blob: f5c160caf9f480978db2cb0698192268433370ae [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#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/smp_lock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/ptrace.h>
23#include <linux/device.h>
Vivek Goyal50b1fdb2005-06-25 14:58:23 -070024#include <linux/highmem.h>
25#include <linux/crash_dump.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/backing-dev.h>
Vivek Goyal315c2152005-06-25 14:58:24 -070027#include <linux/bootmem.h>
Jens Axboe1ebd32f2006-04-26 14:40:08 +020028#include <linux/pipe_fs_i.h>
Linus Torvaldsb8a3ad52006-10-13 08:42:10 -070029#include <linux/pfn.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
31#include <asm/uaccess.h>
32#include <asm/io.h>
33
34#ifdef CONFIG_IA64
35# include <linux/efi.h>
36#endif
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038/*
39 * Architectures vary in how they handle caching for addresses
40 * outside of main memory.
41 *
42 */
43static inline int uncached_access(struct file *file, unsigned long addr)
44{
45#if defined(__i386__)
46 /*
47 * On the PPro and successors, the MTRRs are used to set
48 * memory types for physical addresses outside main memory,
49 * so blindly setting PCD or PWT on those pages is wrong.
50 * For Pentiums and earlier, the surround logic should disable
51 * caching for the high addresses through the KEN pin, but
52 * we maintain the tradition of paranoia in this code.
53 */
54 if (file->f_flags & O_SYNC)
55 return 1;
56 return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
57 test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
58 test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
59 test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
60 && addr >= __pa(high_memory);
61#elif defined(__x86_64__)
62 /*
63 * This is broken because it can generate memory type aliases,
64 * which can cause cache corruptions
65 * But it is only available for root and we have to be bug-to-bug
66 * compatible with i386.
67 */
68 if (file->f_flags & O_SYNC)
69 return 1;
70 /* same behaviour as i386. PAT always set to cached and MTRRs control the
71 caching behaviour.
72 Hopefully a full PAT implementation will fix that soon. */
73 return 0;
74#elif defined(CONFIG_IA64)
75 /*
76 * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
77 */
78 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
79#else
80 /*
81 * Accessing memory above the top the kernel knows about or through a file pointer
82 * that was marked O_SYNC will be done non-cached.
83 */
84 if (file->f_flags & O_SYNC)
85 return 1;
86 return addr >= __pa(high_memory);
87#endif
88}
89
90#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
Bjorn Helgaas136939a2006-03-26 01:37:05 -080091static inline int valid_phys_addr_range(unsigned long addr, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -070092{
Bjorn Helgaas136939a2006-03-26 01:37:05 -080093 if (addr + count > __pa(high_memory))
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 return 0;
95
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 return 1;
97}
Bjorn Helgaas80851ef2006-01-08 01:04:13 -080098
Lennert Buytenhek06c67be2006-07-10 04:45:27 -070099static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800100{
101 return 1;
102}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103#endif
104
105/*
106 * This funcion reads the *physical* memory. The f_pos points directly to the
107 * memory location.
108 */
109static ssize_t read_mem(struct file * file, char __user * buf,
110 size_t count, loff_t *ppos)
111{
112 unsigned long p = *ppos;
113 ssize_t read, sz;
114 char *ptr;
115
Bjorn Helgaas136939a2006-03-26 01:37:05 -0800116 if (!valid_phys_addr_range(p, count))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 return -EFAULT;
118 read = 0;
119#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
120 /* we don't have page 0 mapped on sparc and m68k.. */
121 if (p < PAGE_SIZE) {
122 sz = PAGE_SIZE - p;
123 if (sz > count)
124 sz = count;
125 if (sz > 0) {
126 if (clear_user(buf, sz))
127 return -EFAULT;
128 buf += sz;
129 p += sz;
130 count -= sz;
131 read += sz;
132 }
133 }
134#endif
135
136 while (count > 0) {
137 /*
138 * Handle first page in case it's not aligned
139 */
140 if (-p & (PAGE_SIZE - 1))
141 sz = -p & (PAGE_SIZE - 1);
142 else
143 sz = PAGE_SIZE;
144
145 sz = min_t(unsigned long, sz, count);
146
147 /*
148 * On ia64 if a page has been mapped somewhere as
149 * uncached, then it must also be accessed uncached
