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/backing-dev.h>
  25 #include <linux/splice.h>
  26 #include <linux/pfn.h>
  27 #include <linux/export.h>
  28 #include <linux/io.h>
  29 #include <linux/uio.h>
  30
  31 #include <linux/uaccess.h>
  32
  33 #ifdef CONFIG_IA64
  34 # include <linux/efi.h>
  35 #endif
  36
  37 #define DEVPORT_MINOR   4
  38
  39 static inline unsigned long size_inside_page(unsigned long start,
  40                                              unsigned long size)
  41 {
  42         unsigned long sz;
  43
  44         sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
  45
  46         return min(sz, size);
  47 }
  48
  49 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  50 static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
  51 {
  52         return addr + count <= __pa(high_memory);
  53 }
  54
  55 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
  56 {
  57         return 1;
  58 }
  59 #endif
  60
  61 #ifdef CONFIG_STRICT_DEVMEM
  62 static inline int page_is_allowed(unsigned long pfn)
  63 {
  64         return devmem_is_allowed(pfn);
  65 }
  66 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  67 {
  68         u64 from = ((u64)pfn) << PAGE_SHIFT;
  69         u64 to = from + size;
  70         u64 cursor = from;
  71
  72         while (cursor < to) {
  73                 if (!devmem_is_allowed(pfn))
  74                         return 0;
  75                 cursor += PAGE_SIZE;
  76                 pfn++;
  77         }
  78         return 1;
  79 }
  80 #else
  81 static inline int page_is_allowed(unsigned long pfn)
  82 {
  83         return 1;
  84 }
  85 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  86 {
  87         return 1;
  88 }
  89 #endif
  90
  91 #ifndef unxlate_dev_mem_ptr
  92 #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
  93 void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
  94 {
  95 }
  96 #endif
  97
  98 /*
  99  * This funcion reads the *physical* memory. The f_pos points directly to the
 100  * memory location.
 101  */
 102 static ssize_t read_mem(struct file *file, char __user *buf,
 103                         size_t count, loff_t *ppos)
 104 {
 105         phys_addr_t p = *ppos;
 106         ssize_t read, sz;
 107         void *ptr;
 108
 109         if (p != *ppos)
 110                 return 0;
 111
 112         if (!valid_phys_addr_range(p, count))
 113                 return -EFAULT;
 114         read = 0;
 115 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 116         /* we don't have page 0 mapped on sparc and m68k.. */
 117         if (p < PAGE_SIZE) {
 118                 sz = size_inside_page(p, count);
 119                 if (sz > 0) {
 120                         if (clear_user(buf, sz))
 121                                 return -EFAULT;
 122                         buf += sz;
 123                         p += sz;
 124                         count -= sz;
 125                         read += sz;
 126                 }
 127         }
 128 #endif
 129
 130         while (count > 0) {
 131                 unsigned long remaining;
 132                 int allowed;
 133
 134                 sz = size_inside_page(p, count);
 135
 136                 allowed = page_is_allowed(p >> PAGE_SHIFT);
 137                 if (!allowed)
 138                         return -EPERM;
 139                 if (allowed == 2) {
 140                         /* Show zeros for restricted memory. */
 141                         remaining = clear_user(buf, sz);
 142                 } else {
 143                         /*
 144                          * On ia64 if a page has been mapped somewhere as
 145                          * uncached, then it must also be accessed uncached
 146                          * by the kernel or data corruption may occur.
 147                          */
 148                         ptr = xlate_dev_mem_ptr(p);
 149                         if (!ptr)
 150                                 return -EFAULT;
 151
 152                         remaining = copy_to_user(buf, ptr, sz);
 153
 154                         unxlate_dev_mem_ptr(p, ptr);
 155                 }
 156
 157                 if (remaining)
 158                         return -EFAULT;
 159
 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         phys_addr_t p = *ppos;
 174         ssize_t written, sz;
 175         unsigned long copied;
 176         void *ptr;
 177
 178         if (p != *ppos)
 179                 return -EFBIG;
 180
 181         if (!valid_phys_addr_range(p, count))
 182                 return -EFAULT;
 183
 184         written = 0;
 185
 186 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 187         /* we don't have page 0 mapped on sparc and m68k.. */
 188         if (p < PAGE_SIZE) {
 189                 sz = size_inside_page(p, count);
 190                 /* Hmm. Do something? */
 191                 buf += sz;
 192                 p += sz;
 193                 count -= sz;
 194                 written += sz;
 195         }
 196 #endif
 197
 198         while (count > 0) {
 199                 int allowed;
 200
 201                 sz = size_inside_page(p, count);
 202
 203                 allowed = page_is_allowed(p >> PAGE_SHIFT);
 204                 if (!allowed)
 205                         return -EPERM;
 206
 207                 /* Skip actual writing when a page is marked as restricted. */
 208                 if (allowed == 1) {
 209                         /*
 210                          * On ia64 if a page has been mapped somewhere as
 211                          * uncached, then it must also be accessed uncached
 212                          * by the kernel or data corruption may occur.
