?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[linux-btrfs-devel.git] / arch / m32r / include / asm / uaccess.h
blob1c7047bea2002b013ab779a8c752654b9a2a9c23
1 #ifndef _ASM_M32R_UACCESS_H
2 #define _ASM_M32R_UACCESS_H
3
4 /*
5 * linux/include/asm-m32r/uaccess.h
6 *
7 * M32R version.
8 * Copyright (C) 2004, 2006 Hirokazu Takata <takata at linux-m32r.org>
9 */
10
11 /*
12 * User space memory access functions
13 */
14 #include <linux/errno.h>
15 #include <linux/thread_info.h>
16 #include <asm/page.h>
17 #include <asm/setup.h>
18
19 #define VERIFY_READ 0
20 #define VERIFY_WRITE 1
21
22 /*
23 * The fs value determines whether argument validity checking should be
24 * performed or not. If get_fs() == USER_DS, checking is performed, with
25 * get_fs() == KERNEL_DS, checking is bypassed.
26 *
27 * For historical reasons, these macros are grossly misnamed.
28 */
29
30 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
31
32 #ifdef CONFIG_MMU
33
34 #define KERNEL_DS MAKE_MM_SEG(0xFFFFFFFF)
35 #define USER_DS MAKE_MM_SEG(PAGE_OFFSET)
36 #define get_ds() (KERNEL_DS)
37 #define get_fs() (current_thread_info()->addr_limit)
38 #define set_fs(x) (current_thread_info()->addr_limit = (x))
39
40 #else /* not CONFIG_MMU */
41
42 #define KERNEL_DS MAKE_MM_SEG(0xFFFFFFFF)
43 #define USER_DS MAKE_MM_SEG(0xFFFFFFFF)
44 #define get_ds() (KERNEL_DS)
45
46 static inline mm_segment_t get_fs(void)
47 {
48 return USER_DS;
49 }
50
51 static inline void set_fs(mm_segment_t s)
52 {
53 }
54
55 #endif /* not CONFIG_MMU */
56
57 #define segment_eq(a,b) ((a).seg == (b).seg)
58
59 #define __addr_ok(addr) \
60 ((unsigned long)(addr) < (current_thread_info()->addr_limit.seg))
61
62 /*
63 * Test whether a block of memory is a valid user space address.
64 * Returns 0 if the range is valid, nonzero otherwise.
65 *
66 * This is equivalent to the following test:
67 * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
68 *
69 * This needs 33-bit arithmetic. We have a carry...
70 */
71 #define __range_ok(addr,size) ({ \
72 unsigned long flag, roksum; \
73 __chk_user_ptr(addr); \
74 asm ( \
75 " cmpu %1, %1 ; clear cbit\n" \
76 " addx %1, %3 ; set cbit if overflow\n" \
77 " subx %0, %0\n" \
78 " cmpu %4, %1\n" \
79 " subx %0, %5\n" \
80 : "=&r" (flag), "=r" (roksum) \
81 : "1" (addr), "r" ((int)(size)), \
82 "r" (current_thread_info()->addr_limit.seg), "r" (0) \
83 : "cbit" ); \
84 flag; })
85
86 /**
87 * access_ok: - Checks if a user space pointer is valid
88 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
89 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
90 * to write to a block, it is always safe to read from it.
91 * @addr: User space pointer to start of block to check
92 * @size: Size of block to check
93 *
94 * Context: User context only. This function may sleep.
95 *
96 * Checks if a pointer to a block of memory in user space is valid.
97 *
98 * Returns true (nonzero) if the memory block may be valid, false (zero)
99 * if it is definitely invalid.
100 *
101 * Note that, depending on architecture, this function probably just
102 * checks that the pointer is in the user space range - after calling
103 * this function, memory access functions may still return -EFAULT.
104 */
105 #ifdef CONFIG_MMU
106 #define access_ok(type,addr,size) (likely(__range_ok(addr,size) == 0))
107 #else
108 static inline int access_ok(int type, const void *addr, unsigned long size)
109 {
110 unsigned long val = (unsigned long)addr;
111
112 return ((val >= memory_start) && ((val + size) < memory_end));
113 }
114 #endif /* CONFIG_MMU */
115
116 /*
117 * The exception table consists of pairs of addresses: the first is the
118 * address of an instruction that is allowed to fault, and the second is
119 * the address at which the program should continue. No registers are
120 * modified, so it is entirely up to the continuation code to figure out
121 * what to do.
