latency reasons */
 657                 unwritten = __clear_user(buf, chunk);
 658                 written += chunk - unwritten;
 659                 if (unwritten)
 660                         break;
 661                 if (signal_pending(current))
 662                         return written ? written : -ERESTARTSYS;
 663                 buf += chunk;
 664                 count -= chunk;
 665                 cond_resched();
 666         }
 667         return written ? written : -EFAULT;
 668 }
 669
 670 static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 671 {
 672 #ifndef CONFIG_MMU
 673         return -ENOSYS;
 674 #endif
 675         if (vma->vm_flags & VM_SHARED)
 676                 return shmem_zero_setup(vma);
 677         return 0;
 678 }
 679
 680 static ssize_t write_full(struct file *file, const char __user *buf,
 681                           size_t count, loff_t *ppos)
 682 {
 683         return -ENOSPC;
 684 }
 685
 686 /*
 687  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 688  * can fopen() both devices with "a" now.  This was previously impossible.
 689  * -- SRB.
 690  */
 691 static loff_t null_lseek(struct file *file, loff_t offset, int orig)
 692 {
 693         return file->f_pos = 0;
 694 }
 695
 696 /*
 697  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 698  * check against negative addresses: they are ok. The return value is weird,
 699  * though, in that case (0).
 700  *
 701  * also note that seeking relative to the "end of file" isn't supported:
 702  * it has no meaning, so it returns -EINVAL.
 703  */
 704 static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 705 {
 706         loff_t ret;
 707
 708         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
 709         switch (orig) {
 710         case SEEK_CUR:
 711                 offset += file->f_pos;
 712         case SEEK_SET:
 713                 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
 714                 if ((unsigned long long)offset >= ~0xFFFULL) {
 715                         ret = -EOVERFLOW;
 716                         break;
 717                 }
 718                 file->f_pos = offset;
 719                 ret = file->f_pos;
 720                 force_successful_syscall_return();
 721                 break;
 722         default:
 723                 ret = -EINVAL;
 724         }
 725         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
 726         return ret;
 727 }
 728
 729 static int open_port(struct inode * inode, struct file * filp)
 730 {
 731         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 732 }
 733
 734 #define zero_lseek      null_lseek
 735 #define full_lseek      null_lseek
 736 #define write_zero      write_null
 737 #define read_full       read_zero
 738 #define open_mem        open_port
 739 #define open_kmem       open_mem
 740 #define open_oldmem     open_mem
 741
 742 static const struct file_operations mem_fops = {
 743         .llseek         = memory_lseek,
 744         .read           = read_mem,
 745         .write          = write_mem,
 746         .mmap           = mmap_mem,
 747         .open           = open_mem,
 748         .get_unmapped_area = get_unmapped_area_mem,
 749 };
 750
 751 #ifdef CONFIG_DEVKMEM
 752 static const struct file_operations kmem_fops = {
 753         .llseek         = memory_lseek,
 754         .read           = read_kmem,
 755         .write          = write_kmem,
 756         .mmap           = mmap_kmem,
 757         .open           = open_kmem,
 758         .get_unmapped_area = get_unmapped_area_mem,
 759 };
 760 #endif
 761
 762 static const struct file_operations null_fops = {
 763         .llseek         = null_lseek,
 764         .read           = read_null,
 765         .write          = write_null,
 766         .splice_write   = splice_write_null,
 767 };
 768
 769 #ifdef CONFIG_DEVPORT
 770 static const struct file_operations port_fops = {
 771         .llseek         = memory_lseek,
 772         .read           = read_port,
 773         .write          = write_port,
 774         .open           = open_port,
 775 };
 776 #endif
 777
 778 static const struct file_operations zero_fops = {
 779         .llseek         = zero_lseek,
 780         .read           = read_zero,
 781         .write          = write_zero,
 782         .mmap           = mmap_zero,
 783 };
 784
 785 /*
 786  * capabilities for /dev/zero
 787  * - permits private mappings, "copies" are taken of the source of zeros
 788  * - no writeback happens
 789  */