 213                          */
 214                         ptr = xlate_dev_mem_ptr(p);
 215                         if (!ptr) {
 216                                 if (written)
 217                                         break;
 218                                 return -EFAULT;
 219                         }
 220
 221                         copied = copy_from_user(ptr, buf, sz);
 222                         unxlate_dev_mem_ptr(p, ptr);
 223                         if (copied) {
 224                                 written += sz - copied;
 225                                 if (written)
 226                                         break;
 227                                 return -EFAULT;
 228                         }
 229                 }
 230
 231                 buf += sz;
 232                 p += sz;
 233                 count -= sz;
 234                 written += sz;
 235         }
 236
 237         *ppos += written;
 238         return written;
 239 }
 240
 241 int __weak phys_mem_access_prot_allowed(struct file *file,
 242         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
 243 {
 244         return 1;
 245 }
 246
 247 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 248
 249 /*
 250  * Architectures vary in how they handle caching for addresses
 251  * outside of main memory.
 252  *
 253  */
 254 #ifdef pgprot_noncached
 255 static int uncached_access(struct file *file, phys_addr_t addr)
 256 {
 257 #if defined(CONFIG_IA64)
 258         /*
 259          * On ia64, we ignore O_DSYNC because we cannot tolerate memory
 260          * attribute aliases.
 261          */
 262         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
 263 #elif defined(CONFIG_MIPS)
 264         {
 265                 extern int __uncached_access(struct file *file,
 266                                              unsigned long addr);
 267
 268                 return __uncached_access(file, addr);
 269         }
 270 #else
 271         /*
 272          * Accessing memory above the top the kernel knows about or through a
 273          * file pointer
 274          * that was marked O_DSYNC will be done non-cached.
 275          */
 276         if (file->f_flags & O_DSYNC)
 277                 return 1;
 278         return addr >= __pa(high_memory);
 279 #endif
 280 }
 281 #endif
 282
 283 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 284                                      unsigned long size, pgprot_t vma_prot)
 285 {
 286 #ifdef pgprot_noncached
 287         phys_addr_t offset = pfn << PAGE_SHIFT;
 288
 289         if (uncached_access(file, offset))
 290                 return pgprot_noncached(vma_prot);
 291 #endif
 292         return vma_prot;
 293 }
 294 #endif
 295
 296 #ifndef CONFIG_MMU
 297 static unsigned long get_unmapped_area_mem(struct file *file,
 298                                            unsigned long addr,
 299                                            unsigned long len,
 300                                            unsigned long pgoff,
 301                                            unsigned long flags)
 302 {
 303         if (!valid_mmap_phys_addr_range(pgoff, len))
 304                 return (unsigned long) -EINVAL;
 305         return pgoff << PAGE_SHIFT;
 306 }
 307
 308 /* permit direct mmap, for read, write or exec */
 309 static unsigned memory_mmap_capabilities(struct file *file)
 310 {
 311         return NOMMU_MAP_DIRECT |
 312                 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
 313 }
 314
 315 static unsigned zero_mmap_capabilities(struct file *file)
 316 {
 317         return NOMMU_MAP_COPY;
 318 }
 319
 320 /* can't do an in-place private mapping if there's no MMU */
 321 static inline int private_mapping_ok(struct vm_area_struct *vma)
 322 {
 323         return vma->vm_flags & VM_MAYSHARE;
 324 }
 325 #else
 326
 327 static inline int private_mapping_ok(struct vm_area_struct *vma)
 328 {
 329         return 1;
 330 }
 331 #endif
 332
 333 static const struct vm_operations_struct mmap_mem_ops = {
 334 #ifdef CONFIG_HAVE_IOREMAP_PROT
 335         .access = generic_access_phys
 336 #endif
 337 };
 338
 339 static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 340 {
 341         size_t size = vma->vm_end - vma->vm_start;
 342         phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
 343
 344         /* It's illegal to wrap around the end of the physical address space. */
 345         if (offset + (phys_addr_t)size - 1 < offset)
 346                 return -EINVAL;
 347
 348         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
 349                 return -EINVAL;
 350
 351         if (!private_mapping_ok(vma))
 352                 return -ENOSYS;
 353
 354         if (!range_is_allowed(vma->vm_pgoff, size))
 355                 return -EPERM;
 356
 357         if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
 358                                                 &vma->vm_page_prot))
 359                 return -EINVAL;
 360
 361         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 362                                                  size,
 363                                                  vma->vm_page_prot);
 364
 365         vma->vm_ops = &mmap_mem_ops;
 366
 367         /* Remap-pfn-range will mark the range VM_IO */
