]> git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - drivers/char/mem.c
Merge branch 'upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/linville...
[mirror_ubuntu-jammy-kernel.git] / drivers / char / mem.c
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 mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
9 */
10
11 #include <linux/config.h>
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/smp_lock.h>
23 #include <linux/devfs_fs_kernel.h>
24 #include <linux/ptrace.h>
25 #include <linux/device.h>
26 #include <linux/highmem.h>
27 #include <linux/crash_dump.h>
28 #include <linux/backing-dev.h>
29 #include <linux/bootmem.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
38 /*
39 * Architectures vary in how they handle caching for addresses
40 * outside of main memory.
41 *
42 */
43 static inline int uncached_access(struct file *file, unsigned long addr)
44 {
45 #if defined(__i386__)
46 /*
47 * On the PPro and successors, the MTRRs are used to set
48 * memory types for physical addresses outside main memory,
49 * so blindly setting PCD or PWT on those pages is wrong.
50 * For Pentiums and earlier, the surround logic should disable
51 * caching for the high addresses through the KEN pin, but
52 * we maintain the tradition of paranoia in this code.
53 */
54 if (file->f_flags & O_SYNC)
55 return 1;
56 return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
57 test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
58 test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
59 test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
60 && addr >= __pa(high_memory);
61 #elif defined(__x86_64__)
62 /*
63 * This is broken because it can generate memory type aliases,
64 * which can cause cache corruptions
65 * But it is only available for root and we have to be bug-to-bug
66 * compatible with i386.
67 */
68 if (file->f_flags & O_SYNC)
69 return 1;
70 /* same behaviour as i386. PAT always set to cached and MTRRs control the
71 caching behaviour.
72 Hopefully a full PAT implementation will fix that soon. */
73 return 0;
74 #elif defined(CONFIG_IA64)
75 /*
76 * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
77 */
78 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
79 #else
80 /*
81 * Accessing memory above the top the kernel knows about or through a file pointer
82 * that was marked O_SYNC will be done non-cached.
83 */
84 if (file->f_flags & O_SYNC)
85 return 1;
86 return addr >= __pa(high_memory);
87 #endif
88 }
89
90 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
91 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
92 {
93 if (addr + count > __pa(high_memory))
94 return 0;
95
96 return 1;
97 }
98
99 static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t size)
100 {
101 return 1;
102 }
103 #endif
104
105 /*
106 * This funcion reads the *physical* memory. The f_pos points directly to the
107 * memory location.
108 */
109 static ssize_t read_mem(struct file * file, char __user * buf,
110 size_t count, loff_t *ppos)
111 {
112 unsigned long p = *ppos;
113 ssize_t read, sz;
114 char *ptr;
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 = PAGE_SIZE - p;
123 if (sz > count)
124 sz = count;
125 if (sz > 0) {
126 if (clear_user(buf, sz))
127 return -EFAULT;
128 buf += sz;
129 p += sz;
130 count -= sz;
131 read += sz;
132 }
133 }
134 #endif
135
136 while (count > 0) {
137 /*
138 * Handle first page in case it's not aligned
139 */
140 if (-p & (PAGE_SIZE - 1))
141 sz = -p & (PAGE_SIZE - 1);
142 else
143 sz = PAGE_SIZE;
144
145 sz = min_t(unsigned long, sz, count);
146
147 /*
148 * On ia64 if a page has been mapped somewhere as
149 * uncached, then it must also be accessed uncached
150 * by the kernel or data corruption may occur
151 */
152 ptr = xlate_dev_mem_ptr(p);
153
154 if (copy_to_user(buf, ptr, sz))
155 return -EFAULT;
