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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __i386_UACCESS_H
2#define __i386_UACCESS_H
3
4/*
5 * User space memory access functions
6 */
7#include <linux/config.h>
8#include <linux/errno.h>
9#include <linux/thread_info.h>
10#include <linux/prefetch.h>
11#include <linux/string.h>
12#include <asm/page.h>
13
14#define VERIFY_READ 0
15#define VERIFY_WRITE 1
16
17/*
18 * The fs value determines whether argument validity checking should be
19 * performed or not. If get_fs() == USER_DS, checking is performed, with
20 * get_fs() == KERNEL_DS, checking is bypassed.
21 *
22 * For historical reasons, these macros are grossly misnamed.
23 */
24
25#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
26
27
28#define KERNEL_DS MAKE_MM_SEG(0xFFFFFFFFUL)
29#define USER_DS MAKE_MM_SEG(PAGE_OFFSET)
30
31#define get_ds() (KERNEL_DS)
32#define get_fs() (current_thread_info()->addr_limit)
33#define set_fs(x) (current_thread_info()->addr_limit = (x))
34
35#define segment_eq(a,b) ((a).seg == (b).seg)
36
37/*
38 * movsl can be slow when source and dest are not both 8-byte aligned
39 */
40#ifdef CONFIG_X86_INTEL_USERCOPY
41extern struct movsl_mask {
42 int mask;
43} ____cacheline_aligned_in_smp movsl_mask;
44#endif
45
46#define __addr_ok(addr) ((unsigned long __force)(addr) < (current_thread_info()->addr_limit.seg))
47
48/*
49 * Test whether a block of memory is a valid user space address.
50 * Returns 0 if the range is valid, nonzero otherwise.
51 *
52 * This is equivalent to the following test:
53 * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
54 *
55 * This needs 33-bit arithmetic. We have a carry...
56 */
57#define __range_ok(addr,size) ({ \
58 unsigned long flag,sum; \
59 __chk_user_ptr(addr); \
60 asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
61 :"=&r" (flag), "=r" (sum) \
62 :"1" (addr),"g" ((int)(size)),"g" (current_thread_info()->addr_limit.seg)); \
63 flag; })
64
65/**
66 * access_ok: - Checks if a user space pointer is valid
67 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that
68 * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
69 * to write to a block, it is always safe to read from it.
70 * @addr: User space pointer to start of block to check
71 * @size: Size of block to check
72 *
73 * Context: User context only. This function may sleep.
74 *
75 * Checks if a pointer to a block of memory in user space is valid.
76 *
77 * Returns true (nonzero) if the memory block may be valid, false (zero)
78 * if it is definitely invalid.
79 *
80 * Note that, depending on architecture, this function probably just
81 * checks that the pointer is in the user space range - after calling
82 * this function, memory access functions may still return -EFAULT.
83 */
84#define access_ok(type,addr,size) (likely(__range_ok(addr,size) == 0))
85
86/**
87 * verify_area: - Obsolete/deprecated and will go away soon,
88 * use access_ok() instead.
89 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE
90 * @addr: User space pointer to start of block to check
91 * @size: Size of block to check
92 *
93 * Context: User context only. This function may sleep.
94 *
95 * This function has been replaced by access_ok().
96 *
97 * Checks if a pointer to a block of memory in user space is valid.
98 *
99 * Returns zero if the memory block may be valid, -EFAULT
100 * if it is definitely invalid.
101 *
102 * See access_ok() for more details.
103 */
104static inline int __deprecated verify_area(int type, const void __user * addr, unsigned long size)
105{
106 return access_ok(type,addr,size) ? 0 : -EFAULT;
107}
108
109
110/*
111 * The exception table consists of pairs of addresses: the first is the
112 * address of an instruction that is allowed to fault, and the second is
113 * the address at which the program should continue. No registers are
114 * modified, so it is entirely up to the continuation code to figure out
115 * what to do.
116 *
117 * All the routines below use bits of fixup code that are out of line
118 * with the main instruction path. This means when everything is well,
119 * we don't even have to jump over them. Further, they do not intrude
120 * on our cache or tlb entries.
121 */
122
123struct exception_table_entry
124{
125 unsigned long insn, fixup;
126};
127
128extern int fixup_exception(struct pt_regs *regs);
129
130/*
131 * These are the main single-value transfer routines. They automatically
132 * use the right size if we just have the right pointer type.
