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1 #ifndef __i386_UACCESS_H
2 #define __i386_UACCESS_H
3 
4 /*
5  * User space memory access functions
6  */
7 #include <linux/errno.h>
8 #include <linux/thread_info.h>
9 #include <linux/prefetch.h>
10 #include <linux/string.h>
11 #include <asm/page.h>
12 
13 #define VERIFY_READ 0
14 #define VERIFY_WRITE 1
15 
16 /*
17  * The fs value determines whether argument validity checking should be
18  * performed or not.  If get_fs() == USER_DS, checking is performed, with
19  * get_fs() == KERNEL_DS, checking is bypassed.
20  *
21  * For historical reasons, these macros are grossly misnamed.
22  */
23 
24 #define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
25 
26 
27 #define KERNEL_DS	MAKE_MM_SEG(0xFFFFFFFFUL)
28 #define USER_DS		MAKE_MM_SEG(PAGE_OFFSET)
29 
30 #define get_ds()	(KERNEL_DS)
31 #define get_fs()	(current_thread_info()->addr_limit)
32 #define set_fs(x)	(current_thread_info()->addr_limit = (x))
33 
34 #define segment_eq(a,b)	((a).seg == (b).seg)
35 
36 /*
37  * movsl can be slow when source and dest are not both 8-byte aligned
38  */
39 #ifdef CONFIG_X86_INTEL_USERCOPY
40 extern struct movsl_mask {
41 	int mask;
42 } ____cacheline_aligned_in_smp movsl_mask;
43 #endif
44 
45 #define __addr_ok(addr) ((unsigned long __force)(addr) < (current_thread_info()->addr_limit.seg))
46 
47 /*
48  * Test whether a block of memory is a valid user space address.
49  * Returns 0 if the range is valid, nonzero otherwise.
50  *
51  * This is equivalent to the following test:
52  * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
53  *
54  * This needs 33-bit arithmetic. We have a carry...
55  */
56 #define __range_ok(addr,size) ({ \
57 	unsigned long flag,roksum; \
58 	__chk_user_ptr(addr); \
59 	asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
60 		:"=&r" (flag), "=r" (roksum) \
61 		:"1" (addr),"g" ((int)(size)),"rm" (current_thread_info()->addr_limit.seg)); \
62 	flag; })
63 
64 /**
65  * access_ok: - Checks if a user space pointer is valid
66  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
67  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
68  *        to write to a block, it is always safe to read from it.
69  * @addr: User space pointer to start of block to check
70  * @size: Size of block to check
71  *
72  * Context: User context only.  This function may sleep.
73  *
74  * Checks if a pointer to a block of memory in user space is valid.
75  *
76  * Returns true (nonzero) if the memory block may be valid, false (zero)
77  * if it is definitely invalid.
78  *
79  * Note that, depending on architecture, this function probably just
80  * checks that the pointer is in the user space range - after calling
81  * this function, memory access functions may still return -EFAULT.
82  */
83 #define access_ok(type,addr,size) (likely(__range_ok(addr,size) == 0))
84 
85 /*
86  * The exception table consists of pairs of addresses: the first is the
87  * address of an instruction that is allowed to fault, and the second is
88  * the address at which the program should continue.  No registers are
89  * modified, so it is entirely up to the continuation code to figure out
90  * what to do.
91  *
92  * All the routines below use bits of fixup code that are out of line
93  * with the main instruction path.  This means when everything is well,
94  * we don't even have to jump over them.  Further, they do not intrude
95  * on our cache or tlb entries.
96  */
97 
98 struct exception_table_entry
99 {
100 	unsigned long insn, fixup;
101 };
102 
103 extern int fixup_exception(struct pt_regs *regs);
104 
105 /*
106  * These are the main single-value transfer routines.  They automatically
107  * use the right size if we just have the right pointer type.
108  *
109  * This gets kind of ugly. We want to return _two_ values in "get_user()"
110  * and yet we don't want to do any pointers, because that is too much
111  * of a performance impact. Thus we have a few rather ugly macros here,
112  * and hide all the ugliness from the user.
