blob: 6431f6921a67acde3c214f784904c4ebd0f62678 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/ptrace.h>
22#include <linux/device.h>
Vivek Goyal50b1fdb2005-06-25 14:58:23 -070023#include <linux/highmem.h>
24#include <linux/crash_dump.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/backing-dev.h>
Vivek Goyal315c2152005-06-25 14:58:24 -070026#include <linux/bootmem.h>
Jens Axboed6b29d72007-06-04 09:59:47 +020027#include <linux/splice.h>
Linus Torvaldsb8a3ad52006-10-13 08:42:10 -070028#include <linux/pfn.h>
Jonathan Corbet1f439642008-05-15 11:04:19 -060029#include <linux/smp_lock.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{
venkatesh.pallipadi@intel.comf0970c12008-03-18 17:00:20 -070045#if defined(CONFIG_IA64)
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 /*
47 * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
48 */
49 return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
Ralf Baechle24e9d0b962007-07-10 17:32:56 +010050#elif defined(CONFIG_MIPS)
51 {
52 extern int __uncached_access(struct file *file,
53 unsigned long addr);
54
55 return __uncached_access(file, addr);
56 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070057#else
58 /*
59 * Accessing memory above the top the kernel knows about or through a file pointer
60 * that was marked O_SYNC will be done non-cached.
61 */
62 if (file->f_flags & O_SYNC)
63 return 1;
64 return addr >= __pa(high_memory);
65#endif
66}
67
68#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
Bjorn Helgaas136939a2006-03-26 01:37:05 -080069static inline int valid_phys_addr_range(unsigned long addr, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070{
Bjorn Helgaas136939a2006-03-26 01:37:05 -080071 if (addr + count > __pa(high_memory))
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 return 0;
73
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 return 1;
75}
Bjorn Helgaas80851ef2006-01-08 01:04:13 -080076
Lennert Buytenhek06c67be2006-07-10 04:45:27 -070077static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
Bjorn Helgaas80851ef2006-01-08 01:04:13 -080078{
79 return 1;
80}
Linus Torvalds1da177e2005-04-16 15:20:36 -070081#endif
82
Ingo Molnard0926332008-07-18 00:26:59 +020083#ifdef CONFIG_STRICT_DEVMEM
Venki Pallipadie2beb3e2008-03-06 23:01:47 -080084static inline int range_is_allowed(unsigned long pfn, unsigned long size)
Arjan van de Venae531c22008-04-24 23:40:47 +020085{
Venki Pallipadie2beb3e2008-03-06 23:01:47 -080086 u64 from = ((u64)pfn) << PAGE_SHIFT;
87 u64 to = from + size;
88 u64 cursor = from;
Arjan van de Venae531c22008-04-24 23:40:47 +020089
Venki Pallipadie2beb3e2008-03-06 23:01:47 -080090 while (cursor < to) {
91 if (!devmem_is_allowed(pfn)) {
92 printk(KERN_INFO
93 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
Arjan van de Venae531c22008-04-24 23:40:47 +020094 current->comm, from, to);
95 return 0;
96 }
Venki Pallipadie2beb3e2008-03-06 23:01:47 -080097 cursor += PAGE_SIZE;
98 pfn++;
Arjan van de Venae531c22008-04-24 23:40:47 +020099 }
100 return 1;
101}
102#else
Venki Pallipadie2beb3e2008-03-06 23:01:47 -0800103static inline int range_is_allowed(unsigned long pfn, unsigned long size)
Arjan van de Venae531c22008-04-24 23:40:47 +0200104{
105 return 1;
106}
107#endif
108
venkatesh.pallipadi@intel.come045fb22008-03-18 17:00:15 -0700109void __attribute__((weak)) unxlate_dev_mem_ptr(unsigned long phys, void *addr)
110{
111}
112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113/*
114 * This funcion reads the *physical* memory. The f_pos points directly to the
115 * memory location.
