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1 #ifndef _ASM_X86_UACCESS_H
2 #define _ASM_X86_UACCESS_H
3 /*
4  * User space memory access functions
5  */
6 #include <linux/errno.h>
7 #include <linux/compiler.h>
8 #include <linux/thread_info.h>
9 #include <linux/string.h>
10 #include <asm/asm.h>
11 #include <asm/page.h>
12 #include <asm/smap.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 #define KERNEL_DS	MAKE_MM_SEG(-1UL)
28 #define USER_DS 	MAKE_MM_SEG(TASK_SIZE_MAX)
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 #define user_addr_max() (current_thread_info()->addr_limit.seg)
37 #define __addr_ok(addr) 	\
38 	((unsigned long __force)(addr) < user_addr_max())
39 
40 /*
41  * Test whether a block of memory is a valid user space address.
42  * Returns 0 if the range is valid, nonzero otherwise.
43  */
__chk_range_not_ok(unsigned long addr,unsigned long size,unsigned long limit)44 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
45 {
46 	/*
47 	 * If we have used "sizeof()" for the size,
48 	 * we know it won't overflow the limit (but
49 	 * it might overflow the 'addr', so it's
50 	 * important to subtract the size from the
51 	 * limit, not add it to the address).
52 	 */
53 	if (__builtin_constant_p(size))
54 		return addr > limit - size;
55 
56 	/* Arbitrary sizes? Be careful about overflow */
57 	addr += size;
58 	if (addr < size)
59 		return true;
60 	return addr > limit;
61 }
62 
63 #define __range_not_ok(addr, size, limit)				\
64 ({									\
65 	__chk_user_ptr(addr);						\
66 	__chk_range_not_ok((unsigned long __force)(addr), size, limit); \
67 })
68 
69 /**
70  * access_ok: - Checks if a user space pointer is valid
71  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
72  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
73  *        to write to a block, it is always safe to read from it.
74  * @addr: User space pointer to start of block to check
75  * @size: Size of block to check
76  *
77  * Context: User context only.  This function may sleep.
78  *
79  * Checks if a pointer to a block of memory in user space is valid.
80  *
81  * Returns true (nonzero) if the memory block may be valid, false (zero)
82  * if it is definitely invalid.
83  *
84  * Note that, depending on architecture, this function probably just
85  * checks that the pointer is in the user space range - after calling
86  * this function, memory access functions may still return -EFAULT.
87  */
88 #define access_ok(type, addr, size) \
89 	likely(!__range_not_ok(addr, size, user_addr_max()))
90 
91 /*
92  * The exception table consists of pairs of addresses relative to the
93  * exception table enty itself: the first is the address of an
94  * instruction that is allowed to fault, and the second is the address
95  * at which the program should continue.  No registers are modified,
96  * so it is entirely up to the continuation code to figure out what to
97  * do.
98  *
99  * All the routines below use bits of fixup code that are out of line
100  * with the main instruction path.  This means when everything is well,
101  * we don't even have to jump over them.  Further, they do not intrude
102  * on our cache or tlb entries.
103  */
104 
105 struct exception_table_entry {
106 	int insn, fixup;
107 };
108 /* This is not the generic standard exception_table_entry format */
109 #define ARCH_HAS_SORT_EXTABLE
110 #define ARCH_HAS_SEARCH_EXTABLE
111 
112 extern int fixup_exception(struct pt_regs *regs);
113 extern int early_fixup_exception(unsigned long *ip);
114 
115 /*
116  * These are the main single-value transfer routines.  They automatically
117  * use the right size if we just have the right pointer type.
118  *
119  * This gets kind of ugly. We want to return _two_ values in "get_user()"
120  * and yet we don't want to do any pointers, because that is too much
121  * of a performance impact. Thus we have a few rather ugly macros here,
122  * and hide all the ugliness from the user.
123  *
124  * The "__xxx" versions of the user access functions are versions that
125  * do not verify the address space, that must have been done previously
126  * with a separate "access_ok()" call (this is used when we do multiple
127  * accesses to the same area of user memory).
