summaryrefslogtreecommitdiff
path: root/arch/x86/include/asm/uaccess.h
blob: a77445d1b0348675b5b750ad6acd617321b49b1b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_UACCESS_H
#define _ASM_X86_UACCESS_H
/*
 * User space memory access functions
 */
#include <linux/compiler.h>
#include <linux/kasan-checks.h>
#include <linux/string.h>
#include <asm/asm.h>
#include <asm/page.h>
#include <asm/smap.h>
#include <asm/extable.h>

/*
 * The fs value determines whether argument validity checking should be
 * performed or not.  If get_fs() == USER_DS, checking is performed, with
 * get_fs() == KERNEL_DS, checking is bypassed.
 *
 * For historical reasons, these macros are grossly misnamed.
 */

#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })

#define KERNEL_DS	MAKE_MM_SEG(-1UL)
#define USER_DS 	MAKE_MM_SEG(TASK_SIZE_MAX)

#define get_ds()	(KERNEL_DS)
#define get_fs()	(current->thread.addr_limit)
static inline void set_fs(mm_segment_t fs)
{
	current->thread.addr_limit = fs;
	/* On user-mode return, check fs is correct */
	set_thread_flag(TIF_FSCHECK);
}

#define segment_eq(a, b)	((a).seg == (b).seg)

#define user_addr_max() (current->thread.addr_limit.seg)
#define __addr_ok(addr) 	\
	((unsigned long __force)(addr) < user_addr_max())

/*
 * Test whether a block of memory is a valid user space address.
 * Returns 0 if the range is valid, nonzero otherwise.
 */
static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
{
	/*
	 * If we have used "sizeof()" for the size,
	 * we know it won't overflow the limit (but
	 * it might overflow the 'addr', so it's
	 * important to subtract the size from the
	 * limit, not add it to the address).
	 */
	if (__builtin_constant_p(size))
		return unlikely(addr > limit - size);

	/* Arbitrary sizes? Be careful about overflow */
	addr += size;
	if (unlikely(addr < size))
		return true;
	return unlikely(addr > limit);
}

#define __range_not_ok(addr, size, limit)				\
({									\
	__chk_user_ptr(addr);						\
	__chk_range_not_ok((unsigned long __force)(addr), size, limit); \
})

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
# define WARN_ON_IN_IRQ()	WARN_ON_ONCE(!in_task())
#else
# define WARN_ON_IN_IRQ()
#endif

/**
 * access_ok: - Checks if a user space pointer is valid
 * @addr: User space pointer to start of block to check
 * @size: Size of block to check
 *
 * Context: User context only. This function may sleep if pagefaults are
 *          enabled.
 *
 * Checks if a pointer to a block of memory in user space is valid.
 *
 * Returns true (nonzero) if the memory block may be valid, false (zero)
 * if it is definitely invalid.
 *
 * Note that, depending on architecture, this function probably just
 * checks that the pointer is in the user space range - after calling
 * this function, memory access functions may still return -EFAULT.
 */
#define access_ok(addr, size)					\
({									\
	WARN_ON_IN_IRQ();						\
	likely(!__range_not_ok(addr, size, user_addr_max()));		\
})

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * This gets kind of ugly. We want to return _two_ values in "get_user()"
 * and yet we don't want to do any pointers, because that is too much
 * of a performance impact. Thus we have a few rather ugly macros here,
 * and hide all the ugliness from the user.
 *
 * The "__xxx" versions of the user access functions are versions that
 * do not verify the address space, that must have been done previously
 * with a separate "access_ok()" call (this is used when we do multiple
 * accesses to the same area of user memory).
 */

extern int __get_user_1(void);
extern int __get_user_2(void);
extern int __get_user_4(void);
extern int __get_user_8(void);
extern int __get_user_bad(void);

#define __uaccess_begin() stac()
#define __uaccess_end()   clac()
#define __uaccess_begin_nospec()	\
({					\
	stac();				\
	barrier_nospec();		\
})

