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 #include <linux/export.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 static inline unsigned long size_inside_page(unsigned long start,
  39                                              unsigned long size)
  40 {
  41         unsigned long sz;
  42
  43         sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
  44
  45         return min(sz, size);
  46 }
  47
  48 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  49 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
  50 {
  51         return addr + count <= __pa(high_memory);
  52 }
  53
  54 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
  55 {
  56         return 1;
  57 }
  58 #endif
  59
  60 #ifdef CONFIG_STRICT_DEVMEM
  61 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  62 {
  63         u64 from = ((u64)pfn) << PAGE_SHIFT;
  64         u64 to = from + size;
  65         u64 cursor = from;
  66
  67         while (cursor < to) {
  68                 if (!devmem_is_allowed(pfn)) {
  69                         printk(KERN_INFO
  70                 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
  71                                 current->comm, from, to);
  72                         return 0;
  73                 }
  74                 cursor += PAGE_SIZE;
  75                 pfn++;
  76         }
  77         return 1;
  78 }
  79 #else
  80 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  81 {
  82         return 1;
  83 }
  84 #endif
  85
  86 void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
  87 {
  88 }
  89
  90 /*
  91  * This funcion reads the *physical* memory. The f_pos points directly to the
  92  * memory location.
  93  */
  94 static ssize_t read_mem(struct file *file, char __user *buf,
  95                         size_t count, loff_t *ppos)
  96 {
  97         unsigned long p = *ppos;
  98         ssize_t read, sz;
  99         char *ptr;
 100
 101         if (!valid_phys_addr_range(p, count))
 102                 return -EFAULT;
 103         read = 0;
 104 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 105         /* we don't have page 0 mapped on sparc and m68k.. */
 106         if (p < PAGE_SIZE) {
 107                 sz = size_inside_page(p, count);
 108                 if (sz > 0) {
 109                         if (clear_user(buf, sz))
 110                                 return -EFAULT;
 111                         buf += sz;
 112                         p += sz;
 113                         count -= sz;
 114                         read += sz;
 115                 }
 116         }
 117 #endif
 118
 119         while (count > 0) {
 120                 unsigned long remaining;
 121
 122                 sz = size_inside_page(p, count);
 123
 124                 if (!range_is_allowed(p >> PAGE_SHIFT, count))
 125                         return -EPERM;
 126
 127                 /*
 128                  * On ia64 if a page has been mapped somewhere as uncached, then
 129                  * it must also be accessed uncached by the kernel or data
 130                  * corruption may occur.
 131                  */
 132                 ptr = xlate_dev_mem_ptr(p);
 133                 if (!ptr)
 134                         return -EFAULT;
 135
 136                 remaining = copy_to_user(buf, ptr, sz);
 137                 unxlate_dev_mem_ptr(p, ptr);
 138                 if (remaining)
 139                         return -EFAULT;
 140
 141                 buf += sz;
 142                 p += sz;
 143                 count -= sz;
 144                 read += sz;
 145         }
 146
 147         *ppos += read;
 148         return read;
 149 }
 150
 151 static ssize_t write_mem(struct file *file, const char __user *buf,
 152                          size_t count, loff_t *ppos)
 153 {
 154         unsigned long p = *ppos;
 155         ssize_t written, sz;
 156         unsigned long copied;
 157         void *ptr;
 158
 159         if (!valid_phys_addr_range(p, count))
 160                 return -EFAULT;
 161
 162         written = 0;
 163
 164 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 165         /* we don't have page 0 mapped on sparc and m68k.. */
 166         if (p < PAGE_SIZE) {
 167                 sz = size_inside_page(p, count);
 168                 /* Hmm. Do something? */
 169                 buf += sz;
 170                 p += sz;
 171                 count -= sz;
 172                 written += sz;
 173         }
 174 #endif
 175
 176         while (count > 0) {
 177                 sz = size_inside_page(p, count);
 178
 179                 if (!range_is_allowed(p >> PAGE_SHIFT, sz))
 180                         return -EPERM;
 181
 182                 /*
 183                  * On ia64 if a page has been mapped somewhere as uncached, then
 184                  * it must also be accessed uncached by the kernel or data
 185                  * corruption may occur.
