splice: divorce the splice structure/function definitions from the pipe header
[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 mmaping 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 /*
38  * Architectures vary in how they handle caching for addresses
39  * outside of main memory.
40  *
41  */
42 static inline int uncached_access(struct file *file, unsigned long addr)
43 {
44 #if defined(__i386__)
45         /*
46          * On the PPro and successors, the MTRRs are used to set
47          * memory types for physical addresses outside main memory,
48          * so blindly setting PCD or PWT on those pages is wrong.
49          * For Pentiums and earlier, the surround logic should disable
50          * caching for the high addresses through the KEN pin, but
51          * we maintain the tradition of paranoia in this code.
52          */
53         if (file->f_flags & O_SYNC)
54                 return 1;
55         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
56                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
57                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
58                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
59           && addr >= __pa(high_memory);
60 #elif defined(__x86_64__)
61         /* 
62          * This is broken because it can generate memory type aliases,
63          * which can cause cache corruptions
64          * But it is only available for root and we have to be bug-to-bug
65          * compatible with i386.
66          */
67         if (file->f_flags & O_SYNC)
68                 return 1;
69         /* same behaviour as i386. PAT always set to cached and MTRRs control the
70            caching behaviour. 
71            Hopefully a full PAT implementation will fix that soon. */      
72         return 0;
73 #elif defined(CONFIG_IA64)
74         /*
75          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
76          */
77         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
78 #else
79         /*
80          * Accessing memory above the top the kernel knows about or through a file pointer
81          * that was marked O_SYNC will be done non-cached.
82          */
83         if (file->f_flags & O_SYNC)
84                 return 1;
85         return addr >= __pa(high_memory);
86 #endif
87 }
88
89 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
90 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
91 {
92         if (addr + count > __pa(high_memory))
93                 return 0;
94
95         return 1;
96 }
97
98 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
99 {
100         return 1;
101 }
102 #endif
103
104 /*
105  * This funcion reads the *physical* memory. The f_pos points directly to the 
106  * memory location. 
107  */
108 static ssize_t read_mem(struct file * file, char __user * buf,
109                         size_t count, loff_t *ppos)
110 {
111         unsigned long p = *ppos;
112         ssize_t read, sz;
113         char *ptr;
114
115         if (!valid_phys_addr_range(p, count))
116                 return -EFAULT;
117         read = 0;
118 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
119         /* we don't have page 0 mapped on sparc and m68k.. */
120         if (p < PAGE_SIZE) {
121                 sz = PAGE_SIZE - p;
122                 if (sz > count) 
123                         sz = count; 
124                 if (sz > 0) {
125                         if (clear_user(buf, sz))
126                                 return -EFAULT;
127                         buf += sz; 
128                         p += sz; 
129                         count -= sz; 
130                         read += sz; 
131                 }
132         }
133 #endif
134
135         while (count > 0) {
136                 /*
137                  * Handle first page in case it's not aligned
138                  */
139                 if (-p & (PAGE_SIZE - 1))
140                         sz = -p & (PAGE_SIZE - 1);
141                 else
142                         sz = PAGE_SIZE;
143
144                 sz = min_t(unsigned long, sz, count);
145
146                 /*
147                  * On ia64 if a page has been mapped somewhere as
148                  * uncached, then it must also be accessed uncached
149                  * by the kernel or data corruption may occur
150                  */
151                 ptr = xlate_dev_mem_ptr(p);
152
153                 if (copy_to_user(buf, ptr, sz))
154                         return -EFAULT;
155                 buf += sz;
156                 p += sz;
157                 count -= sz;
158                 read += sz;
159         }
160
161         *ppos += read;
162         return read;
163 }
164
165 static ssize_t write_mem(struct file * file, const char __user * buf, 
166                          size_t count, loff_t *ppos)
167 {
168         unsigned long p = *ppos;
169         ssize_t written, sz;
170         unsigned long copied;
171         void *ptr;
172
173         if (!valid_phys_addr_range(p, count))
174                 return -EFAULT;
175
176         written = 0;
177
178 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
179         /* we don't have page 0 mapped on sparc and m68k.. */
180         if (p < PAGE_SIZE) {
181                 unsigned long sz = PAGE_SIZE - p;
182                 if (sz > count)
183                         sz = count;
184                 /* Hmm. Do something? */
185                 buf += sz;
186                 p += sz;
