1 #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
41 extern 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, use access_ok()
88 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE
89 * @addr: User space pointer to start of block to check
90 * @size: Size of block to check
91 *
92 * Context: User context only. This function may sleep.
93 *
94 * This function has been replaced by access_ok().
95 *
96 * Checks if a pointer to a block of memory in user space is valid.
97 *
98 * Returns zero if the memory block may be valid, -EFAULT
99 * if it is definitely invalid.
100 *
101 * See access_ok() for more details.
102 */
103 static inline int verify_area(int type, const void __user * addr, unsigned long size)
104 {
105 return access_ok(type,addr,size) ? 0 : -EFAULT;
106 }
107
108
109 /*
110 * The exception table consists of pairs of addresses: the first is the
111 * address of an instruction that is allowed to fault, and the second is
112 * the address at which the program should continue. No registers are
113 * modified, so it is entirely up to the continuation code to figure out
114 * what to do.
115 *
116 * All the routines below use bits of fixup code that are out of line
117 * with the main instruction path. This means when everything is well,
118 * we don't even have to jump over them. Further, they do not intrude
119 * on our cache or tlb entries.
120 */
121
122 struct exception_table_entry
123 {
124 unsigned long insn, fixup;
125 };
126
127 extern int fixup_exception(struct pt_regs *regs);
128
129 /*
130 * These are the main single-value transfer routines. They automatically
131 * use the right size if we just have the right pointer type.
132 *
133 * This gets kind of ugly. We want to return _two_ values in "get_user()"
134 * and yet we don't want to do any pointers, because that is too much
135 * of a performance impact. Thus we have a few rather ugly macros here,
136 * and hide all the ugliness from the user.
137 *
138 * The "__xxx" versions of the user access functions are versions that
139 * do not verify the address space, that must have been done previously
140 * with a separate "access_ok()" call (this is used when we do multiple
141 * accesses to the same area of user memory).
142 */
143
144 extern void __get_user_1(void);
145 extern void __get_user_2(void);
146 extern void __get_user_4(void);
147
148 #define __get_user_x(size,ret,x,ptr) \
149 __asm__ __volatile__("call __get_user_" #size \
150 :"=a" (ret),"=d" (x) \
151 :"" (ptr))
152
153
154 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
155 /**
156 * get_user: - Get a simple variable from user space.
157 * @x: Variable to store result.
158 * @ptr: Source address, in user space.
159 *
160 * Context: User context only. This function may sleep.
161 *
162 * This macro copies a single simple variable from user space to kernel
163 * space. It supports simple types like char and int, but not larger
164 * data types like structures or arrays.
165 *
166 * @ptr must have pointer-to-simple-variable type, and the result of
167 * dereferencing @ptr must be assignable to @x without a cast.
168 *
169 * Returns zero on success, or -EFAULT on error.
170 * On error, the variable @x is set to zero.
171 */
172 #define get_user(x,ptr) \
173 ({ int __ret_gu; \
174 unsigned long __val_gu; \
175 __chk_user_ptr(ptr); \
176 switch(sizeof (*(ptr))) { \
177 case 1: __get_user_x(1,__ret_gu,__val_gu,ptr); break; \
178 case 2: __get_user_x(2,__ret_gu,__val_gu,ptr); break; \
179 case 4: __get_user_x(4,__ret_gu,__val_gu,ptr); break; \
180 default: __get_user_x(X,__ret_gu,__val_gu,ptr); break; \
181 } \
182 (x) = (__typeof__(*(ptr)))__val_gu; \
183 __ret_gu; \
184 })
185
186 extern void __put_user_bad(void);
187
188 /**
189 * put_user: - Write a simple value into user space.
190 * @x: Value to copy to user space.
191 * @ptr: Destination address, in user space.
192 *
193 * Context: User context only. This function may sleep.
194 *
195 * This macro copies a single simple value from kernel space to user
196 * space. It supports simple types like char and int, but not larger
197 * data types like structures or arrays.
198 *
199 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
200 * to the result of dereferencing @ptr.
201 *
202 * Returns zero on success, or -EFAULT on error.
203 */
204 #define put_user(x,ptr) \
205 __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
206
207
208 /**
209 * __get_user: - Get a simple variable from user space, with less checking.
210 * @x: Variable to store result.
211 * @ptr: Source address, in user space.
212 *
213 * Context: User context only. This function may sleep.
214 *
215 * This macro copies a single simple variable from user space to kernel
216 * space. It supports simple types like char and int, but not larger
217 * data types like structures or arrays.