116 */
117static ssize_t read_mem(struct file * file, char __user * buf,
118 size_t count, loff_t *ppos)
119{
120 unsigned long p = *ppos;
121 ssize_t read, sz;
122 char *ptr;
123
Bjorn Helgaas136939a2006-03-26 01:37:05 -0800124 if (!valid_phys_addr_range(p, count))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 return -EFAULT;
126 read = 0;
127#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
128 /* we don't have page 0 mapped on sparc and m68k.. */
129 if (p < PAGE_SIZE) {
130 sz = PAGE_SIZE - p;
131 if (sz > count)
132 sz = count;
133 if (sz > 0) {
134 if (clear_user(buf, sz))
135 return -EFAULT;
136 buf += sz;
137 p += sz;
138 count -= sz;
139 read += sz;
140 }
141 }
142#endif
143
144 while (count > 0) {
145 /*
146 * Handle first page in case it's not aligned
147 */
148 if (-p & (PAGE_SIZE - 1))
149 sz = -p & (PAGE_SIZE - 1);
150 else
151 sz = PAGE_SIZE;
152
153 sz = min_t(unsigned long, sz, count);
154
venkatesh.pallipadi@intel.come045fb22008-03-18 17:00:15 -0700155 if (!range_is_allowed(p >> PAGE_SHIFT, count))
156 return -EPERM;
157
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 /*
159 * On ia64 if a page has been mapped somewhere as
160 * uncached, then it must also be accessed uncached
161 * by the kernel or data corruption may occur
162 */
163 ptr = xlate_dev_mem_ptr(p);
venkatesh.pallipadi@intel.come045fb22008-03-18 17:00:15 -0700164 if (!ptr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 return -EFAULT;
venkatesh.pallipadi@intel.come045fb22008-03-18 17:00:15 -0700166
167 if (copy_to_user(buf, ptr, sz)) {
168 unxlate_dev_mem_ptr(p, ptr);
169 return -EFAULT;
170 }
171
172 unxlate_dev_mem_ptr(p, ptr);
173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 buf += sz;
175 p += sz;
176 count -= sz;
177 read += sz;
178 }
179
180 *ppos += read;
181 return read;
182}
183
184static ssize_t write_mem(struct file * file, const char __user * buf,
185 size_t count, loff_t *ppos)
186{
187 unsigned long p = *ppos;
188 ssize_t written, sz;
189 unsigned long copied;
190 void *ptr;
191
Bjorn Helgaas136939a2006-03-26 01:37:05 -0800192 if (!valid_phys_addr_range(p, count))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 return -EFAULT;
194
195 written = 0;
196
197#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
198 /* we don't have page 0 mapped on sparc and m68k.. */
199 if (p < PAGE_SIZE) {
200 unsigned long sz = PAGE_SIZE - p;
201 if (sz > count)
202 sz = count;
203 /* Hmm. Do something? */
204 buf += sz;
205 p += sz;
206 count -= sz;
207 written += sz;
208 }
209#endif
210
211 while (count > 0) {
212 /*
213 * Handle first page in case it's not aligned
214 */
215 if (-p & (PAGE_SIZE - 1))
216 sz = -p & (PAGE_SIZE - 1);
217 else
218 sz = PAGE_SIZE;
219
220 sz = min_t(unsigned long, sz, count);
221
venkatesh.pallipadi@intel.come045fb22008-03-18 17:00:15 -0700222 if (!range_is_allowed(p >> PAGE_SHIFT, sz))
223 return -EPERM;
224
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 /*
226 * On ia64 if a page has been mapped somewhere as
227 * uncached, then it must also be accessed uncached
228 * by the kernel or data corruption may occur
229 */
230 ptr = xlate_dev_mem_ptr(p);
venkatesh.pallipadi@intel.come045fb22008-03-18 17:00:15 -0700231 if (!ptr) {
Jan Beulichc654d602006-03-25 03:07:31 -0800232 if (written)
233 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 return -EFAULT;
235 }
venkatesh.pallipadi@intel.come045fb22008-03-18 17:00:15 -0700236
237 copied = copy_from_user(ptr, buf, sz);
238 if (copied) {
239 written += sz - copied;
240 unxlate_dev_mem_ptr(p, ptr);
241 if (written)
242 break;
243 return -EFAULT;
244 }
245
246 unxlate_dev_mem_ptr(p, ptr);
247
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 buf += sz;
249 p += sz;
250 count -= sz;
251 written += sz;
252 }
253
254 *ppos += written;
255 return written;
256}
257
venkatesh.pallipadi@intel.comf0970c12008-03-18 17:00:20 -0700258int __attribute__((weak)) phys_mem_access_prot_allowed(struct file *file,
259 unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
260{
261 return 1;
262}
263
Bjorn Helgaas44ac8412006-01-08 01:04:10 -0800264#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
265static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
266 unsigned long size, pgprot_t vma_prot)
267{
