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