Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus
[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 #elif defined(CONFIG_MIPS)
79         {
80                 extern int __uncached_access(struct file *file,
81                                              unsigned long addr);
82
83                 return __uncached_access(file, addr);
84         }
85 #else
86         /*
87          * Accessing memory above the top the kernel knows about or through a file pointer
88          * that was marked O_SYNC will be done non-cached.
89          */
90         if (file->f_flags & O_SYNC)
91                 return 1;
92         return addr >= __pa(high_memory);
93 #endif
94 }
95
96 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
97 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
98 {
99         if (addr + count > __pa(high_memory))
100                 return 0;
101
102         return 1;
103 }
104
105 static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
106 {
107         return 1;
108 }
109 #endif
110
111 /*
112  * This funcion reads the *physical* memory. The f_pos points directly to the 
113  * memory location. 
114  */
115 static ssize_t read_mem(struct file * file, char __user * buf,
116                         size_t count, loff_t *ppos)
117 {
118         unsigned long p = *ppos;
119         ssize_t read, sz;
120         char *ptr;
121
122         if (!valid_phys_addr_range(p, count))
123                 return -EFAULT;
124         read = 0;
125 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
126         /* we don't have page 0 mapped on sparc and m68k.. */
127         if (p < PAGE_SIZE) {
128                 sz = PAGE_SIZE - p;
129                 if (sz > count) 
130                         sz = count; 
131                 if (sz > 0) {
132                         if (clear_user(buf, sz))
133                                 return -EFAULT;
134                         buf += sz; 
135                         p += sz; 
136                         count -= sz; 
137                         read += sz; 
138                 }
139         }
140 #endif
141
142         while (count > 0) {
143                 /*
144                  * Handle first page in case it's not aligned
145                  */
146                 if (-p & (PAGE_SIZE - 1))
147                         sz = -p & (PAGE_SIZE - 1);
148                 else
149                         sz = PAGE_SIZE;
150
151                 sz = min_t(unsigned long, sz, count);
152
153                 /*
154                  * On ia64 if a page has been mapped somewhere as
155                  * uncached, then it must also be accessed uncached
156                  * by the kernel or data corruption may occur
157                  */
158                 ptr = xlate_dev_mem_ptr(p);
159
160                 if (copy_to_user(buf, ptr, sz))
161                         return -EFAULT;
162                 buf += sz;
163                 p += sz;
164                 count -= sz;
165                 read += sz;
166         }
167
168         *ppos += read;
169         return read;
170 }
171
172 static ssize_t write_mem(struct file * file, const char __user * buf, 
173                          size_t count, loff_t *ppos)
174 {
175         unsigned long p = *ppos;
176         ssize_t written, sz;
177         unsigned long copied;
178         void *ptr;
179
180         if (!valid_phys_addr_range(p, count))
181                 return -EFAULT;
182
183         written = 0;
184
185 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
186         /* we don't have page 0 mapped on sparc and m68k.. */
187         if (p < PAGE_SIZE) {
188                 unsigned long sz = PAGE_SIZE - p;
189                 if (sz > count)
190                         sz = count;
191                 /* Hmm. Do something? */
192                 buf += sz;
193                 p += sz;
194                 count -= sz;
195                 written += sz;
196         }
197 #endif
198
199         while (count > 0) {
200                 /*
201                  * Handle first page in case it's not aligned
202                  */
203                 if (-p & (PAGE_SIZE - 1))
204                         sz = -p & (PAGE_SIZE - 1);
205                 else
206                         sz = PAGE_SIZE;
207
208                 sz = min_t(unsigned long, sz, count);
209
210                 /*
211                  * On ia64 if a page has been mapped somewhere as
212                  * uncached, then it must also be accessed uncached
213                  * by the kernel or data corruption may occur
214                  */
215                 ptr = xlate_dev_mem_ptr(p);
216