113  *
114  * The "__xxx" versions of the user access functions are versions that
115  * do not verify the address space, that must have been done previously
116  * with a separate "access_ok()" call (this is used when we do multiple
117  * accesses to the same area of user memory).
118  */
119 
120 extern void __get_user_1(void);
121 extern void __get_user_2(void);
122 extern void __get_user_4(void);
123 
124 #define __get_user_x(size,ret,x,ptr) \
125 	__asm__ __volatile__("call __get_user_" #size \
126 		:"=a" (ret),"=d" (x) \
127 		:"0" (ptr))
128 
129 
130 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
131 /**
132  * get_user: - Get a simple variable from user space.
133  * @x:   Variable to store result.
134  * @ptr: Source address, in user space.
135  *
136  * Context: User context only.  This function may sleep.
137  *
138  * This macro copies a single simple variable from user space to kernel
139  * space.  It supports simple types like char and int, but not larger
140  * data types like structures or arrays.
141  *
142  * @ptr must have pointer-to-simple-variable type, and the result of
143  * dereferencing @ptr must be assignable to @x without a cast.
144  *
145  * Returns zero on success, or -EFAULT on error.
146  * On error, the variable @x is set to zero.
147  */
148 #define get_user(x,ptr)							\
149 ({	int __ret_gu;							\
150 	unsigned long __val_gu;						\
151 	__chk_user_ptr(ptr);						\
152 	switch(sizeof (*(ptr))) {					\
153 	case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;		\
154 	case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;		\
155 	case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;		\
156 	default: __get_user_x(X,__ret_gu,__val_gu,ptr); break;		\
157 	}								\
158 	(x) = (__typeof__(*(ptr)))__val_gu;				\
159 	__ret_gu;							\
160 })
161 
162 extern void __put_user_bad(void);
163 
164 /*
165  * Strange magic calling convention: pointer in %ecx,
166  * value in %eax(:%edx), return value in %eax, no clobbers.
167  */
168 extern void __put_user_1(void);
169 extern void __put_user_2(void);
170 extern void __put_user_4(void);
171 extern void __put_user_8(void);
172 
173 #define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
174 #define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
175 #define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
176 #define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu):"A" ((typeof(*(ptr)))(x)), "c" (ptr))
177 #define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a" (__ret_pu):"c" (ptr))
178 
179 /**
180  * put_user: - Write a simple value into user space.
181  * @x:   Value to copy to user space.
182  * @ptr: Destination address, in user space.
183  *
184  * Context: User context only.  This function may sleep.
185  *
186  * This macro copies a single simple value from kernel space to user
187  * space.  It supports simple types like char and int, but not larger
188  * data types like structures or arrays.
189  *
190  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
191  * to the result of dereferencing @ptr.
192  *
193  * Returns zero on success, or -EFAULT on error.
194  */
195 #ifdef CONFIG_X86_WP_WORKS_OK
196 
197 #define put_user(x,ptr)						\
198 ({	int __ret_pu;						\
199 	__typeof__(*(ptr)) __pu_val;				\
200 	__chk_user_ptr(ptr);					\
201 	__pu_val = x;						\
202 	switch(sizeof(*(ptr))) {				\
203 	case 1: __put_user_1(__pu_val, ptr); break;		\
204 	case 2: __put_user_2(__pu_val, ptr); break;		\
205 	case 4: __put_user_4(__pu_val, ptr); break;		\
206 	case 8: __put_user_8(__pu_val, ptr); break;		\
207 	default:__put_user_X(__pu_val, ptr); break;		\
208 	}							\
209 	__ret_pu;						\
210 })
211 
212 #else
213 #define put_user(x,ptr)						\
214 ({								\
215  	int __ret_pu;						\
216 	__typeof__(*(ptr)) __pus_tmp = x;			\
217 	__ret_pu=0;						\
218 	if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp,		\
219 				sizeof(*(ptr))) != 0))		\
220  		__ret_pu=-EFAULT;				\
221  	__ret_pu;						\
222  })
223 
224 
225 #endif
226 
227 /**
228  * __get_user: - Get a simple variable from user space, with less checking.
229  * @x:   Variable to store result.
230  * @ptr: Source address, in user space.
231  *
232  * Context: User context only.  This function may sleep.
