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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/crash_dump.h>
25#include <linux/backing-dev.h>
26#include <linux/bootmem.h>
27#include <linux/splice.h>
28#include <linux/pfn.h>
29#include <linux/export.h>
30
31#include <asm/uaccess.h>
32#include <asm/io.h>
33
34#ifdef CONFIG_IA64
35# include <linux/efi.h>
36#endif
37
38static inline unsigned long size_inside_page(unsigned long start,
39 unsigned long size)
40{
41 unsigned long sz;
42
43 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
44
45 return min(sz, size);
46}
47
48#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
49static inline int valid_phys_addr_range(unsigned long addr, size_t count)
50{
51 return addr + count <= __pa(high_memory);
52}
53
54static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
55{
56 return 1;
57}
58#endif
59
60#ifdef CONFIG_STRICT_DEVMEM
61static inline int range_is_allowed(unsigned long pfn, unsigned long size)
62{
63 u64 from = ((u64)pfn) << PAGE_SHIFT;
64 u64 to = from + size;
65 u64 cursor = from;
66
67 while (cursor < to) {
68 if (!devmem_is_allowed(pfn)) {
69 printk(KERN_INFO
70 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
71 current->comm, from, to);
72 return 0;
73 }
74 cursor += PAGE_SIZE;
75 pfn++;
76 }
77 return 1;
78}
79#else
80static inline int range_is_allowed(unsigned long pfn, unsigned long size)
81{
82 return 1;
83}
84#endif
85
86void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
87{
88}
89
90/*
91 * This funcion reads the *physical* memory. The f_pos points directly to the
92 * memory location.
93 */
94static ssize_t read_mem(struct file *file, char __user *buf,
95 size_t count, loff_t *ppos)
96{
97 unsigned long p = *ppos;
98 ssize_t read, sz;
99 char *ptr;
100
101 if (!valid_phys_addr_range(p, count))
102 return -EFAULT;
103 read = 0;
104#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
105 /* we don't have page 0 mapped on sparc and m68k.. */
106 if (p < PAGE_SIZE) {
107 sz = size_inside_page(p, count);
108 if (sz > 0) {
109 if (clear_user(buf, sz))
110 return -EFAULT;
111 buf += sz;
112 p += sz;
113 count -= sz;
114 read += sz;
115 }
116 }
117#endif
118
119 while (count > 0) {
120 unsigned long remaining;
121
122 sz = size_inside_page(p, count);
123
124 if (!range_is_allowed(p >> PAGE_SHIFT, count))
125 return -EPERM;
126
127 /*
128 * On ia64 if a page has been mapped somewhere as uncached, then
129 * it must also be accessed uncached by the kernel or data
130 * corruption may occur.
131 */
132 ptr = xlate_dev_mem_ptr(p);
133 if (!ptr)
134 return -EFAULT;
135
136 remaining = copy_to_user(buf, ptr, sz);
137 unxlate_dev_mem_ptr(p, ptr);
138 if (remaining)
139 return -EFAULT;
140
141 buf += sz;
142 p += sz;
143 count -= sz;
144 read += sz;
145 }
146
147 *ppos += read;
148 return read;
149}
150
151static ssize_t write_mem(struct file *file, const char __user *buf,
152 size_t count, loff_t *ppos)
153{
154 unsigned long p = *ppos;
155 ssize_t written, sz;
156 unsigned long copied;
157 void *ptr;
158
159 if (!valid_phys_addr_range(p, count))
160 return -EFAULT;
161
162 written = 0;
163
164#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
165 /* we don't have page 0 mapped on sparc and m68k.. */
166 if (p < PAGE_SIZE) {
167 sz = size_inside_page(p, count);
168 /* Hmm. Do something? */
169 buf += sz;
170 p += sz;
171 count -= sz;
172 written += sz;
173 }
174#endif
175
176 while (count > 0) {
177 sz = size_inside_page(p, count);
178
179 if (!range_is_allowed(p >> PAGE_SHIFT, sz))
180 return -EPERM;
181
182 /*
183 * On ia64 if a page has been mapped somewhere as uncached, then
184 * it must also be accessed uncached by the kernel or data
185 * corruption may occur.