 368         if (remap_pfn_range(vma,
 369                             vma->vm_start,
 370                             vma->vm_pgoff,
 371                             size,
 372                             vma->vm_page_prot)) {
 373                 return -EAGAIN;
 374         }
 375         return 0;
 376 }
 377
 378 static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 379 {
 380         unsigned long pfn;
 381
 382         /* Turn a kernel-virtual address into a physical page frame */
 383         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 384
 385         /*
 386          * RED-PEN: on some architectures there is more mapped memory than
 387          * available in mem_map which pfn_valid checks for. Perhaps should add a
 388          * new macro here.
 389          *
 390          * RED-PEN: vmalloc is not supported right now.
 391          */
 392         if (!pfn_valid(pfn))
 393                 return -EIO;
 394
 395         vma->vm_pgoff = pfn;
 396         return mmap_mem(file, vma);
 397 }
 398
 399 /*
 400  * This function reads the *virtual* memory as seen by the kernel.
 401  */
 402 static ssize_t read_kmem(struct file *file, char __user *buf,
 403                          size_t count, loff_t *ppos)
 404 {
 405         unsigned long p = *ppos;
 406         ssize_t low_count, read, sz;
 407         char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 408         int err = 0;
 409
 410         read = 0;
 411         if (p < (unsigned long) high_memory) {
 412                 low_count = count;
 413                 if (count > (unsigned long)high_memory - p)
 414                         low_count = (unsigned long)high_memory - p;
 415
 416 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 417                 /* we don't have page 0 mapped on sparc and m68k.. */
 418                 if (p < PAGE_SIZE && low_count > 0) {
 419                         sz = size_inside_page(p, low_count);
 420                         if (clear_user(buf, sz))
 421                                 return -EFAULT;
 422                         buf += sz;
 423                         p += sz;
 424                         read += sz;
 425                         low_count -= sz;
 426                         count -= sz;
 427                 }
 428 #endif
 429                 while (low_count > 0) {
 430                         sz = size_inside_page(p, low_count);
 431
 432                         /*
 433                          * On ia64 if a page has been mapped somewhere as
 434                          * uncached, then it must also be accessed uncached
 435                          * by the kernel or data corruption may occur
 436                          */
 437                         kbuf = xlate_dev_kmem_ptr((void *)p);
 438
 439                         if (copy_to_user(buf, kbuf, sz))
 440                                 return -EFAULT;
 441                         buf += sz;
 442                         p += sz;
 443                         read += sz;
 444                         low_count -= sz;
 445                         count -= sz;
 446                 }
 447         }
 448
 449         if (count > 0) {
 450                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 451                 if (!kbuf)
 452                         return -ENOMEM;
 453                 while (count > 0) {
 454                         sz = size_inside_page(p, count);
 455                         if (!is_vmalloc_or_module_addr((void *)p)) {
 456                                 err = -ENXIO;
 457                                 break;
 458                         }
 459                         sz = vread(kbuf, (char *)p, sz);
 460                         if (!sz)
 461                                 break;
 462                         if (copy_to_user(buf, kbuf, sz)) {
 463                                 err = -EFAULT;
 464                                 break;
 465                         }
 466                         count -= sz;
 467                         buf += sz;
 468                         read += sz;
 469                         p += sz;
 470                 }
 471                 free_page((unsigned long)kbuf);
 472         }
 473         *ppos = p;
 474         return read ? read : err;
 475 }
 476
 477
 478 static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
 479                                 size_t count, loff_t *ppos)
 480 {
 481         ssize_t written, sz;
 482         unsigned long copied;
 483
 484         written = 0;
 485 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 486         /* we don't have page 0 mapped on sparc and m68k.. */
 487         if (p < PAGE_SIZE) {
 488                 sz = size_inside_page(p, count);
 489                 /* Hmm. Do something? */
 490                 buf += sz;
 491                 p += sz;
 492                 count -= sz;
 493                 written += sz;
 494         }
 495 #endif
 496
 497         while (count > 0) {
 498                 void *ptr;
 499
 500                 sz = size_inside_page(p, count);
 501
 502                 /*
 503                  * On ia64 if a page has been mapped somewhere as uncached, then
 504                  * it must also be accessed uncached by the kernel or data
 505                  * corruption may occur.
