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 | #define DEVMEM_MINOR 1 |
35 | #define DEVPORT_MINOR 4 |
36 | |
37 | static 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 |
48 | static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) |
49 | { |
50 | return addr + count <= __pa(high_memory); |
51 | } |
52 | |
53 | static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) |
54 | { |
55 | return 1; |
56 | } |
57 | #endif |
58 | |
59 | #ifdef CONFIG_STRICT_DEVMEM |
60 | static inline int page_is_allowed(unsigned long pfn) |
61 | { |
62 | return devmem_is_allowed(pfn); |
63 | } |
64 | static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
65 | { |
66 | u64 from = ((u64)pfn) << PAGE_SHIFT; |
67 | u64 to = from + size; |
68 | u64 cursor = from; |
69 | |
70 | while (cursor < to) { |
71 | if (!devmem_is_allowed(pfn)) |
72 | return 0; |
73 | cursor += PAGE_SIZE; |
74 | pfn++; |
75 | } |
76 | return 1; |
77 | } |
78 | #else |
79 | static inline int page_is_allowed(unsigned long pfn) |
80 | { |
81 | return 1; |
82 | } |
83 | static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
84 | { |
85 | return 1; |
86 | } |
87 | #endif |
88 | |
89 | static inline bool should_stop_iteration(void) |
90 | { |
91 | if (need_resched()) |
92 | cond_resched(); |
93 | return signal_pending(current); |
94 | } |
95 | |
96 | /* |
97 | * This funcion reads the *physical* memory. The f_pos points directly to the |
98 | * memory location. |
99 | */ |
100 | static ssize_t read_mem(struct file *file, char __user *buf, |
101 | size_t count, loff_t *ppos) |
102 | { |
103 | phys_addr_t p = *ppos; |
104 | ssize_t read, sz; |
105 | void *ptr; |
106 | char *bounce; |
107 | int err; |
108 | |
109 | if (p != *ppos) |
110 | return 0; |
111 | |
112 | if (!valid_phys_addr_range(addr: p, size: count)) |
113 | return -EFAULT; |
114 | read = 0; |
115 | #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED |
116 | /* we don't have page 0 mapped on sparc and m68k.. */ |
117 | if (p < PAGE_SIZE) { |
118 | sz = size_inside_page(p, count); |
119 | if (sz > 0) { |
120 | if (clear_user(buf, sz)) |
121 | return -EFAULT; |
122 | buf += sz; |
123 | p += sz; |
124 | count -= sz; |
125 | read += sz; |
126 | } |
127 | } |
128 | #endif |
129 | |
130 | bounce = kmalloc(PAGE_SIZE, GFP_KERNEL); |
131 | if (!bounce) |
132 | return -ENOMEM; |
133 | |
134 | while (count > 0) { |
135 | unsigned long remaining; |
136 | int allowed, probe; |
137 | |
138 | sz = size_inside_page(start: p, size: count); |
139 | |
140 | err = -EPERM; |
141 | allowed = page_is_allowed(pfn: p >> PAGE_SHIFT); |
142 | if (!allowed) |
143 | goto failed; |
144 | |
145 | err = -EFAULT; |
146 | if (allowed == 2) { |
147 | /* Show zeros for restricted memory. */ |
148 | remaining = clear_user(to: buf, n: sz); |
149 | } else { |
150 | /* |
151 | * On ia64 if a page has been mapped somewhere as |
152 | * uncached, then it must also be accessed uncached |
153 | * by the kernel or data corruption may occur. |
154 | */ |
155 | ptr = xlate_dev_mem_ptr(phys: p); |
156 | if (!ptr) |
157 | goto failed; |
158 | |
159 | probe = copy_from_kernel_nofault(dst: bounce, src: ptr, size: sz); |
160 | unxlate_dev_mem_ptr(phys: p, addr: ptr); |
161 | if (probe) |
162 | goto failed; |
163 | |
164 | remaining = copy_to_user(to: buf, from: bounce, n: sz); |
165 | } |
166 | |
167 | if (remaining) |
168 | goto failed; |
169 | |
170 | buf += sz; |
171 | p += sz; |
172 | count -= sz; |
173 | read += sz; |
174 | if (should_stop_iteration()) |