133 *
134 * This gets kind of ugly. We want to return _two_ values in "get_user()"
135 * and yet we don't want to do any pointers, because that is too much
136 * of a performance impact. Thus we have a few rather ugly macros here,
137 * and hide all the ugliness from the user.
138 *
139 * The "__xxx" versions of the user access functions are versions that
140 * do not verify the address space, that must have been done previously
141 * with a separate "access_ok()" call (this is used when we do multiple
142 * accesses to the same area of user memory).
143 */
144
145extern void __get_user_1(void);
146extern void __get_user_2(void);
147extern void __get_user_4(void);
148
149#define __get_user_x(size,ret,x,ptr) \
150 __asm__ __volatile__("call __get_user_" #size \
151 :"=a" (ret),"=d" (x) \
152 :"0" (ptr))
153
154
155/* Careful: we have to cast the result to the type of the pointer for sign reasons */
156/**
157 * get_user: - Get a simple variable from user space.
158 * @x: Variable to store result.
159 * @ptr: Source address, in user space.
160 *
161 * Context: User context only. This function may sleep.
162 *
163 * This macro copies a single simple variable from user space to kernel
164 * space. It supports simple types like char and int, but not larger
165 * data types like structures or arrays.
166 *
167 * @ptr must have pointer-to-simple-variable type, and the result of
168 * dereferencing @ptr must be assignable to @x without a cast.
169 *
170 * Returns zero on success, or -EFAULT on error.
171 * On error, the variable @x is set to zero.
172 */
173#define get_user(x,ptr) \
174({ int __ret_gu; \
175 unsigned long __val_gu; \
176 __chk_user_ptr(ptr); \
177 switch(sizeof (*(ptr))) { \
178 case 1: __get_user_x(1,__ret_gu,__val_gu,ptr); break; \
179 case 2: __get_user_x(2,__ret_gu,__val_gu,ptr); break; \
180 case 4: __get_user_x(4,__ret_gu,__val_gu,ptr); break; \
181 default: __get_user_x(X,__ret_gu,__val_gu,ptr); break; \
182 } \
183 (x) = (__typeof__(*(ptr)))__val_gu; \
184 __ret_gu; \
185})
186
187extern void __put_user_bad(void);
188
189/*
190 * Strange magic calling convention: pointer in %ecx,
191 * value in %eax(:%edx), return value in %eax, no clobbers.
192 */
193extern void __put_user_1(void);
194extern void __put_user_2(void);
195extern void __put_user_4(void);
196extern void __put_user_8(void);
197
198#define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
199#define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
200#define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
201#define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu):"A" ((typeof(*(ptr)))(x)), "c" (ptr))
202#define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a" (__ret_pu):"c" (ptr))
203
204/**
205 * put_user: - Write a simple value into user space.
206 * @x: Value to copy to user space.
207 * @ptr: Destination address, in user space.
208 *
209 * Context: User context only. This function may sleep.
210 *
211 * This macro copies a single simple value from kernel space to user
212 * space. It supports simple types like char and int, but not larger
213 * data types like structures or arrays.
214 *
215 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
216 * to the result of dereferencing @ptr.
217 *
218 * Returns zero on success, or -EFAULT on error.
219 */
220#ifdef CONFIG_X86_WP_WORKS_OK
221
222#define put_user(x,ptr) \
223({ int __ret_pu; \
224 __chk_user_ptr(ptr); \
225 switch(sizeof(*(ptr))) { \
226 case 1: __put_user_1(x, ptr); break; \
227 case 2: __put_user_2(x, ptr); break; \
228 case 4: __put_user_4(x, ptr); break; \
229 case 8: __put_user_8(x, ptr); break; \
230 default:__put_user_X(x, ptr); break; \
231 } \
232 __ret_pu; \
233})
234
235#else
236#define put_user(x,ptr) \
237({ \
238 int __ret_pu; \
239 __typeof__(*(ptr)) __pus_tmp = x; \
240 __ret_pu=0; \
241 if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, \
242 sizeof(*(ptr))) != 0)) \
243 __ret_pu=-EFAULT; \
244 __ret_pu; \
245 })
246
247
248#endif
249
250/**
251 * __get_user: - Get a simple variable from user space, with less checking.
252 * @x: Variable to store result.
253 * @ptr: Source address, in user space.
254 *
255 * Context: User context only. This function may sleep.