/*
 * This is a type: either unsigned long, if the argument fits into
 * that type, or otherwise unsigned long long.
 */
#define __inttype(x) \
__typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))

/**
 * get_user: - Get a simple variable from user space.
 * @x:   Variable to store result.
 * @ptr: Source address, in user space.
 *
 * Context: User context only. This function may sleep if pagefaults are
 *          enabled.
 *
 * This macro copies a single simple variable from user space to kernel
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and the result of
 * dereferencing @ptr must be assignable to @x without a cast.
 *
 * Returns zero on success, or -EFAULT on error.
 * On error, the variable @x is set to zero.
 */
/*
 * Careful: we have to cast the result to the type of the pointer
 * for sign reasons.
 *
 * The use of _ASM_DX as the register specifier is a bit of a
 * simplification, as gcc only cares about it as the starting point
 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 * (%ecx being the next register in gcc's x86 register sequence), and
 * %rdx on 64 bits.
 *
 * Clang/LLVM cares about the size of the register, but still wants
 * the base register for something that ends up being a pair.
 */
#define get_user(x, ptr)						\
({									\
	int __ret_gu;							\
	register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);		\
	__chk_user_ptr(ptr);						\
	might_fault();							\
	asm volatile("call __get_user_%P4"				\
		     : "=a" (__ret_gu), "=r" (__val_gu),		\
			ASM_CALL_CONSTRAINT				\
		     : "0" (ptr), "i" (sizeof(*(ptr))));		\
	(x) = (__force __typeof__(*(ptr))) __val_gu;			\
	__builtin_expect(__ret_gu, 0);					\
})

#define __put_user_x(size, x, ptr, __ret_pu)			\
	asm volatile("call __put_user_" #size : "=a" (__ret_pu)	\
		     : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")



#ifdef CONFIG_X86_32
#define __put_user_goto_u64(x, addr, label)			\
	asm_volatile_goto("\n"					\
		     "1:	movl %%eax,0(%1)\n"		\
		     "2:	movl %%edx,4(%1)\n"		\
		     _ASM_EXTABLE_UA(1b, %l2)			\
		     _ASM_EXTABLE_UA(2b, %l2)			\
		     : : "A" (x), "r" (addr)			\
		     : : label)

#define __put_user_asm_ex_u64(x, addr)					\
	asm volatile("\n"						\
		     "1:	movl %%eax,0(%1)\n"			\
		     "2:	movl %%edx,4(%1)\n"			\
		     "3:"						\
		     _ASM_EXTABLE_EX(1b, 2b)				\
		     _ASM_EXTABLE_EX(2b, 3b)				\
		     : : "A" (x), "r" (addr))

#define __put_user_x8(x, ptr, __ret_pu)				\
	asm volatile("call __put_user_8" : "=a" (__ret_pu)	\
		     : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
#else
#define __put_user_goto_u64(x, ptr, label) \
	__put_user_goto(x, ptr, "q", "", "er", label)
#define __put_user_asm_ex_u64(x, addr)	\
	__put_user_asm_ex(x, addr, "q", "", "er")
#define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
#endif

extern void __put_user_bad(void);

/*
 * Strange magic calling convention: pointer in %ecx,
 * value in %eax(:%edx), return value in %eax. clobbers %rbx
 */
extern void __put_user_1(void);
extern void __put_user_2(void);
extern void __put_user_4(void);
extern void __put_user_8(void);

