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 /* 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(CONFIG_IA64) 45 /* 46 * On ia64, we ignore O_DSYNC because we cannot tolerate memory attribute aliases. 47 */ 48 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB); 49 #elif defined(CONFIG_MIPS) 50 { 51 extern int __uncached_access(struct file *file, 52 unsigned long addr); 53 54 return __uncached_access(file, addr); 55 } 56 #else 57 /* 58 * Accessing memory above the top the kernel knows about or through a file pointer 59 * that was marked O_DSYNC will be done non-cached. 60 */ 61 if (file->f_flags & O_DSYNC) 62 return 1; 63 return addr >= __pa(high_memory); 64 #endif 65 } 66 67 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE 68 static inline int valid_phys_addr_range(unsigned long addr, size_t count) 69 { 70 if (addr + count > __pa(high_memory)) 71 return 0; 72 73 return 1; 74 } 75 76 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 77 { 78 return 1; 79 } 80 #endif 81 82 #ifdef CONFIG_STRICT_DEVMEM 83 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 84 { 85 u64 from = ((u64)pfn) << PAGE_SHIFT; 86 u64 to = from + size; 87 u64 cursor = from; 88 89 while (cursor < to) { 90 if (!devmem_is_allowed(pfn)) { 91 printk(KERN_INFO 92 "Program %s tried to access /dev/mem between %Lx->%Lx.\n", 93 current->comm, from, to); 94 return 0; 95 } 96 cursor += PAGE_SIZE; 97 pfn++; 98 } 99 return 1; 100 } 101 #else 102 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 103 { 104 return 1; 105 } 106 #endif 107 108 void __attribute__((weak)) unxlate_dev_mem_ptr(unsigned long phys, void *addr) 109 { 110 } 111 112 /* 113 * This funcion reads the *physical* memory. The f_pos points directly to the 114 * memory location. 115 */ 116 static ssize_t read_mem(struct file * file, char __user * buf, 117 size_t count, loff_t *ppos) 118 { 119 unsigned long p = *ppos; 120 ssize_t read, sz; 121 char *ptr; 122 123 if (!valid_phys_addr_range(p, count)) 124 return -EFAULT; 125 read = 0; 126 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 127 /* we don't have page 0 mapped on sparc and m68k.. */ 128 if (p < PAGE_SIZE) { 129 sz = PAGE_SIZE - p; 130 if (sz > count) 131 sz = count; 132 if (sz > 0) { 133 if (clear_user(buf, sz)) 134 return -EFAULT; 135 buf += sz; 136 p += sz; 137 count -= sz; 138 read += sz; 139 } 140 } 141 #endif 142 143 while (count > 0) { 144 /* 145 * Handle first page in case it's not aligned 146 */ 147 if (-p & (PAGE_SIZE - 1)) 148 sz = -p & (PAGE_SIZE - 1); 149 else 150 sz = PAGE_SIZE; 151 152 sz = min_t(unsigned long, sz, count); 153 154 if (!range_is_allowed(p >> PAGE_SHIFT, count)) 155 return -EPERM; 156 157 /* 158 * On ia64 if a page has been mapped somewhere as 159 * uncached, then it must also be accessed uncached 160 * by the kernel or data corruption may occur 161 */ 162 ptr = xlate_dev_mem_ptr(p); 163 if (!ptr) 164 return -EFAULT; 165 166 if (copy_to_user(buf, ptr, sz)) { 167 unxlate_dev_mem_ptr(p, ptr); 168 return -EFAULT; 169 } 170 171 unxlate_dev_mem_ptr(p, ptr); 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 unsigned long sz = PAGE_SIZE - p; 200 if (sz > count) 201 sz = count; 202 /* Hmm. Do something? */ 203 buf += sz; 204 p += sz; 205 count -= sz; 206 written += sz; 207 } 208 #endif 209 210 while (count > 0) { 211 /* 212 * Handle first page in case it's not aligned 213 */ 214 if (-p & (PAGE_SIZE - 1)) 215 sz = -p & (PAGE_SIZE - 1); 216 else 217 sz = PAGE_SIZE; 218 219 sz = min_t(unsigned long, sz, count); 220 221 if (!range_is_allowed(p >> PAGE_SHIFT, sz)) 222 return -EPERM; 223 224 /* 225 * On ia64 if a page has been mapped somewhere as 226 * uncached, then it must also be accessed uncached 227 * by the kernel or data corruption may occur 228 */ 229 ptr = xlate_dev_mem_ptr(p); 230 if (!ptr) { 231 if (written) 232 break; 233 return -EFAULT; 234 } 235 236 copied = copy_from_user(ptr, buf, sz); 237 if (copied) { 238 written += sz - copied; 239 unxlate_dev_mem_ptr(p, ptr); 240 if (written) 241 break; 242 return -EFAULT; 243 } 244 245 unxlate_dev_mem_ptr(p, ptr); 246 247 buf += sz; 248 p += sz; 249 count -= sz; 250 written += sz; 251 } 252 253 *ppos += written; 254 return written; 255 } 256 257 int __attribute__((weak)) phys_mem_access_prot_allowed(struct file *file, 258 unsigned long pfn, unsigned long size, pgprot_t *vma_prot) 259 { 260 return 1; 261 } 262 263 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT 264 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 265 unsigned long size, pgprot_t vma_prot) 266 { 267 #ifdef pgprot_noncached 268 unsigned long offset = pfn << PAGE_SHIFT; 269 270 if (uncached_access(file, offset)) 271 return pgprot_noncached(vma_prot); 272 #endif 273 return vma_prot; 274 } 275 #endif 276 277 #ifndef CONFIG_MMU 278 static unsigned long get_unmapped_area_mem(struct file *file, 279 unsigned long addr, 280 unsigned long len, 281 unsigned long pgoff, 282 unsigned long flags) 283 { 284 if (!valid_mmap_phys_addr_range(pgoff, len)) 285 return (unsigned long) -EINVAL; 286 return pgoff << PAGE_SHIFT; 287 } 288 289 /* can't do an in-place private mapping if there's no MMU */ 290 static inline int private_mapping_ok(struct vm_area_struct *vma) 291 { 292 return vma->vm_flags & VM_MAYSHARE; 293 } 294 #else 295 #define get_unmapped_area_mem NULL 296 297 static inline int private_mapping_ok(struct vm_area_struct *vma) 298 { 299 return 1; 300 } 301 #endif 302 303 static const struct vm_operations_struct mmap_mem_ops = { 304 #ifdef CONFIG_HAVE_IOREMAP_PROT 305 .access = generic_access_phys 306 #endif 307 }; 308 309 static int mmap_mem(struct file * file, struct vm_area_struct * vma) 310 { 311 size_t size = vma->vm_end - vma->vm_start; 312 313 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) 314 return -EINVAL; 315 316 if (!private_mapping_ok(vma)) 317 return -ENOSYS; 318 319 if (!range_is_allowed(vma->vm_pgoff, size)) 320 return -EPERM; 321 322 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, 323 &vma->vm_page_prot)) 324 return -EINVAL; 325 326 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, 327 size, 328 vma->vm_page_prot); 329 330 vma->vm_ops = &mmap_mem_ops; 331 332 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */ 333 if (remap_pfn_range(vma, 334 vma->vm_start, 335 vma->vm_pgoff, 336 size, 337 vma->vm_page_prot)) { 338 return -EAGAIN; 339 } 340 return 0; 341 } 342 343 #ifdef CONFIG_DEVKMEM 344 static int mmap_kmem(struct file * file, struct vm_area_struct * vma) 345 { 346 unsigned long pfn; 347 348 /* Turn a kernel-virtual address into a physical page frame */ 349 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; 350 351 /* 352 * RED-PEN: on some architectures there is more mapped memory 353 * than available in mem_map which pfn_valid checks 354 * for. Perhaps should add a new macro here. 355 * 356 * RED-PEN: vmalloc is not supported right now. 357 */ 358 if (!pfn_valid(pfn)) 359 return -EIO; 360 361 vma->vm_pgoff = pfn; 362 return mmap_mem(file, vma); 363 } 364 #endif 365 366 #ifdef CONFIG_CRASH_DUMP 367 /* 368 * Read memory corresponding to the old kernel. 