187                 count -= sz;
188                 written += sz;
189         }
190 #endif
191
192         while (count > 0) {
193                 /*
194                  * Handle first page in case it's not aligned
195                  */
196                 if (-p & (PAGE_SIZE - 1))
197                         sz = -p & (PAGE_SIZE - 1);
198                 else
199                         sz = PAGE_SIZE;
200
201                 sz = min_t(unsigned long, sz, count);
202
203                 /*
204                  * On ia64 if a page has been mapped somewhere as
205                  * uncached, then it must also be accessed uncached
206                  * by the kernel or data corruption may occur
207                  */
208                 ptr = xlate_dev_mem_ptr(p);
209
210                 copied = copy_from_user(ptr, buf, sz);
211                 if (copied) {
212                         written += sz - copied;
213                         if (written)
214                                 break;
215                         return -EFAULT;
216                 }
217                 buf += sz;
218                 p += sz;
219                 count -= sz;
220                 written += sz;
221         }
222
223         *ppos += written;
224         return written;
225 }
226
227 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
228 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
229                                      unsigned long size, pgprot_t vma_prot)
230 {
231 #ifdef pgprot_noncached
232         unsigned long offset = pfn << PAGE_SHIFT;
233
234         if (uncached_access(file, offset))
235                 return pgprot_noncached(vma_prot);
236 #endif
237         return vma_prot;
238 }
239 #endif
240
241 #ifndef CONFIG_MMU
242 static unsigned long get_unmapped_area_mem(struct file *file,
243                                            unsigned long addr,
244                                            unsigned long len,
245                                            unsigned long pgoff,
246                                            unsigned long flags)
247 {
248         if (!valid_mmap_phys_addr_range(pgoff, len))
249                 return (unsigned long) -EINVAL;
250         return pgoff << PAGE_SHIFT;
251 }
252
253 /* can't do an in-place private mapping if there's no MMU */
254 static inline int private_mapping_ok(struct vm_area_struct *vma)
255 {
256         return vma->vm_flags & VM_MAYSHARE;
257 }
258 #else
259 #define get_unmapped_area_mem   NULL
260
261 static inline int private_mapping_ok(struct vm_area_struct *vma)
262 {
263         return 1;
264 }
265 #endif
266
267 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
268 {
269         size_t size = vma->vm_end - vma->vm_start;
270
271         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
272                 return -EINVAL;
273
274         if (!private_mapping_ok(vma))
275                 return -ENOSYS;
276
277         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
278                                                  size,
279                                                  vma->vm_page_prot);
280
281         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
282         if (remap_pfn_range(vma,
283                             vma->vm_start,
284                             vma->vm_pgoff,
285                             size,
286                             vma->vm_page_prot))
287                 return -EAGAIN;
288         return 0;
289 }
290
291 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
292 {
293         unsigned long pfn;
294
295         /* Turn a kernel-virtual address into a physical page frame */
296         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
297
298         /*
299          * RED-PEN: on some architectures there is more mapped memory
300          * than available in mem_map which pfn_valid checks
301          * for. Perhaps should add a new macro here.
302          *
303          * RED-PEN: vmalloc is not supported right now.
304          */
305         if (!pfn_valid(pfn))
306                 return -EIO;
307
308         vma->vm_pgoff = pfn;
309         return mmap_mem(file, vma);
310 }
311
312 #ifdef CONFIG_CRASH_DUMP
313 /*
314  * Read memory corresponding to the old kernel.
315  */
316 static ssize_t read_oldmem(struct file *file, char __user *buf,
317                                 size_t count, loff_t *ppos)
318 {
319         unsigned long pfn, offset;
320         size_t read = 0, csize;
321         int rc = 0;
322
323         while (count) {
324                 pfn = *ppos / PAGE_SIZE;
325                 if (pfn > saved_max_pfn)
326                         return read;
327
328                 offset = (unsigned long)(*ppos % PAGE_SIZE);
329                 if (count > PAGE_SIZE - offset)
330                         csize = PAGE_SIZE - offset;
331                 else
332                         csize = count;
333
334                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
335                 if (rc < 0)
336                         return rc;
337                 buf += csize;
338                 *ppos += csize;
339                 read += csize;
340                 count -= csize;
341         }
342         return read;
343 }
344 #endif
345
346 extern long vread(char *buf, char *addr, unsigned long count);
347 extern long vwrite(char *buf, char *addr, unsigned long count);
348
349 /*
350  * This function reads the *virtual* memory as seen by the kernel.