218 *
219 * @ptr must have pointer-to-simple-variable type, and the result of
220 * dereferencing @ptr must be assignable to @x without a cast.
221 *
222 * Caller must check the pointer with access_ok() before calling this
223 * function.
224 *
225 * Returns zero on success, or -EFAULT on error.
226 * On error, the variable @x is set to zero.
227 */
228 #define __get_user(x,ptr) \
229 __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
230
231
232 /**
233 * __put_user: - Write a simple value into user space, with less checking.
234 * @x: Value to copy to user space.
235 * @ptr: Destination address, in user space.
236 *
237 * Context: User context only. This function may sleep.
238 *
239 * This macro copies a single simple value from kernel space to user
240 * space. It supports simple types like char and int, but not larger
241 * data types like structures or arrays.
242 *
243 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
244 * to the result of dereferencing @ptr.
245 *
246 * Caller must check the pointer with access_ok() before calling this
247 * function.
248 *
249 * Returns zero on success, or -EFAULT on error.
250 */
251 #define __put_user(x,ptr) \
252 __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
253
254 #define __put_user_nocheck(x,ptr,size) \
255 ({ \
256 long __pu_err; \
257 __put_user_size((x),(ptr),(size),__pu_err,-EFAULT); \
258 __pu_err; \
259 })
260
261
262 #define __put_user_check(x,ptr,size) \
263 ({ \
264 long __pu_err = -EFAULT; \
265 __typeof__(*(ptr)) __user *__pu_addr = (ptr); \
266 might_sleep(); \
267 if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
268 __put_user_size((x),__pu_addr,(size),__pu_err,-EFAULT); \
269 __pu_err; \
270 })
271
272 #define __put_user_u64(x, addr, err) \
273 __asm__ __volatile__( \
274 "1: movl %%eax,0(%2)\n" \
275 "2: movl %%edx,4(%2)\n" \
276 "3:\n" \
277 ".section .fixup,\"ax\"\n" \
278 "4: movl %3,%0\n" \
279 " jmp 3b\n" \
280 ".previous\n" \
281 ".section __ex_table,\"a\"\n" \
282 " .align 4\n" \
283 " .long 1b,4b\n" \
284 " .long 2b,4b\n" \
285 ".previous" \
286 : "=r"(err) \
287 : "A" (x), "r" (addr), "i"(-EFAULT), ""(err))
288
289 #ifdef CONFIG_X86_WP_WORKS_OK
290
291 #define __put_user_size(x,ptr,size,retval,errret) \
292 do { \
293 retval = 0; \
294 __chk_user_ptr(ptr); \
295 switch (size) { \
296 case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break; \
297 case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
298 case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break; \
299 case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
300 default: __put_user_bad(); \
301 } \
302 } while (0)
303
304 #else
305
306 #define __put_user_size(x,ptr,size,retval,errret) \
307 do { \
308 __typeof__(*(ptr)) __pus_tmp = x; \
309 retval = 0; \
310 \
311 if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0)) \
312 retval = errret; \
313 } while (0)
314
315 #endif
316 struct __large_struct { unsigned long buf[100]; };
317 #define __m(x) (*(struct __large_struct __user *)(x))
318
319 /*
320 * Tell gcc we read from memory instead of writing: this is because
321 * we do not write to any memory gcc knows about, so there are no
322 * aliasing issues.
323 */
324 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
325 __asm__ __volatile__( \
326 "1: mov"itype" %"rtype"1,%2\n" \
327 "2:\n" \
328 ".section .fixup,\"ax\"\n" \
329 "3: movl %3,%0\n" \
330 " jmp 2b\n" \
331 ".previous\n" \
332 ".section __ex_table,\"a\"\n" \
333 " .align 4\n" \
334 " .long 1b,3b\n" \
335 ".previous" \
336 : "=r"(err) \
337 : ltype (x), "m"(__m(addr)), "i"(errret), ""(err))
338
339
340 #define __get_user_nocheck(x,ptr,size) \
341 ({ \
342 long __gu_err; \
343 unsigned long __gu_val; \
344 __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
345 (x) = (__typeof__(*(ptr)))__gu_val; \
346 __gu_err; \
347 })
348
349 extern long __get_user_bad(void);
350
351 #define __get_user_size(x,ptr,size,retval,errret) \
352 do { \
353 retval = 0; \
354 __chk_user_ptr(ptr); \
355 switch (size) { \
356 case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break; \
357 case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break; \
358 case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break; \
359 default: (x) = __get_user_bad(); \
360 } \
361 } while (0)
362
363 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
364 __asm__ __volatile__( \
365 "1: mov"itype" %2,%"rtype"1\n" \
366 "2:\n" \
367 ".section .fixup,\"ax\"\n" \
368 "3: movl %3,%0\n" \
369 " xor"itype" %"rtype"1,%"rtype"1\n" \
370 " jmp 2b\n" \
371 ".previous\n" \
372 ".section __ex_table,\"a\"\n" \
373 " .align 4\n" \
374 " .long 1b,3b\n" \
375 ".previous" \
376 : "=r"(err), ltype (x) \
377 : "m"(__m(addr)), "i"(errret), ""(err))
378
379
380 unsigned long __must_check __copy_to_user_ll(void __user *to,
381 const void *from, unsigned long n);
382 unsigned long __must_check __copy_from_user_ll(void *to,
383 const void __user *from, unsigned long n);
384
385 /*
386 * Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
387 * we return the initial request size (1, 2 or 4), as copy_*_user should do.
