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 #include <linux/export.h> 30 31 #include <asm/uaccess.h> 32 #include <asm/io.h> 33 34 #ifdef CONFIG_IA64 35 # include <linux/efi.h> 36 #endif 37 38 static inline unsigned long size_inside_page(unsigned long start, 39 unsigned long size) 40 { 41 unsigned long sz; 42 43 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); 44 45 return min(sz, size); 46 } 47 48 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE 49 static inline int valid_phys_addr_range(unsigned long addr, size_t count) 50 { 51 return addr + count <= __pa(high_memory); 52 } 53 54 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 55 { 56 return 1; 57 } 58 #endif 59 60 #ifdef CONFIG_STRICT_DEVMEM 61 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 62 { 63 u64 from = ((u64)pfn) << PAGE_SHIFT; 64 u64 to = from + size; 65 u64 cursor = from; 66 67 while (cursor < to) { 68 if (!devmem_is_allowed(pfn)) { 69 printk(KERN_INFO 70 "Program %s tried to access /dev/mem between %Lx->%Lx.\n", 71 current->comm, from, to); 72 return 0; 73 } 74 cursor += PAGE_SIZE; 75 pfn++; 76 } 77 return 1; 78 } 79 #else 80 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 81 { 82 return 1; 83 } 84 #endif 85 86 void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr) 87 { 88 } 89 90 /* 91 * This funcion reads the *physical* memory. The f_pos points directly to the 92 * memory location. 93 */ 94 static ssize_t read_mem(struct file *file, char __user *buf, 95 size_t count, loff_t *ppos) 96 { 97 unsigned long p = *ppos; 98 ssize_t read, sz; 99 char *ptr; 100 101 if (!valid_phys_addr_range(p, count)) 102 return -EFAULT; 103 read = 0; 104 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 105 /* we don't have page 0 mapped on sparc and m68k.. */ 106 if (p < PAGE_SIZE) { 107 sz = size_inside_page(p, count); 108 if (sz > 0) { 109 if (clear_user(buf, sz)) 110 return -EFAULT; 111 buf += sz; 112 p += sz; 113 count -= sz; 114 read += sz; 115 } 116 } 117 #endif 118 119 while (count > 0) { 120 unsigned long remaining; 121 122 sz = size_inside_page(p, count); 123 124 if (!range_is_allowed(p >> PAGE_SHIFT, count)) 125 return -EPERM; 126 127 /* 128 * On ia64 if a page has been mapped somewhere as uncached, then 129 * it must also be accessed uncached by the kernel or data 130 * corruption may occur. 131 */ 132 ptr = xlate_dev_mem_ptr(p); 133 if (!ptr) 134 return -EFAULT; 135 136 remaining = copy_to_user(buf, ptr, sz); 137 unxlate_dev_mem_ptr(p, ptr); 138 if (remaining) 139 return -EFAULT; 140 141 buf += sz; 142 p += sz; 143 count -= sz; 144 read += sz; 145 } 146 147 *ppos += read; 148 return read; 149 } 150 151 static ssize_t write_mem(struct file *file, const char __user *buf, 152 size_t count, loff_t *ppos) 153 { 154 unsigned long p = *ppos; 155 ssize_t written, sz; 156 unsigned long copied; 157 void *ptr; 158 159 if (!valid_phys_addr_range(p, count)) 160 return -EFAULT; 161 162 written = 0; 163 164 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 165 /* we don't have page 0 mapped on sparc and m68k.. */ 166 if (p < PAGE_SIZE) { 167 sz = size_inside_page(p, count); 168 /* Hmm. Do something? */ 169 buf += sz; 170 p += sz; 171 count -= sz; 172 written += sz; 173 } 174 #endif 175 176 while (count > 0) { 177 sz = size_inside_page(p, count); 178 179 if (!range_is_allowed(p >> PAGE_SHIFT, sz)) 180 return -EPERM; 181 182 /* 183 * On ia64 if a page has been mapped somewhere as uncached, then 184 * it must also be accessed uncached by the kernel or data 185 * corruption may occur. 