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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
386static ssize_t read_port(struct file *file, char __user *buf,
387 size_t count, loff_t *ppos)
388{
389 unsigned long i = *ppos;
390 char __user *tmp = buf;
391
392 if (!access_ok(buf, count))
393 return -EFAULT;
394 while (count-- > 0 && i < 65536) {
395 if (__put_user(inb(i), tmp) < 0)
396 return -EFAULT;
397 i++;
398 tmp++;
399 }
400 *ppos = i;
401 return tmp-buf;
402}
403
404static ssize_t write_port(struct file *file, const char __user *buf,
405 size_t count, loff_t *ppos)
406{
407 unsigned long i = *ppos;
408 const char __user *tmp = buf;
409
410 if (!access_ok(buf, count))
411 return -EFAULT;
412 while (count-- > 0 && i < 65536) {
413 char c;
414
415 if (__get_user(c, tmp)) {
416 if (tmp > buf)
417 break;
418 return -EFAULT;
419 }
420 outb(c, i);
421 i++;
422 tmp++;
423 }
424 *ppos = i;
425 return tmp-buf;
426}
427
428static ssize_t read_null(struct file *file, char __user *buf,
429 size_t count, loff_t *ppos)
430{
431 return 0;
432}
433
434static ssize_t write_null(struct file *file, const char __user *buf,
435 size_t count, loff_t *ppos)
436{
437 return count;
438}
439
440static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
441{
442 return 0;
443}
444
445static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
446{
447 size_t count = iov_iter_count(from);
448 iov_iter_advance(from, count);
449 return count;
450}
451
452static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
453 struct splice_desc *sd)
454{
455 return sd->len;
456}
457
458static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
459 loff_t *ppos, size_t len, unsigned int flags)
460{
461 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
462}
463
464static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
465{
466 return 0;
467}
468
469static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
470{
471 size_t written = 0;
472
473 while (iov_iter_count(iter)) {
474 size_t chunk = iov_iter_count(iter), n;
475
476 if (chunk > PAGE_SIZE)
477 chunk = PAGE_SIZE; /* Just for latency reasons */
478 n = iov_iter_zero(chunk, iter);
479 if (!n && iov_iter_count(iter))
480 return written ? written : -EFAULT;
481 written += n;
482 if (signal_pending(current))
483 return written ? written : -ERESTARTSYS;
484 if (!need_resched())
485 continue;
486 if (iocb->ki_flags & IOCB_NOWAIT)
487 return written ? written : -EAGAIN;
488 cond_resched();
489 }
490 return written;
491}
492
493static ssize_t read_zero(struct file *file, char __user *buf,
494 size_t count, loff_t *ppos)
495{
496 size_t cleared = 0;
497
498 while (count) {
499 size_t chunk = min_t(size_t, count, PAGE_SIZE);
500 size_t left;
501
502 left = clear_user(buf + cleared, chunk);
503 if (unlikely(left)) {
504 cleared += (chunk - left);
505 if (!cleared)
506 return -EFAULT;
507 break;
508 }
509 cleared += chunk;
510 count -= chunk;
511
512 if (signal_pending(current))
513 break;
514 cond_resched();
515 }
516
517 return cleared;
518}
519
520static int mmap_zero(struct file *file, struct vm_area_struct *vma)
521{
522#ifndef CONFIG_MMU
523 return -ENOSYS;
524#endif
525 if (vma->vm_flags & VM_SHARED)
526 return shmem_zero_setup(vma);
527 vma_set_anonymous(vma);
528 return 0;
529}
530
531static unsigned long get_unmapped_area_zero(struct file *file,
532 unsigned long addr, unsigned long len,
533 unsigned long pgoff, unsigned long flags)
534{
535#ifdef CONFIG_MMU
536 if (flags & MAP_SHARED) {
537 /*
538 * mmap_zero() will call shmem_zero_setup() to create a file,
539 * so use shmem's get_unmapped_area in case it can be huge;
540 * and pass NULL for file as in mmap.c's get_unmapped_area(),
541 * so as not to confuse shmem with our handle on "/dev/zero".
542 */
543 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
544 }
545
546 /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
547 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
548#else
549 return -ENOSYS;
550#endif
551}
552
553static ssize_t write_full(struct file *file, const char __user *buf,
554 size_t count, loff_t *ppos)
555{
556 return -ENOSPC;
557}
558
559/*
560 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
561 * can fopen() both devices with "a" now. This was previously impossible.