256 *
257 * This macro copies a single simple variable from user space to kernel
258 * space. It supports simple types like char and int, but not larger
259 * data types like structures or arrays.
260 *
261 * @ptr must have pointer-to-simple-variable type, and the result of
262 * dereferencing @ptr must be assignable to @x without a cast.
263 *
264 * Caller must check the pointer with access_ok() before calling this
265 * function.
266 *
267 * Returns zero on success, or -EFAULT on error.
268 * On error, the variable @x is set to zero.
269 */
270#define __get_user(x,ptr) \
271 __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
272
273
274/**
275 * __put_user: - Write a simple value into user space, with less checking.
276 * @x: Value to copy to user space.
277 * @ptr: Destination address, in user space.
278 *
279 * Context: User context only. This function may sleep.
280 *
281 * This macro copies a single simple value from kernel space to user
282 * space. It supports simple types like char and int, but not larger
283 * data types like structures or arrays.
284 *
285 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
286 * to the result of dereferencing @ptr.
287 *
288 * Caller must check the pointer with access_ok() before calling this
289 * function.
290 *
291 * Returns zero on success, or -EFAULT on error.
292 */
293#define __put_user(x,ptr) \
294 __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
295
296#define __put_user_nocheck(x,ptr,size) \
297({ \
298 long __pu_err; \
299 __put_user_size((x),(ptr),(size),__pu_err,-EFAULT); \
300 __pu_err; \
301})
302
303
304#define __put_user_u64(x, addr, err) \
305 __asm__ __volatile__( \
306 "1: movl %%eax,0(%2)\n" \
307 "2: movl %%edx,4(%2)\n" \
308 "3:\n" \
309 ".section .fixup,\"ax\"\n" \
310 "4: movl %3,%0\n" \
311 " jmp 3b\n" \
312 ".previous\n" \
313 ".section __ex_table,\"a\"\n" \
314 " .align 4\n" \
315 " .long 1b,4b\n" \
316 " .long 2b,4b\n" \
317 ".previous" \
318 : "=r"(err) \
319 : "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))
320
321#ifdef CONFIG_X86_WP_WORKS_OK
322
323#define __put_user_size(x,ptr,size,retval,errret) \
324do { \
325 retval = 0; \
326 __chk_user_ptr(ptr); \
327 switch (size) { \
328 case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break; \
329 case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
330 case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break; \
331 case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
332 default: __put_user_bad(); \
333 } \
334} while (0)
335
336#else
337
338#define __put_user_size(x,ptr,size,retval,errret) \
339do { \
340 __typeof__(*(ptr)) __pus_tmp = x; \
341 retval = 0; \
342 \
343 if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0)) \
344 retval = errret; \
345} while (0)
346
347#endif
348struct __large_struct { unsigned long buf[100]; };
349#define __m(x) (*(struct __large_struct __user *)(x))
350
351/*
352 * Tell gcc we read from memory instead of writing: this is because
353 * we do not write to any memory gcc knows about, so there are no
354 * aliasing issues.
355 */
356#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
357 __asm__ __volatile__( \
358 "1: mov"itype" %"rtype"1,%2\n" \
359 "2:\n" \
360 ".section .fixup,\"ax\"\n" \
361 "3: movl %3,%0\n" \
362 " jmp 2b\n" \
363 ".previous\n" \
364 ".section __ex_table,\"a\"\n" \
365 " .align 4\n" \
366 " .long 1b,3b\n" \
367 ".previous" \
368 : "=r"(err) \
369 : ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))
370
371
372#define __get_user_nocheck(x,ptr,size) \
373({ \
374 long __gu_err; \
375 unsigned long __gu_val; \
376 __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
377 (x) = (__typeof__(*(ptr)))__gu_val; \
378 __gu_err; \
379})
380
381extern long __get_user_bad(void);
382
383#define __get_user_size(x,ptr,size,retval,errret) \
384do { \
385 retval = 0; \
386 __chk_user_ptr(ptr); \
387 switch (size) { \
388 case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break; \
389 case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break; \
390 case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break; \
391 default: (x) = __get_user_bad(); \
392 } \
393} while (0)
394
395#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
396 __asm__ __volatile__( \
397 "1: mov"itype" %2,%"rtype"1\n" \
398 "2:\n" \
399 ".section .fixup,\"ax\"\n" \
400 "3: movl %3,%0\n" \
401 " xor"itype" %"rtype"1,%"rtype"1\n" \
402 " jmp 2b\n" \
403 ".previous\n" \
404 ".section __ex_table,\"a\"\n" \
405 " .align 4\n" \
406 " .long 1b,3b\n" \
407 ".previous" \
408 : "=r"(err), ltype (x) \
409 : "m"(__m(addr)), "i"(errret), "0"(err))
410
411
412unsigned long __must_check __copy_to_user_ll(void __user *to,
413 const void *from, unsigned long n);
414unsigned long __must_check __copy_from_user_ll(void *to,
415 const void __user *from, unsigned long n);
416
417/*
418 * Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
419 * we return the initial request size (1, 2 or 4), as copy_*_user should do.