 186                  */
 187                 ptr = xlate_dev_mem_ptr(p);
 188                 if (!ptr) {
 189                         if (written)
 190                                 break;
 191                         return -EFAULT;
 192                 }
 193
 194                 copied = copy_from_user(ptr, buf, sz);
 195                 unxlate_dev_mem_ptr(p, ptr);
 196                 if (copied) {
 197                         written += sz - copied;
 198                         if (written)
 199                                 break;
 200                         return -EFAULT;
 201                 }
 202
 203                 buf += sz;
 204                 p += sz;
 205                 count -= sz;
 206                 written += sz;
 207         }
 208
 209         *ppos += written;
 210         return written;
 211 }
 212
 213 int __weak phys_mem_access_prot_allowed(struct file *file,
 214         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
 215 {
 216         return 1;
 217 }
 218
 219 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 220
 221 /*
 222  * Architectures vary in how they handle caching for addresses
 223  * outside of main memory.
 224  *
 225  */
 226 #ifdef pgprot_noncached
 227 static int uncached_access(struct file *file, unsigned long addr)
 228 {
 229 #if defined(CONFIG_IA64)
 230         /*
 231          * On ia64, we ignore O_DSYNC because we cannot tolerate memory
 232          * attribute aliases.
 233          */
 234         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
 235 #elif defined(CONFIG_MIPS)
 236         {
 237                 extern int __uncached_access(struct file *file,
 238                                              unsigned long addr);
 239
 240                 return __uncached_access(file, addr);
 241         }
 242 #else
 243         /*
 244          * Accessing memory above the top the kernel knows about or through a
 245          * file pointer
 246          * that was marked O_DSYNC will be done non-cached.
 247          */
 248         if (file->f_flags & O_DSYNC)
 249                 return 1;
 250         return addr >= __pa(high_memory);
 251 #endif
 252 }
 253 #endif
 254
 255 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 256                                      unsigned long size, pgprot_t vma_prot)
 257 {
 258 #ifdef pgprot_noncached
 259         unsigned long offset = pfn << PAGE_SHIFT;
 260
 261         if (uncached_access(file, offset))
 262                 return pgprot_noncached(vma_prot);
 263 #endif
 264         return vma_prot;
 265 }
 266 #endif
 267
 268 #ifndef CONFIG_MMU
 269 static unsigned long get_unmapped_area_mem(struct file *file,
 270                                            unsigned long addr,
 271                                            unsigned long len,
 272                                            unsigned long pgoff,
 273                                            unsigned long flags)
 274 {
 275         if (!valid_mmap_phys_addr_range(pgoff, len))
 276                 return (unsigned long) -EINVAL;
 277         return pgoff << PAGE_SHIFT;
 278 }
 279
 280 /* can't do an in-place private mapping if there's no MMU */
 281 static inline int private_mapping_ok(struct vm_area_struct *vma)
 282 {
 283         return vma->vm_flags & VM_MAYSHARE;
 284 }
 285 #else
 286 #define get_unmapped_area_mem   NULL
 287
 288 static inline int private_mapping_ok(struct vm_area_struct *vma)
 289 {
 290         return 1;
 291 }
 292 #endif
 293
 294 static const struct vm_operations_struct mmap_mem_ops = {
 295 #ifdef CONFIG_HAVE_IOREMAP_PROT
 296         .access = generic_access_phys
 297 #endif
 298 };
 299
 300 static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 301 {
 302         size_t size = vma->vm_end - vma->vm_start;
 303
 304         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
 305                 return -EINVAL;
 306
 307         if (!private_mapping_ok(vma))
 308                 return -ENOSYS;
 309
 310         if (!range_is_allowed(vma->vm_pgoff, size))
 311                 return -EPERM;
 312
 313         if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
 314                                                 &vma->vm_page_prot))
 315                 return -EINVAL;
 316
 317         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 318                                                  size,
 319                                                  vma->vm_page_prot);
 320
 321         vma->vm_ops = &mmap_mem_ops;
 322
 323         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 324         if (remap_pfn_range(vma,
 325                             vma->vm_start,
 326                             vma->vm_pgoff,
 327                             size,
 328                             vma->vm_page_prot)) {
 329                 return -EAGAIN;
 330         }
 331         return 0;
 332 }
 333
 334 #ifdef CONFIG_DEVKMEM
 335 static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 336 {
 337         unsigned long pfn;
 338
 339         /* Turn a kernel-virtual address into a physical page frame */
 340         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 341
 342         /*
 343          * RED-PEN: on some architectures there is more mapped memory than
 344          * available in mem_map which pfn_valid checks for. Perhaps should add a
 345          * new macro here.
