Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl
[linux-2.6.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 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
30 #include <asm/uaccess.h>
31 #include <asm/io.h>
32
33 #ifdef CONFIG_IA64
34 # include <linux/efi.h>
35 #endif
36
37 static 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
48 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
49 {
50         if (addr + count > __pa(high_memory))
51                 return 0;
52
53         return 1;
54 }
55
56 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
57 {
58         return 1;
59 }
60 #endif
61
62 #ifdef CONFIG_STRICT_DEVMEM
63 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
64 {
65         u64 from = ((u64)pfn) << PAGE_SHIFT;
66         u64 to = from + size;
67         u64 cursor = from;
68
69         while (cursor < to) {
70                 if (!devmem_is_allowed(pfn)) {
71                         printk(KERN_INFO
72                 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
73                                 current->comm, from, to);
74                         return 0;
75                 }
76                 cursor += PAGE_SIZE;
77                 pfn++;
78         }
79         return 1;
80 }
81 #else
82 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
83 {
84         return 1;
85 }
86 #endif
87
88 void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
89 {
90 }
91
92 /*
93  * This funcion reads the *physical* memory. The f_pos points directly to the
94  * memory location.
95  */
96 static ssize_t read_mem(struct file *file, char __user *buf,
97                         size_t count, loff_t *ppos)
98 {
99         unsigned long p = *ppos;
100         ssize_t read, sz;
101         char *ptr;
102
103         if (!valid_phys_addr_range(p, count))
104                 return -EFAULT;
105         read = 0;
106 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
107         /* we don't have page 0 mapped on sparc and m68k.. */
108         if (p < PAGE_SIZE) {
109                 sz = size_inside_page(p, count);
110                 if (sz > 0) {
111                         if (clear_user(buf, sz))
112                                 return -EFAULT;
113                         buf += sz;
114                         p += sz;
115                         count -= sz;
116                         read += sz;
117                 }
118         }
119 #endif
120
121         while (count > 0) {
122                 unsigned long remaining;
123
124                 sz = size_inside_page(p, count);
125
126                 if (!range_is_allowed(p >> PAGE_SHIFT, count))
127                         return -EPERM;
128
129                 /*
130                  * On ia64 if a page has been mapped somewhere as uncached, then
131                  * it must also be accessed uncached by the kernel or data
132                  * corruption may occur.
133                  */
134                 ptr = xlate_dev_mem_ptr(p);
135                 if (!ptr)
136                         return -EFAULT;
137
138                 remaining = copy_to_user(buf, ptr, sz);
139                 unxlate_dev_mem_ptr(p, ptr);
140                 if (remaining)
141                         return -EFAULT;
142
143                 buf += sz;
144                 p += sz;
145                 count -= sz;
146                 read += sz;
147         }
148
149         *ppos += read;
150         return read;
151 }
152
153 static ssize_t write_mem(struct file *file, const char __user *buf,
154                          size_t count, loff_t *ppos)
155 {
156         unsigned long p = *ppos;
157         ssize_t written, sz;
158         unsigned long copied;
159         void *ptr;
160
161         if (!valid_phys_addr_range(p, count))
162                 return -EFAULT;
163
164         written = 0;
165
166 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
167         /* we don't have page 0 mapped on sparc and m68k.. */
168         if (p < PAGE_SIZE) {
169                 sz = size_inside_page(p, count);
170                 /* Hmm. Do something? */
171                 buf += sz;
172                 p += sz;
173                 count -= sz;
174                 written += sz;
175         }
176 #endif
177
178         while (count > 0) {
179                 sz = size_inside_page(p, count);
180
181                 if (!range_is_allowed(p >> PAGE_SHIFT, sz))
182                         return -EPERM;
183
184                 /*
185                  * On ia64 if a page has been mapped somewhere as uncached, then
186                  * it must also be accessed uncached by the kernel or data
187                  * corruption may occur.
