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/aio.h> 30 31 #include <asm/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 printk(KERN_INFO 71 "Program %s tried to access /dev/mem between %Lx->%Lx.\n", 72 current->comm, from, to); 73 return 0; 74 } 75 cursor += PAGE_SIZE; 76 pfn++; 77 } 78 return 1; 79 } 80 #else 81 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 82 { 83 return 1; 84 } 85 #endif 86 87 void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr) 88 { 89 } 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 char *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 /* can't do an in-place private mapping if there's no MMU */ 288 static inline int private_mapping_ok(struct vm_area_struct *vma) 289 { 290 return vma->vm_flags & VM_MAYSHARE; 291 } 292 #else 293 #define get_unmapped_area_mem NULL 294 295 static inline int private_mapping_ok(struct vm_area_struct *vma) 296 { 297 return 1; 298 } 299 #endif 300 301 static const struct vm_operations_struct mmap_mem_ops = { 302 #ifdef CONFIG_HAVE_IOREMAP_PROT 303 .access = generic_access_phys 304 #endif 305 }; 306 307 static int mmap_mem(struct file *file, struct vm_area_struct *vma) 308 { 309 size_t size = vma->vm_end - vma->vm_start; 310 311 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) 312 return -EINVAL; 313 314 if (!private_mapping_ok(vma)) 315 return -ENOSYS; 316 317 if (!range_is_allowed(vma->vm_pgoff, size)) 318 return -EPERM; 319 320 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, 321 &vma->vm_page_prot)) 322 return -EINVAL; 323 324 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, 325 size, 326 vma->vm_page_prot); 327 328 vma->vm_ops = &mmap_mem_ops; 329 330 /* Remap-pfn-range will mark the range VM_IO */ 331 if (remap_pfn_range(vma, 332 vma->vm_start, 333 vma->vm_pgoff, 334 size, 335 vma->vm_page_prot)) { 336 return -EAGAIN; 337 } 338 return 0; 339 } 340 341 #ifdef CONFIG_DEVKMEM 342 static int mmap_kmem(struct file *file, struct vm_area_struct *vma) 343 { 344 unsigned long pfn; 345 346 /* Turn a kernel-virtual address into a physical page frame */ 347 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; 348 349 /* 350 * RED-PEN: on some architectures there is more mapped memory than 351 * available in mem_map which pfn_valid checks for. Perhaps should add a 352 * new macro here. 353 * 354 * RED-PEN: vmalloc is not supported right now. 355 */ 356 if (!pfn_valid(pfn)) 357 return -EIO; 358 359 vma->vm_pgoff = pfn; 360 return mmap_mem(file, vma); 361 } 362 #endif 363 364 #ifdef CONFIG_DEVKMEM 365 /* 366 * This function reads the *virtual* memory as seen by the kernel. 367 */ 368 static ssize_t read_kmem(struct file *file, char __user *buf, 369 size_t count, loff_t *ppos) 370 { 371 unsigned long p = *ppos; 372 ssize_t low_count, read, sz; 373 char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ 374 int err = 0; 375 376 read = 0; 377 if (p < (unsigned long) high_memory) { 378 low_count = count; 379 if (count > (unsigned long)high_memory - p) 380 low_count = (unsigned long)high_memory - p; 381 382 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 383 /* we don't have page 0 mapped on sparc and m68k.. */ 384 if (p < PAGE_SIZE && low_count > 0) { 385 sz = size_inside_page(p, low_count); 386 if (clear_user(buf, sz)) 387 return -EFAULT; 388 buf += sz; 389 p += sz; 390 read += sz; 391 low_count -= sz; 392 count -= sz; 393 } 394 #endif 395 while (low_count > 0) { 396 sz = size_inside_page(p, low_count); 397 398 /* 399 * On ia64 if a page has been mapped somewhere as 400 * uncached, then it must also be accessed uncached 401 * by the kernel or data corruption may occur 402 */ 403 kbuf = xlate_dev_kmem_ptr((char *)p); 404 405 if (copy_to_user(buf, kbuf, sz)) 406 return -EFAULT; 407 buf += sz; 408 p += sz; 409 read += sz; 410 low_count -= sz; 411 count -= sz; 412 } 413 } 414 415 if (count > 0) { 416 kbuf = (char *)__get_free_page(GFP_KERNEL); 417 if (!kbuf) 