156 buf += sz;
157 p += sz;
158 count -= sz;
159 read += sz;
160 }
161
162 *ppos += read;
163 return read;
164 }
165
166 static ssize_t write_mem(struct file * file, const char __user * buf,
167 size_t count, loff_t *ppos)
168 {
169 unsigned long p = *ppos;
170 ssize_t written, sz;
171 unsigned long copied;
172 void *ptr;
173
174 if (!valid_phys_addr_range(p, count))
175 return -EFAULT;
176
177 written = 0;
178
179 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
180 /* we don't have page 0 mapped on sparc and m68k.. */
181 if (p < PAGE_SIZE) {
182 unsigned long sz = PAGE_SIZE - p;
183 if (sz > count)
184 sz = count;
185 /* Hmm. Do something? */
186 buf += sz;
187 p += sz;
188 count -= sz;
189 written += sz;
190 }
191 #endif
192
193 while (count > 0) {
194 /*
195 * Handle first page in case it's not aligned
196 */
197 if (-p & (PAGE_SIZE - 1))
198 sz = -p & (PAGE_SIZE - 1);
199 else
200 sz = PAGE_SIZE;
201
202 sz = min_t(unsigned long, sz, count);
203
204 /*
205 * On ia64 if a page has been mapped somewhere as
206 * uncached, then it must also be accessed uncached
207 * by the kernel or data corruption may occur
208 */
209 ptr = xlate_dev_mem_ptr(p);
210
211 copied = copy_from_user(ptr, buf, sz);
212 if (copied) {
213 written += sz - copied;
214 if (written)
215 break;
216 return -EFAULT;
217 }
218 buf += sz;
219 p += sz;
220 count -= sz;
221 written += sz;
222 }
223
224 *ppos += written;
225 return written;
226 }
227
228 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
229 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
230 unsigned long size, pgprot_t vma_prot)
231 {
232 #ifdef pgprot_noncached
233 unsigned long offset = pfn << PAGE_SHIFT;
234
235 if (uncached_access(file, offset))
236 return pgprot_noncached(vma_prot);
237 #endif
238 return vma_prot;
239 }
240 #endif
241
242 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
243 {
244 size_t size = vma->vm_end - vma->vm_start;
245
246 if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, size))
247 return -EINVAL;
248
249 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
250 size,
251 vma->vm_page_prot);
252
253 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
254 if (remap_pfn_range(vma,
255 vma->vm_start,
256 vma->vm_pgoff,
257 size,
258 vma->vm_page_prot))
259 return -EAGAIN;
260 return 0;
261 }
262
263 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
264 {
265 unsigned long pfn;
266
267 /* Turn a kernel-virtual address into a physical page frame */
268 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
269
270 /*
271 * RED-PEN: on some architectures there is more mapped memory
272 * than available in mem_map which pfn_valid checks
273 * for. Perhaps should add a new macro here.
274 *
275 * RED-PEN: vmalloc is not supported right now.
276 */
277 if (!pfn_valid(pfn))
278 return -EIO;
279
280 vma->vm_pgoff = pfn;
281 return mmap_mem(file, vma);
282 }
283
284 #ifdef CONFIG_CRASH_DUMP
285 /*
286 * Read memory corresponding to the old kernel.
287 */
288 static ssize_t read_oldmem(struct file *file, char __user *buf,
289 size_t count, loff_t *ppos)
290 {
291 unsigned long pfn, offset;
292 size_t read = 0, csize;
293 int rc = 0;
294
295 while (count) {
296 pfn = *ppos / PAGE_SIZE;
297 if (pfn > saved_max_pfn)
298 return read;
299
300 offset = (unsigned long)(*ppos % PAGE_SIZE);
301 if (count > PAGE_SIZE - offset)
302 csize = PAGE_SIZE - offset;
303 else
304 csize = count;
305
306 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
307 if (rc < 0)
308 return rc;
309 buf += csize;
310 *ppos += csize;
311 read += csize;
312 count -= csize;
313 }
314 return read;
315 }
316 #endif
317
318 extern long vread(char *buf, char *addr, unsigned long count);
319 extern long vwrite(char *buf, char *addr, unsigned long count);
320
321 /*
322 * This function reads the *virtual* memory as seen by the kernel.