122 *
123 * All the routines below use bits of fixup code that are out of line
124 * with the main instruction path. This means when everything is well,
125 * we don't even have to jump over them. Further, they do not intrude
126 * on our cache or tlb entries.
127 */
128
129 struct exception_table_entry
130 {
131 unsigned long insn, fixup;
132 };
133
134 extern int fixup_exception(struct pt_regs *regs);
135
136 /*
137 * These are the main single-value transfer routines. They automatically
138 * use the right size if we just have the right pointer type.
139 *
140 * This gets kind of ugly. We want to return _two_ values in "get_user()"
141 * and yet we don't want to do any pointers, because that is too much
142 * of a performance impact. Thus we have a few rather ugly macros here,
143 * and hide all the uglyness from the user.
144 *
145 * The "__xxx" versions of the user access functions are versions that
146 * do not verify the address space, that must have been done previously
147 * with a separate "access_ok()" call (this is used when we do multiple
148 * accesses to the same area of user memory).
149 */
150
151 /* Careful: we have to cast the result to the type of the pointer for sign
152 reasons */
153 /**
154 * get_user: - Get a simple variable from user space.
155 * @x: Variable to store result.
156 * @ptr: Source address, in user space.
157 *
158 * Context: User context only. This function may sleep.
159 *
160 * This macro copies a single simple variable from user space to kernel
161 * space. It supports simple types like char and int, but not larger
162 * data types like structures or arrays.
163 *
164 * @ptr must have pointer-to-simple-variable type, and the result of
165 * dereferencing @ptr must be assignable to @x without a cast.
166 *
167 * Returns zero on success, or -EFAULT on error.
168 * On error, the variable @x is set to zero.
169 */
170 #define get_user(x,ptr) \
171 __get_user_check((x),(ptr),sizeof(*(ptr)))
172
173 /**
174 * put_user: - Write a simple value into user space.
175 * @x: Value to copy to user space.
176 * @ptr: Destination address, in user space.
177 *
178 * Context: User context only. This function may sleep.
179 *
180 * This macro copies a single simple value from kernel space to user
181 * space. It supports simple types like char and int, but not larger
182 * data types like structures or arrays.
183 *
184 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
185 * to the result of dereferencing @ptr.
186 *
187 * Returns zero on success, or -EFAULT on error.
188 */
189 #define put_user(x,ptr) \
190 __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
191
192 /**
193 * __get_user: - Get a simple variable from user space, with less checking.
194 * @x: Variable to store result.
195 * @ptr: Source address, in user space.
196 *
197 * Context: User context only. This function may sleep.
198 *
199 * This macro copies a single simple variable from user space to kernel
200 * space. It supports simple types like char and int, but not larger
201 * data types like structures or arrays.
202 *
203 * @ptr must have pointer-to-simple-variable type, and the result of
204 * dereferencing @ptr must be assignable to @x without a cast.
205 *
206 * Caller must check the pointer with access_ok() before calling this
207 * function.
208 *
209 * Returns zero on success, or -EFAULT on error.
210 * On error, the variable @x is set to zero.