186 */
187 ptr = xlate_dev_mem_ptr(p);
188 if (!ptr) {
189 if (written)
190 break;
191 return -EFAULT;
192 }
193
194 copied = copy_from_user(ptr, buf, sz);
195 unxlate_dev_mem_ptr(p, ptr);
196 if (copied) {
197 written += sz - copied;
198 if (written)
199 break;
200 return -EFAULT;
201 }
202
203 buf += sz;
204 p += sz;
205 count -= sz;
206 written += sz;
207 }
208
209 *ppos += written;
210 return written;
211}
212
213int __weak phys_mem_access_prot_allowed(struct file *file,
214 unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
215{
216 return 1;
217}
218
219#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
220
221/*
222 * Architectures vary in how they handle caching for addresses
223 * outside of main memory.
224 *
225 */
226#ifdef pgprot_noncached
227static int uncached_access(struct file *file, unsigned long addr)
228{
229#if defined(CONFIG_IA64)
230 /*
231 * On ia64, we ignore O_DSYNC because we cannot tolerate memory
232 * attribute aliases.
233 */
234 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
235#elif defined(CONFIG_MIPS)
236 {
237 extern int __uncached_access(struct file *file,
238 unsigned long addr);
239
240 return __uncached_access(file, addr);
241 }
242#else
243 /*
244 * Accessing memory above the top the kernel knows about or through a
245 * file pointer
246 * that was marked O_DSYNC will be done non-cached.
247 */
248 if (file->f_flags & O_DSYNC)
249 return 1;
250 return addr >= __pa(high_memory);
251#endif
252}
253#endif
254
255static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
256 unsigned long size, pgprot_t vma_prot)
257{
258#ifdef pgprot_noncached
259 unsigned long offset = pfn << PAGE_SHIFT;
260
261 if (uncached_access(file, offset))
262 return pgprot_noncached(vma_prot);
263#endif
264 return vma_prot;
265}
266#endif
267
268#ifndef CONFIG_MMU
269static unsigned long get_unmapped_area_mem(struct file *file,
270 unsigned long addr,
271 unsigned long len,
272 unsigned long pgoff,
273 unsigned long flags)
274{
275 if (!valid_mmap_phys_addr_range(pgoff, len))
276 return (unsigned long) -EINVAL;
277 return pgoff << PAGE_SHIFT;
278}
279
280/* can't do an in-place private mapping if there's no MMU */
281static inline int private_mapping_ok(struct vm_area_struct *vma)
282{
283 return vma->vm_flags & VM_MAYSHARE;
284}
285#else
286#define get_unmapped_area_mem NULL
287
288static inline int private_mapping_ok(struct vm_area_struct *vma)
289{
290 return 1;
291}
292#endif
293
294static const struct vm_operations_struct mmap_mem_ops = {
295#ifdef CONFIG_HAVE_IOREMAP_PROT
296 .access = generic_access_phys
297#endif
298};
299
300static int mmap_mem(struct file *file, struct vm_area_struct *vma)
301{
302 size_t size = vma->vm_end - vma->vm_start;
303
304 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
305 return -EINVAL;
306
307 if (!private_mapping_ok(vma))
308 return -ENOSYS;
309
310 if (!range_is_allowed(vma->vm_pgoff, size))
311 return -EPERM;
312
313 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
314 &vma->vm_page_prot))
315 return -EINVAL;
316
317 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
318 size,
319 vma->vm_page_prot);
320
321 vma->vm_ops = &mmap_mem_ops;
322
323 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
324 if (remap_pfn_range(vma,
325 vma->vm_start,
326 vma->vm_pgoff,
327 size,
328 vma->vm_page_prot)) {
329 return -EAGAIN;
330 }
331 return 0;
332}
333
334#ifdef CONFIG_DEVKMEM
335static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
336{
337 unsigned long pfn;
338
339 /* Turn a kernel-virtual address into a physical page frame */
340 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
341
342 /*
343 * RED-PEN: on some architectures there is more mapped memory than
344 * available in mem_map which pfn_valid checks for. Perhaps should add a
345 * new macro here.