562 * -- SRB.
563 */
564static loff_t null_lseek(struct file *file, loff_t offset, int orig)
565{
566 return file->f_pos = 0;
567}
568
569/*
570 * The memory devices use the full 32/64 bits of the offset, and so we cannot
571 * check against negative addresses: they are ok. The return value is weird,
572 * though, in that case (0).
573 *
574 * also note that seeking relative to the "end of file" isn't supported:
575 * it has no meaning, so it returns -EINVAL.
576 */
577static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
578{
579 loff_t ret;
580
581 inode_lock(file_inode(file));
582 switch (orig) {
583 case SEEK_CUR:
584 offset += file->f_pos;
585 fallthrough;
586 case SEEK_SET:
587 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
588 if ((unsigned long long)offset >= -MAX_ERRNO) {
589 ret = -EOVERFLOW;
590 break;
591 }
592 file->f_pos = offset;
593 ret = file->f_pos;
594 force_successful_syscall_return();
595 break;
596 default:
597 ret = -EINVAL;
598 }
599 inode_unlock(file_inode(file));
600 return ret;
601}
602
603static int open_port(struct inode *inode, struct file *filp)
604{
605 int rc;
606
607 if (!capable(CAP_SYS_RAWIO))
608 return -EPERM;
609
610 rc = security_locked_down(LOCKDOWN_DEV_MEM);
611 if (rc)
612 return rc;
613
614 if (iminor(inode) != DEVMEM_MINOR)
615 return 0;
616
617 /*
618 * Use a unified address space to have a single point to manage
619 * revocations when drivers want to take over a /dev/mem mapped
620 * range.
621 */
622 filp->f_mapping = iomem_get_mapping();
623
624 return 0;
625}
626
627#define zero_lseek null_lseek
628#define full_lseek null_lseek
629#define write_zero write_null
630#define write_iter_zero write_iter_null
631#define splice_write_zero splice_write_null
632#define open_mem open_port
633
634static const struct file_operations __maybe_unused mem_fops = {
635 .llseek = memory_lseek,
636 .read = read_mem,
637 .write = write_mem,
638 .mmap = mmap_mem,
639 .open = open_mem,
640#ifndef CONFIG_MMU
641 .get_unmapped_area = get_unmapped_area_mem,
642 .mmap_capabilities = memory_mmap_capabilities,
643#endif
644};
645
646static const struct file_operations null_fops = {
647 .llseek = null_lseek,
648 .read = read_null,
649 .write = write_null,
650 .read_iter = read_iter_null,
651 .write_iter = write_iter_null,
652 .splice_write = splice_write_null,
653 .uring_cmd = uring_cmd_null,
654};
655
656static const struct file_operations __maybe_unused port_fops = {
657 .llseek = memory_lseek,
658 .read = read_port,
659 .write = write_port,
660 .open = open_port,
661};
662
663static const struct file_operations zero_fops = {
664 .llseek = zero_lseek,
665 .write = write_zero,
666 .read_iter = read_iter_zero,
667 .read = read_zero,
668 .write_iter = write_iter_zero,
669 .splice_read = copy_splice_read,
670 .splice_write = splice_write_zero,
671 .mmap = mmap_zero,
672 .get_unmapped_area = get_unmapped_area_zero,
673#ifndef CONFIG_MMU
674 .mmap_capabilities = zero_mmap_capabilities,
675#endif
676};
677
678static const struct file_operations full_fops = {
679 .llseek = full_lseek,
680 .read_iter = read_iter_zero,
681 .write = write_full,
682 .splice_read = copy_splice_read,
683};
684
685static const struct memdev {
686 const char *name;
687 const struct file_operations *fops;
688 fmode_t fmode;
689 umode_t mode;
690} devlist[] = {
691#ifdef CONFIG_DEVMEM
692 [DEVMEM_MINOR] = { "mem", &mem_fops, FMODE_UNSIGNED_OFFSET, 0 },
693#endif
694 [3] = { "null", &null_fops, FMODE_NOWAIT, 0666 },
695#ifdef CONFIG_DEVPORT
696 [4] = { "port", &port_fops, 0, 0 },
697#endif
698 [5] = { "zero", &zero_fops, FMODE_NOWAIT, 0666 },
699 [7] = { "full", &full_fops, 0, 0666 },
