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   1 /*
   2  *  linux/drivers/char/mem.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  Added devfs support.
   7  *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
   8  *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
   9  */
  10
  11 #include <linux/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 /*
  38  * Architectures vary in how they handle caching for addresses
  39  * outside of main memory.
  40  *
  41  */
  42 static inline int uncached_access(struct file *file, unsigned long addr)
  43 {
  44 #if defined(__i386__) && !defined(__arch_um__)
  45         /*
  46          * On the PPro and successors, the MTRRs are used to set
  47          * memory types for physical addresses outside main memory,
  48          * so blindly setting PCD or PWT on those pages is wrong.
  49          * For Pentiums and earlier, the surround logic should disable
  50          * caching for the high addresses through the KEN pin, but
  51          * we maintain the tradition of paranoia in this code.
  52          */
  53         if (file->f_flags & O_SYNC)
  54                 return 1;
  55         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
  56                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
  57                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
  58                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
  59           && addr >= __pa(high_memory);
  60 #elif defined(__x86_64__) && !defined(__arch_um__)
  61         /*
  62          * This is broken because it can generate memory type aliases,
  63          * which can cause cache corruptions
  64          * But it is only available for root and we have to be bug-to-bug
  65          * compatible with i386.
  66          */
  67         if (file->f_flags & O_SYNC)
  68                 return 1;
  69         /* same behaviour as i386. PAT always set to cached and MTRRs control the
  70            caching behaviour.
  71            Hopefully a full PAT implementation will fix that soon. */
  72         return 0;
  73 #elif defined(CONFIG_IA64)
  74         /*
  75          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
  76          */
  77         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
  78 #elif defined(CONFIG_MIPS)
  79         {
  80                 extern int __uncached_access(struct file *file,
  81                                              unsigned long addr);
  82
  83                 return __uncached_access(file, addr);
  84         }
  85 #else
  86         /*
  87          * Accessing memory above the top the kernel knows about or through a file pointer
  88          * that was marked O_SYNC will be done non-cached.
  89          */
  90         if (file->f_flags & O_SYNC)
  91                 return 1;
  92         return addr >= __pa(high_memory);
  93 #endif
  94 }
  95
  96 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  97 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
  98 {
  99         if (addr + count > __pa(high_memory))
 100                 return 0;
 101
 102         return 1;
 103 }
 104
 105 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 106 {
 107         return 1;
 108 }
 109 #endif
 110
 111 #ifdef CONFIG_NONPROMISC_DEVMEM
 112 static inline int range_is_allowed(unsigned long from, unsigned long to)
 113 {
 114         unsigned long cursor;
 115
 116         cursor = from >> PAGE_SHIFT;
 117         while ((cursor << PAGE_SHIFT) < to) {
 118                 if (!devmem_is_allowed(cursor)) {
 119                         printk(KERN_INFO "Program %s tried to read /dev/mem "
 120                                 "between %lx->%lx.\n",
 121                                 current->comm, from, to);
 122                         return 0;
 123                 }
 124                 cursor++;
 125         }
 126         return 1;
 127 }
 128 #else
 129 static inline int range_is_allowed(unsigned long from, unsigned long to)
 130 {
 131         return 1;
 132 }
 133 #endif
 134
 135 /*
 136  * This funcion reads the *physical* memory. The f_pos points directly to the
 137  * memory location.