346 *
347 * RED-PEN: vmalloc is not supported right now.
348 */
349 if (!pfn_valid(pfn))
350 return -EIO;
351
352 vma->vm_pgoff = pfn;
353 return mmap_mem(file, vma);
354}
355#endif
356
357#ifdef CONFIG_CRASH_DUMP
358/*
359 * Read memory corresponding to the old kernel.
360 */
361static ssize_t read_oldmem(struct file *file, char __user *buf,
362 size_t count, loff_t *ppos)
363{
364 unsigned long pfn, offset;
365 size_t read = 0, csize;
366 int rc = 0;
367
368 while (count) {
369 pfn = *ppos / PAGE_SIZE;
370 if (pfn > saved_max_pfn)
371 return read;
372
373 offset = (unsigned long)(*ppos % PAGE_SIZE);
374 if (count > PAGE_SIZE - offset)
375 csize = PAGE_SIZE - offset;
376 else
377 csize = count;
378
379 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
380 if (rc < 0)
381 return rc;
382 buf += csize;
383 *ppos += csize;
384 read += csize;
385 count -= csize;
386 }
387 return read;
388}
389#endif
390
391#ifdef CONFIG_DEVKMEM
392/*
393 * This function reads the *virtual* memory as seen by the kernel.
394 */
395static ssize_t read_kmem(struct file *file, char __user *buf,
396 size_t count, loff_t *ppos)
397{
398 unsigned long p = *ppos;
399 ssize_t low_count, read, sz;
400 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
401 int err = 0;
402
403 read = 0;
404 if (p < (unsigned long) high_memory) {
405 low_count = count;
406 if (count > (unsigned long)high_memory - p)
407 low_count = (unsigned long)high_memory - p;
408
409#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
410 /* we don't have page 0 mapped on sparc and m68k.. */
411 if (p < PAGE_SIZE && low_count > 0) {
412 sz = size_inside_page(p, low_count);
413 if (clear_user(buf, sz))
414 return -EFAULT;
415 buf += sz;
416 p += sz;
417 read += sz;
418 low_count -= sz;
419 count -= sz;
420 }
421#endif
422 while (low_count > 0) {
423 sz = size_inside_page(p, low_count);
424
425 /*
426 * On ia64 if a page has been mapped somewhere as
427 * uncached, then it must also be accessed uncached
428 * by the kernel or data corruption may occur
429 */
430 kbuf = xlate_dev_kmem_ptr((char *)p);
431
432 if (copy_to_user(buf, kbuf, sz))
433 return -EFAULT;
434 buf += sz;
435 p += sz;
436 read += sz;
437 low_count -= sz;
438 count -= sz;
439 }
440 }
441
442 if (count > 0) {
443 kbuf = (char *)__get_free_page(GFP_KERNEL);
444 if (!kbuf)
445 return -ENOMEM;
446 while (count > 0) {
447 sz = size_inside_page(p, count);
448 if (!is_vmalloc_or_module_addr((void *)p)) {
449 err = -ENXIO;
450 break;
451 }
452 sz = vread(kbuf, (char *)p, sz);
453 if (!sz)
454 break;
455 if (copy_to_user(buf, kbuf, sz)) {
456 err = -EFAULT;
457 break;
458 }
459 count -= sz;
460 buf += sz;
461 read += sz;
462 p += sz;
463 }
464 free_page((unsigned long)kbuf);
465 }
466 *ppos = p;
467 return read ? read : err;
468}
469
470
471static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
472 size_t count, loff_t *ppos)
473{
474 ssize_t written, sz;
475 unsigned long copied;
476
477 written = 0;
478#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
479 /* we don't have page 0 mapped on sparc and m68k.. */
480 if (p < PAGE_SIZE) {
481 sz = size_inside_page(p, count);
482 /* Hmm. Do something? */
483 buf += sz;
484 p += sz;
485 count -= sz;
486 written += sz;
487 }
488#endif
489
490 while (count > 0) {
491 char *ptr;
492
493 sz = size_inside_page(p, count);
494
495 /*
496 * On ia64 if a page has been mapped somewhere as uncached, then
497 * it must also be accessed uncached by the kernel or data
498 * corruption may occur.
