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