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/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 static inline unsigned long size_inside_page(unsigned long start, 38 unsigned long size) 39 { 40 unsigned long sz; 41 42 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); 43 44 return min(sz, size); 45 } 46 47 /* 48 * Architectures vary in how they handle caching for addresses 49 * outside of main memory. 50 * 51 */ 52 static inline int uncached_access(struct file *file, unsigned long addr) 53 { 54 #if defined(CONFIG_IA64) 55 /* 56 * On ia64, we ignore O_DSYNC because we cannot tolerate memory attribute aliases. 57 */ 58 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB); 59 #elif defined(CONFIG_MIPS) 60 { 61 extern int __uncached_access(struct file *file, 62 unsigned long addr); 63 64 return __uncached_access(file, addr); 65 } 66 #else 67 /* 68 * Accessing memory above the top the kernel knows about or through a file pointer 69 * that was marked O_DSYNC will be done non-cached. 70 */ 71 if (file->f_flags & O_DSYNC) 72 return 1; 73 return addr >= __pa(high_memory); 74 #endif 75 } 76 77 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE 78 static inline int valid_phys_addr_range(unsigned long addr, size_t count) 79 { 80 if (addr + count > __pa(high_memory)) 81 return 0; 82 83 return 1; 84 } 85 86 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 87 { 88 return 1; 89 } 90 #endif 91 92 #ifdef CONFIG_STRICT_DEVMEM 93 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 94 { 95 u64 from = ((u64)pfn) << PAGE_SHIFT; 96 u64 to = from + size; 97 u64 cursor = from; 98 99 while (cursor < to) { 100 if (!devmem_is_allowed(pfn)) { 101 printk(KERN_INFO 102 "Program %s tried to access /dev/mem between %Lx->%Lx.\n", 103 current->comm, from, to); 104 return 0; 105 } 106 cursor += PAGE_SIZE; 107 pfn++; 108 } 109 return 1; 110 } 111 #else 112 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 113 { 114 return 1; 115 } 116 #endif 117 118 void __attribute__((weak)) unxlate_dev_mem_ptr(unsigned long phys, void *addr) 119 { 120 } 121 122 /* 123 * This funcion reads the *physical* memory. The f_pos points directly to the 124 * memory location. 125 */ 126 static ssize_t read_mem(struct file * file, char __user * buf, 127 size_t count, loff_t *ppos) 128 { 129 unsigned long p = *ppos; 130 ssize_t read, sz; 131 char *ptr; 132 133 if (!valid_phys_addr_range(p, count)) 134 return -EFAULT; 135 read = 0; 136 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 137 /* we don't have page 0 mapped on sparc and m68k.. */ 138 if (p < PAGE_SIZE) { 139 sz = size_inside_page(p, count); 140 if (sz > 0) { 141 if (clear_user(buf, sz)) 142 return -EFAULT; 143 buf += sz; 144 p += sz; 145 count -= sz; 146 read += sz; 147 } 148 } 149 #endif 150 151 while (count > 0) { 152 unsigned long remaining; 153 154 sz = size_inside_page(p, count); 155 156 if (!range_is_allowed(p >> PAGE_SHIFT, count)) 157 return -EPERM; 158 159 /* 160 * On ia64 if a page has been mapped somewhere as 161 * uncached, then it must also be accessed uncached 162 * by the kernel or data corruption may occur 163 */ 164 ptr = xlate_dev_mem_ptr(p); 165 if (!ptr) 166 return -EFAULT; 167 168 remaining = copy_to_user(buf, ptr, sz); 169 unxlate_dev_mem_ptr(p, ptr); 170 if (remaining) 171 return -EFAULT; 172 173 buf += sz; 174 p += sz; 175 count -= sz; 176 read += sz; 177 } 178 179 *ppos += read; 180 return