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/config.h> 12 #include <linux/mm.h> 13 #include <linux/miscdevice.h> 14 #include <linux/slab.h> 15 #include <linux/vmalloc.h> 16 #include <linux/mman.h> 17 #include <linux/random.h> 18 #include <linux/init.h> 19 #include <linux/raw.h> 20 #include <linux/tty.h> 21 #include <linux/capability.h> 22 #include <linux/smp_lock.h> 23 #include <linux/devfs_fs_kernel.h> 24 #include <linux/ptrace.h> 25 #include <linux/device.h> 26 #include <linux/highmem.h> 27 #include <linux/crash_dump.h> 28 #include <linux/backing-dev.h> 29 #include <linux/bootmem.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 /* 39 * Architectures vary in how they handle caching for addresses 40 * outside of main memory. 41 * 42 */ 43 static inline int uncached_access(struct file *file, unsigned long addr) 44 { 45 #if defined(__i386__) 46 /* 47 * On the PPro and successors, the MTRRs are used to set 48 * memory types for physical addresses outside main memory, 49 * so blindly setting PCD or PWT on those pages is wrong. 50 * For Pentiums and earlier, the surround logic should disable 51 * caching for the high addresses through the KEN pin, but 52 * we maintain the tradition of paranoia in this code. 53 */ 54 if (file->f_flags & O_SYNC) 55 return 1; 56 return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) || 57 test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) || 58 test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) || 59 test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) ) 60 && addr >= __pa(high_memory); 61 #elif defined(__x86_64__) 62 /* 63 * This is broken because it can generate memory type aliases, 64 * which can cause cache corruptions 65 * But it is only available for root and we have to be bug-to-bug 66 * compatible with i386. 67 */ 68 if (file->f_flags & O_SYNC) 69 return 1; 70 /* same behaviour as i386. PAT always set to cached and MTRRs control the 71 caching behaviour. 72 Hopefully a full PAT implementation will fix that soon. */ 73 return 0; 74 #elif defined(CONFIG_IA64) 75 /* 76 * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases. 77 */ 78 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB); 79 #else 80 /* 81 * Accessing memory above the top the kernel knows about or through a file pointer 82 * that was marked O_SYNC will be done non-cached. 83 */ 84 if (file->f_flags & O_SYNC) 85 return 1; 86 return addr >= __pa(high_memory); 87 #endif 88 } 89 90 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE 91 static inline int valid_phys_addr_range(unsigned long addr, size_t *count) 92 { 93 unsigned long end_mem; 94 95 end_mem = __pa(high_memory); 96 if (addr >= end_mem) 97 return 0; 98 99 if (*count > end_mem - addr) 100 *count = end_mem - addr; 101 102 return 1; 103 } 104 #endif 105 106 /* 107 * This funcion reads the *physical* memory. The f_pos points directly to the 108 * memory location. 109 */ 110 static ssize_t read_mem(struct file * file, char __user * buf, 111 size_t count, loff_t *ppos) 112 { 113 unsigned long p = *ppos; 114 ssize_t read, sz; 115 char *ptr; 116 117 if (!valid_phys_addr_range(p, &count)) 118 return -EFAULT; 119 read = 0; 120 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 121 /* we don't have page 0 mapped on sparc and m68k.. */ 122 if (p < PAGE_SIZE) { 123 sz = PAGE_SIZE - p; 124 if (sz > count) 125 sz = count; 126 if (sz > 0) { 127 if (clear_user(buf, sz)) 128 return -EFAULT; 129 buf += sz; 130 p += sz; 131 count -= sz; 132 read += sz; 133 } 134 } 135 #endif 136 137 while (count > 0) { 138 /* 139 * Handle first page in case it's not aligned 140 */ 141 if (-p & (PAGE_SIZE - 1)) 142 sz = -p & (PAGE_SIZE - 1); 143 else 144 sz = PAGE_SIZE; 145 146 sz = min_t(unsigned long, sz, count); 147 148 /* 149 * On ia64 