 506                  */
 507                 ptr = xlate_dev_kmem_ptr((void *)p);
 508
 509                 copied = copy_from_user(ptr, buf, sz);
 510                 if (copied) {
 511                         written += sz - copied;
 512                         if (written)
 513                                 break;
 514                         return -EFAULT;
 515                 }
 516                 buf += sz;
 517                 p += sz;
 518                 count -= sz;
 519                 written += sz;
 520         }
 521
 522         *ppos += written;
 523         return written;
 524 }
 525
 526 /*
 527  * This function writes to the *virtual* memory as seen by the kernel.
 528  */
 529 static ssize_t write_kmem(struct file *file, const char __user *buf,
 530                           size_t count, loff_t *ppos)
 531 {
 532         unsigned long p = *ppos;
 533         ssize_t wrote = 0;
 534         ssize_t virtr = 0;
 535         char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 536         int err = 0;
 537
 538         if (p < (unsigned long) high_memory) {
 539                 unsigned long to_write = min_t(unsigned long, count,
 540                                                (unsigned long)high_memory - p);
 541                 wrote = do_write_kmem(p, buf, to_write, ppos);
 542                 if (wrote != to_write)
 543                         return wrote;
 544                 p += wrote;
 545                 buf += wrote;
 546                 count -= wrote;
 547         }
 548
 549         if (count > 0) {
 550                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 551                 if (!kbuf)
 552                         return wrote ? wrote : -ENOMEM;
 553                 while (count > 0) {
 554                         unsigned long sz = size_inside_page(p, count);
 555                         unsigned long n;
 556
 557                         if (!is_vmalloc_or_module_addr((void *)p)) {
 558                                 err = -ENXIO;
 559                                 break;
 560                         }
 561                         n = copy_from_user(kbuf, buf, sz);
 562                         if (n) {
 563                                 err = -EFAULT;
 564                                 break;
 565                         }
 566                         vwrite(kbuf, (char *)p, sz);
 567                         count -= sz;
 568                         buf += sz;
 569                         virtr += sz;
 570                         p += sz;
 571                 }
 572                 free_page((unsigned long)kbuf);
 573         }
 574
 575         *ppos = p;
 576         return virtr + wrote ? : err;
 577 }
 578
 579 static ssize_t read_port(struct file *file, char __user *buf,
 580                          size_t count, loff_t *ppos)
 581 {
 582         unsigned long i = *ppos;
 583         char __user *tmp = buf;
 584
 585         if (!access_ok(VERIFY_WRITE, buf, count))
 586                 return -EFAULT;
 587         while (count-- > 0 && i < 65536) {
 588                 if (__put_user(inb(i), tmp) < 0)
 589                         return -EFAULT;
 590                 i++;
 591                 tmp++;
 592         }
 593         *ppos = i;
 594         return tmp-buf;
 595 }
 596
 597 static ssize_t write_port(struct file *file, const char __user *buf,
 598                           size_t count, loff_t *ppos)
 599 {
 600         unsigned long i = *ppos;
 601         const char __user *tmp = buf;
 602
 603         if (!access_ok(VERIFY_READ, buf, count))
 604                 return -EFAULT;
 605         while (count-- > 0 && i < 65536) {
 606                 char c;
 607
 608                 if (__get_user(c, tmp)) {
 609                         if (tmp > buf)
 610                                 break;
 611                         return -EFAULT;
 612                 }
 613                 outb(c, i);
 614                 i++;
 615                 tmp++;
 616         }
 617         *ppos = i;
 618         return tmp-buf;
 619 }
 620
 621 static ssize_t read_null(struct file *file, char __user *buf,
 622                          size_t count, loff_t *ppos)
 623 {
 624         return 0;
 625 }
 626
 627 static ssize_t write_null(struct file *file, const char __user *buf,
 628                           size_t count, loff_t *ppos)
 629 {
 630         return count;
