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 if (!pfn_valid(PFN_DOWN(p))) 385 return -EIO; 386 387 read = 0; 388 if (p < (unsigned long) high_memory) { 389 low_count = count; 390 if (count > (unsigned long)high_memory - p) 391 low_count = (unsigned long)high_memory - p; 392 393 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 394 /* we don't have page 0 mapped on sparc and m68k.. */ 395 if (p < PAGE_SIZE && low_count > 0) { 396 sz = size_inside_page(p, low_count); 397 if (clear_user(buf, sz)) 398 return -EFAULT; 399 buf += sz; 400 p += sz; 401 read += sz; 402 low_count -= sz; 403 count -= sz; 404 } 405 #endif 406 while (low_count > 0) { 407 sz = size_inside_page(p, low_count); 408 409 /* 410 * On ia64 if a page has been mapped somewhere as 411 * uncached, then it must also be accessed uncached 412 * by the kernel or data corruption may occur 413 */ 414 kbuf = xlate_dev_kmem_ptr((void *)p); 415 416 if (copy_to_user(buf, kbuf, sz)) 417 return -EFAULT; 418 buf += sz; 419 p += sz; 420 read += sz; 421 low_count -= sz; 422 count -= sz; 423 } 424 } 425 426 if (count > 0) { 427 kbuf = (char *)__get_free_page(GFP_KERNEL); 428 if (!kbuf) 429 return -ENOMEM; 430 while (count > 0) { 431 sz = size_inside_page(p, count); 432 if (!is_vmalloc_or_module_addr((void *)p)) { 433 err = -ENXIO; 434 break; 435 } 436 sz = vread(kbuf, (char *)p, sz); 437 if (!sz) 438 break; 439 if (copy_to_user(buf, kbuf, sz)) { 440 err = -EFAULT; 441 break; 442 } 443 count -= sz; 444 buf += sz; 445 read += sz; 446 p += sz; 447 } 448 free_page((unsigned long)kbuf); 449 } 450 *ppos = p; 451 return read ? read : err; 452 } 453 454 455 static ssize_t do_write_kmem(unsigned long p, const char __user *buf, 456 size_t count, loff_t *ppos) 457 { 458 ssize_t written, sz; 459 unsigned long copied; 460 461 written = 0; 462 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 463 /* we don't have page 0 mapped on sparc and m68k.. */ 464 if (p < PAGE_SIZE) { 465 sz = size_inside_page(p, count); 466 /* Hmm. Do something? */ 467 buf += sz; 468 p += sz; 469 count -= sz; 470 written += sz; 471 } 472 #endif 473 474 while (count > 0) { 475 void *ptr; 476 477 sz = size_inside_page(p, count); 478 479 /* 480 * On ia64 if a page has been mapped somewhere as uncached, then 481 * it must also be accessed uncached by the kernel or data 482 * corruption may occur. 483 */ 484 ptr = xlate_dev_kmem_ptr((void *)p); 485 486 copied = copy_from_user(ptr, buf, sz); 487 if (copied) { 488 written += sz - copied; 489 if (written) 490 break; 491 return -EFAULT; 492 } 493 buf += sz; 494 p += sz; 495 count -= sz; 496 written += sz; 497 } 498 499 *ppos += written; 500 return written; 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 char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 513 int err = 0; 514 515 if (!pfn_valid(PFN_DOWN(p))) 516 return -EIO; 517 518 if (p < (unsigned long) high_memory) { 519 unsigned long to_write = min_t(unsigned long, count, 520 (unsigned long)high_memory - p); 521 wrote = do_write_kmem(p, buf, to_write, ppos); 522 if (wrote != to_write) 523 return wrote; 524 p += wrote; 525 buf += wrote; 526 count -= wrote; 527 } 528 529 if (count > 0) { 530 kbuf = (char *)__get_free_page(GFP_KERNEL); 531 if (!kbuf) 532 return wrote ? wrote : -ENOMEM; 533 while (count > 0) { 534 unsigned long sz = size_inside_page(p, count); 535 unsigned long n; 536 537 if (!is_vmalloc_or_module_addr((void *)p)) { 538 err = -ENXIO; 539 break; 540 } 541 n = copy_from_user(kbuf, buf, sz); 542 if (n) { 543 err = -EFAULT; 544 break; 545 } 546 vwrite(kbuf, (char *)p, sz); 547 count -= sz; 548 buf += sz; 549 virtr += sz; 550 p += sz; 551 } 552 free_page((unsigned long)kbuf); 553 } 554 555 *ppos = p; 556 return virtr + wrote ? : err; 557 } 558 559 static ssize_t read_port(struct file *file, char __user *buf, 560 size_t count, loff_t *ppos) 561 { 562 unsigned long i = *ppos; 563 char __user *tmp = buf; 564 565 if (!access_ok(VERIFY_WRITE, buf, count)) 566 return -EFAULT; 567 while (count-- > 0 && i < 65536) { 568 if (__put_user(inb(i), tmp) < 0) 569 return -EFAULT; 570 i++; 571 tmp++; 572 } 573 *ppos = i; 574 return tmp-buf; 575 } 576 577 static ssize_t write_port(struct file *file, const char __user *buf, 578 size_t count, loff_t *ppos) 579 { 580 unsigned long i = *ppos; 581 const char __user *tmp = buf; 582 583 if (!access_ok(VERIFY_READ, buf, count)) 584 return -EFAULT; 585 while (count-- > 0 && i < 65536) { 586 char c; 587 588 if (__get_user(c, tmp)) { 589 if (tmp > buf) 590 break; 591 return -EFAULT; 592 } 593 outb(c, i); 594 i++; 595 tmp++; 596 } 597 *ppos = i; 598 return tmp-buf; 599 } 600 601 static ssize_t read_null(struct file *file, char __user *buf, 602 size_t count, loff_t *ppos) 603 { 604 return 0; 605 } 606 607 static ssize_t write_null(struct file *file, const char __user *buf, 608 size_t count, loff_t *ppos) 609 { 610 return count; 611 } 612 613 static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to) 614 { 615 return 0; 616 } 617 618 static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from) 619 { 620 size_t count = iov_iter_count(from); 621 iov_iter_advance(from, count); 622 return count; 623 } 624 625 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, 626 struct splice_desc *sd) 627 { 628 return sd->len; 629 } 630 631 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, 632 loff_t *ppos, size_t len, unsigned int flags) 633 { 634 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); 635 } 636 637 static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter) 638 { 639 size_t written = 0; 640 641 while (iov_iter_count(iter)) { 642 size_t chunk = iov_iter_count(iter), n; 643 644 if (chunk > PAGE_SIZE) 645 chunk = PAGE_SIZE; /* Just for latency reasons */ 646 n = iov_iter_zero(chunk, iter); 647 if (!n && iov_iter_count(iter)) 648 return written ? written : -EFAULT; 649 written += n; 650 if (signal_pending(current)) 651 return written ? written : -ERESTARTSYS; 652 cond_resched(); 653 } 654 return written; 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 unsigned long get_unmapped_area_zero(struct file *file, 668 unsigned long addr, unsigned long len, 669 unsigned long pgoff, unsigned long flags) 670 { 671 #ifdef CONFIG_MMU 672 if (flags & MAP_SHARED) { 673 /* 674 * mmap_zero() will call shmem_zero_setup() to create a file, 675 * so use shmem's get_unmapped_area in case it can be huge; 676 * and pass NULL for file as in mmap.c's get_unmapped_area(), 677 * so as not to confuse shmem with our handle on "/dev/zero". 678 */ 679 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags); 680 } 681 682 /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */ 683 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags); 684 #else 685 return -ENOSYS; 686 #endif 687 } 688 689 static ssize_t write_full(struct file *file, const char __user *buf, 690 size_t count, loff_t *ppos) 691 { 692 return -ENOSPC; 693 } 694 695 /* 696 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 697 * can fopen() both devices with "a" now. This was previously impossible. 698 * -- SRB. 699 */ 700 static loff_t null_lseek(struct file *file, loff_t offset, int orig) 701 { 702 return file->f_pos = 0; 703 } 704 705 /* 706 * The memory devices use the full 32/64 bits of the offset, and so we cannot 707 * check against negative addresses: they are ok. The return value is weird, 708 * though, in that case (0). 709 * 710 * also note that seeking relative to the "end of file" isn't supported: 711 * it has no meaning, so it returns -EINVAL. 712 */ 713 static loff_t memory_lseek(struct file *file, loff_t offset, int orig) 714 { 715 loff_t ret; 716 717 inode_lock(file_inode(file)); 718 switch (orig) { 719 case SEEK_CUR: 720 offset += file->f_pos; 721 case SEEK_SET: 722 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ 723 if ((unsigned long long)offset >= -MAX_ERRNO) { 724 ret = -EOVERFLOW; 725 break; 726 } 727 file->f_pos = offset; 728 ret = file->f_pos; 729 force_successful_syscall_return(); 730 break; 731 default: 732 ret = -EINVAL; 733 } 734 inode_unlock(file_inode(file)); 735 return ret; 736 } 737 738 static int open_port(struct inode *inode, struct file *filp) 739 { 740 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 