Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  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__) && !defined(__arch_um__)
 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__) && !defined(__arch_um__)
 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 static ssize_t read_zero(struct file * file, char __user * buf, 
629                          size_t count, loff_t *ppos)
630 {
631         size_t written;
632 
633         if (!count)
634                 return 0;
635 
636         if (!access_ok(VERIFY_WRITE, buf, count))
637                 return -EFAULT;
638 
639         written = 0;
640         while (count) {
641                 unsigned long unwritten;
642                 size_t chunk = count;
643 
644                 if (chunk > PAGE_SIZE)
645                         chunk = PAGE_SIZE;      /* Just for latency reasons */
646                 unwritten = clear_user(buf, chunk);
647                 written += chunk - unwritten;
648                 if (unwritten)
649                         break;
650                 buf += chunk;
651                 count -= chunk;
652                 cond_resched();
653         }
654         return written ? written : -EFAULT;
655 }
656 
657 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
658 {
659 #ifndef CONFIG_MMU
660         return -ENOSYS;
661 #endif
662         if (vma->vm_flags & VM_SHARED)
663                 return shmem_zero_setup(vma);
664         return 0;
665 }
666 
667 static ssize_t write_full(struct file * file, const char __user * buf,
668                           size_t count, loff_t *ppos)
669 {
670         return -ENOSPC;
671 }
672 
673 /*
674  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
675  * can fopen() both devices with "a" now.  This was previously impossible.
676  * -- SRB.
677  */
678 
679 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
680 {
681         return file->f_pos = 0;
682 }
683 
684 /*
685  * The memory devices use the full 32/64 bits of the offset, and so we cannot
686  * check against negative addresses: they are ok. The return value is weird,
687  * though, in that case (0).
688  *
689  * also note that seeking relative to the "end of file" isn't supported:
690  * it has no meaning, so it returns -EINVAL.
691  */
692 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
693 {
694         loff_t ret;
695 
696         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
697         switch (orig) {
698                 case 0:
699                         file->f_pos = offset;
700                         ret = file->f_pos;
701                         force_successful_syscall_return();
702                         break;
703                 case 1:
704                         file->f_pos += offset;
705                         ret = file->f_pos;
706                         force_successful_syscall_return();
707                         break;
708                 default:
709                         ret = -EINVAL;
710         }
711         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
712         return ret;
713 }
714 
715 static int open_port(struct inode * inode, struct file * filp)
716 {
717         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
718 }
719 
720 #define zero_lseek      null_lseek
721 #define full_lseek      null_lseek
722 #define write_zero      write_null
723 #define read_full       read_zero
724 #define open_mem        open_port
725 #define open_kmem       open_mem
726 #define open_oldmem     open_mem
727 
728 static const struct file_operations mem_fops = {
729         .llseek         = memory_lseek,
730         .read           = read_mem,
731         .write          = write_mem,
732         .mmap           = mmap_mem,
733         .open           = open_mem,
734         .get_unmapped_area = get_unmapped_area_mem,
735 };
736 
737 static const struct file_operations kmem_fops = {
738         .llseek         = memory_lseek,
739         .read           = read_kmem,
740         .write          = write_kmem,
741         .mmap           = mmap_kmem,
742         .open           = open_kmem,
743         .get_unmapped_area = get_unmapped_area_mem,
744 };
745 
746 static const struct file_operations null_fops = {
747         .llseek         = null_lseek,
748         .read           = read_null,
749         .write          = write_null,
750         .splice_write   = splice_write_null,
751 };
752 
753 #ifdef CONFIG_DEVPORT
754 static const struct file_operations port_fops = {
755         .llseek         = memory_lseek,
756         .read           = read_port,
757         .write          = write_port,
758         .open           = open_port,
759 };
760 #endif
761 
762 static const struct file_operations zero_fops = {
763         .llseek         = zero_lseek,
764         .read           = read_zero,
765         .write          = write_zero,
766         .mmap           = mmap_zero,
767 };
768 
769 /*
770  * capabilities for /dev/zero
771  * - permits private mappings, "copies" are taken of the source of zeros
772  */
773 static struct backing_dev_info zero_bdi = {