369 */ 370 static ssize_t read_oldmem(struct file *file, char __user *buf, 371 size_t count, loff_t *ppos) 372 { 373 unsigned long pfn, offset; 374 size_t read = 0, csize; 375 int rc = 0; 376 377 while (count) { 378 pfn = *ppos / PAGE_SIZE; 379 if (pfn > saved_max_pfn) 380 return read; 381 382 offset = (unsigned long)(*ppos % PAGE_SIZE); 383 if (count > PAGE_SIZE - offset) 384 csize = PAGE_SIZE - offset; 385 else 386 csize = count; 387 388 rc = copy_oldmem_page(pfn, buf, csize, offset, 1); 389 if (rc < 0) 390 return rc; 391 buf += csize; 392 *ppos += csize; 393 read += csize; 394 count -= csize; 395 } 396 return read; 397 } 398 #endif 399 400 #ifdef CONFIG_DEVKMEM 401 /* 402 * This function reads the *virtual* memory as seen by the kernel. 403 */ 404 static ssize_t read_kmem(struct file *file, char __user *buf, 405 size_t count, loff_t *ppos) 406 { 407 unsigned long p = *ppos; 408 ssize_t low_count, read, sz; 409 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ 410 411 read = 0; 412 if (p < (unsigned long) high_memory) { 413 low_count = count; 414 if (count > (unsigned long) high_memory - p) 415 low_count = (unsigned long) high_memory - p; 416 417 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 418 /* we don't have page 0 mapped on sparc and m68k.. */ 419 if (p < PAGE_SIZE && low_count > 0) { 420 size_t tmp = PAGE_SIZE - p; 421 if (tmp > low_count) tmp = low_count; 422 if (clear_user(buf, tmp)) 423 return -EFAULT; 424 buf += tmp; 425 p += tmp; 426 read += tmp; 427 low_count -= tmp; 428 count -= tmp; 429 } 430 #endif 431 while (low_count > 0) { 432 /* 433 * Handle first page in case it's not aligned 434 */ 435 if (-p & (PAGE_SIZE - 1)) 436 sz = -p & (PAGE_SIZE - 1); 437 else 438 sz = PAGE_SIZE; 439 440 sz = min_t(unsigned long, sz, low_count); 441 442 /* 443 * On ia64 if a page has been mapped somewhere as 444 * uncached, then it must also be accessed uncached 445 * by the kernel or data corruption may occur 446 */ 447 kbuf = xlate_dev_kmem_ptr((char *)p); 448 449 if (copy_to_user(buf, kbuf, sz)) 450 return -EFAULT; 451 buf += sz; 452 p += sz; 453 read += sz; 454 low_count -= sz; 455 count -= sz; 456 } 457 } 458 459 if (count > 0) { 460 kbuf = (char *)__get_free_page(GFP_KERNEL); 461 if (!kbuf) 462 return -ENOMEM; 463 while (count > 0) { 464 int len = count; 465 466 if (len > PAGE_SIZE) 467 len = PAGE_SIZE; 468 len = vread(kbuf, (char *)p, len); 469 if (!len) 470 break; 471 if (copy_to_user(buf, kbuf, len)) { 472 free_page((unsigned long)kbuf); 473 return -EFAULT; 474 } 475 count -= len; 476 buf += len; 477 read += len; 478 p += len; 479 } 480 free_page((unsigned long)kbuf); 481 } 482 *ppos = p; 483 return read; 484 } 485 486 487 static inline ssize_t 488 do_write_kmem(void *p, unsigned long realp, const char __user * buf, 489 size_t count, loff_t *ppos) 490 { 491 ssize_t written, sz; 492 unsigned long copied; 493 494 written = 0; 495 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 496 /* we don't have page 0 mapped on sparc and m68k.. */ 497 if (realp < PAGE_SIZE) { 498 unsigned long sz = PAGE_SIZE - realp; 499 if (sz > count) 500 sz = count; 501 /* Hmm. Do something? */ 502 buf += sz; 503 p += sz; 504 realp += sz; 505 count -= sz; 506 written += sz; 507 } 508 #endif 509 510 while (count > 0) { 511 char *ptr; 512 /* 513 * Handle first page in case it's not aligned 514 */ 515 if (-realp & (PAGE_SIZE - 1)) 516 sz = -realp & (PAGE_SIZE - 1); 517 else 518 sz = PAGE_SIZE; 519 520 sz = min_t(unsigned long, sz, count); 521 522 /* 523 * On ia64 if a page has been mapped somewhere as 524 * uncached, then it must also be accessed uncached 525 * by the kernel or data corruption may occur 526 */ 527 ptr = xlate_dev_kmem_ptr(p); 528 529 copied = copy_from_user(ptr, buf, sz); 530 if (copied) { 531 written += sz - copied; 532 if (written) 533 break; 534 return -EFAULT; 535 } 536 buf += sz; 537 p += sz; 538 realp += sz; 539 count -= sz; 540 written += sz; 541 } 542 543 *ppos += written; 544 return written; 545 } 546 547 548 /* 549 * This function writes to the *virtual* memory as seen by the kernel. 550 */ 551 static ssize_t write_kmem(struct file * file, const char __user * buf, 552 size_t count, loff_t *ppos) 553 { 554 unsigned long p = *ppos; 555 ssize_t wrote = 0; 556 ssize_t virtr = 0; 557 ssize_t written; 558 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 559 560 if (p < (unsigned long) high_memory) { 561 562 wrote = count; 563 if (count > (unsigned long) high_memory - p) 564 wrote = (unsigned long) high_memory - p; 565 566 written = do_write_kmem((void*)p, p, buf, wrote, ppos); 567 if (written != wrote) 568 return written; 569 wrote = written; 570 p += wrote; 571 buf += wrote; 572 count -= wrote; 573 } 574 575 if (count > 0) { 576 kbuf = (char *)__get_free_page(GFP_KERNEL); 577 if (!kbuf) 578 return wrote ? wrote : -ENOMEM; 579 while (count > 0) { 580 int len = count; 581 582 if (len > PAGE_SIZE) 583 len = PAGE_SIZE; 584 if (len) { 585 written = copy_from_user(kbuf, buf, len); 586 if (written) { 587 if (wrote + virtr) 588 break; 589 free_page((unsigned long)kbuf); 590 return -EFAULT; 591 } 592 } 593 len = vwrite(kbuf, (char *)p, len); 594 count -= len; 595 buf += len; 596 virtr += len; 597 p += len; 598 } 599 free_page((unsigned long)kbuf); 600 } 601 602 *ppos = p; 603 return virtr + wrote; 604 } 605 #endif 606 607 #ifdef CONFIG_DEVPORT 608 static ssize_t read_port(struct file * file, char __user * buf, 609 size_t count, loff_t *ppos) 610 { 611 unsigned long i = *ppos; 612 char __user *tmp = buf; 613 614 if (!access_ok(VERIFY_WRITE, buf, count)) 615 return -EFAULT; 616 while (count-- > 0 && i < 65536) { 617 if (__put_user(inb(i),tmp) < 0) 618 return -EFAULT; 619 i++; 620 tmp++; 621 } 622 *ppos = i; 623 return tmp-buf; 624 } 625 626 static ssize_t write_port(struct file * file, const char __user * buf, 627 size_t count, loff_t *ppos) 628 { 629 unsigned long i = *ppos; 630 const char __user * tmp = buf; 631 632 if (!access_ok(VERIFY_READ,buf,count)) 633 return -EFAULT; 634 while (count-- > 0 && i < 65536) { 635 char c; 636 if (__get_user(c, tmp)) { 637 if (tmp > buf) 638 break; 639 return -EFAULT; 640 } 641 outb(c,i); 642 i++; 643 tmp++; 644 } 645 *ppos = i; 646 return tmp-buf; 647 } 648 #endif 649 650 static ssize_t read_null(struct file * file, char __user * buf, 651 size_t count, loff_t *ppos) 652 { 653 return 0; 654 } 655 656 static ssize_t write_null(struct file * file, const char __user * buf, 657 size_t count, loff_t *ppos) 658 { 659 return count; 660 } 661 662 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, 663 struct splice_desc *sd) 664 { 665 return sd->len; 666 } 667 668 static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out, 669 loff_t *ppos, size_t len, unsigned int flags) 670 { 671 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); 672 } 673 674 