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 LT |
33 | |
34 | #ifdef CONFIG_IA64 | |
35 | # include <linux/efi.h> | |
36 | #endif | |
37 | ||
3234ac66 | 38 | #define DEVMEM_MINOR 1 |
e1612de9 HM |
39 | #define DEVPORT_MINOR 4 |
40 | ||
f222318e WF |
41 | static inline unsigned long size_inside_page(unsigned long start, |
42 | unsigned long size) | |
43 | { | |
44 | unsigned long sz; | |
45 | ||
7fabaddd | 46 | sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); |
f222318e | 47 | |
7fabaddd | 48 | return min(sz, size); |
f222318e WF |
49 | } |
50 | ||
1da177e4 | 51 | #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE |
7e6735c3 | 52 | static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) |
1da177e4 | 53 | { |
cfaf346c | 54 | return addr + count <= __pa(high_memory); |
1da177e4 | 55 | } |
80851ef2 | 56 | |
06c67bef | 57 | static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) |
80851ef2 BH |
58 | { |
59 | return 1; | |
60 | } | |
1da177e4 LT |
61 | #endif |
62 | ||
d092633b | 63 | #ifdef CONFIG_STRICT_DEVMEM |
a4866aa8 KC |
64 | static inline int page_is_allowed(unsigned long pfn) |
65 | { | |
66 | return devmem_is_allowed(pfn); | |
67 | } | |
e2beb3ea | 68 | static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
ae531c26 | 69 | { |
e2beb3ea VP |
70 | u64 from = ((u64)pfn) << PAGE_SHIFT; |
71 | u64 to = from + size; | |
72 | u64 cursor = from; | |
73 | ||
74 | while (cursor < to) { | |
39380b80 | 75 | if (!devmem_is_allowed(pfn)) |
ae531c26 | 76 | return 0; |
e2beb3ea VP |
77 | cursor += PAGE_SIZE; |
78 | pfn++; | |
ae531c26 AV |
79 | } |
80 | return 1; | |
81 | } | |
82 | #else | |
a4866aa8 KC |
83 | static inline int page_is_allowed(unsigned long pfn) |
84 | { | |
85 | return 1; | |
86 | } | |
e2beb3ea | 87 | static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
ae531c26 AV |
88 | { |
89 | return 1; | |
90 | } | |
91 | #endif | |
92 | ||
4707a341 TR |
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) | |
e045fb2a | 96 | { |
97 | } | |
4707a341 | 98 | #endif |
e045fb2a | 99 | |
8619e5bd TH |
100 | static inline bool should_stop_iteration(void) |
101 | { | |
102 | if (need_resched()) | |
103 | cond_resched(); | |
830a4e5c | 104 | return signal_pending(current); |
8619e5bd TH |
105 | } |
106 | ||
1da177e4 | 107 | /* |
d7d4d849 AM |
108 | * This funcion reads the *physical* memory. The f_pos points directly to the |
109 | * memory location. | |
1da177e4 | 110 | */ |
d7d4d849 | 111 | static ssize_t read_mem(struct file *file, char __user *buf, |
1da177e4 LT |
112 | size_t count, loff_t *ppos) |
113 | { | |
7e6735c3 | 114 | phys_addr_t p = *ppos; |
1da177e4 | 115 | ssize_t read, sz; |
4707a341 | 116 | void *ptr; |
22ec1a2a KC |
117 | char *bounce; |
118 | int err; | |
1da177e4 | 119 | |
08d2d00b PT |
120 | if (p != *ppos) |
121 | return 0; | |
122 | ||
136939a2 | 123 | if (!valid_phys_addr_range(p, count)) |
1da177e4 LT |
124 | return -EFAULT; |
125 | 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) { | |
7fabaddd | 129 | sz = size_inside_page(p, count); |
1da177e4 LT |
130 | if (sz > 0) { |
131 | if (clear_user(buf, sz)) | |
132 | return -EFAULT; | |
d7d4d849 AM |
133 | buf += sz; |
134 | p += sz; | |
135 | count -= sz; | |
136 | read += sz; | |
1da177e4 LT |
137 | } |
138 | } | |
139 | #endif | |
140 | ||
22ec1a2a KC |