/**
 * put_user: - Write a simple value into user space.
 * @x:   Value to copy to user space.
 * @ptr: Destination address, in user space.
 *
 * Context: User context only. This function may sleep if pagefaults are
 *          enabled.
 *
 * This macro copies a single simple value from kernel space to user
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 * to the result of dereferencing @ptr.
 *
 * Returns zero on success, or -EFAULT on error.
 */
#define put_user(x, ptr)					\
({								\
	int __ret_pu;						\
	__typeof__(*(ptr)) __pu_val;				\
	__chk_user_ptr(ptr);					\
	might_fault();						\
	__pu_val = x;						\
	switch (sizeof(*(ptr))) {				\
	case 1:							\
		__put_user_x(1, __pu_val, ptr, __ret_pu);	\
		break;						\
	case 2:							\
		__put_user_x(2, __pu_val, ptr, __ret_pu);	\
		break;						\
	case 4:							\
		__put_user_x(4, __pu_val, ptr, __ret_pu);	\
		break;						\
	case 8:							\
		__put_user_x8(__pu_val, ptr, __ret_pu);		\
		break;						\
	default:						\
		__put_user_x(X, __pu_val, ptr, __ret_pu);	\
		break;						\
	}							\
	__builtin_expect(__ret_pu, 0);				\
})

#define __put_user_size(x, ptr, size, label)				\
do {									\
	__chk_user_ptr(ptr);						\
	switch (size) {							\
	case 1:								\
		__put_user_goto(x, ptr, "b", "b", "iq", label);	\
		break;							\
	case 2:								\
		__put_user_goto(x, ptr, "w", "w", "ir", label);		\
		break;							\
	case 4:								\
		__put_user_goto(x, ptr, "l", "k", "ir", label);		\
		break;							\
	case 8:								\
		__put_user_goto_u64((__typeof__(*ptr))(x), ptr, label);	\
		break;							\
	default:							\
		__put_user_bad();					\
	}								\
} while (0)

/*
 * This doesn't do __uaccess_begin/end - the exception handling
 * around it must do that.
 */
#define __put_user_size_ex(x, ptr, size)				\
do {									\
	__chk_user_ptr(ptr);						\
	switch (size) {							\
	case 1:								\
		__put_user_asm_ex(x, ptr, "b", "b", "iq");		\
		break;							\
	case 2:								\
		__put_user_asm_ex(x, ptr, "w", "w", "ir");		\
		break;							\
	case 4:								\
		__put_user_asm_ex(x, ptr, "l", "k", "ir");		\
		break;							\
	case 8:								\
		__put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);	\
		break;							\
	default:							\
		__put_user_bad();					\
	}								\
} while (0)

#ifdef CONFIG_X86_32
#define __get_user_asm_u64(x, ptr, retval, errret)			\
({									\
	__typeof__(ptr) __ptr = (ptr);					\
	asm volatile("\n"					\
		     "1:	movl %2,%%eax\n"			\
		     "2:	movl %3,%%edx\n"			\
		     "3:\n"				\
		     ".section .fixup,\"ax\"\n"				\
		     "4:	mov %4,%0\n"				\
		     "	xorl %%eax,%%eax\n"				\
		     "	xorl %%edx,%%edx\n"				\
		     "	jmp 3b\n"					\
		     ".previous\n"					\
		     _ASM_EXTABLE_UA(1b, 4b)				\
		     _ASM_EXTABLE_UA(2b, 4b)				\
		     : "=r" (retval), "=&A"(x)				\
		     : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),	\
		       "i" (errret), "0" (retval));			\
})

#define __get_user_asm_ex_u64(x, ptr)			(x) = __get_user_bad()
#else
#define __get_user_asm_u64(x, ptr, retval, errret) \
	 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
#define __get_user_asm_ex_u64(x, ptr) \
	 __get_user_asm_ex(x, ptr, "q", "", "=r")
#endif

#define __get_user_size(x, ptr, size, retval, errret)			\
do {									\
	retval = 0;							\
	__chk_user_ptr(ptr);						\
	switch (size) {							\
	case 1:								\
		__get_user_asm(x, ptr, retval, "b", "b", "=q", errret);	\
		break;							\
	case 2:								\
		__get_user_asm(x, ptr, retval, "w", "w", "=r", errret);	\
		break;							\
	case 4:								\
		__get_user_asm(x, ptr, retval, "l", "k", "=r", errret);	\
		break;							\
	case 8:								\
		__get_user_asm_u64(x, ptr, retval, errret);		\
		break;							\
	default:							\
		(x) = __get_user_bad();					\
	}								\
} while (0)