323 */
324 static ssize_t read_kmem(struct file *file, char __user *buf,
325 size_t count, loff_t *ppos)
326 {
327 unsigned long p = *ppos;
328 ssize_t low_count, read, sz;
329 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
330
331 read = 0;
332 if (p < (unsigned long) high_memory) {
333 low_count = count;
334 if (count > (unsigned long) high_memory - p)
335 low_count = (unsigned long) high_memory - p;
336
337 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
338 /* we don't have page 0 mapped on sparc and m68k.. */
339 if (p < PAGE_SIZE && low_count > 0) {
340 size_t tmp = PAGE_SIZE - p;
341 if (tmp > low_count) tmp = low_count;
342 if (clear_user(buf, tmp))
343 return -EFAULT;
344 buf += tmp;
345 p += tmp;
346 read += tmp;
347 low_count -= tmp;
348 count -= tmp;
349 }
350 #endif
351 while (low_count > 0) {
352 /*
353 * Handle first page in case it's not aligned
354 */
355 if (-p & (PAGE_SIZE - 1))
356 sz = -p & (PAGE_SIZE - 1);
357 else
358 sz = PAGE_SIZE;
359
360 sz = min_t(unsigned long, sz, low_count);
361
362 /*
363 * On ia64 if a page has been mapped somewhere as
364 * uncached, then it must also be accessed uncached
365 * by the kernel or data corruption may occur
366 */
367 kbuf = xlate_dev_kmem_ptr((char *)p);
368
369 if (copy_to_user(buf, kbuf, sz))
370 return -EFAULT;
371 buf += sz;
372 p += sz;
373 read += sz;
374 low_count -= sz;
375 count -= sz;
376 }
377 }
378
379 if (count > 0) {
380 kbuf = (char *)__get_free_page(GFP_KERNEL);
381 if (!kbuf)
382 return -ENOMEM;
383 while (count > 0) {
384 int len = count;
385
386 if (len > PAGE_SIZE)
387 len = PAGE_SIZE;
388 len = vread(kbuf, (char *)p, len);
389 if (!len)
390 break;
391 if (copy_to_user(buf, kbuf, len)) {
392 free_page((unsigned long)kbuf);
393 return -EFAULT;
394 }
395 count -= len;
396 buf += len;
397 read += len;
398 p += len;
399 }
400 free_page((unsigned long)kbuf);
401 }
402 *ppos = p;
403 return read;
404 }
405
406
407 static inline ssize_t
408 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
409 size_t count, loff_t *ppos)
410 {
411 ssize_t written, sz;
412 unsigned long copied;
413
414 written = 0;
415 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
416 /* we don't have page 0 mapped on sparc and m68k.. */
417 if (realp < PAGE_SIZE) {
418 unsigned long sz = PAGE_SIZE - realp;
419 if (sz > count)
420 sz = count;
421 /* Hmm. Do something? */
422 buf += sz;
423 p += sz;
424 realp += sz;
425 count -= sz;
426 written += sz;
427 }
428 #endif
429
430 while (count > 0) {
431 char *ptr;
432 /*
433 * Handle first page in case it's not aligned
434 */
435 if (-realp & (PAGE_SIZE - 1))
436 sz = -realp & (PAGE_SIZE - 1);
437 else
438 sz = PAGE_SIZE;
439
440 sz = min_t(unsigned long, sz, count);
441
442 /*
443 * On ia64 if a page has been mapped somewhere as
444 * uncached, then it must also be accessed uncached
445 * by the kernel or data corruption may occur
446 */
447 ptr = xlate_dev_kmem_ptr(p);
448
449 copied = copy_from_user(ptr, buf, sz);
450 if (copied) {
451 written += sz - copied;
452 if (written)
453 break;
454 return -EFAULT;
455 }
456 buf += sz;
457 p += sz;
458 realp += sz;
459 count -= sz;
460 written += sz;
461 }
462
463 *ppos += written;
464 return written;
465 }
466
467
468 /*
469 * This function writes to the *virtual* memory as seen by the kernel.