233  *
234  * This macro copies a single simple variable from user space to kernel
235  * space.  It supports simple types like char and int, but not larger
236  * data types like structures or arrays.
237  *
238  * @ptr must have pointer-to-simple-variable type, and the result of
239  * dereferencing @ptr must be assignable to @x without a cast.
240  *
241  * Caller must check the pointer with access_ok() before calling this
242  * function.
243  *
244  * Returns zero on success, or -EFAULT on error.
245  * On error, the variable @x is set to zero.
246  */
247 #define __get_user(x,ptr) \
248   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
249 
250 
251 /**
252  * __put_user: - Write a simple value into user space, with less checking.
253  * @x:   Value to copy to user space.
254  * @ptr: Destination address, in user space.
255  *
256  * Context: User context only.  This function may sleep.
257  *
258  * This macro copies a single simple value from kernel space to user
259  * space.  It supports simple types like char and int, but not larger
260  * data types like structures or arrays.
261  *
262  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
263  * to the result of dereferencing @ptr.
264  *
265  * Caller must check the pointer with access_ok() before calling this
266  * function.
267  *
268  * Returns zero on success, or -EFAULT on error.
269  */
270 #define __put_user(x,ptr) \
271   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
272 
273 #define __put_user_nocheck(x,ptr,size)				\
274 ({								\
275 	long __pu_err;						\
276 	__put_user_size((x),(ptr),(size),__pu_err,-EFAULT);	\
277 	__pu_err;						\
278 })
279 
280 
281 #define __put_user_u64(x, addr, err)				\
282 	__asm__ __volatile__(					\
283 		"1:	movl %%eax,0(%2)\n"			\
284 		"2:	movl %%edx,4(%2)\n"			\
285 		"3:\n"						\
286 		".section .fixup,\"ax\"\n"			\
287 		"4:	movl %3,%0\n"				\
288 		"	jmp 3b\n"				\
289 		".previous\n"					\
290 		".section __ex_table,\"a\"\n"			\
291 		"	.align 4\n"				\
292 		"	.long 1b,4b\n"				\
293 		"	.long 2b,4b\n"				\
294 		".previous"					\
295 		: "=r"(err)					\
296 		: "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))
297 
298 #ifdef CONFIG_X86_WP_WORKS_OK
299 
300 #define __put_user_size(x,ptr,size,retval,errret)			\
301 do {									\
302 	retval = 0;							\
303 	__chk_user_ptr(ptr);						\
304 	switch (size) {							\
305 	case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break;	\
306 	case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
307 	case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break;	\
308 	case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
309 	  default: __put_user_bad();					\
310 	}								\
311 } while (0)
312 
313 #else
314 
315 #define __put_user_size(x,ptr,size,retval,errret)			\
316 do {									\
317 	__typeof__(*(ptr)) __pus_tmp = x;				\
318 	retval = 0;							\
319 									\
320 	if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))	\
321 		retval = errret;					\
322 } while (0)
323 
324 #endif
325 struct __large_struct { unsigned long buf[100]; };
326 #define __m(x) (*(struct __large_struct __user *)(x))
327 
328 /*
329  * Tell gcc we read from memory instead of writing: this is because
330  * we do not write to any memory gcc knows about, so there are no
331  * aliasing issues.