211 */
212 #define __get_user(x,ptr) \
213 __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
214
215 #define __get_user_nocheck(x,ptr,size) \
216 ({ \
217 long __gu_err = 0; \
218 unsigned long __gu_val; \
219 might_sleep(); \
220 __get_user_size(__gu_val,(ptr),(size),__gu_err); \
221 (x) = (__typeof__(*(ptr)))__gu_val; \
222 __gu_err; \
223 })
224
225 #define __get_user_check(x,ptr,size) \
226 ({ \
227 long __gu_err = -EFAULT; \
228 unsigned long __gu_val = 0; \
229 const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
230 might_sleep(); \
231 if (access_ok(VERIFY_READ,__gu_addr,size)) \
232 __get_user_size(__gu_val,__gu_addr,(size),__gu_err); \
233 (x) = (__typeof__(*(ptr)))__gu_val; \
234 __gu_err; \
235 })
236
237 extern long __get_user_bad(void);
238
239 #define __get_user_size(x,ptr,size,retval) \
240 do { \
241 retval = 0; \
242 __chk_user_ptr(ptr); \
243 switch (size) { \
244 case 1: __get_user_asm(x,ptr,retval,"ub"); break; \
245 case 2: __get_user_asm(x,ptr,retval,"uh"); break; \
246 case 4: __get_user_asm(x,ptr,retval,""); break; \
247 default: (x) = __get_user_bad(); \
248 } \
249 } while (0)
250
251 #define __get_user_asm(x, addr, err, itype) \
252 __asm__ __volatile__( \
253 " .fillinsn\n" \
254 "1: ld"itype" %1,@%2\n" \
255 " .fillinsn\n" \
256 "2:\n" \
257 ".section .fixup,\"ax\"\n" \
258 " .balign 4\n" \
259 "3: ldi %0,%3\n" \
260 " seth r14,#high(2b)\n" \
261 " or3 r14,r14,#low(2b)\n" \
262 " jmp r14\n" \
263 ".previous\n" \
264 ".section __ex_table,\"a\"\n" \
265 " .balign 4\n" \
266 " .long 1b,3b\n" \
267 ".previous" \
268 : "=&r" (err), "=&r" (x) \
269 : "r" (addr), "i" (-EFAULT), "0" (err) \
270 : "r14", "memory")
271
272 /**
273 * __put_user: - Write a simple value into user space, with less checking.
274 * @x: Value to copy to user space.
275 * @ptr: Destination address, in user space.
276 *
277 * Context: User context only. This function may sleep.
278 *
279 * This macro copies a single simple value from kernel space to user
280 * space. It supports simple types like char and int, but not larger
281 * data types like structures or arrays.
282 *
283 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
284 * to the result of dereferencing @ptr.
285 *
286 * Caller must check the pointer with access_ok() before calling this
287 * function.
288 *
289 * Returns zero on success, or -EFAULT on error.
290 */
291 #define __put_user(x,ptr) \
292 __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
293
294
295 #define __put_user_nocheck(x,ptr,size) \
296 ({ \
297 long __pu_err; \
298 might_sleep(); \
299 __put_user_size((x),(ptr),(size),__pu_err); \
300 __pu_err; \
301 })
302
303
304 #define __put_user_check(x,ptr,size) \
305 ({ \
306 long __pu_err = -EFAULT; \
307 __typeof__(*(ptr)) __user *__pu_addr = (ptr); \
308 might_sleep(); \
309 if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
310 __put_user_size((x),__pu_addr,(size),__pu_err); \
311 __pu_err; \
312 })
313
314 #if defined(__LITTLE_ENDIAN__)
315 #define __put_user_u64(x, addr, err) \
316 __asm__ __volatile__( \
317 " .fillinsn\n" \
318 "1: st %L1,@%2\n" \
319 " .fillinsn\n" \
320 "2: st %H1,@(4,%2)\n" \
321 " .fillinsn\n" \
322 "3:\n" \
323 ".section .fixup,\"ax\"\n" \
324 " .balign 4\n" \
325 "4: ldi %0,%3\n" \
326 " seth r14,#high(3b)\n" \