150 * by the kernel or data corruption may occur
151 */
152 ptr = xlate_dev_mem_ptr(p);
153
154 if (copy_to_user(buf, ptr, sz))
155 return -EFAULT;
156 buf += sz;
157 p += sz;
158 count -= sz;
159 read += sz;
160 }
161
162 *ppos += read;
163 return read;
164}
165
166static ssize_t write_mem(struct file * file, const char __user * buf,
167 size_t count, loff_t *ppos)
168{
169 unsigned long p = *ppos;
170 ssize_t written, sz;
171 unsigned long copied;
172 void *ptr;
173
Bjorn Helgaas136939a2006-03-26 01:37:05 -0800174 if (!valid_phys_addr_range(p, count))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 return -EFAULT;
176
177 written = 0;
178
179#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
180 /* we don't have page 0 mapped on sparc and m68k.. */
181 if (p < PAGE_SIZE) {
182 unsigned long sz = PAGE_SIZE - p;
183 if (sz > count)
184 sz = count;
185 /* Hmm. Do something? */
186 buf += sz;
187 p += sz;
188 count -= sz;
189 written += sz;
190 }
191#endif
192
193 while (count > 0) {
194 /*
195 * Handle first page in case it's not aligned
196 */
197 if (-p & (PAGE_SIZE - 1))
198 sz = -p & (PAGE_SIZE - 1);
199 else
200 sz = PAGE_SIZE;
201
202 sz = min_t(unsigned long, sz, count);
203
204 /*
205 * On ia64 if a page has been mapped somewhere as
206 * uncached, then it must also be accessed uncached
207 * by the kernel or data corruption may occur
208 */
209 ptr = xlate_dev_mem_ptr(p);
210
211 copied = copy_from_user(ptr, buf, sz);
212 if (copied) {
Jan Beulichc654d602006-03-25 03:07:31 -0800213 written += sz - copied;
214 if (written)
215 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 return -EFAULT;
217 }
218 buf += sz;
219 p += sz;
220 count -= sz;
221 written += sz;
222 }
223
224 *ppos += written;
225 return written;
226}
227
Bjorn Helgaas44ac8412006-01-08 01:04:10 -0800228#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
229static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
230 unsigned long size, pgprot_t vma_prot)
231{
232#ifdef pgprot_noncached
233 unsigned long offset = pfn << PAGE_SHIFT;
234
235 if (uncached_access(file, offset))
236 return pgprot_noncached(vma_prot);
237#endif
238 return vma_prot;
239}
240#endif
241
David Howells5da61852006-09-27 01:50:16 -0700242#ifndef CONFIG_MMU
243static unsigned long get_unmapped_area_mem(struct file *file,
244 unsigned long addr,
245 unsigned long len,
246 unsigned long pgoff,
247 unsigned long flags)
248{
249 if (!valid_mmap_phys_addr_range(pgoff, len))
250 return (unsigned long) -EINVAL;
251 return pgoff;
252}
253
254/* can't do an in-place private mapping if there's no MMU */
255static inline int private_mapping_ok(struct vm_area_struct *vma)
256{
257 return vma->vm_flags & VM_MAYSHARE;
258}
259#else
260#define get_unmapped_area_mem NULL
261
262static inline int private_mapping_ok(struct vm_area_struct *vma)
263{
264 return 1;
265}
266#endif
267
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268static int mmap_mem(struct file * file, struct vm_area_struct * vma)
269{
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800270 size_t size = vma->vm_end - vma->vm_start;
271
Lennert Buytenhek06c67be2006-07-10 04:45:27 -0700272 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800273 return -EINVAL;
274
David Howells5da61852006-09-27 01:50:16 -0700275 if (!private_mapping_ok(vma))
276 return -ENOSYS;
277
Roland Dreier8b150472005-10-28 17:46:18 -0700278 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800279 size,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 vma->vm_page_prot);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
282 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
283 if (remap_pfn_range(vma,
284 vma->vm_start,
285 vma->vm_pgoff,
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800286 size,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 vma->vm_page_prot))
288 return -EAGAIN;
289 return 0;
290}
291
292static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
293{
Linus Torvalds4bb82552005-08-13 14:22:59 -0700294 unsigned long pfn;
295
Linus Torvalds6d3154c2007-01-22 08:53:24 -0800296 /* Turn a kernel-virtual address into a physical page frame */
297 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
Linus Torvalds4bb82552005-08-13 14:22:59 -0700298
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 /*
300 * RED-PEN: on some architectures there is more mapped memory
301 * than available in mem_map which pfn_valid checks
302 * for. Perhaps should add a new macro here.
