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