141 | bounce = kmalloc(PAGE_SIZE, GFP_KERNEL); |
142 | if (!bounce) | |
143 | return -ENOMEM; | |
144 | ||
1da177e4 | 145 | while (count > 0) { |
fa29e97b | 146 | unsigned long remaining; |
b5b38200 | 147 | int allowed, probe; |
fa29e97b | 148 | |
f222318e | 149 | sz = size_inside_page(p, count); |
1da177e4 | 150 | |
22ec1a2a | 151 | err = -EPERM; |
a4866aa8 KC |
152 | allowed = page_is_allowed(p >> PAGE_SHIFT); |
153 | if (!allowed) | |
22ec1a2a KC |
154 | goto failed; |
155 | ||
156 | err = -EFAULT; | |
a4866aa8 KC |
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 | ptr = xlate_dev_mem_ptr(p); | |
167 | if (!ptr) | |
22ec1a2a | 168 | goto failed; |
a4866aa8 | 169 | |
fe557319 | 170 | probe = copy_from_kernel_nofault(bounce, ptr, sz); |
a4866aa8 | 171 | unxlate_dev_mem_ptr(p, ptr); |
b5b38200 | 172 | if (probe) |
22ec1a2a KC |
173 | goto failed; |
174 | ||
175 | remaining = copy_to_user(buf, bounce, sz); | |
a4866aa8 | 176 | } |
1da177e4 | 177 | |
fa29e97b | 178 | if (remaining) |
22ec1a2a | 179 | goto failed; |
e045fb2a | 180 | |
1da177e4 LT |
181 | buf += sz; |
182 | p += sz; | |
183 | count -= sz; | |
184 | read += sz; | |
8619e5bd TH |
185 | if (should_stop_iteration()) |
186 | break; | |
1da177e4 | 187 | } |
22ec1a2a | 188 | kfree(bounce); |
1da177e4 LT |
189 | |
190 | *ppos += read; | |
191 | return read; | |
22ec1a2a KC |
192 | |
193 | failed: | |
194 | kfree(bounce); | |
195 | return err; | |
1da177e4 LT |
196 | } |
197 | ||
d7d4d849 | 198 | static ssize_t write_mem(struct file *file, const char __user *buf, |
1da177e4 LT |
199 | size_t count, loff_t *ppos) |
200 | { | |
7e6735c3 | 201 | phys_addr_t p = *ppos; |
1da177e4 LT |
202 | ssize_t written, sz; |
203 | unsigned long copied; | |
204 | void *ptr; | |
205 | ||
08d2d00b PT |
206 | if (p != *ppos) |
207 | return -EFBIG; | |
208 | ||
136939a2 | 209 | if (!valid_phys_addr_range(p, count)) |
1da177e4 LT |
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) { | |
7fabaddd | 217 | sz = size_inside_page(p, count); |
1da177e4 LT |
218 | /* Hmm. Do something? */ |
219 | buf += sz; | |
220 | p += sz; | |
221 | count -= sz; | |
222 | written += sz; | |
223 | } | |
224 | #endif | |
225 | ||
226 | while (count > 0) { | |
a4866aa8 KC |
227 | int allowed; |
228 | ||
f222318e | 229 | sz = size_inside_page(p, count); |
1da177e4 | 230 | |
a4866aa8 KC |
231 | allowed = page_is_allowed(p >> PAGE_SHIFT); |
232 | if (!allowed) | |
e045fb2a | 233 | return -EPERM; |
234 | ||
a4866aa8 KC |
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 | ptr = xlate_dev_mem_ptr(p); | |
243 | if (!ptr) { | |
244 | if (written) | |
245 | break; | |
246 | return -EFAULT; | |
247 | } | |
248 | ||
249 | copied = copy_from_user(ptr, buf, sz); | |
250 | unxlate_dev_mem_ptr(p, ptr); | |
251 | if (copied) { | |
252 | written += sz - copied; | |
253 | if (written) | |
254 | break; | |
255 | return -EFAULT; | |
256 | } | |
1da177e4 | 257 | } |
e045fb2a | 258 | |
1da177e4 LT |
259 | buf += sz; |
260 | p += sz; | |
261 | count -= sz; | |
262 | written += sz; | |
8619e5bd TH |
263 | if (should_stop_iteration()) |
264 | break; | |
1da177e4 LT |
265 | } |
266 | ||
267 | *ppos += written; | |
268 | return written; | |
269 | } | |
270 | ||
d7d4d849 | 271 | int __weak phys_mem_access_prot_allowed(struct file *file, |
f0970c13 | 272 | unsigned long pfn, unsigned long size, pgprot_t *vma_prot) |