700 [8] = { "random", &random_fops, FMODE_NOWAIT, 0666 },
701 [9] = { "urandom", &urandom_fops, FMODE_NOWAIT, 0666 },
702#ifdef CONFIG_PRINTK
703 [11] = { "kmsg", &kmsg_fops, 0, 0644 },
704#endif
705};
706
707static int memory_open(struct inode *inode, struct file *filp)
708{
709 int minor;
710 const struct memdev *dev;
711
712 minor = iminor(inode);
713 if (minor >= ARRAY_SIZE(devlist))
714 return -ENXIO;
715
716 dev = &devlist[minor];
717 if (!dev->fops)
718 return -ENXIO;
719
720 filp->f_op = dev->fops;
721 filp->f_mode |= dev->fmode;
722
723 if (dev->fops->open)
724 return dev->fops->open(inode, filp);
725
726 return 0;
727}
728
729static const struct file_operations memory_fops = {
730 .open = memory_open,
731 .llseek = noop_llseek,
732};
733
734static char *mem_devnode(const struct device *dev, umode_t *mode)
735{
736 if (mode && devlist[MINOR(dev->devt)].mode)
737 *mode = devlist[MINOR(dev->devt)].mode;
738 return NULL;
739}
740
741static const struct class mem_class = {
742 .name = "mem",
743 .devnode = mem_devnode,
744};
745
746static int __init chr_dev_init(void)
747{
748 int retval;
749 int minor;
750
751 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
752 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
753
754 retval = class_register(&mem_class);
755 if (retval)
756 return retval;
757
758 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
759 if (!devlist[minor].name)
760 continue;
761
762 /*
763 * Create /dev/port?
764 */
765 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
766 continue;
767
768 device_create(&mem_class, NULL, MKDEV(MEM_MAJOR, minor),
769 NULL, devlist[minor].name);
770 }
771
772 return tty_init();
773}
774
775fs_initcall(chr_dev_init);
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/raw.h>
20#include <linux/tty.h>
21#include <linux/capability.h>
22#include <linux/ptrace.h>
23#include <linux/device.h>
24#include <linux/highmem.h>
25#include <linux/backing-dev.h>
26#include <linux/shmem_fs.h>
27#include <linux/splice.h>
28#include <linux/pfn.h>
29#include <linux/export.h>
30#include <linux/io.h>
31#include <linux/uio.h>
32
33#include <linux/uaccess.h>
34
35#ifdef CONFIG_IA64
36# include <linux/efi.h>
37#endif
38
39#define DEVPORT_MINOR 4
40
41static inline unsigned long size_inside_page(unsigned long start,
42 unsigned long size)
43{
44 unsigned long sz;
45
46 sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
47
48 return min(sz, size);
49}
50
51#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
52static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
53{
54 return addr + count <= __pa(high_memory);
55}
56
57static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
58{
59 return 1;
60}
61#endif
62
63#ifdef CONFIG_STRICT_DEVMEM
64static inline int page_is_allowed(unsigned long pfn)
65{
66 return devmem_is_allowed(pfn);
67}
68static inline int range_is_allowed(unsigned long pfn, unsigned long size)
69{
70 u64 from = ((u64)pfn) << PAGE_SHIFT;
71 u64 to = from + size;
72 u64 cursor = from;
73
74 while (cursor < to) {
75 if (!devmem_is_allowed(pfn))
76 return 0;
77 cursor += PAGE_SIZE;
78 pfn++;
79 }
80 return 1;
81}
82#else
83static inline int page_is_allowed(unsigned long pfn)
84{
85 return 1;
86}
87static inline int range_is_allowed(unsigned long pfn, unsigned long size)
88{
89 return 1;
90}
91#endif
92
93#ifndef unxlate_dev_mem_ptr
94#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
95void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
96{
97}
98#endif
99
100/*
101 * This funcion reads the *physical* memory. The f_pos points directly to the
102 * memory location.
