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 range_is_allowed(unsigned long pfn, unsigned long size)
  63 {
  64         u64 from = ((u64)pfn) << PAGE_SHIFT;
  65         u64 to = from + size;
  66         u64 cursor = from;
  67
  68         while (cursor < to) {
  69                 if (!devmem_is_allowed(pfn))
  70                         return 0;
  71                 cursor += PAGE_SIZE;
  72                 pfn++;
  73         }
  74         return 1;
  75 }
  76 #else
  77 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  78 {
  79         return 1;
  80 }
  81 #endif
  82
  83 #ifndef unxlate_dev_mem_ptr
  84 #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
  85 void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
  86 {
  87 }
  88 #endif
  89
  90 /*
  91  * This funcion reads the *physical* memory. The f_pos points directly to the
  92  * memory location.
  93  */
  94 static ssize_t read_mem(struct file *file, char __user *buf,
  95                         size_t count, loff_t *ppos)
  96 {
  97         phys_addr_t p = *ppos;
  98         ssize_t read, sz;
  99         void *ptr;
 100
 101         if (p != *ppos)
 102                 return 0;
 103
 104         if (!valid_phys_addr_range(p, count))
 105                 return -EFAULT;
 106         read = 0;
 107 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 108         /* we don't have page 0 mapped on sparc and m68k.. */
 109         if (p < PAGE_SIZE) {
 110                 sz = size_inside_page(p, count);
 111                 if (sz > 0) {
 112                         if (clear_user(buf, sz))
 113                                 return -EFAULT;
 114                         buf += sz;
 115                         p += sz;
 116                         count -= sz;
 117                         read += sz;
 118                 }
 119         }
 120 #endif
 121
 122         while (count > 0) {
 123                 unsigned long remaining;
 124
 125                 sz = size_inside_page(p, count);
 126
 127                 if (!range_is_allowed(p >> PAGE_SHIFT, count))
 128                         return -EPERM;
 129
 130                 /*
 131                  * On ia64 if a page has been mapped somewhere as uncached, then
 132                  * it must also be accessed uncached by the kernel or data
 133                  * corruption may occur.
 134                  */
 135                 ptr = xlate_dev_mem_ptr(p);
 136                 if (!ptr)
 137                         return -EFAULT;
 138
 139                 remaining = copy_to_user(buf, ptr, sz);
 140                 unxlate_dev_mem_ptr(p, ptr);
 141                 if (remaining)
 142                         return -EFAULT;
 143
 144                 buf += sz;
 145                 p += sz;
 146                 count -= sz;
 147                 read += sz;
 148         }
 149
 150         *ppos += read;
 151         return read;
 152 }
 153
 154 static ssize_t write_mem(struct file *file, const char __user *buf,
 155                          size_t count, loff_t *ppos)
 156 {
 157         phys_addr_t p = *ppos;
 158         ssize_t written, sz;
 159         unsigned long copied;
 160         void *ptr;
 161
 162         if (p != *ppos)
 163                 return -EFBIG;
 164
 165         if (!valid_phys_addr_range(p, count))
 166                 return -EFAULT;
 167
 168         written = 0;
 169
 170 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 171         /* we don't have page 0 mapped on sparc and m68k.. */
 172         if (p < PAGE_SIZE) {
 173                 sz = size_inside_page(p, count);
 174                 /* Hmm. Do something? */
 175                 buf += sz;
 176                 p += sz;
 177                 count -= sz;
 178                 written += sz;
 179         }
 180 #endif
 181
 182         while (count > 0) {
 183                 sz = size_inside_page(p, count);
 184
 185                 if (!range_is_allowed(p >> PAGE_SHIFT, sz))
 186                         return -EPERM;
 187
 188                 /*
 189                  * On ia64 if a page has been mapped somewhere as uncached, then
 190                  * it must also be accessed uncached by the kernel or data
 191                  * corruption may occur.