175 | break; |
176 | } |
177 | kfree(objp: bounce); |
178 | |
179 | *ppos += read; |
180 | return read; |
181 | |
182 | failed: |
183 | kfree(objp: bounce); |
184 | return err; |
185 | } |
186 | |
187 | static ssize_t write_mem(struct file *file, const char __user *buf, |
188 | size_t count, loff_t *ppos) |
189 | { |
190 | phys_addr_t p = *ppos; |
191 | ssize_t written, sz; |
192 | unsigned long copied; |
193 | void *ptr; |
194 | |
195 | if (p != *ppos) |
196 | return -EFBIG; |
197 | |
198 | if (!valid_phys_addr_range(addr: p, size: count)) |
199 | return -EFAULT; |
200 | |
201 | written = 0; |
202 | |
203 | #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED |
204 | /* we don't have page 0 mapped on sparc and m68k.. */ |
205 | if (p < PAGE_SIZE) { |
206 | sz = size_inside_page(p, count); |
207 | /* Hmm. Do something? */ |
208 | buf += sz; |
209 | p += sz; |
210 | count -= sz; |
211 | written += sz; |
212 | } |
213 | #endif |
214 | |
215 | while (count > 0) { |
216 | int allowed; |
217 | |
218 | sz = size_inside_page(start: p, size: count); |
219 | |
220 | allowed = page_is_allowed(pfn: p >> PAGE_SHIFT); |
221 | if (!allowed) |
222 | return -EPERM; |
223 | |
224 | /* Skip actual writing when a page is marked as restricted. */ |
225 | if (allowed == 1) { |
226 | /* |
227 | * On ia64 if a page has been mapped somewhere as |
228 | * uncached, then it must also be accessed uncached |
229 | * by the kernel or data corruption may occur. |
230 | */ |
231 | ptr = xlate_dev_mem_ptr(phys: p); |
232 | if (!ptr) { |
233 | if (written) |
234 | break; |
235 | return -EFAULT; |
236 | } |
237 | |
238 | copied = copy_from_user(to: ptr, from: buf, n: sz); |
239 | unxlate_dev_mem_ptr(phys: p, addr: ptr); |
240 | if (copied) { |
241 | written += sz - copied; |
242 | if (written) |
243 | break; |
244 | return -EFAULT; |
245 | } |
246 | } |
247 | |
248 | buf += sz; |
249 | p += sz; |
250 | count -= sz; |
251 | written += sz; |
252 | if (should_stop_iteration()) |
253 | break; |
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 | /* |
277 | * Accessing memory above the top the kernel knows about or through a |
278 | * file pointer |
279 | * that was marked O_DSYNC will be done non-cached. |
280 | */ |
281 | if (file->f_flags & O_DSYNC) |
282 | return 1; |
283 | return addr >= __pa(high_memory); |
284 | } |
285 | #endif |
286 | |
287 | static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, |
288 | unsigned long size, pgprot_t vma_prot) |
289 | { |
290 | #ifdef pgprot_noncached |
291 | phys_addr_t offset = pfn << PAGE_SHIFT; |
292 | |
293 | if (uncached_access(file, offset)) |
294 | return pgprot_noncached(vma_prot); |
295 | #endif |
296 | return vma_prot; |
297 | } |
298 | #endif |
299 | |
300 | #ifndef CONFIG_MMU |
301 | static unsigned long get_unmapped_area_mem(struct file *file, |
302 | unsigned long addr, |
303 | unsigned long len, |
304 | unsigned long pgoff, |
305 | unsigned long flags) |
306 | { |
307 | if (!valid_mmap_phys_addr_range(pgoff, len)) |
308 | return (unsigned long) -EINVAL; |
309 | return pgoff << PAGE_SHIFT; |
310 | } |
311 | |
312 | /* permit direct mmap, for read, write or exec */ |
313 | static unsigned memory_mmap_capabilities(struct file *file) |
314 | { |
315 | return NOMMU_MAP_DIRECT | |
316 | NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC; |
317 | } |
318 | |
319 | static unsigned zero_mmap_capabilities(struct file *file) |
320 | { |
321 | return NOMMU_MAP_COPY; |
322 | } |
323 | |