188                  */
189                 ptr = xlate_dev_mem_ptr(p);
190                 if (!ptr) {
191                         if (written)
192                                 break;
193                         return -EFAULT;
194                 }
195
196                 copied = copy_from_user(ptr, buf, sz);
197                 unxlate_dev_mem_ptr(p, ptr);
198                 if (copied) {
199                         written += sz - copied;
200                         if (written)
201                                 break;
202                         return -EFAULT;
203                 }
204
205                 buf += sz;
206                 p += sz;
207                 count -= sz;
208                 written += sz;
209         }
210
211         *ppos += written;
212         return written;
213 }
214
215 int __weak phys_mem_access_prot_allowed(struct file *file,
216         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
217 {
218         return 1;
219 }
220
221 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
222
223 /*
224  * Architectures vary in how they handle caching for addresses
225  * outside of main memory.
226  *
227  */
228 #ifdef pgprot_noncached
229 static int uncached_access(struct file *file, unsigned long addr)
230 {
231 #if defined(CONFIG_IA64)
232         /*
233          * On ia64, we ignore O_DSYNC because we cannot tolerate memory
234          * attribute aliases.
235          */
236         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
237 #elif defined(CONFIG_MIPS)
238         {
239                 extern int __uncached_access(struct file *file,
240                                              unsigned long addr);
241
242                 return __uncached_access(file, addr);
243         }
244 #else
245         /*
246          * Accessing memory above the top the kernel knows about or through a
247          * file pointer
248          * that was marked O_DSYNC will be done non-cached.
249          */
250         if (file->f_flags & O_DSYNC)
251                 return 1;
252         return addr >= __pa(high_memory);
253 #endif
254 }
255 #endif
256
257 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
258                                      unsigned long size, pgprot_t vma_prot)
259 {
260 #ifdef pgprot_noncached
261         unsigned long offset = pfn << PAGE_SHIFT;
262
263         if (uncached_access(file, offset))
264                 return pgprot_noncached(vma_prot);
265 #endif
266         return vma_prot;
267 }
268 #endif
269
270 #ifndef CONFIG_MMU
271 static unsigned long get_unmapped_area_mem(struct file *file,
272                                            unsigned long addr,
273                                            unsigned long len,
274                                            unsigned long pgoff,
275                                            unsigned long flags)
276 {
277         if (!valid_mmap_phys_addr_range(pgoff, len))
278                 return (unsigned long) -EINVAL;
279         return pgoff << PAGE_SHIFT;
280 }
281
282 /* can't do an in-place private mapping if there's no MMU */
283 static inline int private_mapping_ok(struct vm_area_struct *vma)
284 {
285         return vma->vm_flags & VM_MAYSHARE;
286 }
287 #else
288 #define get_unmapped_area_mem   NULL
289
290 static inline int private_mapping_ok(struct vm_area_struct *vma)
291 {
292         return 1;
293 }
294 #endif
295
296 static const struct vm_operations_struct mmap_mem_ops = {
297 #ifdef CONFIG_HAVE_IOREMAP_PROT
298         .access = generic_access_phys
299 #endif
300 };
301
302 static int mmap_mem(struct file *file, struct vm_area_struct *vma)
303 {
304         size_t size = vma->vm_end - vma->vm_start;
305
306         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
307                 return -EINVAL;
308
309         if (!private_mapping_ok(vma))
310                 return -ENOSYS;
311
312         if (!range_is_allowed(vma->vm_pgoff, size))
313                 return -EPERM;
314
315         if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
316                                                 &vma->vm_page_prot))
317                 return -EINVAL;
318
319         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
320                                                  size,
321                                                  vma->vm_page_prot);
322
323         vma->vm_ops = &mmap_mem_ops;
324
325         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
326         if (remap_pfn_range(vma,
327                             vma->vm_start,
328                             vma->vm_pgoff,
329                             size,
330                             vma->vm_page_prot)) {
331                 return -EAGAIN;
332         }
333         return 0;
334 }
335
336 #ifdef CONFIG_DEVKMEM
337 static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
338 {
339         unsigned long pfn;
340
341         /* Turn a kernel-virtual address into a physical page frame */
342         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
343
344         /*
345          * RED-PEN: on some architectures there is more mapped memory than
346          * available in mem_map which pfn_valid checks for. Perhaps should add a
347          * new macro here.
348          *
349          * RED-PEN: vmalloc is not supported right now.