327 " or3 r14,r14,#low(3b)\n" \
328 " jmp r14\n" \
329 ".previous\n" \
330 ".section __ex_table,\"a\"\n" \
331 " .balign 4\n" \
332 " .long 1b,4b\n" \
333 " .long 2b,4b\n" \
334 ".previous" \
335 : "=&r" (err) \
336 : "r" (x), "r" (addr), "i" (-EFAULT), "0" (err) \
337 : "r14", "memory")
338
339 #elif defined(__BIG_ENDIAN__)
340 #define __put_user_u64(x, addr, err) \
341 __asm__ __volatile__( \
342 " .fillinsn\n" \
343 "1: st %H1,@%2\n" \
344 " .fillinsn\n" \
345 "2: st %L1,@(4,%2)\n" \
346 " .fillinsn\n" \
347 "3:\n" \
348 ".section .fixup,\"ax\"\n" \
349 " .balign 4\n" \
350 "4: ldi %0,%3\n" \
351 " seth r14,#high(3b)\n" \
352 " or3 r14,r14,#low(3b)\n" \
353 " jmp r14\n" \
354 ".previous\n" \
355 ".section __ex_table,\"a\"\n" \
356 " .balign 4\n" \
357 " .long 1b,4b\n" \
358 " .long 2b,4b\n" \
359 ".previous" \
360 : "=&r" (err) \
361 : "r" (x), "r" (addr), "i" (-EFAULT), "0" (err) \
362 : "r14", "memory")
363 #else
364 #error no endian defined
365 #endif
366
367 extern void __put_user_bad(void);
368
369 #define __put_user_size(x,ptr,size,retval) \
370 do { \
371 retval = 0; \
372 __chk_user_ptr(ptr); \
373 switch (size) { \
374 case 1: __put_user_asm(x,ptr,retval,"b"); break; \
375 case 2: __put_user_asm(x,ptr,retval,"h"); break; \
376 case 4: __put_user_asm(x,ptr,retval,""); break; \
377 case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
378 default: __put_user_bad(); \
379 } \
380 } while (0)
381
382 struct __large_struct { unsigned long buf[100]; };
383 #define __m(x) (*(struct __large_struct *)(x))
384
385 /*
386 * Tell gcc we read from memory instead of writing: this is because
387 * we do not write to any memory gcc knows about, so there are no
388 * aliasing issues.
389 */
390 #define __put_user_asm(x, addr, err, itype) \
391 __asm__ __volatile__( \
392 " .fillinsn\n" \
393 "1: st"itype" %1,@%2\n" \
394 " .fillinsn\n" \
395 "2:\n" \
396 ".section .fixup,\"ax\"\n" \
397 " .balign 4\n" \
398 "3: ldi %0,%3\n" \
399 " seth r14,#high(2b)\n" \
400 " or3 r14,r14,#low(2b)\n" \
401 " jmp r14\n" \
402 ".previous\n" \
403 ".section __ex_table,\"a\"\n" \
404 " .balign 4\n" \
405 " .long 1b,3b\n" \
406 ".previous" \
407 : "=&r" (err) \
408 : "r" (x), "r" (addr), "i" (-EFAULT), "0" (err) \
409 : "r14", "memory")
410
411 /*
412 * Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
413 * we return the initial request size (1, 2 or 4), as copy_*_user should do.
414 * If a store crosses a page boundary and gets a fault, the m32r will not write
415 * anything, so this is accurate.
416 */
417
418 /*
419 * Copy To/From Userspace
420 */
421
422 /* Generic arbitrary sized copy. */
423 /* Return the number of bytes NOT copied. */
424 #define __copy_user(to,from,size) \
425 do { \
426 unsigned long __dst, __src, __c; \
427 __asm__ __volatile__ ( \
428 " mv r14, %0\n" \
429 " or r14, %1\n" \
430 " beq %0, %1, 9f\n" \
431 " beqz %2, 9f\n" \
432 " and3 r14, r14, #3\n" \
433 " bnez r14, 2f\n" \
434 " and3 %2, %2, #3\n" \
435 " beqz %3, 2f\n" \
436 " addi %0, #-4 ; word_copy \n" \
437 " .fillinsn\n" \
438 "0: ld r14, @%1+\n" \
439 " addi %3, #-1\n" \
440 " .fillinsn\n" \
441 "1: st r14, @+%0\n" \
442 " bnez %3, 0b\n" \
443 " beqz %2, 9f\n" \
444 " addi %0, #4\n" \
445 " .fillinsn\n" \
446 "2: ldb r14, @%1 ; byte_copy \n" \
447 " .fillinsn\n" \
448 "3: stb r14, @%0\n" \
