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   1 /*
   2  *  linux/drivers/char/mem.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  Added devfs support.
   7  *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
   8  *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/mm.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/slab.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/mman.h>
  17 #include <linux/random.h>
  18 #include <linux/init.h>
  19 #include <linux/raw.h>
  20 #include <linux/tty.h>
  21 #include <linux/capability.h>
  22 #include <linux/smp_lock.h>
  23 #include <linux/devfs_fs_kernel.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/device.h>
  26 #include <linux/highmem.h>
  27 #include <linux/crash_dump.h>
  28 #include <linux/backing-dev.h>
  29
  30 #include <asm/uaccess.h>
  31 #include <asm/io.h>
  32
  33 #ifdef CONFIG_IA64
  34 # include <linux/efi.h>
  35 #endif
  36
  37 #if defined(CONFIG_S390_TAPE) && defined(CONFIG_S390_TAPE_CHAR)
  38 extern void tapechar_init(void);
  39 #endif
  40
  41 /*
  42  * Architectures vary in how they handle caching for addresses
  43  * outside of main memory.
  44  *
  45  */
  46 static inline int uncached_access(struct file *file, unsigned long addr)
  47 {
  48 #if defined(__i386__)
  49         /*
  50          * On the PPro and successors, the MTRRs are used to set
  51          * memory types for physical addresses outside main memory,
  52          * so blindly setting PCD or PWT on those pages is wrong.
  53          * For Pentiums and earlier, the surround logic should disable
  54          * caching for the high addresses through the KEN pin, but
  55          * we maintain the tradition of paranoia in this code.
  56          */
  57         if (file->f_flags & O_SYNC)
  58                 return 1;
  59         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
  60                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
  61                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
  62                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
  63           && addr >= __pa(high_memory);
  64 #elif defined(__x86_64__)
  65         /*
  66          * This is broken because it can generate memory type aliases,
  67          * which can cause cache corruptions
  68          * But it is only available for root and we have to be bug-to-bug
  69          * compatible with i386.
  70          */
  71         if (file->f_flags & O_SYNC)
  72                 return 1;
  73         /* same behaviour as i386. PAT always set to cached and MTRRs control the
  74            caching behaviour.
  75            Hopefully a full PAT implementation will fix that soon. */
  76         return 0;
  77 #elif defined(CONFIG_IA64)
  78         /*
  79          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
  80          */
  81         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
  82 #else
  83         /*
  84          * Accessing memory above the top the kernel knows about or through a file pointer
  85          * that was marked O_SYNC will be done non-cached.
  86          */
  87         if (file->f_flags & O_SYNC)
  88                 return 1;
  89         return addr >= __pa(high_memory);
  90 #endif
  91 }
  92
  93 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  94 static inline int valid_phys_addr_range(unsigned long addr, size_t *count)
  95 {
  96         unsigned long end_mem;
  97
  98         end_mem = __pa(high_memory);
  99         if (addr >= end_mem)
 100                 return 0;
 101
 102         if (*count > end_mem - addr)
 103                 *count = end_mem - addr;
 104
 105         return 1;
 106 }
 107 #endif
 108
 109 /*
 110  * This funcion reads the *physical* memory. The f_pos points directly to the
 111  * memory location.