332  */
333 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
334 	__asm__ __volatile__(						\
335 		"1:	mov"itype" %"rtype"1,%2\n"			\
336 		"2:\n"							\
337 		".section .fixup,\"ax\"\n"				\
338 		"3:	movl %3,%0\n"					\
339 		"	jmp 2b\n"					\
340 		".previous\n"						\
341 		".section __ex_table,\"a\"\n"				\
342 		"	.align 4\n"					\
343 		"	.long 1b,3b\n"					\
344 		".previous"						\
345 		: "=r"(err)						\
346 		: ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))
347 
348 
349 #define __get_user_nocheck(x,ptr,size)				\
350 ({								\
351 	long __gu_err;						\
352 	unsigned long __gu_val;					\
353 	__get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
354 	(x) = (__typeof__(*(ptr)))__gu_val;			\
355 	__gu_err;						\
356 })
357 
358 extern long __get_user_bad(void);
359 
360 #define __get_user_size(x,ptr,size,retval,errret)			\
361 do {									\
362 	retval = 0;							\
363 	__chk_user_ptr(ptr);						\
364 	switch (size) {							\
365 	case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break;	\
366 	case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break;	\
367 	case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break;	\
368 	default: (x) = __get_user_bad();				\
369 	}								\
370 } while (0)
371 
372 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
373 	__asm__ __volatile__(						\
374 		"1:	mov"itype" %2,%"rtype"1\n"			\
375 		"2:\n"							\
376 		".section .fixup,\"ax\"\n"				\
377 		"3:	movl %3,%0\n"					\
378 		"	xor"itype" %"rtype"1,%"rtype"1\n"		\
379 		"	jmp 2b\n"					\
380 		".previous\n"						\
381 		".section __ex_table,\"a\"\n"				\
382 		"	.align 4\n"					\
383 		"	.long 1b,3b\n"					\
384 		".previous"						\
385 		: "=r"(err), ltype (x)					\
386 		: "m"(__m(addr)), "i"(errret), "0"(err))
387 
388 
389 unsigned long __must_check __copy_to_user_ll(void __user *to,
390 				const void *from, unsigned long n);
391 unsigned long __must_check __copy_from_user_ll(void *to,
392 				const void __user *from, unsigned long n);
393 unsigned long __must_check __copy_from_user_ll_nozero(void *to,
394 				const void __user *from, unsigned long n);
395 unsigned long __must_check __copy_from_user_ll_nocache(void *to,
396 				const void __user *from, unsigned long n);
397 unsigned long __must_check __copy_from_user_ll_nocache_nozero(void *to,
398 				const void __user *from, unsigned long n);
399 
400 /**
401  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
402  * @to:   Destination address, in user space.
403  * @from: Source address, in kernel space.
404  * @n:    Number of bytes to copy.
405  *
406  * Context: User context only.
407  *
408  * Copy data from kernel space to user space.  Caller must check
409  * the specified block with access_ok() before calling this function.
410  * The caller should also make sure he pins the user space address
411  * so that the we don't result in page fault and sleep.
412  *
413  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
414  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
415  * If a store crosses a page boundary and gets a fault, the x86 will not write
416  * anything, so this is accurate.
417  */
418 
419 static __always_inline unsigned long __must_check
__copy_to_user_inatomic(void __user * to,const void * from,unsigned long n)420 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
421 {
422 	if (__builtin_constant_p(n)) {
423 		unsigned long ret;
424 
425 		switch (n) {
426 		case 1:
427 			__put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
428 			return ret;
429 		case 2:
430 			__put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
431 			return ret;
432 		case 4:
433 			__put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
434 			return ret;
435 		}
436 	}
437 	return __copy_to_user_ll(to, from, n);
438 }
439 
440 /**
441  * __copy_to_user: - Copy a block of data into user space, with less checking.
442  * @to:   Destination address, in user space.
443  * @from: Source address, in kernel space.
444  * @n:    Number of bytes to copy.
445  *
446  * Context: User context only.  This function may sleep.
447  *
448  * Copy data from kernel space to user space.  Caller must check
449  * the specified block with access_ok() before calling this function.
450  *
451  * Returns number of bytes that could not be copied.
452  * On success, this will be zero.
453  */
454 static __always_inline unsigned long __must_check
__copy_to_user(void __user * to,const void * from,unsigned long n)455 __copy_to_user(void __user *to, const void *from, unsigned long n)
456 {
457        might_sleep();
458        return __copy_to_user_inatomic(to, from, n);
459 }
460 
461 static __always_inline unsigned long
__copy_from_user_inatomic(void * to,const void __user * from,unsigned long n)462 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
463 {
464 	/* Avoid zeroing the tail if the copy fails..
465 	 * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
466 	 * but as the zeroing behaviour is only significant when n is not
467 	 * constant, that shouldn't be a problem.