 138  */
 139 static ssize_t read_mem(struct file * file, char __user * buf,
 140                         size_t count, loff_t *ppos)
 141 {
 142         unsigned long p = *ppos;
 143         ssize_t read, sz;
 144         char *ptr;
 145
 146         if (!valid_phys_addr_range(p, count))
 147                 return -EFAULT;
 148         read = 0;
 149 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 150         /* we don't have page 0 mapped on sparc and m68k.. */
 151         if (p < PAGE_SIZE) {
 152                 sz = PAGE_SIZE - p;
 153                 if (sz > count)
 154                         sz = count;
 155                 if (sz > 0) {
 156                         if (clear_user(buf, sz))
 157                                 return -EFAULT;
 158                         buf += sz;
 159                         p += sz;
 160                         count -= sz;
 161                         read += sz;
 162                 }
 163         }
 164 #endif
 165
 166         while (count > 0) {
 167                 /*
 168                  * Handle first page in case it's not aligned
 169                  */
 170                 if (-p & (PAGE_SIZE - 1))
 171                         sz = -p & (PAGE_SIZE - 1);
 172                 else
 173                         sz = PAGE_SIZE;
 174
 175                 sz = min_t(unsigned long, sz, count);
 176
 177                 /*
 178                  * On ia64 if a page has been mapped somewhere as
 179                  * uncached, then it must also be accessed uncached
 180                  * by the kernel or data corruption may occur
 181                  */
 182                 ptr = xlate_dev_mem_ptr(p);
 183
 184                 if (!range_is_allowed(p, p+count))
 185                         return -EPERM;
 186                 if (copy_to_user(buf, ptr, sz))
 187                         return -EFAULT;
 188                 buf += sz;
 189                 p += sz;
 190                 count -= sz;
 191                 read += sz;
 192         }
 193
 194         *ppos += read;
 195         return read;
 196 }
 197
 198 static ssize_t write_mem(struct file * file, const char __user * buf,
 199                          size_t count, loff_t *ppos)
 200 {
 201         unsigned long p = *ppos;
 202         ssize_t written, sz;
 203         unsigned long copied;
 204         void *ptr;
 205
 206         if (!valid_phys_addr_range(p, count))
 207                 return -EFAULT;
 208
 209         written = 0;
 210
 211 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 212         /* we don't have page 0 mapped on sparc and m68k.. */
 213         if (p < PAGE_SIZE) {
 214                 unsigned long sz = PAGE_SIZE - p;
 215                 if (sz > count)
 216                         sz = count;
 217                 /* Hmm. Do something? */
 218                 buf += sz;
 219                 p += sz;
 220                 count -= sz;
 221                 written += sz;
 222         }
 223 #endif
 224
 225         while (count > 0) {
 226                 /*
 227                  * Handle first page in case it's not aligned
 228                  */
 229                 if (-p & (PAGE_SIZE - 1))
 230                         sz = -p & (PAGE_SIZE - 1);
 231                 else
 232                         sz = PAGE_SIZE;
 233
 234                 sz = min_t(unsigned long, sz, count);
 235
 236                 /*
 237                  * On ia64 if a page has been mapped somewhere as
 238                  * uncached, then it must also be accessed uncached
 239                  * by the kernel or data corruption may occur
 240                  */
 241                 ptr = xlate_dev_mem_ptr(p);
 242
 243                 if (!range_is_allowed(p, p+sz))
 244                         return -EPERM;
 245                 copied = copy_from_user(ptr, buf, sz);
 246                 if (copied) {
 247                         written += sz - copied;
 248                         if (written)
 249                                 break;
 250                         return -EFAULT;
 251                 }
 252                 buf += sz;
 253                 p += sz;
 254                 count -= sz;
 255                 written += sz;
 256         }
 257
 258         *ppos += written;
 259         return written;
 260 }
 261
 262 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 263 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 264                                      unsigned long size, pgprot_t vma_prot)
 265 {
 266 #ifdef pgprot_noncached
 267         unsigned long offset = pfn << PAGE_SHIFT;
 268
 269         if (uncached_access(file, offset))
 270                 return pgprot_noncached(vma_prot);
 271 #endif
 272         return vma_prot;
 273 }
 274 #endif
 275
 276 #ifndef CONFIG_MMU
 277 static unsigned long get_unmapped_area_mem(struct file *file,
 278                                            unsigned long addr,
 279                                            unsigned long len,
 280                                            unsigned long pgoff,
 281                                            unsigned long flags)
 282 {
 283         if (!valid_mmap_phys_addr_range(pgoff, len))
 284                 return (unsigned long) -EINVAL;
 285         return pgoff << PAGE_SHIFT;
 286 }
 287
 288 /* can't do an in-place private mapping if there's no MMU */
 289 static inline int private_mapping_ok(struct vm_area_struct *vma)
 290 {
 291         return vma->vm_flags & VM_MAYSHARE;
 292 }
 293 #else
 294 #define get_unmapped_area_mem   NULL
 295
 296 static inline int private_mapping_ok(struct vm_area_struct *vma)
 297 {
 298         return 1;
 299 }
 300 #endif
 301
 302 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 303 {
 304         size_t size = vma->vm_end - vma->vm_start;
 305
 306         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
 307                 return -EINVAL;
 308
 309         if (!private_mapping_ok(vma))
 310                 return -ENOSYS;
 311
 312         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 313                                                  size,
 314                                                  vma->vm_page_prot);
 315
 316         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 317         if (remap_pfn_range(vma,
 318                             vma->vm_start,
 319                             vma->vm_pgoff,
 320                             size,
 321                             vma->vm_page_prot))
 322                 return -EAGAIN;
 323         return 0;
 324 }
 325
 326 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
 327 {
 328         unsigned long pfn;
 329
 330         /* Turn a kernel-virtual address into a physical page frame */
 331         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 332
 333         /*
 334          * RED-PEN: on some architectures there is more mapped memory
 335          * than available in mem_map which pfn_valid checks
 336          * for. Perhaps should add a new macro here.
