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/shmem_fs.h>
  26 #include <linux/splice.h>
  27 #include <linux/pfn.h>
  28 #include <linux/export.h>
  29 #include <linux/io.h>
  30 #include <linux/uio.h>
  31
  32 #include <linux/uaccess.h>
  33
  34 #ifdef CONFIG_IA64
  35 # include <linux/efi.h>
  36 #endif
  37
  38 #define DEVPORT_MINOR   4
  39
  40 static inline unsigned long size_inside_page(unsigned long start,
  41                                              unsigned long size)
  42 {
  43         unsigned long sz;
  44
  45         sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
  46
  47         return min(sz, size);
  48 }
  49
  50 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  51 static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
  52 {
  53         return addr + count <= __pa(high_memory);
  54 }
  55
  56 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
  57 {
  58         return 1;
  59 }
  60 #endif
  61
  62 #ifdef CONFIG_STRICT_DEVMEM
  63 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  64 {
  65         u64 from = ((u64)pfn) << PAGE_SHIFT;
  66         u64 to = from + size;
  67         u64 cursor = from;
  68
  69         while (cursor < to) {
  70                 if (!devmem_is_allowed(pfn))
  71                         return 0;
  72                 cursor += PAGE_SIZE;
  73                 pfn++;
  74         }
  75         return 1;
  76 }
  77 #else
  78 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  79 {
  80         return 1;
  81 }
  82 #endif
  83
  84 #ifndef unxlate_dev_mem_ptr
  85 #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
  86 void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
  87 {
  88 }
  89 #endif
  90
  91 /*
  92  * This funcion reads the *physical* memory. The f_pos points directly to the
  93  * memory location.
  94  */
  95 static ssize_t read_mem(struct file *file, char __user *buf,
  96                         size_t count, loff_t *ppos)
  97 {
  98         phys_addr_t p = *ppos;
  99         ssize_t read, sz;
 100         void *ptr;
 101
 102         if (p != *ppos)
 103                 return 0;
 104
 105         if (!valid_phys_addr_range(p, count))
 106                 return -EFAULT;
 107         read = 0;
 108 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 109         /* we don't have page 0 mapped on sparc and m68k.. */
 110         if (p < PAGE_SIZE) {
 111                 sz = size_inside_page(p, count);
 112                 if (sz > 0) {
 113                         if (clear_user(buf, sz))
 114                                 return -EFAULT;
 115                         buf += sz;
 116                         p += sz;
 117                         count -= sz;
 118                         read += sz;
 119                 }
 120         }
 121 #endif
 122
 123         while (count > 0) {
 124                 unsigned long remaining;
 125
 126                 sz = size_inside_page(p, count);
 127
 128                 if (!range_is_allowed(p >> PAGE_SHIFT, count))
 129                         return -EPERM;
 130
 131                 /*
 132                  * On ia64 if a page has been mapped somewhere as uncached, then
 133                  * it must also be accessed uncached by the kernel or data
 134                  * corruption may occur.
 135                  */
 136                 ptr = xlate_dev_mem_ptr(p);
 137                 if (!ptr)
 138                         return -EFAULT;
 139
 140                 remaining = copy_to_user(buf, ptr, sz);
 141                 unxlate_dev_mem_ptr(p, ptr);
 142                 if (remaining)
 143                         return -EFAULT;
 144
 145                 buf += sz;
 146                 p += sz;
 147                 count -= sz;
 148                 read += sz;
 149         }
 150
 151         *ppos += read;
 152         return read;
 153 }
 154
 155 static ssize_t write_mem(struct file *file, const char __user *buf,
 156                          size_t count, loff_t *ppos)
 157 {
 158         phys_addr_t p = *ppos;
 159         ssize_t written, sz;
 160         unsigned long copied;
 161         void *ptr;
 162
 163         if (p != *ppos)
 164                 return -EFBIG;
 165
 166         if (!valid_phys_addr_range(p, count))
 167                 return -EFAULT;
 168
 169         written = 0;
 170
 171 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 172         /* we don't have page 0 mapped on sparc and m68k.. */
 173         if (p < PAGE_SIZE) {
 174                 sz = size_inside_page(p, count);
 175                 /* Hmm. Do something? */
 176                 buf += sz;
 177                 p += sz;
 178                 count -= sz;
 179                 written += sz;
 180         }
 181 #endif
 182
 183         while (count > 0) {
 184                 sz = size_inside_page(p, count);
 185
 186                 if (!range_is_allowed(p >> PAGE_SHIFT, sz))
 187                         return -EPERM;
 188
 189                 /*
 190                  * On ia64 if a page has been mapped somewhere as uncached, then
 191                  * it must also be accessed uncached by the kernel or data
 192                  * corruption may occur.