470 */
471 static ssize_t write_kmem(struct file * file, const char __user * buf,
472 size_t count, loff_t *ppos)
473 {
474 unsigned long p = *ppos;
475 ssize_t wrote = 0;
476 ssize_t virtr = 0;
477 ssize_t written;
478 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
479
480 if (p < (unsigned long) high_memory) {
481
482 wrote = count;
483 if (count > (unsigned long) high_memory - p)
484 wrote = (unsigned long) high_memory - p;
485
486 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
487 if (written != wrote)
488 return written;
489 wrote = written;
490 p += wrote;
491 buf += wrote;
492 count -= wrote;
493 }
494
495 if (count > 0) {
496 kbuf = (char *)__get_free_page(GFP_KERNEL);
497 if (!kbuf)
498 return wrote ? wrote : -ENOMEM;
499 while (count > 0) {
500 int len = count;
501
502 if (len > PAGE_SIZE)
503 len = PAGE_SIZE;
504 if (len) {
505 written = copy_from_user(kbuf, buf, len);
506 if (written) {
507 if (wrote + virtr)
508 break;
509 free_page((unsigned long)kbuf);
510 return -EFAULT;
511 }
512 }
513 len = vwrite(kbuf, (char *)p, len);
514 count -= len;
515 buf += len;
516 virtr += len;
517 p += len;
518 }
519 free_page((unsigned long)kbuf);
520 }
521
522 *ppos = p;
523 return virtr + wrote;
524 }
525
526 #if defined(CONFIG_ISA) || !defined(__mc68000__)
527 static ssize_t read_port(struct file * file, char __user * buf,
528 size_t count, loff_t *ppos)
529 {
530 unsigned long i = *ppos;
531 char __user *tmp = buf;
532
533 if (!access_ok(VERIFY_WRITE, buf, count))
534 return -EFAULT;
535 while (count-- > 0 && i < 65536) {
536 if (__put_user(inb(i),tmp) < 0)
537 return -EFAULT;
538 i++;
539 tmp++;
540 }
541 *ppos = i;
542 return tmp-buf;
543 }
544
545 static ssize_t write_port(struct file * file, const char __user * buf,
546 size_t count, loff_t *ppos)
547 {
548 unsigned long i = *ppos;
549 const char __user * tmp = buf;
550
551 if (!access_ok(VERIFY_READ,buf,count))
552 return -EFAULT;
553 while (count-- > 0 && i < 65536) {
554 char c;
555 if (__get_user(c, tmp)) {
556 if (tmp > buf)
557 break;
558 return -EFAULT;
559 }
560 outb(c,i);
561 i++;
562 tmp++;
563 }
564 *ppos = i;
565 return tmp-buf;
566 }
567 #endif
568
569 static ssize_t read_null(struct file * file, char __user * buf,
570 size_t count, loff_t *ppos)
571 {
572 return 0;
573 }
574
575 static ssize_t write_null(struct file * file, const char __user * buf,
576 size_t count, loff_t *ppos)
577 {
578 return count;
579 }
580
581 #ifdef CONFIG_MMU
582 /*
583 * For fun, we are using the MMU for this.
584 */
585 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
586 {
587 struct mm_struct *mm;
588 struct vm_area_struct * vma;
589 unsigned long addr=(unsigned long)buf;
590
591 mm = current->mm;
592 /* Oops, this was forgotten before. -ben */
593 down_read(&mm->mmap_sem);
594
595 /* For private mappings, just map in zero pages. */
596 for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
597 unsigned long count;
598
599 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
600 goto out_up;
601 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
602 break;
603 count = vma->vm_end - addr;
604 if (count > size)
605 count = size;
606
607 zap_page_range(vma, addr, count, NULL);
608 zeromap_page_range(vma, addr, count, PAGE_COPY);
609
610 size -= count;
611 buf += count;
612 addr += count;
613 if (size == 0)
614 goto out_up;
615 }
616
617 up_read(&mm->mmap_sem);
618
619 /* The shared case is hard. Let's do the conventional zeroing. */
620 do {
621 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
622 if (unwritten)
623 return size + unwritten - PAGE_SIZE;
624 cond_resched();
625 buf += PAGE_SIZE;
626 size -= PAGE_SIZE;
627 } while (size);
628
629 return size;
630 out_up:
631 up_read(&mm->mmap_sem);
632 return size;
633 }
634
635 static ssize_t read_zero(struct file * file, char __user * buf,