if a page has been mapped somewhere as 150 * uncached, then it must also be accessed uncached 151 * by the kernel or data corruption may occur 152 */ 153 ptr = xlate_dev_mem_ptr(p); 154 155 if (copy_to_user(buf, ptr, sz)) 156 return -EFAULT; 157 buf += sz; 158 p += sz; 159 count -= sz; 160 read += sz; 161 } 162 163 *ppos += read; 164 return read; 165 } 166 167 static ssize_t write_mem(struct file * file, const char __user * buf, 168 size_t count, loff_t *ppos) 169 { 170 unsigned long p = *ppos; 171 ssize_t written, sz; 172 unsigned long copied; 173 void *ptr; 174 175 if (!valid_phys_addr_range(p, &count)) 176 return -EFAULT; 177 178 written = 0; 179 180 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 181 /* we don't have page 0 mapped on sparc and m68k.. */ 182 if (p < PAGE_SIZE) { 183 unsigned long sz = PAGE_SIZE - p; 184 if (sz > count) 185 sz = count; 186 /* Hmm. Do something? */ 187 buf += sz; 188 p += sz; 189 count -= sz; 190 written += sz; 191 } 192 #endif 193 194 while (count > 0) { 195 /* 196 * Handle first page in case it's not aligned 197 */ 198 if (-p & (PAGE_SIZE - 1)) 199 sz = -p & (PAGE_SIZE - 1); 200 else 201 sz = PAGE_SIZE; 202 203 sz = min_t(unsigned long, sz, count); 204 205 /* 206 * On ia64 if a page has been mapped somewhere as 207 * uncached, then it must also be accessed uncached 208 * by the kernel or data corruption may occur 209 */ 210 ptr = xlate_dev_mem_ptr(p); 211 212 copied = copy_from_user(ptr, buf, sz); 213 if (copied) { 214 ssize_t ret; 215 216 ret = written + (sz - copied); 217 if (ret) 218 return ret; 219 return -EFAULT; 220 } 221 buf += sz; 222 p += sz; 223 count -= sz; 224 written += sz; 225 } 226 227 *ppos += written; 228 return written; 229 } 230 231 static int mmap_mem(struct file * file, struct vm_area_struct * vma) 232 { 233 #if defined(__HAVE_PHYS_MEM_ACCESS_PROT) 234 unsigned long offset = vma->vm_pgoff << PAGE_SHIFT; 235 236 vma->vm_page_prot = phys_mem_access_prot(file, offset, 237 vma->vm_end - vma->vm_start, 238 vma->vm_page_prot); 239 #elif defined(pgprot_noncached) 240 unsigned long offset = vma->vm_pgoff << PAGE_SHIFT; 241 int uncached; 242 243 uncached = uncached_access(file, offset); 244 if (uncached) 245 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 246 #endif 247 248 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */ 249 if (remap_pfn_range(vma, 250 vma->vm_start, 251 vma->vm_pgoff, 252 vma->vm_end-vma->vm_start, 253 vma->vm_page_prot)) 254 return -EAGAIN; 255 return 0; 256 } 257 258 static int mmap_kmem(struct file * file, struct vm_area_struct * vma) 259 { 260 unsigned long pfn; 261 262 /* Turn a kernel-virtual address into a physical page frame */ 263 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; 264 265 /* 266 * RED-PEN: on some architectures there is more mapped memory 267 * than available in mem_map which pfn_valid checks 268 * for. Perhaps should add a new macro here. 269 * 270 * RED-PEN: vmalloc is not supported right now. 271 */ 272 if (!pfn_valid(pfn)) 273 return -EIO; 274 275 vma->vm_pgoff = pfn; 276 return mmap_mem(file, vma); 277 } 278 279 #ifdef CONFIG_CRASH_DUMP 280 /* 281 * Read memory corresponding to the old kernel. 282 */ 283 static ssize_t read_oldmem(struct file *file, char __user *buf, 284 size_t count, loff_t *ppos) 285 { 286 unsigned long pfn, offset; 287 size_t read = 0, csize; 288 int rc = 0; 289 290 while (count) { 291 pfn = *ppos / PAGE_SIZE; 292 if (pfn > saved_max_pfn) 293 return read; 294 295 offset = (unsigned long)(*ppos % PAGE_SIZE); 296 if (count > PAGE_SIZE - offset) 297 csize = PAGE_SIZE - offset; 298 else 299 csize = count; 300 301 rc = copy_oldmem_page(pfn, buf, csize, offset, 1); 302 if (rc < 0) 303 return rc; 304 buf += csize; 305 *ppos += csize; 306 read += csize; 307 count -= csize; 308 } 309 return read; 310 } 311 #endif 312 313 extern long vread(char *buf, char *addr, unsigned long count); 314 extern long vwrite(char *buf, char *addr, unsigned long count); 315 316 /* 317 * This function reads the *virtual* memory as seen by the kernel. 