 346          *
 347          * RED-PEN: vmalloc is not supported right now.
 348          */
 349         if (!pfn_valid(pfn))
 350                 return -EIO;
 351
 352         vma->vm_pgoff = pfn;
 353         return mmap_mem(file, vma);
 354 }
 355 #endif
 356
 357 #ifdef CONFIG_CRASH_DUMP
 358 /*
 359  * Read memory corresponding to the old kernel.
 360  */
 361 static ssize_t read_oldmem(struct file *file, char __user *buf,
 362                                 size_t count, loff_t *ppos)
 363 {
 364         unsigned long pfn, offset;
 365         size_t read = 0, csize;
 366         int rc = 0;
 367
 368         while (count) {
 369                 pfn = *ppos / PAGE_SIZE;
 370                 if (pfn > saved_max_pfn)
 371                         return read;
 372
 373                 offset = (unsigned long)(*ppos % PAGE_SIZE);
 374                 if (count > PAGE_SIZE - offset)
 375                         csize = PAGE_SIZE - offset;
 376                 else
 377                         csize = count;
 378
 379                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
 380                 if (rc < 0)
 381                         return rc;
 382                 buf += csize;
 383                 *ppos += csize;
 384                 read += csize;
 385                 count -= csize;
 386         }
 387         return read;
 388 }
 389 #endif
 390
 391 #ifdef CONFIG_DEVKMEM
 392 /*
 393  * This function reads the *virtual* memory as seen by the kernel.
 394  */
 395 static ssize_t read_kmem(struct file *file, char __user *buf,
 396                          size_t count, loff_t *ppos)
 397 {
 398         unsigned long p = *ppos;
 399         ssize_t low_count, read, sz;
 400         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 401         int err = 0;
 402
 403         read = 0;
 404         if (p < (unsigned long) high_memory) {
 405                 low_count = count;
 406                 if (count > (unsigned long)high_memory - p)
 407                         low_count = (unsigned long)high_memory - p;
 408
 409 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 410                 /* we don't have page 0 mapped on sparc and m68k.. */
 411                 if (p < PAGE_SIZE && low_count > 0) {
 412                         sz = size_inside_page(p, low_count);
 413                         if (clear_user(buf, sz))
 414                                 return -EFAULT;
 415                         buf += sz;
 416                         p += sz;
 417                         read += sz;
 418                         low_count -= sz;
 419                         count -= sz;
 420                 }
 421 #endif
 422                 while (low_count > 0) {
 423                         sz = size_inside_page(p, low_count);
 424
 425                         /*
 426                          * On ia64 if a page has been mapped somewhere as
 427                          * uncached, then it must also be accessed uncached
 428                          * by the kernel or data corruption may occur
 429                          */
 430                         kbuf = xlate_dev_kmem_ptr((char *)p);
 431
 432                         if (copy_to_user(buf, kbuf, sz))
 433                                 return -EFAULT;
 434                         buf += sz;
 435                         p += sz;
 436                         read += sz;
 437                         low_count -= sz;
 438                         count -= sz;
 439                 }
 440         }
 441
 442         if (count > 0) {
 443                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 444                 if (!kbuf)
 445                         return -ENOMEM;
 446                 while (count > 0) {
 447                         sz = size_inside_page(p, count);
 448                         if (!is_vmalloc_or_module_addr((void *)p)) {
 449                                 err = -ENXIO;
 450                                 break;
 451                         }
 452                         sz = vread(kbuf, (char *)p, sz);