read; 181 } 182 183 static ssize_t write_mem(struct file * file, const char __user * buf, 184 size_t count, loff_t *ppos) 185 { 186 unsigned long p = *ppos; 187 ssize_t written, sz; 188 unsigned long copied; 189 void *ptr; 190 191 if (!valid_phys_addr_range(p, count)) 192 return -EFAULT; 193 194 written = 0; 195 196 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 197 /* we don't have page 0 mapped on sparc and m68k.. */ 198 if (p < PAGE_SIZE) { 199 sz = size_inside_page(p, count); 200 /* Hmm. Do something? */ 201 buf += sz; 202 p += sz; 203 count -= sz; 204 written += sz; 205 } 206 #endif 207 208 while (count > 0) { 209 sz = size_inside_page(p, count); 210 211 if (!range_is_allowed(p >> PAGE_SHIFT, sz)) 212 return -EPERM; 213 214 /* 215 * On ia64 if a page has been mapped somewhere as 216 * uncached, then it must also be accessed uncached 217 * by the kernel or data corruption may occur 218 */ 219 ptr = xlate_dev_mem_ptr(p); 220 if (!ptr) { 221 if (written) 222 break; 223 return -EFAULT; 224 } 225 226 copied = copy_from_user(ptr, buf, sz); 227 unxlate_dev_mem_ptr(p, ptr); 228 if (copied) { 229 written += sz - copied; 230 if (written) 231 break; 232 return -EFAULT; 233 } 234 235 buf += sz; 236 p += sz; 237 count -= sz; 238 written += sz; 239 } 240 241 *ppos += written; 242 return written; 243 } 244 245 int __attribute__((weak)) phys_mem_access_prot_allowed(struct file *file, 246 unsigned long pfn, unsigned long size, pgprot_t *vma_prot) 247 { 248 return 1; 249 } 250 251 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT 252 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 253 unsigned long size, pgprot_t vma_prot) 254 { 255 #ifdef pgprot_noncached 256 unsigned long offset = pfn << PAGE_SHIFT; 257 258 if (uncached_access(file, offset)) 259 return pgprot_noncached(vma_prot); 260 #endif 261 return vma_prot; 262 } 263 #endif 264 265 #ifndef CONFIG_MMU 266 static unsigned long get_unmapped_area_mem(struct file *file, 267 unsigned long addr, 268 unsigned long len, 269 unsigned long pgoff, 270 unsigned long flags) 271 { 272 if (!valid_mmap_phys_addr_range(pgoff, len)) 273 return (unsigned long) -EINVAL; 274 return pgoff << PAGE_SHIFT; 275 } 276 277 /* can't do an in-place private mapping if there's no MMU */ 278 static inline int private_mapping_ok(struct vm_area_struct *vma) 279 { 280 return vma->vm_flags & VM_MAYSHARE; 281 } 282 #else 283 #define get_unmapped_area_mem NULL 284 285 static inline int private_mapping_ok(struct vm_area_struct *vma) 286 { 287 return 1; 288 } 289 #endif 290 291 static const struct vm_operations_struct mmap_mem_ops = { 292 #ifdef CONFIG_HAVE_IOREMAP_PROT 293 .access = generic_access_phys 294 #endif 295 }; 296 297 static int mmap_mem(struct file * file, struct vm_area_struct * vma) 298 { 299 size_t size = vma->vm_end - vma->vm_start; 300 301 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) 302 return -EINVAL; 303 304 if (!private_mapping_ok(vma)) 305 return -ENOSYS; 306 307 if (!range_is_allowed(vma->vm_pgoff, size)) 308 return -EPERM; 309 310 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, 311 &vma->vm_page_prot)) 312 return -EINVAL; 313 314 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, 315 size, 316 vma->vm_page_prot); 317 318 vma->vm_ops = &mmap_mem_ops; 319 320 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */ 321 if (remap_pfn_range(vma, 322 vma->vm_start, 323 vma->vm_pgoff, 324 size, 