aboutsummaryrefslogtreecommitdiffstats
path: root/include/asm-i386/uaccess.h
blob: d2a4f7be9c2c5ee3a1516b0b5bf636addc2cefac (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
#ifndef __i386_UACCESS_H
#define __i386_UACCESS_H

/*
 * User space memory access functions
 */
#include <linux/errno.h>
#include <linux/thread_info.h>
#include <linux/prefetch.h>
#include <linux/string.h>
#include <asm/page.h>

#define VERIFY_READ 0
#define VERIFY_WRITE 1

/*
 * 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(0xFFFFFFFFUL)
#define USER_DS		MAKE_MM_SEG(PAGE_OFFSET)

#define get_ds()	(KERNEL_DS)
#define get_fs()	(current_thread_info()->addr_limit)
#define set_fs(x)	(current_thread_info()->addr_limit = (x))

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

/*
 * 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 __addr_ok(addr) ((unsigned long __force)(addr) < (current_thread_info()->addr_limit.seg))

/*
 * Test whether a block of memory is a valid user space address.
 * Returns 0 if the range is valid, nonzero otherwise.
 *
 * This is equivalent to the following test:
 * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
 *
 * This needs 33-bit arithmetic. We have a carry...
 */
#define __range_ok(addr,size) ({ \
	unsigned long flag,roksum; \
	__chk_user_ptr(addr); \
	asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
		:"=&r" (flag), "=r" (roksum) \
		:"1" (addr),"g" ((int)(size)),"rm" (current_thread_info()->addr_limit.seg)); \
	flag; })

/**
 * access_ok: - Checks if a user space pointer is valid
 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
 *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
 *        to write to a block, it is always safe to read from it.
 * @addr: User space pointer to start of block to check
 * @size: Size of block to check
 *
 * Context: User context only.  This function may sleep.
 *
 * 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(type,addr,size) (likely(__range_ok(addr,size) == 0))

/*
 * The exception table consists of pairs of addresses: the first is the
 * address of an instruction that is allowed to fault, and the second is
 * the address at which the program should continue.  No registers are
 * modified, so it is entirely up to the continuation code to figure out
 * what to do.
 *
 * All the routines below use bits of fixup code that are out of line
 * with the main instruction path.  This means when everything is well,
 * we don't even have to jump over them.  Further, they do not intrude
 * on our cache or tlb entries.
 */

struct exception_table_entry
{
	unsigned long insn, fixup;
};

extern int fixup_exception(struct pt_regs *regs);

/*
 * 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 void __get_user_1(void);
extern void __get_user_2(void);
extern void __get_user_4(void);

#define __get_user_x(size,ret,x,ptr) \
	__asm__ __volatile__("call __get_user_" #size \
		:"=a" (ret),"=d" (x) \
		:"0" (ptr))


/* Careful: we have to cast the result to the type of the pointer for sign reasons */
/**
 * 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.
 *
 * 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.
 */
#define get_user(x,ptr)							\
({	int __ret_gu;							\
	unsigned long __val_gu;						\
	__chk_user_ptr(ptr);						\
	switch(sizeof (*(ptr))) {					\
	case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;		\
	case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;		\
	case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;		\
	default: __get_user_x(X,__ret_gu,__val_gu,ptr); break;		\
	}								\
	(x) = (__typeof__(*(ptr)))__val_gu;				\
	__ret_gu;							\
})

extern void __put_user_bad(void);

/*
 * Strange magic calling convention: pointer in %ecx,
 * value in %eax(:%edx), return value in %eax, no clobbers.
 */
extern void __put_user_1(void);
extern void __put_user_2(void);
extern void __put_user_4(void);
extern void __put_user_8(void);

#define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu):"A" ((typeof(*(ptr)))(x)), "c" (ptr))
#define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a" (__ret_pu):"c" (ptr))

/**
 * 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.
 *
 * 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.
 */
#ifdef CONFIG_X86_WP_WORKS_OK

#define put_user(x,ptr)						\
({	int __ret_pu;						\
	__typeof__(*(ptr)) __pu_val;				\
	__chk_user_ptr(ptr);					\
	__pu_val = x;						\
	switch(sizeof(*(ptr))) {				\
	case 1: __put_user_1(__pu_val, ptr); break;		\
	case 2: __put_user_2(__pu_val, ptr); break;		\
	case 4: __put_user_4(__pu_val, ptr); break;		\
	case 8: __put_user_8(__pu_val, ptr); break;		\
	default:__put_user_X(__pu_val, ptr); break;		\
	}							\
	__ret_pu;						\
})