 453                         if (!sz)
 454                                 break;
 455                         if (copy_to_user(buf, kbuf, sz)) {
 456                                 err = -EFAULT;
 457                                 break;
 458                         }
 459                         count -= sz;
 460                         buf += sz;
 461                         read += sz;
 462                         p += sz;
 463                 }
 464                 free_page((unsigned long)kbuf);
 465         }
 466         *ppos = p;
 467         return read ? read : err;
 468 }
 469
 470
 471 static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
 472                                 size_t count, loff_t *ppos)
 473 {
 474         ssize_t written, sz;
 475         unsigned long copied;
 476
 477         written = 0;
 478 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 479         /* we don't have page 0 mapped on sparc and m68k.. */
 480         if (p < PAGE_SIZE) {
 481                 sz = size_inside_page(p, count);
 482                 /* Hmm. Do something? */
 483                 buf += sz;
 484                 p += sz;
 485                 count -= sz;
 486                 written += sz;
 487         }
 488 #endif
 489
 490         while (count > 0) {
 491                 char *ptr;
 492
 493                 sz = size_inside_page(p, count);
 494
 495                 /*
 496                  * On ia64 if a page has been mapped somewhere as uncached, then
 497                  * it must also be accessed uncached by the kernel or data
 498                  * corruption may occur.
 499                  */
 500                 ptr = xlate_dev_kmem_ptr((char *)p);
 501
 502                 copied = copy_from_user(ptr, buf, sz);
 503                 if (copied) {
 504                         written += sz - copied;
 505                         if (written)
 506                                 break;
 507                         return -EFAULT;
 508                 }
 509                 buf += sz;
 510                 p += sz;
 511                 count -= sz;
 512                 written += sz;
 513         }
 514
 515         *ppos += written;
 516         return written;
 517 }
 518
 519 /*
 520  * This function writes to the *virtual* memory as seen by the kernel.
 521  */
 522 static ssize_t write_kmem(struct file *file, const char __user *buf,
 523                           size_t count, loff_t *ppos)
 524 {
 525         unsigned long p = *ppos;
 526         ssize_t wrote = 0;
 527         ssize_t virtr = 0;
 528         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 529         int err = 0;
 530
 531         if (p < (unsigned long) high_memory) {
 532                 unsigned long to_write = min_t(unsigned long, count,
 533                                                (unsigned long)high_memory - p);
 534                 wrote = do_write_kmem(p, buf, to_write, ppos);
 535                 if (wrote != to_write)
 536                         return wrote;
 537                 p += wrote;
 538                 buf += wrote;
 539                 count -= wrote;
 540         }
 541
 542         if (count > 0) {
 543                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 544                 if (!kbuf)
 545                         return wrote ? wrote : -ENOMEM;
 546                 while (count > 0) {
 547                         unsigned long sz = size_inside_page(p, count);
 548                         unsigned long n;
 549
 550                         if (!is_vmalloc_or_module_addr((void *)p)) {
 551                                 err = -ENXIO;
 552                                 break;
 553                         }
 554                         n = copy_from_user(kbuf, buf, sz);
 555                         if (n) {
 556                                 err = -EFAULT;
 557                                 break;
 558                         }
 559                         vwrite(kbuf, (char *)p, sz);
 560                         count -= sz;
 561                         buf += sz;