325 vma->vm_page_prot)) { 326 return -EAGAIN; 327 } 328 return 0; 329 } 330 331 #ifdef CONFIG_DEVKMEM 332 static int mmap_kmem(struct file * file, struct vm_area_struct * vma) 333 { 334 unsigned long pfn; 335 336 /* Turn a kernel-virtual address into a physical page frame */ 337 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; 338 339 /* 340 * RED-PEN: on some architectures there is more mapped memory 341 * than available in mem_map which pfn_valid checks 342 * for. Perhaps should add a new macro here. 343 * 344 * RED-PEN: vmalloc is not supported right now. 345 */ 346 if (!pfn_valid(pfn)) 347 return -EIO; 348 349 vma->vm_pgoff = pfn; 350 return mmap_mem(file, vma); 351 } 352 #endif 353 354 #ifdef CONFIG_CRASH_DUMP 355 /* 356 * Read memory corresponding to the old kernel. 357 */ 358 static ssize_t read_oldmem(struct file *file, char __user *buf, 359 size_t count, loff_t *ppos) 360 { 361 unsigned long pfn, offset; 362 size_t read = 0, csize; 363 int rc = 0; 364 365 while (count) { 366 pfn = *ppos / PAGE_SIZE; 367 if (pfn > saved_max_pfn) 368 return read; 369 370 offset = (unsigned long)(*ppos % PAGE_SIZE); 371 if (count > PAGE_SIZE - offset) 372 csize = PAGE_SIZE - offset; 373 else 374 csize = count; 375 376 rc = copy_oldmem_page(pfn, buf, csize, offset, 1); 377 if (rc < 0) 378 return rc; 379 buf += csize; 380 *ppos += csize; 381 read += csize; 382 count -= csize; 383 } 384 return read; 385 } 386 #endif 387 388 #ifdef CONFIG_DEVKMEM 389 /* 390 * This function reads the *virtual* memory as seen by the kernel. 391 */ 392 static ssize_t read_kmem(struct file *file, char __user *buf, 393 size_t count, loff_t *ppos) 394 { 395 unsigned long p = *ppos; 396 ssize_t low_count, read, sz; 397 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ 398 399 read = 0; 400 if (p < (unsigned long) high_memory) { 401 low_count = count; 402 if (count > (unsigned long) high_memory - p) 403 low_count = (unsigned long) high_memory - p; 404 405 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 406 /* we don't have page 0 mapped on sparc and m68k.. */ 407 if (p < PAGE_SIZE && low_count > 0) { 408 sz = size_inside_page(p, low_count); 409 if (clear_user(buf, sz)) 410 return -EFAULT; 411 buf += sz; 412 p += sz; 413 read += sz; 414 low_count -= sz; 415 count -= sz; 416 } 417 #endif 418 while (low_count > 0) { 419 sz = size_inside_page(p, low_count); 420 421 /* 422 * On ia64 if a page has been mapped somewhere as 423 * uncached, then it must also be accessed uncached 424 * by the kernel or data corruption may occur 425 */ 426 kbuf = xlate_dev_kmem_ptr((char *)p); 427 428 if (copy_to_user(buf, kbuf, sz)) 429 return -EFAULT; 430 buf += sz; 431 p += sz; 432 read += sz; 433 low_count -= sz; 434 count -= sz; 435 } 436 } 437 438 if (count > 0) { 439 kbuf = (char *)__get_free_page(GFP_KERNEL); 440 if (!kbuf) 441 return -ENOMEM; 442 while (count > 0) { 443 sz = size_inside_page(p, count); 444 sz = vread(kbuf, (char *)p, sz); 445 if (!sz) 446 break; 447 if (copy_to_user(buf, kbuf, sz)) { 448 free_page((unsigned long)kbuf); 449 return -EFAULT; 450 } 451 count -= sz; 452 buf += sz; 453 read += sz; 454 p += sz; 455 } 456 free_page((unsigned long)kbuf); 457 } 458 *ppos = p; 459 return read; 460 } 461 462 463 static inline ssize_t 464 do_write_kmem(unsigned long p, const char __user *buf, 465 size_t count, loff_t *ppos) 466 { 467 ssize_t written, sz; 468 unsigned long copied; 469 