103 */
104static ssize_t read_mem(struct file *file, char __user *buf,
105 size_t count, loff_t *ppos)
106{
107 phys_addr_t p = *ppos;
108 ssize_t read, sz;
109 void *ptr;
110 char *bounce;
111 int err;
112
113 if (p != *ppos)
114 return 0;
115
116 if (!valid_phys_addr_range(p, count))
117 return -EFAULT;
118 read = 0;
119#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
120 /* we don't have page 0 mapped on sparc and m68k.. */
121 if (p < PAGE_SIZE) {
122 sz = size_inside_page(p, count);
123 if (sz > 0) {
124 if (clear_user(buf, sz))
125 return -EFAULT;
126 buf += sz;
127 p += sz;
128 count -= sz;
129 read += sz;
130 }
131 }
132#endif
133
134 bounce = kmalloc(PAGE_SIZE, GFP_KERNEL);
135 if (!bounce)
136 return -ENOMEM;
137
138 while (count > 0) {
139 unsigned long remaining;
140 int allowed, probe;
141
142 sz = size_inside_page(p, count);
143
144 err = -EPERM;
145 allowed = page_is_allowed(p >> PAGE_SHIFT);
146 if (!allowed)
147 goto failed;
148
149 err = -EFAULT;
150 if (allowed == 2) {
151 /* Show zeros for restricted memory. */
152 remaining = clear_user(buf, sz);
153 } else {
154 /*
155 * On ia64 if a page has been mapped somewhere as
156 * uncached, then it must also be accessed uncached
157 * by the kernel or data corruption may occur.
158 */
159 ptr = xlate_dev_mem_ptr(p);
160 if (!ptr)
161 goto failed;
162
163 probe = probe_kernel_read(bounce, ptr, sz);
164 unxlate_dev_mem_ptr(p, ptr);
165 if (probe)
166 goto failed;
167
168 remaining = copy_to_user(buf, bounce, sz);
169 }
170
171 if (remaining)
172 goto failed;
173
174 buf += sz;
175 p += sz;
176 count -= sz;
177 read += sz;
178 }
179 kfree(bounce);
180
181 *ppos += read;
182 return read;
183
184failed:
185 kfree(bounce);
186 return err;
187}
188
189static ssize_t write_mem(struct file *file, const char __user *buf,
190 size_t count, loff_t *ppos)
191{
192 phys_addr_t p = *ppos;
193 ssize_t written, sz;
194 unsigned long copied;
195 void *ptr;
196
197 if (p != *ppos)
198 return -EFBIG;
199
200 if (!valid_phys_addr_range(p, count))
201 return -EFAULT;
202
203 written = 0;
204
205#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
206 /* we don't have page 0 mapped on sparc and m68k.. */
207 if (p < PAGE_SIZE) {
208 sz = size_inside_page(p, count);
209 /* Hmm. Do something? */
210 buf += sz;
211 p += sz;
212 count -= sz;
213 written += sz;
214 }
215#endif
216
217 while (count > 0) {
218 int allowed;
219
220 sz = size_inside_page(p, count);
221
222 allowed = page_is_allowed(p >> PAGE_SHIFT);
223 if (!allowed)
224 return -EPERM;
225
226 /* Skip actual writing when a page is marked as restricted. */
227 if (allowed == 1) {
228 /*
229 * On ia64 if a page has been mapped somewhere as
230 * uncached, then it must also be accessed uncached
231 * by the kernel or data corruption may occur.
232 */
233 ptr = xlate_dev_mem_ptr(p);
234 if (!ptr) {
235 if (written)
236 break;
237 return -EFAULT;
238 }
239
240 copied = copy_from_user(ptr, buf, sz);
241 unxlate_dev_mem_ptr(p, ptr);
242 if (copied) {
243 written += sz - copied;
244 if (written)
245 break;
246 return -EFAULT;
247 }
248 }
249
250 buf += sz;
251 p += sz;
252 count -= sz;
253 written += sz;
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#if defined(CONFIG_IA64)
277 /*
278 * On ia64, we ignore O_DSYNC because we cannot tolerate memory
279 * attribute aliases.
280 */
281 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
282#elif defined(CONFIG_MIPS)
283 {
284 extern int __uncached_access(struct file *file,
285 unsigned long addr);
286
287 return __uncached_access(file, addr);
288 }
289#else
290 /*
291 * Accessing memory above the top the kernel knows about or through a
292 * file pointer
293 * that was marked O_DSYNC will be done non-cached.