186 */ 187 ptr = xlate_dev_mem_ptr(p); 188 if (!ptr) { 189 if (written) 190 break; 191 return -EFAULT; 192 } 193 194 copied = copy_from_user(ptr, buf, sz); 195 unxlate_dev_mem_ptr(p, ptr); 196 if (copied) { 197 written += sz - copied; 198 if (written) 199 break; 200 return -EFAULT; 201 } 202 203 buf += sz; 204 p += sz; 205 count -= sz; 206 written += sz; 207 } 208 209 *ppos += written; 210 return written; 211 } 212 213 int __weak phys_mem_access_prot_allowed(struct file *file, 214 unsigned long pfn, unsigned long size, pgprot_t *vma_prot) 215 { 216 return 1; 217 } 218 219 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT 220 221 /* 222 * Architectures vary in how they handle caching for addresses 223 * outside of main memory. 224 * 225 */ 226 #ifdef pgprot_noncached 227 static int uncached_access(struct file *file, unsigned long addr) 228 { 229 #if defined(CONFIG_IA64) 230 /* 231 * On ia64, we ignore O_DSYNC because we cannot tolerate memory 232 * attribute aliases. 233 */ 234 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB); 235 #elif defined(CONFIG_MIPS) 236 { 237 extern int __uncached_access(struct file *file, 238 unsigned long addr); 239 240 return __uncached_access(file, addr); 241 } 242 #else 243 /* 244 * Accessing memory above the top the kernel knows about or through a 245 * file pointer 246 * that was marked O_DSYNC will be done non-cached. 247 */ 248 if (file->f_flags & O_DSYNC) 249 return 1; 250 return addr >= __pa(high_memory); 251 #endif 252 } 253 #endif 254 255 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 256 unsigned long size, pgprot_t vma_prot) 257 { 258 #ifdef pgprot_noncached 259 unsigned long offset = pfn << PAGE_SHIFT; 260 261 if (uncached_access(file, offset)) 262 return pgprot_noncached(vma_prot); 263 #endif 264 return vma_prot; 265 } 266 #endif 267 268 #ifndef CONFIG_MMU 269 static unsigned long get_unmapped_area_mem(struct file *file, 270 unsigned long addr, 271 unsigned long len, 272 unsigned long pgoff, 273 unsigned long flags) 274 { 275 if (!valid_mmap_phys_addr_range(pgoff, len)) 276 return (unsigned long) -EINVAL; 277 return pgoff << PAGE_SHIFT; 278 } 279 280 /* can't do an in-place private mapping if there's no MMU */ 281 static inline int private_mapping_ok(struct vm_area_struct *vma) 282 { 283 return vma->vm_flags & VM_MAYSHARE; 284 } 285 #else 286 #define get_unmapped_area_mem NULL 287 288 static inline int private_mapping_ok(struct vm_area_struct *vma) 289 { 290 return 1; 291 } 292 #endif 293 294 static const struct vm_operations_struct mmap_mem_ops = { 295 #ifdef CONFIG_HAVE_IOREMAP_PROT 296 .access = generic_access_phys 297 #endif 298 }; 299 300 static int mmap_mem(struct file *file, struct vm_area_struct *vma) 301 { 302 size_t size = vma->vm_end - vma->vm_start; 303 304 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) 305 return -EINVAL; 306 307 if (!private_mapping_ok(vma)) 308 return -ENOSYS; 309 310 if (!range_is_allowed(vma->vm_pgoff, size)) 311 return -EPERM; 312 313 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, 314 &vma->vm_page_prot)) 315 return -EINVAL; 316 317 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, 318 size, 319 vma->vm_page_prot); 320 321 vma->vm_ops = &mmap_mem_ops; 322 323 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */ 324 if (remap_pfn_range(vma, 325 vma->vm_start, 326 vma->vm_pgoff, 327 size, 328 vma->vm_page_prot)) { 329 return -EAGAIN; 330 } 331 return 0; 332 } 333 334 #ifdef CONFIG_DEVKMEM 335 static int mmap_kmem(struct file *file, struct vm_area_struct *vma) 336 { 337 unsigned long pfn; 338 339 /* Turn a kernel-virtual address into a physical page frame */ 340 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; 341 342 /* 343 * RED-PEN: on some architectures there is more mapped memory than 344 * available in mem_map which pfn_valid checks for. Perhaps should add a 345 * new macro here. 346 * 347 * RED-PEN: vmalloc is not supported right now. 348 */ 349 if (!pfn_valid(pfn)) 350 return -EIO; 351 352 vma->vm_pgoff = pfn; 353 return mmap_mem(file, vma); 354 } 355 #endif 356 357 #ifdef CONFIG_CRASH_DUMP 358 /* 359 * Read memory corresponding to the old kernel. 