 192                  */
 193                 ptr = xlate_dev_mem_ptr(p);
 194                 if (!ptr) {
 195                         if (written)
 196                                 break;
 197                         return -EFAULT;
 198                 }
 199
 200                 copied = copy_from_user(ptr, buf, sz);
 201                 unxlate_dev_mem_ptr(p, ptr);
 202                 if (copied) {
 203                         written += sz - copied;
 204                         if (written)
 205                                 break;
 206                         return -EFAULT;
 207                 }
 208
 209                 buf += sz;
 210                 p += sz;
 211                 count -= sz;
 212                 written += sz;
 213         }
 214
 215         *ppos += written;
 216         return written;
 217 }
 218
 219 int __weak phys_mem_access_prot_allowed(struct file *file,
 220         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
 221 {
 222         return 1;
 223 }
 224
 225 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 226
 227 /*
 228  * Architectures vary in how they handle caching for addresses
 229  * outside of main memory.
 230  *
 231  */
 232 #ifdef pgprot_noncached
 233 static int uncached_access(struct file *file, phys_addr_t addr)
 234 {
 235 #if defined(CONFIG_IA64)
 236         /*
 237          * On ia64, we ignore O_DSYNC because we cannot tolerate memory
 238          * attribute aliases.
 239          */
 240         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
 241 #elif defined(CONFIG_MIPS)
 242         {
 243                 extern int __uncached_access(struct file *file,
 244                                              unsigned long addr);
 245
 246                 return __uncached_access(file, addr);
 247         }
 248 #else
 249         /*
 250          * Accessing memory above the top the kernel knows about or through a
 251          * file pointer
 252          * that was marked O_DSYNC will be done non-cached.
 253          */
 254         if (file->f_flags & O_DSYNC)
 255                 return 1;
 256         return addr >= __pa(high_memory);
 257 #endif
 258 }
 259 #endif
 260
 261 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 262                                      unsigned long size, pgprot_t vma_prot)
 263 {
 264 #ifdef pgprot_noncached
 265         phys_addr_t offset = pfn << PAGE_SHIFT;
 266
 267         if (uncached_access(file, offset))
 268                 return pgprot_noncached(vma_prot);
 269 #endif
 270         return vma_prot;
 271 }
 272 #endif
 273
 274 #ifndef CONFIG_MMU
 275 static unsigned long get_unmapped_area_mem(struct file *file,
 276                                            unsigned long addr,
 277                                            unsigned long len,
 278                                            unsigned long pgoff,
 279                                            unsigned long flags)
 280 {
 281         if (!valid_mmap_phys_addr_range(pgoff, len))
 282                 return (unsigned long) -EINVAL;
 283         return pgoff << PAGE_SHIFT;
 284 }
 285
 286 /* permit direct mmap, for read, write or exec */
 287 static unsigned memory_mmap_capabilities(struct file *file)
 288 {
 289         return NOMMU_MAP_DIRECT |
 290                 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
 291 }
 292
 293 static unsigned zero_mmap_capabilities(struct file *file)
 294 {
 295         return NOMMU_MAP_COPY;
 296 }
 297
 298 /* can't do an in-place private mapping if there's no MMU */
 299 static inline int private_mapping_ok(struct vm_area_struct *vma)
 300 {
 301         return vma->vm_flags & VM_MAYSHARE;
 302 }
 303 #else
 304
 305 static inline int private_mapping_ok(struct vm_area_struct *vma)
 306 {
 307         return 1;
 308 }
 309 #endif
 310
 311 static const struct vm_operations_struct mmap_mem_ops = {
 312 #ifdef CONFIG_HAVE_IOREMAP_PROT
 313         .access = generic_access_phys
 314 #endif
 315 };
 316
 317 static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 318 {
 319         size_t size = vma->vm_end - vma->vm_start;
 320
 321         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
 322                 return -EINVAL;
 323
 324         if (!private_mapping_ok(vma))
 325                 return -ENOSYS;
 326
 327         if (!range_is_allowed(vma->vm_pgoff, size))
 328                 return -EPERM;
 329
 330         if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
 331                                                 &vma->vm_page_prot))
 332                 return -EINVAL;
 333
 334         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 335                                                  size,
 336                                                  vma->vm_page_prot);
 337
 338         vma->vm_ops = &mmap_mem_ops;
 339
 340         /* Remap-pfn-range will mark the range VM_IO */
 341         if (remap_pfn_range(vma,
 342                             vma->vm_start,
 343                             vma->vm_pgoff,
 344                             size,
 345                             vma->vm_page_prot)) {
 346                 return -EAGAIN;
 347         }
 348         return 0;
 349 }
 350
 351 static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 352 {
 353         unsigned long pfn;
 354
 355         /* Turn a kernel-virtual address into a physical page frame */
 356         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 357
 358         /*
 359          * RED-PEN: on some architectures there is more mapped memory than
 360          * available in mem_map which pfn_valid checks for. Perhaps should add a
 361          * new macro here.