294 */
295 if (file->f_flags & O_DSYNC)
296 return 1;
297 return addr >= __pa(high_memory);
298#endif
299}
300#endif
301
302static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
303 unsigned long size, pgprot_t vma_prot)
304{
305#ifdef pgprot_noncached
306 phys_addr_t offset = pfn << PAGE_SHIFT;
307
308 if (uncached_access(file, offset))
309 return pgprot_noncached(vma_prot);
310#endif
311 return vma_prot;
312}
313#endif
314
315#ifndef CONFIG_MMU
316static unsigned long get_unmapped_area_mem(struct file *file,
317 unsigned long addr,
318 unsigned long len,
319 unsigned long pgoff,
320 unsigned long flags)
321{
322 if (!valid_mmap_phys_addr_range(pgoff, len))
323 return (unsigned long) -EINVAL;
324 return pgoff << PAGE_SHIFT;
325}
326
327/* permit direct mmap, for read, write or exec */
328static unsigned memory_mmap_capabilities(struct file *file)
329{
330 return NOMMU_MAP_DIRECT |
331 NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;
332}
333
334static unsigned zero_mmap_capabilities(struct file *file)
335{
336 return NOMMU_MAP_COPY;
337}
338
339/* can't do an in-place private mapping if there's no MMU */
340static inline int private_mapping_ok(struct vm_area_struct *vma)
341{
342 return vma->vm_flags & VM_MAYSHARE;
343}
344#else
345
346static inline int private_mapping_ok(struct vm_area_struct *vma)
347{
348 return 1;
349}
350#endif
351
352static const struct vm_operations_struct mmap_mem_ops = {
353#ifdef CONFIG_HAVE_IOREMAP_PROT
354 .access = generic_access_phys
355#endif
356};
357
358static int mmap_mem(struct file *file, struct vm_area_struct *vma)
359{
360 size_t size = vma->vm_end - vma->vm_start;
361 phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
362
363 /* Does it even fit in phys_addr_t? */
364 if (offset >> PAGE_SHIFT != vma->vm_pgoff)
365 return -EINVAL;
366
367 /* It's illegal to wrap around the end of the physical address space. */
368 if (offset + (phys_addr_t)size - 1 < offset)
369 return -EINVAL;
370
371 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
372 return -EINVAL;
373
374 if (!private_mapping_ok(vma))
375 return -ENOSYS;
376
377 if (!range_is_allowed(vma->vm_pgoff, size))
378 return -EPERM;
379
380 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
381 &vma->vm_page_prot))
382 return -EINVAL;
383
384 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
385 size,
386 vma->vm_page_prot);
387
388 vma->vm_ops = &mmap_mem_ops;
389
390 /* Remap-pfn-range will mark the range VM_IO */
391 if (remap_pfn_range(vma,
392 vma->vm_start,
393 vma->vm_pgoff,
394 size,
395 vma->vm_page_prot)) {
396 return -EAGAIN;
397 }
398 return 0;
399}
400
401static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
402{
403 unsigned long pfn;
404
405 /* Turn a kernel-virtual address into a physical page frame */
406 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
407
408 /*
409 * RED-PEN: on some architectures there is more mapped memory than
410 * available in mem_map which pfn_valid checks for. Perhaps should add a
411 * new macro here.
412 *
413 * RED-PEN: vmalloc is not supported right now.
414 */
415 if (!pfn_valid(pfn))
416 return -EIO;
417
418 vma->vm_pgoff = pfn;
419 return mmap_mem(file, vma);
420}
421
422/*
423 * This function reads the *virtual* memory as seen by the kernel.