360 */ 361 static ssize_t read_oldmem(struct file *file, char __user *buf, 362 size_t count, loff_t *ppos) 363 { 364 unsigned long pfn, offset; 365 size_t read = 0, csize; 366 int rc = 0; 367 368 while (count) { 369 pfn = *ppos / PAGE_SIZE; 370 if (pfn > saved_max_pfn) 371 return read; 372 373 offset = (unsigned long)(*ppos % PAGE_SIZE); 374 if (count > PAGE_SIZE - offset) 375 csize = PAGE_SIZE - offset; 376 else 377 csize = count; 378 379 rc = copy_oldmem_page(pfn, buf, csize, offset, 1); 380 if (rc < 0) 381 return rc; 382 buf += csize; 383 *ppos += csize; 384 read += csize; 385 count -= csize; 386 } 387 return read; 388 } 389 #endif 390 391 #ifdef CONFIG_DEVKMEM 392 /* 393 * This function reads the *virtual* memory as seen by the kernel. 394 */ 395 static ssize_t read_kmem(struct file *file, char __user *buf, 396 size_t count, loff_t *ppos) 397 { 398 unsigned long p = *ppos; 399 ssize_t low_count, read, sz; 400 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ 401 int err = 0; 402 403 read = 0; 404 if (p < (unsigned long) high_memory) { 405 low_count = count; 406 if (count > (unsigned long)high_memory - p) 407 low_count = (unsigned long)high_memory - p; 408 409 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 410 /* we don't have page 0 mapped on sparc and m68k.. */ 411 if (p < PAGE_SIZE && low_count > 0) { 412 sz = size_inside_page(p, low_count); 413 if (clear_user(buf, sz)) 414 return -EFAULT; 415 buf += sz; 416 p += sz; 417 read += sz; 418 low_count -= sz; 419 count -= sz; 420 } 421 #endif 422 while (low_count > 0) { 423 sz = size_inside_page(p, low_count); 424 425 /* 426 * On ia64 if a page has been mapped somewhere as 427 * uncached, then it must also be accessed uncached 428 * by the kernel or data corruption may occur 429 */ 430 kbuf = xlate_dev_kmem_ptr((char *)p); 431 432 if (copy_to_user(buf, kbuf, sz)) 433 return -EFAULT; 434 buf += sz; 435 p += sz; 436 read += sz; 437 low_count -= sz; 438 count -= sz; 439 } 440 } 441 442 if (count > 0) { 443 kbuf = (char *)__get_free_page(GFP_KERNEL); 444 if (!kbuf) 445 return -ENOMEM; 446 while (count > 0) { 447 sz = size_inside_page(p, count); 448 if (!is_vmalloc_or_module_addr((void *)p)) { 449 err = -ENXIO; 450 break; 451 } 452 sz = vread(kbuf, (char *)p, sz); 453 if (!sz) 454 break; 455 if (copy_to_user(buf, kbuf, sz)) { 456 err = -EFAULT; 457 break; 458 } 459 count -= sz; 460 buf += sz; 461 read += sz; 462 p += sz; 463 } 464 free_page((unsigned long)kbuf); 465 } 466 *ppos = p; 467 return read ? read : err; 468 } 469 470 471 static ssize_t do_write_kmem(unsigned long p, const char __user *buf, 472 size_t count, loff_t *ppos) 473 { 474 ssize_t written, sz; 475 unsigned long copied; 476 477 written = 0; 478 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 479 /* we don't have page 0 mapped on sparc and m68k.. */ 480 if (p < PAGE_SIZE) { 481 sz = size_inside_page(p, count); 482 /* Hmm. Do something? */ 483 buf += sz; 484 p += sz; 485 count -= sz; 486 written += sz; 487 } 488 #endif 489 490 while (count > 0) { 491 char *ptr; 492 493 sz = size_inside_page(p, count); 494 495 /* 496 * On ia64 if a page has been mapped somewhere as uncached, then 497 * it must also be accessed uncached by the kernel or data 498 * corruption may occur. 