 112  */
 113 static ssize_t read_mem(struct file * file, char __user * buf,
 114                         size_t count, loff_t *ppos)
 115 {
 116         unsigned long p = *ppos;
 117         ssize_t read, sz;
 118         char *ptr;
 119
 120         if (!valid_phys_addr_range(p, &count))
 121                 return -EFAULT;
 122         read = 0;
 123 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 124         /* we don't have page 0 mapped on sparc and m68k.. */
 125         if (p < PAGE_SIZE) {
 126                 sz = PAGE_SIZE - p;
 127                 if (sz > count)
 128                         sz = count;
 129                 if (sz > 0) {
 130                         if (clear_user(buf, sz))
 131                                 return -EFAULT;
 132                         buf += sz;
 133                         p += sz;
 134                         count -= sz;
 135                         read += sz;
 136                 }
 137         }
 138 #endif
 139
 140         while (count > 0) {
 141                 /*
 142                  * Handle first page in case it's not aligned
 143                  */
 144                 if (-p & (PAGE_SIZE - 1))
 145                         sz = -p & (PAGE_SIZE - 1);
 146                 else
 147                         sz = PAGE_SIZE;
 148
 149                 sz = min_t(unsigned long, sz, count);
 150
 151                 /*
 152                  * On ia64 if a page has been mapped somewhere as
 153                  * uncached, then it must also be accessed uncached
 154                  * by the kernel or data corruption may occur
 155                  */
 156                 ptr = xlate_dev_mem_ptr(p);
 157
 158                 if (copy_to_user(buf, ptr, sz))
 159                         return -EFAULT;
 160                 buf += sz;
 161                 p += sz;
 162                 count -= sz;
 163                 read += sz;
 164         }
 165
 166         *ppos += read;
 167         return read;
 168 }
 169
 170 static ssize_t write_mem(struct file * file, const char __user * buf,
 171                          size_t count, loff_t *ppos)
 172 {
 173         unsigned long p = *ppos;
 174         ssize_t written, sz;
 175         unsigned long copied;
 176         void *ptr;
 177
 178         if (!valid_phys_addr_range(p, &count))
 179                 return -EFAULT;
 180
 181         written = 0;
 182
 183 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 184         /* we don't have page 0 mapped on sparc and m68k.. */
 185         if (p < PAGE_SIZE) {
 186                 unsigned long sz = PAGE_SIZE - p;
 187                 if (sz > count)
 188                         sz = count;
 189                 /* Hmm. Do something? */
 190                 buf += sz;
 191                 p += sz;
 192                 count -= sz;
 193                 written += sz;
 194         }
 195 #endif
 196
 197         while (count > 0) {
 198                 /*
 199                  * Handle first page in case it's not aligned
 200                  */
 201                 if (-p & (PAGE_SIZE - 1))
 202                         sz = -p & (PAGE_SIZE - 1);
 203                 else
 204                         sz = PAGE_SIZE;
 205
 206                 sz = min_t(unsigned long, sz, count);
 207
 208                 /*
 209                  * On ia64 if a page has been mapped somewhere as
 210                  * uncached, then it must also be accessed uncached
 211                  * by the kernel or data corruption may occur
 212                  */
 213                 ptr = xlate_dev_mem_ptr(p);
 214
 215                 copied = copy_from_user(ptr, buf, sz);
 216                 if (copied) {
 217                         ssize_t ret;
 218
 219                         ret = written + (sz - copied);
 220                         if (ret)
 221                                 return ret;
 222                         return -EFAULT;
 223                 }
 224                 buf += sz;
 225                 p += sz;
 226                 count -= sz;
 227                 written += sz;
 228         }
 229
 230         *ppos += written;
 231         return written;
 232 }
 233
 234 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 235 {
 236 #if defined(__HAVE_PHYS_MEM_ACCESS_PROT)
 237         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 238
 239         vma->vm_page_prot = phys_mem_access_prot(file, offset,
 240                                                  vma->vm_end - vma->vm_start,
 241                                                  vma->vm_page_prot);
 242 #elif defined(pgprot_noncached)
 243         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 244         int uncached;
 245
 246         uncached = uncached_access(file, offset);
 247         if (uncached)
 248                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 249 #endif
 250
 251         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 252         if (remap_pfn_range(vma,
 253                             vma->vm_start,
 254                             vma->vm_pgoff,
 255                             vma->vm_end-vma->vm_start,
 256                             vma->vm_page_prot))
 257                 return -EAGAIN;
 258         return 0;
 259 }
 260
 261 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
 262 {
 263         unsigned long long val;
 264         /*
 265          * RED-PEN: on some architectures there is more mapped memory
 266          * than available in mem_map which pfn_valid checks
 267          * for. Perhaps should add a new macro here.
 268          *
 269          * RED-PEN: vmalloc is not supported right now.
