Line data Source code
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/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/backing-dev.h>
25 : #include <linux/shmem_fs.h>
26 : #include <linux/splice.h>
27 : #include <linux/pfn.h>
28 : #include <linux/export.h>
29 : #include <linux/io.h>
30 : #include <linux/uio.h>
31 : #include <linux/uaccess.h>
32 : #include <linux/security.h>
33 :
34 : #ifdef CONFIG_IA64
35 : # include <linux/efi.h>
36 : #endif
37 :
38 : #define DEVMEM_MINOR 1
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 0 : sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
47 :
48 0 : 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 0 : 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 0 : static inline bool should_stop_iteration(void)
101 : {
102 0 : if (need_resched())
103 0 : cond_resched();
104 0 : return signal_pending(current);
105 : }
106 :
107 : /*
108 : * This funcion reads the *physical* memory. The f_pos points directly to the
109 : * memory location.
110 : */
111 0 : static ssize_t read_mem(struct file *file, char __user *buf,
112 : size_t count, loff_t *ppos)
113 : {
114 0 : phys_addr_t p = *ppos;
115 : ssize_t read, sz;
116 : void *ptr;
117 : char *bounce;
118 : int err;
119 :
120 : if (p != *ppos)
121 : return 0;
122 :
123 0 : if (!valid_phys_addr_range(p, count))
124 : return -EFAULT;
125 0 : 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 = size_inside_page(p, count);
130 : if (sz > 0) {
131 : if (clear_user(buf, sz))
132 : return -EFAULT;
133 : buf += sz;
134 : p += sz;
135 : count -= sz;
136 : read += sz;
137 : }
138 : }
139 : #endif
140 :
141 0 : bounce = kmalloc(PAGE_SIZE, GFP_KERNEL);
142 0 : if (!bounce)
143 : return -ENOMEM;
144 :
145 0 : while (count > 0) {
146 : unsigned long remaining;
147 : int allowed, probe;
148 :
149 0 : sz = size_inside_page(p, count);
150 :
151 0 : err = -EPERM;
152 0 : allowed = page_is_allowed(p >> PAGE_SHIFT);
153 : if (!allowed)
154 : goto failed;
155 :
156 0 : err = -EFAULT;
157 : if (allowed == 2) {
158 : /* Show zeros for restricted memory. */
159 : remaining = clear_user(buf, sz);
160 : } else {
161 : /*
162 : * On ia64 if a page has been mapped somewhere as
163 : * uncached, then it must also be accessed uncached
164 : * by the kernel or data corruption may occur.
165 : */
166 0 : ptr = xlate_dev_mem_ptr(p);
167 0 : if (!ptr)
168 : goto failed;
169 :
170 0 : probe = copy_from_kernel_nofault(bounce, ptr, sz);
171 0 : unxlate_dev_mem_ptr(p, ptr);
172 0 : if (probe)
173 : goto failed;
174 :
175 0 : remaining = copy_to_user(buf, bounce, sz);
176 : }
177 :
178 0 : if (remaining)
179 : goto failed;
180 :
181 0 : buf += sz;
182 0 : p += sz;
183 0 : count -= sz;
184 0 : read += sz;
185 0 : if (should_stop_iteration())
186 : break;
187 : }
188 0 : kfree(bounce);
189 :
190 0 : *ppos += read;
191 0 : return read;
192 :
193 : failed:
194 0 : kfree(bounce);
195 0 : return err;
196 : }
197 :
198 0 : static ssize_t write_mem(struct file *file, const char __user *buf,
199 : size_t count, loff_t *ppos)
200 : {
201 0 : phys_addr_t p = *ppos;
202 : ssize_t written, sz;
203 : unsigned long copied;
204 : void *ptr;
205 :
206 : if (p != *ppos)
207 : return -EFBIG;
208 :
209 0 : if (!valid_phys_addr_range(p, count))
210 : return -EFAULT;
211 :
212 : written = 0;
213 :
214 : #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
215 : /* we don't have page 0 mapped on sparc and m68k.. */
216 : if (p < PAGE_SIZE) {
217 : sz = size_inside_page(p, count);
218 : /* Hmm. Do something? */
219 : buf += sz;
220 : p += sz;
221 : count -= sz;
222 : written += sz;
223 : }
224 : #endif
225 :
226 0 : while (count > 0) {
227 : int allowed;
228 :
229 0 : sz = size_inside_page(p, count);
230 :
231 0 : allowed = page_is_allowed(p >> PAGE_SHIFT);
232 : if (!allowed)
233 : return -EPERM;
234 :
235 : /* Skip actual writing when a page is marked as restricted. */
236 : if (allowed == 1) {
237 : /*
238 : * On ia64 if a page has been mapped somewhere as
239 : * uncached, then it must also be accessed uncached
240 : * by the kernel or data corruption may occur.