 631 }
 632
 633 static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
 634 {
 635         return 0;
 636 }
 637
 638 static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
 639 {
 640         size_t count = iov_iter_count(from);
 641         iov_iter_advance(from, count);
 642         return count;
 643 }
 644
 645 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 646                         struct splice_desc *sd)
 647 {
 648         return sd->len;
 649 }
 650
 651 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
 652                                  loff_t *ppos, size_t len, unsigned int flags)
 653 {
 654         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 655 }
 656
 657 static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
 658 {
 659         size_t written = 0;
 660
 661         while (iov_iter_count(iter)) {
 662                 size_t chunk = iov_iter_count(iter), n;
 663
 664                 if (chunk > PAGE_SIZE)
 665                         chunk = PAGE_SIZE;      /* Just for latency reasons */
 666                 n = iov_iter_zero(chunk, iter);
 667                 if (!n && iov_iter_count(iter))
 668                         return written ? written : -EFAULT;
 669                 written += n;
 670                 if (signal_pending(current))
 671                         return written ? written : -ERESTARTSYS;
 672                 cond_resched();
 673         }
 674         return written;
 675 }
 676
 677 static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 678 {
 679 #ifndef CONFIG_MMU
 680         return -ENOSYS;
 681 #endif
 682         if (vma->vm_flags & VM_SHARED)
 683                 return shmem_zero_setup(vma);
 684         return 0;
 685 }
 686
 687 static ssize_t write_full(struct file *file, const char __user *buf,
 688                           size_t count, loff_t *ppos)
 689 {
 690         return -ENOSPC;
 691 }
 692
 693 /*
 694  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 695  * can fopen() both devices with "a" now.  This was previously impossible.
 696  * -- SRB.
 697  */
 698 static loff_t null_lseek(struct file *file, loff_t offset, int orig)
 699 {
 700         return file->f_pos = 0;
 701 }
 702
 703 /*
 704  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 705  * check against negative addresses: they are ok. The return value is weird,
 706  * though, in that case (0).
 707  *
 708  * also note that seeking relative to the "end of file" isn't supported:
 709  * it has no meaning, so it returns -EINVAL.
 710  */
 711 static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 712 {
 713         loff_t ret;
 714
 715         mutex_lock(&file_inode(file)->i_mutex);
 716         switch (orig) {
 717         case SEEK_CUR:
 718                 offset += file->f_pos;
 719         case SEEK_SET:
 720                 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
 721                 if (IS_ERR_VALUE((unsigned long long)offset)) {
 722                         ret = -EOVERFLOW;
 723                         break;
 724                 }
 725                 file->f_pos = offset;
 726                 ret = file->f_pos;
 727                 force_successful_syscall_return();
 728                 break;
 729         default:
 730                 ret = -EINVAL;
 731         }
 732         mutex_unlock(&file_inode(file)->i_mutex);
 733         return ret;
 734 }
 735
 736 static int open_port(struct inode *inode, struct file *filp)
 737 {
 738         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 739 }
 740
 741 #define zero_lseek      null_lseek
 742 #define full_lseek      null_lseek
 743 #define write_zero      write_null
 744 #define write_iter_zero write_iter_null
 745 #define open_mem        open_port
 746 #define open_kmem       open_mem
 747
 748 static const struct file_operations __maybe_unused mem_fops = {
 749         .llseek         = memory_lseek,
 750         .read           = read_mem,
 751         .write          = write_mem,
 752         .mmap           = mmap_mem,
 753         .open           = open_mem,
 754 #ifndef CONFIG_MMU
 755         .get_unmapped_area = get_unmapped_area_mem,
 756         .mmap_capabilities = memory_mmap_capabilities,
 757 #endif
 758 };
 759
 760 static const struct file_operations __maybe_unused kmem_fops = {
 761         .llseek         = memory_lseek,