 790 static struct backing_dev_info zero_bdi = {
 791         .name           = "char/mem",
 792         .capabilities   = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,
 793 };
 794
 795 static const struct file_operations full_fops = {
 796         .llseek         = full_lseek,
 797         .read           = read_full,
 798         .write          = write_full,
 799 };
 800
 801 #ifdef CONFIG_CRASH_DUMP
 802 static const struct file_operations oldmem_fops = {
 803         .read   = read_oldmem,
 804         .open   = open_oldmem,
 805         .llseek = default_llseek,
 806 };
 807 #endif
 808
 809 static ssize_t kmsg_write(struct file *file, const char __user *buf,
 810                           size_t count, loff_t *ppos)
 811 {
 812         char *tmp;
 813         ssize_t ret;
 814
 815         tmp = kmalloc(count + 1, GFP_KERNEL);
 816         if (tmp == NULL)
 817                 return -ENOMEM;
 818         ret = -EFAULT;
 819         if (!copy_from_user(tmp, buf, count)) {
 820                 tmp[count] = 0;
 821                 ret = printk("%s", tmp);
 822                 if (ret > count)
 823                         /* printk can add a prefix */
 824                         ret = count;
 825         }
 826         kfree(tmp);
 827         return ret;
 828 }
 829
 830 static const struct file_operations kmsg_fops = {
 831         .write = kmsg_write,
 832         .llseek = noop_llseek,
 833 };
 834
 835 static const struct memdev {
 836         const char *name;
 837         mode_t mode;
 838         const struct file_operations *fops;
 839         struct backing_dev_info *dev_info;
 840 } devlist[] = {
 841          [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
 842 #ifdef CONFIG_DEVKMEM
 843          [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 844 #endif
 845          [3] = { "null", 0666, &null_fops, NULL },
 846 #ifdef CONFIG_DEVPORT
 847          [4] = { "port", 0, &port_fops, NULL },
 848 #endif
 849          [5] = { "zero", 0666, &zero_fops, &zero_bdi },
 850          [7] = { "full", 0666, &full_fops, NULL },
 851          [8] = { "random", 0666, &random_fops, NULL },
 852          [9] = { "urandom", 0666, &urandom_fops, NULL },
 853         [11] = { "kmsg", 0, &kmsg_fops, NULL },
 854 #ifdef CONFIG_CRASH_DUMP
 855         [12] = { "oldmem", 0, &oldmem_fops, NULL },
 856 #endif
 857 };
 858
 859 static int memory_open(struct inode *inode, struct file *filp)
 860 {
 861         int minor;
 862         const struct memdev *dev;
 863
 864         minor = iminor(inode);
 865         if (minor >= ARRAY_SIZE(devlist))
 866                 return -ENXIO;
 867
 868         dev = &devlist[minor];
 869         if (!dev->fops)
 870                 return -ENXIO;
 871
 872         filp->f_op = dev->fops;
 873         if (dev->dev_info)
 874                 filp->f_mapping->backing_dev_info = dev->dev_info;
 875
 876         /* Is /dev/mem or /dev/kmem ? */
 877         if (dev->dev_info == &directly_mappable_cdev_bdi)
 878                 filp->f_mode |= FMODE_UNSIGNED_OFFSET;
 879
 880         if (dev->fops->open)
 881                 return dev->fops->open(inode, filp);
 882
 883         return 0;
 884 }
 885
 886 static const struct file_operations memory_fops = {
 887         .open = memory_open,
 888         .llseek = noop_llseek,
 889 };
 890
 891 static char *mem_devnode(struct device *dev, mode_t *mode)
 892 {
 893         if (mode && devlist[MINOR(dev->devt)].mode)
 894                 *mode = devlist[MINOR(dev->devt)].mode;
 895         return NULL;
 896 }
 897
 898 static struct class *mem_class;
 899
 900 static int __init chr_dev_init(void)
 901 {
 902         int minor;
 903         int err;
 904
 905         err = bdi_init(&zero_bdi);
 906         if (err)
 907                 return err;
 908
 909         if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
 910                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 911
 912         mem_class = class_create(THIS_MODULE, "mem");
 913         if (IS_ERR(mem_class))
 914                 return PTR_ERR(mem_class);
 915
 916         mem_class->devnode = mem_devnode;
 917         for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
 918                 if (!devlist[minor].name)
 919                         continue;
 920                 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
 921                               NULL, devlist[minor].name);
 922         }
 923
 924         return tty_init();
 925 }
 926
 927 fs_initcall(chr_dev_init);