1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/drivers/char/mem.c 4 * 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 * 7 * Added devfs support. 8 * Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu> 9 * Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com> 10 */ 11 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/ptrace.h> 23 #include <linux/device.h> 24 #include <linux/highmem.h> 25 #include <linux/backing-dev.h> 26 #include <linux/shmem_fs.h> 27 #include <linux/splice.h> 28 #include <linux/pfn.h> 29 #include <linux/export.h> 30 #include <linux/io.h> 31 #include <linux/uio.h> 32 33 #include <linux/uaccess.h> 34 35 #ifdef CONFIG_IA64 36 # include <linux/efi.h> 37 #endif 38 39 #define DEVPORT_MINOR 4 40 41 static inline unsigned long size_inside_page(unsigned long start, 42 unsigned long size) 43 { 44 unsigned long sz; 45 46 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); 47 48 return min(sz, size); 49 } 50 51 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE 52 static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) 53 { 54 return addr + count <= __pa(high_memory); 55 } 56 57 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 58 { 59 return 1; 60 } 61 #endif 62 63 #ifdef CONFIG_STRICT_DEVMEM 64 static inline int page_is_allowed(unsigned long pfn) 65 { 66 return devmem_is_allowed(pfn); 67 } 68 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 69 { 70 u64 from = ((u64)pfn) << PAGE_SHIFT; 71 u64 to = from + size; 72 u64 cursor = from; 73 74 while (cursor < to) { 75 if (!devmem_is_allowed(pfn)) 76 return 0; 77 cursor += PAGE_SIZE; 78 pfn++; 79 } 80 return 1; 81 } 82 #else 83 static inline int page_is_allowed(unsigned long pfn) 84 { 85 return 1; 86 } 87 static inline int range_is_allowed(unsigned long pfn, unsigned long size) 88 { 89 return 1; 90 } 91 #endif 92 93 #ifndef unxlate_dev_mem_ptr 94 #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr 95 void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr) 96 { 97 } 98 #endif 99 100 /* 101 * This funcion reads the *physical* memory. The f_pos points directly to the 102 * memory location. 103 */ 104 static ssize_t read_mem(struct file *file, char __user *buf, 105 size_t count, loff_t *ppos) 106 { 107 phys_addr_t p = *ppos; 108 ssize_t read, sz; 109 void *ptr; 110 char *bounce; 111 int err; 112 113 if (p != *ppos) 114 return 0; 115 116 if (!valid_phys_addr_range(p, count)) 117 return -EFAULT; 118 read = 0; 119 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 120 /* we don't have page 0 mapped on sparc and m68k.. */ 121 if (p < PAGE_SIZE) { 122 sz = size_inside_page(p, count); 123 if (sz > 0) { 124 if (clear_user(buf, sz)) 125 return -EFAULT; 126 buf += sz; 127 p += sz; 128 count -= sz; 129 read += sz; 130 } 131 } 132 #endif 133 134 bounce = kmalloc(PAGE_SIZE, GFP_KERNEL); 135 if (!bounce) 136 return -ENOMEM; 137 138 while (count > 0) { 139 unsigned long remaining; 140 int allowed, probe; 141 142 sz = size_inside_page(p, count); 143 144 err = -EPERM; 145 allowed = page_is_allowed(p >> PAGE_SHIFT); 146 if (!allowed) 147 goto failed; 148 149 err = -EFAULT; 150 if (allowed == 2) { 151 /* Show zeros for restricted memory. */ 152 remaining = clear_user(buf, sz); 153 } else { 154 /* 155 * On ia64 if a page has been mapped somewhere as 156 * uncached, then it must also be accessed uncached 157 * by the kernel or data corruption may occur. 