350          */
351         if (!pfn_valid(pfn))
352                 return -EIO;
353
354         vma->vm_pgoff = pfn;
355         return mmap_mem(file, vma);
356 }
357 #endif
358
359 #ifdef CONFIG_CRASH_DUMP
360 /*
361  * Read memory corresponding to the old kernel.
362  */
363 static ssize_t read_oldmem(struct file *file, char __user *buf,
364                                 size_t count, loff_t *ppos)
365 {
366         unsigned long pfn, offset;
367         size_t read = 0, csize;
368         int rc = 0;
369
370         while (count) {
371                 pfn = *ppos / PAGE_SIZE;
372                 if (pfn > saved_max_pfn)
373                         return read;
374
375                 offset = (unsigned long)(*ppos % PAGE_SIZE);
376                 if (count > PAGE_SIZE - offset)
377                         csize = PAGE_SIZE - offset;
378                 else
379                         csize = count;
380
381                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
382                 if (rc < 0)
383                         return rc;
384                 buf += csize;
385                 *ppos += csize;
386                 read += csize;
387                 count -= csize;
388         }
389         return read;
390 }
391 #endif
392
393 #ifdef CONFIG_DEVKMEM
394 /*
395  * This function reads the *virtual* memory as seen by the kernel.
396  */
397 static ssize_t read_kmem(struct file *file, char __user *buf,
398                          size_t count, loff_t *ppos)
399 {
400         unsigned long p = *ppos;
401         ssize_t low_count, read, sz;
402         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
403         int err = 0;
404
405         read = 0;
406         if (p < (unsigned long) high_memory) {
407                 low_count = count;
408                 if (count > (unsigned long)high_memory - p)
409                         low_count = (unsigned long)high_memory - p;
410
411 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
412                 /* we don't have page 0 mapped on sparc and m68k.. */
413                 if (p < PAGE_SIZE && low_count > 0) {
414                         sz = size_inside_page(p, low_count);
415                         if (clear_user(buf, sz))
416                                 return -EFAULT;
417                         buf += sz;
418                         p += sz;
419                         read += sz;
420                         low_count -= sz;
421                         count -= sz;
422                 }
423 #endif
424                 while (low_count > 0) {
425                         sz = size_inside_page(p, low_count);
426
427                         /*
428                          * On ia64 if a page has been mapped somewhere as
429                          * uncached, then it must also be accessed uncached
430                          * by the kernel or data corruption may occur
431                          */
432                         kbuf = xlate_dev_kmem_ptr((char *)p);
433
434                         if (copy_to_user(buf, kbuf, sz))
435                                 return -EFAULT;
436                         buf += sz;
437                         p += sz;
438                         read += sz;
439                         low_count -= sz;
440                         count -= sz;
441                 }
442         }
443
444         if (count > 0) {
445                 kbuf = (char *)__get_free_page(GFP_KERNEL);
446                 if (!kbuf)
447                         return -ENOMEM;
448                 while (count > 0) {
449                         sz = size_inside_page(p, count);
450                         if (!is_vmalloc_or_module_addr((void *)p)) {
451                                 err = -ENXIO;
452                                 break;
453                         }
454                         sz = vread(kbuf, (char *)p, sz);
455                         if (!sz)
456                                 break;
457                         if (copy_to_user(buf, kbuf, sz)) {
458                                 err = -EFAULT;
459                                 break;
460                         }
461                         count -= sz;
462                         buf += sz;
463                         read += sz;
464                         p += sz;
465                 }
466                 free_page((unsigned long)kbuf);
467         }
468         *ppos = p;
469         return read ? read : err;
470 }
471
472
473 static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
474                                 size_t count, loff_t *ppos)
475 {
476         ssize_t written, sz;
477         unsigned long copied;
478
479         written = 0;
480 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
481         /* we don't have page 0 mapped on sparc and m68k.. */
482         if (p < PAGE_SIZE) {
483                 sz = size_inside_page(p, count);
484                 /* Hmm. Do something? */
485                 buf += sz;
486                 p += sz;
487                 count -= sz;
488                 written += sz;
489         }
490 #endif
491
492         while (count > 0) {
493                 char *ptr;
494
495                 sz = size_inside_page(p, count);
496
497                 /*
498                  * On ia64 if a page has been mapped somewhere as uncached, then
499                  * it must also be accessed uncached by the kernel or data
500                  * corruption may occur.