 337          *
 338          * RED-PEN: vmalloc is not supported right now.
 339          */
 340         if (!pfn_valid(pfn))
 341                 return -EIO;
 342
 343         vma->vm_pgoff = pfn;
 344         return mmap_mem(file, vma);
 345 }
 346
 347 #ifdef CONFIG_CRASH_DUMP
 348 /*
 349  * Read memory corresponding to the old kernel.
 350  */
 351 static ssize_t read_oldmem(struct file *file, char __user *buf,
 352                                 size_t count, loff_t *ppos)
 353 {
 354         unsigned long pfn, offset;
 355         size_t read = 0, csize;
 356         int rc = 0;
 357
 358         while (count) {
 359                 pfn = *ppos / PAGE_SIZE;
 360                 if (pfn > saved_max_pfn)
 361                         return read;
 362
 363                 offset = (unsigned long)(*ppos % PAGE_SIZE);
 364                 if (count > PAGE_SIZE - offset)
 365                         csize = PAGE_SIZE - offset;
 366                 else
 367                         csize = count;
 368
 369                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
 370                 if (rc < 0)
 371                         return rc;
 372                 buf += csize;
 373                 *ppos += csize;
 374                 read += csize;
 375                 count -= csize;
 376         }
 377         return read;
 378 }
 379 #endif
 380
 381 extern long vread(char *buf, char *addr, unsigned long count);
 382 extern long vwrite(char *buf, char *addr, unsigned long count);
 383
 384 /*
 385  * This function reads the *virtual* memory as seen by the kernel.
 386  */
 387 static ssize_t read_kmem(struct file *file, char __user *buf,
 388                          size_t count, loff_t *ppos)
 389 {
 390         unsigned long p = *ppos;
 391         ssize_t low_count, read, sz;
 392         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 393
 394         read = 0;
 395         if (p < (unsigned long) high_memory) {
 396                 low_count = count;
 397                 if (count > (unsigned long) high_memory - p)
 398                         low_count = (unsigned long) high_memory - p;
 399
 400 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 401                 /* we don't have page 0 mapped on sparc and m68k.. */
 402                 if (p < PAGE_SIZE && low_count > 0) {
 403                         size_t tmp = PAGE_SIZE - p;
 404                         if (tmp > low_count) tmp = low_count;
 405                         if (clear_user(buf, tmp))
 406                                 return -EFAULT;
 407                         buf += tmp;
 408                         p += tmp;
 409                         read += tmp;
 410                         low_count -= tmp;
 411                         count -= tmp;
 412                 }
 413 #endif
 414                 while (low_count > 0) {
 415                         /*
 416                          * Handle first page in case it's not aligned
 417                          */
 418                         if (-p & (PAGE_SIZE - 1))
 419                                 sz = -p & (PAGE_SIZE - 1);
 420                         else
 421                                 sz = PAGE_SIZE;
 422
 423                         sz = min_t(unsigned long, sz, 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                         int len = count;
 448
 449                         if (len > PAGE_SIZE)
 450                                 len = PAGE_SIZE;
 451                         len = vread(kbuf, (char *)p, len);
 452                         if (!len)
 453                                 break;
 454                         if (copy_to_user(buf, kbuf, len)) {
 455                                 free_page((unsigned long)kbuf);
 456                                 return -EFAULT;
 457                         }
 458                         count -= len;
 459                         buf += len;
 460                         read += len;
 461                         p += len;
 462                 }
 463                 free_page((unsigned long)kbuf);
 464         }
 465         *ppos = p;
 466         return read;
 467 }
 468
 469
 470 static inline ssize_t
 471 do_write_kmem(void *p, unsigned long realp, 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 (realp < PAGE_SIZE) {
 481                 unsigned long sz = PAGE_SIZE - realp;
 482                 if (sz > count)
 483                         sz = count;
 484                 /* Hmm. Do something? */
 485                 buf += sz;
 486                 p += sz;
 487                 realp += sz;
 488                 count -= sz;
 489                 written += sz;
 490         }
 491 #endif
 492
 493         while (count > 0) {
 494                 char *ptr;
 495                 /*
 496                  * Handle first page in case it's not aligned
 497                  */
 498                 if (-realp & (PAGE_SIZE - 1))
 499                         sz = -realp & (PAGE_SIZE - 1);
 500                 else
 501                         sz = PAGE_SIZE;
 502
 503                 sz = min_t(unsigned long, sz, count);
 504
 505                 /*
 506                  * On ia64 if a page has been mapped somewhere as
 507                  * uncached, then it must also be accessed uncached
 508                  * by the kernel or data corruption may occur
 509                  */
 510                 ptr = xlate_dev_kmem_ptr(p);
 511
 512                 copied = copy_from_user(ptr, buf, sz);
 513                 if (copied) {
 514                         written += sz - copied;
 515                         if (written)
 516                                 break;
 517                         return -EFAULT;
 518                 }
 519                 buf += sz;
 520                 p += sz;
 521                 realp += sz;
 522                 count -= sz;
 523                 written += sz;
 524         }
 525
 526         *ppos += written;
 527         return written;
 528 }
 529
 530
 531 /*
 532  * This function writes to the *virtual* memory as seen by the kernel.