351  */
352 static ssize_t read_kmem(struct file *file, char __user *buf, 
353                          size_t count, loff_t *ppos)
354 {
355         unsigned long p = *ppos;
356         ssize_t low_count, read, sz;
357         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
358
359         read = 0;
360         if (p < (unsigned long) high_memory) {
361                 low_count = count;
362                 if (count > (unsigned long) high_memory - p)
363                         low_count = (unsigned long) high_memory - p;
364
365 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
366                 /* we don't have page 0 mapped on sparc and m68k.. */
367                 if (p < PAGE_SIZE && low_count > 0) {
368                         size_t tmp = PAGE_SIZE - p;
369                         if (tmp > low_count) tmp = low_count;
370                         if (clear_user(buf, tmp))
371                                 return -EFAULT;
372                         buf += tmp;
373                         p += tmp;
374                         read += tmp;
375                         low_count -= tmp;
376                         count -= tmp;
377                 }
378 #endif
379                 while (low_count > 0) {
380                         /*
381                          * Handle first page in case it's not aligned
382                          */
383                         if (-p & (PAGE_SIZE - 1))
384                                 sz = -p & (PAGE_SIZE - 1);
385                         else
386                                 sz = PAGE_SIZE;
387
388                         sz = min_t(unsigned long, sz, low_count);
389
390                         /*
391                          * On ia64 if a page has been mapped somewhere as
392                          * uncached, then it must also be accessed uncached
393                          * by the kernel or data corruption may occur
394                          */
395                         kbuf = xlate_dev_kmem_ptr((char *)p);
396
397                         if (copy_to_user(buf, kbuf, sz))
398                                 return -EFAULT;
399                         buf += sz;
400                         p += sz;
401                         read += sz;
402                         low_count -= sz;
403                         count -= sz;
404                 }
405         }
406
407         if (count > 0) {
408                 kbuf = (char *)__get_free_page(GFP_KERNEL);
409                 if (!kbuf)
410                         return -ENOMEM;
411                 while (count > 0) {
412                         int len = count;
413
414                         if (len > PAGE_SIZE)
415                                 len = PAGE_SIZE;
416                         len = vread(kbuf, (char *)p, len);
417                         if (!len)
418                                 break;
419                         if (copy_to_user(buf, kbuf, len)) {
420                                 free_page((unsigned long)kbuf);
421                                 return -EFAULT;
422                         }
423                         count -= len;
424                         buf += len;
425                         read += len;
426                         p += len;
427                 }
428                 free_page((unsigned long)kbuf);
429         }
430         *ppos = p;
431         return read;
432 }
433
434
435 static inline ssize_t
436 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
437               size_t count, loff_t *ppos)
438 {
439         ssize_t written, sz;
440         unsigned long copied;
441
442         written = 0;
443 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
444         /* we don't have page 0 mapped on sparc and m68k.. */
445         if (realp < PAGE_SIZE) {
446                 unsigned long sz = PAGE_SIZE - realp;
447                 if (sz > count)
448                         sz = count;
449                 /* Hmm. Do something? */
450                 buf += sz;
451                 p += sz;
452                 realp += sz;
453                 count -= sz;
454                 written += sz;
455         }
456 #endif
457
458         while (count > 0) {
459                 char *ptr;
460                 /*
461                  * Handle first page in case it's not aligned
462                  */
463                 if (-realp & (PAGE_SIZE - 1))
464                         sz = -realp & (PAGE_SIZE - 1);
465                 else
466                         sz = PAGE_SIZE;
467
468                 sz = min_t(unsigned long, sz, count);
469
470                 /*
471                  * On ia64 if a page has been mapped somewhere as
472                  * uncached, then it must also be accessed uncached
473                  * by the kernel or data corruption may occur
474                  */
475                 ptr = xlate_dev_kmem_ptr(p);
476
477                 copied = copy_from_user(ptr, buf, sz);
478                 if (copied) {
479                         written += sz - copied;
480                         if (written)
481                                 break;
482                         return -EFAULT;
483                 }
484                 buf += sz;
485                 p += sz;
486                 realp += sz;
487                 count -= sz;
488                 written += sz;
489         }
490
491         *ppos += written;
492         return written;
493 }
494
495
496 /*
497  * This function writes to the *virtual* memory as seen by the kernel.