273 | { | |
274 | return 1; | |
275 | } | |
276 | ||
44ac8413 | 277 | #ifndef __HAVE_PHYS_MEM_ACCESS_PROT |
d7d4d849 AM |
278 | |
279 | /* | |
280 | * Architectures vary in how they handle caching for addresses | |
281 | * outside of main memory. | |
282 | * | |
283 | */ | |
ea56f411 | 284 | #ifdef pgprot_noncached |
7e6735c3 | 285 | static int uncached_access(struct file *file, phys_addr_t addr) |
d7d4d849 AM |
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); | |
d7d4d849 AM |
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 | } | |
ea56f411 | 304 | #endif |
d7d4d849 | 305 | |
44ac8413 BH |
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 | |
7e6735c3 | 310 | phys_addr_t offset = pfn << PAGE_SHIFT; |
44ac8413 BH |
311 | |
312 | if (uncached_access(file, offset)) | |
313 | return pgprot_noncached(vma_prot); | |
314 | #endif | |
315 | return vma_prot; | |
316 | } | |
317 | #endif | |
318 | ||
5da6185b DH |
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; | |
8a93258c | 328 | return pgoff << PAGE_SHIFT; |
5da6185b DH |
329 | } |
330 | ||
b4caecd4 CH |
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 | ||
5da6185b DH |
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 vma->vm_flags & VM_MAYSHARE; | |
347 | } | |
348 | #else | |
5da6185b DH |
349 | |
350 | static inline int private_mapping_ok(struct vm_area_struct *vma) | |
351 | { | |
352 | return 1; | |
353 | } | |
354 | #endif | |
355 | ||
f0f37e2f | 356 | static const struct vm_operations_struct mmap_mem_ops = { |
7ae8ed50 RR |
357 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
358 | .access = generic_access_phys | |
359 | #endif | |
e7f260a2 | 360 | }; |
361 | ||
d7d4d849 | 362 | static int mmap_mem(struct file *file, struct vm_area_struct *vma) |
1da177e4 | 363 | { |
80851ef2 | 364 | size_t size = vma->vm_end - vma->vm_start; |
b299cde2 JW |
365 | phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; |
366 | ||
be62a320 CB |
367 | /* Does it even fit in phys_addr_t? */ |
368 | if (offset >> PAGE_SHIFT != vma->vm_pgoff) | |
369 | return -EINVAL; | |
370 | ||
b299cde2 | 371 | /* It's illegal to wrap around the end of the physical address space. */ |
32829da5 | 372 | if (offset + (phys_addr_t)size - 1 < offset) |
b299cde2 | 373 | return -EINVAL; |
80851ef2 | 374 | |
06c67bef | 375 | if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) |
80851ef2 BH |
376 | return -EINVAL; |
377 | ||
5da6185b DH |
378 | if (!private_mapping_ok(vma)) |
379 | return -ENOSYS; | |
380 | ||
e2beb3ea VP |
381 | if (!range_is_allowed(vma->vm_pgoff, size)) |
382 | return -EPERM; | |
383 | ||
f0970c13 | 384 | if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, |
385 | &vma->vm_page_prot)) | |
386 | return -EINVAL; | |
387 | ||
8b150478 | 388 | vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, |
80851ef2 | 389 | size, |
1da177e4 | 390 | vma->vm_page_prot); |
1da177e4 | 391 | |
e7f260a2 | 392 | vma->vm_ops = &mmap_mem_ops; |
393 | ||
314e51b9 | 394 | /* Remap-pfn-range will mark the range VM_IO */ |
1da177e4 LT |
395 | if (remap_pfn_range(vma, |
396 | vma->vm_start, | |
397 | vma->vm_pgoff, | |
80851ef2 | 398 | size, |
e7f260a2 | 399 | vma->vm_page_prot)) { |
1da177e4 | 400 | return -EAGAIN; |
e7f260a2 | 401 | } |
1da177e4 LT |
402 | return 0; |
403 | } | |
404 | ||
