Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/drivers/char/mem.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | * | |
d7d4d849 | 7 | * Added devfs support. |
1da177e4 | 8 | * Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu> |
af901ca1 | 9 | * Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com> |
1da177e4 LT |
10 | */ |
11 | ||
1da177e4 LT |
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> | |
1da177e4 LT |
19 | #include <linux/tty.h> |
20 | #include <linux/capability.h> | |
1da177e4 LT |
21 | #include <linux/ptrace.h> |
22 | #include <linux/device.h> | |
50b1fdbd | 23 | #include <linux/highmem.h> |
1da177e4 | 24 | #include <linux/backing-dev.h> |
c01d5b30 | 25 | #include <linux/shmem_fs.h> |
d6b29d7c | 26 | #include <linux/splice.h> |
b8a3ad5b | 27 | #include <linux/pfn.h> |
66300e66 | 28 | #include <linux/export.h> |
e1612de9 | 29 | #include <linux/io.h> |
e2e40f2c | 30 | #include <linux/uio.h> |
35b6c7e4 | 31 | #include <linux/uaccess.h> |
9b9d8dda | 32 | #include <linux/security.h> |
1da177e4 | 33 | |
3234ac66 | 34 | #define DEVMEM_MINOR 1 |
e1612de9 HM |
35 | #define DEVPORT_MINOR 4 |
36 | ||
f222318e WF |
37 | static inline unsigned long size_inside_page(unsigned long start, |
38 | unsigned long size) | |
39 | { | |
40 | unsigned long sz; | |
41 | ||
7fabaddd | 42 | sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); |
f222318e | 43 | |
7fabaddd | 44 | return min(sz, size); |
f222318e WF |
45 | } |
46 | ||
1da177e4 | 47 | #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE |
7e6735c3 | 48 | static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) |
1da177e4 | 49 | { |
cfaf346c | 50 | return addr + count <= __pa(high_memory); |
1da177e4 | 51 | } |
80851ef2 | 52 | |
06c67bef | 53 | static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) |
80851ef2 BH |
54 | { |
55 | return 1; | |
56 | } | |
1da177e4 LT |
57 | #endif |
58 | ||
d092633b | 59 | #ifdef CONFIG_STRICT_DEVMEM |
a4866aa8 KC |
60 | static inline int page_is_allowed(unsigned long pfn) |
61 | { | |
62 | return devmem_is_allowed(pfn); | |
63 | } | |
e2beb3ea | 64 | static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
ae531c26 | 65 | { |
e2beb3ea VP |
66 | u64 from = ((u64)pfn) << PAGE_SHIFT; |
67 | u64 to = from + size; | |
68 | u64 cursor = from; | |
69 | ||
70 | while (cursor < to) { | |
39380b80 | 71 | if (!devmem_is_allowed(pfn)) |
ae531c26 | 72 | return 0; |
e2beb3ea VP |
73 | cursor += PAGE_SIZE; |
74 | pfn++; | |
ae531c26 AV |
75 | } |
76 | return 1; | |
77 | } | |
78 | #else | |
a4866aa8 KC |
79 | static inline int page_is_allowed(unsigned long pfn) |
80 | { | |
81 | return 1; | |
82 | } | |
e2beb3ea | 83 | static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
ae531c26 AV |
84 | { |
85 | return 1; | |
86 | } | |
87 | #endif | |
88 | ||
8619e5bd TH |
89 | static inline bool should_stop_iteration(void) |
90 | { | |
91 | if (need_resched()) | |
92 | cond_resched(); | |
830a4e5c | 93 | return signal_pending(current); |
8619e5bd TH |
94 | } |
95 | ||
1da177e4 | 96 | /* |
d7d4d849 AM |
97 | * This funcion reads the *physical* memory. The f_pos points directly to the |
98 | * memory location. | |
1da177e4 | 99 | */ |