498  */
499 static ssize_t write_kmem(struct file * file, const char __user * buf, 
500                           size_t count, loff_t *ppos)
501 {
502         unsigned long p = *ppos;
503         ssize_t wrote = 0;
504         ssize_t virtr = 0;
505         ssize_t written;
506         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
507
508         if (p < (unsigned long) high_memory) {
509
510                 wrote = count;
511                 if (count > (unsigned long) high_memory - p)
512                         wrote = (unsigned long) high_memory - p;
513
514                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
515                 if (written != wrote)
516                         return written;
517                 wrote = written;
518                 p += wrote;
519                 buf += wrote;
520                 count -= wrote;
521         }
522
523         if (count > 0) {
524                 kbuf = (char *)__get_free_page(GFP_KERNEL);
525                 if (!kbuf)
526                         return wrote ? wrote : -ENOMEM;
527                 while (count > 0) {
528                         int len = count;
529
530                         if (len > PAGE_SIZE)
531                                 len = PAGE_SIZE;
532                         if (len) {
533                                 written = copy_from_user(kbuf, buf, len);
534                                 if (written) {
535                                         if (wrote + virtr)
536                                                 break;
537                                         free_page((unsigned long)kbuf);
538                                         return -EFAULT;
539                                 }
540                         }
541                         len = vwrite(kbuf, (char *)p, len);
542                         count -= len;
543                         buf += len;
544                         virtr += len;
545                         p += len;
546                 }
547                 free_page((unsigned long)kbuf);
548         }
549
550         *ppos = p;
551         return virtr + wrote;
552 }
553
554 #ifdef CONFIG_DEVPORT
555 static ssize_t read_port(struct file * file, char __user * buf,
556                          size_t count, loff_t *ppos)
557 {
558         unsigned long i = *ppos;
559         char __user *tmp = buf;
560
561         if (!access_ok(VERIFY_WRITE, buf, count))
562                 return -EFAULT; 
563         while (count-- > 0 && i < 65536) {
564                 if (__put_user(inb(i),tmp) < 0) 
565                         return -EFAULT;  
566                 i++;
567                 tmp++;
568         }
569         *ppos = i;
570         return tmp-buf;
571 }
572
573 static ssize_t write_port(struct file * file, const char __user * buf,
574                           size_t count, loff_t *ppos)
575 {
576         unsigned long i = *ppos;
577         const char __user * tmp = buf;
578
579         if (!access_ok(VERIFY_READ,buf,count))
580                 return -EFAULT;
581         while (count-- > 0 && i < 65536) {
582                 char c;
583                 if (__get_user(c, tmp)) {
584                         if (tmp > buf)
585                                 break;
586                         return -EFAULT; 
587                 }
588                 outb(c,i);
589                 i++;
590                 tmp++;
591         }
592         *ppos = i;
593         return tmp-buf;
594 }
595 #endif
596
597 static ssize_t read_null(struct file * file, char __user * buf,
598                          size_t count, loff_t *ppos)
599 {
600         return 0;
601 }
602
603 static ssize_t write_null(struct file * file, const char __user * buf,
604                           size_t count, loff_t *ppos)
605 {
606         return count;
607 }
608
609 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
610                         struct splice_desc *sd)
611 {
612         return sd->len;
613 }
614
615 static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
616                                  loff_t *ppos, size_t len, unsigned int flags)
617 {
618         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
619 }
620
621 #ifdef CONFIG_MMU
622 /*
623  * For fun, we are using the MMU for this.