741 } 742 743 #define zero_lseek null_lseek 744 #define full_lseek null_lseek 745 #define write_zero write_null 746 #define write_iter_zero write_iter_null 747 #define open_mem open_port 748 #define open_kmem open_mem 749 750 static const struct file_operations __maybe_unused mem_fops = { 751 .llseek = memory_lseek, 752 .read = read_mem, 753 .write = write_mem, 754 .mmap = mmap_mem, 755 .open = open_mem, 756 #ifndef CONFIG_MMU 757 .get_unmapped_area = get_unmapped_area_mem, 758 .mmap_capabilities = memory_mmap_capabilities, 759 #endif 760 }; 761 762 static const struct file_operations __maybe_unused kmem_fops = { 763 .llseek = memory_lseek, 764 .read = read_kmem, 765 .write = write_kmem, 766 .mmap = mmap_kmem, 767 .open = open_kmem, 768 #ifndef CONFIG_MMU 769 .get_unmapped_area = get_unmapped_area_mem, 770 .mmap_capabilities = memory_mmap_capabilities, 771 #endif 772 }; 773 774 static const struct file_operations null_fops = { 775 .llseek = null_lseek, 776 .read = read_null, 777 .write = write_null, 778 .read_iter = read_iter_null, 779 .write_iter = write_iter_null, 780 .splice_write = splice_write_null, 781 }; 782 783 static const struct file_operations __maybe_unused port_fops = { 784 .llseek = memory_lseek, 785 .read = read_port, 786 .write = write_port, 787 .open = open_port, 788 }; 789 790 static const struct file_operations zero_fops = { 791 .llseek = zero_lseek, 792 .write = write_zero, 793 .read_iter = read_iter_zero, 794 .write_iter = write_iter_zero, 795 .mmap = mmap_zero, 796 .get_unmapped_area = get_unmapped_area_zero, 797 #ifndef CONFIG_MMU 798 .mmap_capabilities = zero_mmap_capabilities, 799 #endif 800 }; 801 802 static const struct file_operations full_fops = { 803 .llseek = full_lseek, 804 .read_iter = read_iter_zero, 805 .write = write_full, 806 }; 807 808 static const struct memdev { 809 const char *name; 810 umode_t mode; 811 const struct file_operations *fops; 812 fmode_t fmode; 813 } devlist[] = { 814 #ifdef CONFIG_DEVMEM 815 [1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET }, 816 #endif 817 #ifdef CONFIG_DEVKMEM 818 [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET }, 819 #endif 820 [3] = { "null", 0666, &null_fops, 0 }, 821 #ifdef CONFIG_DEVPORT 822 [4] = { "port", 0, &port_fops, 0 }, 823 #endif 824 [5] = { "zero", 0666, &zero_fops, 0 }, 825 [7] = { "full", 0666, &full_fops, 0 }, 826 [8] = { "random", 0666, &random_fops, 0 }, 827 [9] = { "urandom", 0666, &urandom_fops, 0 }, 828 #ifdef CONFIG_PRINTK 829 [11] = { "kmsg", 0644, &kmsg_fops, 0 }, 830 #endif 831 }; 832 833 static int memory_open(struct inode *inode, struct file *filp) 834 { 835 int minor; 836 const struct memdev *dev; 837 838 minor = iminor(inode); 839 if (minor >= ARRAY_SIZE(devlist)) 840 return -ENXIO; 841 842 dev = &devlist[minor]; 843 if (!dev->fops) 844 return -ENXIO; 845 846 filp->f_op = dev->fops; 847 filp->f_mode |= dev->fmode; 848 849 if (dev->fops->open) 850 return dev->fops->open(inode, filp); 851 852 return 0; 853 } 854 855 static const struct file_operations memory_fops = { 856 .open = memory_open, 857 .llseek = noop_llseek, 858 }; 859 860 static char *mem_devnode(struct device *dev, umode_t *mode) 861 { 862 if (mode && devlist[MINOR(dev->devt)].mode) 863 *mode = devlist[MINOR(dev->devt)].mode; 864 return NULL; 865 } 866 867 static struct class *mem_class; 868 869 static int __init chr_dev_init(void) 870 { 871 int minor; 872 873 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops)) 874 printk("unable to get major %d for memory devs\n", MEM_MAJOR); 875 876 mem_class = class_create(THIS_MODULE, "mem"); 877 if (IS_ERR(mem_class)) 878 return PTR_ERR(mem_class); 879 880 mem_class->devnode = mem_devnode; 881 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { 882 if (!devlist[minor].name) 883 continue; 884 885 /* 886 * Create /dev/port? 887 */ 888 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) 889 continue; 890 891 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), 892 NULL, devlist[minor].name); 893 } 894 895 return tty_init(); 896 } 897 898 fs_initcall(chr_dev_init); 899