418 return -ENOMEM; 419 while (count > 0) { 420 sz = size_inside_page(p, count); 421 if (!is_vmalloc_or_module_addr((void *)p)) { 422 err = -ENXIO; 423 break; 424 } 425 sz = vread(kbuf, (char *)p, sz); 426 if (!sz) 427 break; 428 if (copy_to_user(buf, kbuf, sz)) { 429 err = -EFAULT; 430 break; 431 } 432 count -= sz; 433 buf += sz; 434 read += sz; 435 p += sz; 436 } 437 free_page((unsigned long)kbuf); 438 } 439 *ppos = p; 440 return read ? read : err; 441 } 442 443 444 static ssize_t do_write_kmem(unsigned long p, const char __user *buf, 445 size_t count, loff_t *ppos) 446 { 447 ssize_t written, sz; 448 unsigned long copied; 449 450 written = 0; 451 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 452 /* we don't have page 0 mapped on sparc and m68k.. */ 453 if (p < PAGE_SIZE) { 454 sz = size_inside_page(p, count); 455 /* Hmm. Do something? */ 456 buf += sz; 457 p += sz; 458 count -= sz; 459 written += sz; 460 } 461 #endif 462 463 while (count > 0) { 464 char *ptr; 465 466 sz = size_inside_page(p, count); 467 468 /* 469 * On ia64 if a page has been mapped somewhere as uncached, then 470 * it must also be accessed uncached by the kernel or data 471 * corruption may occur. 472 */ 473 ptr = xlate_dev_kmem_ptr((char *)p); 474 475 copied = copy_from_user(ptr, buf, sz); 476 if (copied) { 477 written += sz - copied; 478 if (written) 479 break; 480 return -EFAULT; 481 } 482 buf += sz; 483 p += sz; 484 count -= sz; 485 written += sz; 486 } 487 488 *ppos += written; 489 return written; 490 } 491 492 /* 493 * This function writes to the *virtual* memory as seen by the kernel. 494 */ 495 static ssize_t write_kmem(struct file *file, const char __user *buf, 496 size_t count, loff_t *ppos) 497 { 498 unsigned long p = *ppos; 499 ssize_t wrote = 0; 500 ssize_t virtr = 0; 501 char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 502 int err = 0; 503 504 if (p < (unsigned long) high_memory) { 505 unsigned long to_write = min_t(unsigned long, count, 506 (unsigned long)high_memory - p); 507 wrote = do_write_kmem(p, buf, to_write, ppos); 508 if (wrote != to_write) 509 return wrote; 510 p += wrote; 511 buf += wrote; 512 count -= wrote; 513 } 514 515 if (count > 0) { 516 kbuf = (char *)__get_free_page(GFP_KERNEL); 517 if (!kbuf) 518 return wrote ? wrote : -ENOMEM; 519 while (count > 0) { 520 unsigned long sz = size_inside_page(p, count); 521 unsigned long n; 522 523 if (!is_vmalloc_or_module_addr((void *)p)) { 524 err = -ENXIO; 525 break; 526 } 527 n = copy_from_user(kbuf, buf, sz); 528 if (n) { 529 err = -EFAULT; 530 break; 531 } 532 vwrite(kbuf, (char *)p, sz); 533 count -= sz; 534 buf += sz; 535 virtr += sz; 536 p += sz; 537 } 538 free_page((unsigned long)kbuf); 539 } 540 541 *ppos = p; 542 return virtr + wrote ? : err; 543 } 544 #endif 545 546 #ifdef CONFIG_DEVPORT 547 static ssize_t read_port(struct file *file, char __user *buf, 548 size_t count, loff_t *ppos) 549 { 550 unsigned long i = *ppos; 551 char __user *tmp = buf; 552 553 if (!access_ok(VERIFY_WRITE, buf, count)) 554 return -EFAULT; 555 while (count-- > 0 && i < 65536) { 556 if (__put_user(inb(i), tmp) < 0) 557 return -EFAULT; 558 i++; 559 tmp++; 560 } 561 *ppos = i; 562 return tmp-buf; 563 } 564 565 static ssize_t write_port(struct file *file, const char __user *buf, 566 size_t count, loff_t *ppos) 567 { 568 unsigned long i = *ppos; 569 const char __user *tmp = buf; 570 571 if (!access_ok(VERIFY_READ, buf, count)) 572 return -EFAULT; 573 while (count-- > 0 && i < 65536) { 574 char c; 575 if (__get_user(c, tmp)) { 576 if (tmp > buf) 577 break; 578 return -EFAULT; 579 } 580 outb(c, i); 581 i++; 582 tmp++; 583 } 584 *ppos = i; 585 return tmp-buf; 586 } 587 #endif 588 589 static ssize_t read_null(struct file *file, char __user *buf, 590 size_t count, loff_t *ppos) 591 { 592 return 0; 593 } 594 595 static ssize_t write_null(struct file *file, const char __user *buf, 596 size_t count, loff_t *ppos) 597 { 598 return count; 