 193                  */
 194                 ptr = xlate_dev_mem_ptr(p);
 195                 if (!ptr) {
 196                         if (written)
 197                                 break;
 198                         return -EFAULT;
 199                 }
 200
 201                 copied = copy_from_user(ptr, buf, sz);
 202                 unxlate_dev_mem_ptr(p, ptr);
 203                 if (copied) {
 204                         written += sz - copied;
 205                         if (written)
 206                                 break;
 207                         return -EFAULT;
 208                 }
 209
 210                 buf += sz;
 211                 p += sz;
 212                 count -= sz;
 213                 written += sz;
 214         }
 215
 216         *ppos += written;
 217         return written;
 218 }
 219
 220 int __weak phys_mem_access_prot_allowed(struct file *file,
 221         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
 222 {
 223         return 1;
 224 }
 225
 226 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 227
 228 /*
 229  * Architectures vary in how they handle caching for addresses
 230  * outside of main memory.
 231  *
 232  */
 233 #ifdef pgprot_noncached
 234 static int uncached_access(struct file *file, phys_addr_t addr)
 235 {
 236 #if defined(CONFIG_IA64)
 237         /*
 238          * On ia64, we ignore O_DSYNC because we cannot tolerate memory
 239          * attribute aliases.
 240          */
 241         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
 242 #elif defined(CONFIG_MIPS)
 243         {
 244                 extern int __uncached_access(struct file *file,
 245                                              unsigned long addr);
 246
 247                 return __uncached_access(file, addr);
 248         }
 249 #else
 250         /*
 251          * Accessing memory above the top the kernel knows about or through a
 252          * file pointer
 253          * that was marked O_DSYNC will be done non-cached.
 254          */
 255         if (file->f_flags & O_DSYNC)
 256                 return 1;
 257         return addr >= __pa(high_memory);
 258 #endif
 259 }
 260 #endif
 261
 262 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 263                                      unsigned long size, pgprot_t vma_prot)
 264 {
 265 #ifdef pgprot_noncached
 266         phys_addr_t offset = pfn << PAGE_SHIFT;
 267
 268         if (uncached_access(file, offset))
 269                 return pgprot_noncached(vma_prot);
 270 #endif
 271         return vma_prot;
 272 }
 273 #endif
 274
 275 #ifndef CONFIG_MMU
 276 static unsigned long get_unmapped_area_mem(struct file *file,
 277                                            unsigned long addr,
 278                                            unsigned long len,
 279                                            unsigned long pgoff,
 280                                            unsigned long flags)
 281 {
 282         if (!valid_mmap_phys_addr_range(pgoff, len))
 283                 return (unsigned long) -EINVAL;
 284         return pgoff << PAGE_SHIFT;
 285 }
 286
 287 /* permit direct mmap, for read, write or exec */
 288 static unsigned memory_mmap_capabilities(struct file *file)
 289 {
 290         return NOMMU_MAP_DIRECT |
 291                 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
 292 }
 293
 294 static unsigned zero_mmap_capabilities(struct file *file)
 295 {
 296         return NOMMU_MAP_COPY;
 297 }
 298
 299 /* can't do an in-place private mapping if there's no MMU */
 300 static inline int private_mapping_ok(struct vm_area_struct *vma)
 301 {
 302         return vma->vm_flags & VM_MAYSHARE;
 303 }
 304 #else
 305
 306 static inline int private_mapping_ok(struct vm_area_struct *vma)
 307 {
 308         return 1;
 309 }
 310 #endif
 311
 312 static const struct vm_operations_struct mmap_mem_ops = {
 313 #ifdef CONFIG_HAVE_IOREMAP_PROT
 314         .access = generic_access_phys
 315 #endif
 316 };
 317
 318 static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 319 {
 320         size_t size = vma->vm_end - vma->vm_start;
 321
 322         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
 323                 return -EINVAL;
 324
 325         if (!private_mapping_ok(vma))
 326                 return -ENOSYS;
 327
 328         if (!range_is_allowed(vma->vm_pgoff, size))
 329                 return -EPERM;
 330
 331         if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
 332                                                 &vma->vm_page_prot))
 333                 return -EINVAL;
 334
 335         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 336                                                  size,
 337                                                  vma->vm_page_prot);
 338
 339         vma->vm_ops = &mmap_mem_ops;
 340
 341         /* Remap-pfn-range will mark the range VM_IO */
 342         if (remap_pfn_range(vma,
 343                             vma->vm_start,
 344                             vma->vm_pgoff,
 345                             size,
 346                             vma->vm_page_prot)) {
 347                 return -EAGAIN;
 348         }
 349         return 0;
 350 }
 351
 352 static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 353 {
 354         unsigned long pfn;
 355
 356         /* Turn a kernel-virtual address into a physical page frame */
 357         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 358
 359         /*
 360          * RED-PEN: on some architectures there is more mapped memory than
 361          * available in mem_map which pfn_valid checks for. Perhaps should add a
 362          * new macro here.