d7d4d849 | 405 | static ssize_t read_port(struct file *file, char __user *buf, |
1da177e4 LT |
406 | size_t count, loff_t *ppos) |
407 | { | |
408 | unsigned long i = *ppos; | |
409 | char __user *tmp = buf; | |
410 | ||
96d4f267 | 411 | if (!access_ok(buf, count)) |
d7d4d849 | 412 | return -EFAULT; |
1da177e4 | 413 | while (count-- > 0 && i < 65536) { |
d7d4d849 AM |
414 | if (__put_user(inb(i), tmp) < 0) |
415 | return -EFAULT; | |
1da177e4 LT |
416 | i++; |
417 | tmp++; | |
418 | } | |
419 | *ppos = i; | |
420 | return tmp-buf; | |
421 | } | |
422 | ||
d7d4d849 | 423 | static ssize_t write_port(struct file *file, const char __user *buf, |
1da177e4 LT |
424 | size_t count, loff_t *ppos) |
425 | { | |
426 | unsigned long i = *ppos; | |
890537b3 | 427 | const char __user *tmp = buf; |
1da177e4 | 428 | |
96d4f267 | 429 | if (!access_ok(buf, count)) |
1da177e4 LT |
430 | return -EFAULT; |
431 | while (count-- > 0 && i < 65536) { | |
432 | char c; | |
6a0061ba | 433 | |
c654d60e JB |
434 | if (__get_user(c, tmp)) { |
435 | if (tmp > buf) | |
436 | break; | |
d7d4d849 | 437 | return -EFAULT; |
c654d60e | 438 | } |
d7d4d849 | 439 | outb(c, i); |
1da177e4 LT |
440 | i++; |
441 | tmp++; | |
442 | } | |
443 | *ppos = i; | |
444 | return tmp-buf; | |
445 | } | |
1da177e4 | 446 | |
d7d4d849 | 447 | static ssize_t read_null(struct file *file, char __user *buf, |
1da177e4 LT |
448 | size_t count, loff_t *ppos) |
449 | { | |
450 | return 0; | |
451 | } | |
452 | ||
d7d4d849 | 453 | static ssize_t write_null(struct file *file, const char __user *buf, |
1da177e4 LT |
454 | size_t count, loff_t *ppos) |
455 | { | |
456 | return count; | |
457 | } | |
458 | ||
cd28e28d | 459 | static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to) |
162934de ZB |
460 | { |
461 | return 0; | |
462 | } | |
463 | ||
cd28e28d | 464 | static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from) |
162934de | 465 | { |
cd28e28d AV |
466 | size_t count = iov_iter_count(from); |
467 | iov_iter_advance(from, count); | |
468 | return count; | |
162934de ZB |
469 | } |
470 | ||
1ebd32fc JA |
471 | static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, |
472 | struct splice_desc *sd) | |
473 | { | |
474 | return sd->len; | |
475 | } | |
476 | ||
d7d4d849 | 477 | static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, |
1ebd32fc JA |
478 | loff_t *ppos, size_t len, unsigned int flags) |
479 | { | |
480 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); | |
481 | } | |
482 | ||
13ba33e8 | 483 | static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter) |
1da177e4 | 484 | { |
13ba33e8 | 485 | size_t written = 0; |
1da177e4 | 486 | |
13ba33e8 AV |
487 | while (iov_iter_count(iter)) { |
488 | size_t chunk = iov_iter_count(iter), n; | |
6a0061ba | 489 | |
557ed1fa NP |
490 | if (chunk > PAGE_SIZE) |
491 | chunk = PAGE_SIZE; /* Just for latency reasons */ | |
13ba33e8 AV |
492 | n = iov_iter_zero(chunk, iter); |
493 | if (!n && iov_iter_count(iter)) | |
494 | return written ? written : -EFAULT; | |
495 | written += n; | |
2b838687 LT |
496 | if (signal_pending(current)) |
497 | return written ? written : -ERESTARTSYS; | |
e5f71d60 PB |
498 | if (!need_resched()) |
499 | continue; | |
500 | if (iocb->ki_flags & IOCB_NOWAIT) | |
501 | return written ? written : -EAGAIN; | |
1da177e4 LT |
502 | cond_resched(); |
503 | } | |
13ba33e8 | 504 | return written; |