241 : */
242 0 : ptr = xlate_dev_mem_ptr(p);
243 0 : if (!ptr) {
244 0 : if (written)
245 : break;
246 : return -EFAULT;
247 : }
248 :
249 0 : copied = copy_from_user(ptr, buf, sz);
250 0 : unxlate_dev_mem_ptr(p, ptr);
251 0 : if (copied) {
252 0 : written += sz - copied;
253 0 : if (written)
254 : break;
255 : return -EFAULT;
256 : }
257 : }
258 :
259 0 : buf += sz;
260 0 : p += sz;
261 0 : count -= sz;
262 0 : written += sz;
263 0 : if (should_stop_iteration())
264 : break;
265 : }
266 :
267 0 : *ppos += written;
268 0 : return written;
269 : }
270 :
271 0 : int __weak phys_mem_access_prot_allowed(struct file *file,
272 : unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
273 : {
274 0 : return 1;
275 : }
276 :
277 : #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
278 :
279 : /*
280 : * Architectures vary in how they handle caching for addresses
281 : * outside of main memory.
282 : *
283 : */
284 : #ifdef pgprot_noncached
285 : static int uncached_access(struct file *file, phys_addr_t addr)
286 : {
287 : #if defined(CONFIG_IA64)
288 : /*
289 : * On ia64, we ignore O_DSYNC because we cannot tolerate memory
290 : * attribute aliases.
291 : */
292 : return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
293 : #else
294 : /*
295 : * Accessing memory above the top the kernel knows about or through a
296 : * file pointer
297 : * that was marked O_DSYNC will be done non-cached.
298 : */
299 : if (file->f_flags & O_DSYNC)
300 : return 1;
301 : return addr >= __pa(high_memory);
302 : #endif
303 : }
304 : #endif
305 :
306 : static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
307 : unsigned long size, pgprot_t vma_prot)
308 : {
309 : #ifdef pgprot_noncached
310 0 : phys_addr_t offset = pfn << PAGE_SHIFT;
311 :
312 0 : if (uncached_access(file, offset))
313 : return pgprot_noncached(vma_prot);
314 : #endif
315 : return vma_prot;
316 : }
317 : #endif
318 :
319 : #ifndef CONFIG_MMU
320 : static unsigned long get_unmapped_area_mem(struct file *file,
321 : unsigned long addr,
322 : unsigned long len,
323 : unsigned long pgoff,
324 : unsigned long flags)
325 : {
326 : if (!valid_mmap_phys_addr_range(pgoff, len))
327 : return (unsigned long) -EINVAL;
328 : return pgoff << PAGE_SHIFT;
329 : }
330 :
331 : /* permit direct mmap, for read, write or exec */
332 : static unsigned memory_mmap_capabilities(struct file *file)
333 : {
334 : return NOMMU_MAP_DIRECT |
335 : NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
336 : }
337 :
338 : static unsigned zero_mmap_capabilities(struct file *file)
339 : {
340 : return NOMMU_MAP_COPY;
341 : }
342 :
343 : /* can't do an in-place private mapping if there's no MMU */
344 : static inline int private_mapping_ok(struct vm_area_struct *vma)
345 : {
346 : return is_nommu_shared_mapping(vma->vm_flags);
347 : }
348 : #else
349 :
350 : static inline int private_mapping_ok(struct vm_area_struct *vma)
351 : {
352 : return 1;
353 : }
354 : #endif
355 :
356 : static const struct vm_operations_struct mmap_mem_ops = {
357 : #ifdef CONFIG_HAVE_IOREMAP_PROT
358 : .access = generic_access_phys
359 : #endif
360 : };
361 :
362 0 : static int mmap_mem(struct file *file, struct vm_area_struct *vma)
363 : {
364 0 : size_t size = vma->vm_end - vma->vm_start;
365 0 : phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
366 :
367 : /* Does it even fit in phys_addr_t? */
368 0 : if (offset >> PAGE_SHIFT != vma->vm_pgoff)
369 : return -EINVAL;
370 :
371 : /* It's illegal to wrap around the end of the physical address space. */
372 0 : if (offset + (phys_addr_t)size - 1 < offset)