318 */ 319 static ssize_t read_kmem(struct file *file, char __user *buf, 320 size_t count, loff_t *ppos) 321 { 322 unsigned long p = *ppos; 323 ssize_t low_count, read, sz; 324 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ 325 326 read = 0; 327 if (p < (unsigned long) high_memory) { 328 low_count = count; 329 if (count > (unsigned long) high_memory - p) 330 low_count = (unsigned long) high_memory - p; 331 332 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 333 /* we don't have page 0 mapped on sparc and m68k.. */ 334 if (p < PAGE_SIZE && low_count > 0) { 335 size_t tmp = PAGE_SIZE - p; 336 if (tmp > low_count) tmp = low_count; 337 if (clear_user(buf, tmp)) 338 return -EFAULT; 339 buf += tmp; 340 p += tmp; 341 read += tmp; 342 low_count -= tmp; 343 count -= tmp; 344 } 345 #endif 346 while (low_count > 0) { 347 /* 348 * Handle first page in case it's not aligned 349 */ 350 if (-p & (PAGE_SIZE - 1)) 351 sz = -p & (PAGE_SIZE - 1); 352 else 353 sz = PAGE_SIZE; 354 355 sz = min_t(unsigned long, sz, low_count); 356 357 /* 358 * On ia64 if a page has been mapped somewhere as 359 * uncached, then it must also be accessed uncached 360 * by the kernel or data corruption may occur 361 */ 362 kbuf = xlate_dev_kmem_ptr((char *)p); 363 364 if (copy_to_user(buf, kbuf, sz)) 365 return -EFAULT; 366 buf += sz; 367 p += sz; 368 read += sz; 369 low_count -= sz; 370 count -= sz; 371 } 372 } 373 374 if (count > 0) { 375 kbuf = (char *)__get_free_page(GFP_KERNEL); 376 if (!kbuf) 377 return -ENOMEM; 378 while (count > 0) { 379 int len = count; 380 381 if (len > PAGE_SIZE) 382 len = PAGE_SIZE; 383 len = vread(kbuf, (char *)p, len); 384 if (!len) 385 break; 386 if (copy_to_user(buf, kbuf, len)) { 387 free_page((unsigned long)kbuf); 388 return -EFAULT; 389 } 390 count -= len; 391 buf += len; 392 read += len; 393 p += len; 394 } 395 free_page((unsigned long)kbuf); 396 } 397 *ppos = p; 398 return read; 399 } 400 401 402 static inline ssize_t 403 do_write_kmem(void *p, unsigned long realp, const char __user * buf, 404 size_t count, loff_t *ppos) 405 { 406 ssize_t written, sz; 407 unsigned long copied; 408 409 written = 0; 410 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 411 /* we don't have page 0 mapped on sparc and m68k.. */ 412 if (realp < PAGE_SIZE) { 413 unsigned long sz = PAGE_SIZE - realp; 414 if (sz > count) 415 sz = count; 416 /* Hmm. Do something? */ 417 buf += sz; 418 p += sz; 419 realp += sz; 420 count -= sz; 421 written += sz; 422 } 423 #endif 424 425 while (count > 0) { 426 char *ptr; 427 /* 428 * Handle first page in case it's not aligned 429 */ 430 if (-realp & (PAGE_SIZE - 1)) 431 sz = -realp & (PAGE_SIZE - 1); 432 else 433 sz = PAGE_SIZE; 434 435 sz = min_t(unsigned long, sz, count); 436 437 /* 438 * On ia64 if a page has been mapped somewhere as 439 * uncached, then it must also be accessed uncached 440 * by the kernel or data corruption may occur 441 */ 442 ptr = xlate_dev_kmem_ptr(p); 443 444 copied = copy_from_user(ptr, buf, sz); 445 if (copied) { 446 ssize_t ret; 447 448 ret = written + (sz - copied); 449 if (ret) 450 return ret; 451 return -EFAULT; 452 } 453 buf += sz; 454 p += sz; 455 realp += sz; 456 count -= sz; 457 written += sz; 458 } 459 460 *ppos += written; 461 return written; 462 } 463 464 465 /* 466 * This function writes to the *virtual* memory as seen by the kernel. 