217                 copied = copy_from_user(ptr, buf, sz);
218                 if (copied) {
219                         written += sz - copied;
220                         if (written)
221                                 break;
222                         return -EFAULT;
223                 }
224                 buf += sz;
225                 p += sz;
226                 count -= sz;
227                 written += sz;
228         }
229
230         *ppos += written;
231         return written;
232 }
233
234 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
235 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
236                                      unsigned long size, pgprot_t vma_prot)
237 {
238 #ifdef pgprot_noncached
239         unsigned long offset = pfn << PAGE_SHIFT;
240
241         if (uncached_access(file, offset))
242                 return pgprot_noncached(vma_prot);
243 #endif
244         return vma_prot;
245 }
246 #endif
247
248 #ifndef CONFIG_MMU
249 static unsigned long get_unmapped_area_mem(struct file *file,
250                                            unsigned long addr,
251                                            unsigned long len,
252                                            unsigned long pgoff,
253                                            unsigned long flags)
254 {
255         if (!valid_mmap_phys_addr_range(pgoff, len))
256                 return (unsigned long) -EINVAL;
257         return pgoff << PAGE_SHIFT;
258 }
259
260 /* can't do an in-place private mapping if there's no MMU */
261 static inline int private_mapping_ok(struct vm_area_struct *vma)
262 {
263         return vma->vm_flags & VM_MAYSHARE;
264 }
265 #else
266 #define get_unmapped_area_mem   NULL
267
268 static inline int private_mapping_ok(struct vm_area_struct *vma)
269 {
270         return 1;
271 }
272 #endif
273
274 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
275 {
276         size_t size = vma->vm_end - vma->vm_start;
277
278         if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
279                 return -EINVAL;
280
281         if (!private_mapping_ok(vma))
282                 return -ENOSYS;
283
284         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
285                                                  size,
286                                                  vma->vm_page_prot);
287
288         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
289         if (remap_pfn_range(vma,
290                             vma->vm_start,
291                             vma->vm_pgoff,
292                             size,
293                             vma->vm_page_prot))
294                 return -EAGAIN;
295         return 0;
296 }
297
298 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
299 {
300         unsigned long pfn;
301
302         /* Turn a kernel-virtual address into a physical page frame */
303         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
304
305         /*
306          * RED-PEN: on some architectures there is more mapped memory
307          * than available in mem_map which pfn_valid checks
308          * for. Perhaps should add a new macro here.
309          *
310          * RED-PEN: vmalloc is not supported right now.
311          */
312         if (!pfn_valid(pfn))
313                 return -EIO;
314
315         vma->vm_pgoff = pfn;
316         return mmap_mem(file, vma);
317 }
318
319 #ifdef CONFIG_CRASH_DUMP
320 /*
321  * Read memory corresponding to the old kernel.
322  */
323 static ssize_t read_oldmem(struct file *file, char __user *buf,
324                                 size_t count, loff_t *ppos)
325 {
326         unsigned long pfn, offset;
327         size_t read = 0, csize;
328         int rc = 0;
329
330         while (count) {
331                 pfn = *ppos / PAGE_SIZE;
332                 if (pfn > saved_max_pfn)
333                         return read;
334
335                 offset = (unsigned long)(*ppos % PAGE_SIZE);
336                 if (count > PAGE_SIZE - offset)
337                         csize = PAGE_SIZE - offset;
338                 else
339                         csize = count;
340
341                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
342                 if (rc < 0)
343                         return rc;
344                 buf += csize;
345                 *ppos += csize;
346                 read += csize;
347                 count -= csize;
348         }
349         return read;
350 }
351 #endif
352
353 extern long vread(char *buf, char *addr, unsigned long count);
354 extern long vwrite(char *buf, char *addr, unsigned long count);
355
356 /*
357  * This function reads the *virtual* memory as seen by the kernel.