388 * If a store crosses a page boundary and gets a fault, the x86 will not write
389 * anything, so this is accurate.
390 */
391
392 /**
393 * __copy_to_user: - Copy a block of data into user space, with less checking.
394 * @to: Destination address, in user space.
395 * @from: Source address, in kernel space.
396 * @n: Number of bytes to copy.
397 *
398 * Context: User context only. This function may sleep.
399 *
400 * Copy data from kernel space to user space. Caller must check
401 * the specified block with access_ok() before calling this function.
402 *
403 * Returns number of bytes that could not be copied.
404 * On success, this will be zero.
405 */
406 static inline unsigned long __must_check
407 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
408 {
409 if (__builtin_constant_p(n)) {
410 unsigned long ret;
411
412 switch (n) {
413 case 1:
414 __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
415 return ret;
416 case 2:
417 __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
418 return ret;
419 case 4:
420 __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
421 return ret;
422 }
423 }
424 return __copy_to_user_ll(to, from, n);
425 }
426
427 static inline unsigned long __must_check
428 __copy_to_user(void __user *to, const void *from, unsigned long n)
429 {
430 might_sleep();
431 return __copy_to_user_inatomic(to, from, n);
432 }
433
434 /**
435 * __copy_from_user: - Copy a block of data from user space, with less checking.
436 * @to: Destination address, in kernel space.
437 * @from: Source address, in user space.
438 * @n: Number of bytes to copy.
439 *
440 * Context: User context only. This function may sleep.
441 *
442 * Copy data from user space to kernel space. Caller must check
443 * the specified block with access_ok() before calling this function.
444 *
445 * Returns number of bytes that could not be copied.
446 * On success, this will be zero.
447 *
448 * If some data could not be copied, this function will pad the copied
449 * data to the requested size using zero bytes.
450 */
451 static inline unsigned long
452 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
453 {
454 if (__builtin_constant_p(n)) {
455 unsigned long ret;
456
457 switch (n) {
458 case 1:
459 __get_user_size(*(u8 *)to, from, 1, ret, 1);
460 return ret;
461 case 2:
462 __get_user_size(*(u16 *)to, from, 2, ret, 2);
463 return ret;
464 case 4:
465 __get_user_size(*(u32 *)to, from, 4, ret, 4);
466 return ret;
467 }
468 }
469 return __copy_from_user_ll(to, from, n);
470 }
471
472 static inline unsigned long
473 __copy_from_user(void *to, const void __user *from, unsigned long n)
474 {
475 might_sleep();
476 return __copy_from_user_inatomic(to, from, n);
477 }
478 unsigned long __must_check copy_to_user(void __user *to,
479 const void *from, unsigned long n);
480 unsigned long __must_check copy_from_user(void *to,
481 const void __user *from, unsigned long n);
482 long __must_check strncpy_from_user(char *dst, const char __user *src,
483 long count);
484 long __must_check __strncpy_from_user(char *dst,
485 const char __user *src, long count);
486
487 /**
488 * strlen_user: - Get the size of a string in user space.
489 * @str: The string to measure.
490 *
491 * Context: User context only. This function may sleep.
492 *
493 * Get the size of a NUL-terminated string in user space.
494 *
495 * Returns the size of the string INCLUDING the terminating NUL.
496 * On exception, returns 0.
497 *
498 * If there is a limit on the length of a valid string, you may wish to
499 * consider using strnlen_user() instead.
500 */
501 #define strlen_user(str) strnlen_user(str, ~0UL >> 1)
502
503 long strnlen_user(const char __user *str, long n);
504 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
505 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
506
507 #endif /* __i386_UACCESS_H */
508
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