128  */
129 
130 extern int __get_user_1(void);
131 extern int __get_user_2(void);
132 extern int __get_user_4(void);
133 extern int __get_user_8(void);
134 extern int __get_user_bad(void);
135 
136 #define __uaccess_begin() stac()
137 #define __uaccess_end()   clac()
138 
139 /*
140  * This is a type: either unsigned long, if the argument fits into
141  * that type, or otherwise unsigned long long.
142  */
143 #define __inttype(x) \
144 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
145 
146 /**
147  * get_user: - Get a simple variable from user space.
148  * @x:   Variable to store result.
149  * @ptr: Source address, in user space.
150  *
151  * Context: User context only.  This function may sleep.
152  *
153  * This macro copies a single simple variable from user space to kernel
154  * space.  It supports simple types like char and int, but not larger
155  * data types like structures or arrays.
156  *
157  * @ptr must have pointer-to-simple-variable type, and the result of
158  * dereferencing @ptr must be assignable to @x without a cast.
159  *
160  * Returns zero on success, or -EFAULT on error.
161  * On error, the variable @x is set to zero.
162  */
163 /*
164  * Careful: we have to cast the result to the type of the pointer
165  * for sign reasons.
166  *
167  * The use of _ASM_DX as the register specifier is a bit of a
168  * simplification, as gcc only cares about it as the starting point
169  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
170  * (%ecx being the next register in gcc's x86 register sequence), and
171  * %rdx on 64 bits.
172  *
173  * Clang/LLVM cares about the size of the register, but still wants
174  * the base register for something that ends up being a pair.
175  */
176 #define get_user(x, ptr)						\
177 ({									\
178 	int __ret_gu;							\
179 	register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);		\
180 	__chk_user_ptr(ptr);						\
181 	might_fault();							\
182 	asm volatile("call __get_user_%P3"				\
183 		     : "=a" (__ret_gu), "=r" (__val_gu)			\
184 		     : "0" (ptr), "i" (sizeof(*(ptr))));		\
185 	(x) = (__force __typeof__(*(ptr))) __val_gu;			\
186 	__builtin_expect(__ret_gu, 0);					\
187 })
188 
189 #define __put_user_x(size, x, ptr, __ret_pu)			\
190 	asm volatile("call __put_user_" #size : "=a" (__ret_pu)	\
191 		     : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
192 
193 
194 
195 #ifdef CONFIG_X86_32
196 #define __put_user_asm_u64(x, addr, err, errret)			\
197 	asm volatile("\n"						\
198 		     "1:	movl %%eax,0(%2)\n"			\
199 		     "2:	movl %%edx,4(%2)\n"			\
200 		     "3:"						\
201 		     ".section .fixup,\"ax\"\n"				\
202 		     "4:	movl %3,%0\n"				\
203 		     "	jmp 3b\n"					\
204 		     ".previous\n"					\
205 		     _ASM_EXTABLE(1b, 4b)				\
206 		     _ASM_EXTABLE(2b, 4b)				\
207 		     : "=r" (err)					\
208 		     : "A" (x), "r" (addr), "i" (errret), "0" (err))
209 
210 #define __put_user_asm_ex_u64(x, addr)					\
211 	asm volatile("\n"						\
212 		     "1:	movl %%eax,0(%1)\n"			\
213 		     "2:	movl %%edx,4(%1)\n"			\
214 		     "3:"						\
215 		     _ASM_EXTABLE_EX(1b, 2b)				\
216 		     _ASM_EXTABLE_EX(2b, 3b)				\
217 		     : : "A" (x), "r" (addr))
218 
219 #define __put_user_x8(x, ptr, __ret_pu)				\
220 	asm volatile("call __put_user_8" : "=a" (__ret_pu)	\
221 		     : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
222 #else
223 #define __put_user_asm_u64(x, ptr, retval, errret) \
224 	__put_user_asm(x, ptr, retval, "q", "", "er", errret)
225 #define __put_user_asm_ex_u64(x, addr)	\
226 	__put_user_asm_ex(x, addr, "q", "", "er")
227 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
228 #endif
229 
230 extern void __put_user_bad(void);
231 
232 /*
233  * Strange magic calling convention: pointer in %ecx,
234  * value in %eax(:%edx), return value in %eax. clobbers %rbx
235  */
236 extern void __put_user_1(void);
237 extern void __put_user_2(void);
238 extern void __put_user_4(void);
239 extern void __put_user_8(void);
240 
241 /**
242  * put_user: - Write a simple value into user space.