468 	 */
469 	if (__builtin_constant_p(n)) {
470 		unsigned long ret;
471 
472 		switch (n) {
473 		case 1:
474 			__get_user_size(*(u8 *)to, from, 1, ret, 1);
475 			return ret;
476 		case 2:
477 			__get_user_size(*(u16 *)to, from, 2, ret, 2);
478 			return ret;
479 		case 4:
480 			__get_user_size(*(u32 *)to, from, 4, ret, 4);
481 			return ret;
482 		}
483 	}
484 	return __copy_from_user_ll_nozero(to, from, n);
485 }
486 
487 /**
488  * __copy_from_user: - Copy a block of data from user space, with less checking.
489  * @to:   Destination address, in kernel space.
490  * @from: Source address, in user space.
491  * @n:    Number of bytes to copy.
492  *
493  * Context: User context only.  This function may sleep.
494  *
495  * Copy data from user space to kernel space.  Caller must check
496  * the specified block with access_ok() before calling this function.
497  *
498  * Returns number of bytes that could not be copied.
499  * On success, this will be zero.
500  *
501  * If some data could not be copied, this function will pad the copied
502  * data to the requested size using zero bytes.
503  *
504  * An alternate version - __copy_from_user_inatomic() - may be called from
505  * atomic context and will fail rather than sleep.  In this case the
506  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
507  * for explanation of why this is needed.
508  */
509 static __always_inline unsigned long
__copy_from_user(void * to,const void __user * from,unsigned long n)510 __copy_from_user(void *to, const void __user *from, unsigned long n)
511 {
512 	might_sleep();
513 	if (__builtin_constant_p(n)) {
514 		unsigned long ret;
515 
516 		switch (n) {
517 		case 1:
518 			__get_user_size(*(u8 *)to, from, 1, ret, 1);
519 			return ret;
520 		case 2:
521 			__get_user_size(*(u16 *)to, from, 2, ret, 2);
522 			return ret;
523 		case 4:
524 			__get_user_size(*(u32 *)to, from, 4, ret, 4);
525 			return ret;
526 		}
527 	}
528 	return __copy_from_user_ll(to, from, n);
529 }
530 
531 #define ARCH_HAS_NOCACHE_UACCESS
532 
__copy_from_user_nocache(void * to,const void __user * from,unsigned long n)533 static __always_inline unsigned long __copy_from_user_nocache(void *to,
534 				const void __user *from, unsigned long n)
535 {
536 	might_sleep();
537 	if (__builtin_constant_p(n)) {
538 		unsigned long ret;
539 
540 		switch (n) {
541 		case 1:
542 			__get_user_size(*(u8 *)to, from, 1, ret, 1);
543 			return ret;
544 		case 2:
545 			__get_user_size(*(u16 *)to, from, 2, ret, 2);
546 			return ret;
547 		case 4:
548 			__get_user_size(*(u32 *)to, from, 4, ret, 4);
549 			return ret;
550 		}
551 	}
552 	return __copy_from_user_ll_nocache(to, from, n);
553 }
554 
555 static __always_inline unsigned long
__copy_from_user_inatomic_nocache(void * to,const void __user * from,unsigned long n)556 __copy_from_user_inatomic_nocache(void *to, const void __user *from, unsigned long n)
557 {
558        return __copy_from_user_ll_nocache_nozero(to, from, n);
559 }
560 
561 unsigned long __must_check copy_to_user(void __user *to,
562 				const void *from, unsigned long n);
563 unsigned long __must_check copy_from_user(void *to,
564 				const void __user *from, unsigned long n);
565 long __must_check strncpy_from_user(char *dst, const char __user *src,
566 				long count);
567 long __must_check __strncpy_from_user(char *dst,
568 				const char __user *src, long count);
569 
570 /**
571  * strlen_user: - Get the size of a string in user space.
572  * @str: The string to measure.
573  *
574  * Context: User context only.  This function may sleep.
575  *
576  * Get the size of a NUL-terminated string in user space.
577  *
578  * Returns the size of the string INCLUDING the terminating NUL.
579  * On exception, returns 0.
580  *
581  * If there is a limit on the length of a valid string, you may wish to
582  * consider using strnlen_user() instead.
583  */
584 #define strlen_user(str) strnlen_user(str, LONG_MAX)
585 
586 long strnlen_user(const char __user *str, long n);
587 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
588 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
589 
590 #endif /* __i386_UACCESS_H */
591