358  */
359 static ssize_t read_kmem(struct file *file, char __user *buf, 
360                          size_t count, loff_t *ppos)
361 {
362         unsigned long p = *ppos;
363         ssize_t low_count, read, sz;
364         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
365
366         read = 0;
367         if (p < (unsigned long) high_memory) {
368                 low_count = count;
369                 if (count > (unsigned long) high_memory - p)
370                         low_count = (unsigned long) high_memory - p;
371
372 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
373                 /* we don't have page 0 mapped on sparc and m68k.. */
374                 if (p < PAGE_SIZE && low_count > 0) {
375                         size_t tmp = PAGE_SIZE - p;
376                         if (tmp > low_count) tmp = low_count;
377                         if (clear_user(buf, tmp))
378                                 return -EFAULT;
379                         buf += tmp;
380                         p += tmp;
381                         read += tmp;
382                         low_count -= tmp;
383                         count -= tmp;
384                 }
385 #endif
386                 while (low_count > 0) {
387                         /*
388                          * Handle first page in case it's not aligned
389                          */
390                         if (-p & (PAGE_SIZE - 1))
391                                 sz = -p & (PAGE_SIZE - 1);
392                         else
393                                 sz = PAGE_SIZE;
394
395                         sz = min_t(unsigned long, sz, low_count);
396
397                         /*
398                          * On ia64 if a page has been mapped somewhere as
399                          * uncached, then it must also be accessed uncached
400                          * by the kernel or data corruption may occur
401                          */
402                         kbuf = xlate_dev_kmem_ptr((char *)p);
403
404                         if (copy_to_user(buf, kbuf, sz))
405                                 return -EFAULT;
406                         buf += sz;
407                         p += sz;
408                         read += sz;
409                         low_count -= sz;
410                         count -= sz;
411                 }
412         }
413
414         if (count > 0) {
415                 kbuf = (char *)__get_free_page(GFP_KERNEL);
416                 if (!kbuf)
417                         return -ENOMEM;
418                 while (count > 0) {
419                         int len = count;
420
421                         if (len > PAGE_SIZE)
422                                 len = PAGE_SIZE;
423                         len = vread(kbuf, (char *)p, len);
424                         if (!len)
425                                 break;
426                         if (copy_to_user(buf, kbuf, len)) {
427                                 free_page((unsigned long)kbuf);
428                                 return -EFAULT;
429                         }
430                         count -= len;
431                         buf += len;
432                         read += len;
433                         p += len;
434                 }
435                 free_page((unsigned long)kbuf);
436         }
437         *ppos = p;
438         return read;
439 }
440
441
442 static inline ssize_t
443 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
444               size_t count, loff_t *ppos)
445 {
446         ssize_t written, sz;
447         unsigned long copied;
448
449         written = 0;
450 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
451         /* we don't have page 0 mapped on sparc and m68k.. */
452         if (realp < PAGE_SIZE) {
453                 unsigned long sz = PAGE_SIZE - realp;
454                 if (sz > count)
455                         sz = count;
456                 /* Hmm. Do something? */
457                 buf += sz;
458                 p += sz;
459                 realp += sz;
460                 count -= sz;
461                 written += sz;
462         }
463 #endif
464
465         while (count > 0) {
466                 char *ptr;
467                 /*
468                  * Handle first page in case it's not aligned
469                  */
470                 if (-realp & (PAGE_SIZE - 1))
471                         sz = -realp & (PAGE_SIZE - 1);
472                 else
473                         sz = PAGE_SIZE;
474
475                 sz = min_t(unsigned long, sz, count);
476
477                 /*
478                  * On ia64 if a page has been mapped somewhere as
479                  * uncached, then it must also be accessed uncached
480                  * by the kernel or data corruption may occur
481                  */
482                 ptr = xlate_dev_kmem_ptr(p);
483
484                 copied = copy_from_user(ptr, buf, sz);
485                 if (copied) {
486                         written += sz - copied;
487                         if (written)
488                                 break;
489                         return -EFAULT;
490                 }
491                 buf += sz;
492                 p += sz;
493                 realp += sz;
494                 count -= sz;
495                 written += sz;
496         }
497
498         *ppos += written;
499         return written;
500 }
501
502
503 /*
504  * This function writes to the *virtual* memory as seen by the kernel.