158 */ 159 ptr = xlate_dev_mem_ptr(p); 160 if (!ptr) 161 goto failed; 162 163 probe = probe_kernel_read(bounce, ptr, sz); 164 unxlate_dev_mem_ptr(p, ptr); 165 if (probe) 166 goto failed; 167 168 remaining = copy_to_user(buf, bounce, sz); 169 } 170 171 if (remaining) 172 goto failed; 173 174 buf += sz; 175 p += sz; 176 count -= sz; 177 read += sz; 178 } 179 kfree(bounce); 180 181 *ppos += read; 182 return read; 183 184 failed: 185 kfree(bounce); 186 return err; 187 } 188 189 static ssize_t write_mem(struct file *file, const char __user *buf, 190 size_t count, loff_t *ppos) 191 { 192 phys_addr_t p = *ppos; 193 ssize_t written, sz; 194 unsigned long copied; 195 void *ptr; 196 197 if (p != *ppos) 198 return -EFBIG; 199 200 if (!valid_phys_addr_range(p, count)) 201 return -EFAULT; 202 203 written = 0; 204 205 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 206 /* we don't have page 0 mapped on sparc and m68k.. */ 207 if (p < PAGE_SIZE) { 208 sz = size_inside_page(p, count); 209 /* Hmm. Do something? */ 210 buf += sz; 211 p += sz; 212 count -= sz; 213 written += sz; 214 } 215 #endif 216 217 while (count > 0) { 218 int allowed; 219 220 sz = size_inside_page(p, count); 221 222 allowed = page_is_allowed(p >> PAGE_SHIFT); 223 if (!allowed) 224 return -EPERM; 225 226 /* Skip actual writing when a page is marked as restricted. */ 227 if (allowed == 1) { 228 /* 229 * On ia64 if a page has been mapped somewhere as 230 * uncached, then it must also be accessed uncached 231 * by the kernel or data corruption may occur. 232 */ 233 ptr = xlate_dev_mem_ptr(p); 234 if (!ptr) { 235 if (written) 236 break; 237 return -EFAULT; 238 } 239 240 copied = copy_from_user(ptr, buf, sz); 241 unxlate_dev_mem_ptr(p, ptr); 242 if (copied) { 243 written += sz - copied; 244 if (written) 245 break; 246 return -EFAULT; 247 } 248 } 249 250 buf += sz; 251 p += sz; 252 count -= sz; 253 written += sz; 254 } 255 256 *ppos += written; 257 return written; 258 } 259 260 int __weak phys_mem_access_prot_allowed(struct file *file, 261 unsigned long pfn, unsigned long size, pgprot_t *vma_prot) 262 { 263 return 1; 264 } 265 266 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT 267 268 /* 269 * Architectures vary in how they handle caching for addresses 270 * outside of main memory. 271 * 272 */ 273 #ifdef pgprot_noncached 274 static int uncached_access(struct file *file, phys_addr_t addr) 275 { 276 #if defined(CONFIG_IA64) 277 /* 278 * On ia64, we ignore O_DSYNC because we cannot tolerate memory 279 * attribute aliases. 280 */ 281 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB); 282 #elif defined(CONFIG_MIPS) 283 { 284 extern int __uncached_access(struct file *file, 285 unsigned long addr); 286 287 return __uncached_access(file, addr); 288 } 289 #else 290 /* 291 * Accessing memory above the top the kernel knows about or through a 292 * file pointer 293 * that was marked O_DSYNC will be done non-cached. 294 */ 295 if (file->f_flags & O_DSYNC) 296 return 1; 297 return addr >= __pa(high_memory); 298 #endif 299 } 300 #endif 301 302 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 303 unsigned long size, pgprot_t vma_prot) 304 { 305 #ifdef pgprot_noncached 306 phys_addr_t offset = pfn << PAGE_SHIFT; 307 308 if (uncached_access(file, offset)) 309 return pgprot_noncached(vma_prot); 310 #endif 311 return vma_prot; 312 } 313 #endif 314 315 #ifndef CONFIG_MMU 316 static unsigned long get_unmapped_area_mem(struct file *file, 317 unsigned long addr, 318 unsigned long len, 319 unsigned long pgoff, 320 unsigned long flags) 321 { 322 if (!valid_mmap_phys_addr_range(pgoff, len)) 323 return (unsigned long) -EINVAL; 324 return pgoff << PAGE_SHIFT; 325 } 326 327 /* permit direct mmap, for read, write or exec */ 328 static unsigned memory_mmap_capabilities(struct file *file) 329 { 330 return NOMMU_MAP_DIRECT | 331 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC; 332 } 333 334 static unsigned zero_mmap_capabilities(struct file *file) 335 { 336 return NOMMU_MAP_COPY; 337 } 338 339 /* can't do an