324 | /* can't do an in-place private mapping if there's no MMU */ |
325 | static inline int private_mapping_ok(struct vm_area_struct *vma) |
326 | { |
327 | return is_nommu_shared_mapping(vma->vm_flags); |
328 | } |
329 | #else |
330 | |
331 | static inline int private_mapping_ok(struct vm_area_struct *vma) |
332 | { |
333 | return 1; |
334 | } |
335 | #endif |
336 | |
337 | static const struct vm_operations_struct mmap_mem_ops = { |
338 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
339 | .access = generic_access_phys |
340 | #endif |
341 | }; |
342 | |
343 | static int mmap_mem(struct file *file, struct vm_area_struct *vma) |
344 | { |
345 | size_t size = vma->vm_end - vma->vm_start; |
346 | phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; |
347 | |
348 | /* Does it even fit in phys_addr_t? */ |
349 | if (offset >> PAGE_SHIFT != vma->vm_pgoff) |
350 | return -EINVAL; |
351 | |
352 | /* It's illegal to wrap around the end of the physical address space. */ |
353 | if (offset + (phys_addr_t)size - 1 < offset) |
354 | return -EINVAL; |
355 | |
356 | if (!valid_mmap_phys_addr_range(pfn: vma->vm_pgoff, size)) |
357 | return -EINVAL; |
358 | |
359 | if (!private_mapping_ok(vma)) |
360 | return -ENOSYS; |
361 | |
362 | if (!range_is_allowed(pfn: vma->vm_pgoff, size)) |
363 | return -EPERM; |
364 | |
365 | if (!phys_mem_access_prot_allowed(file, pfn: vma->vm_pgoff, size, |
366 | vma_prot: &vma->vm_page_prot)) |
367 | return -EINVAL; |
368 | |
369 | vma->vm_page_prot = phys_mem_access_prot(file, pfn: vma->vm_pgoff, |
370 | size, |
371 | vma_prot: vma->vm_page_prot); |
372 | |
373 | vma->vm_ops = &mmap_mem_ops; |
374 | |
375 | /* Remap-pfn-range will mark the range VM_IO */ |
376 | if (remap_pfn_range(vma, |
377 | addr: vma->vm_start, |
378 | pfn: vma->vm_pgoff, |
379 | size, |
380 | vma->vm_page_prot)) { |
381 | return -EAGAIN; |
382 | } |
383 | return 0; |
384 | } |
385 | |
386 | static ssize_t read_port(struct file *file, char __user *buf, |
387 | size_t count, loff_t *ppos) |
388 | { |
389 | unsigned long i = *ppos; |
390 | char __user *tmp = buf; |
391 | |
392 | if (!access_ok(buf, count)) |
393 | return -EFAULT; |
394 | while (count-- > 0 && i < 65536) { |
395 | if (__put_user(inb(i), tmp) < 0) |
396 | return -EFAULT; |
397 | i++; |
398 | tmp++; |
399 | } |
400 | *ppos = i; |
401 | return tmp-buf; |
402 | } |
403 | |
404 | static ssize_t write_port(struct file *file, const char __user *buf, |
405 | size_t count, loff_t *ppos) |
406 | { |
407 | unsigned long i = *ppos; |
408 | const char __user *tmp = buf; |
409 | |
410 | if (!access_ok(buf, count)) |
411 | return -EFAULT; |
412 | while (count-- > 0 && i < 65536) { |
413 | char c; |
414 | |
415 | if (__get_user(c, tmp)) { |
416 | if (tmp > buf) |
417 | break; |
418 | return -EFAULT; |
419 | } |
420 | outb(value: c, port: i); |
421 | i++; |
422 | tmp++; |
423 | } |
424 | *ppos = i; |
425 | return tmp-buf; |
426 | } |
427 | |
428 | static ssize_t read_null(struct file *file, char __user *buf, |
429 | size_t count, loff_t *ppos) |
430 | { |
431 | return 0; |
432 | } |
433 | |
434 | static ssize_t write_null(struct file *file, const char __user *buf, |
435 | size_t count, loff_t *ppos) |
436 | { |
437 | return count; |
438 | } |
439 | |
440 | static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to) |
441 | { |
442 | return 0; |
443 | } |
444 | |
445 | static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from) |
446 | { |
447 | size_t count = iov_iter_count(i: from); |