373 : return -EINVAL;
374 :
375 0 : if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
376 : return -EINVAL;
377 :
378 0 : if (!private_mapping_ok(vma))
379 : return -ENOSYS;
380 :
381 0 : if (!range_is_allowed(vma->vm_pgoff, size))
382 : return -EPERM;
383 :
384 0 : if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
385 : &vma->vm_page_prot))
386 : return -EINVAL;
387 :
388 0 : vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
389 : size,
390 : vma->vm_page_prot);
391 :
392 0 : vma->vm_ops = &mmap_mem_ops;
393 :
394 : /* Remap-pfn-range will mark the range VM_IO */
395 0 : if (remap_pfn_range(vma,
396 : vma->vm_start,
397 : vma->vm_pgoff,
398 : size,
399 : vma->vm_page_prot)) {
400 : return -EAGAIN;
401 : }
402 0 : return 0;
403 : }
404 :
405 0 : static ssize_t read_port(struct file *file, char __user *buf,
406 : size_t count, loff_t *ppos)
407 : {
408 0 : unsigned long i = *ppos;
409 0 : char __user *tmp = buf;
410 :
411 0 : if (!access_ok(buf, count))
412 : return -EFAULT;
413 0 : while (count-- > 0 && i < 65536) {
414 0 : if (__put_user(inb(i), tmp) < 0)
415 : return -EFAULT;
416 0 : i++;
417 0 : tmp++;
418 : }
419 0 : *ppos = i;
420 0 : return tmp-buf;
421 : }
422 :
423 0 : static ssize_t write_port(struct file *file, const char __user *buf,
424 : size_t count, loff_t *ppos)
425 : {
426 0 : unsigned long i = *ppos;
427 0 : const char __user *tmp = buf;
428 :
429 0 : if (!access_ok(buf, count))
430 : return -EFAULT;
431 0 : while (count-- > 0 && i < 65536) {
432 : char c;
433 :
434 0 : if (__get_user(c, tmp)) {
435 0 : if (tmp > buf)
436 : break;
437 : return -EFAULT;
438 : }
439 0 : outb(c, i);
440 0 : i++;
441 0 : tmp++;
442 : }
443 0 : *ppos = i;
444 0 : return tmp-buf;
445 : }
446 :
447 0 : static ssize_t read_null(struct file *file, char __user *buf,
448 : size_t count, loff_t *ppos)
449 : {
450 0 : return 0;
451 : }
452 :
453 0 : static ssize_t write_null(struct file *file, const char __user *buf,
454 : size_t count, loff_t *ppos)
455 : {
456 0 : return count;
457 : }
458 :
459 0 : static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
460 : {
461 0 : return 0;
462 : }
463 :
464 0 : static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
465 : {
466 0 : size_t count = iov_iter_count(from);
467 0 : iov_iter_advance(from, count);
468 0 : return count;
469 : }
470 :
471 0 : static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
472 : struct splice_desc *sd)
473 : {
474 0 : return sd->len;
475 : }
476 :
477 0 : static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
478 : loff_t *ppos, size_t len, unsigned int flags)
479 : {
480 0 : return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
481 : }
482 :
483 0 : static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
484 : {
485 0 : return 0;
486 : }
487 :
488 0 : static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
489 : {
490 0 : size_t written = 0;
491 :
492 0 : while (iov_iter_count(iter)) {
493 0 : size_t chunk = iov_iter_count(iter), n;
494 :
495 0 : if (chunk > PAGE_SIZE)
496 0 : chunk = PAGE_SIZE; /* Just for latency reasons */
497 0 : n = iov_iter_zero(chunk, iter);
498 0 : if (!n && iov_iter_count(iter))
499 0 : return written ? written : -EFAULT;
500 0 : written += n;
501 0 : if (signal_pending(current))
502 0 : return written ? written : -ERESTARTSYS;
503 0 : if (!need_resched())
504 0 : continue;
505 0 : if (iocb->ki_flags & IOCB_NOWAIT)
506 0 : return written ? written : -EAGAIN;
507 0 : cond_resched();
508 : }
509 0 : return written;
510 : }
511 :
512 0 : static ssize_t read_zero(struct file *file, char __user *buf,