 533  */
 534 static ssize_t write_kmem(struct file * file, const char __user * buf,
 535                           size_t count, loff_t *ppos)
 536 {
 537         unsigned long p = *ppos;
 538         ssize_t wrote = 0;
 539         ssize_t virtr = 0;
 540         ssize_t written;
 541         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 542
 543         if (p < (unsigned long) high_memory) {
 544
 545                 wrote = count;
 546                 if (count > (unsigned long) high_memory - p)
 547                         wrote = (unsigned long) high_memory - p;
 548
 549                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
 550                 if (written != wrote)
 551                         return written;
 552                 wrote = written;
 553                 p += wrote;
 554                 buf += wrote;
 555                 count -= wrote;
 556         }
 557
 558         if (count > 0) {
 559                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 560                 if (!kbuf)
 561                         return wrote ? wrote : -ENOMEM;
 562                 while (count > 0) {
 563                         int len = count;
 564
 565                         if (len > PAGE_SIZE)
 566                                 len = PAGE_SIZE;
 567                         if (len) {
 568                                 written = copy_from_user(kbuf, buf, len);
 569                                 if (written) {
 570                                         if (wrote + virtr)
 571                                                 break;
 572                                         free_page((unsigned long)kbuf);
 573                                         return -EFAULT;
 574                                 }
 575                         }
 576                         len = vwrite(kbuf, (char *)p, len);
 577                         count -= len;
 578                         buf += len;
 579                         virtr += len;
 580                         p += len;
 581                 }
 582                 free_page((unsigned long)kbuf);
 583         }
 584
 585         *ppos = p;
 586         return virtr + wrote;
 587 }
 588
 589 #ifdef CONFIG_DEVPORT
 590 static ssize_t read_port(struct file * file, char __user * buf,
 591                          size_t count, loff_t *ppos)
 592 {
 593         unsigned long i = *ppos;
 594         char __user *tmp = buf;
 595
 596         if (!access_ok(VERIFY_WRITE, buf, count))
 597                 return -EFAULT;
 598         while (count-- > 0 && i < 65536) {
 599                 if (__put_user(inb(i),tmp) < 0)
 600                         return -EFAULT;
 601                 i++;
 602                 tmp++;
 603         }
 604         *ppos = i;
 605         return tmp-buf;
 606 }
 607
 608 static ssize_t write_port(struct file * file, const char __user * buf,
 609                           size_t count, loff_t *ppos)
 610 {
 611         unsigned long i = *ppos;
 612         const char __user * tmp = buf;
 613
 614         if (!access_ok(VERIFY_READ,buf,count))
 615                 return -EFAULT;
 616         while (count-- > 0 && i < 65536) {
 617                 char c;
 618                 if (__get_user(c, tmp)) {
 619                         if (tmp > buf)
 620                                 break;
 621                         return -EFAULT;
 622                 }
 623                 outb(c,i);
 624                 i++;
 625                 tmp++;
 626         }
 627         *ppos = i;
 628         return tmp-buf;
 629 }
 630 #endif
 631
 632 static ssize_t read_null(struct file * file, char __user * buf,
 633                          size_t count, loff_t *ppos)
 634 {
 635         return 0;
 636 }
 637
 638 static ssize_t write_null(struct file * file, const char __user * buf,
 639                           size_t count, loff_t *ppos)
 640 {
 641         return count;
 642 }
 643
 644 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 645                         struct splice_desc *sd)
 646 {
 647         return sd->len;
 648 }
 649
 650 static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
 651                                  loff_t *ppos, size_t len, unsigned int flags)
 652 {
 653         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 654 }
 655
 656 static ssize_t read_zero(struct file * file, char __user * buf,
 657                          size_t count, loff_t *ppos)
 658 {
 659         size_t written;
 660
 661         if (!count)
 662                 return 0;
 663
 664         if (!access_ok(VERIFY_WRITE, buf, count))
 665                 return -EFAULT;
 666
 667         written = 0;
 668         while (count) {
 669                 unsigned long unwritten;
 670                 size_t chunk = count;