in-place private mapping if there's no MMU */ 340 static inline int private_mapping_ok(struct vm_area_struct *vma) 341 { 342 return vma->vm_flags & VM_MAYSHARE; 343 } 344 #else 345 346 static inline int private_mapping_ok(struct vm_area_struct *vma) 347 { 348 return 1; 349 } 350 #endif 351 352 static const struct vm_operations_struct mmap_mem_ops = { 353 #ifdef CONFIG_HAVE_IOREMAP_PROT 354 .access = generic_access_phys 355 #endif 356 }; 357 358 static int mmap_mem(struct file *file, struct vm_area_struct *vma) 359 { 360 size_t size = vma->vm_end - vma->vm_start; 361 phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; 362 363 /* Does it even fit in phys_addr_t? */ 364 if (offset >> PAGE_SHIFT != vma->vm_pgoff) 365 return -EINVAL; 366 367 /* It's illegal to wrap around the end of the physical address space. */ 368 if (offset + (phys_addr_t)size - 1 < offset) 369 return -EINVAL; 370 371 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) 372 return -EINVAL; 373 374 if (!private_mapping_ok(vma)) 375 return -ENOSYS; 376 377 if (!range_is_allowed(vma->vm_pgoff, size)) 378 return -EPERM; 379 380 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, 381 &vma->vm_page_prot)) 382 return -EINVAL; 383 384 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, 385 size, 386 vma->vm_page_prot); 387 388 vma->vm_ops = &mmap_mem_ops; 389 390 /* Remap-pfn-range will mark the range VM_IO */ 391 if (remap_pfn_range(vma, 392 vma->vm_start, 393 vma->vm_pgoff, 394 size, 395 vma->vm_page_prot)) { 396 return -EAGAIN; 397 } 398 return 0; 399 } 400 401 static int mmap_kmem(struct file *file, struct vm_area_struct *vma) 402 { 403 unsigned long pfn; 404 405 /* Turn a kernel-virtual address into a physical page frame */ 406 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; 407 408 /* 409 * RED-PEN: on some architectures there is more mapped memory than 410 * available in mem_map which pfn_valid checks for. Perhaps should add a 411 * new macro here. 412 * 413 * RED-PEN: vmalloc is not supported right now. 414 */ 415 if (!pfn_valid(pfn)) 416 return -EIO; 417 418 vma->vm_pgoff = pfn; 419 return mmap_mem(file, vma); 420 } 421 422 /* 423 * This function reads the *virtual* memory as seen by the kernel. 424 */ 425 static ssize_t read_kmem(struct file *file, char __user *buf, 426 size_t count, loff_t *ppos) 427 { 428 unsigned long p = *ppos; 429 ssize_t low_count, read, sz; 430 char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ 431 int err = 0; 432 433 read = 0; 434 if (p < (unsigned long) high_memory) { 435 low_count = count; 436 if (count > (unsigned long)high_memory - p) 437 low_count = (unsigned long)high_memory - p; 438 439 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 440 /* we don't have page 0 mapped on sparc and m68k.. */ 441 if (p < PAGE_SIZE && low_count > 0) { 442 sz = size_inside_page(p, low_count); 443 if (clear_user(buf, sz)) 444 return -EFAULT; 445 buf += sz; 446 p += sz; 447 read += sz; 448 low_count -= sz; 449 count -= sz; 450 } 451 #endif 452 while (low_count > 0) { 453 sz = size_inside_page(p, low_count); 454 455 /* 456 * On ia64 if a page has been mapped somewhere as 457 * uncached, then it must also be accessed uncached 458 * by the kernel or data corruption may occur 459 */ 460 kbuf = xlate_dev_kmem_ptr((void *)p); 461 if (!virt_addr_valid(kbuf)) 462 return -ENXIO; 463 464 if (copy_to_user(buf, kbuf, sz)) 465 return -EFAULT; 466 buf += sz; 467 p += sz; 468 read += sz; 469 low_count -= sz; 470 count -= sz; 471 } 472 } 473 474 if (count > 0) { 475 kbuf = (char *)__get_free_page(GFP_KERNEL); 476 if (!kbuf) 477 return -ENOMEM; 478 while (count > 0) { 479 sz = size_inside_page(p, count); 480 if (!is_vmalloc_or_module_addr((void *)p)) { 