162934de ZB |
505 | } |
506 | ||
99f66735 CH |
507 | static ssize_t read_zero(struct file *file, char __user *buf, |
508 | size_t count, loff_t *ppos) | |
509 | { | |
510 | size_t cleared = 0; | |
511 | ||
512 | while (count) { | |
513 | size_t chunk = min_t(size_t, count, PAGE_SIZE); | |
ab04de8e | 514 | size_t left; |
99f66735 | 515 | |
ab04de8e CH |
516 | left = clear_user(buf + cleared, chunk); |
517 | if (unlikely(left)) { | |
518 | cleared += (chunk - left); | |
519 | if (!cleared) | |
520 | return -EFAULT; | |
521 | break; | |
522 | } | |
99f66735 CH |
523 | cleared += chunk; |
524 | count -= chunk; | |
525 | ||
526 | if (signal_pending(current)) | |
ab04de8e | 527 | break; |
99f66735 CH |
528 | cond_resched(); |
529 | } | |
530 | ||
531 | return cleared; | |
532 | } | |
533 | ||
d7d4d849 | 534 | static int mmap_zero(struct file *file, struct vm_area_struct *vma) |
1da177e4 | 535 | { |
557ed1fa | 536 | #ifndef CONFIG_MMU |
1da177e4 | 537 | return -ENOSYS; |
557ed1fa NP |
538 | #endif |
539 | if (vma->vm_flags & VM_SHARED) | |
540 | return shmem_zero_setup(vma); | |
bfd40eaf | 541 | vma_set_anonymous(vma); |
557ed1fa | 542 | return 0; |
1da177e4 | 543 | } |
1da177e4 | 544 | |
c01d5b30 HD |
545 | static unsigned long get_unmapped_area_zero(struct file *file, |
546 | unsigned long addr, unsigned long len, | |
547 | unsigned long pgoff, unsigned long flags) | |
548 | { | |
549 | #ifdef CONFIG_MMU | |
550 | if (flags & MAP_SHARED) { | |
551 | /* | |
552 | * mmap_zero() will call shmem_zero_setup() to create a file, | |
553 | * so use shmem's get_unmapped_area in case it can be huge; | |
554 | * and pass NULL for file as in mmap.c's get_unmapped_area(), | |
555 | * so as not to confuse shmem with our handle on "/dev/zero". | |
556 | */ | |
557 | return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags); | |
558 | } | |
559 | ||
560 | /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */ | |
561 | return current->mm->get_unmapped_area(file, addr, len, pgoff, flags); | |
562 | #else | |
563 | return -ENOSYS; | |
564 | #endif | |
565 | } | |
566 | ||
d7d4d849 | 567 | static ssize_t write_full(struct file *file, const char __user *buf, |
1da177e4 LT |
568 | size_t count, loff_t *ppos) |
569 | { | |
570 | return -ENOSPC; | |
571 | } | |
572 | ||
573 | /* | |
574 | * Special lseek() function for /dev/null and /dev/zero. Most notably, you | |
575 | * can fopen() both devices with "a" now. This was previously impossible. | |
576 | * -- SRB. | |
577 | */ | |
d7d4d849 | 578 | static loff_t null_lseek(struct file *file, loff_t offset, int orig) |
1da177e4 LT |
579 | { |
580 | return file->f_pos = 0; | |
581 | } | |
582 | ||
583 | /* | |
584 | * The memory devices use the full 32/64 bits of the offset, and so we cannot | |
585 | * check against negative addresses: they are ok. The return value is weird, | |
586 | * though, in that case (0). | |
587 | * | |
588 | * also note that seeking relative to the "end of file" isn't supported: | |
589 | * it has no meaning, so it returns -EINVAL. | |
590 | */ | |
d7d4d849 | 591 | static loff_t memory_lseek(struct file *file, loff_t offset, int orig) |
1da177e4 LT |
592 | { |
593 | loff_t ret; | |
594 | ||
5955102c | 595 | inode_lock(file_inode(file)); |
1da177e4 | 596 | switch (orig) { |
d7d4d849 AM |
597 | case SEEK_CUR: |