d7d4d849 | 100 | static ssize_t read_mem(struct file *file, char __user *buf, |
1da177e4 LT |
101 | size_t count, loff_t *ppos) |
102 | { | |
7e6735c3 | 103 | phys_addr_t p = *ppos; |
1da177e4 | 104 | ssize_t read, sz; |
4707a341 | 105 | void *ptr; |
22ec1a2a KC |
106 | char *bounce; |
107 | int err; | |
1da177e4 | 108 | |
08d2d00b PT |
109 | if (p != *ppos) |
110 | return 0; | |
111 | ||
136939a2 | 112 | if (!valid_phys_addr_range(p, count)) |
1da177e4 LT |
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) { | |
7fabaddd | 118 | sz = size_inside_page(p, count); |
1da177e4 LT |
119 | if (sz > 0) { |
120 | if (clear_user(buf, sz)) | |
121 | return -EFAULT; | |
d7d4d849 AM |
122 | buf += sz; |
123 | p += sz; | |
124 | count -= sz; | |
125 | read += sz; | |
1da177e4 LT |
126 | } |
127 | } | |
128 | #endif | |
129 | ||
22ec1a2a KC |
130 | bounce = kmalloc(PAGE_SIZE, GFP_KERNEL); |
131 | if (!bounce) | |
132 | return -ENOMEM; | |
133 | ||
1da177e4 | 134 | while (count > 0) { |
fa29e97b | 135 | unsigned long remaining; |
b5b38200 | 136 | int allowed, probe; |
fa29e97b | 137 | |
f222318e | 138 | sz = size_inside_page(p, count); |
1da177e4 | 139 | |
22ec1a2a | 140 | err = -EPERM; |
a4866aa8 KC |
141 | allowed = page_is_allowed(p >> PAGE_SHIFT); |
142 | if (!allowed) | |
22ec1a2a KC |
143 | goto failed; |
144 | ||
145 | err = -EFAULT; | |
a4866aa8 KC |
146 | if (allowed == 2) { |
147 | /* Show zeros for restricted memory. */ | |
148 | remaining = clear_user(buf, 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(p); | |
156 | if (!ptr) | |
22ec1a2a | 157 | goto failed; |
a4866aa8 | 158 | |
fe557319 | 159 | probe = copy_from_kernel_nofault(bounce, ptr, sz); |
a4866aa8 | 160 | unxlate_dev_mem_ptr(p, ptr); |
b5b38200 | 161 | if (probe) |
22ec1a2a KC |
162 | goto failed; |
163 | ||
164 | remaining = copy_to_user(buf, bounce, sz); | |
a4866aa8 | 165 | } |
1da177e4 | 166 | |
fa29e97b | 167 | if (remaining) |
22ec1a2a | 168 | goto failed; |
e045fb2a | 169 | |
1da177e4 LT |
170 | buf += sz; |
171 | p += sz; | |
172 | count -= sz; | |
173 | read += sz; | |
8619e5bd TH |
174 | if (should_stop_iteration()) |
175 | break; | |
1da177e4 | 176 | } |
22ec1a2a | 177 | kfree(bounce); |
1da177e4 LT |
178 | |
179 | *ppos += read; | |
180 | return read; | |
22ec1a2a KC |
181 | |
182 | failed: | |
183 | kfree(bounce); | |
184 | return err; | |
1da177e4 LT |
185 | } |
186 | ||
d7d4d849 | 187 | static ssize_t write_mem(struct file *file, const char __user *buf, |
1da177e4 LT |
188 | size_t count, loff_t *ppos) |
189 | { | |
7e6735c3 | 190 | phys_addr_t p = *ppos; |
1da177e4 LT |
191 | ssize_t written, sz; |
192 | unsigned long copied; | |
193 | void *ptr; | |
194 | ||
08d2d00b PT |
195 | if (p != *ppos) |
196 | return -EFBIG; | |
197 | ||
136939a2 | 198 | if (!valid_phys_addr_range(p, count)) |
1da177e4 LT |
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) { | |
7fabaddd | 206 | sz = size_inside_page(p, count); |
1da177e4 LT |
207 | /* Hmm. Do something? */ |
208 | buf += sz; | |
209 | p += sz; | |
210 | count -= sz; | |
211 | written += sz; | |
212 | } | |
213 | #endif | |
214 | ||
215 | while (count > 0) { | |
a4866aa8 KC |
216 | int allowed; |
217 | ||
f222318e | 218 | sz = size_inside_page(p, count); |