448 | iov_iter_advance(i: from, bytes: count); |
449 | return count; |
450 | } |
451 | |
452 | static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, |
453 | struct splice_desc *sd) |
454 | { |
455 | return sd->len; |
456 | } |
457 | |
458 | static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, |
459 | loff_t *ppos, size_t len, unsigned int flags) |
460 | { |
461 | return splice_from_pipe(pipe, out, ppos, len, flags, actor: pipe_to_null); |
462 | } |
463 | |
464 | static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags) |
465 | { |
466 | return 0; |
467 | } |
468 | |
469 | static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter) |
470 | { |
471 | size_t written = 0; |
472 | |
473 | while (iov_iter_count(i: iter)) { |
474 | size_t chunk = iov_iter_count(i: iter), n; |
475 | |
476 | if (chunk > PAGE_SIZE) |
477 | chunk = PAGE_SIZE; /* Just for latency reasons */ |
478 | n = iov_iter_zero(bytes: chunk, iter); |
479 | if (!n && iov_iter_count(i: iter)) |
480 | return written ? written : -EFAULT; |
481 | written += n; |
482 | if (signal_pending(current)) |
483 | return written ? written : -ERESTARTSYS; |
484 | if (!need_resched()) |
485 | continue; |
486 | if (iocb->ki_flags & IOCB_NOWAIT) |
487 | return written ? written : -EAGAIN; |
488 | cond_resched(); |
489 | } |
490 | return written; |
491 | } |
492 | |
493 | static ssize_t read_zero(struct file *file, char __user *buf, |
494 | size_t count, loff_t *ppos) |
495 | { |
496 | size_t cleared = 0; |
497 | |
498 | while (count) { |
499 | size_t chunk = min_t(size_t, count, PAGE_SIZE); |
500 | size_t left; |
501 | |
502 | left = clear_user(to: buf + cleared, n: chunk); |
503 | if (unlikely(left)) { |
504 | cleared += (chunk - left); |
505 | if (!cleared) |
506 | return -EFAULT; |
507 | break; |
508 | } |
509 | cleared += chunk; |
510 | count -= chunk; |
511 | |
512 | if (signal_pending(current)) |
513 | break; |
514 | cond_resched(); |
515 | } |
516 | |
517 | return cleared; |
518 | } |
519 | |
520 | static int mmap_zero(struct file *file, struct vm_area_struct *vma) |
521 | { |
522 | #ifndef CONFIG_MMU |
523 | return -ENOSYS; |
524 | #endif |
525 | if (vma->vm_flags & VM_SHARED) |
526 | return shmem_zero_setup(vma); |
527 | vma_set_anonymous(vma); |
528 | return 0; |
529 | } |
530 | |
531 | static unsigned long get_unmapped_area_zero(struct file *file, |
532 | unsigned long addr, unsigned long len, |
533 | unsigned long pgoff, unsigned long flags) |
534 | { |
535 | #ifdef CONFIG_MMU |
536 | if (flags & MAP_SHARED) { |
537 | /* |
538 | * mmap_zero() will call shmem_zero_setup() to create a file, |
539 | * so use shmem's get_unmapped_area in case it can be huge; |
540 | * and pass NULL for file as in mmap.c's get_unmapped_area(), |
541 | * so as not to confuse shmem with our handle on "/dev/zero". |
542 | */ |
543 | return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags); |
544 | } |
545 | |
546 | /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */ |
547 | return current->mm->get_unmapped_area(file, addr, len, pgoff, flags); |
548 | #else |
549 | return -ENOSYS; |
550 | #endif |
551 | } |
552 | |
553 | static ssize_t write_full(struct file *file, const char __user *buf, |
554 | size_t count, loff_t *ppos) |
555 | { |
556 | return -ENOSPC; |
557 | } |
558 | |
559 | /* |
560 | * Special lseek() function for /dev/null and /dev/zero. Most notably, you |
561 | * can fopen() both devices with "a" now. This was previously impossible. |
562 | * -- SRB. |
563 | */ |