268#ifdef pgprot_noncached
269 unsigned long offset = pfn << PAGE_SHIFT;
270
271 if (uncached_access(file, offset))
272 return pgprot_noncached(vma_prot);
273#endif
274 return vma_prot;
275}
276#endif
277
David Howells5da61852006-09-27 01:50:16 -0700278#ifndef CONFIG_MMU
279static unsigned long get_unmapped_area_mem(struct file *file,
280 unsigned long addr,
281 unsigned long len,
282 unsigned long pgoff,
283 unsigned long flags)
284{
285 if (!valid_mmap_phys_addr_range(pgoff, len))
286 return (unsigned long) -EINVAL;
Benjamin Herrenschmidt8a932582007-04-16 22:53:16 -0700287 return pgoff << PAGE_SHIFT;
David Howells5da61852006-09-27 01:50:16 -0700288}
289
290/* can't do an in-place private mapping if there's no MMU */
291static inline int private_mapping_ok(struct vm_area_struct *vma)
292{
293 return vma->vm_flags & VM_MAYSHARE;
294}
295#else
296#define get_unmapped_area_mem NULL
297
298static inline int private_mapping_ok(struct vm_area_struct *vma)
299{
300 return 1;
301}
302#endif
303
venkatesh.pallipadi@intel.come7f260a2008-03-18 17:00:21 -0700304void __attribute__((weak))
305map_devmem(unsigned long pfn, unsigned long len, pgprot_t prot)
306{
307 /* nothing. architectures can override. */
308}
309
310void __attribute__((weak))
311unmap_devmem(unsigned long pfn, unsigned long len, pgprot_t prot)
312{
313 /* nothing. architectures can override. */
314}
315
316static void mmap_mem_open(struct vm_area_struct *vma)
317{
318 map_devmem(vma->vm_pgoff, vma->vm_end - vma->vm_start,
319 vma->vm_page_prot);
320}
321
322static void mmap_mem_close(struct vm_area_struct *vma)
323{
324 unmap_devmem(vma->vm_pgoff, vma->vm_end - vma->vm_start,
325 vma->vm_page_prot);
326}
327
328static struct vm_operations_struct mmap_mem_ops = {
329 .open = mmap_mem_open,
Rik van Riel7ae8ed52008-07-23 21:27:07 -0700330 .close = mmap_mem_close,
331#ifdef CONFIG_HAVE_IOREMAP_PROT
332 .access = generic_access_phys
333#endif
venkatesh.pallipadi@intel.come7f260a2008-03-18 17:00:21 -0700334};
335
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336static int mmap_mem(struct file * file, struct vm_area_struct * vma)
337{
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800338 size_t size = vma->vm_end - vma->vm_start;
339
Lennert Buytenhek06c67be2006-07-10 04:45:27 -0700340 if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800341 return -EINVAL;
342
David Howells5da61852006-09-27 01:50:16 -0700343 if (!private_mapping_ok(vma))
344 return -ENOSYS;
345
Venki Pallipadie2beb3e2008-03-06 23:01:47 -0800346 if (!range_is_allowed(vma->vm_pgoff, size))
347 return -EPERM;
348
venkatesh.pallipadi@intel.comf0970c12008-03-18 17:00:20 -0700349 if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
350 &vma->vm_page_prot))
351 return -EINVAL;
352
Roland Dreier8b150472005-10-28 17:46:18 -0700353 vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800354 size,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 vma->vm_page_prot);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
venkatesh.pallipadi@intel.come7f260a2008-03-18 17:00:21 -0700357 vma->vm_ops = &mmap_mem_ops;
358
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
360 if (remap_pfn_range(vma,
361 vma->vm_start,
362 vma->vm_pgoff,
Bjorn Helgaas80851ef2006-01-08 01:04:13 -0800363 size,
venkatesh.pallipadi@intel.come7f260a2008-03-18 17:00:21 -0700364 vma->vm_page_prot)) {
365 unmap_devmem(vma->vm_pgoff, size, vma->vm_page_prot);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 return -EAGAIN;
venkatesh.pallipadi@intel.come7f260a2008-03-18 17:00:21 -0700367 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 return 0;
369}
370
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700371#ifdef CONFIG_DEVKMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
373{
Linus Torvalds4bb82552005-08-13 14:22:59 -0700374 unsigned long pfn;
375
Linus Torvalds6d3154c2007-01-22 08:53:24 -0800376 /* Turn a kernel-virtual address into a physical page frame */
377 pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
Linus Torvalds4bb82552005-08-13 14:22:59 -0700378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 /*
380 * RED-PEN: on some architectures there is more mapped memory
381 * than available in mem_map which pfn_valid checks
382 * for. Perhaps should add a new macro here.