449 " addi %1, #1\n" \
450 " addi %2, #-1\n" \
451 " addi %0, #1\n" \
452 " bnez %2, 2b\n" \
453 " .fillinsn\n" \
454 "9:\n" \
455 ".section .fixup,\"ax\"\n" \
456 " .balign 4\n" \
457 "5: addi %3, #1\n" \
458 " addi %1, #-4\n" \
459 " .fillinsn\n" \
460 "6: slli %3, #2\n" \
461 " add %2, %3\n" \
462 " addi %0, #4\n" \
463 " .fillinsn\n" \
464 "7: seth r14, #high(9b)\n" \
465 " or3 r14, r14, #low(9b)\n" \
466 " jmp r14\n" \
467 ".previous\n" \
468 ".section __ex_table,\"a\"\n" \
469 " .balign 4\n" \
470 " .long 0b,6b\n" \
471 " .long 1b,5b\n" \
472 " .long 2b,9b\n" \
473 " .long 3b,9b\n" \
474 ".previous\n" \
475 : "=&r" (__dst), "=&r" (__src), "=&r" (size), \
476 "=&r" (__c) \
477 : "0" (to), "1" (from), "2" (size), "3" (size / 4) \
478 : "r14", "memory"); \
479 } while (0)
480
481 #define __copy_user_zeroing(to,from,size) \
482 do { \
483 unsigned long __dst, __src, __c; \
484 __asm__ __volatile__ ( \
485 " mv r14, %0\n" \
486 " or r14, %1\n" \
487 " beq %0, %1, 9f\n" \
488 " beqz %2, 9f\n" \
489 " and3 r14, r14, #3\n" \
490 " bnez r14, 2f\n" \
491 " and3 %2, %2, #3\n" \
492 " beqz %3, 2f\n" \
493 " addi %0, #-4 ; word_copy \n" \
494 " .fillinsn\n" \
495 "0: ld r14, @%1+\n" \
496 " addi %3, #-1\n" \
497 " .fillinsn\n" \
498 "1: st r14, @+%0\n" \
499 " bnez %3, 0b\n" \
500 " beqz %2, 9f\n" \
501 " addi %0, #4\n" \
502 " .fillinsn\n" \
503 "2: ldb r14, @%1 ; byte_copy \n" \
504 " .fillinsn\n" \
505 "3: stb r14, @%0\n" \
506 " addi %1, #1\n" \
507 " addi %2, #-1\n" \
508 " addi %0, #1\n" \
509 " bnez %2, 2b\n" \
510 " .fillinsn\n" \
511 "9:\n" \
512 ".section .fixup,\"ax\"\n" \
513 " .balign 4\n" \
514 "5: addi %3, #1\n" \
515 " addi %1, #-4\n" \
516 " .fillinsn\n" \
517 "6: slli %3, #2\n" \
518 " add %2, %3\n" \
519 " addi %0, #4\n" \
520 " .fillinsn\n" \
521 "7: ldi r14, #0 ; store zero \n" \
522 " .fillinsn\n" \
523 "8: addi %2, #-1\n" \
524 " stb r14, @%0 ; ACE? \n" \
525 " addi %0, #1\n" \
526 " bnez %2, 8b\n" \
527 " seth r14, #high(9b)\n" \
528 " or3 r14, r14, #low(9b)\n" \
529 " jmp r14\n" \
530 ".previous\n" \
531 ".section __ex_table,\"a\"\n" \
532 " .balign 4\n" \
533 " .long 0b,6b\n" \
534 " .long 1b,5b\n" \
535 " .long 2b,7b\n" \
536 " .long 3b,7b\n" \
537 ".previous\n" \
538 : "=&r" (__dst), "=&r" (__src), "=&r" (size), \
539 "=&r" (__c) \
540 : "0" (to), "1" (from), "2" (size), "3" (size / 4) \
541 : "r14", "memory"); \
542 } while (0)
543
544
545 /* We let the __ versions of copy_from/to_user inline, because they're often
546 * used in fast paths and have only a small space overhead.
547 */
548 static inline unsigned long __generic_copy_from_user_nocheck(void *to,
549 const void __user *from, unsigned long n)
550 {
551 __copy_user_zeroing(to,from,n);
552 return n;
553 }
554
555 static inline unsigned long __generic_copy_to_user_nocheck(void __user *to,
556 const void *from, unsigned long n)
557 {
558 __copy_user(to,from,n);
559 return n;
560 }
561
562 unsigned long __generic_copy_to_user(void __user *, const void *, unsigned long);
563 unsigned long __generic_copy_from_user(void *, const void __user *, unsigned long);
564
565 /**
566 * __copy_to_user: - Copy a block of data into user space, with less checking.
567 * @to: Destination address, in user space.
568 * @from: Source address, in kernel space.
569 * @n: Number of bytes to copy.