499 */
500 ptr = xlate_dev_kmem_ptr((char *)p);
501
502 copied = copy_from_user(ptr, buf, sz);
503 if (copied) {
504 written += sz - copied;
505 if (written)
506 break;
507 return -EFAULT;
508 }
509 buf += sz;
510 p += sz;
511 count -= sz;
512 written += sz;
513 }
514
515 *ppos += written;
516 return written;
517}
518
519/*
520 * This function writes to the *virtual* memory as seen by the kernel.
521 */
522static ssize_t write_kmem(struct file *file, const char __user *buf,
523 size_t count, loff_t *ppos)
524{
525 unsigned long p = *ppos;
526 ssize_t wrote = 0;
527 ssize_t virtr = 0;
528 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
529 int err = 0;
530
531 if (p < (unsigned long) high_memory) {
532 unsigned long to_write = min_t(unsigned long, count,
533 (unsigned long)high_memory - p);
534 wrote = do_write_kmem(p, buf, to_write, ppos);
535 if (wrote != to_write)
536 return wrote;
537 p += wrote;
538 buf += wrote;
539 count -= wrote;
540 }
541
542 if (count > 0) {
543 kbuf = (char *)__get_free_page(GFP_KERNEL);
544 if (!kbuf)
545 return wrote ? wrote : -ENOMEM;
546 while (count > 0) {
547 unsigned long sz = size_inside_page(p, count);
548 unsigned long n;
549
550 if (!is_vmalloc_or_module_addr((void *)p)) {
551 err = -ENXIO;
552 break;
553 }
554 n = copy_from_user(kbuf, buf, sz);
555 if (n) {
556 err = -EFAULT;
557 break;
558 }
559 vwrite(kbuf, (char *)p, sz);
560 count -= sz;
561 buf += sz;
562 virtr += sz;
563 p += sz;
564 }
565 free_page((unsigned long)kbuf);
566 }
567
568 *ppos = p;
569 return virtr + wrote ? : err;
570}
571#endif
572
573#ifdef CONFIG_DEVPORT
574static ssize_t read_port(struct file *file, char __user *buf,
575 size_t count, loff_t *ppos)
576{
577 unsigned long i = *ppos;
578 char __user *tmp = buf;
579
580 if (!access_ok(VERIFY_WRITE, buf, count))
581 return -EFAULT;
582 while (count-- > 0 && i < 65536) {
583 if (__put_user(inb(i), tmp) < 0)
584 return -EFAULT;
585 i++;
586 tmp++;
587 }
588 *ppos = i;
589 return tmp-buf;
590}
591
592static ssize_t write_port(struct file *file, const char __user *buf,
593 size_t count, loff_t *ppos)
594{
595 unsigned long i = *ppos;
596 const char __user * tmp = buf;
597
598 if (!access_ok(VERIFY_READ, buf, count))
599 return -EFAULT;
600 while (count-- > 0 && i < 65536) {
601 char c;
602 if (__get_user(c, tmp)) {
603 if (tmp > buf)
604 break;
605 return -EFAULT;
606 }
607 outb(c, i);
608 i++;
609 tmp++;
610 }
611 *ppos = i;
612 return tmp-buf;
613}
614#endif
615
616static ssize_t read_null(struct file *file, char __user *buf,
617 size_t count, loff_t *ppos)
618{
619 return 0;
620}
621
622static ssize_t write_null(struct file *file, const char __user *buf,
623 size_t count, loff_t *ppos)
624{
625 return count;
626}
627
628static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
629 struct splice_desc *sd)
630{
631 return sd->len;
632}
633
634static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
635 loff_t *ppos, size_t len, unsigned int flags)
636{
637 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
638}
639
640static ssize_t read_zero(struct file *file, char __user *buf,
641 size_t count, loff_t *ppos)
642{
643 size_t written;
644
645 if (!count)
646 return 0;
647
648 if (!access_ok(VERIFY_WRITE, buf, count))
649 return -EFAULT;