383 *
384 * RED-PEN: vmalloc is not supported right now.
385 */
Linus Torvalds4bb82552005-08-13 14:22:59 -0700386 if (!pfn_valid(pfn))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 return -EIO;
Linus Torvalds4bb82552005-08-13 14:22:59 -0700388
389 vma->vm_pgoff = pfn;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 return mmap_mem(file, vma);
391}
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700392#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700394#ifdef CONFIG_CRASH_DUMP
395/*
396 * Read memory corresponding to the old kernel.
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700397 */
Vivek Goyal315c2152005-06-25 14:58:24 -0700398static ssize_t read_oldmem(struct file *file, char __user *buf,
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700399 size_t count, loff_t *ppos)
400{
Vivek Goyal315c2152005-06-25 14:58:24 -0700401 unsigned long pfn, offset;
402 size_t read = 0, csize;
403 int rc = 0;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700404
Maneesh Soni72414d32005-06-25 14:58:28 -0700405 while (count) {
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700406 pfn = *ppos / PAGE_SIZE;
Vivek Goyal315c2152005-06-25 14:58:24 -0700407 if (pfn > saved_max_pfn)
408 return read;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700409
Vivek Goyal315c2152005-06-25 14:58:24 -0700410 offset = (unsigned long)(*ppos % PAGE_SIZE);
411 if (count > PAGE_SIZE - offset)
412 csize = PAGE_SIZE - offset;
413 else
414 csize = count;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700415
Vivek Goyal315c2152005-06-25 14:58:24 -0700416 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
417 if (rc < 0)
418 return rc;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700419 buf += csize;
420 *ppos += csize;
421 read += csize;
422 count -= csize;
423 }
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700424 return read;
425}
426#endif
427
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428extern long vread(char *buf, char *addr, unsigned long count);
429extern long vwrite(char *buf, char *addr, unsigned long count);
430
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700431#ifdef CONFIG_DEVKMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432/*
433 * This function reads the *virtual* memory as seen by the kernel.
434 */
435static ssize_t read_kmem(struct file *file, char __user *buf,
436 size_t count, loff_t *ppos)
437{
438 unsigned long p = *ppos;
439 ssize_t low_count, read, sz;
440 char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
441
442 read = 0;
443 if (p < (unsigned long) high_memory) {
444 low_count = count;
445 if (count > (unsigned long) high_memory - p)
446 low_count = (unsigned long) high_memory - p;
447
448#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
449 /* we don't have page 0 mapped on sparc and m68k.. */
450 if (p < PAGE_SIZE && low_count > 0) {
451 size_t tmp = PAGE_SIZE - p;
452 if (tmp > low_count) tmp = low_count;
453 if (clear_user(buf, tmp))
454 return -EFAULT;
455 buf += tmp;
456 p += tmp;
457 read += tmp;
458 low_count -= tmp;
459 count -= tmp;
460 }
461#endif
462 while (low_count > 0) {
463 /*
464 * Handle first page in case it's not aligned
465 */
466 if (-p & (PAGE_SIZE - 1))
467 sz = -p & (PAGE_SIZE - 1);
468 else
469 sz = PAGE_SIZE;
470
471 sz = min_t(unsigned long, sz, low_count);
472
473 /*
474 * On ia64 if a page has been mapped somewhere as
475 * uncached, then it must also be accessed uncached
476 * by the kernel or data corruption may occur
477 */
478 kbuf = xlate_dev_kmem_ptr((char *)p);
479
480 if (copy_to_user(buf, kbuf, sz))
481 return -EFAULT;
482 buf += sz;
483 p += sz;
484 read += sz;
485 low_count -= sz;
486 count -= sz;
487 }
488 }
489