 671
 672                 if (chunk > PAGE_SIZE)
 673                         chunk = PAGE_SIZE;      /* Just for latency reasons */
 674                 unwritten = clear_user(buf, chunk);
 675                 written += chunk - unwritten;
 676                 if (unwritten)
 677                         break;
 678                 buf += chunk;
 679                 count -= chunk;
 680                 cond_resched();
 681         }
 682         return written ? written : -EFAULT;
 683 }
 684
 685 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 686 {
 687 #ifndef CONFIG_MMU
 688         return -ENOSYS;
 689 #endif
 690         if (vma->vm_flags & VM_SHARED)
 691                 return shmem_zero_setup(vma);
 692         return 0;
 693 }
 694
 695 static ssize_t write_full(struct file * file, const char __user * buf,
 696                           size_t count, loff_t *ppos)
 697 {
 698         return -ENOSPC;
 699 }
 700
 701 /*
 702  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 703  * can fopen() both devices with "a" now.  This was previously impossible.
 704  * -- SRB.
 705  */
 706
 707 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
 708 {
 709         return file->f_pos = 0;
 710 }
 711
 712 /*
 713  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 714  * check against negative addresses: they are ok. The return value is weird,
 715  * though, in that case (0).
 716  *
 717  * also note that seeking relative to the "end of file" isn't supported:
 718  * it has no meaning, so it returns -EINVAL.
 719  */
 720 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
 721 {
 722         loff_t ret;
 723
 724         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
 725         switch (orig) {
 726                 case 0:
 727                         file->f_pos = offset;
 728                         ret = file->f_pos;
 729                         force_successful_syscall_return();
 730                         break;
 731                 case 1:
 732                         file->f_pos += offset;
 733                         ret = file->f_pos;
 734                         force_successful_syscall_return();
 735                         break;
 736                 default:
 737                         ret = -EINVAL;
 738         }
 739         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
 740         return ret;
 741 }
 742
 743 static int open_port(struct inode * inode, struct file * filp)
 744 {
 745         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 746 }
 747
 748 #define zero_lseek      null_lseek
 749 #define full_lseek      null_lseek
 750 #define write_zero      write_null
 751 #define read_full       read_zero
 752 #define open_mem        open_port
 753 #define open_kmem       open_mem
 754 #define open_oldmem     open_mem
 755
 756 static const struct file_operations mem_fops = {
 757         .llseek         = memory_lseek,
 758         .read           = read_mem,
 759         .write          = write_mem,
 760         .mmap           = mmap_mem,
 761         .open           = open_mem,
 762         .get_unmapped_area = get_unmapped_area_mem,
 763 };
 764
 765 static const struct file_operations kmem_fops = {
 766         .llseek         = memory_lseek,
 767         .read           = read_kmem,
 768         .write          = write_kmem,
 769         .mmap           = mmap_kmem,
 770         .open           = open_kmem,
 771         .get_unmapped_area = get_unmapped_area_mem,
 772 };
 773
 774 static const struct file_operations null_fops = {
 775         .llseek         = null_lseek,
 776         .read           = read_null,
 777         .write          = write_null,
 778         .splice_write   = splice_write_null,
 779 };
 780
 781 #ifdef CONFIG_DEVPORT
 782 static const struct file_operations port_fops = {
 783         .llseek         = memory_lseek,
 784         .read           = read_port,
 785         .write          = write_port,
 786         .open           = open_port,
 787 };
 788 #endif
 789
 790 static const struct file_operations zero_fops = {
 791         .llseek         = zero_lseek,
 792         .read           = read_zero,
 793         .write          = write_zero,
 794         .mmap           = mmap_zero,
 795 };
 796
 797 /*
 798  * capabilities for /dev/zero
 799  * - permits private mappings, "copies" are taken of the source of zeros
 800  */
 801 static struct backing_dev_info zero_bdi = {
 802         .capabilities   = BDI_CAP_MAP_COPY,
 803 };
 804
 805 static const struct file_operations full_fops = {
 806         .llseek         = full_lseek,
 807         .read           = read_full,
 808         .write          = write_full,
 809 };
 810
 811 #ifdef CONFIG_CRASH_DUMP
 812 static const struct file_operations oldmem_fops = {