501                  */
502                 ptr = xlate_dev_kmem_ptr((char *)p);
503
504                 copied = copy_from_user(ptr, buf, sz);
505                 if (copied) {
506                         written += sz - copied;
507                         if (written)
508                                 break;
509                         return -EFAULT;
510                 }
511                 buf += sz;
512                 p += sz;
513                 count -= sz;
514                 written += sz;
515         }
516
517         *ppos += written;
518         return written;
519 }
520
521 /*
522  * This function writes to the *virtual* memory as seen by the kernel.
523  */
524 static ssize_t write_kmem(struct file *file, const char __user *buf,
525                           size_t count, loff_t *ppos)
526 {
527         unsigned long p = *ppos;
528         ssize_t wrote = 0;
529         ssize_t virtr = 0;
530         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
531         int err = 0;
532
533         if (p < (unsigned long) high_memory) {
534                 unsigned long to_write = min_t(unsigned long, count,
535                                                (unsigned long)high_memory - p);
536                 wrote = do_write_kmem(p, buf, to_write, ppos);
537                 if (wrote != to_write)
538                         return wrote;
539                 p += wrote;
540                 buf += wrote;
541                 count -= wrote;
542         }
543
544         if (count > 0) {
545                 kbuf = (char *)__get_free_page(GFP_KERNEL);
546                 if (!kbuf)
547                         return wrote ? wrote : -ENOMEM;
548                 while (count > 0) {
549                         unsigned long sz = size_inside_page(p, count);
550                         unsigned long n;
551
552                         if (!is_vmalloc_or_module_addr((void *)p)) {
553                                 err = -ENXIO;
554                                 break;
555                         }
556                         n = copy_from_user(kbuf, buf, sz);
557                         if (n) {
558                                 err = -EFAULT;
559                                 break;
560                         }
561                         vwrite(kbuf, (char *)p, sz);
562                         count -= sz;
563                         buf += sz;
564                         virtr += sz;
565                         p += sz;
566                 }
567                 free_page((unsigned long)kbuf);
568         }
569
570         *ppos = p;
571         return virtr + wrote ? : err;
572 }
573 #endif
574
575 #ifdef CONFIG_DEVPORT
576 static ssize_t read_port(struct file *file, char __user *buf,
577                          size_t count, loff_t *ppos)
578 {
579         unsigned long i = *ppos;
580         char __user *tmp = buf;
581
582         if (!access_ok(VERIFY_WRITE, buf, count))
583                 return -EFAULT;
584         while (count-- > 0 && i < 65536) {
585                 if (__put_user(inb(i), tmp) < 0)
586                         return -EFAULT;
587                 i++;
588                 tmp++;
589         }
590         *ppos = i;
591         return tmp-buf;
592 }
593
594 static ssize_t write_port(struct file *file, const char __user *buf,
595                           size_t count, loff_t *ppos)
596 {
597         unsigned long i = *ppos;
598         const char __user * tmp = buf;
599
600         if (!access_ok(VERIFY_READ, buf, count))
601                 return -EFAULT;
602         while (count-- > 0 && i < 65536) {
603                 char c;
604                 if (__get_user(c, tmp)) {
605                         if (tmp > buf)
606                                 break;
607                         return -EFAULT;
608                 }
609                 outb(c, i);
610                 i++;
611                 tmp++;
612         }
613         *ppos = i;
614         return tmp-buf;
615 }
616 #endif
617
618 static ssize_t read_null(struct file *file, char __user *buf,
619                          size_t count, loff_t *ppos)
620 {
621         return 0;
622 }
623
624 static ssize_t write_null(struct file *file, const char __user *buf,
625                           size_t count, loff_t *ppos)
626 {
627         return count;
628 }
629
630 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
631                         struct splice_desc *sd)
632 {
633         return sd->len;
634 }
635
636 static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
637                                  loff_t *ppos, size_t len, unsigned int flags)
638 {