490 if (count > 0) {
491 kbuf = (char *)__get_free_page(GFP_KERNEL);
492 if (!kbuf)
493 return -ENOMEM;
494 while (count > 0) {
495 int len = count;
496
497 if (len > PAGE_SIZE)
498 len = PAGE_SIZE;
499 len = vread(kbuf, (char *)p, len);
500 if (!len)
501 break;
502 if (copy_to_user(buf, kbuf, len)) {
503 free_page((unsigned long)kbuf);
504 return -EFAULT;
505 }
506 count -= len;
507 buf += len;
508 read += len;
509 p += len;
510 }
511 free_page((unsigned long)kbuf);
512 }
513 *ppos = p;
514 return read;
515}
516
517
518static inline ssize_t
519do_write_kmem(void *p, unsigned long realp, const char __user * buf,
520 size_t count, loff_t *ppos)
521{
522 ssize_t written, sz;
523 unsigned long copied;
524
525 written = 0;
526#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
527 /* we don't have page 0 mapped on sparc and m68k.. */
528 if (realp < PAGE_SIZE) {
529 unsigned long sz = PAGE_SIZE - realp;
530 if (sz > count)
531 sz = count;
532 /* Hmm. Do something? */
533 buf += sz;
534 p += sz;
535 realp += sz;
536 count -= sz;
537 written += sz;
538 }
539#endif
540
541 while (count > 0) {
542 char *ptr;
543 /*
544 * Handle first page in case it's not aligned
545 */
546 if (-realp & (PAGE_SIZE - 1))
547 sz = -realp & (PAGE_SIZE - 1);
548 else
549 sz = PAGE_SIZE;
550
551 sz = min_t(unsigned long, sz, count);
552
553 /*
554 * On ia64 if a page has been mapped somewhere as
555 * uncached, then it must also be accessed uncached
556 * by the kernel or data corruption may occur
557 */
558 ptr = xlate_dev_kmem_ptr(p);
559
560 copied = copy_from_user(ptr, buf, sz);
561 if (copied) {
Jan Beulichc654d602006-03-25 03:07:31 -0800562 written += sz - copied;
563 if (written)
564 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 return -EFAULT;
566 }
567 buf += sz;
568 p += sz;
569 realp += sz;
570 count -= sz;
571 written += sz;
572 }
573
574 *ppos += written;
575 return written;
576}
577
578
579/*
580 * This function writes to the *virtual* memory as seen by the kernel.
581 */
582static ssize_t write_kmem(struct file * file, const char __user * buf,
583 size_t count, loff_t *ppos)
584{
585 unsigned long p = *ppos;
586 ssize_t wrote = 0;
587 ssize_t virtr = 0;
588 ssize_t written;
589 char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
590
591 if (p < (unsigned long) high_memory) {
592
593 wrote = count;
594 if (count > (unsigned long) high_memory - p)
595 wrote = (unsigned long) high_memory - p;
596
597 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
598 if (written != wrote)
599 return written;
600 wrote = written;
601 p += wrote;
602 buf += wrote;
603 count -= wrote;
604 }
605
606 if (count > 0) {
607 kbuf = (char *)__get_free_page(GFP_KERNEL);
608 if (!kbuf)
609 return wrote ? wrote : -ENOMEM;
610 while (count > 0) {
611 int len = count;
612
613 if (len > PAGE_SIZE)
614 len = PAGE_SIZE;
615 if (len) {
616 written = copy_from_user(kbuf, buf, len);
617 if (written) {
Jan Beulichc654d602006-03-25 03:07:31 -0800618 if (wrote + virtr)
619 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 free_page((unsigned long)kbuf);
Jan Beulichc654d602006-03-25 03:07:31 -0800621 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 }
623 }
624 len = vwrite(kbuf, (char *)p, len);
625 count -= len;
626 buf += len;
627 virtr += len;
628 p += len;
629 }
630 free_page((unsigned long)kbuf);
631 }
632
633 *ppos = p;
634 return virtr + wrote;
635}
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700636#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
Russell King4f911d62007-05-08 00:28:17 -0700638#ifdef CONFIG_DEVPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639static ssize_t read_port(struct file * file, char __user * buf,
640 size_t count, loff_t *ppos)
641{