424 */
425static ssize_t read_kmem(struct file *file, char __user *buf,
426 size_t count, loff_t *ppos)
427{
428 unsigned long p = *ppos;
429 ssize_t low_count, read, sz;
430 char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
431 int err = 0;
432
433 read = 0;
434 if (p < (unsigned long) high_memory) {
435 low_count = count;
436 if (count > (unsigned long)high_memory - p)
437 low_count = (unsigned long)high_memory - p;
438
439#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
440 /* we don't have page 0 mapped on sparc and m68k.. */
441 if (p < PAGE_SIZE && low_count > 0) {
442 sz = size_inside_page(p, low_count);
443 if (clear_user(buf, sz))
444 return -EFAULT;
445 buf += sz;
446 p += sz;
447 read += sz;
448 low_count -= sz;
449 count -= sz;
450 }
451#endif
452 while (low_count > 0) {
453 sz = size_inside_page(p, low_count);
454
455 /*
456 * On ia64 if a page has been mapped somewhere as
457 * uncached, then it must also be accessed uncached
458 * by the kernel or data corruption may occur
459 */
460 kbuf = xlate_dev_kmem_ptr((void *)p);
461 if (!virt_addr_valid(kbuf))
462 return -ENXIO;
463
464 if (copy_to_user(buf, kbuf, sz))
465 return -EFAULT;
466 buf += sz;
467 p += sz;
468 read += sz;
469 low_count -= sz;
470 count -= sz;
471 }
472 }
473
474 if (count > 0) {
475 kbuf = (char *)__get_free_page(GFP_KERNEL);
476 if (!kbuf)
477 return -ENOMEM;
478 while (count > 0) {
479 sz = size_inside_page(p, count);
480 if (!is_vmalloc_or_module_addr((void *)p)) {
481 err = -ENXIO;
482 break;
483 }
484 sz = vread(kbuf, (char *)p, sz);
485 if (!sz)
486 break;
487 if (copy_to_user(buf, kbuf, sz)) {
488 err = -EFAULT;
489 break;
490 }
491 count -= sz;
492 buf += sz;
493 read += sz;
494 p += sz;
495 }
496 free_page((unsigned long)kbuf);
497 }
498 *ppos = p;
499 return read ? read : err;
500}
501
502
503static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
504 size_t count, loff_t *ppos)
505{
506 ssize_t written, sz;
507 unsigned long copied;
508
509 written = 0;
510#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
511 /* we don't have page 0 mapped on sparc and m68k.. */
512 if (p < PAGE_SIZE) {
513 sz = size_inside_page(p, count);
514 /* Hmm. Do something? */
515 buf += sz;
516 p += sz;
517 count -= sz;
518 written += sz;
519 }
520#endif
521
522 while (count > 0) {
523 void *ptr;
524
525 sz = size_inside_page(p, count);
526
527 /*
528 * On ia64 if a page has been mapped somewhere as uncached, then
529 * it must also be accessed uncached by the kernel or data
530 * corruption may occur.
531 */
532 ptr = xlate_dev_kmem_ptr((void *)p);
533 if (!virt_addr_valid(ptr))
534 return -ENXIO;
535
536 copied = copy_from_user(ptr, buf, sz);
537 if (copied) {
538 written += sz - copied;
539 if (written)
540 break;
541 return -EFAULT;
542 }
543 buf += sz;
544 p += sz;
545 count -= sz;
546 written += sz;
547 }
548
549 *ppos += written;
550 return written;
551}
552
553/*
554 * This function writes to the *virtual* memory as seen by the kernel.
555 */
556static ssize_t write_kmem(struct file *file, const char __user *buf,
557 size_t count, loff_t *ppos)
558{
559 unsigned long p = *ppos;
560 ssize_t wrote = 0;
561 ssize_t virtr = 0;
562 char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
563 int err = 0;
564
565 if (p < (unsigned long) high_memory) {
566 unsigned long to_write = min_t(unsigned long, count,
567 (unsigned long)high_memory - p);
568 wrote = do_write_kmem(p, buf, to_write, ppos);
569 if (wrote != to_write)
570 return wrote;
571 p += wrote;
572 buf += wrote;
573 count -= wrote;
574 }
575
576 if (count > 0) {
577 kbuf = (char *)__get_free_page(GFP_KERNEL);
578 if (!kbuf)
579 return wrote ? wrote : -ENOMEM;
580 while (count > 0) {
581 unsigned long sz = size_inside_page(p, count);
582 unsigned long n;
583
584 if (!is_vmalloc_or_module_addr((void *)p)) {
585 err = -ENXIO;
586 break;
587 }
588 n = copy_from_user(kbuf, buf, sz);
589 if (n) {
590 err = -EFAULT;
591 break;
592 }
593 vwrite(kbuf, (char *)p, sz);
594 count -= sz;
595 buf += sz;
596 virtr += sz;