 270          */
 271         if (!pfn_valid(vma->vm_pgoff))
 272                 return -EIO;
 273         val = (u64)vma->vm_pgoff << PAGE_SHIFT;
 274         vma->vm_pgoff = __pa(val) >> PAGE_SHIFT;
 275         return mmap_mem(file, vma);
 276 }
 277
 278 #ifdef CONFIG_CRASH_DUMP
 279 /*
 280  * Read memory corresponding to the old kernel.
 281  * If we are reading from the reserved section, which is
 282  * actually used by the current kernel, we just return zeroes.
 283  * Or if we are reading from the first 640k, we return from the
 284  * backed up area.
 285  */
 286 static ssize_t read_oldmem(struct file * file, char * buf,
 287                                 size_t count, loff_t *ppos)
 288 {
 289         unsigned long pfn;
 290         unsigned backup_start, backup_end, relocate_start;
 291         size_t read=0, csize;
 292
 293         backup_start = CRASH_BACKUP_BASE / PAGE_SIZE;
 294         backup_end = backup_start + (CRASH_BACKUP_SIZE / PAGE_SIZE);
 295         relocate_start = (CRASH_BACKUP_BASE + CRASH_BACKUP_SIZE) / PAGE_SIZE;
 296
 297         while(count) {
 298                 pfn = *ppos / PAGE_SIZE;
 299
 300                 csize = (count > PAGE_SIZE) ? PAGE_SIZE : count;
 301
 302                 /* Perform translation (see comment above) */
 303                 if ((pfn >= backup_start) && (pfn < backup_end)) {
 304                         if (clear_user(buf, csize)) {
 305                                 read = -EFAULT;
 306                                 goto done;
 307                         }
 308
 309                         goto copy_done;
 310                 } else if (pfn < (CRASH_RELOCATE_SIZE / PAGE_SIZE))
 311                         pfn += relocate_start;
 312
 313                 if (pfn > saved_max_pfn) {
 314                         read = 0;
 315                         goto done;
 316                 }
 317
 318                 if (copy_oldmem_page(pfn, buf, csize, 1)) {
 319                         read = -EFAULT;
 320                         goto done;
 321                 }
 322
 323 copy_done:
 324                 buf += csize;
 325                 *ppos += csize;
 326                 read += csize;
 327                 count -= csize;
 328         }
 329 done:
 330         return read;
 331 }
 332 #endif
 333
 334 extern long vread(char *buf, char *addr, unsigned long count);
 335 extern long vwrite(char *buf, char *addr, unsigned long count);
 336
 337 /*
 338  * This function reads the *virtual* memory as seen by the kernel.
 339  */
 340 static ssize_t read_kmem(struct file *file, char __user *buf,
 341                          size_t count, loff_t *ppos)
 342 {
 343         unsigned long p = *ppos;
 344         ssize_t low_count, read, sz;
 345         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 346
 347         read = 0;
 348         if (p < (unsigned long) high_memory) {
 349                 low_count = count;
 350                 if (count > (unsigned long) high_memory - p)
 351                         low_count = (unsigned long) high_memory - p;
 352
 353 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 354                 /* we don't have page 0 mapped on sparc and m68k.. */
 355                 if (p < PAGE_SIZE && low_count > 0) {
 356                         size_t tmp = PAGE_SIZE - p;
 357                         if (tmp > low_count) tmp = low_count;
 358                         if (clear_user(buf, tmp))
 359                                 return -EFAULT;
 360                         buf += tmp;
 361                         p += tmp;
 362                         read += tmp;
 363                         low_count -= tmp;
 364                         count -= tmp;
 365                 }
 366 #endif
 367                 while (low_count > 0) {
 368                         /*
 369                          * Handle first page in case it's not aligned
 370                          */
 371                         if (-p & (PAGE_SIZE - 1))
 372                                 sz = -p & (PAGE_SIZE - 1);
 373                         else
 374                                 sz = PAGE_SIZE;