564 | static loff_t null_lseek(struct file *file, loff_t offset, int orig) |
565 | { |
566 | return file->f_pos = 0; |
567 | } |
568 | |
569 | /* |
570 | * The memory devices use the full 32/64 bits of the offset, and so we cannot |
571 | * check against negative addresses: they are ok. The return value is weird, |
572 | * though, in that case (0). |
573 | * |
574 | * also note that seeking relative to the "end of file" isn't supported: |
575 | * it has no meaning, so it returns -EINVAL. |
576 | */ |
577 | static loff_t memory_lseek(struct file *file, loff_t offset, int orig) |
578 | { |
579 | loff_t ret; |
580 | |
581 | inode_lock(inode: file_inode(f: file)); |
582 | switch (orig) { |
583 | case SEEK_CUR: |
584 | offset += file->f_pos; |
585 | fallthrough; |
586 | case SEEK_SET: |
587 | /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ |
588 | if ((unsigned long long)offset >= -MAX_ERRNO) { |
589 | ret = -EOVERFLOW; |
590 | break; |
591 | } |
592 | file->f_pos = offset; |
593 | ret = file->f_pos; |
594 | force_successful_syscall_return(); |
595 | break; |
596 | default: |
597 | ret = -EINVAL; |
598 | } |
599 | inode_unlock(inode: file_inode(f: file)); |
600 | return ret; |
601 | } |
602 | |
603 | static int open_port(struct inode *inode, struct file *filp) |
604 | { |
605 | int rc; |
606 | |
607 | if (!capable(CAP_SYS_RAWIO)) |
608 | return -EPERM; |
609 | |
610 | rc = security_locked_down(what: LOCKDOWN_DEV_MEM); |
611 | if (rc) |
612 | return rc; |
613 | |
614 | if (iminor(inode) != DEVMEM_MINOR) |
615 | return 0; |
616 | |
617 | /* |
618 | * Use a unified address space to have a single point to manage |
619 | * revocations when drivers want to take over a /dev/mem mapped |
620 | * range. |
621 | */ |
622 | filp->f_mapping = iomem_get_mapping(); |
623 | |
624 | return 0; |
625 | } |
626 | |
627 | #define zero_lseek null_lseek |
628 | #define full_lseek null_lseek |
629 | #define write_zero write_null |
630 | #define write_iter_zero write_iter_null |
631 | #define splice_write_zero splice_write_null |
632 | #define open_mem open_port |
633 | |
634 | static const struct file_operations __maybe_unused mem_fops = { |
635 | .llseek = memory_lseek, |
636 | .read = read_mem, |
637 | .write = write_mem, |
638 | .mmap = mmap_mem, |
639 | .open = open_mem, |
640 | #ifndef CONFIG_MMU |
641 | .get_unmapped_area = get_unmapped_area_mem, |
642 | .mmap_capabilities = memory_mmap_capabilities, |
643 | #endif |
644 | }; |
645 | |
646 | static const struct file_operations null_fops = { |
647 | .llseek = null_lseek, |
648 | .read = read_null, |
649 | .write = write_null, |
650 | .read_iter = read_iter_null, |
651 | .write_iter = write_iter_null, |
652 | .splice_write = splice_write_null, |
653 | .uring_cmd = uring_cmd_null, |
654 | }; |
655 | |
656 | static const struct file_operations __maybe_unused port_fops = { |
657 | .llseek = memory_lseek, |
658 | .read = read_port, |
659 | .write = write_port, |
660 | .open = open_port, |
661 | }; |
662 | |
663 | static const struct file_operations zero_fops = { |
664 | .llseek = zero_lseek, |
665 | .write = write_zero, |
666 | .read_iter = read_iter_zero, |
667 | .read = read_zero, |
668 | .write_iter = write_iter_zero, |
669 | .splice_read = copy_splice_read, |
670 | .splice_write = splice_write_zero, |
671 | .mmap = mmap_zero, |
672 | .get_unmapped_area = get_unmapped_area_zero, |
673 | #ifndef CONFIG_MMU |
674 | .mmap_capabilities = zero_mmap_capabilities, |
675 | #endif |
676 | }; |
677 | |