636 size_t count, loff_t *ppos)
637 {
638 unsigned long left, unwritten, written = 0;
639
640 if (!count)
641 return 0;
642
643 if (!access_ok(VERIFY_WRITE, buf, count))
644 return -EFAULT;
645
646 left = count;
647
648 /* do we want to be clever? Arbitrary cut-off */
649 if (count >= PAGE_SIZE*4) {
650 unsigned long partial;
651
652 /* How much left of the page? */
653 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
654 unwritten = clear_user(buf, partial);
655 written = partial - unwritten;
656 if (unwritten)
657 goto out;
658 left -= partial;
659 buf += partial;
660 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
661 written += (left & PAGE_MASK) - unwritten;
662 if (unwritten)
663 goto out;
664 buf += left & PAGE_MASK;
665 left &= ~PAGE_MASK;
666 }
667 unwritten = clear_user(buf, left);
668 written += left - unwritten;
669 out:
670 return written ? written : -EFAULT;
671 }
672
673 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
674 {
675 if (vma->vm_flags & VM_SHARED)
676 return shmem_zero_setup(vma);
677 if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
678 return -EAGAIN;
679 return 0;
680 }
681 #else /* CONFIG_MMU */
682 static ssize_t read_zero(struct file * file, char * buf,
683 size_t count, loff_t *ppos)
684 {
685 size_t todo = count;
686
687 while (todo) {
688 size_t chunk = todo;
689
690 if (chunk > 4096)
691 chunk = 4096; /* Just for latency reasons */
692 if (clear_user(buf, chunk))
693 return -EFAULT;
694 buf += chunk;
695 todo -= chunk;
696 cond_resched();
697 }
698 return count;
699 }
700
701 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
702 {
703 return -ENOSYS;
704 }
705 #endif /* CONFIG_MMU */
706
707 static ssize_t write_full(struct file * file, const char __user * buf,
708 size_t count, loff_t *ppos)
709 {
710 return -ENOSPC;
711 }
712
713 /*
714 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
715 * can fopen() both devices with "a" now. This was previously impossible.
716 * -- SRB.
717 */
718
719 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
720 {
721 return file->f_pos = 0;
722 }
723
724 /*
725 * The memory devices use the full 32/64 bits of the offset, and so we cannot
726 * check against negative addresses: they are ok. The return value is weird,
727 * though, in that case (0).
728 *
729 * also note that seeking relative to the "end of file" isn't supported:
730 * it has no meaning, so it returns -EINVAL.
731 */
732 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
733 {
734 loff_t ret;
735
736 mutex_lock(&file->f_dentry->d_inode->i_mutex);
737 switch (orig) {
738 case 0:
739 file->f_pos = offset;
740 ret = file->f_pos;
741 force_successful_syscall_return();
742 break;
743 case 1:
744 file->f_pos += offset;
745 ret = file->f_pos;
746 force_successful_syscall_return();
747 break;
748 default:
749 ret = -EINVAL;
750 }
751 mutex_unlock(&file->f_dentry->d_inode->i_mutex);
752 return ret;
753 }
754
755 static int open_port(struct inode * inode, struct file * filp)
756 {
757 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
758 }
759
760 #define zero_lseek null_lseek
761 #define full_lseek null_lseek
762 #define write_zero write_null
763 #define read_full read_zero
764 #define open_mem open_port
765 #define open_kmem open_mem
766 #define open_oldmem open_mem
767
768 static struct file_operations mem_fops = {
769 .llseek = memory_lseek,
770 .read = read_mem,
771 .write = write_mem,
772 .mmap = mmap_mem,
773 .open = open_mem,
774 };
775
776 static struct file_operations kmem_fops = {
777 .llseek = memory_lseek,
778 .read = read_kmem,
779 .write = write_kmem,
780 .mmap = mmap_kmem,
781 .open = open_kmem,
782 };
783
784 static struct file_operations null_fops = {
785 .llseek = null_lseek,
786 .read = read_null,
787 .write = write_null,
788 };
789