243  * @x:   Value to copy to user space.
244  * @ptr: Destination address, in user space.
245  *
246  * Context: User context only.  This function may sleep.
247  *
248  * This macro copies a single simple value from kernel space to user
249  * space.  It supports simple types like char and int, but not larger
250  * data types like structures or arrays.
251  *
252  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
253  * to the result of dereferencing @ptr.
254  *
255  * Returns zero on success, or -EFAULT on error.
256  */
257 #define put_user(x, ptr)					\
258 ({								\
259 	int __ret_pu;						\
260 	__typeof__(*(ptr)) __pu_val;				\
261 	__chk_user_ptr(ptr);					\
262 	might_fault();						\
263 	__pu_val = x;						\
264 	switch (sizeof(*(ptr))) {				\
265 	case 1:							\
266 		__put_user_x(1, __pu_val, ptr, __ret_pu);	\
267 		break;						\
268 	case 2:							\
269 		__put_user_x(2, __pu_val, ptr, __ret_pu);	\
270 		break;						\
271 	case 4:							\
272 		__put_user_x(4, __pu_val, ptr, __ret_pu);	\
273 		break;						\
274 	case 8:							\
275 		__put_user_x8(__pu_val, ptr, __ret_pu);		\
276 		break;						\
277 	default:						\
278 		__put_user_x(X, __pu_val, ptr, __ret_pu);	\
279 		break;						\
280 	}							\
281 	__builtin_expect(__ret_pu, 0);				\
282 })
283 
284 #define __put_user_size(x, ptr, size, retval, errret)			\
285 do {									\
286 	retval = 0;							\
287 	__chk_user_ptr(ptr);						\
288 	switch (size) {							\
289 	case 1:								\
290 		__put_user_asm(x, ptr, retval, "b", "b", "iq", errret);	\
291 		break;							\
292 	case 2:								\
293 		__put_user_asm(x, ptr, retval, "w", "w", "ir", errret);	\
294 		break;							\
295 	case 4:								\
296 		__put_user_asm(x, ptr, retval, "l", "k", "ir", errret);	\
297 		break;							\
298 	case 8:								\
299 		__put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,	\
300 				   errret);				\
301 		break;							\
302 	default:							\
303 		__put_user_bad();					\
304 	}								\
305 } while (0)
306 
307 /*
308  * This doesn't do __uaccess_begin/end - the exception handling
309  * around it must do that.
