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 mmaping 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_SYNC 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_SYNC will be done non-cached. 60 */ 61 if (file->f_flags & O_SYNC) 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_NONPROMISC_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 void __attribute__((weak)) 304 map_devmem(unsigned long pfn, unsigned long len, pgprot_t prot) 305 { 306 /* nothing. architectures can override. */ 307 } 308 309 void __attribute__((weak)) 310 unmap_devmem(unsigned long pfn, unsigned long len, pgprot_t prot) 311 { 312 /* nothing. architectures can override. */ 313 } 314 315 static void mmap_mem_open(struct vm_area_struct *vma) 316 { 317 map_devmem(vma->vm_pgoff, vma->vm_end - vma->vm_start, 318 vma->vm_page_prot); 319 } 320 321 static void mmap_mem_close(struct vm_area_struct *vma) 322 { 323 unmap_devmem(vma->vm_pgoff, vma->vm_end - vma->vm_start, 324 vma->vm_page_prot); 325 } 326 327 static struct vm_operations_struct mmap_mem_ops = { 328 .open = mmap_mem_open, 329 .close = mmap_mem_close 330 }; 331 332 static int mmap_mem(struct file * file, struct vm_area_struct * vma) 333 { 334 size_t size = vma->vm_end - vma->vm_start; 335 336 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) 337 return -EINVAL; 338 339 if (!private_mapping_ok(vma)) 340 return -ENOSYS; 341 342 if (!range_is_allowed(vma->vm_pgoff, size)) 343 return -EPERM; 344 345 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, 346 &vma->vm_page_prot)) 347 return -EINVAL; 348 349 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, 350 size, 351 vma->vm_page_prot); 352 353 vma->vm_ops = &mmap_mem_ops; 354 355 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */ 356 if (remap_pfn_range(vma, 357 vma->vm_start, 358 vma->vm_pgoff, 359 size, 360 vma->vm_page_prot)) { 361 unmap_devmem(vma->vm_pgoff, size, vma->vm_page_prot); 362 return -EAGAIN; 363 } 364 return 0; 365 } 366 367 #ifdef CONFIG_DEVKMEM 368 static int mmap_kmem(struct file * file, struct vm_area_struct * vma) 369 { 370 unsigned long pfn; 371 372 /* Turn a kernel-virtual address into a physical page frame */ 373 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; 374 375 /* 376 * RED-PEN: on some architectures there is more mapped memory 377 * than available in mem_map which pfn_valid checks 378 * for. Perhaps should add a new macro here. 379 * 380 * RED-PEN: vmalloc is not supported right now. 381 */ 382 if (!pfn_valid(pfn)) 383 return -EIO; 384 385 vma->vm_pgoff = pfn; 386 return mmap_mem(file, vma); 387 } 388 #endif 389 390 #ifdef CONFIG_CRASH_DUMP 391 /* 392 * Read memory corresponding to the old kernel. 393 */ 394 static ssize_t read_oldmem(struct file *file, char __user *buf, 395 size_t count, loff_t *ppos) 396 { 397 unsigned long pfn, offset; 398 size_t read = 0, csize; 399 int rc = 0; 400 401 while (count) { 402 pfn = *ppos / PAGE_SIZE; 403 if (pfn > saved_max_pfn) 404 return read; 405 406 offset = (unsigned long)(*ppos % PAGE_SIZE); 407 if (count > PAGE_SIZE - offset) 408 csize = PAGE_SIZE - offset; 409 else 410 csize = count; 411 412 rc = copy_oldmem_page(pfn, buf, csize, offset, 1); 413 if (rc < 0) 414 return rc; 415 buf += csize; 416 *ppos += csize; 417 read += csize; 418 count -= csize; 419 } 420 return read; 421 } 422 #endif 423 424 extern long vread(char *buf, char *addr, unsigned long count); 425 extern long vwrite(char *buf, char *addr, unsigned long count); 426 427 #ifdef CONFIG_DEVKMEM 428 /* 429 * This function reads the *virtual* memory as seen by the kernel. 