#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
	asm volatile("\n"						\
		     "1:	mov"itype" %2,%"rtype"1\n"		\
		     "2:\n"						\
		     ".section .fixup,\"ax\"\n"				\
		     "3:	mov %3,%0\n"				\
		     "	xor"itype" %"rtype"1,%"rtype"1\n"		\
		     "	jmp 2b\n"					\
		     ".previous\n"					\
		     _ASM_EXTABLE_UA(1b, 3b)				\
		     : "=r" (err), ltype(x)				\
		     : "m" (__m(addr)), "i" (errret), "0" (err))

#define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)	\
	asm volatile("\n"						\
		     "1:	mov"itype" %2,%"rtype"1\n"		\
		     "2:\n"						\
		     ".section .fixup,\"ax\"\n"				\
		     "3:	mov %3,%0\n"				\
		     "	jmp 2b\n"					\
		     ".previous\n"					\
		     _ASM_EXTABLE_UA(1b, 3b)				\
		     : "=r" (err), ltype(x)				\
		     : "m" (__m(addr)), "i" (errret), "0" (err))

/*
 * This doesn't do __uaccess_begin/end - the exception handling
 * around it must do that.
 */
#define __get_user_size_ex(x, ptr, size)				\
do {									\
	__chk_user_ptr(ptr);						\
	switch (size) {							\
	case 1:								\
		__get_user_asm_ex(x, ptr, "b", "b", "=q");		\
		break;							\
	case 2:								\
		__get_user_asm_ex(x, ptr, "w", "w", "=r");		\
		break;							\
	case 4:								\
		__get_user_asm_ex(x, ptr, "l", "k", "=r");		\
		break;							\
	case 8:								\
		__get_user_asm_ex_u64(x, ptr);				\
		break;							\
	default:							\
		(x) = __get_user_bad();					\
	}								\
} while (0)

#define __get_user_asm_ex(x, addr, itype, rtype, ltype)			\
	asm volatile("1:	mov"itype" %1,%"rtype"0\n"		\
		     "2:\n"						\
		     ".section .fixup,\"ax\"\n"				\
                     "3:xor"itype" %"rtype"0,%"rtype"0\n"		\
		     "  jmp 2b\n"					\
		     ".previous\n"					\
		     _ASM_EXTABLE_EX(1b, 3b)				\
		     : ltype(x) : "m" (__m(addr)))

#define __put_user_nocheck(x, ptr, size)			\
({								\
	__label__ __pu_label;					\
	int __pu_err = -EFAULT;					\
	__uaccess_begin();					\
	__put_user_size((x), (ptr), (size), __pu_label);	\
	__pu_err = 0;						\
__pu_label:							\
	__uaccess_end();					\
	__builtin_expect(__pu_err, 0);				\
})

#define __get_user_nocheck(x, ptr, size)				\
({									\
	int __gu_err;							\
	__inttype(*(ptr)) __gu_val;					\
	__uaccess_begin_nospec();					\
	__get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);	\
	__uaccess_end();						\
	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
	__builtin_expect(__gu_err, 0);					\
})

/* FIXME: this hack is definitely wrong -AK */
struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct __user *)(x))

/*
 * Tell gcc we read from memory instead of writing: this is because
 * we do not write to any memory gcc knows about, so there are no
 * aliasing issues.
 */
#define __put_user_goto(x, addr, itype, rtype, ltype, label)	\
	asm_volatile_goto("\n"						\
		"1:	mov"itype" %"rtype"0,%1\n"			\
		_ASM_EXTABLE_UA(1b, %l2)					\
		: : ltype(x), "m" (__m(addr))				\
		: : label)