310  */
311 #define __put_user_size_ex(x, ptr, size)				\
312 do {									\
313 	__chk_user_ptr(ptr);						\
314 	switch (size) {							\
315 	case 1:								\
316 		__put_user_asm_ex(x, ptr, "b", "b", "iq");		\
317 		break;							\
318 	case 2:								\
319 		__put_user_asm_ex(x, ptr, "w", "w", "ir");		\
320 		break;							\
321 	case 4:								\
322 		__put_user_asm_ex(x, ptr, "l", "k", "ir");		\
323 		break;							\
324 	case 8:								\
325 		__put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);	\
326 		break;							\
327 	default:							\
328 		__put_user_bad();					\
329 	}								\
330 } while (0)
331 
332 #ifdef CONFIG_X86_32
333 #define __get_user_asm_u64(x, ptr, retval, errret)	(x) = __get_user_bad()
334 #define __get_user_asm_ex_u64(x, ptr)			(x) = __get_user_bad()
335 #else
336 #define __get_user_asm_u64(x, ptr, retval, errret) \
337 	 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
338 #define __get_user_asm_ex_u64(x, ptr) \
339 	 __get_user_asm_ex(x, ptr, "q", "", "=&r")
340 #endif
341 
342 #define __get_user_size(x, ptr, size, retval, errret)			\
343 do {									\
344 	retval = 0;							\
345 	__chk_user_ptr(ptr);						\
346 	switch (size) {							\
347 	case 1:								\
348 		__get_user_asm(x, ptr, retval, "b", "b", "=q", errret);	\
349 		break;							\
350 	case 2:								\
351 		__get_user_asm(x, ptr, retval, "w", "w", "=r", errret);	\
352 		break;							\
353 	case 4:								\
354 		__get_user_asm(x, ptr, retval, "l", "k", "=r", errret);	\
355 		break;							\
356 	case 8:								\
357 		__get_user_asm_u64(x, ptr, retval, errret);		\
358 		break;							\
359 	default:							\
360 		(x) = __get_user_bad();					\
361 	}								\
362 } while (0)
363 
364 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
365 	asm volatile("\n"						\
366 		     "1:	mov"itype" %2,%"rtype"1\n"		\
367 		     "2:\n"						\
368 		     ".section .fixup,\"ax\"\n"				\
369 		     "3:	mov %3,%0\n"				\
370 		     "	xor"itype" %"rtype"1,%"rtype"1\n"		\
371 		     "	jmp 2b\n"					\
372 		     ".previous\n"					\
373 		     _ASM_EXTABLE(1b, 3b)				\
374 		     : "=r" (err), ltype(x)				\
375 		     : "m" (__m(addr)), "i" (errret), "0" (err))
376 
377 /*
378  * This doesn't do __uaccess_begin/end - the exception handling
379  * around it must do that.
380  */
381 #define __get_user_size_ex(x, ptr, size)				\
382 do {									\
383 	__chk_user_ptr(ptr);						\
384 	switch (size) {							\
385 	case 1:								\
386 		__get_user_asm_ex(x, ptr, "b", "b", "=&q");		\
387 		break;							\
388 	case 2:								\
389 		__get_user_asm_ex(x, ptr, "w", "w", "=&r");		\
390 		break;							\
391 	case 4:								\
392 		__get_user_asm_ex(x, ptr, "l", "k", "=&r");		\
393 		break;							\
394 	case 8:								\
395 		__get_user_asm_ex_u64(x, ptr);				\
396 		break;							\
397 	default:							\
398 		(x) = __get_user_bad();					\
399 	}								\
400 } while (0)
401 
402 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)			\
403 	asm volatile("1:	mov"itype" %1,%"rtype"0\n"		\
404 		     "2:\n"						\
405 		     ".section .fixup,\"ax\"\n"				\
406                      "3:xor"itype" %"rtype"0,%"rtype"0\n"		\
407 		     "  jmp 2b\n"					\
408 		     ".previous\n"					\
409 		     _ASM_EXTABLE_EX(1b, 3b)				\
410 		     : ltype(x) : "m" (__m(addr)), "0" (0))
411 
412 #define __put_user_nocheck(x, ptr, size)			\
413 ({								\
414 	int __pu_err;						\
415 	__uaccess_begin();					\
416 	__put_user_size((x), (ptr), (size), __pu_err, -EFAULT);	\
417 	__uaccess_end();					\
418 	__builtin_expect(__pu_err, 0);				\
419 })
420 
421 #define __get_user_nocheck(x, ptr, size)				\
422 ({									\
423 	int __gu_err;							\
424 	unsigned long __gu_val;						\
425 	__uaccess_begin();						\
426 	__get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);	\
427 	__uaccess_end();						\
428 	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
429 	__builtin_expect(__gu_err, 0);					\
430 })
431 
432 /* FIXME: this hack is definitely wrong -AK */
433 struct __large_struct { unsigned long buf[100]; };
434 #define __m(x) (*(struct __large_struct __user *)(x))
435 
436 /*
437  * Tell gcc we read from memory instead of writing: this is because
438  * we do not write to any memory gcc knows about, so there are no
439  * aliasing issues.