650
651 written = 0;
652 while (count) {
653 unsigned long unwritten;
654 size_t chunk = count;
655
656 if (chunk > PAGE_SIZE)
657 chunk = PAGE_SIZE; /* Just for latency reasons */
658 unwritten = __clear_user(buf, chunk);
659 written += chunk - unwritten;
660 if (unwritten)
661 break;
662 if (signal_pending(current))
663 return written ? written : -ERESTARTSYS;
664 buf += chunk;
665 count -= chunk;
666 cond_resched();
667 }
668 return written ? written : -EFAULT;
669}
670
671static int mmap_zero(struct file *file, struct vm_area_struct *vma)
672{
673#ifndef CONFIG_MMU
674 return -ENOSYS;
675#endif
676 if (vma->vm_flags & VM_SHARED)
677 return shmem_zero_setup(vma);
678 return 0;
679}
680
681static ssize_t write_full(struct file *file, const char __user *buf,
682 size_t count, loff_t *ppos)
683{
684 return -ENOSPC;
685}
686
687/*
688 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
689 * can fopen() both devices with "a" now. This was previously impossible.
690 * -- SRB.
691 */
692static loff_t null_lseek(struct file *file, loff_t offset, int orig)
693{
694 return file->f_pos = 0;
695}
696
697/*
698 * The memory devices use the full 32/64 bits of the offset, and so we cannot
699 * check against negative addresses: they are ok. The return value is weird,
700 * though, in that case (0).
701 *
702 * also note that seeking relative to the "end of file" isn't supported:
703 * it has no meaning, so it returns -EINVAL.
704 */
705static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
706{
707 loff_t ret;
708
709 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
710 switch (orig) {
711 case SEEK_CUR:
712 offset += file->f_pos;
713 case SEEK_SET:
714 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
715 if ((unsigned long long)offset >= ~0xFFFULL) {
716 ret = -EOVERFLOW;
717 break;
718 }
719 file->f_pos = offset;
720 ret = file->f_pos;
721 force_successful_syscall_return();
722 break;
723 default:
724 ret = -EINVAL;
725 }
726 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
727 return ret;
728}
729
730static int open_port(struct inode * inode, struct file * filp)
731{
732 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
733}
734
735#define zero_lseek null_lseek
736#define full_lseek null_lseek
737#define write_zero write_null
738#define read_full read_zero
739#define open_mem open_port
740#define open_kmem open_mem
741#define open_oldmem open_mem
742
743static const struct file_operations mem_fops = {
744 .llseek = memory_lseek,
745 .read = read_mem,
746 .write = write_mem,
747 .mmap = mmap_mem,
748 .open = open_mem,
749 .get_unmapped_area = get_unmapped_area_mem,
750};
751
752#ifdef CONFIG_DEVKMEM
753static const struct file_operations kmem_fops = {
754 .llseek = memory_lseek,
755 .read = read_kmem,
756 .write = write_kmem,
757 .mmap = mmap_kmem,
758 .open = open_kmem,
759 .get_unmapped_area = get_unmapped_area_mem,
760};
761#endif
762
763static const struct file_operations null_fops = {
764 .llseek = null_lseek,
765 .read = read_null,
766 .write = write_null,
767 .splice_write = splice_write_null,
768};
769
770#ifdef CONFIG_DEVPORT
771static const struct file_operations port_fops = {
772 .llseek = memory_lseek,
773 .read = read_port,
774 .write = write_port,
775 .open = open_port,