430 */ 431 static ssize_t read_kmem(struct file *file, char __user *buf, 432 size_t count, loff_t *ppos) 433 { 434 unsigned long p = *ppos; 435 ssize_t low_count, read, sz; 436 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ 437 438 read = 0; 439 if (p < (unsigned long) high_memory) { 440 low_count = count; 441 if (count > (unsigned long) high_memory - p) 442 low_count = (unsigned long) high_memory - p; 443 444 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 445 /* we don't have page 0 mapped on sparc and m68k.. */ 446 if (p < PAGE_SIZE && low_count > 0) { 447 size_t tmp = PAGE_SIZE - p; 448 if (tmp > low_count) tmp = low_count; 449 if (clear_user(buf, tmp)) 450 return -EFAULT; 451 buf += tmp; 452 p += tmp; 453 read += tmp; 454 low_count -= tmp; 455 count -= tmp; 456 } 457 #endif 458 while (low_count > 0) { 459 /* 460 * Handle first page in case it's not aligned 461 */ 462 if (-p & (PAGE_SIZE - 1)) 463 sz = -p & (PAGE_SIZE - 1); 464 else 465 sz = PAGE_SIZE; 466 467 sz = min_t(unsigned long, sz, low_count); 468 469 /* 470 * On ia64 if a page has been mapped somewhere as 471 * uncached, then it must also be accessed uncached 472 * by the kernel or data corruption may occur 473 */ 474 kbuf = xlate_dev_kmem_ptr((char *)p); 475 476 if (copy_to_user(buf, kbuf, sz)) 477 return -EFAULT; 478 buf += sz; 479 p += sz; 480 read += sz; 481 low_count -= sz; 482 count -= sz; 483 } 484 } 485 486 if (count > 0) { 487 kbuf = (char *)__get_free_page(GFP_KERNEL); 488 if (!kbuf) 489 return -ENOMEM; 490 while (count > 0) { 491 int len = count; 492 493 if (len > PAGE_SIZE) 494 len = PAGE_SIZE; 495 len = vread(kbuf, (char *)p, len); 496 if (!len) 497 break; 498 if (copy_to_user(buf, kbuf, len)) { 499 free_page((unsigned long)kbuf); 500 return -EFAULT; 501 } 502 count -= len; 503 buf += len; 504 read += len; 505 p += len; 506 } 507 free_page((unsigned long)kbuf); 508 } 509 *ppos = p; 510 return read; 511 } 512 513 514 static inline ssize_t 515 do_write_kmem(void *p, unsigned long realp, const char __user * buf, 516 size_t count, loff_t *ppos) 517 { 518 ssize_t written, sz; 519 unsigned long copied; 520 521 written = 0; 522 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 523 /* we don't have page 0 mapped on sparc and m68k.. */ 524 if (realp < PAGE_SIZE) { 525 unsigned long sz = PAGE_SIZE - realp; 526 if (sz > count) 527 sz = count; 528 /* Hmm. Do something? */ 529 buf += sz; 530 p += sz; 531 realp += sz; 532 count -= sz; 533 written += sz; 534 } 535 #endif 536 537 while (count > 0) { 538 char *ptr; 539 /* 540 * Handle first page in case it's not aligned 541 */ 542 if (-realp & (PAGE_SIZE - 1)) 543 sz = -realp & (PAGE_SIZE - 1); 544 else 545 sz = PAGE_SIZE; 546 547 sz = min_t(unsigned long, sz, count); 548 549 /* 550 * On ia64 if a page has been mapped somewhere as 551 * uncached, then it must also be accessed uncached 552 * by the kernel or data corruption may occur 553 */ 554 ptr = xlate_dev_kmem_ptr(p); 555 556 copied = copy_from_user(ptr, buf, sz); 557 if (copied) { 558 written += sz - copied; 559 if (written) 560 break; 561 return -EFAULT; 562 } 563 buf += sz; 564 p += sz; 565 realp += sz; 566 count -= sz; 567 written += sz; 568 } 569 570 *ppos += written; 571 return written; 572 } 573 574 575 /* 576 * This function writes to the *virtual* memory as seen by the kernel. 