599 } 600 601 static ssize_t aio_read_null(struct kiocb *iocb, const struct iovec *iov, 602 unsigned long nr_segs, loff_t pos) 603 { 604 return 0; 605 } 606 607 static ssize_t aio_write_null(struct kiocb *iocb, const struct iovec *iov, 608 unsigned long nr_segs, loff_t pos) 609 { 610 return iov_length(iov, nr_segs); 611 } 612 613 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, 614 struct splice_desc *sd) 615 { 616 return sd->len; 617 } 618 619 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, 620 loff_t *ppos, size_t len, unsigned int flags) 621 { 622 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); 623 } 624 625 static ssize_t read_zero(struct file *file, char __user *buf, 626 size_t count, loff_t *ppos) 627 { 628 size_t written; 629 630 if (!count) 631 return 0; 632 633 if (!access_ok(VERIFY_WRITE, buf, count)) 634 return -EFAULT; 635 636 written = 0; 637 while (count) { 638 unsigned long unwritten; 639 size_t chunk = count; 640 641 if (chunk > PAGE_SIZE) 642 chunk = PAGE_SIZE; /* Just for latency reasons */ 643 unwritten = __clear_user(buf, chunk); 644 written += chunk - unwritten; 645 if (unwritten) 646 break; 647 if (signal_pending(current)) 648 return written ? written : -ERESTARTSYS; 649 buf += chunk; 650 count -= chunk; 651 cond_resched(); 652 } 653 return written ? written : -EFAULT; 654 } 655 656 static ssize_t aio_read_zero(struct kiocb *iocb, const struct iovec *iov, 657 unsigned long nr_segs, loff_t pos) 658 { 659 size_t written = 0; 660 unsigned long i; 661 ssize_t ret; 662 663 for (i = 0; i < nr_segs; i++) { 664 ret = read_zero(iocb->ki_filp, iov[i].iov_base, iov[i].iov_len, 665 &pos); 666 if (ret < 0) 667 break; 668 written += ret; 669 } 670 671 return written ? written : -EFAULT; 672 } 673 674 static int mmap_zero(struct file *file, struct vm_area_struct *vma) 675 { 676 #ifndef CONFIG_MMU 677 return -ENOSYS; 678 #endif 679 if (vma->vm_flags & VM_SHARED) 680 return shmem_zero_setup(vma); 681 return 0; 682 } 683 684 static ssize_t write_full(struct file *file, const char __user *buf, 685 size_t count, loff_t *ppos) 686 { 687 return -ENOSPC; 688 } 689 690 /* 691 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 692 * can fopen() both devices with "a" now. This was previously impossible. 693 * -- SRB. 694 */ 695 static loff_t null_lseek(struct file *file, loff_t offset, int orig) 696 { 697 return file->f_pos = 0; 698 } 699 700 /* 701 * The memory devices use the full 32/64 bits of the offset, and so we cannot 702 * check against negative addresses: they are ok. The return value is weird, 703 * though, in that case (0). 704 * 705 * also note that seeking relative to the "end of file" isn't supported: 706 * it has no meaning, so it returns -EINVAL. 707 */ 708 static loff_t memory_lseek(struct file *file, loff_t offset, int orig) 709 { 710 loff_t ret; 711 712 mutex_lock(&file_inode(file)->i_mutex); 713 switch (orig) { 714 case SEEK_CUR: 715 offset += file->f_pos; 716 case SEEK_SET: 717 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ 718 if (IS_ERR_VALUE((unsigned long long)offset)) { 719 ret = -EOVERFLOW; 720 break; 721 } 722 file->f_pos = offset; 723 ret = file->f_pos; 724 force_successful_syscall_return(); 725 break; 726 default: 727 ret = -EINVAL; 728 } 729 mutex_unlock(&file_inode(file)->i_mutex); 730 return ret; 731 } 732 733 static int open_port(struct inode *inode, struct file *filp) 734 { 735 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 736 } 737 738 #define zero_lseek null_lseek 739 #define full_lseek null_lseek 740 #define write_zero write_null 741 #define read_full read_zero 742 #define aio_write_zero aio_write_null 743 #define open_mem open_port 744 #define open_kmem open_mem 745 746 static const struct file_operations mem_fops = { 747 .llseek = memory_lseek, 748 .read = read_mem, 749 .write = write_mem, 750 .mmap = mmap_mem, 751 .open = open_mem, 752 .get_unmapped_area = get_unmapped_area_mem, 753 }; 