790 #if defined(CONFIG_ISA) || !defined(__mc68000__)
791 static struct file_operations port_fops = {
792 .llseek = memory_lseek,
793 .read = read_port,
794 .write = write_port,
795 .open = open_port,
796 };
797 #endif
798
799 static struct file_operations zero_fops = {
800 .llseek = zero_lseek,
801 .read = read_zero,
802 .write = write_zero,
803 .mmap = mmap_zero,
804 };
805
806 static struct backing_dev_info zero_bdi = {
807 .capabilities = BDI_CAP_MAP_COPY,
808 };
809
810 static struct file_operations full_fops = {
811 .llseek = full_lseek,
812 .read = read_full,
813 .write = write_full,
814 };
815
816 #ifdef CONFIG_CRASH_DUMP
817 static struct file_operations oldmem_fops = {
818 .read = read_oldmem,
819 .open = open_oldmem,
820 };
821 #endif
822
823 static ssize_t kmsg_write(struct file * file, const char __user * buf,
824 size_t count, loff_t *ppos)
825 {
826 char *tmp;
827 ssize_t ret;
828
829 tmp = kmalloc(count + 1, GFP_KERNEL);
830 if (tmp == NULL)
831 return -ENOMEM;
832 ret = -EFAULT;
833 if (!copy_from_user(tmp, buf, count)) {
834 tmp[count] = 0;
835 ret = printk("%s", tmp);
836 if (ret > count)
837 /* printk can add a prefix */
838 ret = count;
839 }
840 kfree(tmp);
841 return ret;
842 }
843
844 static struct file_operations kmsg_fops = {
845 .write = kmsg_write,
846 };
847
848 static int memory_open(struct inode * inode, struct file * filp)
849 {
850 switch (iminor(inode)) {
851 case 1:
852 filp->f_op = &mem_fops;
853 break;
854 case 2:
855 filp->f_op = &kmem_fops;
856 break;
857 case 3:
858 filp->f_op = &null_fops;
859 break;
860 #if defined(CONFIG_ISA) || !defined(__mc68000__)
861 case 4:
862 filp->f_op = &port_fops;
863 break;
864 #endif
865 case 5:
866 filp->f_mapping->backing_dev_info = &zero_bdi;
867 filp->f_op = &zero_fops;
868 break;
869 case 7:
870 filp->f_op = &full_fops;
871 break;
872 case 8:
873 filp->f_op = &random_fops;
874 break;
875 case 9:
876 filp->f_op = &urandom_fops;
877 break;
878 case 11:
879 filp->f_op = &kmsg_fops;
880 break;
881 #ifdef CONFIG_CRASH_DUMP
882 case 12:
883 filp->f_op = &oldmem_fops;
884 break;
885 #endif
886 default:
887 return -ENXIO;
888 }
889 if (filp->f_op && filp->f_op->open)
890 return filp->f_op->open(inode,filp);
891 return 0;
892 }
893
894 static struct file_operations memory_fops = {
895 .open = memory_open, /* just a selector for the real open */
896 };
897
898 static const struct {
899 unsigned int minor;
900 char *name;
901 umode_t mode;
902 const struct file_operations *fops;
903 } devlist[] = { /* list of minor devices */
904 {1, "mem", S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
905 {2, "kmem", S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
906 {3, "null", S_IRUGO | S_IWUGO, &null_fops},
907 #if defined(CONFIG_ISA) || !defined(__mc68000__)
908 {4, "port", S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
909 #endif
910 {5, "zero", S_IRUGO | S_IWUGO, &zero_fops},
911 {7, "full", S_IRUGO | S_IWUGO, &full_fops},
912 {8, "random", S_IRUGO | S_IWUSR, &random_fops},
913 {9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops},
914 {11,"kmsg", S_IRUGO | S_IWUSR, &kmsg_fops},
915 #ifdef CONFIG_CRASH_DUMP
916 {12,"oldmem", S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
917 #endif
918 };
919
920 static struct class *mem_class;
921
922 static int __init chr_dev_init(void)
923 {
924 int i;
925
926 if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
927 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
928
929 mem_class = class_create(THIS_MODULE, "mem");
930 for (i = 0; i < ARRAY_SIZE(devlist); i++) {
931 class_device_create(mem_class, NULL,
932 MKDEV(MEM_MAJOR, devlist[i].minor),
933 NULL, devlist[i].name);
934 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
935 S_IFCHR | devlist[i].mode, devlist[i].name);
936 }
937
938 return 0;
939 }
940
941 fs_initcall(chr_dev_init);