303 *
304 * RED-PEN: vmalloc is not supported right now.
305 */
Linus Torvalds4bb82552005-08-13 14:22:59 -0700306 if (!pfn_valid(pfn))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 return -EIO;
Linus Torvalds4bb82552005-08-13 14:22:59 -0700308
309 vma->vm_pgoff = pfn;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 return mmap_mem(file, vma);
311}
312
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700313#ifdef CONFIG_CRASH_DUMP
314/*
315 * Read memory corresponding to the old kernel.
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700316 */
Vivek Goyal315c2152005-06-25 14:58:24 -0700317static ssize_t read_oldmem(struct file *file, char __user *buf,
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700318 size_t count, loff_t *ppos)
319{
Vivek Goyal315c2152005-06-25 14:58:24 -0700320 unsigned long pfn, offset;
321 size_t read = 0, csize;
322 int rc = 0;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700323
Maneesh Soni72414d32005-06-25 14:58:28 -0700324 while (count) {
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700325 pfn = *ppos / PAGE_SIZE;
Vivek Goyal315c2152005-06-25 14:58:24 -0700326 if (pfn > saved_max_pfn)
327 return read;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700328
Vivek Goyal315c2152005-06-25 14:58:24 -0700329 offset = (unsigned long)(*ppos % PAGE_SIZE);
330 if (count > PAGE_SIZE - offset)
331 csize = PAGE_SIZE - offset;
332 else
333 csize = count;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700334
Vivek Goyal315c2152005-06-25 14:58:24 -0700335 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
336 if (rc < 0)
337 return rc;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700338 buf += csize;
339 *ppos += csize;
340 read += csize;
341 count -= csize;
342 }
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700343 return read;
344}
345#endif
346
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347extern long vread(char *buf, char *addr, unsigned long count);
348extern long vwrite(char *buf, char *addr, unsigned long count);
349
350/*
351 * This function reads the *virtual* memory as seen by the kernel.
352 */
353static ssize_t read_kmem(struct file *file, char __user *buf,
354 size_t count, loff_t *ppos)
355{
356 unsigned long p = *ppos;
357 ssize_t low_count, read, sz;
358 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
359
360 read = 0;
361 if (p < (unsigned long) high_memory) {
362 low_count = count;
363 if (count > (unsigned long) high_memory - p)
364 low_count = (unsigned long) high_memory - p;
365
366#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
367 /* we don't have page 0 mapped on sparc and m68k.. */
368 if (p < PAGE_SIZE && low_count > 0) {
369 size_t tmp = PAGE_SIZE - p;
370 if (tmp > low_count) tmp = low_count;
371 if (clear_user(buf, tmp))
372 return -EFAULT;
373 buf += tmp;
374 p += tmp;
375 read += tmp;
376 low_count -= tmp;
377 count -= tmp;
378 }
379#endif
380 while (low_count > 0) {
381 /*
382 * Handle first page in case it's not aligned
383 */
384 if (-p & (PAGE_SIZE - 1))
385 sz = -p & (PAGE_SIZE - 1);
386 else
387 sz = PAGE_SIZE;
388
389 sz = min_t(unsigned long, sz, low_count);
390
391 /*
392 * On ia64 if a page has been mapped somewhere as
393 * uncached, then it must also be accessed uncached
394 * by the kernel or data corruption may occur
395 */
396 kbuf = xlate_dev_kmem_ptr((char *)p);
397
398 if (copy_to_user(buf, kbuf, sz))
399 return -EFAULT;
400 buf += sz;
401 p += sz;
402 read += sz;
403 low_count -= sz;
404 count -= sz;
405 }
406 }
407
408 if (count > 0) {
409 kbuf = (char *)__get_free_page(GFP_KERNEL);
410 if (!kbuf)
411 return -ENOMEM;
412 while (count > 0) {
413 int len = count;
414
415 if (len > PAGE_SIZE)
416 len = PAGE_SIZE;
417 len = vread(kbuf, (char *)p, len);
418 if (!len)
419 break;
420 if (copy_to_user(buf, kbuf, len)) {
421 free_page((unsigned long)kbuf);
422 return -EFAULT;
423 }
424 count -= len;
425 buf += len;
426 read += len;
427 p += len;
428 }
429 free_page((unsigned long)kbuf);
430 }
431 *ppos = p;
432 return read;
433}
434
435
436static inline ssize_t
437do_write_kmem(void *p, unsigned long realp, const char __user * buf,
438 size_t count, loff_t *ppos)
439{
440 ssize_t written, sz;
441 unsigned long copied;
442
443 written = 0;
444#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
445 /* we don't have page 0 mapped on sparc and m68k.. */
446 if (realp < PAGE_SIZE) {