598 | offset += file->f_pos; | |
df561f66 | 599 | fallthrough; |
d7d4d849 AM |
600 | case SEEK_SET: |
601 | /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ | |
ecb63a1b | 602 | if ((unsigned long long)offset >= -MAX_ERRNO) { |
d7d4d849 | 603 | ret = -EOVERFLOW; |
1da177e4 | 604 | break; |
d7d4d849 AM |
605 | } |
606 | file->f_pos = offset; | |
607 | ret = file->f_pos; | |
608 | force_successful_syscall_return(); | |
609 | break; | |
610 | default: | |
611 | ret = -EINVAL; | |
1da177e4 | 612 | } |
5955102c | 613 | inode_unlock(file_inode(file)); |
1da177e4 LT |
614 | return ret; |
615 | } | |
616 | ||
890537b3 | 617 | static int open_port(struct inode *inode, struct file *filp) |
1da177e4 | 618 | { |
3234ac66 DW |
619 | int rc; |
620 | ||
9b9d8dda MG |
621 | if (!capable(CAP_SYS_RAWIO)) |
622 | return -EPERM; | |
623 | ||
3234ac66 DW |
624 | rc = security_locked_down(LOCKDOWN_DEV_MEM); |
625 | if (rc) | |
626 | return rc; | |
627 | ||
628 | if (iminor(inode) != DEVMEM_MINOR) | |
629 | return 0; | |
630 | ||
631 | /* | |
632 | * Use a unified address space to have a single point to manage | |
633 | * revocations when drivers want to take over a /dev/mem mapped | |
634 | * range. | |
635 | */ | |
71a1d8ed | 636 | filp->f_mapping = iomem_get_mapping(); |
3234ac66 DW |
637 | |
638 | return 0; | |
1da177e4 LT |
639 | } |
640 | ||
641 | #define zero_lseek null_lseek | |
642 | #define full_lseek null_lseek | |
643 | #define write_zero write_null | |
cd28e28d | 644 | #define write_iter_zero write_iter_null |
1da177e4 | 645 | #define open_mem open_port |
1da177e4 | 646 | |
73f0718e | 647 | static const struct file_operations __maybe_unused mem_fops = { |
1da177e4 LT |
648 | .llseek = memory_lseek, |
649 | .read = read_mem, | |
650 | .write = write_mem, | |
651 | .mmap = mmap_mem, | |
652 | .open = open_mem, | |
b4caecd4 | 653 | #ifndef CONFIG_MMU |
5da6185b | 654 | .get_unmapped_area = get_unmapped_area_mem, |
b4caecd4 CH |
655 | .mmap_capabilities = memory_mmap_capabilities, |
656 | #endif | |
1da177e4 LT |
657 | }; |
658 | ||
62322d25 | 659 | static const struct file_operations null_fops = { |
1da177e4 LT |
660 | .llseek = null_lseek, |
661 | .read = read_null, | |
662 | .write = write_null, | |
cd28e28d AV |
663 | .read_iter = read_iter_null, |
664 | .write_iter = write_iter_null, | |
1ebd32fc | 665 | .splice_write = splice_write_null, |
1da177e4 LT |
666 | }; |
667 | ||
3a4bc2fb | 668 | static const struct file_operations __maybe_unused port_fops = { |
1da177e4 LT |
669 | .llseek = memory_lseek, |
670 | .read = read_port, | |
671 | .write = write_port, | |
672 | .open = open_port, | |
673 | }; | |
1da177e4 | 674 | |
62322d25 | 675 | static const struct file_operations zero_fops = { |
1da177e4 | 676 | .llseek = zero_lseek, |
1da177e4 | 677 | .write = write_zero, |
13ba33e8 | 678 | .read_iter = read_iter_zero, |
99f66735 | 679 | .read = read_zero, |
cd28e28d | 680 | .write_iter = write_iter_zero, |
1da177e4 | 681 | .mmap = mmap_zero, |
c01d5b30 | 682 | .get_unmapped_area = get_unmapped_area_zero, |
b4caecd4 CH |
683 | #ifndef CONFIG_MMU |
684 | .mmap_capabilities = zero_mmap_capabilities, | |
685 | #endif | |
1da177e4 LT |
686 | }; |
687 | ||
62322d25 | 688 | static const struct file_operations full_fops = { |
1da177e4 | 689 | .llseek = full_lseek, |
13ba33e8 | 690 | .read_iter = read_iter_zero, |