513 : size_t count, loff_t *ppos)
514 : {
515 0 : size_t cleared = 0;
516 :
517 0 : while (count) {
518 0 : size_t chunk = min_t(size_t, count, PAGE_SIZE);
519 : size_t left;
520 :
521 0 : left = clear_user(buf + cleared, chunk);
522 0 : if (unlikely(left)) {
523 0 : cleared += (chunk - left);
524 0 : if (!cleared)
525 : return -EFAULT;
526 : break;
527 : }
528 0 : cleared += chunk;
529 0 : count -= chunk;
530 :
531 0 : if (signal_pending(current))
532 : break;
533 0 : cond_resched();
534 : }
535 :
536 0 : return cleared;
537 : }
538 :
539 0 : static int mmap_zero(struct file *file, struct vm_area_struct *vma)
540 : {
541 : #ifndef CONFIG_MMU
542 : return -ENOSYS;
543 : #endif
544 0 : if (vma->vm_flags & VM_SHARED)
545 0 : return shmem_zero_setup(vma);
546 0 : vma_set_anonymous(vma);
547 0 : return 0;
548 : }
549 :
550 0 : static unsigned long get_unmapped_area_zero(struct file *file,
551 : unsigned long addr, unsigned long len,
552 : unsigned long pgoff, unsigned long flags)
553 : {
554 : #ifdef CONFIG_MMU
555 0 : if (flags & MAP_SHARED) {
556 : /*
557 : * mmap_zero() will call shmem_zero_setup() to create a file,
558 : * so use shmem's get_unmapped_area in case it can be huge;
559 : * and pass NULL for file as in mmap.c's get_unmapped_area(),
560 : * so as not to confuse shmem with our handle on "/dev/zero".
561 : */
562 0 : return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
563 : }
564 :
565 : /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
566 0 : return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
567 : #else
568 : return -ENOSYS;
569 : #endif
570 : }
571 :
572 0 : static ssize_t write_full(struct file *file, const char __user *buf,
573 : size_t count, loff_t *ppos)
574 : {
575 0 : return -ENOSPC;
576 : }
577 :
578 : /*
579 : * Special lseek() function for /dev/null and /dev/zero. Most notably, you
580 : * can fopen() both devices with "a" now. This was previously impossible.
581 : * -- SRB.
582 : */
583 0 : static loff_t null_lseek(struct file *file, loff_t offset, int orig)
584 : {
585 0 : return file->f_pos = 0;
586 : }
587 :
588 : /*
589 : * The memory devices use the full 32/64 bits of the offset, and so we cannot
590 : * check against negative addresses: they are ok. The return value is weird,
591 : * though, in that case (0).
592 : *
593 : * also note that seeking relative to the "end of file" isn't supported:
594 : * it has no meaning, so it returns -EINVAL.
595 : */
596 0 : static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
597 : {
598 : loff_t ret;
599 :
600 0 : inode_lock(file_inode(file));
601 0 : switch (orig) {
602 : case SEEK_CUR:
603 0 : offset += file->f_pos;
604 : fallthrough;
605 : case SEEK_SET:
606 : /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
607 0 : if ((unsigned long long)offset >= -MAX_ERRNO) {
608 : ret = -EOVERFLOW;
609 : break;
610 : }
611 0 : file->f_pos = offset;
612 0 : ret = file->f_pos;
613 : force_successful_syscall_return();
614 0 : break;
615 : default:
616 : ret = -EINVAL;
617 : }
618 0 : inode_unlock(file_inode(file));
619 0 : return ret;
620 : }
621 :
622 0 : static int open_port(struct inode *inode, struct file *filp)
623 : {
624 : int rc;
625 :
626 0 : if (!capable(CAP_SYS_RAWIO))
627 : return -EPERM;
628 :
629 0 : rc = security_locked_down(LOCKDOWN_DEV_MEM);
630 : if (rc)
631 : return rc;
632 :
633 0 : if (iminor(inode) != DEVMEM_MINOR)
634 : return 0;
635 :
636 : /*
637 : * Use a unified address space to have a single point to manage
638 : * revocations when drivers want to take over a /dev/mem mapped
639 : * range.