440  */
441 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
442 	asm volatile("\n"						\
443 		     "1:	mov"itype" %"rtype"1,%2\n"		\
444 		     "2:\n"						\
445 		     ".section .fixup,\"ax\"\n"				\
446 		     "3:	mov %3,%0\n"				\
447 		     "	jmp 2b\n"					\
448 		     ".previous\n"					\
449 		     _ASM_EXTABLE(1b, 3b)				\
450 		     : "=r"(err)					\
451 		     : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
452 
453 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)			\
454 	asm volatile("1:	mov"itype" %"rtype"0,%1\n"		\
455 		     "2:\n"						\
456 		     _ASM_EXTABLE_EX(1b, 2b)				\
457 		     : : ltype(x), "m" (__m(addr)))
458 
459 /*
460  * uaccess_try and catch
461  */
462 #define uaccess_try	do {						\
463 	current_thread_info()->uaccess_err = 0;				\
464 	__uaccess_begin();						\
465 	barrier();
466 
467 #define uaccess_catch(err)						\
468 	__uaccess_end();						\
469 	(err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);	\
470 } while (0)
471 
472 /**
473  * __get_user: - Get a simple variable from user space, with less checking.
474  * @x:   Variable to store result.
475  * @ptr: Source address, in user space.
476  *
477  * Context: User context only.  This function may sleep.
478  *
479  * This macro copies a single simple variable from user space to kernel
480  * space.  It supports simple types like char and int, but not larger
481  * data types like structures or arrays.
482  *
483  * @ptr must have pointer-to-simple-variable type, and the result of
484  * dereferencing @ptr must be assignable to @x without a cast.
485  *
486  * Caller must check the pointer with access_ok() before calling this
487  * function.
488  *
489  * Returns zero on success, or -EFAULT on error.
490  * On error, the variable @x is set to zero.
491  */
492 
493 #define __get_user(x, ptr)						\
494 	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
495 
496 /**
497  * __put_user: - Write a simple value into user space, with less checking.
498  * @x:   Value to copy to user space.
499  * @ptr: Destination address, in user space.
500  *
501  * Context: User context only.  This function may sleep.
502  *
503  * This macro copies a single simple value from kernel space to user
504  * space.  It supports simple types like char and int, but not larger
505  * data types like structures or arrays.
506  *
507  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
508  * to the result of dereferencing @ptr.
509  *
510  * Caller must check the pointer with access_ok() before calling this
511  * function.
512  *
513  * Returns zero on success, or -EFAULT on error.