624  */
625 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
626 {
627         struct mm_struct *mm;
628         struct vm_area_struct * vma;
629         unsigned long addr=(unsigned long)buf;
630
631         mm = current->mm;
632         /* Oops, this was forgotten before. -ben */
633         down_read(&mm->mmap_sem);
634
635         /* For private mappings, just map in zero pages. */
636         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
637                 unsigned long count;
638
639                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
640                         goto out_up;
641                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
642                         break;
643                 count = vma->vm_end - addr;
644                 if (count > size)
645                         count = size;
646
647                 zap_page_range(vma, addr, count, NULL);
648                 if (zeromap_page_range(vma, addr, count, PAGE_COPY))
649                         break;
650
651                 size -= count;
652                 buf += count;
653                 addr += count;
654                 if (size == 0)
655                         goto out_up;
656         }
657
658         up_read(&mm->mmap_sem);
659         
660         /* The shared case is hard. Let's do the conventional zeroing. */ 
661         do {
662                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
663                 if (unwritten)
664                         return size + unwritten - PAGE_SIZE;
665                 cond_resched();
666                 buf += PAGE_SIZE;
667                 size -= PAGE_SIZE;
668         } while (size);
669
670         return size;
671 out_up:
672         up_read(&mm->mmap_sem);
673         return size;
674 }
675
676 static ssize_t read_zero(struct file * file, char __user * buf, 
677                          size_t count, loff_t *ppos)
678 {
679         unsigned long left, unwritten, written = 0;
680
681         if (!count)
682                 return 0;
683
684         if (!access_ok(VERIFY_WRITE, buf, count))
685                 return -EFAULT;
686
687         left = count;
688
689         /* do we want to be clever? Arbitrary cut-off */
690         if (count >= PAGE_SIZE*4) {
691                 unsigned long partial;
692
693                 /* How much left of the page? */
694                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
695                 unwritten = clear_user(buf, partial);
696                 written = partial - unwritten;
697                 if (unwritten)
698                         goto out;
699                 left -= partial;
700                 buf += partial;
701                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
702                 written += (left & PAGE_MASK) - unwritten;
703                 if (unwritten)
704                         goto out;
705                 buf += left & PAGE_MASK;
706                 left &= ~PAGE_MASK;
707         }
708         unwritten = clear_user(buf, left);
709         written += left - unwritten;
710 out:
711         return written ? written : -EFAULT;
712 }
713
714 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
715 {
716         int err;
717
718         if (vma->vm_flags & VM_SHARED)
719                 return shmem_zero_setup(vma);
720         err = zeromap_page_range(vma, vma->vm_start,
721                         vma->vm_end - vma->vm_start, vma->vm_page_prot);
722         BUG_ON(err == -EEXIST);
723         return err;
724 }
725 #else /* CONFIG_MMU */
726 static ssize_t read_zero(struct file * file, char * buf, 
727                          size_t count, loff_t *ppos)
728 {
729         size_t todo = count;
730
731         while (todo) {
732                 size_t chunk = todo;
733
734                 if (chunk > 4096)
735                         chunk = 4096;   /* Just for latency reasons */
736                 if (clear_user(buf, chunk))
737                         return -EFAULT;
738                 buf += chunk;
739                 todo -= chunk;
740                 cond_resched();
741         }
742         return count;
743 }
744
745 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
746 {
747         return -ENOSYS;
748 }
749 #endif /* CONFIG_MMU */
750
751 static ssize_t write_full(struct file * file, const char __user * buf,
752                           size_t count, loff_t *ppos)
753 {
754         return -ENOSPC;
755 }
756
757 /*
758  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
759  * can fopen() both devices with "a" now.  This was previously impossible.
760  * -- SRB.
761  */
762
763 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
764 {
765         return file->f_pos = 0;
766 }
767
768 /*
769  * The memory devices use the full 32/64 bits of the offset, and so we cannot
770  * check against negative addresses: they are ok. The return value is weird,
771  * though, in that case (0).
772  *
773  * also note that seeking relative to the "end of file" isn't supported:
774  * it has no meaning, so it returns -EINVAL.
775  */
776 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
777 {
778         loff_t ret;
779
780         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
781         switch (orig) {
782                 case 0:
783                         file->f_pos = offset;
784                         ret = file->f_pos;
785                         force_successful_syscall_return();
786                         break;
787                 case 1:
788                         file->f_pos += offset;
789                         ret = file->f_pos;
790                         force_successful_syscall_return();
791                         break;
792                 default:
793                         ret = -EINVAL;
794         }
795         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
796         return ret;
797 }
798
799 static int open_port(struct inode * inode, struct file * filp)
800 {
801         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
802 }
803
804 #define zero_lseek      null_lseek
805 #define full_lseek      null_lseek
806 #define write_zero      write_null
807 #define read_full       read_zero
808 #define open_mem        open_port
809 #define open_kmem       open_mem
810 #define open_oldmem     open_mem
811
812 static const struct file_operations mem_fops = {