481 err = -ENXIO; 482 break; 483 } 484 sz = vread(kbuf, (char *)p, sz); 485 if (!sz) 486 break; 487 if (copy_to_user(buf, kbuf, sz)) { 488 err = -EFAULT; 489 break; 490 } 491 count -= sz; 492 buf += sz; 493 read += sz; 494 p += sz; 495 } 496 free_page((unsigned long)kbuf); 497 } 498 *ppos = p; 499 return read ? read : err; 500 } 501 502 503 static ssize_t do_write_kmem(unsigned long p, const char __user *buf, 504 size_t count, loff_t *ppos) 505 { 506 ssize_t written, sz; 507 unsigned long copied; 508 509 written = 0; 510 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED 511 /* we don't have page 0 mapped on sparc and m68k.. */ 512 if (p < PAGE_SIZE) { 513 sz = size_inside_page(p, count); 514 /* Hmm. Do something? */ 515 buf += sz; 516 p += sz; 517 count -= sz; 518 written += sz; 519 } 520 #endif 521 522 while (count > 0) { 523 void *ptr; 524 525 sz = size_inside_page(p, count); 526 527 /* 528 * On ia64 if a page has been mapped somewhere as uncached, then 529 * it must also be accessed uncached by the kernel or data 530 * corruption may occur. 531 */ 532 ptr = xlate_dev_kmem_ptr((void *)p); 533 if (!virt_addr_valid(ptr)) 534 return -ENXIO; 535 536 copied = copy_from_user(ptr, buf, sz); 537 if (copied) { 538 written += sz - copied; 539 if (written) 540 break; 541 return -EFAULT; 542 } 543 buf += sz; 544 p += sz; 545 count -= sz; 546 written += sz; 547 } 548 549 *ppos += written; 550 return written; 551 } 552 553 /* 554 * This function writes to the *virtual* memory as seen by the kernel. 555 */ 556 static ssize_t write_kmem(struct file *file, const char __user *buf, 557 size_t count, loff_t *ppos) 558 { 559 unsigned long p = *ppos; 560 ssize_t wrote = 0; 561 ssize_t virtr = 0; 562 char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ 563 int err = 0; 564 565 if (p < (unsigned long) high_memory) { 566 unsigned long to_write = min_t(unsigned long, count, 567 (unsigned long)high_memory - p); 568 wrote = do_write_kmem(p, buf, to_write, ppos); 569 if (wrote != to_write) 570 return wrote; 571 p += wrote; 572 buf += wrote; 573 count -= wrote; 574 } 575 576 if (count > 0) { 577 kbuf = (char *)__get_free_page(GFP_KERNEL); 578 if (!kbuf) 579 return wrote ? wrote : -ENOMEM; 580 while (count > 0) { 581 unsigned long sz = size_inside_page(p, count); 582 unsigned long n; 583 584 if (!is_vmalloc_or_module_addr((void *)p)) { 585 err = -ENXIO; 586 break; 587 } 588 n = copy_from_user(kbuf, buf, sz); 589 if (n) { 590 err = -EFAULT; 591 break; 592 } 593 vwrite(kbuf, (char *)p, sz); 594 count -= sz; 595 buf += sz; 596 virtr += sz; 597 p += sz; 598 } 599 free_page((unsigned long)kbuf); 600 } 601 602 *ppos = p; 603 return virtr + wrote ? : err; 604 } 605 606 static ssize_t read_port(struct file *file, char __user *buf, 607 size_t count, loff_t *ppos) 608 { 609 unsigned long i = *ppos; 610 char __user *tmp = buf; 611 612 if (!access_ok(buf, count)) 613 return -EFAULT; 614 while (count-- > 0 && i < 65536) { 615 if (__put_user(inb(i), tmp) < 0) 616 return -EFAULT; 617 i++; 618 tmp++; 619 } 620 *ppos = i; 621 return tmp-buf; 622 } 623 624 static ssize_t write_port(struct file *file, const char __user *buf, 625 size_t count, loff_t *ppos) 626 { 627 unsigned long i = *ppos; 628 const char __user *tmp = buf; 629 630 if (!access_ok(buf, count)) 631 return -EFAULT; 632 while (count-- > 0 && i < 65536) { 633 char c; 634 635 if (__get_user(c, tmp)) { 636 if (tmp > buf) 637 break; 638 return -EFAULT; 639 } 640 outb(c, i); 641 i++; 642 tmp++; 643 } 644 *ppos = i; 645 return tmp-buf; 646 } 647 648 static ssize_t read_null(struct file *file, char __user *buf, 649 size_t count, loff_t *ppos) 650 { 651 return 0; 652 } 653 654 static ssize_t write_null(struct file *file, const