754 755 #ifdef CONFIG_DEVKMEM 756 static const struct file_operations kmem_fops = { 757 .llseek = memory_lseek, 758 .read = read_kmem, 759 .write = write_kmem, 760 .mmap = mmap_kmem, 761 .open = open_kmem, 762 .get_unmapped_area = get_unmapped_area_mem, 763 }; 764 #endif 765 766 static const struct file_operations null_fops = { 767 .llseek = null_lseek, 768 .read = read_null, 769 .write = write_null, 770 .aio_read = aio_read_null, 771 .aio_write = aio_write_null, 772 .splice_write = splice_write_null, 773 }; 774 775 #ifdef CONFIG_DEVPORT 776 static const struct file_operations port_fops = { 777 .llseek = memory_lseek, 778 .read = read_port, 779 .write = write_port, 780 .open = open_port, 781 }; 782 #endif 783 784 static const struct file_operations zero_fops = { 785 .llseek = zero_lseek, 786 .read = read_zero, 787 .write = write_zero, 788 .aio_read = aio_read_zero, 789 .aio_write = aio_write_zero, 790 .mmap = mmap_zero, 791 }; 792 793 /* 794 * capabilities for /dev/zero 795 * - permits private mappings, "copies" are taken of the source of zeros 796 * - no writeback happens 797 */ 798 static struct backing_dev_info zero_bdi = { 799 .name = "char/mem", 800 .capabilities = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK, 801 }; 802 803 static const struct file_operations full_fops = { 804 .llseek = full_lseek, 805 .read = read_full, 806 .write = write_full, 807 }; 808 809 static const struct memdev { 810 const char *name; 811 umode_t mode; 812 const struct file_operations *fops; 813 struct backing_dev_info *dev_info; 814 } devlist[] = { 815 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi }, 816 #ifdef CONFIG_DEVKMEM 817 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi }, 818 #endif 819 [3] = { "null", 0666, &null_fops, NULL }, 820 #ifdef CONFIG_DEVPORT 821 [4] = { "port", 0, &port_fops, NULL }, 822 #endif 823 [5] = { "zero", 0666, &zero_fops, &zero_bdi }, 824 [7] = { "full", 0666, &full_fops, NULL }, 825 [8] = { "random", 0666, &random_fops, NULL }, 826 [9] = { "urandom", 0666, &urandom_fops, NULL }, 827 #ifdef CONFIG_PRINTK 828 [11] = { "kmsg", 0644, &kmsg_fops, NULL }, 829 #endif 830 }; 831 832 static int memory_open(struct inode *inode, struct file *filp) 833 { 834 int minor; 835 const struct memdev *dev; 836 837 minor = iminor(inode); 838 if (minor >= ARRAY_SIZE(devlist)) 839 return -ENXIO; 840 841 dev = &devlist[minor]; 842 if (!dev->fops) 843 return -ENXIO; 844 845 filp->f_op = dev->fops; 846 if (dev->dev_info) 847 filp->f_mapping->backing_dev_info = dev->dev_info; 848 849 /* Is /dev/mem or /dev/kmem ? */ 850 if (dev->dev_info == &directly_mappable_cdev_bdi) 851 filp->f_mode |= FMODE_UNSIGNED_OFFSET; 852 853 if (dev->fops->open) 854 return dev->fops->open(inode, filp); 855 856 return 0; 857 } 858 859 static const struct file_operations memory_fops = { 860 .open = memory_open, 861 .llseek = noop_llseek, 862 }; 863 864 static char *mem_devnode(struct device *dev, umode_t *mode) 865 { 866 if (mode && devlist[MINOR(dev->devt)].mode) 867 *mode = devlist[MINOR(dev->devt)].mode; 868 return NULL; 869 } 870 871 static struct class *mem_class; 872 873 static int __init chr_dev_init(void) 874 { 875 int minor; 876 int err; 877 878 err = bdi_init(&zero_bdi); 879 if (err) 880 return err; 881 882 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops)) 883 printk("unable to get major %d for memory devs\n", MEM_MAJOR); 884 885 mem_class = class_create(THIS_MODULE, "mem"); 886 if (IS_ERR(mem_class)) 887 return PTR_ERR(mem_class); 888 889 mem_class->devnode = mem_devnode; 890 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { 891 if (!devlist[minor].name) 892 continue; 893 894 /* 895 * Create /dev/port? 896 */ 897 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) 898 continue; 899 900 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), 901 NULL, devlist[minor].name); 902 } 903 904 return tty_init(); 905 } 906 907 fs_initcall(chr_dev_init); 908