 363          *
 364          * RED-PEN: vmalloc is not supported right now.
 365          */
 366         if (!pfn_valid(pfn))
 367                 return -EIO;
 368
 369         vma->vm_pgoff = pfn;
 370         return mmap_mem(file, vma);
 371 }
 372
 373 /*
 374  * This function reads the *virtual* memory as seen by the kernel.
 375  */
 376 static ssize_t read_kmem(struct file *file, char __user *buf,
 377                          size_t count, loff_t *ppos)
 378 {
 379         unsigned long p = *ppos;
 380         ssize_t low_count, read, sz;
 381         char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 382         int err = 0;
 383
 384         read = 0;
 385         if (p < (unsigned long) high_memory) {
 386                 low_count = count;
 387                 if (count > (unsigned long)high_memory - p)
 388                         low_count = (unsigned long)high_memory - p;
 389
 390 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 391                 /* we don't have page 0 mapped on sparc and m68k.. */
 392                 if (p < PAGE_SIZE && low_count > 0) {
 393                         sz = size_inside_page(p, low_count);
 394                         if (clear_user(buf, sz))
 395                                 return -EFAULT;
 396                         buf += sz;
 397                         p += sz;
 398                         read += sz;
 399                         low_count -= sz;
 400                         count -= sz;
 401                 }
 402 #endif
 403                 while (low_count > 0) {
 404                         sz = size_inside_page(p, low_count);
 405
 406                         /*
 407                          * On ia64 if a page has been mapped somewhere as
 408                          * uncached, then it must also be accessed uncached
 409                          * by the kernel or data corruption may occur
 410                          */
 411                         kbuf = xlate_dev_kmem_ptr((void *)p);
 412
 413                         if (copy_to_user(buf, kbuf, sz))
 414                                 return -EFAULT;
 415                         buf += sz;
 416                         p += sz;
 417                         read += sz;
 418                         low_count -= sz;
 419                         count -= sz;
 420                 }
 421         }
 422
 423         if (count > 0) {
 424                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 425                 if (!kbuf)
 426                         return -ENOMEM;
 427                 while (count > 0) {
 428                         sz = size_inside_page(p, count);
 429                         if (!is_vmalloc_or_module_addr((void *)p)) {
 430                                 err = -ENXIO;
 431                                 break;
 432                         }
 433                         sz = vread(kbuf, (char *)p, sz);
 434                         if (!sz)
 435                                 break;
 436                         if (copy_to_user(buf, kbuf, sz)) {
 437                                 err = -EFAULT;
 438                                 break;
 439                         }
 440                         count -= sz;
 441                         buf += sz;
 442                         read += sz;
 443                         p += sz;
 444                 }
 445                 free_page((unsigned long)kbuf);
 446         }
 447         *ppos = p;
 448         return read ? read : err;
 449 }
 450
 451
 452 static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
 453                                 size_t count, loff_t *ppos)
 454 {
 455         ssize_t written, sz;
 456         unsigned long copied;
 457
 458         written = 0;
 459 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 460         /* we don't have page 0 mapped on sparc and m68k.. */
 461         if (p < PAGE_SIZE) {
 462                 sz = size_inside_page(p, count);
 463                 /* Hmm. Do something? */
 464                 buf += sz;
 465                 p += sz;
 466                 count -= sz;
 467                 written += sz;
 468         }
 469 #endif
 470
 471         while (count > 0) {
 472                 void *ptr;
 473
 474                 sz = size_inside_page(p, count);
 475
 476                 /*
 477                  * On ia64 if a page has been mapped somewhere as uncached, then
 478                  * it must also be accessed uncached by the kernel or data
 479                  * corruption may occur.