499 */ 500 ptr = xlate_dev_kmem_ptr((char *)p); 501 502 copied = copy_from_user(ptr, buf, sz); 503 if (copied) { 504 written += sz - copied; 505 if (written) 506 break; 507 return -EFAULT; 508 } 509 buf += sz; 510 p += sz; 511 count -= sz; 512 written += sz; 513 } 514 515 *ppos += written; 516 return written; 517 } 518 519 /* 520 * This function writes to the *virtual* memory as seen by the kernel. 521 */ 522 static ssize_t write_kmem(struct file *file, const char __user *buf, 523 size_t count, loff_t *ppos) 524 { 525 unsigned long p = *ppos; 526 ssize_t wrote = 0; 527 ssize_t virtr = 0; 528 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 529 int err = 0; 530 531 if (p < (unsigned long) high_memory) { 532 unsigned long to_write = min_t(unsigned long, count, 533 (unsigned long)high_memory - p); 534 wrote = do_write_kmem(p, buf, to_write, ppos); 535 if (wrote != to_write) 536 return wrote; 537 p += wrote; 538 buf += wrote; 539 count -= wrote; 540 } 541 542 if (count > 0) { 543 kbuf = (char *)__get_free_page(GFP_KERNEL); 544 if (!kbuf) 545 return wrote ? wrote : -ENOMEM; 546 while (count > 0) { 547 unsigned long sz = size_inside_page(p, count); 548 unsigned long n; 549 550 if (!is_vmalloc_or_module_addr((void *)p)) { 551 err = -ENXIO; 552 break; 553 } 554 n = copy_from_user(kbuf, buf, sz); 555 if (n) { 556 err = -EFAULT; 557 break; 558 } 559 vwrite(kbuf, (char *)p, sz); 560 count -= sz; 561 buf += sz; 562 virtr += sz; 563 p += sz; 564 } 565 free_page((unsigned long)kbuf); 566 } 567 568 *ppos = p; 569 return virtr + wrote ? : err; 570 } 571 #endif 572 573 #ifdef CONFIG_DEVPORT 574 static ssize_t read_port(struct file *file, char __user *buf, 575 size_t count, loff_t *ppos) 576 { 577 unsigned long i = *ppos; 578 char __user *tmp = buf; 579 580 if (!access_ok(VERIFY_WRITE, buf, count)) 581 return -EFAULT; 582 while (count-- > 0 && i < 65536) { 583 if (__put_user(inb(i), tmp) < 0) 584 return -EFAULT; 585 i++; 586 tmp++; 587 } 588 *ppos = i; 589 return tmp-buf; 590 } 591 592 static ssize_t write_port(struct file *file, const char __user *buf, 593 size_t count, loff_t *ppos) 594 { 595 unsigned long i = *ppos; 596 const char __user * tmp = buf; 597 598 if (!access_ok(VERIFY_READ, buf, count)) 599 return -EFAULT; 600 while (count-- > 0 && i < 65536) { 601 char c; 602 if (__get_user(c, tmp)) { 603 if (tmp > buf) 604 break; 605 return -EFAULT; 606 } 607 outb(c, i); 608 i++; 609 tmp++; 610 } 611 *ppos = i; 612 return tmp-buf; 613 } 614 #endif 615 616 static ssize_t read_null(struct file *file, char __user *buf, 617 size_t count, loff_t *ppos) 618 { 619 return 0; 620 } 621 622 static ssize_t write_null(struct file *file, const char __user *buf, 623 size_t count, loff_t *ppos) 624 { 625 return count; 626 } 627 628 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, 629 struct splice_desc *sd) 630 { 631 return sd->len; 632 } 633 634 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, 635 loff_t *ppos, size_t len, unsigned int flags) 636 { 637 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); 638 } 639 640 static ssize_t read_zero(struct file *file, char __user *buf, 641 size_t count, loff_t *ppos) 642 { 643 size_t written; 644 645 if (!count) 646 return 0; 647 648 if (!access_ok(VERIFY_WRITE, buf, count)) 649 return -EFAULT; 650 651 written = 0; 652 while (count) { 653 unsigned long unwritten; 654 size_t chunk = count; 655 656 if (chunk > PAGE_SIZE) 657 chunk = PAGE_SIZE; /* Just for latency reasons */ 658 unwritten = __clear_user(buf, chunk); 659 written += chunk - unwritten; 660 if (unwritten) 661 break; 662 if (signal_pending(current)) 663 return written ? written : -ERESTARTSYS; 664 buf += chunk; 665 count -= chunk; 666 cond_resched(); 667 } 668 return written ? written : -EFAULT; 669 } 670 671 static int mmap_zero(struct file *file, struct vm_area_struct *vma) 672 { 673 #ifndef CONFIG_MMU 674 return -ENOSYS; 675 #endif 676 if (vma->vm_flags & VM_SHARED) 677 return shmem_zero_setup(vma); 678 return 0; 679 } 680 681 static ssize_t write_full(struct file *file, const char __user *buf, 682 size_t count, loff_t *ppos) 683 { 684 return -ENOSPC; 685 } 686 687 /* 688 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 689 * can fopen() both devices with "a" now. This was previously impossible. 690 * -- SRB. 691 */ 692 static loff_t null_lseek(struct file *file, loff_t offset, int orig) 693 { 694 return file->f_pos = 0; 695 } 696 697 /* 698 * The memory devices use the full 32/64 bits of the offset, and so we cannot 699 * check against negative addresses: they are ok. The return value is weird, 700 * though, in that case (0). 701 * 702 * also note that seeking relative to the "end of file" isn't supported: 703 * it has no meaning, so it returns -EINVAL. 704 */ 705 static loff_t memory_lseek(struct file *file, loff_t offset, int orig) 706 { 707 loff_t ret; 708 709 mutex_lock(&file->f_path.dentry->d_inode->i_mutex); 710 switch (orig) { 711 case SEEK_CUR: 712 offset += file->f_pos; 713 case SEEK_SET: 714 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ 715 if ((unsigned long long)offset >= ~0xFFFULL) { 716 ret = -EOVERFLOW; 717 break; 718 } 719 file->f_pos = offset; 720 ret = file->f_pos; 721 force_successful_syscall_return(); 722 break; 723 default: 724 ret = -EINVAL; 725 } 726 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); 727 return ret; 728 } 729 730 static int open_port(struct inode * inode, struct file * filp) 731 { 732 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 733 } 734 735 #define zero_lseek null_lseek 736 #define full_lseek null_lseek 737 #define write_zero write_null 738 #define read_full read_zero 739 #define open_mem open_port 740 #define open_kmem open_mem 741 #define open_oldmem open_mem 742 743 static const struct file_operations mem_fops = { 744 .llseek = memory_lseek, 745 .read = read_mem, 746 .write = write_mem, 747 .mmap = mmap_mem, 748 .open = open_mem, 749 .get_unmapped_area = get_unmapped_area_mem, 750 }; 751 752 #ifdef CONFIG_DEVKMEM 753 static const struct file_operations kmem_fops = { 754 .llseek = memory_lseek, 755 .read = read_kmem, 756 .write = write_kmem, 757 .mmap = mmap_kmem, 758 .open = open_kmem, 759 .get_unmapped_area = get_unmapped_area_mem, 760 }; 761 #endif 762 763 static const struct file_operations null_fops = { 764 .llseek = null_lseek, 765 .read = read_null, 766 .write = write_null, 767 .splice_write = splice_write_null, 768 }; 769 770 #ifdef CONFIG_DEVPORT 771 static const struct file_operations port_fops = { 772 .llseek = memory_lseek, 773 .read = read_port, 774 .write = write_port, 775 .open = open_port, 776 }; 777 #endif 778 779 static const struct file_operations zero_fops = { 780 .llseek = zero_lseek, 781 .read = read_zero, 782 .write = write_zero, 783 .mmap = mmap_zero, 784 }; 785 786 /* 787 * capabilities for /dev/zero 788 * - permits private mappings, "copies" are taken of the source of zeros 789 * - no writeback happens 790 */ 791 static struct backing_dev_info zero_bdi = { 792 .name = "char/mem", 793 .capabilities = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK, 794 }; 795 796 static const struct file_operations full_fops = { 797 .llseek = full_lseek, 798 .read = read_full, 799 .write = write_full, 800 }; 801 802 #ifdef CONFIG_CRASH_DUMP 803 static const struct file_operations oldmem_fops = { 804 .read = read_oldmem, 805 .open = open_oldmem, 806 .llseek = default_llseek, 807 }; 808 #endif 809 810 static ssize_t kmsg_writev(struct kiocb *iocb, const struct iovec *iv, 811 unsigned long count, loff_t pos) 812 { 813 char *line, *p; 814 int i; 815 ssize_t ret = -EFAULT; 816 size_t len = iov_length(iv, count); 817 818 line = kmalloc(len + 1, GFP_KERNEL); 819 if (line == NULL) 820 return -ENOMEM; 821 822 /* 823 * copy all vectors into a single string, to ensure we do 824 * not interleave our log line with other printk calls 825 */ 826 p = line; 827 for (i = 0; i < count; i++) { 828 if (copy_from_user(p, iv[i].iov_base, iv[i].iov_len)) 829 goto out; 830 p += iv[i].iov_len; 831 } 832 p[0] = '\0'; 833 834 ret = printk("%s", line); 835 /* printk can add a prefix */ 836 if (ret > len) 837 ret = len; 838 out: 839 kfree(line); 840 return ret; 841 } 842 843 static const struct file_operations kmsg_fops = { 844 .aio_write = kmsg_writev, 845 .llseek = noop_llseek, 846 }; 847 848 static const struct memdev { 849 const char *name; 850 umode_t mode; 851 const struct file_operations *fops; 852 struct backing_dev_info *dev_info; 853 } devlist[] = { 854 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi }, 855 #ifdef CONFIG_DEVKMEM 856 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi }, 857 #endif 858 [3] = { "null", 0666, &null_fops, NULL }, 859 #ifdef CONFIG_DEVPORT 860 [4] = { "port", 0, &port_fops, NULL }, 861 #endif 862 [5] = { "zero", 0666, &zero_fops, &zero_bdi }, 863 [7] = { "full", 0666, &full_fops, NULL }, 864 [8] = { "random", 0666, &random_fops, NULL }, 865 [9] = { "urandom", 0666, &urandom_fops, NULL }, 866 [11] = { "kmsg", 0, &kmsg_fops, NULL }, 867 #ifdef CONFIG_CRASH_DUMP 868 [12] = { "oldmem", 0, &oldmem_fops, NULL }, 869 #endif 870 }; 871 872 static int memory_open(struct inode *inode, struct file *filp) 873 { 874 int minor; 875 const struct memdev *dev; 876 877 minor = iminor(inode); 878 if (minor >= ARRAY_SIZE(devlist)) 879 return -ENXIO; 880 881 dev = &devlist[minor]; 882 if (!dev->fops) 883 return -ENXIO; 884 885 filp->f_op = dev->fops; 886 if (dev->dev_info) 887 filp->f_mapping->backing_dev_info = dev->dev_info; 888 889 /* Is /dev/mem or /dev/kmem ? */ 890 if (dev->dev_info == &directly_mappable_cdev_bdi) 891 filp->f_mode |= FMODE_UNSIGNED_OFFSET; 892 893 if (dev->fops->open) 894 return dev->fops->open(inode, filp); 895 896 return 0; 897 } 898 899 static const struct file_operations memory_fops = { 900 .open = memory_open, 901 .llseek = noop_llseek, 902 }; 903 904 static char *mem_devnode(struct device *dev, umode_t *mode) 905 { 906 if (mode && devlist[MINOR(dev->devt)].mode) 907 *mode = devlist[MINOR(dev->devt)].mode; 908 return NULL; 909 } 910 911 static struct class *mem_class; 912 913 static int __init chr_dev_init(void) 914 { 915 int minor; 916 int err; 917 918 err = bdi_init(&zero_bdi); 919 if (err) 920 return err; 921 922 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops)) 923 printk("unable to get major %d for memory devs\n", MEM_MAJOR); 924 925 mem_class = class_create(THIS_MODULE, "mem"); 926 if (IS_ERR(mem_class)) 927 return PTR_ERR(mem_class); 928 929 mem_class->devnode = mem_devnode; 930 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { 931 if (!devlist[minor].name) 932 continue; 933 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), 934 NULL, devlist[minor].name); 935 } 936 937 return tty_init(); 938 } 939 940 fs_initcall(chr_dev_init); 941