 362          *
 363          * RED-PEN: vmalloc is not supported right now.
 364          */
 365         if (!pfn_valid(pfn))
 366                 return -EIO;
 367
 368         vma->vm_pgoff = pfn;
 369         return mmap_mem(file, vma);
 370 }
 371
 372 /*
 373  * This function reads the *virtual* memory as seen by the kernel.
 374  */
 375 static ssize_t read_kmem(struct file *file, char __user *buf,
 376                          size_t count, loff_t *ppos)
 377 {
 378         unsigned long p = *ppos;
 379         ssize_t low_count, read, sz;
 380         char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 381         int err = 0;
 382
 383         read = 0;
 384         if (p < (unsigned long) high_memory) {
 385                 low_count = count;
 386                 if (count > (unsigned long)high_memory - p)
 387                         low_count = (unsigned long)high_memory - p;
 388
 389 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 390                 /* we don't have page 0 mapped on sparc and m68k.. */
 391                 if (p < PAGE_SIZE && low_count > 0) {
 392                         sz = size_inside_page(p, low_count);
 393                         if (clear_user(buf, sz))
 394                                 return -EFAULT;
 395                         buf += sz;
 396                         p += sz;
 397                         read += sz;
 398                         low_count -= sz;
 399                         count -= sz;
 400                 }
 401 #endif
 402                 while (low_count > 0) {
 403                         sz = size_inside_page(p, low_count);
 404
 405                         /*
 406                          * On ia64 if a page has been mapped somewhere as
 407                          * uncached, then it must also be accessed uncached
 408                          * by the kernel or data corruption may occur
 409                          */
 410                         kbuf = xlate_dev_kmem_ptr((void *)p);
 411
 412                         if (copy_to_user(buf, kbuf, sz))
 413                                 return -EFAULT;
 414                         buf += sz;
 415                         p += sz;
 416                         read += sz;
 417                         low_count -= sz;
 418                         count -= sz;
 419                 }
 420         }
 421
 422         if (count > 0) {
 423                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 424                 if (!kbuf)
 425                         return -ENOMEM;
 426                 while (count > 0) {
 427                         sz = size_inside_page(p, count);
 428                         if (!is_vmalloc_or_module_addr((void *)p)) {
 429                                 err = -ENXIO;
 430                                 break;
 431                         }
 432                         sz = vread(kbuf, (char *)p, sz);
 433                         if (!sz)
 434                                 break;
 435                         if (copy_to_user(buf, kbuf, sz)) {
 436                                 err = -EFAULT;
 437                                 break;
 438                         }
 439                         count -= sz;
 440                         buf += sz;
 441                         read += sz;
 442                         p += sz;
 443                 }
 444                 free_page((unsigned long)kbuf);
 445         }
 446         *ppos = p;
 447         return read ? read : err;
 448 }
 449
 450
 451 static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
 452                                 size_t count, loff_t *ppos)
 453 {
 454         ssize_t written, sz;
 455         unsigned long copied;
 456
 457         written = 0;
 458 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 459         /* we don't have page 0 mapped on sparc and m68k.. */
 460         if (p < PAGE_SIZE) {
 461                 sz = size_inside_page(p, count);
 462                 /* Hmm. Do something? */
 463                 buf += sz;
 464                 p += sz;
 465                 count -= sz;
 466                 written += sz;
 467         }
 468 #endif
 469
 470         while (count > 0) {
 471                 void *ptr;
 472
 473                 sz = size_inside_page(p, count);
 474
 475                 /*
 476                  * On ia64 if a page has been mapped somewhere as uncached, then
 477                  * it must also be accessed uncached by the kernel or data
 478                  * corruption may occur.