1da177e4 | 219 | |
a4866aa8 KC |
220 | allowed = page_is_allowed(p >> PAGE_SHIFT); |
221 | if (!allowed) | |
e045fb2a | 222 | return -EPERM; |
223 | ||
a4866aa8 KC |
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(p); | |
232 | if (!ptr) { | |
233 | if (written) | |
234 | break; | |
235 | return -EFAULT; | |
236 | } | |
237 | ||
238 | copied = copy_from_user(ptr, buf, sz); | |
239 | unxlate_dev_mem_ptr(p, ptr); | |
240 | if (copied) { | |
241 | written += sz - copied; | |
242 | if (written) | |
243 | break; | |
244 | return -EFAULT; | |
245 | } | |
1da177e4 | 246 | } |
e045fb2a | 247 | |
1da177e4 LT |
248 | buf += sz; |
249 | p += sz; | |
250 | count -= sz; | |
251 | written += sz; | |
8619e5bd TH |
252 | if (should_stop_iteration()) |
253 | break; | |
1da177e4 LT |
254 | } |
255 | ||
256 | *ppos += written; | |
257 | return written; | |
258 | } | |
259 | ||
d7d4d849 | 260 | int __weak phys_mem_access_prot_allowed(struct file *file, |
f0970c13 | 261 | unsigned long pfn, unsigned long size, pgprot_t *vma_prot) |
262 | { | |
263 | return 1; | |
264 | } | |
265 | ||
44ac8413 | 266 | #ifndef __HAVE_PHYS_MEM_ACCESS_PROT |
d7d4d849 AM |
267 | |
268 | /* | |
269 | * Architectures vary in how they handle caching for addresses | |
270 | * outside of main memory. | |
271 | * | |
272 | */ | |
ea56f411 | 273 | #ifdef pgprot_noncached |
7e6735c3 | 274 | static int uncached_access(struct file *file, phys_addr_t addr) |
d7d4d849 | 275 | { |
d7d4d849 AM |
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); | |
d7d4d849 | 284 | } |
ea56f411 | 285 | #endif |
d7d4d849 | 286 | |
44ac8413 BH |
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 | |
7e6735c3 | 291 | phys_addr_t offset = pfn << PAGE_SHIFT; |
44ac8413 BH |
292 | |
293 | if (uncached_access(file, offset)) | |
294 | return pgprot_noncached(vma_prot); | |
295 | #endif | |
296 | return vma_prot; | |
297 | } | |
298 | #endif | |
299 | ||
5da6185b DH |
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; | |
8a93258c | 309 | return pgoff << PAGE_SHIFT; |
5da6185b DH |
310 | } |
311 | ||
b4caecd4 CH |
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 | ||
5da6185b DH |
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 | { | |
fc4f4be9 | 327 | return is_nommu_shared_mapping(vma->vm_flags); |
5da6185b DH |
328 | } |
329 | #else | |
5da6185b DH |
330 | |
331 | static inline int private_mapping_ok(struct vm_area_struct *vma) | |
332 | { | |
333 | return 1; | |
334 | } | |
335 | #endif | |
336 | ||
f0f37e2f | 337 | static const struct vm_operations_struct mmap_mem_ops = { |
7ae8ed50 RR |
338 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
339 | .access = generic_access_phys | |
340 | #endif | |
e7f260a2 | 341 | }; |
342 | ||
d7d4d849 | 343 | static int mmap_mem(struct file *file, struct vm_area_struct *vma) |
1da177e4 | 344 | { |
80851ef2 | 345 | size_t size = vma->vm_end - vma->vm_start; |
b299cde2 JW |
346 | phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; |
347 | ||
be62a320 CB |
348 | /* Does it even fit in phys_addr_t? */ |
349 | if (offset >> PAGE_SHIFT != vma->vm_pgoff) | |
350 | return -EINVAL; | |
351 | ||
b299cde2 | 352 | /* It's illegal to wrap around the end of the physical address space. */ |