639         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
640 }
641
642 static ssize_t read_zero(struct file *file, char __user *buf,
643                          size_t count, loff_t *ppos)
644 {
645         size_t written;
646
647         if (!count)
648                 return 0;
649
650         if (!access_ok(VERIFY_WRITE, buf, count))
651                 return -EFAULT;
652
653         written = 0;
654         while (count) {
655                 unsigned long unwritten;
656                 size_t chunk = count;
657
658                 if (chunk > PAGE_SIZE)
659                         chunk = PAGE_SIZE;      /* Just for latency reasons */
660                 unwritten = __clear_user(buf, chunk);
661                 written += chunk - unwritten;
662                 if (unwritten)
663                         break;
664                 if (signal_pending(current))
665                         return written ? written : -ERESTARTSYS;
666                 buf += chunk;
667                 count -= chunk;
668                 cond_resched();
669         }
670         return written ? written : -EFAULT;
671 }
672
673 static int mmap_zero(struct file *file, struct vm_area_struct *vma)
674 {
675 #ifndef CONFIG_MMU
676         return -ENOSYS;
677 #endif
678         if (vma->vm_flags & VM_SHARED)
679                 return shmem_zero_setup(vma);
680         return 0;
681 }
682
683 static ssize_t write_full(struct file *file, const char __user *buf,
684                           size_t count, loff_t *ppos)
685 {
686         return -ENOSPC;
687 }
688
689 /*
690  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
691  * can fopen() both devices with "a" now.  This was previously impossible.
692  * -- SRB.
693  */
694 static loff_t null_lseek(struct file *file, loff_t offset, int orig)
695 {
696         return file->f_pos = 0;
697 }
698
699 /*
700  * The memory devices use the full 32/64 bits of the offset, and so we cannot
701  * check against negative addresses: they are ok. The return value is weird,
702  * though, in that case (0).
703  *
704  * also note that seeking relative to the "end of file" isn't supported:
705  * it has no meaning, so it returns -EINVAL.
706  */
707 static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
708 {
709         loff_t ret;
710
711         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
712         switch (orig) {
713         case SEEK_CUR:
714                 offset += file->f_pos;
715         case SEEK_SET:
716                 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
717                 if ((unsigned long long)offset >= ~0xFFFULL) {
718                         ret = -EOVERFLOW;
719                         break;
720                 }
721                 file->f_pos = offset;
722                 ret = file->f_pos;
723                 force_successful_syscall_return();
724                 break;
725         default:
726                 ret = -EINVAL;
727         }
728         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
729         return ret;
730 }
731
732 static int open_port(struct inode * inode, struct file * filp)
733 {
734         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
735 }
736
737 #define zero_lseek      null_lseek
738 #define full_lseek      null_lseek
739 #define write_zero      write_null
740 #define read_full       read_zero
741 #define open_mem        open_port
742 #define open_kmem       open_mem
743 #define open_oldmem     open_mem
744
745 static const struct file_operations mem_fops = {
746         .llseek         = memory_lseek,
747         .read           = read_mem,
748         .write          = write_mem,
749         .mmap           = mmap_mem,
750         .open           = open_mem,
751         .get_unmapped_area = get_unmapped_area_mem,
752 };
753
754 #ifdef CONFIG_DEVKMEM
755 static const struct file_operations kmem_fops = {
756         .llseek         = memory_lseek,
757         .read           = read_kmem,
758         .write          = write_kmem,
759         .mmap           = mmap_kmem,
760         .open           = open_kmem,
761         .get_unmapped_area = get_unmapped_area_mem,
762 };
763 #endif
764
765 static const struct file_operations null_fops = {
766         .llseek         = null_lseek,
767         .read           = read_null,
768         .write          = write_null,
769         .splice_write   = splice_write_null,
770 };
771
772 #ifdef CONFIG_DEVPORT
773 static const struct file_operations port_fops = {
774         .llseek         = memory_lseek,
775         .read           = read_port,
776         .write          = write_port,
777         .open           = open_port,