 480                  */
 481                 ptr = xlate_dev_kmem_ptr((void *)p);
 482
 483                 copied = copy_from_user(ptr, buf, sz);
 484                 if (copied) {
 485                         written += sz - copied;
 486                         if (written)
 487                                 break;
 488                         return -EFAULT;
 489                 }
 490                 buf += sz;
 491                 p += sz;
 492                 count -= sz;
 493                 written += sz;
 494         }
 495
 496         *ppos += written;
 497         return written;
 498 }
 499
 500 /*
 501  * This function writes to the *virtual* memory as seen by the kernel.
 502  */
 503 static ssize_t write_kmem(struct file *file, const char __user *buf,
 504                           size_t count, loff_t *ppos)
 505 {
 506         unsigned long p = *ppos;
 507         ssize_t wrote = 0;
 508         ssize_t virtr = 0;
 509         char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 510         int err = 0;
 511
 512         if (p < (unsigned long) high_memory) {
 513                 unsigned long to_write = min_t(unsigned long, count,
 514                                                (unsigned long)high_memory - p);
 515                 wrote = do_write_kmem(p, buf, to_write, ppos);
 516                 if (wrote != to_write)
 517                         return wrote;
 518                 p += wrote;
 519                 buf += wrote;
 520                 count -= wrote;
 521         }
 522
 523         if (count > 0) {
 524                 kbuf = (char *)__get_free_page(GFP_KERNEL);
 525                 if (!kbuf)
 526                         return wrote ? wrote : -ENOMEM;
 527                 while (count > 0) {
 528                         unsigned long sz = size_inside_page(p, count);
 529                         unsigned long n;
 530
 531                         if (!is_vmalloc_or_module_addr((void *)p)) {
 532                                 err = -ENXIO;
 533                                 break;
 534                         }
 535                         n = copy_from_user(kbuf, buf, sz);
 536                         if (n) {
 537                                 err = -EFAULT;
 538                                 break;
 539                         }
 540                         vwrite(kbuf, (char *)p, sz);
 541                         count -= sz;
 542                         buf += sz;
 543                         virtr += sz;
 544                         p += sz;
 545                 }
 546                 free_page((unsigned long)kbuf);
 547         }
 548
 549         *ppos = p;
 550         return virtr + wrote ? : err;
 551 }
 552
 553 static ssize_t read_port(struct file *file, char __user *buf,
 554                          size_t count, loff_t *ppos)
 555 {
 556         unsigned long i = *ppos;
 557         char __user *tmp = buf;
 558
 559         if (!access_ok(VERIFY_WRITE, buf, count))
 560                 return -EFAULT;
 561         while (count-- > 0 && i < 65536) {
 562                 if (__put_user(inb(i), tmp) < 0)
 563                         return -EFAULT;
 564                 i++;
 565                 tmp++;
 566         }
 567         *ppos = i;
 568         return tmp-buf;
 569 }
 570
 571 static ssize_t write_port(struct file *file, const char __user *buf,
 572                           size_t count, loff_t *ppos)
 573 {
 574         unsigned long i = *ppos;
 575         const char __user *tmp = buf;
 576
 577         if (!access_ok(VERIFY_READ, buf, count))
 578                 return -EFAULT;
 579         while (count-- > 0 && i < 65536) {
 580                 char c;
 581
 582                 if (__get_user(c, tmp)) {
 583                         if (tmp > buf)
 584                                 break;
 585                         return -EFAULT;
 586                 }
 587                 outb(c, i);
 588                 i++;
 589                 tmp++;
 590         }
 591         *ppos = i;
 592         return tmp-buf;
 593 }
 594
 595 static ssize_t read_null(struct file *file, char __user *buf,
 596                          size_t count, loff_t *ppos)
 597 {
 598         return 0;
 599 }
 600
 601 static ssize_t write_null(struct file *file, const char __user *buf,
 602                           size_t count, loff_t *ppos)
 603 {
 604         return count;
 605 }
 606
 607 static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
 608 {
 609         return 0;
 610 }
 611
 612 static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
 613 {
 614         size_t count = iov_iter_count(from);
 615         iov_iter_advance(from, count);
 616         return count;
 617 }
 618