32829da5 | 353 | if (offset + (phys_addr_t)size - 1 < offset) |
b299cde2 | 354 | return -EINVAL; |
80851ef2 | 355 | |
06c67bef | 356 | if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) |
80851ef2 BH |
357 | return -EINVAL; |
358 | ||
5da6185b DH |
359 | if (!private_mapping_ok(vma)) |
360 | return -ENOSYS; | |
361 | ||
e2beb3ea VP |
362 | if (!range_is_allowed(vma->vm_pgoff, size)) |
363 | return -EPERM; | |
364 | ||
f0970c13 | 365 | if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, |
366 | &vma->vm_page_prot)) | |
367 | return -EINVAL; | |
368 | ||
8b150478 | 369 | vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, |
80851ef2 | 370 | size, |
1da177e4 | 371 | vma->vm_page_prot); |
1da177e4 | 372 | |
e7f260a2 | 373 | vma->vm_ops = &mmap_mem_ops; |
374 | ||
314e51b9 | 375 | /* Remap-pfn-range will mark the range VM_IO */ |
1da177e4 LT |
376 | if (remap_pfn_range(vma, |
377 | vma->vm_start, | |
378 | vma->vm_pgoff, | |
80851ef2 | 379 | size, |
e7f260a2 | 380 | vma->vm_page_prot)) { |
1da177e4 | 381 | return -EAGAIN; |
e7f260a2 | 382 | } |
1da177e4 LT |
383 | return 0; |
384 | } | |
385 | ||
d7d4d849 | 386 | static ssize_t read_port(struct file *file, char __user *buf, |
1da177e4 LT |
387 | size_t count, loff_t *ppos) |
388 | { | |
389 | unsigned long i = *ppos; | |
390 | char __user *tmp = buf; | |
391 | ||
96d4f267 | 392 | if (!access_ok(buf, count)) |
d7d4d849 | 393 | return -EFAULT; |
1da177e4 | 394 | while (count-- > 0 && i < 65536) { |
d7d4d849 AM |
395 | if (__put_user(inb(i), tmp) < 0) |
396 | return -EFAULT; | |
1da177e4 LT |
397 | i++; |
398 | tmp++; | |
399 | } | |
400 | *ppos = i; | |
401 | return tmp-buf; | |
402 | } | |
403 | ||
d7d4d849 | 404 | static ssize_t write_port(struct file *file, const char __user *buf, |
1da177e4 LT |
405 | size_t count, loff_t *ppos) |
406 | { | |
407 | unsigned long i = *ppos; | |
890537b3 | 408 | const char __user *tmp = buf; |
1da177e4 | 409 | |
96d4f267 | 410 | if (!access_ok(buf, count)) |
1da177e4 LT |
411 | return -EFAULT; |
412 | while (count-- > 0 && i < 65536) { | |
413 | char c; | |
6a0061ba | 414 | |
c654d60e JB |
415 | if (__get_user(c, tmp)) { |
416 | if (tmp > buf) | |
417 | break; | |
d7d4d849 | 418 | return -EFAULT; |
c654d60e | 419 | } |
d7d4d849 | 420 | outb(c, i); |
1da177e4 LT |
421 | i++; |
422 | tmp++; | |
423 | } | |
424 | *ppos = i; | |
425 | return tmp-buf; | |
426 | } | |
1da177e4 | 427 | |
d7d4d849 | 428 | static ssize_t read_null(struct file *file, char __user *buf, |
1da177e4 LT |
429 | size_t count, loff_t *ppos) |
430 | { | |
431 | return 0; | |
432 | } | |
433 | ||
d7d4d849 | 434 | static ssize_t write_null(struct file *file, const char __user *buf, |
1da177e4 LT |
435 | size_t count, loff_t *ppos) |
436 | { | |
437 | return count; | |
438 | } | |
439 | ||
cd28e28d | 440 | static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to) |
162934de ZB |
441 | { |
442 | return 0; | |
443 | } | |
444 | ||
cd28e28d | 445 | static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from) |
162934de | 446 | { |
cd28e28d AV |
447 | size_t count = iov_iter_count(from); |
448 | iov_iter_advance(from, count); | |
449 | return count; | |