 375
 376                         sz = min_t(unsigned long, sz, low_count);
 377
 378                         /*
 379                          * On ia64 if a page has been mapped somewhere as
 380                          * uncached, then it must also be accessed uncached
 381                          * by the kernel or data corruption may occur
 382                          */
 383                         kbuf = xlate_dev_kmem_ptr((char *)p);
 384
 385                         if (copy_to_user(buf, kbuf, sz))
 386                                 return -EFAULT;
 387                         buf += sz;
 388                         p += sz;
 389                         read += sz;
 390                         low_count -= sz;
 391                         count -= sz;
 392                 }
 393         }
 394
 395         if (count > 0) {
 396                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 397                 if (!kbuf)
 398                         return -ENOMEM;
 399                 while (count > 0) {
 400                         int len = count;
 401
 402                         if (len > PAGE_SIZE)
 403                                 len = PAGE_SIZE;
 404                         len = vread(kbuf, (char *)p, len);
 405                         if (!len)
 406                                 break;
 407                         if (copy_to_user(buf, kbuf, len)) {
 408                                 free_page((unsigned long)kbuf);
 409                                 return -EFAULT;
 410                         }
 411                         count -= len;
 412                         buf += len;
 413                         read += len;
 414                         p += len;
 415                 }
 416                 free_page((unsigned long)kbuf);
 417         }
 418         *ppos = p;
 419         return read;
 420 }
 421
 422
 423 static inline ssize_t
 424 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
 425               size_t count, loff_t *ppos)
 426 {
 427         ssize_t written, sz;
 428         unsigned long copied;
 429
 430         written = 0;
 431 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 432         /* we don't have page 0 mapped on sparc and m68k.. */
 433         if (realp < PAGE_SIZE) {
 434                 unsigned long sz = PAGE_SIZE - realp;
 435                 if (sz > count)
 436                         sz = count;
 437                 /* Hmm. Do something? */
 438                 buf += sz;
 439                 p += sz;
 440                 realp += sz;
 441                 count -= sz;
 442                 written += sz;
 443         }
 444 #endif
 445
 446         while (count > 0) {
 447                 char *ptr;
 448                 /*
 449                  * Handle first page in case it's not aligned
 450                  */
 451                 if (-realp & (PAGE_SIZE - 1))
 452                         sz = -realp & (PAGE_SIZE - 1);
 453                 else
 454                         sz = PAGE_SIZE;
 455
 456                 sz = min_t(unsigned long, sz, count);
 457
 458                 /*
 459                  * On ia64 if a page has been mapped somewhere as
 460                  * uncached, then it must also be accessed uncached
 461                  * by the kernel or data corruption may occur
 462                  */
 463                 ptr = xlate_dev_kmem_ptr(p);
 464
 465                 copied = copy_from_user(ptr, buf, sz);
 466                 if (copied) {
 467                         ssize_t ret;
 468
 469                         ret = written + (sz - copied);
 470                         if (ret)
 471                                 return ret;
 472                         return -EFAULT;
 473                 }
 474                 buf += sz;
 475                 p += sz;
 476                 realp += sz;
 477                 count -= sz;
 478                 written += sz;
 479         }
 480
 481         *ppos += written;
 482         return written;
 483 }
 484
 485
 486 /*
 487  * This function writes to the *virtual* memory as seen by the kernel.