514  */
515 
516 #define __put_user(x, ptr)						\
517 	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
518 
519 #define __get_user_unaligned __get_user
520 #define __put_user_unaligned __put_user
521 
522 /*
523  * {get|put}_user_try and catch
524  *
525  * get_user_try {
526  *	get_user_ex(...);
527  * } get_user_catch(err)
528  */
529 #define get_user_try		uaccess_try
530 #define get_user_catch(err)	uaccess_catch(err)
531 
532 #define get_user_ex(x, ptr)	do {					\
533 	unsigned long __gue_val;					\
534 	__get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));	\
535 	(x) = (__force __typeof__(*(ptr)))__gue_val;			\
536 } while (0)
537 
538 #define put_user_try		uaccess_try
539 #define put_user_catch(err)	uaccess_catch(err)
540 
541 #define put_user_ex(x, ptr)						\
542 	__put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
543 
544 extern unsigned long
545 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
546 extern __must_check long
547 strncpy_from_user(char *dst, const char __user *src, long count);
548 
549 extern __must_check long strlen_user(const char __user *str);
550 extern __must_check long strnlen_user(const char __user *str, long n);
551 
552 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
553 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
554 
555 extern void __cmpxchg_wrong_size(void)
556 	__compiletime_error("Bad argument size for cmpxchg");
557 
558 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)	\
559 ({									\
560 	int __ret = 0;							\
561 	__typeof__(ptr) __uval = (uval);				\
562 	__typeof__(*(ptr)) __old = (old);				\
563 	__typeof__(*(ptr)) __new = (new);				\
564 	__uaccess_begin();						\
565 	switch (size) {							\
566 	case 1:								\
567 	{								\
568 		asm volatile("\n"					\
569 			"1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"		\
570 			"2:\n"						\
571 			"\t.section .fixup, \"ax\"\n"			\
572 			"3:\tmov     %3, %0\n"				\
573 			"\tjmp     2b\n"				\
574 			"\t.previous\n"					\
575 			_ASM_EXTABLE(1b, 3b)				\
576 			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
577 			: "i" (-EFAULT), "q" (__new), "1" (__old)	\
578 			: "memory"					\
579 		);							\
580 		break;							\
581 	}								\
582 	case 2:								\
583 	{								\
584 		asm volatile("\n"					\
585 			"1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"		\
586 			"2:\n"						\
587 			"\t.section .fixup, \"ax\"\n"			\
588 			"3:\tmov     %3, %0\n"				\
589 			"\tjmp     2b\n"				\
590 			"\t.previous\n"					\
591 			_ASM_EXTABLE(1b, 3b)				\
592 			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
593 			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
594 			: "memory"					\
595 		);							\
596 		break;							\
597 	}								\
598 	case 4:								\
599 	{								\
600 		asm volatile("\n"					\
601 			"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"		\
602 			"2:\n"						\
603 			"\t.section .fixup, \"ax\"\n"			\
604 			"3:\tmov     %3, %0\n"				\
605 			"\tjmp     2b\n"				\
606 			"\t.previous\n"					\
607 			_ASM_EXTABLE(1b, 3b)				\
608 			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
609 			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
610 			: "memory"					\
611 		);							\
612 		break;							\
613 	}								\
614 	case 8:								\
615 	{								\
616 		if (!IS_ENABLED(CONFIG_X86_64))				\
617 			__cmpxchg_wrong_size();				\
618 									\
619 		asm volatile("\n"					\
620 			"1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"		\
621 			"2:\n"						\
622 			"\t.section .fixup, \"ax\"\n"			\
623 			"3:\tmov     %3, %0\n"				\
624 			"\tjmp     2b\n"				\
625 			"\t.previous\n"					\
626 			_ASM_EXTABLE(1b, 3b)				\
627 			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
628 			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
629 			: "memory"					\
630 		);							\
631 		break;							\
632 	}								\
633 	default:							\
634 		__cmpxchg_wrong_size();					\
635 	}								\
636 	__uaccess_end();						\
637 	*__uval = __old;						\
638 	__ret;								\
639 })
640 
641 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)		\
642 ({									\
643 	access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?		\
644 		__user_atomic_cmpxchg_inatomic((uval), (ptr),		\
645 				(old), (new), sizeof(*(ptr))) :		\
646 		-EFAULT;						\
647 })
648 
649 /*
650  * movsl can be slow when source and dest are not both 8-byte aligned
651  */
652 #ifdef CONFIG_X86_INTEL_USERCOPY
653 extern struct movsl_mask {
654 	int mask;
655 } ____cacheline_aligned_in_smp movsl_mask;
656 #endif
657 
658 #define ARCH_HAS_NOCACHE_UACCESS 1
659 
660 #ifdef CONFIG_X86_32