420 * If a store crosses a page boundary and gets a fault, the x86 will not write
421 * anything, so this is accurate.
422 */
423
424/**
425 * __copy_to_user: - Copy a block of data into user space, with less checking.
426 * @to: Destination address, in user space.
427 * @from: Source address, in kernel space.
428 * @n: Number of bytes to copy.
429 *
430 * Context: User context only. This function may sleep.
431 *
432 * Copy data from kernel space to user space. Caller must check
433 * the specified block with access_ok() before calling this function.
434 *
435 * Returns number of bytes that could not be copied.
436 * On success, this will be zero.
437 */
438static inline unsigned long __must_check
439__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
440{
441 if (__builtin_constant_p(n)) {
442 unsigned long ret;
443
444 switch (n) {
445 case 1:
446 __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
447 return ret;
448 case 2:
449 __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
450 return ret;
451 case 4:
452 __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
453 return ret;
454 }
455 }
456 return __copy_to_user_ll(to, from, n);
457}
458
459static inline unsigned long __must_check
460__copy_to_user(void __user *to, const void *from, unsigned long n)
461{
462 might_sleep();
463 return __copy_to_user_inatomic(to, from, n);
464}
465
466/**
467 * __copy_from_user: - Copy a block of data from user space, with less checking.
468 * @to: Destination address, in kernel space.
469 * @from: Source address, in user space.
470 * @n: Number of bytes to copy.
471 *
472 * Context: User context only. This function may sleep.
473 *
474 * Copy data from user space to kernel space. Caller must check
475 * the specified block with access_ok() before calling this function.
476 *
477 * Returns number of bytes that could not be copied.
478 * On success, this will be zero.
479 *
480 * If some data could not be copied, this function will pad the copied
481 * data to the requested size using zero bytes.
482 */
483static inline unsigned long
484__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
485{
486 if (__builtin_constant_p(n)) {
487 unsigned long ret;
488
489 switch (n) {
490 case 1:
491 __get_user_size(*(u8 *)to, from, 1, ret, 1);
492 return ret;
493 case 2:
494 __get_user_size(*(u16 *)to, from, 2, ret, 2);
495 return ret;
496 case 4:
497 __get_user_size(*(u32 *)to, from, 4, ret, 4);
498 return ret;
499 }
500 }
501 return __copy_from_user_ll(to, from, n);
502}
503
504static inline unsigned long
505__copy_from_user(void *to, const void __user *from, unsigned long n)
506{
507 might_sleep();
508 return __copy_from_user_inatomic(to, from, n);
509}
510unsigned long __must_check copy_to_user(void __user *to,
511 const void *from, unsigned long n);
512unsigned long __must_check copy_from_user(void *to,
513 const void __user *from, unsigned long n);
514long __must_check strncpy_from_user(char *dst, const char __user *src,
515 long count);
516long __must_check __strncpy_from_user(char *dst,
517 const char __user *src, long count);
518
519/**
520 * strlen_user: - Get the size of a string in user space.
521 * @str: The string to measure.
522 *
523 * Context: User context only. This function may sleep.
524 *
525 * Get the size of a NUL-terminated string in user space.
526 *
527 * Returns the size of the string INCLUDING the terminating NUL.
528 * On exception, returns 0.
529 *
530 * If there is a limit on the length of a valid string, you may wish to
531 * consider using strnlen_user() instead.
532 */
533#define strlen_user(str) strnlen_user(str, ~0UL >> 1)
534
535long strnlen_user(const char __user *str, long n);
536unsigned long __must_check clear_user(void __user *mem, unsigned long len);
537unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
538
539#endif /* __i386_UACCESS_H */