static ssize_t read_zero(struct file * file, char __user * buf, 675 size_t count, loff_t *ppos) 676 { 677 size_t written; 678 679 if (!count) 680 return 0; 681 682 if (!access_ok(VERIFY_WRITE, buf, count)) 683 return -EFAULT; 684 685 written = 0; 686 while (count) { 687 unsigned long unwritten; 688 size_t chunk = count; 689 690 if (chunk > PAGE_SIZE) 691 chunk = PAGE_SIZE; /* Just for latency reasons */ 692 unwritten = __clear_user(buf, chunk); 693 written += chunk - unwritten; 694 if (unwritten) 695 break; 696 if (signal_pending(current)) 697 return written ? written : -ERESTARTSYS; 698 buf += chunk; 699 count -= chunk; 700 cond_resched(); 701 } 702 return written ? written : -EFAULT; 703 } 704 705 static int mmap_zero(struct file * file, struct vm_area_struct * vma) 706 { 707 #ifndef CONFIG_MMU 708 return -ENOSYS; 709 #endif 710 if (vma->vm_flags & VM_SHARED) 711 return shmem_zero_setup(vma); 712 return 0; 713 } 714 715 static ssize_t write_full(struct file * file, const char __user * buf, 716 size_t count, loff_t *ppos) 717 { 718 return -ENOSPC; 719 } 720 721 /* 722 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 723 * can fopen() both devices with "a" now. This was previously impossible. 724 * -- SRB. 725 */ 726 727 static loff_t null_lseek(struct file * file, loff_t offset, int orig) 728 { 729 return file->f_pos = 0; 730 } 731 732 /* 733 * The memory devices use the full 32/64 bits of the offset, and so we cannot 734 * check against negative addresses: they are ok. The return value is weird, 735 * though, in that case (0). 736 * 737 * also note that seeking relative to the "end of file" isn't supported: 738 * it has no meaning, so it returns -EINVAL. 739 */ 740 static loff_t memory_lseek(struct file * file, loff_t offset, int orig) 741 { 742 loff_t ret; 743 744 mutex_lock(&file->f_path.dentry->d_inode->i_mutex); 745 switch (orig) { 746 case 0: 747 file->f_pos = offset; 748 ret = file->f_pos; 749 force_successful_syscall_return(); 750 break; 751 case 1: 752 file->f_pos += offset; 753 ret = file->f_pos; 754 force_successful_syscall_return(); 755 break; 756 default: 757 ret = -EINVAL; 758 } 759 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); 760 return ret; 761 } 762 763 static int open_port(struct inode * inode, struct file * filp) 764 { 765 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 766 } 767 768 #define zero_lseek null_lseek 769 #define full_lseek null_lseek 770 #define write_zero write_null 771 #define read_full read_zero 772 #define open_mem open_port 773 #define open_kmem open_mem 774 #define open_oldmem open_mem 775 776 static const struct file_operations mem_fops = { 777 .llseek = memory_lseek, 778 .read = read_mem, 779 .write = write_mem, 780 .mmap = mmap_mem, 781 .open = open_mem, 782 .get_unmapped_area = get_unmapped_area_mem, 783 }; 784 785 #ifdef CONFIG_DEVKMEM 786 static const struct file_operations kmem_fops = { 787 .llseek = memory_lseek, 788 .read = read_kmem, 789 .write = write_kmem, 790 .mmap = mmap_kmem, 791 .open = open_kmem, 792 .get_unmapped_area = get_unmapped_area_mem, 793 }; 794 #endif 795 796 static const struct file_operations null_fops = { 797 .llseek = null_lseek, 798 .read = read_null, 799 .write = write_null, 800 .splice_write = splice_write_null, 801 }; 802 803 #ifdef CONFIG_DEVPORT 804 static const struct file_operations port_fops = { 805 .llseek = memory_lseek, 806 .read = read_port, 807 .write = write_port, 808 .open = open_port, 809 }; 810 #endif 811 812 