813         .llseek         = memory_lseek,
814         .read           = read_mem,
815         .write          = write_mem,
816         .mmap           = mmap_mem,
817         .open           = open_mem,
818         .get_unmapped_area = get_unmapped_area_mem,
819 };
820
821 static const struct file_operations kmem_fops = {
822         .llseek         = memory_lseek,
823         .read           = read_kmem,
824         .write          = write_kmem,
825         .mmap           = mmap_kmem,
826         .open           = open_kmem,
827         .get_unmapped_area = get_unmapped_area_mem,
828 };
829
830 static const struct file_operations null_fops = {
831         .llseek         = null_lseek,
832         .read           = read_null,
833         .write          = write_null,
834         .splice_write   = splice_write_null,
835 };
836
837 #ifdef CONFIG_DEVPORT
838 static const struct file_operations port_fops = {
839         .llseek         = memory_lseek,
840         .read           = read_port,
841         .write          = write_port,
842         .open           = open_port,
843 };
844 #endif
845
846 static const struct file_operations zero_fops = {
847         .llseek         = zero_lseek,
848         .read           = read_zero,
849         .write          = write_zero,
850         .mmap           = mmap_zero,
851 };
852
853 /*
854  * capabilities for /dev/zero
855  * - permits private mappings, "copies" are taken of the source of zeros
856  */
857 static struct backing_dev_info zero_bdi = {
858         .capabilities   = BDI_CAP_MAP_COPY,
859 };
860
861 static const struct file_operations full_fops = {
862         .llseek         = full_lseek,
863         .read           = read_full,
864         .write          = write_full,
865 };
866
867 #ifdef CONFIG_CRASH_DUMP
868 static const struct file_operations oldmem_fops = {
869         .read   = read_oldmem,
870         .open   = open_oldmem,
871 };
872 #endif
873
874 static ssize_t kmsg_write(struct file * file, const char __user * buf,
875                           size_t count, loff_t *ppos)
876 {
877         char *tmp;
878         ssize_t ret;
879
880         tmp = kmalloc(count + 1, GFP_KERNEL);
881         if (tmp == NULL)
882                 return -ENOMEM;
883         ret = -EFAULT;
884         if (!copy_from_user(tmp, buf, count)) {
885                 tmp[count] = 0;
886                 ret = printk("%s", tmp);
887                 if (ret > count)
888                         /* printk can add a prefix */
889                         ret = count;
890         }
891         kfree(tmp);
892         return ret;
893 }
894
895 static const struct file_operations kmsg_fops = {
896         .write =        kmsg_write,
897 };
898
899 static int memory_open(struct inode * inode, struct file * filp)
900 {
901         switch (iminor(inode)) {
902                 case 1:
903                         filp->f_op = &mem_fops;
904                         filp->f_mapping->backing_dev_info =
905                                 &directly_mappable_cdev_bdi;
906                         break;
907                 case 2:
908                         filp->f_op = &kmem_fops;
909                         filp->f_mapping->backing_dev_info =
910                                 &directly_mappable_cdev_bdi;
911                         break;
912                 case 3:
913                         filp->f_op = &null_fops;
914                         break;
915 #ifdef CONFIG_DEVPORT
916                 case 4:
917                         filp->f_op = &port_fops;
918                         break;
919 #endif
920                 case 5:
921                         filp->f_mapping->backing_dev_info = &zero_bdi;
922                         filp->f_op = &zero_fops;
923                         break;
924                 case 7:
925                         filp->f_op = &full_fops;
926                         break;
927                 case 8:
928                         filp->f_op = &random_fops;
929                         break;
930                 case 9:
931                         filp->f_op = &urandom_fops;
932                         break;
933                 case 11:
934                         filp->f_op = &kmsg_fops;
935                         break;
936 #ifdef CONFIG_CRASH_DUMP
937                 case 12:
938                         filp->f_op = &oldmem_fops;
939                         break;
940 #endif
941                 default:
942                         return -ENXIO;
943         }
944         if (filp->f_op && filp->f_op->open)
945                 return filp->f_op->open(inode,filp);
946         return 0;
947 }
948
949 static const struct file_operations memory_fops = {
950         .open           = memory_open,  /* just a selector for the real open */
951 };
952
953 static const struct {
954         unsigned int            minor;
955         char                    *name;
956         umode_t                 mode;
957         const struct file_operations    *fops;
958 } devlist[] = { /* list of minor devices */
959         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
960         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
961         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
962 #ifdef CONFIG_DEVPORT
963         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
964 #endif
965         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
966         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
967         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
968         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
969         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
970 #ifdef CONFIG_CRASH_DUMP
971         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
972 #endif
973 };
974
975 static struct class *mem_class;
976
977 static int __init chr_dev_init(void)
978 {
979         int i;
980
981         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
982                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
983
984         mem_class = class_create(THIS_MODULE, "mem");
985         for (i = 0; i < ARRAY_SIZE(devlist); i++)
986                 device_create(mem_class, NULL,
987                               MKDEV(MEM_MAJOR, devlist[i].minor),
988                               devlist[i].name);
989
990         return 0;
991 }
992
993 fs_initcall(chr_dev_init);