162934de ZB |
450 | } |
451 | ||
1ebd32fc JA |
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 | ||
d7d4d849 | 458 | static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, |
1ebd32fc JA |
459 | loff_t *ppos, size_t len, unsigned int flags) |
460 | { | |
461 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); | |
462 | } | |
463 | ||
70752795 PM |
464 | static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags) |
465 | { | |
466 | return 0; | |
467 | } | |
468 | ||
13ba33e8 | 469 | static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter) |
1da177e4 | 470 | { |
13ba33e8 | 471 | size_t written = 0; |
1da177e4 | 472 | |
13ba33e8 AV |
473 | while (iov_iter_count(iter)) { |
474 | size_t chunk = iov_iter_count(iter), n; | |
6a0061ba | 475 | |
557ed1fa NP |
476 | if (chunk > PAGE_SIZE) |
477 | chunk = PAGE_SIZE; /* Just for latency reasons */ | |
13ba33e8 AV |
478 | n = iov_iter_zero(chunk, iter); |
479 | if (!n && iov_iter_count(iter)) | |
480 | return written ? written : -EFAULT; | |
481 | written += n; | |
2b838687 LT |
482 | if (signal_pending(current)) |
483 | return written ? written : -ERESTARTSYS; | |
e5f71d60 PB |
484 | if (!need_resched()) |
485 | continue; | |
486 | if (iocb->ki_flags & IOCB_NOWAIT) | |
487 | return written ? written : -EAGAIN; | |
1da177e4 LT |
488 | cond_resched(); |
489 | } | |
13ba33e8 | 490 | return written; |
162934de ZB |
491 | } |
492 | ||
99f66735 CH |
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); | |
ab04de8e | 500 | size_t left; |
99f66735 | 501 | |
ab04de8e CH |
502 | left = clear_user(buf + cleared, chunk); |
503 | if (unlikely(left)) { | |
504 | cleared += (chunk - left); | |
505 | if (!cleared) | |
506 | return -EFAULT; | |
507 | break; | |
508 | } | |
99f66735 CH |
509 | cleared += chunk; |
510 | count -= chunk; | |
511 | ||
512 | if (signal_pending(current)) | |
ab04de8e | 513 | break; |
99f66735 CH |
514 | cond_resched(); |
515 | } | |
516 | ||
517 | return cleared; | |
518 | } | |
519 | ||
d7d4d849 | 520 | static int mmap_zero(struct file *file, struct vm_area_struct *vma) |
1da177e4 | 521 | { |
557ed1fa | 522 | #ifndef CONFIG_MMU |
1da177e4 | 523 | return -ENOSYS; |
557ed1fa NP |
524 | #endif |
525 | if (vma->vm_flags & VM_SHARED) | |
526 | return shmem_zero_setup(vma); | |
bfd40eaf | 527 | vma_set_anonymous(vma); |
557ed1fa | 528 | return 0; |
1da177e4 | 529 | } |
1da177e4 | 530 | |
c01d5b30 HD |
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 | ||
d7d4d849 | 553 | static ssize_t write_full(struct file *file, const char __user *buf, |
1da177e4 LT |
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 | */ | |
d7d4d849 | 564 | static loff_t null_lseek(struct file *file, loff_t offset, int orig) |
1da177e4 LT |
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 | */ | |
d7d4d849 | 577 | static loff_t memory_lseek(struct file *file, loff_t offset, int orig) |
1da177e4 LT |
578 | { |
579 | loff_t ret; | |
580 | ||
5955102c | 581 | inode_lock(file_inode(file)); |
1da177e4 | 582 | switch (orig) { |
d7d4d849 AM |
583 | case SEEK_CUR: |
584 | offset += file->f_pos; | |
df561f66 | 585 | fallthrough; |
d7d4d849 AM |
586 | case SEEK_SET: |
587 | /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ | |
ecb63a1b | 588 | if ((unsigned long long)offset >= -MAX_ERRNO) { |
d7d4d849 | 589 | ret = -EOVERFLOW; |
1da177e4 | 590 | break; |
d7d4d849 AM |
591 | } |
592 | file->f_pos = offset; | |
593 | ret = file->f_pos; | |
594 | force_successful_syscall_return(); | |
595 | break; | |
596 | default: | |
597 | ret = -EINVAL; | |
1da177e4 | 598 | } |
5955102c | 599 | inode_unlock(file_inode(file)); |
1da177e4 LT |
600 | return ret; |
601 | } | |
602 | ||
890537b3 | 603 | static int open_port(struct inode *inode, struct file *filp) |
1da177e4 | 604 | { |
3234ac66 DW |
605 | int rc; |
606 | ||
9b9d8dda MG |
607 | if (!capable(CAP_SYS_RAWIO)) |
608 | return -EPERM; | |
609 | ||
3234ac66 DW |
610 | rc = security_locked_down(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 | */ | |
71a1d8ed | 622 | filp->f_mapping = iomem_get_mapping(); |
3234ac66 DW |
623 | |
624 | return 0; | |
1da177e4 LT |
625 | } |
626 | ||
627 | #define zero_lseek null_lseek | |
628 | #define full_lseek null_lseek | |
629 | #define write_zero write_null | |
cd28e28d | 630 | #define write_iter_zero write_iter_null |
1b057bd8 | 631 | #define splice_write_zero splice_write_null |
1da177e4 | 632 | #define open_mem open_port |
1da177e4 | 633 | |
73f0718e | 634 | static const struct file_operations __maybe_unused mem_fops = { |
1da177e4 LT |
635 | .llseek = memory_lseek, |
636 | .read = read_mem, | |
637 | .write = write_mem, | |
638 | .mmap = mmap_mem, | |
639 | .open = open_mem, | |
b4caecd4 | 640 | #ifndef CONFIG_MMU |
5da6185b | 641 | .get_unmapped_area = get_unmapped_area_mem, |
b4caecd4 CH |
642 | .mmap_capabilities = memory_mmap_capabilities, |
643 | #endif | |
1da177e4 LT |
644 | }; |
645 | ||
62322d25 | 646 | static const struct file_operations null_fops = { |
1da177e4 LT |
647 | .llseek = null_lseek, |
648 | .read = read_null, | |
649 | .write = write_null, | |
cd28e28d AV |
650 | .read_iter = read_iter_null, |
651 | .write_iter = write_iter_null, | |
1ebd32fc | 652 | .splice_write = splice_write_null, |
70752795 | 653 | .uring_cmd = uring_cmd_null, |
1da177e4 LT |
654 | }; |
655 | ||
3a4bc2fb | 656 | static const struct file_operations __maybe_unused port_fops = { |
1da177e4 LT |
657 | .llseek = memory_lseek, |
658 | .read = read_port, | |
659 | .write = write_port, | |
660 | .open = open_port, | |
661 | }; | |
1da177e4 | 662 | |
62322d25 | 663 | static const struct file_operations zero_fops = { |
1da177e4 | 664 | .llseek = zero_lseek, |
1da177e4 | 665 | .write = write_zero, |
13ba33e8 | 666 | .read_iter = read_iter_zero, |
99f66735 | 667 | .read = read_zero, |
cd28e28d | 668 | .write_iter = write_iter_zero, |
1b057bd8 MK |
669 | .splice_read = copy_splice_read, |
670 | .splice_write = splice_write_zero, | |
1da177e4 | 671 | .mmap = mmap_zero, |
c01d5b30 | 672 | .get_unmapped_area = get_unmapped_area_zero, |
b4caecd4 CH |
673 | #ifndef CONFIG_MMU |
674 | .mmap_capabilities = zero_mmap_capabilities, | |
675 | #endif | |
1da177e4 LT |
676 | }; |
677 | ||
62322d25 | 678 | static const struct file_operations full_fops = { |
1da177e4 | 679 | .llseek = full_lseek, |
13ba33e8 | 680 | .read_iter = read_iter_zero, |
1da177e4 | 681 | .write = write_full, |