 562                         virtr += sz;
 563                         p += sz;
 564                 }
 565                 free_page((unsigned long)kbuf);
 566         }
 567
 568         *ppos = p;
 569         return virtr + wrote ? : err;
 570 }
 571 #endif
 572
 573 #ifdef CONFIG_DEVPORT
 574 static ssize_t read_port(struct file *file, char __user *buf,
 575                          size_t count, loff_t *ppos)
 576 {
 577         unsigned long i = *ppos;
 578         char __user *tmp = buf;
 579
 580         if (!access_ok(VERIFY_WRITE, buf, count))
 581                 return -EFAULT;
 582         while (count-- > 0 && i < 65536) {
 583                 if (__put_user(inb(i), tmp) < 0)
 584                         return -EFAULT;
 585                 i++;
 586                 tmp++;
 587         }
 588         *ppos = i;
 589         return tmp-buf;
 590 }
 591
 592 static ssize_t write_port(struct file *file, const char __user *buf,
 593                           size_t count, loff_t *ppos)
 594 {
 595         unsigned long i = *ppos;
 596         const char __user * tmp = buf;
 597
 598         if (!access_ok(VERIFY_READ, buf, count))
 599                 return -EFAULT;
 600         while (count-- > 0 && i < 65536) {
 601                 char c;
 602                 if (__get_user(c, tmp)) {
 603                         if (tmp > buf)
 604                                 break;
 605                         return -EFAULT;
 606                 }
 607                 outb(c, i);
 608                 i++;
 609                 tmp++;
 610         }
 611         *ppos = i;
 612         return tmp-buf;
 613 }
 614 #endif
 615
 616 static ssize_t read_null(struct file *file, char __user *buf,
 617                          size_t count, loff_t *ppos)
 618 {
 619         return 0;
 620 }
 621
 622 static ssize_t write_null(struct file *file, const char __user *buf,
 623                           size_t count, loff_t *ppos)
 624 {
 625         return count;
 626 }
 627
 628 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 629                         struct splice_desc *sd)
 630 {
 631         return sd->len;
 632 }
 633
 634 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
 635                                  loff_t *ppos, size_t len, unsigned int flags)
 636 {
 637         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 638 }
 639
 640 static ssize_t read_zero(struct file *file, char __user *buf,
 641                          size_t count, loff_t *ppos)
 642 {
 643         size_t written;
 644
 645         if (!count)
 646                 return 0;
 647
 648         if (!access_ok(VERIFY_WRITE, buf, count))
 649                 return -EFAULT;
 650
 651         written = 0;
 652         while (count) {
 653                 unsigned long unwritten;
 654                 size_t chunk = count;
 655
 656                 if (chunk > PAGE_SIZE)
 657                         chunk = PAGE_SIZE;      /* Just for latency reasons */
 658                 unwritten = __clear_user(buf, chunk);
 659                 written += chunk - unwritten;
 660                 if (unwritten)
 661                         break;
 662                 if (signal_pending(current))
 663                         return written ? written : -ERESTARTSYS;
 664                 buf += chunk;
 665                 count -= chunk;
 666                 cond_resched();
 667         }
 668         return written ? written : -EFAULT;
 669 }
 670
 671 static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 672 {
 673 #ifndef CONFIG_MMU
 674         return -ENOSYS;
 675 #endif
 676         if (vma->vm_flags & VM_SHARED)
 677                 return shmem_zero_setup(vma);
 678         return 0;
 679 }
 680
 681 static ssize_t write_full(struct file *file, const char __user *buf,
 682                           size_t count, loff_t *ppos)
 683 {
 684         return -ENOSPC;
 685 }
 686
 687 /*
 688  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 689  * can fopen() both devices with "a" now.  This was previously impossible.
 690  * -- SRB.