 619 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 620                         struct splice_desc *sd)
 621 {
 622         return sd->len;
 623 }
 624
 625 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
 626                                  loff_t *ppos, size_t len, unsigned int flags)
 627 {
 628         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 629 }
 630
 631 static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
 632 {
 633         size_t written = 0;
 634
 635         while (iov_iter_count(iter)) {
 636                 size_t chunk = iov_iter_count(iter), n;
 637
 638                 if (chunk > PAGE_SIZE)
 639                         chunk = PAGE_SIZE;      /* Just for latency reasons */
 640                 n = iov_iter_zero(chunk, iter);
 641                 if (!n && iov_iter_count(iter))
 642                         return written ? written : -EFAULT;
 643                 written += n;
 644                 if (signal_pending(current))
 645                         return written ? written : -ERESTARTSYS;
 646                 cond_resched();
 647         }
 648         return written;
 649 }
 650
 651 static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 652 {
 653 #ifndef CONFIG_MMU
 654         return -ENOSYS;
 655 #endif
 656         if (vma->vm_flags & VM_SHARED)
 657                 return shmem_zero_setup(vma);
 658         return 0;
 659 }
 660
 661 static unsigned long get_unmapped_area_zero(struct file *file,
 662                                 unsigned long addr, unsigned long len,
 663                                 unsigned long pgoff, unsigned long flags)
 664 {
 665 #ifdef CONFIG_MMU
 666         if (flags & MAP_SHARED) {
 667                 /*
 668                  * mmap_zero() will call shmem_zero_setup() to create a file,
 669                  * so use shmem's get_unmapped_area in case it can be huge;
 670                  * and pass NULL for file as in mmap.c's get_unmapped_area(),
 671                  * so as not to confuse shmem with our handle on "/dev/zero".
 672                  */
 673                 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
 674         }
 675
 676         /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
 677         return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
 678 #else
 679         return -ENOSYS;
 680 #endif
 681 }
 682
 683 static ssize_t write_full(struct file *file, const char __user *buf,
 684                           size_t count, loff_t *ppos)
 685 {
 686         return -ENOSPC;
 687 }
 688
 689 /*
 690  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 691  * can fopen() both devices with "a" now.  This was previously impossible.
 692  * -- SRB.
 693  */
 694 static loff_t null_lseek(struct file *file, loff_t offset, int orig)
 695 {
 696         return file->f_pos = 0;
 697 }
 698
 699 /*
 700  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 701  * check against negative addresses: they are ok. The return value is weird,
 702  * though, in that case (0).
 703  *
 704  * also note that seeking relative to the "end of file" isn't supported:
 705  * it has no meaning, so it returns -EINVAL.
 706  */
 707 static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 708 {
 709         loff_t ret;
 710
 711         inode_lock(file_inode(file));
 712         switch (orig) {
 713         case SEEK_CUR:
 714                 offset += file->f_pos;
 715         case SEEK_SET:
 716                 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
 717                 if ((unsigned long long)offset >= -MAX_ERRNO) {
 718                         ret = -EOVERFLOW;
 719                         break;
 720                 }
 721                 file->f_pos = offset;
 722                 ret = file->f_pos;
 723                 force_successful_syscall_return();
 724                 break;
 725         default:
 726                 ret = -EINVAL;
 727         }
 728         inode_unlock(file_inode(file));
 729         return ret;
 730 }
 731
 732 static int open_port(struct inode *inode, struct file *filp)
 733 {
 734         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 735 }
 736
 737 #define zero_lseek      null_lseek
 738 #define full_lseek      null_lseek
 739 #define write_zero      write_null
 740 #define write_iter_zero write_iter_null
 741 #define open_mem        open_port
 742 #define open_kmem       open_mem
 743
 744 static const struct file_operations __maybe_unused mem_fops = {
 745         .llseek         = memory_lseek,
 746         .read           = read_mem,
 747         .write          = write_mem,
 748         .mmap           = mmap_mem,
 749         .open           = open_mem,
 750 #ifndef CONFIG_MMU