597 p += sz;
598 }
599 free_page((unsigned long)kbuf);
600 }
601
602 *ppos = p;
603 return virtr + wrote ? : err;
604}
605
606static ssize_t read_port(struct file *file, char __user *buf,
607 size_t count, loff_t *ppos)
608{
609 unsigned long i = *ppos;
610 char __user *tmp = buf;
611
612 if (!access_ok(VERIFY_WRITE, buf, count))
613 return -EFAULT;
614 while (count-- > 0 && i < 65536) {
615 if (__put_user(inb(i), tmp) < 0)
616 return -EFAULT;
617 i++;
618 tmp++;
619 }
620 *ppos = i;
621 return tmp-buf;
622}
623
624static ssize_t write_port(struct file *file, const char __user *buf,
625 size_t count, loff_t *ppos)
626{
627 unsigned long i = *ppos;
628 const char __user *tmp = buf;
629
630 if (!access_ok(VERIFY_READ, buf, count))
631 return -EFAULT;
632 while (count-- > 0 && i < 65536) {
633 char c;
634
635 if (__get_user(c, tmp)) {
636 if (tmp > buf)
637 break;
638 return -EFAULT;
639 }
640 outb(c, i);
641 i++;
642 tmp++;
643 }
644 *ppos = i;
645 return tmp-buf;
646}
647
648static ssize_t read_null(struct file *file, char __user *buf,
649 size_t count, loff_t *ppos)
650{
651 return 0;
652}
653
654static ssize_t write_null(struct file *file, const char __user *buf,
655 size_t count, loff_t *ppos)
656{
657 return count;
658}
659
660static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
661{
662 return 0;
663}
664
665static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
666{
667 size_t count = iov_iter_count(from);
668 iov_iter_advance(from, count);
669 return count;
670}
671
672static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
673 struct splice_desc *sd)
674{
675 return sd->len;
676}
677
678static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
679 loff_t *ppos, size_t len, unsigned int flags)
680{
681 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
682}
683
684static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
685{
686 size_t written = 0;
687
688 while (iov_iter_count(iter)) {
689 size_t chunk = iov_iter_count(iter), n;
690
691 if (chunk > PAGE_SIZE)
692 chunk = PAGE_SIZE; /* Just for latency reasons */
693 n = iov_iter_zero(chunk, iter);
694 if (!n && iov_iter_count(iter))
695 return written ? written : -EFAULT;
696 written += n;
697 if (signal_pending(current))
698 return written ? written : -ERESTARTSYS;
699 cond_resched();
700 }
701 return written;
702}
703
704static int mmap_zero(struct file *file, struct vm_area_struct *vma)
705{
706#ifndef CONFIG_MMU
707 return -ENOSYS;
708#endif
709 if (vma->vm_flags & VM_SHARED)
710 return shmem_zero_setup(vma);
711 return 0;
712}
713
714static unsigned long get_unmapped_area_zero(struct file *file,
715 unsigned long addr, unsigned long len,
716 unsigned long pgoff, unsigned long flags)
717{
718#ifdef CONFIG_MMU
719 if (flags & MAP_SHARED) {
720 /*
721 * mmap_zero() will call shmem_zero_setup() to create a file,
722 * so use shmem's get_unmapped_area in case it can be huge;
723 * and pass NULL for file as in mmap.c's get_unmapped_area(),
724 * so as not to confuse shmem with our handle on "/dev/zero".
725 */
726 return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags);
727 }
728
729 /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
730 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
731#else
732 return -ENOSYS;
733#endif
734}
735
736static ssize_t write_full(struct file *file, const char __user *buf,
737 size_t count, loff_t *ppos)
738{
739 return -ENOSPC;
740}
741
742/*
743 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
744 * can fopen() both devices with "a" now. This was previously impossible.
745 * -- SRB.
746 */
747static loff_t null_lseek(struct file *file, loff_t offset, int orig)
748{
749 return file->f_pos = 0;
750}
751
752/*
753 * The memory devices use the full 32/64 bits of the offset, and so we cannot
754 * check against negative addresses: they are ok. The return value is weird,
755 * though, in that case (0).
756 *
757 * also note that seeking relative to the "end of file" isn't supported:
758 * it has no meaning, so it returns -EINVAL.