505  */
506 static ssize_t write_kmem(struct file * file, const char __user * buf, 
507                           size_t count, loff_t *ppos)
508 {
509         unsigned long p = *ppos;
510         ssize_t wrote = 0;
511         ssize_t virtr = 0;
512         ssize_t written;
513         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
514
515         if (p < (unsigned long) high_memory) {
516
517                 wrote = count;
518                 if (count > (unsigned long) high_memory - p)
519                         wrote = (unsigned long) high_memory - p;
520
521                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
522                 if (written != wrote)
523                         return written;
524                 wrote = written;
525                 p += wrote;
526                 buf += wrote;
527                 count -= wrote;
528         }
529
530         if (count > 0) {
531                 kbuf = (char *)__get_free_page(GFP_KERNEL);
532                 if (!kbuf)
533                         return wrote ? wrote : -ENOMEM;
534                 while (count > 0) {
535                         int len = count;
536
537                         if (len > PAGE_SIZE)
538                                 len = PAGE_SIZE;
539                         if (len) {
540                                 written = copy_from_user(kbuf, buf, len);
541                                 if (written) {
542                                         if (wrote + virtr)
543                                                 break;
544                                         free_page((unsigned long)kbuf);
545                                         return -EFAULT;
546                                 }
547                         }
548                         len = vwrite(kbuf, (char *)p, len);
549                         count -= len;
550                         buf += len;
551                         virtr += len;
552                         p += len;
553                 }
554                 free_page((unsigned long)kbuf);
555         }
556
557         *ppos = p;
558         return virtr + wrote;
559 }
560
561 #ifdef CONFIG_DEVPORT
562 static ssize_t read_port(struct file * file, char __user * buf,
563                          size_t count, loff_t *ppos)
564 {
565         unsigned long i = *ppos;
566         char __user *tmp = buf;
567
568         if (!access_ok(VERIFY_WRITE, buf, count))
569                 return -EFAULT; 
570         while (count-- > 0 && i < 65536) {
571                 if (__put_user(inb(i),tmp) < 0) 
572                         return -EFAULT;  
573                 i++;
574                 tmp++;
575         }
576         *ppos = i;
577         return tmp-buf;
578 }
579
580 static ssize_t write_port(struct file * file, const char __user * buf,
581                           size_t count, loff_t *ppos)
582 {
583         unsigned long i = *ppos;
584         const char __user * tmp = buf;
585
586         if (!access_ok(VERIFY_READ,buf,count))
587                 return -EFAULT;
588         while (count-- > 0 && i < 65536) {
589                 char c;
590                 if (__get_user(c, tmp)) {
591                         if (tmp > buf)
592                                 break;
593                         return -EFAULT; 
594                 }
595                 outb(c,i);
596                 i++;
597                 tmp++;
598         }
599         *ppos = i;
600         return tmp-buf;
601 }
602 #endif
603
604 static ssize_t read_null(struct file * file, char __user * buf,
605                          size_t count, loff_t *ppos)
606 {
607         return 0;
608 }
609
610 static ssize_t write_null(struct file * file, const char __user * buf,
611                           size_t count, loff_t *ppos)
612 {
613         return count;
614 }
615
616 static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
617                         struct splice_desc *sd)
618 {
619         return sd->len;
620 }
621
622 static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
623                                  loff_t *ppos, size_t len, unsigned int flags)
624 {
625         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
626 }
627
628 #ifdef CONFIG_MMU
629 /*
630  * For fun, we are using the MMU for this.
631  */
632 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
633 {
634         struct mm_struct *mm;
635         struct vm_area_struct * vma;
636         unsigned long addr=(unsigned long)buf;
637
638         mm = current->mm;
639         /* Oops, this was forgotten before. -ben */
640         down_read(&mm->mmap_sem);
641
642         /* For private mappings, just map in zero pages. */
643         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
644                 unsigned long count;
645
646                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
647                         goto out_up;
648                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
649                         break;
650                 count = vma->vm_end - addr;
651                 if (count > size)
652                         count = size;
653
654                 zap_page_range(vma, addr, count, NULL);
655                 if (zeromap_page_range(vma, addr, count, PAGE_COPY))
656                         break;
657
658                 size -= count;
659                 buf += count;
660                 addr += count;
661                 if (size == 0)
662                         goto out_up;
663         }
664
665         up_read(&mm->mmap_sem);
666         
667         /* The shared case is hard. Let's do the conventional zeroing. */ 
668         do {