 751         .get_unmapped_area = get_unmapped_area_mem,
 752         .mmap_capabilities = memory_mmap_capabilities,
 753 #endif
 754 };
 755
 756 static const struct file_operations __maybe_unused kmem_fops = {
 757         .llseek         = memory_lseek,
 758         .read           = read_kmem,
 759         .write          = write_kmem,
 760         .mmap           = mmap_kmem,
 761         .open           = open_kmem,
 762 #ifndef CONFIG_MMU
 763         .get_unmapped_area = get_unmapped_area_mem,
 764         .mmap_capabilities = memory_mmap_capabilities,
 765 #endif
 766 };
 767
 768 static const struct file_operations null_fops = {
 769         .llseek         = null_lseek,
 770         .read           = read_null,
 771         .write          = write_null,
 772         .read_iter      = read_iter_null,
 773         .write_iter     = write_iter_null,
 774         .splice_write   = splice_write_null,
 775 };
 776
 777 static const struct file_operations __maybe_unused port_fops = {
 778         .llseek         = memory_lseek,
 779         .read           = read_port,
 780         .write          = write_port,
 781         .open           = open_port,
 782 };
 783
 784 static const struct file_operations zero_fops = {
 785         .llseek         = zero_lseek,
 786         .write          = write_zero,
 787         .read_iter      = read_iter_zero,
 788         .write_iter     = write_iter_zero,
 789         .mmap           = mmap_zero,
 790         .get_unmapped_area = get_unmapped_area_zero,
 791 #ifndef CONFIG_MMU
 792         .mmap_capabilities = zero_mmap_capabilities,
 793 #endif
 794 };
 795
 796 static const struct file_operations full_fops = {
 797         .llseek         = full_lseek,
 798         .read_iter      = read_iter_zero,
 799         .write          = write_full,
 800 };
 801
 802 static const struct memdev {
 803         const char *name;
 804         umode_t mode;
 805         const struct file_operations *fops;
 806         fmode_t fmode;
 807 } devlist[] = {
 808 #ifdef CONFIG_DEVMEM
 809          [1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
 810 #endif
 811 #ifdef CONFIG_DEVKMEM
 812          [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET },
 813 #endif
 814          [3] = { "null", 0666, &null_fops, 0 },
 815 #ifdef CONFIG_DEVPORT
 816          [4] = { "port", 0, &port_fops, 0 },
 817 #endif
 818          [5] = { "zero", 0666, &zero_fops, 0 },
 819          [7] = { "full", 0666, &full_fops, 0 },
 820          [8] = { "random", 0666, &random_fops, 0 },
 821          [9] = { "urandom", 0666, &urandom_fops, 0 },
 822 #ifdef CONFIG_PRINTK
 823         [11] = { "kmsg", 0644, &kmsg_fops, 0 },
 824 #endif
 825 };
 826
 827 static int memory_open(struct inode *inode, struct file *filp)
 828 {
 829         int minor;
 830         const struct memdev *dev;
 831
 832         minor = iminor(inode);
 833         if (minor >= ARRAY_SIZE(devlist))
 834                 return -ENXIO;
 835
 836         dev = &devlist[minor];
 837         if (!dev->fops)
 838                 return -ENXIO;
 839
 840         filp->f_op = dev->fops;
 841         filp->f_mode |= dev->fmode;
 842
 843         if (dev->fops->open)
 844                 return dev->fops->open(inode, filp);
 845
 846         return 0;
 847 }
 848
 849 static const struct file_operations memory_fops = {
 850         .open = memory_open,
 851         .llseek = noop_llseek,
 852 };
 853
 854 static char *mem_devnode(struct device *dev, umode_t *mode)
 855 {
 856         if (mode && devlist[MINOR(dev->devt)].mode)
 857                 *mode = devlist[MINOR(dev->devt)].mode;
 858         return NULL;
 859 }
 860
 861 static struct class *mem_class;
 862
 863 static int __init chr_dev_init(void)
 864 {
 865         int minor;
 866
 867         if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
 868                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 869
 870         mem_class = class_create(THIS_MODULE, "mem");
 871         if (IS_ERR(mem_class))
 872                 return PTR_ERR(mem_class);
 873
 874         mem_class->devnode = mem_devnode;
 875         for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
 876                 if (!devlist[minor].name)
 877                         continue;
 878
 879                 /*
 880                  * Create /dev/port?
 881                  */
 882                 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
 883                         continue;
 884
 885                 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
 886                               NULL, devlist[minor].name);
 887         }
 888
 889         return tty_init();
 890 }
 891
 892 fs_initcall(chr_dev_init);