642 unsigned long i = *ppos;
643 char __user *tmp = buf;
644
645 if (!access_ok(VERIFY_WRITE, buf, count))
646 return -EFAULT;
647 while (count-- > 0 && i < 65536) {
648 if (__put_user(inb(i),tmp) < 0)
649 return -EFAULT;
650 i++;
651 tmp++;
652 }
653 *ppos = i;
654 return tmp-buf;
655}
656
657static ssize_t write_port(struct file * file, const char __user * buf,
658 size_t count, loff_t *ppos)
659{
660 unsigned long i = *ppos;
661 const char __user * tmp = buf;
662
663 if (!access_ok(VERIFY_READ,buf,count))
664 return -EFAULT;
665 while (count-- > 0 && i < 65536) {
666 char c;
Jan Beulichc654d602006-03-25 03:07:31 -0800667 if (__get_user(c, tmp)) {
668 if (tmp > buf)
669 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 return -EFAULT;
Jan Beulichc654d602006-03-25 03:07:31 -0800671 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 outb(c,i);
673 i++;
674 tmp++;
675 }
676 *ppos = i;
677 return tmp-buf;
678}
679#endif
680
681static ssize_t read_null(struct file * file, char __user * buf,
682 size_t count, loff_t *ppos)
683{
684 return 0;
685}
686
687static ssize_t write_null(struct file * file, const char __user * buf,
688 size_t count, loff_t *ppos)
689{
690 return count;
691}
692
Jens Axboe1ebd32f2006-04-26 14:40:08 +0200693static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
694 struct splice_desc *sd)
695{
696 return sd->len;
697}
698
699static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
700 loff_t *ppos, size_t len, unsigned int flags)
701{
702 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
703}
704
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705static ssize_t read_zero(struct file * file, char __user * buf,
706 size_t count, loff_t *ppos)
707{
Nick Piggin557ed1f2007-10-16 01:24:40 -0700708 size_t written;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709
710 if (!count)
711 return 0;
712
713 if (!access_ok(VERIFY_WRITE, buf, count))
714 return -EFAULT;
715
Nick Piggin557ed1f2007-10-16 01:24:40 -0700716 written = 0;
717 while (count) {
718 unsigned long unwritten;
719 size_t chunk = count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720
Nick Piggin557ed1f2007-10-16 01:24:40 -0700721 if (chunk > PAGE_SIZE)
722 chunk = PAGE_SIZE; /* Just for latency reasons */
723 unwritten = clear_user(buf, chunk);
724 written += chunk - unwritten;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 if (unwritten)
Nick Piggin557ed1f2007-10-16 01:24:40 -0700726 break;
727 buf += chunk;
728 count -= chunk;
729 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 return written ? written : -EFAULT;
732}
733
734static int mmap_zero(struct file * file, struct vm_area_struct * vma)
735{
Nick Piggin557ed1f2007-10-16 01:24:40 -0700736#ifndef CONFIG_MMU
737 return -ENOSYS;
738#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 if (vma->vm_flags & VM_SHARED)
740 return shmem_zero_setup(vma);
Nick Piggin557ed1f2007-10-16 01:24:40 -0700741 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743
744static ssize_t write_full(struct file * file, const char __user * buf,
745 size_t count, loff_t *ppos)
746{
747 return -ENOSPC;
748}
749
750/*
751 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
752 * can fopen() both devices with "a" now. This was previously impossible.
753 * -- SRB.
754 */
755
756static loff_t null_lseek(struct file * file, loff_t offset, int orig)
757{
758 return file->f_pos = 0;
759}
760
761/*
762 * The memory devices use the full 32/64 bits of the offset, and so we cannot
763 * check against negative addresses: they are ok. The return value is weird,
764 * though, in that case (0).
765 *
766 * also note that seeking relative to the "end of file" isn't supported:
767 * it has no meaning, so it returns -EINVAL.