 488  */
 489 static ssize_t write_kmem(struct file * file, const char __user * buf,
 490                           size_t count, loff_t *ppos)
 491 {
 492         unsigned long p = *ppos;
 493         ssize_t wrote = 0;
 494         ssize_t virtr = 0;
 495         ssize_t written;
 496         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 497
 498         if (p < (unsigned long) high_memory) {
 499
 500                 wrote = count;
 501                 if (count > (unsigned long) high_memory - p)
 502                         wrote = (unsigned long) high_memory - p;
 503
 504                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
 505                 if (written != wrote)
 506                         return written;
 507                 wrote = written;
 508                 p += wrote;
 509                 buf += wrote;
 510                 count -= wrote;
 511         }
 512
 513         if (count > 0) {
 514                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 515                 if (!kbuf)
 516                         return wrote ? wrote : -ENOMEM;
 517                 while (count > 0) {
 518                         int len = count;
 519
 520                         if (len > PAGE_SIZE)
 521                                 len = PAGE_SIZE;
 522                         if (len) {
 523                                 written = copy_from_user(kbuf, buf, len);
 524                                 if (written) {
 525                                         ssize_t ret;
 526
 527                                         free_page((unsigned long)kbuf);
 528                                         ret = wrote + virtr + (len - written);
 529                                         return ret ? ret : -EFAULT;
 530                                 }
 531                         }
 532                         len = vwrite(kbuf, (char *)p, len);
 533                         count -= len;
 534                         buf += len;
 535                         virtr += len;
 536                         p += len;
 537                 }
 538                 free_page((unsigned long)kbuf);
 539         }
 540
 541         *ppos = p;
 542         return virtr + wrote;
 543 }
 544
 545 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
 546 static ssize_t read_port(struct file * file, char __user * buf,
 547                          size_t count, loff_t *ppos)
 548 {
 549         unsigned long i = *ppos;
 550         char __user *tmp = buf;
 551
 552         if (!access_ok(VERIFY_WRITE, buf, count))
 553                 return -EFAULT;
 554         while (count-- > 0 && i < 65536) {
 555                 if (__put_user(inb(i),tmp) < 0)
 556                         return -EFAULT;
 557                 i++;
 558                 tmp++;
 559         }
 560         *ppos = i;
 561         return tmp-buf;
 562 }
 563
 564 static ssize_t write_port(struct file * file, const char __user * buf,
 565                           size_t count, loff_t *ppos)
 566 {
 567         unsigned long i = *ppos;
 568         const char __user * tmp = buf;
 569
 570         if (!access_ok(VERIFY_READ,buf,count))
 571                 return -EFAULT;
 572         while (count-- > 0 && i < 65536) {
 573                 char c;
 574                 if (__get_user(c, tmp))
 575                         return -EFAULT;
 576                 outb(c,i);
 577                 i++;
 578                 tmp++;
 579         }
 580         *ppos = i;
 581         return tmp-buf;
 582 }
 583 #endif
 584
 585 static ssize_t read_null(struct file * file, char __user * buf,
 586                          size_t count, loff_t *ppos)
 587 {
 588         return 0;
 589 }
 590
 591 static ssize_t write_null(struct file * file, const char __user * buf,
 592                           size_t count, loff_t *ppos)
 593 {
 594         return count;
 595 }
 596
 597 #ifdef CONFIG_MMU
 598 /*
 599  * For fun, we are using the MMU for this.
 600  */
 601 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
 602 {
 603         struct mm_struct *mm;
 604         struct vm_area_struct * vma;
 605         unsigned long addr=(unsigned long)buf;
 606
 607         mm = current->mm;
 608         /* Oops, this was forgotten before. -ben */
 609         down_read(&mm->mmap_sem);
 610
 611         /* For private mappings, just map in zero pages. */
 612         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
 613                 unsigned long count;
 614
 615                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
 616                         goto out_up;
 617                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
 618                         break;
 619                 count = vma->vm_end - addr;
 620                 if (count > size)
 621                         count = size;
 622
 623                 zap_page_range(vma, addr, count, NULL);
 624                 zeromap_page_range(vma, addr, count, PAGE_COPY);
 625
 626                 size -= count;
 627                 buf += count;
 628                 addr += count;
 629                 if (size == 0)
 630                         goto out_up;
 631         }
 632
 633         up_read(&mm->mmap_sem);
 634
 635         /* The shared case is hard. Let's do the conventional zeroing. */
 636         do {
 637                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
 638                 if (unwritten)