447 unsigned long sz = PAGE_SIZE - realp;
448 if (sz > count)
449 sz = count;
450 /* Hmm. Do something? */
451 buf += sz;
452 p += sz;
453 realp += sz;
454 count -= sz;
455 written += sz;
456 }
457#endif
458
459 while (count > 0) {
460 char *ptr;
461 /*
462 * Handle first page in case it's not aligned
463 */
464 if (-realp & (PAGE_SIZE - 1))
465 sz = -realp & (PAGE_SIZE - 1);
466 else
467 sz = PAGE_SIZE;
468
469 sz = min_t(unsigned long, sz, count);
470
471 /*
472 * On ia64 if a page has been mapped somewhere as
473 * uncached, then it must also be accessed uncached
474 * by the kernel or data corruption may occur
475 */
476 ptr = xlate_dev_kmem_ptr(p);
477
478 copied = copy_from_user(ptr, buf, sz);
479 if (copied) {
Jan Beulichc654d602006-03-25 03:07:31 -0800480 written += sz - copied;
481 if (written)
482 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 return -EFAULT;
484 }
485 buf += sz;
486 p += sz;
487 realp += sz;
488 count -= sz;
489 written += sz;
490 }
491
492 *ppos += written;
493 return written;
494}
495
496
497/*
498 * This function writes to the *virtual* memory as seen by the kernel.
499 */
500static ssize_t write_kmem(struct file * file, const char __user * buf,
501 size_t count, loff_t *ppos)
502{
503 unsigned long p = *ppos;
504 ssize_t wrote = 0;
505 ssize_t virtr = 0;
506 ssize_t written;
507 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
508
509 if (p < (unsigned long) high_memory) {
510
511 wrote = count;
512 if (count > (unsigned long) high_memory - p)
513 wrote = (unsigned long) high_memory - p;
514
515 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
516 if (written != wrote)
517 return written;
518 wrote = written;
519 p += wrote;
520 buf += wrote;
521 count -= wrote;
522 }
523
524 if (count > 0) {
525 kbuf = (char *)__get_free_page(GFP_KERNEL);
526 if (!kbuf)
527 return wrote ? wrote : -ENOMEM;
528 while (count > 0) {
529 int len = count;
530
531 if (len > PAGE_SIZE)
532 len = PAGE_SIZE;
533 if (len) {
534 written = copy_from_user(kbuf, buf, len);
535 if (written) {
Jan Beulichc654d602006-03-25 03:07:31 -0800536 if (wrote + virtr)
537 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 free_page((unsigned long)kbuf);
Jan Beulichc654d602006-03-25 03:07:31 -0800539 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 }
541 }
542 len = vwrite(kbuf, (char *)p, len);
543 count -= len;
544 buf += len;
545 virtr += len;
546 p += len;
547 }
548 free_page((unsigned long)kbuf);
549 }
550
551 *ppos = p;
552 return virtr + wrote;
553}
554
Geoff Levand153dcc52006-09-29 02:01:23 -0700555#if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556static ssize_t read_port(struct file * file, char __user * buf,
557 size_t count, loff_t *ppos)
558{
559 unsigned long i = *ppos;
560 char __user *tmp = buf;
561
562 if (!access_ok(VERIFY_WRITE, buf, count))
563 return -EFAULT;
564 while (count-- > 0 && i < 65536) {
565 if (__put_user(inb(i),tmp) < 0)
566 return -EFAULT;
567 i++;
568 tmp++;
569 }
570 *ppos = i;
571 return tmp-buf;
572}
573
574static ssize_t write_port(struct file * file, const char __user * buf,
575 size_t count, loff_t *ppos)
576{
577 unsigned long i = *ppos;
578 const char __user * tmp = buf;
579
580 if (!access_ok(VERIFY_READ,buf,count))
581 return -EFAULT;
582 while (count-- > 0 && i < 65536) {
583 char c;
Jan Beulichc654d602006-03-25 03:07:31 -0800584 if (__get_user(c, tmp)) {
585 if (tmp > buf)
586 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 return -EFAULT;
Jan Beulichc654d602006-03-25 03:07:31 -0800588 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 outb(c,i);
590 i++;
591 tmp++;
592 }
593 *ppos = i;
594 return tmp-buf;
595}
596#endif
597
598static ssize_t read_null(struct file * file, char __user * buf,
599 size_t count, loff_t *ppos)
600{
601 return 0;
602}
603
604static ssize_t write_null(struct file * file, const char __user * buf,
605 size_t count, loff_t *ppos)
606{
607 return count;
608}
609
Jens Axboe1ebd32f2006-04-26 14:40:08 +0200610static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
611 struct splice_desc *sd)
612{
613 return sd->len;
614}
615
616static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
617 loff_t *ppos, size_t len, unsigned int flags)
618{
619 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
620}
621
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622#ifdef CONFIG_MMU
623/*
624 * For fun, we are using the MMU for this.