1da177e4 LT |
691 | .write = write_full, |
692 | }; | |
693 | ||
389e0cb9 KS |
694 | static const struct memdev { |
695 | const char *name; | |
2c9ede55 | 696 | umode_t mode; |
389e0cb9 | 697 | const struct file_operations *fops; |
b4caecd4 | 698 | fmode_t fmode; |
389e0cb9 | 699 | } devlist[] = { |
73f0718e | 700 | #ifdef CONFIG_DEVMEM |
3234ac66 | 701 | [DEVMEM_MINOR] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET }, |
b781ecb6 | 702 | #endif |
e5f71d60 | 703 | [3] = { "null", 0666, &null_fops, FMODE_NOWAIT }, |
4f911d64 | 704 | #ifdef CONFIG_DEVPORT |
b4caecd4 | 705 | [4] = { "port", 0, &port_fops, 0 }, |
1da177e4 | 706 | #endif |
e5f71d60 | 707 | [5] = { "zero", 0666, &zero_fops, FMODE_NOWAIT }, |
b4caecd4 CH |
708 | [7] = { "full", 0666, &full_fops, 0 }, |
709 | [8] = { "random", 0666, &random_fops, 0 }, | |
0313bc27 | 710 | [9] = { "urandom", 0666, &urandom_fops, 0 }, |
7f3a781d | 711 | #ifdef CONFIG_PRINTK |
b4caecd4 | 712 | [11] = { "kmsg", 0644, &kmsg_fops, 0 }, |
7f3a781d | 713 | #endif |
d6f47bef ASF |
714 | }; |
715 | ||
716 | static int memory_open(struct inode *inode, struct file *filp) | |
717 | { | |
389e0cb9 KS |
718 | int minor; |
719 | const struct memdev *dev; | |
d6f47bef | 720 | |
389e0cb9 KS |
721 | minor = iminor(inode); |
722 | if (minor >= ARRAY_SIZE(devlist)) | |
205153aa | 723 | return -ENXIO; |
d6f47bef | 724 | |
389e0cb9 KS |
725 | dev = &devlist[minor]; |
726 | if (!dev->fops) | |
205153aa | 727 | return -ENXIO; |
d6f47bef | 728 | |
389e0cb9 | 729 | filp->f_op = dev->fops; |
b4caecd4 | 730 | filp->f_mode |= dev->fmode; |
4a3956c7 | 731 | |
389e0cb9 | 732 | if (dev->fops->open) |
205153aa FW |
733 | return dev->fops->open(inode, filp); |
734 | ||
735 | return 0; | |
1da177e4 LT |
736 | } |
737 | ||
62322d25 | 738 | static const struct file_operations memory_fops = { |
d7d4d849 | 739 | .open = memory_open, |
6038f373 | 740 | .llseek = noop_llseek, |
1da177e4 LT |
741 | }; |
742 | ||
2c9ede55 | 743 | static char *mem_devnode(struct device *dev, umode_t *mode) |
e454cea2 KS |
744 | { |
745 | if (mode && devlist[MINOR(dev->devt)].mode) | |
746 | *mode = devlist[MINOR(dev->devt)].mode; | |
747 | return NULL; | |
748 | } | |
749 | ||
ca8eca68 | 750 | static struct class *mem_class; |
1da177e4 LT |
751 | |
752 | static int __init chr_dev_init(void) | |
753 | { | |
389e0cb9 | 754 | int minor; |
1da177e4 | 755 | |
d7d4d849 | 756 | if (register_chrdev(MEM_MAJOR, "mem", &memory_fops)) |
1da177e4 LT |
757 | printk("unable to get major %d for memory devs\n", MEM_MAJOR); |
758 | ||
ca8eca68 | 759 | mem_class = class_create(THIS_MODULE, "mem"); |
6e191f7b AB |
760 | if (IS_ERR(mem_class)) |
761 | return PTR_ERR(mem_class); | |
762 | ||
e454cea2 | 763 | mem_class->devnode = mem_devnode; |
389e0cb9 KS |
764 | for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { |
765 | if (!devlist[minor].name) | |
766 | continue; | |
e1612de9 HM |
767 | |
768 | /* | |
890537b3 | 769 | * Create /dev/port? |
e1612de9 HM |
770 | */ |
771 | if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) | |
772 | continue; | |
773 | ||
389e0cb9 KS |
774 | device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), |
775 | NULL, devlist[minor].name); | |
776 | } | |
ebf644c4 | 777 | |
31d1d48e | 778 | return tty_init(); |
1da177e4 LT |
779 | } |
780 | ||
781 | fs_initcall(chr_dev_init); |