768 */
769static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
770{
771 loff_t ret;
772
Josef Sipeka7113a92006-12-08 02:36:55 -0800773 mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 switch (orig) {
775 case 0:
776 file->f_pos = offset;
777 ret = file->f_pos;
778 force_successful_syscall_return();
779 break;
780 case 1:
781 file->f_pos += offset;
782 ret = file->f_pos;
783 force_successful_syscall_return();
784 break;
785 default:
786 ret = -EINVAL;
787 }
Josef Sipeka7113a92006-12-08 02:36:55 -0800788 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 return ret;
790}
791
792static int open_port(struct inode * inode, struct file * filp)
793{
794 return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
795}
796
797#define zero_lseek null_lseek
798#define full_lseek null_lseek
799#define write_zero write_null
800#define read_full read_zero
801#define open_mem open_port
802#define open_kmem open_mem
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700803#define open_oldmem open_mem
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804
Arjan van de Ven62322d22006-07-03 00:24:21 -0700805static const struct file_operations mem_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 .llseek = memory_lseek,
807 .read = read_mem,
808 .write = write_mem,
809 .mmap = mmap_mem,
810 .open = open_mem,
David Howells5da61852006-09-27 01:50:16 -0700811 .get_unmapped_area = get_unmapped_area_mem,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812};
813
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700814#ifdef CONFIG_DEVKMEM
Arjan van de Ven62322d22006-07-03 00:24:21 -0700815static const struct file_operations kmem_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 .llseek = memory_lseek,
817 .read = read_kmem,
818 .write = write_kmem,
819 .mmap = mmap_kmem,
820 .open = open_kmem,
David Howells5da61852006-09-27 01:50:16 -0700821 .get_unmapped_area = get_unmapped_area_mem,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822};
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700823#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824
Arjan van de Ven62322d22006-07-03 00:24:21 -0700825static const struct file_operations null_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 .llseek = null_lseek,
827 .read = read_null,
828 .write = write_null,
Jens Axboe1ebd32f2006-04-26 14:40:08 +0200829 .splice_write = splice_write_null,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830};
831
Russell King4f911d62007-05-08 00:28:17 -0700832#ifdef CONFIG_DEVPORT
Arjan van de Ven62322d22006-07-03 00:24:21 -0700833static const struct file_operations port_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834 .llseek = memory_lseek,
835 .read = read_port,
836 .write = write_port,
837 .open = open_port,
838};
839#endif
840
Arjan van de Ven62322d22006-07-03 00:24:21 -0700841static const struct file_operations zero_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 .llseek = zero_lseek,
843 .read = read_zero,
844 .write = write_zero,
845 .mmap = mmap_zero,
846};
847
David Howells5da61852006-09-27 01:50:16 -0700848/*
849 * capabilities for /dev/zero
850 * - permits private mappings, "copies" are taken of the source of zeros
851 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852static struct backing_dev_info zero_bdi = {
853 .capabilities = BDI_CAP_MAP_COPY,
854};
855
Arjan van de Ven62322d22006-07-03 00:24:21 -0700856static const struct file_operations full_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 .llseek = full_lseek,
858 .read = read_full,
859 .write = write_full,
860};
861
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700862#ifdef CONFIG_CRASH_DUMP
Arjan van de Ven62322d22006-07-03 00:24:21 -0700863static const struct file_operations oldmem_fops = {
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700864 .read = read_oldmem,
865 .open = open_oldmem,
866};
867#endif
868
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869static ssize_t kmsg_write(struct file * file, const char __user * buf,
870 size_t count, loff_t *ppos)
871{
872 char *tmp;
Guillaume Chazaraincd140a52006-01-08 01:02:43 -0800873 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874
875 tmp = kmalloc(count + 1, GFP_KERNEL);
876 if (tmp == NULL)
877 return -ENOMEM;
878 ret = -EFAULT;
879 if (!copy_from_user(tmp, buf, count)) {
880 tmp[count] = 0;
881 ret = printk("%s", tmp);
Guillaume Chazaraincd140a52006-01-08 01:02:43 -0800882 if (ret > count)
883 /* printk can add a prefix */
884 ret = count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 }
886 kfree(tmp);
887 return ret;
888}
889