625 */
626static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
627{
628 struct mm_struct *mm;
629 struct vm_area_struct * vma;
630 unsigned long addr=(unsigned long)buf;
631
632 mm = current->mm;
633 /* Oops, this was forgotten before. -ben */
634 down_read(&mm->mmap_sem);
635
636 /* For private mappings, just map in zero pages. */
637 for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
638 unsigned long count;
639
640 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
641 goto out_up;
Linus Torvalds6aab3412005-11-28 14:34:23 -0800642 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 break;
644 count = vma->vm_end - addr;
645 if (count > size)
646 count = size;
647
648 zap_page_range(vma, addr, count, NULL);
Hugh Dickins5fcf7bb2006-12-10 02:18:43 -0800649 if (zeromap_page_range(vma, addr, count, PAGE_COPY))
650 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651
652 size -= count;
653 buf += count;
654 addr += count;
655 if (size == 0)
656 goto out_up;
657 }
658
659 up_read(&mm->mmap_sem);
660
661 /* The shared case is hard. Let's do the conventional zeroing. */
662 do {
663 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
664 if (unwritten)
665 return size + unwritten - PAGE_SIZE;
666 cond_resched();
667 buf += PAGE_SIZE;
668 size -= PAGE_SIZE;
669 } while (size);
670
671 return size;
672out_up:
673 up_read(&mm->mmap_sem);
674 return size;
675}
676
677static ssize_t read_zero(struct file * file, char __user * buf,
678 size_t count, loff_t *ppos)
679{
680 unsigned long left, unwritten, written = 0;
681
682 if (!count)
683 return 0;
684
685 if (!access_ok(VERIFY_WRITE, buf, count))
686 return -EFAULT;
687
688 left = count;
689
690 /* do we want to be clever? Arbitrary cut-off */
691 if (count >= PAGE_SIZE*4) {
692 unsigned long partial;
693
694 /* How much left of the page? */
695 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
696 unwritten = clear_user(buf, partial);
697 written = partial - unwritten;
698 if (unwritten)
699 goto out;
700 left -= partial;
701 buf += partial;
702 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
703 written += (left & PAGE_MASK) - unwritten;
704 if (unwritten)
705 goto out;
706 buf += left & PAGE_MASK;
707 left &= ~PAGE_MASK;
708 }
709 unwritten = clear_user(buf, left);
710 written += left - unwritten;
711out:
712 return written ? written : -EFAULT;
713}
714
715static int mmap_zero(struct file * file, struct vm_area_struct * vma)
716{
Hugh Dickins5fcf7bb2006-12-10 02:18:43 -0800717 int err;
718
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 if (vma->vm_flags & VM_SHARED)
720 return shmem_zero_setup(vma);
Hugh Dickins5fcf7bb2006-12-10 02:18:43 -0800721 err = zeromap_page_range(vma, vma->vm_start,
722 vma->vm_end - vma->vm_start, vma->vm_page_prot);
723 BUG_ON(err == -EEXIST);
724 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725}
726#else /* CONFIG_MMU */
727static ssize_t read_zero(struct file * file, char * buf,
728 size_t count, loff_t *ppos)
729{
730 size_t todo = count;
731
732 while (todo) {
733 size_t chunk = todo;
734
735 if (chunk > 4096)
736 chunk = 4096; /* Just for latency reasons */
737 if (clear_user(buf, chunk))
738 return -EFAULT;
739 buf += chunk;
740 todo -= chunk;
741 cond_resched();
742 }
743 return count;
744}
745
746static int mmap_zero(struct file * file, struct vm_area_struct * vma)
747{
748 return -ENOSYS;
749}
750#endif /* CONFIG_MMU */
751
752static ssize_t write_full(struct file * file, const char __user * buf,
753 size_t count, loff_t *ppos)
754{
755 return -ENOSPC;
756}
757
758/*
759 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
760 * can fopen() both devices with "a" now. This was previously impossible.