778 };
779 #endif
780
781 static const struct file_operations zero_fops = {
782         .llseek         = zero_lseek,
783         .read           = read_zero,
784         .write          = write_zero,
785         .mmap           = mmap_zero,
786 };
787
788 /*
789  * capabilities for /dev/zero
790  * - permits private mappings, "copies" are taken of the source of zeros
791  * - no writeback happens
792  */
793 static struct backing_dev_info zero_bdi = {
794         .name           = "char/mem",
795         .capabilities   = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,
796 };
797
798 static const struct file_operations full_fops = {
799         .llseek         = full_lseek,
800         .read           = read_full,
801         .write          = write_full,
802 };
803
804 #ifdef CONFIG_CRASH_DUMP
805 static const struct file_operations oldmem_fops = {
806         .read   = read_oldmem,
807         .open   = open_oldmem,
808         .llseek = default_llseek,
809 };
810 #endif
811
812 static ssize_t kmsg_write(struct file *file, const char __user *buf,
813                           size_t count, loff_t *ppos)
814 {
815         char *tmp;
816         ssize_t ret;
817
818         tmp = kmalloc(count + 1, GFP_KERNEL);
819         if (tmp == NULL)
820                 return -ENOMEM;
821         ret = -EFAULT;
822         if (!copy_from_user(tmp, buf, count)) {
823                 tmp[count] = 0;
824                 ret = printk("%s", tmp);
825                 if (ret > count)
826                         /* printk can add a prefix */
827                         ret = count;
828         }
829         kfree(tmp);
830         return ret;
831 }
832
833 static const struct file_operations kmsg_fops = {
834         .write = kmsg_write,
835         .llseek = noop_llseek,
836 };
837
838 static const struct memdev {
839         const char *name;
840         mode_t mode;
841         const struct file_operations *fops;
842         struct backing_dev_info *dev_info;
843 } devlist[] = {
844          [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
845 #ifdef CONFIG_DEVKMEM
846          [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
847 #endif
848          [3] = { "null", 0666, &null_fops, NULL },
849 #ifdef CONFIG_DEVPORT
850          [4] = { "port", 0, &port_fops, NULL },
851 #endif
852          [5] = { "zero", 0666, &zero_fops, &zero_bdi },
853          [7] = { "full", 0666, &full_fops, NULL },
854          [8] = { "random", 0666, &random_fops, NULL },
855          [9] = { "urandom", 0666, &urandom_fops, NULL },
856         [11] = { "kmsg", 0, &kmsg_fops, NULL },
857 #ifdef CONFIG_CRASH_DUMP
858         [12] = { "oldmem", 0, &oldmem_fops, NULL },
859 #endif
860 };
861
862 static int memory_open(struct inode *inode, struct file *filp)
863 {
864         int minor;
865         const struct memdev *dev;
866
867         minor = iminor(inode);
868         if (minor >= ARRAY_SIZE(devlist))
869                 return -ENXIO;
870
871         dev = &devlist[minor];
872         if (!dev->fops)
873                 return -ENXIO;
874
875         filp->f_op = dev->fops;
876         if (dev->dev_info)
877                 filp->f_mapping->backing_dev_info = dev->dev_info;
878
879         if (dev->fops->open)
880                 return dev->fops->open(inode, filp);
881
882         return 0;
883 }
884
885 static const struct file_operations memory_fops = {
886         .open = memory_open,
887         .llseek = noop_llseek,
888 };
889
890 static char *mem_devnode(struct device *dev, mode_t *mode)
891 {
892         if (mode && devlist[MINOR(dev->devt)].mode)
893                 *mode = devlist[MINOR(dev->devt)].mode;
894         return NULL;
895 }
896
897 static struct class *mem_class;
898
899 static int __init chr_dev_init(void)
900 {
901         int minor;
902         int err;
903
904         err = bdi_init(&zero_bdi);
905         if (err)
906                 return err;
907
908         if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
909                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
910
911         mem_class = class_create(THIS_MODULE, "mem");
912         if (IS_ERR(mem_class))
913                 return PTR_ERR(mem_class);
914
915         mem_class->devnode = mem_devnode;
916         for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
917                 if (!devlist[minor].name)
918                         continue;
919                 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
920                               NULL, devlist[minor].name);
921         }
922
923         return tty_init();
924 }
925
926 fs_initcall(chr_dev_init);