 762         .read           = read_kmem,
 763         .write          = write_kmem,
 764         .mmap           = mmap_kmem,
 765         .open           = open_kmem,
 766 #ifndef CONFIG_MMU
 767         .get_unmapped_area = get_unmapped_area_mem,
 768         .mmap_capabilities = memory_mmap_capabilities,
 769 #endif
 770 };
 771
 772 static const struct file_operations null_fops = {
 773         .llseek         = null_lseek,
 774         .read           = read_null,
 775         .write          = write_null,
 776         .read_iter      = read_iter_null,
 777         .write_iter     = write_iter_null,
 778         .splice_write   = splice_write_null,
 779 };
 780
 781 static const struct file_operations __maybe_unused port_fops = {
 782         .llseek         = memory_lseek,
 783         .read           = read_port,
 784         .write          = write_port,
 785         .open           = open_port,
 786 };
 787
 788 static const struct file_operations zero_fops = {
 789         .llseek         = zero_lseek,
 790         .write          = write_zero,
 791         .read_iter      = read_iter_zero,
 792         .write_iter     = write_iter_zero,
 793         .mmap           = mmap_zero,
 794 #ifndef CONFIG_MMU
 795         .mmap_capabilities = zero_mmap_capabilities,
 796 #endif
 797 };
 798
 799 static const struct file_operations full_fops = {
 800         .llseek         = full_lseek,
 801         .read_iter      = read_iter_zero,
 802         .write          = write_full,
 803 };
 804
 805 static const struct memdev {
 806         const char *name;
 807         umode_t mode;
 808         const struct file_operations *fops;
 809         fmode_t fmode;
 810 } devlist[] = {
 811 #ifdef CONFIG_DEVMEM
 812          [1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
 813 #endif
 814 #ifdef CONFIG_DEVKMEM
 815          [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET },
 816 #endif
 817          [3] = { "null", 0666, &null_fops, 0 },
 818 #ifdef CONFIG_DEVPORT
 819          [4] = { "port", 0, &port_fops, 0 },
 820 #endif
 821          [5] = { "zero", 0666, &zero_fops, 0 },
 822          [7] = { "full", 0666, &full_fops, 0 },
 823          [8] = { "random", 0666, &random_fops, 0 },
 824          [9] = { "urandom", 0666, &urandom_fops, 0 },
 825 #ifdef CONFIG_PRINTK
 826         [11] = { "kmsg", 0644, &kmsg_fops, 0 },
 827 #endif
 828 };
 829
 830 static int memory_open(struct inode *inode, struct file *filp)
 831 {
 832         int minor;
 833         const struct memdev *dev;
 834
 835         minor = iminor(inode);
 836         if (minor >= ARRAY_SIZE(devlist))
 837                 return -ENXIO;
 838
 839         dev = &devlist[minor];
 840         if (!dev->fops)
 841                 return -ENXIO;
 842
 843         filp->f_op = dev->fops;
 844         filp->f_mode |= dev->fmode;
 845
 846         if (dev->fops->open)
 847                 return dev->fops->open(inode, filp);
 848
 849         return 0;
 850 }
 851
 852 static const struct file_operations memory_fops = {
 853         .open = memory_open,
 854         .llseek = noop_llseek,
 855 };
 856
 857 static char *mem_devnode(struct device *dev, umode_t *mode)
 858 {
 859         if (mode && devlist[MINOR(dev->devt)].mode)
 860                 *mode = devlist[MINOR(dev->devt)].mode;
 861         return NULL;
 862 }
 863
 864 static struct class *mem_class;
 865
 866 static int __init chr_dev_init(void)
 867 {
 868         int minor;
 869
 870         if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
 871                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 872
 873         mem_class = class_create(THIS_MODULE, "mem");
 874         if (IS_ERR(mem_class))
 875                 return PTR_ERR(mem_class);
 876
 877         mem_class->devnode = mem_devnode;
 878         for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
 879                 if (!devlist[minor].name)
 880                         continue;
 881
 882                 /*
 883                  * Create /dev/port?
 884                  */
 885                 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
 886                         continue;
 887
 888                 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
 889                               NULL, devlist[minor].name);
 890         }
 891
 892         return tty_init();
 893 }
 894
 895 fs_initcall(chr_dev_init);