 691  */
 692 static loff_t null_lseek(struct file *file, loff_t offset, int orig)
 693 {
 694         return file->f_pos = 0;
 695 }
 696
 697 /*
 698  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 699  * check against negative addresses: they are ok. The return value is weird,
 700  * though, in that case (0).
 701  *
 702  * also note that seeking relative to the "end of file" isn't supported:
 703  * it has no meaning, so it returns -EINVAL.
 704  */
 705 static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 706 {
 707         loff_t ret;
 708
 709         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
 710         switch (orig) {
 711         case SEEK_CUR:
 712                 offset += file->f_pos;
 713         case SEEK_SET:
 714                 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
 715                 if ((unsigned long long)offset >= ~0xFFFULL) {
 716                         ret = -EOVERFLOW;
 717                         break;
 718                 }
 719                 file->f_pos = offset;
 720                 ret = file->f_pos;
 721                 force_successful_syscall_return();
 722                 break;
 723         default:
 724                 ret = -EINVAL;
 725         }
 726         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
 727         return ret;
 728 }
 729
 730 static int open_port(struct inode * inode, struct file * filp)
 731 {
 732         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 733 }
 734
 735 #define zero_lseek      null_lseek
 736 #define full_lseek      null_lseek
 737 #define write_zero      write_null
 738 #define read_full       read_zero
 739 #define open_mem        open_port
 740 #define open_kmem       open_mem
 741 #define open_oldmem     open_mem
 742
 743 static const struct file_operations mem_fops = {
 744         .llseek         = memory_lseek,
 745         .read           = read_mem,
 746         .write          = write_mem,
 747         .mmap           = mmap_mem,
 748         .open           = open_mem,
 749         .get_unmapped_area = get_unmapped_area_mem,
 750 };
 751
 752 #ifdef CONFIG_DEVKMEM
 753 static const struct file_operations kmem_fops = {
 754         .llseek         = memory_lseek,
 755         .read           = read_kmem,
 756         .write          = write_kmem,
 757         .mmap           = mmap_kmem,
 758         .open           = open_kmem,
 759         .get_unmapped_area = get_unmapped_area_mem,
 760 };
 761 #endif
 762
 763 static const struct file_operations null_fops = {
 764         .llseek         = null_lseek,
 765         .read           = read_null,
 766         .write          = write_null,
 767         .splice_write   = splice_write_null,
 768 };
 769
 770 #ifdef CONFIG_DEVPORT
 771 static const struct file_operations port_fops = {
 772         .llseek         = memory_lseek,
 773         .read           = read_port,
 774         .write          = write_port,
 775         .open           = open_port,
 776 };
 777 #endif
 778
 779 static const struct file_operations zero_fops = {
 780         .llseek         = zero_lseek,
 781         .read           = read_zero,
 782         .write          = write_zero,
 783         .mmap           = mmap_zero,
 784 };
 785
 786 /*
 787  * capabilities for /dev/zero
 788  * - permits private mappings, "copies" are taken of the source of zeros
 789  * - no writeback happens
 790  */
 791 static struct backing_dev_info zero_bdi = {
 792         .name           = "char/mem",
 793         .capabilities   = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,
 794 };
 795
 796 static const struct file_operations full_fops = {
 797         .llseek         = full_lseek,
 798         .read           = read_full,
 799         .write          = write_full,
 800 };
 801
 802 #ifdef CONFIG_CRASH_DUMP
 803 static const struct file_operations oldmem_fops = {
 804         .read   = read_oldmem,
 805         .open   = open_oldmem,
 806         .llseek = default_llseek,
 807 };
 808 #endif
 809
 810 static ssize_t kmsg_writev(struct kiocb *iocb, const struct iovec *iv,
 811                            unsigned long count, loff_t pos)