774         .capabilities   = BDI_CAP_MAP_COPY,
775 };
776 
777 static const struct file_operations full_fops = {
778         .llseek         = full_lseek,
779         .read           = read_full,
780         .write          = write_full,
781 };
782 
783 #ifdef CONFIG_CRASH_DUMP
784 static const struct file_operations oldmem_fops = {
785         .read   = read_oldmem,
786         .open   = open_oldmem,
787 };
788 #endif
789 
790 static ssize_t kmsg_write(struct file * file, const char __user * buf,
791                           size_t count, loff_t *ppos)
792 {
793         char *tmp;
794         ssize_t ret;
795 
796         tmp = kmalloc(count + 1, GFP_KERNEL);
797         if (tmp == NULL)
798                 return -ENOMEM;
799         ret = -EFAULT;
800         if (!copy_from_user(tmp, buf, count)) {
801                 tmp[count] = 0;
802                 ret = printk("%s", tmp);
803                 if (ret > count)
804                         /* printk can add a prefix */
805                         ret = count;
806         }
807         kfree(tmp);
808         return ret;
809 }
810 
811 static const struct file_operations kmsg_fops = {
812         .write =        kmsg_write,
813 };
814 
815 static int memory_open(struct inode * inode, struct file * filp)
816 {
817         switch (iminor(inode)) {
818                 case 1:
819                         filp->f_op = &mem_fops;
820                         filp->f_mapping->backing_dev_info =
821                                 &directly_mappable_cdev_bdi;
822                         break;
823                 case 2:
824                         filp->f_op = &kmem_fops;
825                         filp->f_mapping->backing_dev_info =
826                                 &directly_mappable_cdev_bdi;
827                         break;
828                 case 3:
829                         filp->f_op = &null_fops;
830                         break;
831 #ifdef CONFIG_DEVPORT
832                 case 4:
833                         filp->f_op = &port_fops;
834                         break;
835 #endif
836                 case 5:
837                         filp->f_mapping->backing_dev_info = &zero_bdi;
838                         filp->f_op = &zero_fops;
839                         break;
840                 case 7:
841                         filp->f_op = &full_fops;
842                         break;
843                 case 8:
844                         filp->f_op = &random_fops;
845                         break;
846                 case 9:
847                         filp->f_op = &urandom_fops;
848                         break;
849                 case 11:
850                         filp->f_op = &kmsg_fops;
851                         break;
852 #ifdef CONFIG_CRASH_DUMP
853                 case 12:
854                         filp->f_op = &oldmem_fops;
855                         break;
856 #endif
857                 default:
858                         return -ENXIO;
859         }
860         if (filp->f_op && filp->f_op->open)
861                 return filp->f_op->open(inode,filp);
862         return 0;
863 }
864 
865 static const struct file_operations memory_fops = {
866         .open           = memory_open,  /* just a selector for the real open */
867 };
868 
869 static const struct {
870         unsigned int            minor;
871         char                    *name;
872         umode_t                 mode;
873         const struct file_operations    *fops;
874 } devlist[] = { /* list of minor devices */
875         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
876         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
877         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
878 #ifdef CONFIG_DEVPORT
879         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
880 #endif
881         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
882         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
883         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
884         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
885         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
886 #ifdef CONFIG_CRASH_DUMP
887         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
888 #endif
889 };
890 
891 static struct class *mem_class;
892 
893 static int __init chr_dev_init(void)
894 {
895         int i;
896         int err;
897 
898         err = bdi_init(&zero_bdi);
899         if (err)
900                 return err;
901 
902         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
903                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
904 
905         mem_class = class_create(THIS_MODULE, "mem");
906         for (i = 0; i < ARRAY_SIZE(devlist); i++)
907                 device_create(mem_class, NULL,
908                               MKDEV(MEM_MAJOR, devlist[i].minor),
909                               devlist[i].name);
910 
911         return 0;
912 }
913 
914 fs_initcall(chr_dev_init);
915 
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