759 */
760static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
761{
762 loff_t ret;
763
764 inode_lock(file_inode(file));
765 switch (orig) {
766 case SEEK_CUR:
767 offset += file->f_pos;
768 case SEEK_SET:
769 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
770 if ((unsigned long long)offset >= -MAX_ERRNO) {
771 ret = -EOVERFLOW;
772 break;
773 }
774 file->f_pos = offset;
775 ret = file->f_pos;
776 force_successful_syscall_return();
777 break;
778 default:
779 ret = -EINVAL;
780 }
781 inode_unlock(file_inode(file));
782 return ret;
783}
784
785static int open_port(struct inode *inode, struct file *filp)
786{
787 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
788}
789
790#define zero_lseek null_lseek
791#define full_lseek null_lseek
792#define write_zero write_null
793#define write_iter_zero write_iter_null
794#define open_mem open_port
795#define open_kmem open_mem
796
797static const struct file_operations __maybe_unused mem_fops = {
798 .llseek = memory_lseek,
799 .read = read_mem,
800 .write = write_mem,
801 .mmap = mmap_mem,
802 .open = open_mem,
803#ifndef CONFIG_MMU
804 .get_unmapped_area = get_unmapped_area_mem,
805 .mmap_capabilities = memory_mmap_capabilities,
806#endif
807};
808
809static const struct file_operations __maybe_unused kmem_fops = {
810 .llseek = memory_lseek,
811 .read = read_kmem,
812 .write = write_kmem,
813 .mmap = mmap_kmem,
814 .open = open_kmem,
815#ifndef CONFIG_MMU
816 .get_unmapped_area = get_unmapped_area_mem,
817 .mmap_capabilities = memory_mmap_capabilities,
818#endif
819};
820
821static const struct file_operations null_fops = {
822 .llseek = null_lseek,
823 .read = read_null,
824 .write = write_null,
825 .read_iter = read_iter_null,
826 .write_iter = write_iter_null,
827 .splice_write = splice_write_null,
828};
829
830static const struct file_operations __maybe_unused port_fops = {
831 .llseek = memory_lseek,
832 .read = read_port,
833 .write = write_port,
834 .open = open_port,
835};
836
837static const struct file_operations zero_fops = {
838 .llseek = zero_lseek,
839 .write = write_zero,
840 .read_iter = read_iter_zero,
841 .write_iter = write_iter_zero,
842 .mmap = mmap_zero,
843 .get_unmapped_area = get_unmapped_area_zero,
844#ifndef CONFIG_MMU
845 .mmap_capabilities = zero_mmap_capabilities,
846#endif
847};
848
849static const struct file_operations full_fops = {
850 .llseek = full_lseek,
851 .read_iter = read_iter_zero,
852 .write = write_full,
853};
854
855static const struct memdev {
856 const char *name;
857 umode_t mode;
858 const struct file_operations *fops;
859 fmode_t fmode;
860} devlist[] = {
861#ifdef CONFIG_DEVMEM
862 [1] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
863#endif
864#ifdef CONFIG_DEVKMEM
865 [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET },
866#endif
867 [3] = { "null", 0666, &null_fops, 0 },
868#ifdef CONFIG_DEVPORT
869 [4] = { "port", 0, &port_fops, 0 },
870#endif
871 [5] = { "zero", 0666, &zero_fops, 0 },
872 [7] = { "full", 0666, &full_fops, 0 },
873 [8] = { "random", 0666, &random_fops, 0 },
874 [9] = { "urandom", 0666, &urandom_fops, 0 },
875#ifdef CONFIG_PRINTK
876 [11] = { "kmsg", 0644, &kmsg_fops, 0 },
877#endif
878};
879
880static int memory_open(struct inode *inode, struct file *filp)
881{
882 int minor;
883 const struct memdev *dev;
884
885 minor = iminor(inode);
886 if (minor >= ARRAY_SIZE(devlist))
887 return -ENXIO;
888
889 dev = &devlist[minor];
890 if (!dev->fops)
891 return -ENXIO;
892
893 filp->f_op = dev->fops;
894 filp->f_mode |= dev->fmode;
895
896 if (dev->fops->open)
897 return dev->fops->open(inode, filp);
898
899 return 0;
900}
901
902static const struct file_operations memory_fops = {
903 .open = memory_open,
904 .llseek = noop_llseek,
905};
906
907static char *mem_devnode(struct device *dev, umode_t *mode)
908{
909 if (mode && devlist[MINOR(dev->devt)].mode)
910 *mode = devlist[MINOR(dev->devt)].mode;
911 return NULL;
912}
913
914static struct class *mem_class;
915
916static int __init chr_dev_init(void)
917{
918 int minor;
919
920 if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
921 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
922
923 mem_class = class_create(THIS_MODULE, "mem");
924 if (IS_ERR(mem_class))
925 return PTR_ERR(mem_class);
926
927 mem_class->devnode = mem_devnode;
928 for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
929 if (!devlist[minor].name)
930 continue;
931
932 /*
933 * Create /dev/port?
934 */
935 if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
936 continue;
937
938 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
939 NULL, devlist[minor].name);
940 }
941
942 return tty_init();
943}
944
945fs_initcall(chr_dev_init);