char __user *buf, 655 size_t count, loff_t *ppos) 656 { 657 return count; 658 } 659 660 static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to) 661 { 662 return 0; 663 } 664 665 static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from) 666 { 667 size_t count = iov_iter_count(from); 668 iov_iter_advance(from, count); 669 return count; 670 } 671 672 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, 673 struct splice_desc *sd) 674 { 675 return sd->len; 676 } 677 678 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, 679 loff_t *ppos, size_t len, unsigned int flags) 680 { 681 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); 682 } 683 684 static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter) 685 { 686 size_t written = 0; 687 688 while (iov_iter_count(iter)) { 689 size_t chunk = iov_iter_count(iter), n; 690 691 if (chunk > PAGE_SIZE) 692 chunk = PAGE_SIZE; /* Just for latency reasons */ 693 n = iov_iter_zero(chunk, iter); 694 if (!n && iov_iter_count(iter)) 695 return written ? written : -EFAULT; 696 written += n; 697 if (signal_pending(current)) 698 return written ? written : -ERESTARTSYS; 699 cond_resched(); 700 } 701 return written; 702 } 703 704 static int mmap_zero(struct file *file, struct vm_area_struct *vma) 705 { 706 #ifndef CONFIG_MMU 707 return -ENOSYS; 708 #endif 709 if (vma->vm_flags & VM_SHARED) 710 return shmem_zero_setup(vma); 711 vma_set_anonymous(vma); 712 return 0; 713 } 714 715 static unsigned long get_unmapped_area_zero(struct file *file, 716 unsigned long addr, unsigned long len, 717 unsigned long pgoff, unsigned long flags) 718 { 719 #ifdef CONFIG_MMU 720 if (flags & MAP_SHARED) { 721 /* 722 * mmap_zero() will call shmem_zero_setup() to create a file, 723 * so use shmem's get_unmapped_area in case it can be huge; 724 * and pass NULL for file as in mmap.c's get_unmapped_area(), 725 * so as not to confuse shmem with our handle on "/dev/zero". 726 */ 727 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags); 728 } 729 730 /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */ 731 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags); 732 #else 733 return -ENOSYS; 734 #endif 735 } 736 737 static ssize_t write_full(struct file *file, const char __user *buf, 738 size_t count, loff_t *ppos) 739 { 740 return -ENOSPC; 741 } 742 743 /* 744 * Special lseek() function for /dev/null and /dev/zero. Most notably, you 745 * can fopen() both devices with "a" now. This was previously impossible. 746 * -- SRB. 747 */ 748 static loff_t null_lseek(struct file *file, loff_t offset, int orig) 749 { 750 return file->f_pos = 0; 751 } 752 753 /* 754 * The memory devices use the full 32/64 bits of the offset, and so we cannot 755 * check against negative addresses: they are ok. The return value is weird, 756 * though, in that case (0). 757 * 758 * also note that seeking relative to the "end of file" isn't supported: 759 * it has no meaning, so it returns -EINVAL. 760 */ 761 static loff_t memory_lseek(struct file *file, loff_t offset, int orig) 762 { 763 loff_t ret; 764 765 inode_lock(file_inode(file)); 766 switch (orig) { 767 case SEEK_CUR: 768 offset += file->f_pos; 769 /* fall through */ 770 case SEEK_SET: 771 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ 772 if ((unsigned long long)offset >= -MAX_ERRNO) { 773 ret = -EOVERFLOW; 774 break; 775 } 776 file->f_pos = offset; 777 ret = file->f_pos; 778 force_successful_syscall_return(); 779 break; 780 default: 781 ret = -EINVAL; 782 } 783 inode_unlock(file_inode(file)); 784 return ret; 785 } 786 787 static int open_port(struct inode *inode, struct file *filp) 788 { 789 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; 790 } 791 792 #define