470 written = 0; 471 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 472 /* we don't have page 0 mapped on sparc and m68k.. */ 473 if (p < PAGE_SIZE) { 474 sz = size_inside_page(p, count); 475 /* Hmm. Do something? */ 476 buf += sz; 477 p += sz; 478 count -= sz; 479 written += sz; 480 } 481 #endif 482 483 while (count > 0) { 484 char *ptr; 485 486 sz = size_inside_page(p, count); 487 488 /* 489 * On ia64 if a page has been mapped somewhere as 490 * uncached, then it must also be accessed uncached 491 * by the kernel or data corruption may occur 492 */ 493 ptr = xlate_dev_kmem_ptr((char *)p); 494 495 copied = copy_from_user(ptr, buf, sz); 496 if (copied) { 497 written += sz - copied; 498 if (written) 499 break; 500 return -EFAULT; 501 } 502 buf += sz; 503 p += sz; 504 count -= sz; 505 written += sz; 506 } 507 508 *ppos += written; 509 return written; 510 } 511 512 513 /* 514 * This function writes to the *virtual* memory as seen by the kernel. 515 */ 516 static ssize_t write_kmem(struct file * file, const char __user * buf, 517 size_t count, loff_t *ppos) 518 { 519 unsigned long p = *ppos; 520 ssize_t wrote = 0; 521 ssize_t virtr = 0; 522 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 523 524 if (p < (unsigned long) high_memory) { 525 unsigned long to_write = min_t(unsigned long, count, 526 (unsigned long)high_memory - p); 527 wrote = do_write_kmem(p, buf, to_write, ppos); 528 if (wrote != to_write) 529 return wrote; 530 p += wrote; 531 buf += wrote; 532 count -= wrote; 533 } 534 535 if (count > 0) { 536 kbuf = (char *)__get_free_page(GFP_KERNEL); 537 if (!kbuf) 538 return wrote ? wrote : -ENOMEM; 539 while (count > 0) { 540 unsigned long sz = size_inside_page(p, count); 541 unsigned long n; 542 543 n = copy_from_user(kbuf, buf, sz); 544 if (n) { 545 if (wrote + virtr) 546 break; 547 free_page((unsigned long)kbuf); 548 return -EFAULT; 549 } 550 sz = vwrite(kbuf, (char *)p, sz); 551 count -= sz; 552 buf += sz; 553 virtr += sz; 554 p += sz; 555 } 556 free_page((unsigned long)kbuf); 557 } 558 559 *ppos = p; 560 return virtr + wrote; 561 } 562 #endif 563 564 #ifdef CONFIG_DEVPORT 565 static ssize_t read_port(struct file * file, char __user * buf, 566 size_t count, loff_t *ppos) 567 { 568 unsigned long i = *ppos; 569 char __user *tmp = buf; 570 571 if (!access_ok(VERIFY_WRITE, buf, count)) 572 return -EFAULT; 573 while (count-- > 0 && i < 65536) { 574 if (__put_user(inb(i),tmp) < 0) 575 return -EFAULT; 576 i++; 577 tmp++; 578 } 579 *ppos = i; 580 return tmp-buf; 581 } 582 583 static ssize_t write_port(struct file * file, const char __user * buf, 584 size_t count, loff_t *ppos) 585 { 586 unsigned long i = *ppos; 587 const char __user * tmp = buf; 588 589 if (!access_ok(VERIFY_READ,buf,count)) 590 return -EFAULT; 591 while (count-- > 0 && i < 65536) { 592 char c; 593 if (__get_user(c, tmp)) { 594 if (tmp > buf) 595 break; 596 return -EFAULT; 597 } 598 outb(c,i); 599 i++; 600 tmp++; 601 } 602 *ppos = i; 603 return tmp-buf; 604 } 605 #endif 606 607 static ssize_t read_null(struct file * file, char __user * buf, 608 size_t count, loff_t *ppos) 609 { 610 return 0; 611 } 612 613 static ssize_t write_null(struct file * file, const char __user * buf, 614 size_t count, loff_t *ppos) 615 { 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_zero(struct file * file, char __user * buf, 632 size_t count, loff_t *ppos) 633 { 634 size_t written; 635 636 if (!count) 637 return 0; 638 639 if (!access_ok(VERIFY_WRITE, buf, count)) 640 return -EFAULT; 641 642 written = 0; 643 while (count) { 644 unsigned long unwritten; 645 size_t chunk = count; 646 647 if (chunk > PAGE_SIZE) 648 chunk = PAGE_SIZE; /* Just for latency reasons */ 649 unwritten = __clear_user(buf, chunk); 650 written += chunk - unwritten; 651 if (unwritten) 652 break; 653 if (signal_pending(current)) 654 return written ? written : -ERESTARTSYS; 655 buf += chunk; 656 count -= chunk; 657 cond_resched(); 658 } 659 return written ? written : -EFAULT; 660 } 661 662 static int mmap_zero(struct file * file, struct vm_area_struct * vma) 663 { 664 #ifndef CONFIG_MMU 665 return -ENOSYS; 666 #endif 667 if (vma->vm_flags & VM_SHARED) 668 return shmem_zero_setup(vma); 669 return 0; 670 } 671 672 static ssize_t write_full(struct file * file, const char __user * buf, 673 size_t count, loff_t *ppos) 674 { 675 return -ENOSPC; 676 } 677 678 /* 679 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 680 * can fopen() both devices with "a" now. This was previously impossible. 681 * -- SRB. 682 */ 683 684 static loff_t null_lseek(struct file * file, loff_t offset, int orig) 685 { 686 return file->f_pos = 0; 687 } 688 689 /* 690 * The memory devices use the full 32/64 bits of the offset, and so we cannot 691 * check against negative addresses: they are ok. The return value is weird, 692 * though, in that case (0). 693 * 694 * also note that seeking relative to the "end of file" isn't supported: 695 * it has no meaning, so it returns -EINVAL. 696 */ 697 static loff_t memory_lseek(struct file * file, loff_t offset, int orig) 698 { 699 loff_t ret; 700 701 mutex_lock(&file->f_path.dentry->d_inode->i_mutex); 702 switch (orig) { 703 case 0: 704 file->f_pos = offset; 705 ret = file->f_pos; 706 force_successful_syscall_return(); 707 break; 708 case 1: 709 file->f_pos += offset; 710 ret = file->f_pos; 711 force_successful_syscall_return(); 712 break; 713 default: 714 ret = -EINVAL; 715 } 716 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); 717 return ret; 718 } 719 720 static int open_port(struct inode * inode, struct file * filp) 721 { 722 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 723 } 724 725 #define zero_lseek null_lseek 726 #define full_lseek null_lseek 727 #define write_zero write_null 728 #define read_full read_zero 729 #define open_mem open_port 730 #define open_kmem open_mem 731 #define open_oldmem open_mem 732 733 static const struct file_operations mem_fops = { 734 .llseek = memory_lseek, 735 .read = read_mem, 736 .write = write_mem, 737 .mmap = mmap_mem, 738 .open = open_mem, 739 .get_unmapped_area = get_unmapped_area_mem, 740 }; 741 742 #ifdef CONFIG_DEVKMEM 743 static const struct file_operations kmem_fops = { 744 .llseek = memory_lseek, 745 .read = read_kmem, 746 .write = write_kmem, 747 .mmap = mmap_kmem, 748 .open = open_kmem, 749 .get_unmapped_area = get_unmapped_area_mem, 750 }; 751 #endif 752 753 static const struct file_operations null_fops = { 754 .llseek = null_lseek, 755 .read = read_null, 756 .write = write_null, 757 .splice_write = splice_write_null, 758 }; 759 760 #ifdef CONFIG_DEVPORT 761 static const struct file_operations port_fops = { 762 .llseek = memory_lseek, 763 .read = read_port, 764 .write = write_port, 765 .open = open_port, 766 }; 767 #endif 768 769 static const struct file_operations zero_fops = { 770 .llseek = zero_lseek, 771 .read = read_zero, 772 .write = write_zero, 773 .mmap = mmap_zero, 774 }; 775 776 /* 777 * capabilities for /dev/zero 778 * - permits private mappings, "copies" are taken of the source of zeros 779 */ 780 static struct backing_dev_info zero_bdi = { 781 .name = "char/mem", 782 .capabilities = BDI_CAP_MAP_COPY, 783 }; 784 785 static const struct file_operations full_fops = { 786 .llseek = full_lseek, 787 .read = read_full, 788 .write = write_full, 789 }; 790 791 #ifdef CONFIG_CRASH_DUMP 792 static const struct file_operations oldmem_fops = { 793 .read = read_oldmem, 794 .open = open_oldmem, 795 }; 796 #endif 797 798 static ssize_t kmsg_write(struct file * file, const char __user * buf, 799 size_t count, loff_t *ppos) 800 { 801 char *tmp; 802 ssize_t ret; 803 804 tmp = kmalloc(count + 1, GFP_KERNEL); 805 if (tmp == NULL) 806 return -ENOMEM; 807 ret = -EFAULT; 808 if (!copy_from_user(tmp, buf, count)) { 809 tmp[count] = 0; 810 ret = printk("%s", tmp); 811 if (ret > count) 812 /* printk can add a prefix */ 813 ret = count; 814 } 815 kfree(tmp); 816 return ret; 817 } 818 819 static const struct file_operations kmsg_fops = { 820 .write = kmsg_write, 821 }; 822 823 static const struct memdev { 824 const char *name; 825 mode_t mode; 826 const struct file_operations *fops; 827 struct backing_dev_info *dev_info; 828 } devlist[] = { 829 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi }, 830 #ifdef CONFIG_DEVKMEM 831 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi }, 832 #endif 833 [3] = { "null", 0666, &null_fops, NULL }, 834 #ifdef CONFIG_DEVPORT 835 [4] = { "port", 0, &port_fops, NULL }, 836 #endif 837 [5] = { "zero", 0666, &zero_fops, &zero_bdi }, 838 [7] = { "full", 0666, &full_fops, NULL }, 839 [8] = { "random", 0666, &random_fops, NULL }, 840 [9] = { "urandom", 0666, &urandom_fops, NULL }, 841 [11] = { "kmsg", 0, &kmsg_fops, NULL }, 842 #ifdef CONFIG_CRASH_DUMP 843 [12] = { "oldmem", 0, &oldmem_fops, NULL }, 844 #endif 845 }; 846 847 static int memory_open(struct inode *inode, struct file *filp) 848 { 849 int minor; 850 const struct memdev *dev; 851 852 minor = iminor(inode); 853 if (minor >= ARRAY_SIZE(devlist)) 854 return -ENXIO; 855 856 dev = &devlist[minor]; 857 if (!dev->fops) 858 return -ENXIO; 859 860 filp->f_op = dev->fops; 861 if (dev->dev_info) 862 filp->f_mapping->backing_dev_info = dev->dev_info; 863 864 if (dev->fops->open) 865 return dev->fops->open(inode, filp); 866 867 return 0; 868 } 869 870 static const struct file_operations memory_fops = { 871 .open = memory_open, 872 }; 873 874 static char *mem_devnode(struct device *dev, mode_t *mode) 875 { 876 if (mode && devlist[MINOR(dev->devt)].mode) 877 *mode = devlist[MINOR(dev->devt)].mode; 878 return NULL; 879 } 880 881 static struct class *mem_class; 882 883 static int __init chr_dev_init(void) 884 { 885 int minor; 886 int err; 887 888 err = bdi_init(&zero_bdi); 889 if (err) 890 return err; 891 892 if (register_chrdev(MEM_MAJOR,"mem",&memory_fops)) 893 printk("unable to get major %d for memory devs\n", MEM_MAJOR); 894 895 mem_class = class_create(THIS_MODULE, "mem"); 896 mem_class->devnode = mem_devnode; 897 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { 898 if (!devlist[minor].name) 899 continue; 900 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), 901 NULL, devlist[minor].name); 902 } 903 904 return 0; 905 } 906 907 fs_initcall(chr_dev_init); 908