570 *
571 * Context: User context only. This function may sleep.
572 *
573 * Copy data from kernel space to user space. Caller must check
574 * the specified block with access_ok() before calling this function.
575 *
576 * Returns number of bytes that could not be copied.
577 * On success, this will be zero.
578 */
579 #define __copy_to_user(to,from,n) \
580 __generic_copy_to_user_nocheck((to),(from),(n))
581
582 #define __copy_to_user_inatomic __copy_to_user
583 #define __copy_from_user_inatomic __copy_from_user
584
585 /**
586 * copy_to_user: - Copy a block of data into user space.
587 * @to: Destination address, in user space.
588 * @from: Source address, in kernel space.
589 * @n: Number of bytes to copy.
590 *
591 * Context: User context only. This function may sleep.
592 *
593 * Copy data from kernel space to user space.
594 *
595 * Returns number of bytes that could not be copied.
596 * On success, this will be zero.
597 */
598 #define copy_to_user(to,from,n) \
599 ({ \
600 might_sleep(); \
601 __generic_copy_to_user((to),(from),(n)); \
602 })
603
604 /**
605 * __copy_from_user: - Copy a block of data from user space, with less checking. * @to: Destination address, in kernel space.
606 * @from: Source address, in user space.
607 * @n: Number of bytes to copy.
608 *
609 * Context: User context only. This function may sleep.
610 *
611 * Copy data from user space to kernel space. Caller must check
612 * the specified block with access_ok() before calling this function.
613 *
614 * Returns number of bytes that could not be copied.
615 * On success, this will be zero.
616 *
617 * If some data could not be copied, this function will pad the copied
618 * data to the requested size using zero bytes.
619 */
620 #define __copy_from_user(to,from,n) \
621 __generic_copy_from_user_nocheck((to),(from),(n))
622
623 /**
624 * copy_from_user: - Copy a block of data from user space.
625 * @to: Destination address, in kernel space.
626 * @from: Source address, in user space.
627 * @n: Number of bytes to copy.
628 *
629 * Context: User context only. This function may sleep.
630 *
631 * Copy data from user space to kernel space.
632 *
633 * Returns number of bytes that could not be copied.
634 * On success, this will be zero.
635 *
636 * If some data could not be copied, this function will pad the copied
637 * data to the requested size using zero bytes.
638 */
639 #define copy_from_user(to,from,n) \
640 ({ \
641 might_sleep(); \
642 __generic_copy_from_user((to),(from),(n)); \
643 })
644
645 long __must_check strncpy_from_user(char *dst, const char __user *src,
646 long count);
647 long __must_check __strncpy_from_user(char *dst,
648 const char __user *src, long count);
649
650 /**
651 * __clear_user: - Zero a block of memory in user space, with less checking.
652 * @to: Destination address, in user space.
653 * @n: Number of bytes to zero.
654 *
655 * Zero a block of memory in user space. Caller must check
656 * the specified block with access_ok() before calling this function.
657 *
658 * Returns number of bytes that could not be cleared.
659 * On success, this will be zero.
660 */
661 unsigned long __clear_user(void __user *mem, unsigned long len);
662
663 /**
664 * clear_user: - Zero a block of memory in user space.
665 * @to: Destination address, in user space.
666 * @n: Number of bytes to zero.
667 *
668 * Zero a block of memory in user space. Caller must check
669 * the specified block with access_ok() before calling this function.
670 *
671 * Returns number of bytes that could not be cleared.
672 * On success, this will be zero.
673 */
674 unsigned long clear_user(void __user *mem, unsigned long len);
675
676 /**
677 * strlen_user: - Get the size of a string in user space.
678 * @str: The string to measure.
679 *
680 * Context: User context only. This function may sleep.
681 *
682 * Get the size of a NUL-terminated string in user space.
683 *
684 * Returns the size of the string INCLUDING the terminating NUL.
685 * On exception, returns 0.
686 *
687 * If there is a limit on the length of a valid string, you may wish to
688 * consider using strnlen_user() instead.
689 */
690 #define strlen_user(str) strnlen_user(str, ~0UL >> 1)
691 long strnlen_user(const char __user *str, long n);
692
693 #endif /* _ASM_M32R_UACCESS_H */
Linux Btrfs Development