 639                         return size + unwritten - PAGE_SIZE;
 640                 cond_resched();
 641                 buf += PAGE_SIZE;
 642                 size -= PAGE_SIZE;
 643         } while (size);
 644
 645         return size;
 646 out_up:
 647         up_read(&mm->mmap_sem);
 648         return size;
 649 }
 650
 651 static ssize_t read_zero(struct file * file, char __user * buf,
 652                          size_t count, loff_t *ppos)
 653 {
 654         unsigned long left, unwritten, written = 0;
 655
 656         if (!count)
 657                 return 0;
 658
 659         if (!access_ok(VERIFY_WRITE, buf, count))
 660                 return -EFAULT;
 661
 662         left = count;
 663
 664         /* do we want to be clever? Arbitrary cut-off */
 665         if (count >= PAGE_SIZE*4) {
 666                 unsigned long partial;
 667
 668                 /* How much left of the page? */
 669                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
 670                 unwritten = clear_user(buf, partial);
 671                 written = partial - unwritten;
 672                 if (unwritten)
 673                         goto out;
 674                 left -= partial;
 675                 buf += partial;
 676                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
 677                 written += (left & PAGE_MASK) - unwritten;
 678                 if (unwritten)
 679                         goto out;
 680                 buf += left & PAGE_MASK;
 681                 left &= ~PAGE_MASK;
 682         }
 683         unwritten = clear_user(buf, left);
 684         written += left - unwritten;
 685 out:
 686         return written ? written : -EFAULT;
 687 }
 688
 689 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 690 {
 691         if (vma->vm_flags & VM_SHARED)
 692                 return shmem_zero_setup(vma);
 693         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
 694                 return -EAGAIN;
 695         return 0;
 696 }
 697 #else /* CONFIG_MMU */
 698 static ssize_t read_zero(struct file * file, char * buf,
 699                          size_t count, loff_t *ppos)
 700 {
 701         size_t todo = count;
 702
 703         while (todo) {
 704                 size_t chunk = todo;
 705
 706                 if (chunk > 4096)
 707                         chunk = 4096;   /* Just for latency reasons */
 708                 if (clear_user(buf, chunk))
 709                         return -EFAULT;
 710                 buf += chunk;
 711                 todo -= chunk;
 712                 cond_resched();
 713         }
 714         return count;
 715 }
 716
 717 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
 718 {
 719         return -ENOSYS;
 720 }
 721 #endif /* CONFIG_MMU */
 722
 723 static ssize_t write_full(struct file * file, const char __user * buf,
 724                           size_t count, loff_t *ppos)
 725 {
 726         return -ENOSPC;
 727 }
 728
 729 /*
 730  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 731  * can fopen() both devices with "a" now.  This was previously impossible.
 732  * -- SRB.
 733  */
 734
 735 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
 736 {
 737         return file->f_pos = 0;
 738 }
 739
 740 /*
 741  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 742  * check against negative addresses: they are ok. The return value is weird,
 743  * though, in that case (0).
 744  *
 745  * also note that seeking relative to the "end of file" isn't supported:
 746  * it has no meaning, so it returns -EINVAL.
 747  */
 748 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
 749 {
 750         loff_t ret;
 751
 752         down(&file->f_dentry->d_inode->i_sem);
 753         switch (orig) {
 754                 case 0:
 755                         file->f_pos = offset;
 756                         ret = file->f_pos;
 757                         force_successful_syscall_return();
 758                         break;
 759                 case 1:
 760                         file->f_pos += offset;
 761                         ret = file->f_pos;
 762                         force_successful_syscall_return();
 763                         break;
 764                 default:
 765                         ret = -EINVAL;
 766         }
 767         up(&file->f_dentry->d_inode->i_sem);
 768         return ret;
 769 }
 770
 771 static int open_port(struct inode * inode, struct file * filp)
 772 {
 773         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 774 }
 775
 776 #define zero_lseek      null_lseek
 777 #define full_lseek      null_lseek
 778 #define write_zero      write_null
 779 #define read_full       read_zero
 780 #define open_mem        open_port
 781 #define open_kmem       open_mem
 782 #define open_oldmem     open_mem
 783
 784 static struct file_operations mem_fops = {
 785         .llseek         = memory_lseek,
 786         .read           = read_mem,
 787         .write          = write_mem,
 788         .mmap           = mmap_mem,
 789         .open           = open_mem,
 790 };
 791
 792 static struct file_operations kmem_fops = {
 793         .llseek         = memory_lseek,
 794         .read           = read_kmem,
 795         .write          = write_kmem,
 796         .mmap           = mmap_kmem,
 797         .open           = open_kmem,
 798 };
 799
 800 static struct file_operations null_fops = {
 801         .llseek         = null_lseek,