669                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
670                 if (unwritten)
671                         return size + unwritten - PAGE_SIZE;
672                 cond_resched();
673                 buf += PAGE_SIZE;
674                 size -= PAGE_SIZE;
675         } while (size);
676
677         return size;
678 out_up:
679         up_read(&mm->mmap_sem);
680         return size;
681 }
682
683 static ssize_t read_zero(struct file * file, char __user * buf, 
684                          size_t count, loff_t *ppos)
685 {
686         unsigned long left, unwritten, written = 0;
687
688         if (!count)
689                 return 0;
690
691         if (!access_ok(VERIFY_WRITE, buf, count))
692                 return -EFAULT;
693
694         left = count;
695
696         /* do we want to be clever? Arbitrary cut-off */
697         if (count >= PAGE_SIZE*4) {
698                 unsigned long partial;
699
700                 /* How much left of the page? */
701                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
702                 unwritten = clear_user(buf, partial);
703                 written = partial - unwritten;
704                 if (unwritten)
705                         goto out;
706                 left -= partial;
707                 buf += partial;
708                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
709                 written += (left & PAGE_MASK) - unwritten;
710                 if (unwritten)
711                         goto out;
712                 buf += left & PAGE_MASK;
713                 left &= ~PAGE_MASK;
714         }
715         unwritten = clear_user(buf, left);
716         written += left - unwritten;
717 out:
718         return written ? written : -EFAULT;
719 }
720
721 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
722 {
723         int err;
724
725         if (vma->vm_flags & VM_SHARED)
726                 return shmem_zero_setup(vma);
727         err = zeromap_page_range(vma, vma->vm_start,
728                         vma->vm_end - vma->vm_start, vma->vm_page_prot);
729         BUG_ON(err == -EEXIST);
730         return err;
731 }
732 #else /* CONFIG_MMU */
733 static ssize_t read_zero(struct file * file, char * buf, 
734                          size_t count, loff_t *ppos)
735 {
736         size_t todo = count;
737
738         while (todo) {
739                 size_t chunk = todo;
740
741                 if (chunk > 4096)
742                         chunk = 4096;   /* Just for latency reasons */
743                 if (clear_user(buf, chunk))
744                         return -EFAULT;
745                 buf += chunk;
746                 todo -= chunk;
747                 cond_resched();
748         }
749         return count;
750 }
751
752 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
753 {
754         return -ENOSYS;
755 }
756 #endif /* CONFIG_MMU */
757
758 static ssize_t write_full(struct file * file, const char __user * buf,
759                           size_t count, loff_t *ppos)
760 {
761         return -ENOSPC;
762 }
763
764 /*
765  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
766  * can fopen() both devices with "a" now.  This was previously impossible.
767  * -- SRB.
768  */
769
770 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
771 {
772         return file->f_pos = 0;
773 }
774
775 /*
776  * The memory devices use the full 32/64 bits of the offset, and so we cannot
777  * check against negative addresses: they are ok. The return value is weird,
778  * though, in that case (0).
779  *
780  * also note that seeking relative to the "end of file" isn't supported:
781  * it has no meaning, so it returns -EINVAL.
782  */
783 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
784 {
785         loff_t ret;
786
787         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
788         switch (orig) {
789                 case 0:
790                         file->f_pos = offset;
791                         ret = file->f_pos;
792                         force_successful_syscall_return();
793                         break;
794                 case 1:
795                         file->f_pos += offset;
796                         ret = file->f_pos;
797                         force_successful_syscall_return();
798                         break;
799                 default:
800                         ret = -EINVAL;
801         }
802         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
803         return ret;
804 }
805
806 static int open_port(struct inode * inode, struct file * filp)
807 {
808         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
809 }
810
811 #define zero_lseek      null_lseek
812 #define full_lseek      null_lseek
813 #define write_zero      write_null
814 #define read_full       read_zero
815 #define open_mem        open_port
816 #define open_kmem       open_mem
817 #define open_oldmem     open_mem
818
819 static const struct file_operations mem_fops = {
820         .llseek         = memory_lseek,
821         .read           = read_mem,
822         .write          = write_mem,
823         .mmap           = mmap_mem,
824         .open           = open_mem,
825         .get_unmapped_area = get_unmapped_area_mem,
826 };
827
828 static const struct file_operations kmem_fops = {
829         .llseek         = memory_lseek,
830         .read           = read_kmem,
831         .write          = write_kmem,
832         .mmap           = mmap_kmem,
833         .open           = open_kmem,
834         .get_unmapped_area = get_unmapped_area_mem,
835 };
836
837 static const struct file_operations null_fops = {
838         .llseek         = null_lseek,