static const struct file_operations zero_fops = { 813 .llseek = zero_lseek, 814 .read = read_zero, 815 .write = write_zero, 816 .mmap = mmap_zero, 817 }; 818 819 /* 820 * capabilities for /dev/zero 821 * - permits private mappings, "copies" are taken of the source of zeros 822 */ 823 static struct backing_dev_info zero_bdi = { 824 .name = "char/mem", 825 .capabilities = BDI_CAP_MAP_COPY, 826 }; 827 828 static const struct file_operations full_fops = { 829 .llseek = full_lseek, 830 .read = read_full, 831 .write = write_full, 832 }; 833 834 #ifdef CONFIG_CRASH_DUMP 835 static const struct file_operations oldmem_fops = { 836 .read = read_oldmem, 837 .open = open_oldmem, 838 }; 839 #endif 840 841 static ssize_t kmsg_write(struct file * file, const char __user * buf, 842 size_t count, loff_t *ppos) 843 { 844 char *tmp; 845 ssize_t ret; 846 847 tmp = kmalloc(count + 1, GFP_KERNEL); 848 if (tmp == NULL) 849 return -ENOMEM; 850 ret = -EFAULT; 851 if (!copy_from_user(tmp, buf, count)) { 852 tmp[count] = 0; 853 ret = printk("%s", tmp); 854 if (ret > count) 855 /* printk can add a prefix */ 856 ret = count; 857 } 858 kfree(tmp); 859 return ret; 860 } 861 862 static const struct file_operations kmsg_fops = { 863 .write = kmsg_write, 864 }; 865 866 static const struct memdev { 867 const char *name; 868 mode_t mode; 869 const struct file_operations *fops; 870 struct backing_dev_info *dev_info; 871 } devlist[] = { 872 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi }, 873 #ifdef CONFIG_DEVKMEM 874 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi }, 875 #endif 876 [3] = { "null", 0666, &null_fops, NULL }, 877 #ifdef CONFIG_DEVPORT 878 [4] = { "port", 0, &port_fops, NULL }, 879 #endif 880 [5] = { "zero", 0666, &zero_fops, &zero_bdi }, 881 [7] = { "full", 0666, &full_fops, NULL }, 882 [8] = { "random", 0666, &random_fops, NULL }, 883 [9] = { "urandom", 0666, &urandom_fops, NULL }, 884 [11] = { "kmsg", 0, &kmsg_fops, NULL }, 885 #ifdef CONFIG_CRASH_DUMP 886 [12] = { "oldmem", 0, &oldmem_fops, NULL }, 887 #endif 888 }; 889 890 static int memory_open(struct inode *inode, struct file *filp) 891 { 892 int minor; 893 const struct memdev *dev; 894 895 minor = iminor(inode); 896 if (minor >= ARRAY_SIZE(devlist)) 897 return -ENXIO; 898 899 dev = &devlist[minor]; 900 if (!dev->fops) 901 return -ENXIO; 902 903 filp->f_op = dev->fops; 904 if (dev->dev_info) 905 filp->f_mapping->backing_dev_info = dev->dev_info; 906 907 if (dev->fops->open) 908 return dev->fops->open(inode, filp); 909 910 return 0; 911 } 912 913 static const struct file_operations memory_fops = { 914 .open = memory_open, 915 }; 916 917 static char *mem_devnode(struct device *dev, mode_t *mode) 918 { 919 if (mode && devlist[MINOR(dev->devt)].mode) 920 *mode = devlist[MINOR(dev->devt)].mode; 921 return NULL; 922 } 923 924 static struct class *mem_class; 925 926 static int __init chr_dev_init(void) 927 { 928 int minor; 929 int err; 930 931 err = bdi_init(&zero_bdi); 932 if (err) 933 return err; 934 935 if (register_chrdev(MEM_MAJOR,"mem",&memory_fops)) 936 printk("unable to get major %d for memory devs\n", MEM_MAJOR); 937 938 mem_class = class_create(THIS_MODULE, "mem"); 939 mem_class->devnode = mem_devnode; 940 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { 941 if (!devlist[minor].name) 942 continue; 943 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), 944 NULL, devlist[minor].name); 945 } 946 947 return 0; 948 } 949 950 fs_initcall(chr_dev_init); 951