761 * -- SRB.
762 */
763
764static loff_t null_lseek(struct file * file, loff_t offset, int orig)
765{
766 return file->f_pos = 0;
767}
768
769/*
770 * The memory devices use the full 32/64 bits of the offset, and so we cannot
771 * check against negative addresses: they are ok. The return value is weird,
772 * though, in that case (0).
773 *
774 * also note that seeking relative to the "end of file" isn't supported:
775 * it has no meaning, so it returns -EINVAL.
776 */
777static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
778{
779 loff_t ret;
780
Josef Sipeka7113a92006-12-08 02:36:55 -0800781 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 switch (orig) {
783 case 0:
784 file->f_pos = offset;
785 ret = file->f_pos;
786 force_successful_syscall_return();
787 break;
788 case 1:
789 file->f_pos += offset;
790 ret = file->f_pos;
791 force_successful_syscall_return();
792 break;
793 default:
794 ret = -EINVAL;
795 }
Josef Sipeka7113a92006-12-08 02:36:55 -0800796 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 return ret;
798}
799
800static int open_port(struct inode * inode, struct file * filp)
801{
802 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
803}
804
805#define zero_lseek null_lseek
806#define full_lseek null_lseek
807#define write_zero write_null
808#define read_full read_zero
809#define open_mem open_port
810#define open_kmem open_mem
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700811#define open_oldmem open_mem
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812
Arjan van de Ven62322d22006-07-03 00:24:21 -0700813static const struct file_operations mem_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 .llseek = memory_lseek,
815 .read = read_mem,
816 .write = write_mem,
817 .mmap = mmap_mem,
818 .open = open_mem,
David Howells5da61852006-09-27 01:50:16 -0700819 .get_unmapped_area = get_unmapped_area_mem,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820};
821
Arjan van de Ven62322d22006-07-03 00:24:21 -0700822static const struct file_operations kmem_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823 .llseek = memory_lseek,
824 .read = read_kmem,
825 .write = write_kmem,
826 .mmap = mmap_kmem,
827 .open = open_kmem,
David Howells5da61852006-09-27 01:50:16 -0700828 .get_unmapped_area = get_unmapped_area_mem,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829};
830
Arjan van de Ven62322d22006-07-03 00:24:21 -0700831static const struct file_operations null_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 .llseek = null_lseek,
833 .read = read_null,
834 .write = write_null,
Jens Axboe1ebd32f2006-04-26 14:40:08 +0200835 .splice_write = splice_write_null,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836};
837
Geoff Levand153dcc52006-09-29 02:01:23 -0700838#if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
Arjan van de Ven62322d22006-07-03 00:24:21 -0700839static const struct file_operations port_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 .llseek = memory_lseek,
841 .read = read_port,
842 .write = write_port,
843 .open = open_port,
844};
845#endif
846
Arjan van de Ven62322d22006-07-03 00:24:21 -0700847static const struct file_operations zero_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 .llseek = zero_lseek,
849 .read = read_zero,
850 .write = write_zero,
851 .mmap = mmap_zero,
852};
853
David Howells5da61852006-09-27 01:50:16 -0700854/*
855 * capabilities for /dev/zero
856 * - permits private mappings, "copies" are taken of the source of zeros
857 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858static struct backing_dev_info zero_bdi = {
859 .capabilities = BDI_CAP_MAP_COPY,
860};
861
Arjan van de Ven62322d22006-07-03 00:24:21 -0700862static const struct file_operations full_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 .llseek = full_lseek,
864 .read = read_full,
865 .write = write_full,
866};
867
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700868#ifdef CONFIG_CRASH_DUMP
Arjan van de Ven62322d22006-07-03 00:24:21 -0700869static const struct file_operations oldmem_fops = {
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700870 .read = read_oldmem,
871 .open = open_oldmem,
872};
873#endif
874
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875static ssize_t kmsg_write(struct file * file, const char __user * buf,
876 size_t count, loff_t *ppos)