661 # include <asm/uaccess_32.h>
662 #else
663 # include <asm/uaccess_64.h>
664 #endif
665 
666 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
667 					   unsigned n);
668 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
669 					 unsigned n);
670 
671 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
672 # define copy_user_diag __compiletime_error
673 #else
674 # define copy_user_diag __compiletime_warning
675 #endif
676 
677 extern void copy_user_diag("copy_from_user() buffer size is too small")
678 copy_from_user_overflow(void);
679 extern void copy_user_diag("copy_to_user() buffer size is too small")
680 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
681 
682 #undef copy_user_diag
683 
684 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
685 
686 extern void
687 __compiletime_warning("copy_from_user() buffer size is not provably correct")
688 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
689 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
690 
691 extern void
692 __compiletime_warning("copy_to_user() buffer size is not provably correct")
693 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
694 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
695 
696 #else
697 
698 static inline void
__copy_from_user_overflow(int size,unsigned long count)699 __copy_from_user_overflow(int size, unsigned long count)
700 {
701 	WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
702 }
703 
704 #define __copy_to_user_overflow __copy_from_user_overflow
705 
706 #endif
707 
708 static __always_inline unsigned long __must_check
copy_from_user(void * to,const void __user * from,unsigned long n)709 copy_from_user(void *to, const void __user *from, unsigned long n)
710 {
711 	int sz = __compiletime_object_size(to);
712 
713 	might_fault();
714 
715 	/*
716 	 * While we would like to have the compiler do the checking for us
717 	 * even in the non-constant size case, any false positives there are
718 	 * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
719 	 * without - the [hopefully] dangerous looking nature of the warning
720 	 * would make people go look at the respecitive call sites over and
721 	 * over again just to find that there's no problem).
722 	 *
723 	 * And there are cases where it's just not realistic for the compiler
724 	 * to prove the count to be in range. For example when multiple call
725 	 * sites of a helper function - perhaps in different source files -
726 	 * all doing proper range checking, yet the helper function not doing
727 	 * so again.
728 	 *
729 	 * Therefore limit the compile time checking to the constant size
730 	 * case, and do only runtime checking for non-constant sizes.
731 	 */
732 
733 	if (likely(sz < 0 || sz >= n)) {
734 		check_object_size(to, n, false);
735 		n = _copy_from_user(to, from, n);
736 	} else if (__builtin_constant_p(n))
737 		copy_from_user_overflow();
738 	else
739 		__copy_from_user_overflow(sz, n);
740 
741 	return n;
742 }
743 
744 static __always_inline unsigned long __must_check
copy_to_user(void __user * to,const void * from,unsigned long n)745 copy_to_user(void __user *to, const void *from, unsigned long n)
746 {
747 	int sz = __compiletime_object_size(from);
748 
749 	might_fault();
750 
751 	/* See the comment in copy_from_user() above. */
752 	if (likely(sz < 0 || sz >= n)) {
753 		check_object_size(from, n, true);
754 		n = _copy_to_user(to, from, n);
755 	} else if (__builtin_constant_p(n))
756 		copy_to_user_overflow();
757 	else
758 		__copy_to_user_overflow(sz, n);
759 
760 	return n;
761 }
762 
763 #undef __copy_from_user_overflow
764 #undef __copy_to_user_overflow
765 
766 /*
767  * The "unsafe" user accesses aren't really "unsafe", but the naming
768  * is a big fat warning: you have to not only do the access_ok()
769  * checking before using them, but you have to surround them with the
770  * user_access_begin/end() pair.
771  */
772 #define user_access_begin()	__uaccess_begin()
773 #define user_access_end()	__uaccess_end()
774 
775 #define unsafe_put_user(x, ptr, err_label)					\
776 do {										\
777 	int __pu_err;								\
778 	__put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);		\
779 	if (unlikely(__pu_err)) goto err_label;					\
780 } while (0)
781 
782 #define unsafe_get_user(x, ptr, err_label)					\
783 do {										\
784 	int __gu_err;								\
785 	unsigned long __gu_val;							\
786 	__get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);	\
787 	(x) = (__force __typeof__(*(ptr)))__gu_val;				\
788 	if (unlikely(__gu_err)) goto err_label;					\
789 } while (0)
790 
791 #endif /* _ASM_X86_UACCESS_H */
792 
793