467 */ 468 static ssize_t write_kmem(struct file * file, const char __user * buf, 469 size_t count, loff_t *ppos) 470 { 471 unsigned long p = *ppos; 472 ssize_t wrote = 0; 473 ssize_t virtr = 0; 474 ssize_t written; 475 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 476 477 if (p < (unsigned long) high_memory) { 478 479 wrote = count; 480 if (count > (unsigned long) high_memory - p) 481 wrote = (unsigned long) high_memory - p; 482 483 written = do_write_kmem((void*)p, p, buf, wrote, ppos); 484 if (written != wrote) 485 return written; 486 wrote = written; 487 p += wrote; 488 buf += wrote; 489 count -= wrote; 490 } 491 492 if (count > 0) { 493 kbuf = (char *)__get_free_page(GFP_KERNEL); 494 if (!kbuf) 495 return wrote ? wrote : -ENOMEM; 496 while (count > 0) { 497 int len = count; 498 499 if (len > PAGE_SIZE) 500 len = PAGE_SIZE; 501 if (len) { 502 written = copy_from_user(kbuf, buf, len); 503 if (written) { 504 ssize_t ret; 505 506 free_page((unsigned long)kbuf); 507 ret = wrote + virtr + (len - written); 508 return ret ? ret : -EFAULT; 509 } 510 } 511 len = vwrite(kbuf, (char *)p, len); 512 count -= len; 513 buf += len; 514 virtr += len; 515 p += len; 516 } 517 free_page((unsigned long)kbuf); 518 } 519 520 *ppos = p; 521 return virtr + wrote; 522 } 523 524 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI)) 525 static ssize_t read_port(struct file * file, char __user * buf, 526 size_t count, loff_t *ppos) 527 { 528 unsigned long i = *ppos; 529 char __user *tmp = buf; 530 531 if (!access_ok(VERIFY_WRITE, buf, count)) 532 return -EFAULT; 533 while (count-- > 0 && i < 65536) { 534 if (__put_user(inb(i),tmp) < 0) 535 return -EFAULT; 536 i++; 537 tmp++; 538 } 539 *ppos = i; 540 return tmp-buf; 541 } 542 543 static ssize_t write_port(struct file * file, const char __user * buf, 544 size_t count, loff_t *ppos) 545 { 546 unsigned long i = *ppos; 547 const char __user * tmp = buf; 548 549 if (!access_ok(VERIFY_READ,buf,count)) 550 return -EFAULT; 551 while (count-- > 0 && i < 65536) { 552 char c; 553 if (__get_user(c, tmp)) 554 return -EFAULT; 555 outb(c,i); 556 i++; 557 tmp++; 558 } 559 *ppos = i; 560 return tmp-buf; 561 } 562 #endif 563 564 static ssize_t read_null(struct file * file, char __user * buf, 565 size_t count, loff_t *ppos) 566 { 567 return 0; 568 } 569 570 static ssize_t write_null(struct file * file, const char __user * buf, 571 size_t count, loff_t *ppos) 572 { 573 return count; 574 } 575 576 #ifdef CONFIG_MMU 577 /* 578 * For fun, we are using the MMU for this. 579 */ 580 static inline size_t read_zero_pagealigned(char __user * buf, size_t size) 581 { 582 struct mm_struct *mm; 583 struct vm_area_struct * vma; 584 unsigned long addr=(unsigned long)buf; 585 586 mm = current->mm; 587 /* Oops, this was forgotten before. -ben */ 588 down_read(&mm->mmap_sem); 589 590 /* For private mappings, just map in zero pages. */ 591 for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) { 592 unsigned long count; 593 594 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0) 595 goto out_up; 596 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB)) 597 break; 598 count = vma->vm_end - addr; 599 if (count > size) 600 count = size; 601 602 zap_page_range(vma, addr, count, NULL); 603 zeromap_page_range(vma, addr, count, PAGE_COPY); 604 605 size -= count; 606 buf += count; 607 addr += count; 608 if (size == 0) 609 goto out_up; 610 } 611 612 up_read(&mm->mmap_sem); 613 614 /* The shared case is hard. Let's do the conventional zeroing. */ 615 do { 616 unsigned long unwritten = clear_user(buf, PAGE_SIZE); 617 if (unwritten) 618 return size + unwritten - PAGE_SIZE; 619 cond_resched(); 620 buf += PAGE_SIZE; 621 size -= PAGE_SIZE; 622 } while (size); 623 624 return size; 625 out_up: 626 up_read(&mm->mmap_sem); 627 return size; 628 } 629 630 static ssize_t read_zero(struct file * file, char __user * buf, 631 size_t count, loff_t *ppos) 632 { 633 unsigned long left, unwritten, written = 0; 634 635 if (!count) 636 return 0; 637 638 if (!access_ok(VERIFY_WRITE, buf, count)) 639 return -EFAULT; 640 641 left = count; 642 643 /* do we want to be clever? Arbitrary cut-off */ 644 if (count >= PAGE_SIZE*4) { 645 unsigned long partial; 646 647 /* How much left of the page? */ 648 partial = (PAGE_SIZE-1) & -(unsigned long) buf; 649 unwritten = clear_user(buf, partial); 650 written = partial - unwritten; 651 if (unwritten) 652 goto out; 653 left -= partial; 654 buf += partial; 655 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK); 656 written += (left & PAGE_MASK) - unwritten; 657 if (unwritten) 658 goto out; 659 buf += left & PAGE_MASK; 660 left &= ~PAGE_MASK; 661 } 662 unwritten = clear_user(buf, left); 663 written += left - unwritten; 664 out: 665 return written ? written : -EFAULT; 666 } 667 668 static int mmap_zero(struct file * file, struct vm_area_struct * vma) 669 { 670 if (vma->vm_flags & VM_SHARED) 671 return shmem_zero_setup(vma); 672 if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot)) 673 return -EAGAIN; 674 return 0; 675 } 676 #else /* CONFIG_MMU */ 677 static ssize_t read_zero(struct file * file, char * buf, 678 size_t count, loff_t *ppos) 679 { 680 size_t todo = count; 681 682 while (todo) { 683 size_t chunk = todo; 684 685 if (chunk > 4096) 686 chunk = 4096; /* Just for latency reasons */ 687 if (clear_user(buf, chunk)) 688 return -EFAULT; 689 buf += chunk; 690 todo -= chunk; 691 cond_resched(); 692 } 693 return count; 694 } 695 696 static int mmap_zero(struct file * file, struct vm_area_struct * vma) 697 { 698 return -ENOSYS; 699 } 700 #endif /* CONFIG_MMU */ 701 702 static ssize_t write_full(struct file * file, const char __user * buf, 703 size_t count, loff_t *ppos) 704 { 705 return -ENOSPC; 706 } 707 708 /* 709 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 710 * can fopen() both devices with "a" now. This was previously impossible. 711 * -- SRB. 712 */ 713 714 static loff_t null_lseek(struct file * file, loff_t offset, int orig) 715 { 716 return file->f_pos = 0; 717 } 718 719 /* 720 * The memory devices use the full 32/64 bits of the offset, and so we cannot 721 * check against negative addresses: they are ok. The return value is weird, 722 * though, in that case (0). 723 * 724 * also note that seeking relative to the "end of file" isn't supported: 725 * it has no meaning, so it returns -EINVAL. 726 */ 727 static loff_t memory_lseek(struct file * file, loff_t offset, int orig) 728 { 729 loff_t ret; 730 731 down(&file->f_dentry->d_inode->i_sem); 732 switch (orig) { 733 case 0: 734 file->f_pos = offset; 735 ret = file->f_pos; 736 force_successful_syscall_return(); 737 break; 738 case 1: 739 file->f_pos += offset; 740 ret = file->f_pos; 741 force_successful_syscall_return(); 742 break; 743 default: 744 ret = -EINVAL; 745 } 746 up(&file->f_dentry->d_inode->i_sem); 747 return ret; 748 } 749 750 static int open_port(struct inode * inode, struct file * filp) 751 { 752 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 753 } 754 755 #define zero_lseek null_lseek 756 #define full_lseek null_lseek 757 #define write_zero write_null 758 #define read_full read_zero 759 #define open_mem open_port 760 #define open_kmem open_mem 761 #define open_oldmem open_mem 762 763 static struct file_operations mem_fops = { 764 .llseek = memory_lseek, 765 .read = read_mem, 766 .write = write_mem, 767 .mmap = mmap_mem, 768 .open = open_mem, 769 }; 770 771 static struct file_operations kmem_fops = { 772 .llseek = memory_lseek, 773 .read = read_kmem, 774 .write = write_kmem, 775 .mmap = mmap_kmem, 776 .open = open_kmem, 777 }; 778 779 static struct file_operations null_fops = { 780 .llseek = null_lseek, 781 .read = read_null, 782 .write = write_null, 783 }; 784 785 