 812 {
 813         char *line, *p;
 814         int i;
 815         ssize_t ret = -EFAULT;
 816         size_t len = iov_length(iv, count);
 817
 818         line = kmalloc(len + 1, GFP_KERNEL);
 819         if (line == NULL)
 820                 return -ENOMEM;
 821
 822         /*
 823          * copy all vectors into a single string, to ensure we do
 824          * not interleave our log line with other printk calls
 825          */
 826         p = line;
 827         for (i = 0; i < count; i++) {
 828                 if (copy_from_user(p, iv[i].iov_base, iv[i].iov_len))
 829                         goto out;
 830                 p += iv[i].iov_len;
 831         }
 832         p[0] = '\0';
 833
 834         ret = printk("%s", line);
 835         /* printk can add a prefix */
 836         if (ret > len)
 837                 ret = len;
 838 out:
 839         kfree(line);
 840         return ret;
 841 }
 842
 843 static const struct file_operations kmsg_fops = {
 844         .aio_write = kmsg_writev,
 845         .llseek = noop_llseek,
 846 };
 847
 848 static const struct memdev {
 849         const char *name;
 850         umode_t mode;
 851         const struct file_operations *fops;
 852         struct backing_dev_info *dev_info;
 853 } devlist[] = {
 854          [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
 855 #ifdef CONFIG_DEVKMEM
 856          [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 857 #endif
 858          [3] = { "null", 0666, &null_fops, NULL },
 859 #ifdef CONFIG_DEVPORT
 860          [4] = { "port", 0, &port_fops, NULL },
 861 #endif
 862          [5] = { "zero", 0666, &zero_fops, &zero_bdi },
 863          [7] = { "full", 0666, &full_fops, NULL },
 864          [8] = { "random", 0666, &random_fops, NULL },
 865          [9] = { "urandom", 0666, &urandom_fops, NULL },
 866         [11] = { "kmsg", 0, &kmsg_fops, NULL },
 867 #ifdef CONFIG_CRASH_DUMP
 868         [12] = { "oldmem", 0, &oldmem_fops, NULL },
 869 #endif
 870 };
 871
 872 static int memory_open(struct inode *inode, struct file *filp)
 873 {
 874         int minor;
 875         const struct memdev *dev;
 876
 877         minor = iminor(inode);
 878         if (minor >= ARRAY_SIZE(devlist))
 879                 return -ENXIO;
 880
 881         dev = &devlist[minor];
 882         if (!dev->fops)
 883                 return -ENXIO;
 884
 885         filp->f_op = dev->fops;
 886         if (dev->dev_info)
 887                 filp->f_mapping->backing_dev_info = dev->dev_info;
 888
 889         /* Is /dev/mem or /dev/kmem ? */
 890         if (dev->dev_info == &directly_mappable_cdev_bdi)
 891                 filp->f_mode |= FMODE_UNSIGNED_OFFSET;
 892
 893         if (dev->fops->open)
 894                 return dev->fops->open(inode, filp);
 895
 896         return 0;
 897 }
 898
 899 static const struct file_operations memory_fops = {
 900         .open = memory_open,
 901         .llseek = noop_llseek,
 902 };
 903
 904 static char *mem_devnode(struct device *dev, umode_t *mode)
 905 {
 906         if (mode && devlist[MINOR(dev->devt)].mode)
 907                 *mode = devlist[MINOR(dev->devt)].mode;
 908         return NULL;
 909 }
 910
 911 static struct class *mem_class;
 912
 913 static int __init chr_dev_init(void)
 914 {
 915         int minor;
 916         int err;
 917
 918         err = bdi_init(&zero_bdi);
 919         if (err)
 920                 return err;
 921
 922         if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
 923                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 924
 925         mem_class = class_create(THIS_MODULE, "mem");
 926         if (IS_ERR(mem_class))
 927                 return PTR_ERR(mem_class);
 928
 929         mem_class->devnode = mem_devnode;
 930         for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
 931                 if (!devlist[minor].name)
 932                         continue;
 933                 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
 934                               NULL, devlist[minor].name);
 935         }
 936
 937         return tty_init();
 938 }
 939
 940 fs_initcall(chr_dev_init);