Arjan van de Ven62322d22006-07-03 00:24:21 -0700890static const struct file_operations kmsg_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 .write = kmsg_write,
892};
893
894static int memory_open(struct inode * inode, struct file * filp)
895{
Jonathan Corbet1f439642008-05-15 11:04:19 -0600896 int ret = 0;
897
898 lock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 switch (iminor(inode)) {
900 case 1:
901 filp->f_op = &mem_fops;
David Howells5da61852006-09-27 01:50:16 -0700902 filp->f_mapping->backing_dev_info =
903 &directly_mappable_cdev_bdi;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 break;
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700905#ifdef CONFIG_DEVKMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 case 2:
907 filp->f_op = &kmem_fops;
David Howells5da61852006-09-27 01:50:16 -0700908 filp->f_mapping->backing_dev_info =
909 &directly_mappable_cdev_bdi;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 break;
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700911#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 case 3:
913 filp->f_op = &null_fops;
914 break;
Russell King4f911d62007-05-08 00:28:17 -0700915#ifdef CONFIG_DEVPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 case 4:
917 filp->f_op = &port_fops;
918 break;
919#endif
920 case 5:
921 filp->f_mapping->backing_dev_info = &zero_bdi;
922 filp->f_op = &zero_fops;
923 break;
924 case 7:
925 filp->f_op = &full_fops;
926 break;
927 case 8:
928 filp->f_op = &random_fops;
929 break;
930 case 9:
931 filp->f_op = &urandom_fops;
932 break;
933 case 11:
934 filp->f_op = &kmsg_fops;
935 break;
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700936#ifdef CONFIG_CRASH_DUMP
937 case 12:
938 filp->f_op = &oldmem_fops;
939 break;
940#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941 default:
Jonathan Corbet1f439642008-05-15 11:04:19 -0600942 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700943 return -ENXIO;
944 }
945 if (filp->f_op && filp->f_op->open)
Jonathan Corbet1f439642008-05-15 11:04:19 -0600946 ret = filp->f_op->open(inode,filp);
947 unlock_kernel();
948 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949}
950
Arjan van de Ven62322d22006-07-03 00:24:21 -0700951static const struct file_operations memory_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 .open = memory_open, /* just a selector for the real open */
953};
954
955static const struct {
956 unsigned int minor;
957 char *name;
958 umode_t mode;
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800959 const struct file_operations *fops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960} devlist[] = { /* list of minor devices */
961 {1, "mem", S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700962#ifdef CONFIG_DEVKMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 {2, "kmem", S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
Arjan van de Venb781ecb2008-04-29 00:58:34 -0700964#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 {3, "null", S_IRUGO | S_IWUGO, &null_fops},
Russell King4f911d62007-05-08 00:28:17 -0700966#ifdef CONFIG_DEVPORT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 {4, "port", S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
968#endif
969 {5, "zero", S_IRUGO | S_IWUGO, &zero_fops},
970 {7, "full", S_IRUGO | S_IWUGO, &full_fops},
971 {8, "random", S_IRUGO | S_IWUSR, &random_fops},
972 {9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops},
973 {11,"kmsg", S_IRUGO | S_IWUSR, &kmsg_fops},
Vivek Goyal50b1fdb2005-06-25 14:58:23 -0700974#ifdef CONFIG_CRASH_DUMP
975 {12,"oldmem", S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
976#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977};
978
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800979static struct class *mem_class;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980
981static int __init chr_dev_init(void)
982{
983 int i;
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700984 int err;
985
986 err = bdi_init(&zero_bdi);
987 if (err)
988 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989
990 if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
991 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
992
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800993 mem_class = class_create(THIS_MODULE, "mem");
Greg Kroah-Hartman7c69ef72005-06-20 21:15:16 -0700994 for (i = 0; i < ARRAY_SIZE(devlist); i++)
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700995 device_create(mem_class, NULL,
996 MKDEV(MEM_MAJOR, devlist[i].minor), NULL,
997 devlist[i].name);
Greg Kroah-Hartmanebf644c2006-07-25 17:13:31 -0700998
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 return 0;
1000}
1001
1002fs_initcall(chr_dev_init);