#define __put_user_failed(x, addr, itype, rtype, ltype, errret)		\
	({	__label__ __puflab;					\
		int __pufret = errret;					\
		__put_user_goto(x,addr,itype,rtype,ltype,__puflab);	\
		__pufret = 0;						\
	__puflab: __pufret; })

#define __put_user_asm(x, addr, retval, itype, rtype, ltype, errret)	do {	\
	retval = __put_user_failed(x, addr, itype, rtype, ltype, errret);	\
} while (0)

#define __put_user_asm_ex(x, addr, itype, rtype, ltype)			\
	asm volatile("1:	mov"itype" %"rtype"0,%1\n"		\
		     "2:\n"						\
		     _ASM_EXTABLE_EX(1b, 2b)				\
		     : : ltype(x), "m" (__m(addr)))

/*
 * uaccess_try and catch
 */
#define uaccess_try	do {						\
	current->thread.uaccess_err = 0;				\
	__uaccess_begin();						\
	barrier();

#define uaccess_try_nospec do {						\
	current->thread.uaccess_err = 0;				\
	__uaccess_begin_nospec();					\

#define uaccess_catch(err)						\
	__uaccess_end();						\
	(err) |= (current->thread.uaccess_err ? -EFAULT : 0);		\
} while (0)

/**
 * __get_user: - Get a simple variable from user space, with less checking.
 * @x:   Variable to store result.
 * @ptr: Source address, in user space.
 *
 * Context: User context only. This function may sleep if pagefaults are
 *          enabled.
 *
 * This macro copies a single simple variable from user space to kernel
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and the result of
 * dereferencing @ptr must be assignable to @x without a cast.
 *
 * Caller must check the pointer with access_ok() before calling this
 * function.
 *
 * Returns zero on success, or -EFAULT on error.
 * On error, the variable @x is set to zero.
 */

#define __get_user(x, ptr)						\
	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))

/**
 * __put_user: - Write a simple value into user space, with less checking.
 * @x:   Value to copy to user space.
 * @ptr: Destination address, in user space.
 *
 * Context: User context only. This function may sleep if pagefaults are
 *          enabled.
 *
 * This macro copies a single simple value from kernel space to user
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 * to the result of dereferencing @ptr.
 *
 * Caller must check the pointer with access_ok() before calling this
 * function.
 *
 * Returns zero on success, or -EFAULT on error.
 */

#define __put_user(x, ptr)						\
	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))

/*
 * {get|put}_user_try and catch
 *
 * get_user_try {
 *	get_user_ex(...);
 * } get_user_catch(err)
 */
#define get_user_try		uaccess_try_nospec
#define get_user_catch(err)	uaccess_catch(err)

#define get_user_ex(x, ptr)	do {					\
	unsigned long __gue_val;					\
	__get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));	\
	(x) = (__force __typeof__(*(ptr)))__gue_val;			\
} while (0)

#define put_user_try		uaccess_try
#define put_user_catch(err)	uaccess_catch(err)

#define put_user_ex(x, ptr)						\
	__put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))

extern unsigned long
copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
extern __must_check long
strncpy_from_user(char *dst, const char __user *src, long count);

extern __must_check long strnlen_user(const char __user *str, long n);

unsigned long __must_check clear_user(void __user *mem, unsigned long len);
unsigned long __must_check __clear_user(void __user *mem, unsigned long len);

extern void __cmpxchg_wrong_size(void)
	__compiletime_error("Bad argument size for cmpxchg");