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI)) 786 static struct file_operations port_fops = { 787 .llseek = memory_lseek, 788 .read = read_port, 789 .write = write_port, 790 .open = open_port, 791 }; 792 #endif 793 794 static struct file_operations zero_fops = { 795 .llseek = zero_lseek, 796 .read = read_zero, 797 .write = write_zero, 798 .mmap = mmap_zero, 799 }; 800 801 static struct backing_dev_info zero_bdi = { 802 .capabilities = BDI_CAP_MAP_COPY, 803 }; 804 805 static struct file_operations full_fops = { 806 .llseek = full_lseek, 807 .read = read_full, 808 .write = write_full, 809 }; 810 811 #ifdef CONFIG_CRASH_DUMP 812 static struct file_operations oldmem_fops = { 813 .read = read_oldmem, 814 .open = open_oldmem, 815 }; 816 #endif 817 818 static ssize_t kmsg_write(struct file * file, const char __user * buf, 819 size_t count, loff_t *ppos) 820 { 821 char *tmp; 822 int ret; 823 824 tmp = kmalloc(count + 1, GFP_KERNEL); 825 if (tmp == NULL) 826 return -ENOMEM; 827 ret = -EFAULT; 828 if (!copy_from_user(tmp, buf, count)) { 829 tmp[count] = 0; 830 ret = printk("%s", tmp); 831 } 832 kfree(tmp); 833 return ret; 834 } 835 836 static struct file_operations kmsg_fops = { 837 .write = kmsg_write, 838 }; 839 840 static int memory_open(struct inode * inode, struct file * filp) 841 { 842 switch (iminor(inode)) { 843 case 1: 844 filp->f_op = &mem_fops; 845 break; 846 case 2: 847 filp->f_op = &kmem_fops; 848 break; 849 case 3: 850 filp->f_op = &null_fops; 851 break; 852 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI)) 853 case 4: 854 filp->f_op = &port_fops; 855 break; 856 #endif 857 case 5: 858 filp->f_mapping->backing_dev_info = &zero_bdi; 859 filp->f_op = &zero_fops; 860 break; 861 case 7: 862 filp->f_op = &full_fops; 863 break; 864 case 8: 865 filp->f_op = &random_fops; 866 break; 867 case 9: 868 filp->f_op = &urandom_fops; 869 break; 870 case 11: 871 filp->f_op = &kmsg_fops; 872 break; 873 #ifdef CONFIG_CRASH_DUMP 874 case 12: 875 filp->f_op = &oldmem_fops; 876 break; 877 #endif 878 default: 879 return -ENXIO; 880 } 881 if (filp->f_op && filp->f_op->open) 882 return filp->f_op->open(inode,filp); 883 return 0; 884 } 885 886 static struct file_operations memory_fops = { 887 .open = memory_open, /* just a selector for the real open */ 888 }; 889 890 static const struct { 891 unsigned int minor; 892 char *name; 893 umode_t mode; 894 struct file_operations *fops; 895 } devlist[] = { /* list of minor devices */ 896 {1, "mem", S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops}, 897 {2, "kmem", S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops}, 898 {3, "null", S_IRUGO | S_IWUGO, &null_fops}, 899 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI)) 900 {4, "port", S_IRUSR | S_IWUSR | S_IRGRP, &port_fops}, 901 #endif 902 {5, "zero", S_IRUGO | S_IWUGO, &zero_fops}, 903 {7, "full", S_IRUGO | S_IWUGO, &full_fops}, 904 {8, "random", S_IRUGO | S_IWUSR, &random_fops}, 905 {9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops}, 906 {11,"kmsg", S_IRUGO | S_IWUSR, &kmsg_fops}, 907 #ifdef CONFIG_CRASH_DUMP 908 {12,"oldmem", S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops}, 909 #endif 910 }; 911 912 static struct class *mem_class; 913 914 static int __init chr_dev_init(void) 915 { 916 int i; 917 918 if (register_chrdev(MEM_MAJOR,"mem",&memory_fops)) 919 printk("unable to get major %d for memory devs\n", MEM_MAJOR); 920 921 mem_class = class_create(THIS_MODULE, "mem"); 922 for (i = 0; i < ARRAY_SIZE(devlist); i++) { 923 class_device_create(mem_class, MKDEV(MEM_MAJOR, devlist[i].minor), 924 NULL, devlist[i].name); 925 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor), 926 S_IFCHR | devlist[i].mode, devlist[i].name); 927 } 928 929 return 0; 930 } 931 932 fs_initcall(chr_dev_init); 933