1b057bd8 | 682 | .splice_read = copy_splice_read, |
1da177e4 LT |
683 | }; |
684 | ||
389e0cb9 KS |
685 | static const struct memdev { |
686 | const char *name; | |
687 | const struct file_operations *fops; | |
b4caecd4 | 688 | fmode_t fmode; |
ed1af26c | 689 | umode_t mode; |
389e0cb9 | 690 | } devlist[] = { |
73f0718e | 691 | #ifdef CONFIG_DEVMEM |
ed1af26c | 692 | [DEVMEM_MINOR] = { "mem", &mem_fops, FMODE_UNSIGNED_OFFSET, 0 }, |
b781ecb6 | 693 | #endif |
ed1af26c | 694 | [3] = { "null", &null_fops, FMODE_NOWAIT, 0666 }, |
4f911d64 | 695 | #ifdef CONFIG_DEVPORT |
ed1af26c | 696 | [4] = { "port", &port_fops, 0, 0 }, |
1da177e4 | 697 | #endif |
ed1af26c AD |
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 }, | |
7f3a781d | 702 | #ifdef CONFIG_PRINTK |
ed1af26c | 703 | [11] = { "kmsg", &kmsg_fops, 0, 0644 }, |
7f3a781d | 704 | #endif |
d6f47bef ASF |
705 | }; |
706 | ||
707 | static int memory_open(struct inode *inode, struct file *filp) | |
708 | { | |
389e0cb9 KS |
709 | int minor; |
710 | const struct memdev *dev; | |
d6f47bef | 711 | |
389e0cb9 KS |
712 | minor = iminor(inode); |
713 | if (minor >= ARRAY_SIZE(devlist)) | |
205153aa | 714 | return -ENXIO; |
d6f47bef | 715 | |
389e0cb9 KS |
716 | dev = &devlist[minor]; |
717 | if (!dev->fops) | |
205153aa | 718 | return -ENXIO; |
d6f47bef | 719 | |
389e0cb9 | 720 | filp->f_op = dev->fops; |
b4caecd4 | 721 | filp->f_mode |= dev->fmode; |
4a3956c7 | 722 | |
389e0cb9 | 723 | if (dev->fops->open) |
205153aa FW |
724 | return dev->fops->open(inode, filp); |
725 | ||
726 | return 0; | |
1da177e4 LT |
727 | } |
728 | ||
62322d25 | 729 | static const struct file_operations memory_fops = { |
d7d4d849 | 730 | .open = memory_open, |
6038f373 | 731 | .llseek = noop_llseek, |
1da177e4 LT |
732 | }; |
733 | ||
ff62b8e6 | 734 | static char *mem_devnode(const struct device *dev, umode_t *mode) |
e454cea2 KS |
735 | { |
736 | if (mode && devlist[MINOR(dev->devt)].mode) | |
737 | *mode = devlist[MINOR(dev->devt)].mode; | |
738 | return NULL; | |
739 | } | |
740 | ||
7671284b IO |
741 | static const struct class mem_class = { |
742 | .name = "mem", | |
743 | .devnode = mem_devnode, | |
744 | }; | |
1da177e4 LT |
745 | |
746 | static int __init chr_dev_init(void) | |
747 | { | |
7671284b | 748 | int retval; |
389e0cb9 | 749 | int minor; |
1da177e4 | 750 | |
d7d4d849 | 751 | if (register_chrdev(MEM_MAJOR, "mem", &memory_fops)) |
1da177e4 LT |
752 | printk("unable to get major %d for memory devs\n", MEM_MAJOR); |
753 | ||
7671284b IO |
754 | retval = class_register(&mem_class); |
755 | if (retval) | |
756 | return retval; | |
6e191f7b | 757 | |
389e0cb9 KS |
758 | for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { |
759 | if (!devlist[minor].name) | |
760 | continue; | |
e1612de9 HM |
761 | |
762 | /* | |
890537b3 | 763 | * Create /dev/port? |
e1612de9 HM |
764 | */ |
765 | if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) | |
766 | continue; | |
767 | ||
7671284b | 768 | device_create(&mem_class, NULL, MKDEV(MEM_MAJOR, minor), |
389e0cb9 KS |
769 | NULL, devlist[minor].name); |
770 | } | |
ebf644c4 | 771 | |
31d1d48e | 772 | return tty_init(); |
1da177e4 LT |
773 | } |
774 | ||
775 | fs_initcall(chr_dev_init); |