 802         .read           = read_null,
 803         .write          = write_null,
 804 };
 805
 806 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
 807 static struct file_operations port_fops = {
 808         .llseek         = memory_lseek,
 809         .read           = read_port,
 810         .write          = write_port,
 811         .open           = open_port,
 812 };
 813 #endif
 814
 815 static struct file_operations zero_fops = {
 816         .llseek         = zero_lseek,
 817         .read           = read_zero,
 818         .write          = write_zero,
 819         .mmap           = mmap_zero,
 820 };
 821
 822 static struct backing_dev_info zero_bdi = {
 823         .capabilities   = BDI_CAP_MAP_COPY,
 824 };
 825
 826 static struct file_operations full_fops = {
 827         .llseek         = full_lseek,
 828         .read           = read_full,
 829         .write          = write_full,
 830 };
 831
 832 #ifdef CONFIG_CRASH_DUMP
 833 static struct file_operations oldmem_fops = {
 834         .read   = read_oldmem,
 835         .open   = open_oldmem,
 836 };
 837 #endif
 838
 839 static ssize_t kmsg_write(struct file * file, const char __user * buf,
 840                           size_t count, loff_t *ppos)
 841 {
 842         char *tmp;
 843         int ret;
 844
 845         tmp = kmalloc(count + 1, GFP_KERNEL);
 846         if (tmp == NULL)
 847                 return -ENOMEM;
 848         ret = -EFAULT;
 849         if (!copy_from_user(tmp, buf, count)) {
 850                 tmp[count] = 0;
 851                 ret = printk("%s", tmp);
 852         }
 853         kfree(tmp);
 854         return ret;
 855 }
 856
 857 static struct file_operations kmsg_fops = {
 858         .write =        kmsg_write,
 859 };
 860
 861 static int memory_open(struct inode * inode, struct file * filp)
 862 {
 863         switch (iminor(inode)) {
 864                 case 1:
 865                         filp->f_op = &mem_fops;
 866                         break;
 867                 case 2:
 868                         filp->f_op = &kmem_fops;
 869                         break;
 870                 case 3:
 871                         filp->f_op = &null_fops;
 872                         break;
 873 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
 874                 case 4:
 875                         filp->f_op = &port_fops;
 876                         break;
 877 #endif
 878                 case 5:
 879                         filp->f_mapping->backing_dev_info = &zero_bdi;
 880                         filp->f_op = &zero_fops;
 881                         break;
 882                 case 7:
 883                         filp->f_op = &full_fops;
 884                         break;
 885                 case 8:
 886                         filp->f_op = &random_fops;
 887                         break;
 888                 case 9:
 889                         filp->f_op = &urandom_fops;
 890                         break;
 891                 case 11:
 892                         filp->f_op = &kmsg_fops;
 893                         break;
 894 #ifdef CONFIG_CRASH_DUMP
 895                 case 12:
 896                         filp->f_op = &oldmem_fops;
 897                         break;
 898 #endif
 899                 default:
 900                         return -ENXIO;
 901         }
 902         if (filp->f_op && filp->f_op->open)
 903                 return filp->f_op->open(inode,filp);
 904         return 0;
 905 }
 906
 907 static struct file_operations memory_fops = {
 908         .open           = memory_open,  /* just a selector for the real open */
 909 };
 910
 911 static const struct {
 912         unsigned int            minor;
 913         char                    *name;
 914         umode_t                 mode;
 915         struct file_operations  *fops;
 916 } devlist[] = { /* list of minor devices */
 917         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
 918         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
 919         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
 920 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
 921         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
 922 #endif
 923         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
 924         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
 925         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
 926         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
 927         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
 928 #ifdef CONFIG_CRASH_DUMP
 929         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
 930 #endif
 931 };
 932
 933 static struct class *mem_class;
 934
 935 static int __init chr_dev_init(void)
 936 {
 937         int i;
 938
 939         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 940                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 941
 942         mem_class = class_create(THIS_MODULE, "mem");
 943         for (i = 0; i < ARRAY_SIZE(devlist); i++) {
 944                 class_device_create(mem_class, MKDEV(MEM_MAJOR, devlist[i].minor),
 945                                         NULL, devlist[i].name);
 946                 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
 947                                 S_IFCHR | devlist[i].mode, devlist[i].name);
 948         }
 949
 950         return 0;
 951 }
 952
 953 fs_initcall(chr_dev_init);