877{
878 char *tmp;
Guillaume Chazaraincd140a52006-01-08 01:02:43 -0800879 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880
881 tmp = kmalloc(count + 1, GFP_KERNEL);
882 if (tmp == NULL)
883 return -ENOMEM;
884 ret = -EFAULT;
885 if (!copy_from_user(tmp, buf, count)) {
886 tmp[count] = 0;
887 ret = printk("%s", tmp);
Guillaume Chazaraincd140a52006-01-08 01:02:43 -0800888 if (ret > count)
889 /* printk can add a prefix */
890 ret = count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 }
892 kfree(tmp);
893 return ret;
894}
895
Arjan van de Ven62322d22006-07-03 00:24:21 -0700896static const struct file_operations kmsg_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897 .write = kmsg_write,
898};
899
900static int memory_open(struct inode * inode, struct file * filp)
901{
902 switch (iminor(inode)) {
903 case 1:
904 filp->f_op = &mem_fops;
David Howells5da61852006-09-27 01:50:16 -0700905 filp->f_mapping->backing_dev_info =
906 &directly_mappable_cdev_bdi;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 break;
908 case 2:
909 filp->f_op = &kmem_fops;
David Howells5da61852006-09-27 01:50:16 -0700910 filp->f_mapping->backing_dev_info =
911 &directly_mappable_cdev_bdi;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 break;
913 case 3:
914 filp->f_op = &null_fops;
915 break;
Geoff Levand153dcc52006-09-29 02:01:23 -0700916#if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 case 4:
918 filp->f_op = &port_fops;
919 break;
920#endif
921 case 5:
922 filp->f_mapping->backing_dev_info = &zero_bdi;
923 filp->f_op = &zero_fops;
924 break;
925 case 7:
926 filp->f_op = &full_fops;
927 break;
928 case 8:
929 filp->f_op = &random_fops;
930 break;
931 case 9:
932 filp->f_op = &urandom_fops;
933 break;
934 case 11:
935 filp->f_op = &kmsg_fops;
936 break;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700937#ifdef CONFIG_CRASH_DUMP
938 case 12:
939 filp->f_op = &oldmem_fops;
940 break;
941#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 default:
943 return -ENXIO;
944 }
945 if (filp->f_op && filp->f_op->open)
946 return filp->f_op->open(inode,filp);
947 return 0;
948}
949
Arjan van de Ven62322d22006-07-03 00:24:21 -0700950static const struct file_operations memory_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 .open = memory_open, /* just a selector for the real open */
952};
953
954static const struct {
955 unsigned int minor;
956 char *name;
957 umode_t mode;
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800958 const struct file_operations *fops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959} devlist[] = { /* list of minor devices */
960 {1, "mem", S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
961 {2, "kmem", S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
962 {3, "null", S_IRUGO | S_IWUGO, &null_fops},
Geoff Levand153dcc52006-09-29 02:01:23 -0700963#if (defined(CONFIG_ISA) || defined(CONFIG_PCI)) && !defined(__mc68000__)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 {4, "port", S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
965#endif
966 {5, "zero", S_IRUGO | S_IWUGO, &zero_fops},
967 {7, "full", S_IRUGO | S_IWUGO, &full_fops},
968 {8, "random", S_IRUGO | S_IWUSR, &random_fops},
969 {9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops},
970 {11,"kmsg", S_IRUGO | S_IWUSR, &kmsg_fops},
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700971#ifdef CONFIG_CRASH_DUMP
972 {12,"oldmem", S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
973#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974};
975
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800976static struct class *mem_class;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977
978static int __init chr_dev_init(void)
979{
980 int i;
981
982 if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
983 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
984
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800985 mem_class = class_create(THIS_MODULE, "mem");
Greg Kroah-Hartman7c69ef72005-06-20 21:15:16 -0700986 for (i = 0; i < ARRAY_SIZE(devlist); i++)
Greg Kroah-Hartmanebf644c2006-07-25 17:13:31 -0700987 device_create(mem_class, NULL,
988 MKDEV(MEM_MAJOR, devlist[i].minor),
989 devlist[i].name);
990
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 return 0;
992}
993
994fs_initcall(chr_dev_init);