678 | static const struct file_operations full_fops = { |
679 | .llseek = full_lseek, |
680 | .read_iter = read_iter_zero, |
681 | .write = write_full, |
682 | .splice_read = copy_splice_read, |
683 | }; |
684 | |
685 | static const struct memdev { |
686 | const char *name; |
687 | const struct file_operations *fops; |
688 | fmode_t fmode; |
689 | umode_t mode; |
690 | } devlist[] = { |
691 | #ifdef CONFIG_DEVMEM |
692 | [DEVMEM_MINOR] = { .name: "mem", .fops: &mem_fops, FMODE_UNSIGNED_OFFSET, .mode: 0 }, |
693 | #endif |
694 | [3] = { "null", &null_fops, FMODE_NOWAIT, 0666 }, |
695 | #ifdef CONFIG_DEVPORT |
696 | [4] = { "port", &port_fops, 0, 0 }, |
697 | #endif |
698 | [5] = { "zero", &zero_fops, FMODE_NOWAIT, 0666 }, |
699 | [7] = { "full", &full_fops, 0, 0666 }, |
700 | [8] = { "random", &random_fops, FMODE_NOWAIT, 0666 }, |
701 | [9] = { "urandom", &urandom_fops, FMODE_NOWAIT, 0666 }, |
702 | #ifdef CONFIG_PRINTK |
703 | [11] = { "kmsg", &kmsg_fops, 0, 0644 }, |
704 | #endif |
705 | }; |
706 | |
707 | static int memory_open(struct inode *inode, struct file *filp) |
708 | { |
709 | int minor; |
710 | const struct memdev *dev; |
711 | |
712 | minor = iminor(inode); |
713 | if (minor >= ARRAY_SIZE(devlist)) |
714 | return -ENXIO; |
715 | |
716 | dev = &devlist[minor]; |
717 | if (!dev->fops) |
718 | return -ENXIO; |
719 | |
720 | filp->f_op = dev->fops; |
721 | filp->f_mode |= dev->fmode; |
722 | |
723 | if (dev->fops->open) |
724 | return dev->fops->open(inode, filp); |
725 | |
726 | return 0; |
727 | } |
728 | |
729 | static const struct file_operations memory_fops = { |
730 | .open = memory_open, |
731 | .llseek = noop_llseek, |
732 | }; |
733 | |
734 | static char *mem_devnode(const struct device *dev, umode_t *mode) |
735 | { |
736 | if (mode && devlist[MINOR(dev->devt)].mode) |
737 | *mode = devlist[MINOR(dev->devt)].mode; |
738 | return NULL; |
739 | } |
740 | |
741 | static const struct class mem_class = { |
742 | .name = "mem", |
743 | .devnode = mem_devnode, |
744 | }; |
745 | |
746 | static int __init chr_dev_init(void) |
747 | { |
748 | int retval; |
749 | int minor; |
750 | |
751 | if (register_chrdev(MEM_MAJOR, name: "mem", fops: &memory_fops)) |
752 | printk("unable to get major %d for memory devs\n", MEM_MAJOR); |
753 | |
754 | retval = class_register(class: &mem_class); |
755 | if (retval) |
756 | return retval; |
757 | |
758 | for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { |
759 | if (!devlist[minor].name) |
760 | continue; |
761 | |
762 | /* |
763 | * Create /dev/port? |
764 | */ |
765 | if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) |
766 | continue; |
767 | |
768 | device_create(cls: &mem_class, NULL, MKDEV(MEM_MAJOR, minor), |
769 | NULL, fmt: devlist[minor].name); |
770 | } |
771 | |
772 | return tty_init(); |
773 | } |
774 | |
775 | fs_initcall(chr_dev_init); |
776 |
Definitions
- size_inside_page
- page_is_allowed
- range_is_allowed
- should_stop_iteration
- read_mem
- write_mem
- phys_mem_access_prot_allowed
- private_mapping_ok
- mmap_mem_ops
- mmap_mem
- read_port
- write_port
- read_null
- write_null
- read_iter_null
- write_iter_null
- pipe_to_null
- splice_write_null
- uring_cmd_null
- read_iter_zero
- read_zero
- mmap_zero
- get_unmapped_area_zero
- write_full
- null_lseek
- memory_lseek
- open_port
- mem_fops
- null_fops
- port_fops
- zero_fops
- full_fops
- memdev
- devlist
- memory_open
- memory_fops
- mem_devnode
- mem_class
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