839         .read           = read_null,
840         .write          = write_null,
841         .splice_write   = splice_write_null,
842 };
843
844 #ifdef CONFIG_DEVPORT
845 static const struct file_operations port_fops = {
846         .llseek         = memory_lseek,
847         .read           = read_port,
848         .write          = write_port,
849         .open           = open_port,
850 };
851 #endif
852
853 static const struct file_operations zero_fops = {
854         .llseek         = zero_lseek,
855         .read           = read_zero,
856         .write          = write_zero,
857         .mmap           = mmap_zero,
858 };
859
860 /*
861  * capabilities for /dev/zero
862  * - permits private mappings, "copies" are taken of the source of zeros
863  */
864 static struct backing_dev_info zero_bdi = {
865         .capabilities   = BDI_CAP_MAP_COPY,
866 };
867
868 static const struct file_operations full_fops = {
869         .llseek         = full_lseek,
870         .read           = read_full,
871         .write          = write_full,
872 };
873
874 #ifdef CONFIG_CRASH_DUMP
875 static const struct file_operations oldmem_fops = {
876         .read   = read_oldmem,
877         .open   = open_oldmem,
878 };
879 #endif
880
881 static ssize_t kmsg_write(struct file * file, const char __user * buf,
882                           size_t count, loff_t *ppos)
883 {
884         char *tmp;
885         ssize_t ret;
886
887         tmp = kmalloc(count + 1, GFP_KERNEL);
888         if (tmp == NULL)
889                 return -ENOMEM;
890         ret = -EFAULT;
891         if (!copy_from_user(tmp, buf, count)) {
892                 tmp[count] = 0;
893                 ret = printk("%s", tmp);
894                 if (ret > count)
895                         /* printk can add a prefix */
896                         ret = count;
897         }
898         kfree(tmp);
899         return ret;
900 }
901
902 static const struct file_operations kmsg_fops = {
903         .write =        kmsg_write,
904 };
905
906 static int memory_open(struct inode * inode, struct file * filp)
907 {
908         switch (iminor(inode)) {
909                 case 1:
910                         filp->f_op = &mem_fops;
911                         filp->f_mapping->backing_dev_info =
912                                 &directly_mappable_cdev_bdi;
913                         break;
914                 case 2:
915                         filp->f_op = &kmem_fops;
916                         filp->f_mapping->backing_dev_info =
917                                 &directly_mappable_cdev_bdi;
918                         break;
919                 case 3:
920                         filp->f_op = &null_fops;
921                         break;
922 #ifdef CONFIG_DEVPORT
923                 case 4:
924                         filp->f_op = &port_fops;
925                         break;
926 #endif
927                 case 5:
928                         filp->f_mapping->backing_dev_info = &zero_bdi;
929                         filp->f_op = &zero_fops;
930                         break;
931                 case 7:
932                         filp->f_op = &full_fops;
933                         break;
934                 case 8:
935                         filp->f_op = &random_fops;
936                         break;
937                 case 9:
938                         filp->f_op = &urandom_fops;
939                         break;
940                 case 11:
941                         filp->f_op = &kmsg_fops;
942                         break;
943 #ifdef CONFIG_CRASH_DUMP
944                 case 12:
945                         filp->f_op = &oldmem_fops;
946                         break;
947 #endif
948                 default:
949                         return -ENXIO;
950         }
951         if (filp->f_op && filp->f_op->open)
952                 return filp->f_op->open(inode,filp);
953         return 0;
954 }
955
956 static const struct file_operations memory_fops = {
957         .open           = memory_open,  /* just a selector for the real open */
958 };
959
960 static const struct {
961         unsigned int            minor;
962         char                    *name;
963         umode_t                 mode;
964         const struct file_operations    *fops;
965 } devlist[] = { /* list of minor devices */
966         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
967         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
968         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
969 #ifdef CONFIG_DEVPORT
970         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
971 #endif
972         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
973         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
974         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
975         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
976         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
977 #ifdef CONFIG_CRASH_DUMP
978         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
979 #endif
980 };
981
982 static struct class *mem_class;
983
984 static int __init chr_dev_init(void)
985 {
986         int i;
987
988         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
989                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
990
991         mem_class = class_create(THIS_MODULE, "mem");
992         for (i = 0; i < ARRAY_SIZE(devlist); i++)
993                 device_create(mem_class, NULL,
994                               MKDEV(MEM_MAJOR, devlist[i].minor),
995                               devlist[i].name);
996
997         return 0;
998 }
999
1000 fs_initcall(chr_dev_init);