640 : */
641 0 : filp->f_mapping = iomem_get_mapping();
642 :
643 0 : return 0;
644 : }
645 :
646 : #define zero_lseek null_lseek
647 : #define full_lseek null_lseek
648 : #define write_zero write_null
649 : #define write_iter_zero write_iter_null
650 : #define open_mem open_port
651 :
652 : static const struct file_operations __maybe_unused mem_fops = {
653 : .llseek = memory_lseek,
654 : .read = read_mem,
655 : .write = write_mem,
656 : .mmap = mmap_mem,
657 : .open = open_mem,
658 : #ifndef CONFIG_MMU
659 : .get_unmapped_area = get_unmapped_area_mem,
660 : .mmap_capabilities = memory_mmap_capabilities,
661 : #endif
662 : };
663 :
664 : static const struct file_operations null_fops = {
665 : .llseek = null_lseek,
666 : .read = read_null,
667 : .write = write_null,
668 : .read_iter = read_iter_null,
669 : .write_iter = write_iter_null,
670 : .splice_write = splice_write_null,
671 : .uring_cmd = uring_cmd_null,
672 : };
673 :
674 : static const struct file_operations __maybe_unused port_fops = {
675 : .llseek = memory_lseek,
676 : .read = read_port,
677 : .write = write_port,
678 : .open = open_port,
679 : };
680 :
681 : static const struct file_operations zero_fops = {
682 : .llseek = zero_lseek,
683 : .write = write_zero,
684 : .read_iter = read_iter_zero,
685 : .read = read_zero,
686 : .write_iter = write_iter_zero,
687 : .mmap = mmap_zero,
688 : .get_unmapped_area = get_unmapped_area_zero,
689 : #ifndef CONFIG_MMU
690 : .mmap_capabilities = zero_mmap_capabilities,
691 : #endif
692 : };
693 :
694 : static const struct file_operations full_fops = {
695 : .llseek = full_lseek,
696 : .read_iter = read_iter_zero,
697 : .write = write_full,
698 : };
699 :
700 : static const struct memdev {
701 : const char *name;
702 : umode_t mode;
703 : const struct file_operations *fops;
704 : fmode_t fmode;
705 : } devlist[] = {
706 : #ifdef CONFIG_DEVMEM
707 : [DEVMEM_MINOR] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
708 : #endif
709 : [3] = { "null", 0666, &null_fops, FMODE_NOWAIT },
710 : #ifdef CONFIG_DEVPORT
711 : [4] = { "port", 0, &port_fops, 0 },
712 : #endif
713 : [5] = { "zero", 0666, &zero_fops, FMODE_NOWAIT },
714 : [7] = { "full", 0666, &full_fops, 0 },
715 : [8] = { "random", 0666, &random_fops, FMODE_NOWAIT },
716 : [9] = { "urandom", 0666, &urandom_fops, FMODE_NOWAIT },
717 : #ifdef CONFIG_PRINTK
718 : [11] = { "kmsg", 0644, &kmsg_fops, 0 },
719 : #endif
720 : };
721 :
722 0 : static int memory_open(struct inode *inode, struct file *filp)
723 : {
724 : int minor;
725 : const struct memdev *dev;
726 :
727 0 : minor = iminor(inode);
728 0 : if (minor >= ARRAY_SIZE(devlist))
729 : return -ENXIO;
730 :
731 0 : dev = &devlist[minor];
732 0 : if (!dev->fops)
733 : return -ENXIO;
734 :
735 0 : filp->f_op = dev->fops;
736 0 : filp->f_mode |= dev->fmode;
737 :
738 0 : if (dev->fops->open)
739 0 : return dev->fops->open(inode, filp);
740 :
741 : return 0;
742 : }
743 :
744 : static const struct file_operations memory_fops = {
745 : .open = memory_open,
746 : .llseek = noop_llseek,
747 : };
748 :
749 8 : static char *mem_devnode(const struct device *dev, umode_t *mode)
750 : {
751 8 : if (mode && devlist[MINOR(dev->devt)].mode)
752 6 : *mode = devlist[MINOR(dev->devt)].mode;
753 8 : return NULL;
754 : }
755 :
756 : static struct class *mem_class;
757 :
758 1 : static int __init chr_dev_init(void)
759 : {
760 : int minor;
761 :
762 1 : if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
763 0 : printk("unable to get major %d for memory devs\n", MEM_MAJOR);
764 :
765 1 : mem_class = class_create("mem");
766 2 : if (IS_ERR(mem_class))
767 0 : return PTR_ERR(mem_class);
768 :
769 1 : mem_class->devnode = mem_devnode;
770 12 : for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
771 11 : if (!devlist[minor].name)
772 3 : continue;
773 :
774 : /*
775 : * Create /dev/port?
776 : */
777 : if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
778 : continue;
779 :
780 8 : device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
781 : NULL, devlist[minor].name);
782 : }
783 :
784 1 : return tty_init();
785 : }
786 :
787 : fs_initcall(chr_dev_init);
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