776};
777#endif
778
779static const struct file_operations zero_fops = {
780 .llseek = zero_lseek,
781 .read = read_zero,
782 .write = write_zero,
783 .mmap = mmap_zero,
784};
785
786/*
787 * capabilities for /dev/zero
788 * - permits private mappings, "copies" are taken of the source of zeros
789 * - no writeback happens
790 */
791static struct backing_dev_info zero_bdi = {
792 .name = "char/mem",
793 .capabilities = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,
794};
795
796static const struct file_operations full_fops = {
797 .llseek = full_lseek,
798 .read = read_full,
799 .write = write_full,
800};
801
802#ifdef CONFIG_CRASH_DUMP
803static const struct file_operations oldmem_fops = {
804 .read = read_oldmem,
805 .open = open_oldmem,
806 .llseek = default_llseek,
807};
808#endif
809
810static const struct memdev {
811 const char *name;
812 umode_t mode;
813 const struct file_operations *fops;
814 struct backing_dev_info *dev_info;
815} devlist[] = {
816 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
817#ifdef CONFIG_DEVKMEM
818 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
819#endif
820 [3] = { "null", 0666, &null_fops, NULL },
821#ifdef CONFIG_DEVPORT
822 [4] = { "port", 0, &port_fops, NULL },
823#endif
824 [5] = { "zero", 0666, &zero_fops, &zero_bdi },
825 [7] = { "full", 0666, &full_fops, NULL },
826 [8] = { "random", 0666, &random_fops, NULL },
827 [9] = { "urandom", 0666, &urandom_fops, NULL },
828#ifdef CONFIG_PRINTK
829 [11] = { "kmsg", 0644, &kmsg_fops, NULL },
830#endif
831#ifdef CONFIG_CRASH_DUMP
832 [12] = { "oldmem", 0, &oldmem_fops, NULL },
833#endif
834};
835
836static int memory_open(struct inode *inode, struct file *filp)
837{
838 int minor;
839 const struct memdev *dev;
840
841 minor = iminor(inode);
842 if (minor >= ARRAY_SIZE(devlist))
843 return -ENXIO;
844
845 dev = &devlist[minor];
846 if (!dev->fops)
847 return -ENXIO;
848
849 filp->f_op = dev->fops;
850 if (dev->dev_info)
851 filp->f_mapping->backing_dev_info = dev->dev_info;
852
853 /* Is /dev/mem or /dev/kmem ? */
854 if (dev->dev_info == &directly_mappable_cdev_bdi)
855 filp->f_mode |= FMODE_UNSIGNED_OFFSET;
856
857 if (dev->fops->open)
858 return dev->fops->open(inode, filp);
859
860 return 0;
861}
862
863static const struct file_operations memory_fops = {
864 .open = memory_open,
865 .llseek = noop_llseek,
866};
867
868static char *mem_devnode(struct device *dev, umode_t *mode)
869{
870 if (mode && devlist[MINOR(dev->devt)].mode)
871 *mode = devlist[MINOR(dev->devt)].mode;
872 return NULL;
873}
874
875static struct class *mem_class;
876
877static int __init chr_dev_init(void)
878{
879 int minor;
880 int err;
881
882 err = bdi_init(&zero_bdi);
883 if (err)
884 return err;
885
886 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
887 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
888
889 mem_class = class_create(THIS_MODULE, "mem");
890 if (IS_ERR(mem_class))
891 return PTR_ERR(mem_class);
892
893 mem_class->devnode = mem_devnode;
894 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
895 if (!devlist[minor].name)
896 continue;
897 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
898 NULL, devlist[minor].name);
899 }
900
901 return tty_init();
902}
903
904fs_initcall(chr_dev_init);