 479                  */
 480                 ptr = xlate_dev_kmem_ptr((void *)p);
 481
 482                 copied = copy_from_user(ptr, buf, sz);
 483                 if (copied) {
 484                         written += sz - copied;
 485                         if (written)
 486                                 break;
 487                         return -EFAULT;
 488                 }
 489                 buf += sz;
 490                 p += sz;
 491                 count -= sz;
 492                 written += sz;
 493         }
 494
 495         *ppos += written;
 496         return written;
 497 }
 498
 499 /*
 500  * This function writes to the *virtual* memory as seen by the kernel.
 501  */
 502 static ssize_t write_kmem(struct file *file, const char __user *buf,
 503                           size_t count, loff_t *ppos)
 504 {
 505         unsigned long p = *ppos;
 506         ssize_t wrote = 0;
 507         ssize_t virtr = 0;
 508         char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 509         int err = 0;
 510
 511         if (p < (unsigned long) high_memory) {
 512                 unsigned long to_write = min_t(unsigned long, count,
 513                                                (unsigned long)high_memory - p);
 514                 wrote = do_write_kmem(p, buf, to_write, ppos);
 515                 if (wrote != to_write)
 516                         return wrote;
 517                 p += wrote;
 518                 buf += wrote;
 519                 count -= wrote;
 520         }
 521
 522         if (count > 0) {
 523                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 524                 if (!kbuf)
 525                         return wrote ? wrote : -ENOMEM;
 526                 while (count > 0) {
 527                         unsigned long sz = size_inside_page(p, count);
 528                         unsigned long n;
 529
 530                         if (!is_vmalloc_or_module_addr((void *)p)) {
 531                                 err = -ENXIO;
 532                                 break;
 533                         }
 534                         n = copy_from_user(kbuf, buf, sz);
 535                         if (n) {
 536                                 err = -EFAULT;
 537                                 break;
 538                         }
 539                         vwrite(kbuf, (char *)p, sz);
 540                         count -= sz;
 541                         buf += sz;
 542                         virtr += sz;
 543                         p += sz;
 544                 }
 545                 free_page((unsigned long)kbuf);
 546         }
 547
 548         *ppos = p;
 549         return virtr + wrote ? : err;
 550 }
 551
 552 static ssize_t read_port(struct file *file, char __user *buf,
 553                          size_t count, loff_t *ppos)
 554 {
 555         unsigned long i = *ppos;
 556         char __user *tmp = buf;
 557
 558         if (!access_ok(VERIFY_WRITE, buf, count))
 559                 return -EFAULT;
 560         while (count-- > 0 && i < 65536) {
 561                 if (__put_user(inb(i), tmp) < 0)
 562                         return -EFAULT;
 563                 i++;
 564                 tmp++;
 565         }
 566         *ppos = i;
 567         return tmp-buf;
 568 }
 569
 570 static ssize_t write_port(struct file *file, const char __user *buf,
 571                           size_t count, loff_t *ppos)
 572 {
 573         unsigned long i = *ppos;
 574         const char __user *tmp = buf;
 575
 576         if (!access_ok(VERIFY_READ, buf, count))
 577                 return -EFAULT;
 578         while (count-- > 0 && i < 65536) {
 579                 char c;
 580
 581                 if (__get_user(c, tmp)) {
 582                         if (tmp > buf)
 583                                 break;
 584                         return -EFAULT;
 585                 }
 586                 outb(c, i);
 587                 i++;
 588                 tmp++;
 589         }
 590         *ppos = i;
 591         return tmp-buf;
 592 }
 593
 594 static ssize_t read_null(struct file *file, char __user *buf,
 595                          size_t count, loff_t *ppos)
 596 {
 597         return 0;
 598 }
 599
 600 static ssize_t write_null(struct file *file, const char __user *buf,
 601                           size_t count, loff_t *ppos)
 602 {