#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)	\
({									\
	int __ret = 0;							\
	__typeof__(ptr) __uval = (uval);				\
	__typeof__(*(ptr)) __old = (old);				\
	__typeof__(*(ptr)) __new = (new);				\
	__uaccess_begin_nospec();					\
	switch (size) {							\
	case 1:								\
	{								\
		asm volatile("\n"					\
			"1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"		\
			"2:\n"						\
			"\t.section .fixup, \"ax\"\n"			\
			"3:\tmov     %3, %0\n"				\
			"\tjmp     2b\n"				\
			"\t.previous\n"					\
			_ASM_EXTABLE_UA(1b, 3b)				\
			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
			: "i" (-EFAULT), "q" (__new), "1" (__old)	\
			: "memory"					\
		);							\
		break;							\
	}								\
	case 2:								\
	{								\
		asm volatile("\n"					\
			"1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"		\
			"2:\n"						\
			"\t.section .fixup, \"ax\"\n"			\
			"3:\tmov     %3, %0\n"				\
			"\tjmp     2b\n"				\
			"\t.previous\n"					\
			_ASM_EXTABLE_UA(1b, 3b)				\
			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
			: "memory"					\
		);							\
		break;							\
	}								\
	case 4:								\
	{								\
		asm volatile("\n"					\
			"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"		\
			"2:\n"						\
			"\t.section .fixup, \"ax\"\n"			\
			"3:\tmov     %3, %0\n"				\
			"\tjmp     2b\n"				\
			"\t.previous\n"					\
			_ASM_EXTABLE_UA(1b, 3b)				\
			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
			: "memory"					\
		);							\
		break;							\
	}								\
	case 8:								\
	{								\
		if (!IS_ENABLED(CONFIG_X86_64))				\
			__cmpxchg_wrong_size();				\
									\
		asm volatile("\n"					\
			"1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"		\
			"2:\n"						\
			"\t.section .fixup, \"ax\"\n"			\
			"3:\tmov     %3, %0\n"				\
			"\tjmp     2b\n"				\
			"\t.previous\n"					\
			_ASM_EXTABLE_UA(1b, 3b)				\
			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
			: "memory"					\
		);							\
		break;							\
	}								\
	default:							\
		__cmpxchg_wrong_size();					\
	}								\
	__uaccess_end();						\
	*__uval = __old;						\
	__ret;								\
})

#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)		\
({									\
	access_ok((ptr), sizeof(*(ptr))) ?		\
		__user_atomic_cmpxchg_inatomic((uval), (ptr),		\
				(old), (new), sizeof(*(ptr))) :		\
		-EFAULT;						\
})

/*
 * movsl can be slow when source and dest are not both 8-byte aligned
 */
#ifdef CONFIG_X86_INTEL_USERCOPY
extern struct movsl_mask {
	int mask;
} ____cacheline_aligned_in_smp movsl_mask;
#endif

#define ARCH_HAS_NOCACHE_UACCESS 1

#ifdef CONFIG_X86_32
# include <asm/uaccess_32.h>
#else
# include <asm/uaccess_64.h>
#endif

/*
 * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 * nested NMI paths are careful to preserve CR2.
 *
 * Caller must use pagefault_enable/disable, or run in interrupt context,
 * and also do a uaccess_ok() check
 */
#define __copy_from_user_nmi __copy_from_user_inatomic

/*
 * The "unsafe" user accesses aren't really "unsafe", but the naming
 * is a big fat warning: you have to not only do the access_ok()
 * checking before using them, but you have to surround them with the
 * user_access_begin/end() pair.
 */
static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
{
	if (unlikely(!access_ok(ptr,len)))
		return 0;
	__uaccess_begin();
	return 1;
}
#define user_access_begin(a,b)	user_access_begin(a,b)
#define user_access_end()	__uaccess_end()

#define unsafe_put_user(x, ptr, label)	\
	__put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)

#define unsafe_get_user(x, ptr, err_label)					\
do {										\
	int __gu_err;								\
	__inttype(*(ptr)) __gu_val;						\
	__get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);	\
	(x) = (__force __typeof__(*(ptr)))__gu_val;				\
	if (unlikely(__gu_err)) goto err_label;					\
} while (0)

#endif /* _ASM_X86_UACCESS_H */