zero_lseek null_lseek 793 #define full_lseek null_lseek 794 #define write_zero write_null 795 #define write_iter_zero write_iter_null 796 #define open_mem open_port 797 #define open_kmem open_mem 798 799 static const struct file_operations __maybe_unused mem_fops = { 800 .llseek = memory_lseek, 801 .read = read_mem, 802 .write = write_mem, 803 .mmap = mmap_mem, 804 .open = open_mem, 805 #ifndef CONFIG_MMU 806 .get_unmapped_area = get_unmapped_area_mem, 807 .mmap_capabilities = memory_mmap_capabilities, 808 #endif 809 }; 810 811 static const struct file_operations __maybe_unused kmem_fops = { 812 .llseek = memory_lseek, 813 .read = read_kmem, 814 .write = write_kmem, 815 .mmap = mmap_kmem, 816 .open = open_kmem, 817 #ifndef CONFIG_MMU 818 .get_unmapped_area = get_unmapped_area_mem, 819 .mmap_capabilities = memory_mmap_capabilities, 820 #endif 821 }; 822 823 static const struct file_operations null_fops = { 824 .llseek = null_lseek, 825 .read = read_null, 826 .write = write_null, 827 .read_iter = read_iter_null, 828 .write_iter = write_iter_null, 829 .splice_write = splice_write_null, 830 }; 831 832 static const struct file_operations __maybe_unused port_fops = { 833 .llseek = memory_lseek, 834 .read = read_port, 835 .write = write_port, 836 .open = open_port, 837 }; 838 839 static const struct file_operations zero_fops = { 840 .llseek = zero_lseek, 841 .write = write_zero, 842 .read_iter = read_iter_zero, 843 .write_iter = write_iter_zero, 844 .mmap = mmap_zero, 845 .get_unmapped_area = get_unmapped_area_zero, 846 #ifndef CONFIG_MMU 847 .mmap_capabilities = zero_mmap_capabilities, 848 #endif 849 }; 850 851 static const struct file_operations full_fops = { 852 .llseek = full_lseek, 853 .read_iter = read_iter_zero, 854 .write = write_full, 855 }; 856 857 static const struct memdev { 858 const char *name; 859 umode_t mode; 860 const struct file_operations *fops; 861 fmode_t fmode; 862 } devlist[] = { 863 #ifdef CONFIG_DEVMEM 864 [1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET }, 865 #endif 866 #ifdef CONFIG_DEVKMEM 867 [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET }, 868 #endif 869 [3] = { "null", 0666, &null_fops, 0 }, 870 #ifdef CONFIG_DEVPORT 871 [4] = { "port", 0, &port_fops, 0 }, 872 #endif 873 [5] = { "zero", 0666, &zero_fops, 0 }, 874 [7] = { "full", 0666, &full_fops, 0 }, 875 [8] = { "random", 0666, &random_fops, 0 }, 876 [9] = { "urandom", 0666, &urandom_fops, 0 }, 877 #ifdef CONFIG_PRINTK 878 [11] = { "kmsg", 0644, &kmsg_fops, 0 }, 879 #endif 880 }; 881 882 static int memory_open(struct inode *inode, struct file *filp) 883 { 884 int minor; 885 const struct memdev *dev; 886 887 minor = iminor(inode); 888 if (minor >= ARRAY_SIZE(devlist)) 889 return -ENXIO; 890 891 dev = &devlist[minor]; 892 if (!dev->fops) 893 return -ENXIO; 894 895 filp->f_op = dev->fops; 896 filp->f_mode |= dev->fmode; 897 898 if (dev->fops->open) 899 return dev->fops->open(inode, filp); 900 901 return 0; 902 } 903 904 static const struct file_operations memory_fops = { 905 .open = memory_open, 906 .llseek = noop_llseek, 907 }; 908 909 static char *mem_devnode(struct device *dev, umode_t *mode) 910 { 911 if (mode && devlist[MINOR(dev->devt)].mode) 912 *mode = devlist[MINOR(dev->devt)].mode; 913 return NULL; 914 } 915 916 static struct class *mem_class; 917 918 static int __init chr_dev_init(void) 919 { 920 int minor; 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; 933 934 /* 935 * Create /dev/port? 936 */ 937 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) 938 continue; 939 940 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), 941 NULL, devlist[minor].name); 942 } 943 944 return tty_init(); 945 } 946 947 fs_initcall(chr_dev_init); 948