 603         return count;
 604 }
 605
 606 static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
 607 {
 608         return 0;
 609 }
 610
 611 static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
 612 {
 613         size_t count = iov_iter_count(from);
 614         iov_iter_advance(from, count);
 615         return count;
 616 }
 617
 618 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 619                         struct splice_desc *sd)
 620 {
 621         return sd->len;
 622 }
 623
 624 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
 625                                  loff_t *ppos, size_t len, unsigned int flags)
 626 {
 627         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 628 }
 629
 630 static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
 631 {
 632         size_t written = 0;
 633
 634         while (iov_iter_count(iter)) {
 635                 size_t chunk = iov_iter_count(iter), n;
 636
 637                 if (chunk > PAGE_SIZE)
 638                         chunk = PAGE_SIZE;      /* Just for latency reasons */
 639                 n = iov_iter_zero(chunk, iter);
 640                 if (!n && iov_iter_count(iter))
 641                         return written ? written : -EFAULT;
 642                 written += n;
 643                 if (signal_pending(current))
 644                         return written ? written : -ERESTARTSYS;
 645                 cond_resched();
 646         }
 647         return written;
 648 }
 649
 650 static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 651 {
 652 #ifndef CONFIG_MMU
 653         return -ENOSYS;
 654 #endif
 655         if (vma->vm_flags & VM_SHARED)
 656                 return shmem_zero_setup(vma);
 657         return 0;
 658 }
 659
 660 static ssize_t write_full(struct file *file, const char __user *buf,
 661                           size_t count, loff_t *ppos)
 662 {
 663         return -ENOSPC;
 664 }
 665
 666 /*
 667  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 668  * can fopen() both devices with "a" now.  This was previously impossible.
 669  * -- SRB.
 670  */
 671 static loff_t null_lseek(struct file *file, loff_t offset, int orig)
 672 {
 673         return file->f_pos = 0;
 674 }
 675
 676 /*
 677  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 678  * check against negative addresses: they are ok. The return value is weird,
 679  * though, in that case (0).
 680  *
 681  * also note that seeking relative to the "end of file" isn't supported:
 682  * it has no meaning, so it returns -EINVAL.
 683  */
 684 static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 685 {
 686         loff_t ret;
 687
 688         inode_lock(file_inode(file));
 689         switch (orig) {
 690         case SEEK_CUR:
 691                 offset += file->f_pos;
 692         case SEEK_SET:
 693                 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
 694                 if ((unsigned long long)offset >= -MAX_ERRNO) {
 695                         ret = -EOVERFLOW;
 696                         break;
 697                 }
 698                 file->f_pos = offset;
 699                 ret = file->f_pos;
 700                 force_successful_syscall_return();
 701                 break;
 702         default:
 703                 ret = -EINVAL;
 704         }
 705         inode_unlock(file_inode(file));
 706         return ret;
 707 }
 708
 709 static int open_port(struct inode *inode, struct file *filp)
 710 {
 711         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 712 }
 713
 714 #define zero_lseek      null_lseek
 715 #define full_lseek      null_lseek
 716 #define write_zero      write_null
 717 #define write_iter_zero write_iter_null
 718 #define open_mem        open_port
 719 #define open_kmem       open_mem
 720
 721 static const struct file_operations __maybe_unused mem_fops = {
 722         .llseek         = memory_lseek,
 723         .read           = read_mem,
 724         .write          = write_mem,
 725         .mmap           = mmap_mem,
 726         .open           = open_mem,
 727 #ifndef CONFIG_MMU
 728         .get_unmapped_area = get_unmapped_area_mem,
 729         .mmap_capabilities = memory_mmap_capabilities,
 730 #endif
 731 };
 732
 733 static const struct file_operations __maybe_unused kmem_fops = {
 734         .llseek         = memory_lseek,