577 */ 578 static ssize_t write_kmem(struct file * file, const char __user * buf, 579 size_t count, loff_t *ppos) 580 { 581 unsigned long p = *ppos; 582 ssize_t wrote = 0; 583 ssize_t virtr = 0; 584 ssize_t written; 585 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 586 587 if (p < (unsigned long) high_memory) { 588 589 wrote = count; 590 if (count > (unsigned long) high_memory - p) 591 wrote = (unsigned long) high_memory - p; 592 593 written = do_write_kmem((void*)p, p, buf, wrote, ppos); 594 if (written != wrote) 595 return written; 596 wrote = written; 597 p += wrote; 598 buf += wrote; 599 count -= wrote; 600 } 601 602 if (count > 0) { 603 kbuf = (char *)__get_free_page(GFP_KERNEL); 604 if (!kbuf) 605 return wrote ? wrote : -ENOMEM; 606 while (count > 0) { 607 int len = count; 608 609 if (len > PAGE_SIZE) 610 len = PAGE_SIZE; 611 if (len) { 612 written = copy_from_user(kbuf, buf, len); 613 if (written) { 614 if (wrote + virtr) 615 break; 616 free_page((unsigned long)kbuf); 617 return -EFAULT; 618 } 619 } 620 len = vwrite(kbuf, (char *)p, len); 621 count -= len; 622 buf += len; 623 virtr += len; 624 p += len; 625 } 626 free_page((unsigned long)kbuf); 627 } 628 629 *ppos = p; 630 return virtr + wrote; 631 } 632 #endif 633 634 #ifdef CONFIG_DEVPORT 635 static ssize_t read_port(struct file * file, char __user * buf, 636 size_t count, loff_t *ppos) 637 { 638 unsigned long i = *ppos; 639 char __user *tmp = buf; 640 641 if (!access_ok(VERIFY_WRITE, buf, count)) 642 return -EFAULT; 643 while (count-- > 0 && i < 65536) { 644 if (__put_user(inb(i),tmp) < 0) 645 return -EFAULT; 646 i++; 647 tmp++; 648 } 649 *ppos = i; 650 return tmp-buf; 651 } 652 653 static ssize_t write_port(struct file * file, const char __user * buf, 654 size_t count, loff_t *ppos) 655 { 656 unsigned long i = *ppos; 657 const char __user * tmp = buf; 658 659 if (!access_ok(VERIFY_READ,buf,count)) 660 return -EFAULT; 661 while (count-- > 0 && i < 65536) { 662 char c; 663 if (__get_user(c, tmp)) { 664 if (tmp > buf) 665 break; 666 return -EFAULT; 667 } 668 outb(c,i); 669 i++; 670 tmp++; 671 } 672 *ppos = i; 673 return tmp-buf; 674 } 675 #endif 676 677 static ssize_t read_null(struct file * file, char __user * buf, 678 size_t count, loff_t *ppos) 679 { 680 return 0; 681 } 682 683 static ssize_t write_null(struct file * file, const char __user * buf, 684 size_t count, loff_t *ppos) 685 { 686 return count; 687 } 688 689 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, 690 struct splice_desc *sd) 691 { 692 return sd->len; 693 } 694 695 static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out, 696 loff_t *ppos, size_t len, unsigned int flags) 697 { 698 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); 699 } 700 701 static ssize_t read_zero(struct file * file, char __user * buf, 702 size_t count, loff_t *ppos) 703 { 704 size_t written; 705 706 if (!count) 707 return 0; 708 709 if (!access_ok(VERIFY_WRITE, buf, count)) 710 return -EFAULT; 711 712 written = 0; 713 while (count) { 714 unsigned long unwritten; 715 size_t chunk = count; 716 717 if (chunk > PAGE_SIZE) 718 chunk = PAGE_SIZE; /* Just for latency reasons */ 719 unwritten = clear_user(buf, chunk); 720 written += chunk - unwritten; 721 if (unwritten) 722 break; 723 buf += chunk; 724 count -= chunk; 725 cond_resched(); 726 } 727 return written ? written : -EFAULT; 728 } 729 730 static int mmap_zero(struct file * file, struct vm_area_struct * vma) 731 { 732 #ifndef CONFIG_MMU 733 return -ENOSYS; 734 #endif 735 if (vma->vm_flags & VM_SHARED) 736 return shmem_zero_setup(vma); 737 return 0; 738 } 739 740 static ssize_t write_full(struct file * file, const char __user * buf, 741 size_t count, loff_t *ppos) 742 { 743 return -ENOSPC; 744 } 745 746 /* 747 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 748 * can fopen() both devices with "a" now. This was previously impossible. 749 * -- SRB. 750 */ 751 752 static loff_t null_lseek(struct file * file, loff_t offset, int orig) 753 { 754 return file->f_pos = 0; 755 } 756 757 /* 758 * The memory devices use the full 32/64 bits of the offset, and so we cannot 759 * check against negative addresses: they are ok. The return value is weird, 760 * though, in that case (0). 761 * 762 * also note that seeking relative to the "end of file" isn't supported: 763 * it has no meaning, so it returns -EINVAL. 764 */ 765 static loff_t memory_lseek(struct file * file, loff_t offset, int orig) 766 { 767 loff_t ret; 768 769 mutex_lock(&file->f_path.dentry->d_inode->i_mutex); 770 switch (orig) { 771 case 0: 772 file->f_pos = offset; 773 ret = file->f_pos; 774 force_successful_syscall_return(); 775 break; 776 case 1: 777 file->f_pos += offset; 778 ret = file->f_pos; 779 force_successful_syscall_return(); 780 break; 781 default: 782 ret = -EINVAL; 783 } 784 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex); 785 return ret; 786 } 787 788 static int open_port(struct inode * inode, struct file * filp) 789 { 790 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 791 } 792 793 #define zero_lseek null_lseek 794 #define full_lseek null_lseek 795 #define write_zero write_null 796 #define read_full read_zero 797 #define open_mem open_port 798 #define open_kmem open_mem 799 #define open_oldmem open_mem 800 801 static const struct file_operations mem_fops = { 802 .llseek = memory_lseek, 803 .read = read_mem, 804 .write = write_mem, 805 .mmap = mmap_mem, 806 .open = open_mem, 807 .get_unmapped_area = get_unmapped_area_mem, 808 }; 809 810 #ifdef CONFIG_DEVKMEM 811 static const struct file_operations kmem_fops = { 812 .llseek = memory_lseek, 813 .read = read_kmem, 814 .write = write_kmem, 815 .mmap = mmap_kmem, 816 .open = open_kmem, 817 .get_unmapped_area = get_unmapped_area_mem, 818 }; 819 #endif 820 821 static const struct file_operations null_fops = { 822 .llseek = null_lseek, 823 .read = read_null, 824 .write = write_null, 825 .splice_write = splice_write_null, 826 }; 827 828 #ifdef CONFIG_DEVPORT 829 static const struct file_operations port_fops = { 830 .llseek = memory_lseek, 831 .read = read_port, 832 .write = write_port, 833 .open = open_port, 834 }; 835 #endif 836 837 static const struct file_operations zero_fops = { 838 .llseek = zero_lseek, 839 .read = read_zero, 840 .write = write_zero, 841 .mmap = mmap_zero, 842 }; 843 844 /* 845 * capabilities for /dev/zero 846 * - permits private mappings, "copies" are taken of the source of zeros 847 */ 848 static struct backing_dev_info zero_bdi = { 849 .capabilities = BDI_CAP_MAP_COPY, 850 }; 851 852 static const struct file_operations full_fops = { 853 .llseek = full_lseek, 854 .read = read_full, 855 .write = write_full, 856 }; 857 858 #ifdef CONFIG_CRASH_DUMP 859 static const struct file_operations oldmem_fops = { 860 .read = read_oldmem, 861 .open = open_oldmem, 862 }; 863 #endif 864 865 static ssize_t kmsg_write(struct file * file, const char __user * buf, 866 size_t count, loff_t *ppos) 867 { 868 char *tmp; 869 ssize_t ret; 870 871 tmp = kmalloc(count + 1, GFP_KERNEL); 872 if (tmp == NULL) 873 return -ENOMEM; 874 ret = -EFAULT; 875 if (!copy_from_user(tmp, buf, count)) { 876 tmp[count] = 0; 877 ret = printk("%s", tmp); 878 if (ret > count) 879 /* printk can add a prefix */ 880 ret = count; 881 } 882 kfree(tmp); 883 return ret; 884 } 885 886 static const struct file_operations kmsg_fops = { 887 .write = kmsg_write, 888 }; 889 890 static int memory_open(struct inode * inode, struct file * filp) 891 { 892 switch (iminor(inode)) { 893 case 1: 894 filp->f_op = &mem_fops; 895 filp->f_mapping->backing_dev_info = 896 &directly_mappable_cdev_bdi; 897 break; 898 #ifdef CONFIG_DEVKMEM 899 case 2: 900 filp->f_op = &kmem_fops; 901 filp->f_mapping->backing_dev_info = 902 &directly_mappable_cdev_bdi; 903 break; 904 #endif 905 case 3: 906 filp->f_op = &null_fops; 907 break; 908 #ifdef CONFIG_DEVPORT 909 case 4: 910 filp->f_op = &port_fops; 911 break; 912 #endif 913 case 5: 914 filp->f_mapping->backing_dev_info = &zero_bdi; 915 filp->f_op = &zero_fops; 916 break; 917 case 7: 918 filp->f_op = &full_fops; 919 break; 920 case 8: 921 filp->f_op = &random_fops; 922 break; 923 case 9: 924 filp->f_op = &urandom_fops; 925 break; 926 case 11: 927 filp->f_op = &kmsg_fops; 928 break; 929 #ifdef CONFIG_CRASH_DUMP 930 case 12: 931 filp->f_op = &oldmem_fops; 932 break; 933 #endif 934 default: 935 return -ENXIO; 936 } 937 if (filp->f_op && filp->f_op->open) 938 return filp->f_op->open(inode,filp); 939 return 0; 940 } 941 942 static const struct file_operations memory_fops = { 943 .open = memory_open, /* just a selector for the real open */ 944 }; 945 946 static const struct { 947 unsigned int minor; 948 char *name; 949 umode_t mode; 950 const struct file_operations *fops; 951 } devlist[] = { /* list of minor devices */ 952 {1, "mem", S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops}, 953 #ifdef CONFIG_DEVKMEM 954 {2, "kmem", S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops}, 955 #endif 956 {3, "null", S_IRUGO | S_IWUGO, &null_fops}, 957 #ifdef CONFIG_DEVPORT 958 {4, "port", S_IRUSR | S_IWUSR | S_IRGRP, &port_fops}, 959 #endif 960 {5, "zero", S_IRUGO | S_IWUGO, &zero_fops}, 961 {7, "full", S_IRUGO | S_IWUGO, &full_fops}, 962 {8, "random", S_IRUGO | S_IWUSR, &random_fops}, 963 {9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops}, 964 {11,"kmsg", S_IRUGO | S_IWUSR, &kmsg_fops}, 965 #ifdef CONFIG_CRASH_DUMP 966 {12,"oldmem", S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops}, 967 #endif 968 }; 969 970 static struct class *mem_class; 971 972 static int __init chr_dev_init(void) 973 { 974 int i; 975 int err; 976 977 err = bdi_init(&zero_bdi); 978 if (err) 979 return err; 980 981 if (register_chrdev(MEM_MAJOR,"mem",&memory_fops)) 982 printk("unable to get major %d for memory devs\n", MEM_MAJOR); 983 984 mem_class = class_create(THIS_MODULE, "mem"); 985 for (i = 0; i < ARRAY_SIZE(devlist); i++) 986 device_create(mem_class, NULL, 987 MKDEV(MEM_MAJOR, devlist[i].minor), 988 devlist[i].name); 989 990 return 0; 991 } 992 993 fs_initcall(chr_dev_init); 994