 813         .read   = read_oldmem,
 814         .open   = open_oldmem,
 815 };
 816 #endif
 817
 818 static ssize_t kmsg_write(struct file * file, const char __user * buf,
 819                           size_t count, loff_t *ppos)
 820 {
 821         char *tmp;
 822         ssize_t ret;
 823
 824         tmp = kmalloc(count + 1, GFP_KERNEL);
 825         if (tmp == NULL)
 826                 return -ENOMEM;
 827         ret = -EFAULT;
 828         if (!copy_from_user(tmp, buf, count)) {
 829                 tmp[count] = 0;
 830                 ret = printk("%s", tmp);
 831                 if (ret > count)
 832                         /* printk can add a prefix */
 833                         ret = count;
 834         }
 835         kfree(tmp);
 836         return ret;
 837 }
 838
 839 static const struct file_operations kmsg_fops = {
 840         .write =        kmsg_write,
 841 };
 842
 843 static int memory_open(struct inode * inode, struct file * filp)
 844 {
 845         switch (iminor(inode)) {
 846                 case 1:
 847                         filp->f_op = &mem_fops;
 848                         filp->f_mapping->backing_dev_info =
 849                                 &directly_mappable_cdev_bdi;
 850                         break;
 851                 case 2:
 852                         filp->f_op = &kmem_fops;
 853                         filp->f_mapping->backing_dev_info =
 854                                 &directly_mappable_cdev_bdi;
 855                         break;
 856                 case 3:
 857                         filp->f_op = &null_fops;
 858                         break;
 859 #ifdef CONFIG_DEVPORT
 860                 case 4:
 861                         filp->f_op = &port_fops;
 862                         break;
 863 #endif
 864                 case 5:
 865                         filp->f_mapping->backing_dev_info = &zero_bdi;
 866                         filp->f_op = &zero_fops;
 867                         break;
 868                 case 7:
 869                         filp->f_op = &full_fops;
 870                         break;
 871                 case 8:
 872                         filp->f_op = &random_fops;
 873                         break;
 874                 case 9:
 875                         filp->f_op = &urandom_fops;
 876                         break;
 877                 case 11:
 878                         filp->f_op = &kmsg_fops;
 879                         break;
 880 #ifdef CONFIG_CRASH_DUMP
 881                 case 12:
 882                         filp->f_op = &oldmem_fops;
 883                         break;
 884 #endif
 885                 default:
 886                         return -ENXIO;
 887         }
 888         if (filp->f_op && filp->f_op->open)
 889                 return filp->f_op->open(inode,filp);
 890         return 0;
 891 }
 892
 893 static const struct file_operations memory_fops = {
 894         .open           = memory_open,  /* just a selector for the real open */
 895 };
 896
 897 static const struct {
 898         unsigned int            minor;
 899         char                    *name;
 900         umode_t                 mode;
 901         const struct file_operations    *fops;
 902 } devlist[] = { /* list of minor devices */
 903         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
 904         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
 905         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
 906 #ifdef CONFIG_DEVPORT
 907         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
 908 #endif
 909         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
 910         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
 911         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
 912         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
 913         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
 914 #ifdef CONFIG_CRASH_DUMP
 915         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
 916 #endif
 917 };
 918
 919 static struct class *mem_class;
 920
 921 static int __init chr_dev_init(void)
 922 {
 923         int i;
 924         int err;
 925
 926         err = bdi_init(&zero_bdi);
 927         if (err)
 928                 return err;
 929
 930         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 931                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 932
 933         mem_class = class_create(THIS_MODULE, "mem");
 934         for (i = 0; i < ARRAY_SIZE(devlist); i++)
 935                 device_create(mem_class, NULL,
 936                               MKDEV(MEM_MAJOR, devlist[i].minor),
 937                               devlist[i].name);
 938
 939         return 0;
 940 }
 941
 942 fs_initcall(chr_dev_init);