 735         .read           = read_kmem,
 736         .write          = write_kmem,
 737         .mmap           = mmap_kmem,
 738         .open           = open_kmem,
 739 #ifndef CONFIG_MMU
 740         .get_unmapped_area = get_unmapped_area_mem,
 741         .mmap_capabilities = memory_mmap_capabilities,
 742 #endif
 743 };
 744
 745 static const struct file_operations null_fops = {
 746         .llseek         = null_lseek,
 747         .read           = read_null,
 748         .write          = write_null,
 749         .read_iter      = read_iter_null,
 750         .write_iter     = write_iter_null,
 751         .splice_write   = splice_write_null,
 752 };
 753
 754 static const struct file_operations __maybe_unused port_fops = {
 755         .llseek         = memory_lseek,
 756         .read           = read_port,
 757         .write          = write_port,
 758         .open           = open_port,
 759 };
 760
 761 static const struct file_operations zero_fops = {
 762         .llseek         = zero_lseek,
 763         .write          = write_zero,
 764         .read_iter      = read_iter_zero,
 765         .write_iter     = write_iter_zero,
 766         .mmap           = mmap_zero,
 767 #ifndef CONFIG_MMU
 768         .mmap_capabilities = zero_mmap_capabilities,
 769 #endif
 770 };
 771
 772 static const struct file_operations full_fops = {
 773         .llseek         = full_lseek,
 774         .read_iter      = read_iter_zero,
 775         .write          = write_full,
 776 };
 777
 778 static const struct memdev {
 779         const char *name;
 780         umode_t mode;
 781         const struct file_operations *fops;
 782         fmode_t fmode;
 783 } devlist[] = {
 784 #ifdef CONFIG_DEVMEM
 785          [1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
 786 #endif
 787 #ifdef CONFIG_DEVKMEM
 788          [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET },
 789 #endif
 790          [3] = { "null", 0666, &null_fops, 0 },
 791 #ifdef CONFIG_DEVPORT
 792          [4] = { "port", 0, &port_fops, 0 },
 793 #endif
 794          [5] = { "zero", 0666, &zero_fops, 0 },
 795          [7] = { "full", 0666, &full_fops, 0 },
 796          [8] = { "random", 0666, &random_fops, 0 },
 797          [9] = { "urandom", 0666, &urandom_fops, 0 },
 798 #ifdef CONFIG_PRINTK
 799         [11] = { "kmsg", 0644, &kmsg_fops, 0 },
 800 #endif
 801 };
 802
 803 static int memory_open(struct inode *inode, struct file *filp)
 804 {
 805         int minor;
 806         const struct memdev *dev;
 807
 808         minor = iminor(inode);
 809         if (minor >= ARRAY_SIZE(devlist))
 810                 return -ENXIO;
 811
 812         dev = &devlist[minor];
 813         if (!dev->fops)
 814                 return -ENXIO;
 815
 816         filp->f_op = dev->fops;
 817         filp->f_mode |= dev->fmode;
 818
 819         if (dev->fops->open)
 820                 return dev->fops->open(inode, filp);
 821
 822         return 0;
 823 }
 824
 825 static const struct file_operations memory_fops = {
 826         .open = memory_open,
 827         .llseek = noop_llseek,
 828 };
 829
 830 static char *mem_devnode(struct device *dev, umode_t *mode)
 831 {
 832         if (mode && devlist[MINOR(dev->devt)].mode)
 833                 *mode = devlist[MINOR(dev->devt)].mode;
 834         return NULL;
 835 }
 836
 837 static struct class *mem_class;
 838
 839 static int __init chr_dev_init(void)
 840 {
 841         int minor;
 842
 843         if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
 844                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 845
 846         mem_class = class_create(THIS_MODULE, "mem");
 847         if (IS_ERR(mem_class))
 848                 return PTR_ERR(mem_class);
 849
 850         mem_class->devnode = mem_devnode;
 851         for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
 852                 if (!devlist[minor].name)
 853                         continue;
 854
 855                 /*
 856                  * Create /dev/port?
 857                  */
 858                 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
 859                         continue;
 860
 861                 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
 862                               NULL, devlist[minor].name);
 863         }
 864
 865         return tty_init();
 866 }
 867
 868 fs_initcall(chr_dev_init);