#else
#define put_user(x,ptr)						\
({								\
 	int __ret_pu;						\
	__typeof__(*(ptr)) __pus_tmp = x;			\
	__ret_pu=0;						\
	if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp,		\
				sizeof(*(ptr))) != 0))		\
 		__ret_pu=-EFAULT;				\
 	__ret_pu;						\
 })


#endif

/**
 * __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.
 *
 * 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.
 *
 * 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)))

#define __put_user_nocheck(x,ptr,size)				\
({								\
	long __pu_err;						\
	__put_user_size((x),(ptr),(size),__pu_err,-EFAULT);	\
	__pu_err;						\
})


#define __put_user_u64(x, addr, err)				\
	__asm__ __volatile__(					\
		"1:	movl %%eax,0(%2)\n"			\
		"2:	movl %%edx,4(%2)\n"			\
		"3:\n"						\
		".section .fixup,\"ax\"\n"			\
		"4:	movl %3,%0\n"				\
		"	jmp 3b\n"				\
		".previous\n"					\
		".section __ex_table,\"a\"\n"			\
		"	.align 4\n"				\
		"	.long 1b,4b\n"				\
		"	.long 2b,4b\n"				\
		".previous"					\
		: "=r"(err)					\
		: "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))

#ifdef CONFIG_X86_WP_WORKS_OK

#define __put_user_size(x,ptr,size,retval,errret)			\
do {									\
	retval = 0;							\
	__chk_user_ptr(ptr);						\
	switch (size) {							\
	case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break;	\
	case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
	case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break;	\
	case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
	  default: __put_user_bad();					\
	}								\
} while (0)

#else

#define __put_user_size(x,ptr,size,retval,errret)			\
do {									\
	__typeof__(*(ptr)) __pus_tmp = x;				\
	retval = 0;							\
									\
	if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))	\
		retval = errret;					\
} while (0)

#endif
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_asm(x, addr, err, itype, rtype, ltype, errret)	\
	__asm__ __volatile__(						\
		"1:	mov"itype" %"rtype"1,%2\n"			\
		"2:\n"							\
		".section .fixup,\"ax\"\n"				\
		"3:	movl %3,%0\n"					\
		"	jmp 2b\n"					\
		".previous\n"						\
		".section __ex_table,\"a\"\n"				\
		"	.align 4\n"					\
		"	.long 1b,3b\n"					\
		".previous"						\
		: "=r"(err)						\
		: ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))


#define __get_user_nocheck(x,ptr,size)				\
({								\
	long __gu_err;						\
	unsigned long __gu_val;					\
	__get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
	(x) = (__typeof__(*(ptr)))__gu_val;			\
	__gu_err;						\
})

extern long __get_user_bad(void);

#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","","=r",errret);break;	\
	default: (x) = __get_user_bad();				\
	}								\
} while (0)

#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
	__asm__ __volatile__(						\
		"1:	mov"itype" %2,%"rtype"1\n"			\
		"2:\n"							\
		".section .fixup,\"ax\"\n"				\
		"3:	movl %3,%0\n"					\
		"	xor"itype" %"rtype"1,%"rtype"1\n"		\
		"	jmp 2b\n"					\
		".previous\n"						\
		".section __ex_table,\"a\"\n"				\
		"	.align 4\n"					\
		"	.long 1b,3b\n"					\
		".previous"						\
		: "=r"(err), ltype (x)					\
		: "m"(__m(addr)), "i"(errret), "0"(err))


unsigned long __must_check __copy_to_user_ll(void __user *to,
				const void *from, unsigned long n);
unsigned long __must_check __copy_from_user_ll(void *to,
				const void __user *from, unsigned long n);
unsigned long __must_check __copy_from_user_ll_nozero(void *to,
				const void __user *from, unsigned long n);
unsigned long __must_check __copy_from_user_ll_nocache(void *to,
				const void __user *from, unsigned long n);
unsigned long __must_check __copy_from_user_ll_nocache_nozero(void *to,
				const void __user *from, unsigned long n);

/**
 * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
 * @to:   Destination address, in user space.
 * @from: Source address, in kernel space.
 * @n:    Number of bytes to copy.
 *
 * Context: User context only.
 *
 * Copy data from kernel space to user space.  Caller must check
 * the specified block with access_ok() before calling this function.
 * The caller should also make sure he pins the user space address
 * so that the we don't result in page fault and sleep.
 *
 * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 * If a store crosses a page boundary and gets a fault, the x86 will not write
 * anything, so this is accurate.
 */

static __always_inline unsigned long __must_check
__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
{
	if (__builtin_constant_p(n)) {
		unsigned long ret;

		switch (n) {
		case 1:
			__put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
			return ret;
		case 2:
			__put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
			return ret;
		case 4:
			__put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
			return ret;
		}
	}
	return __copy_to_user_ll(to, from, n);
}

/**
 * __copy_to_user: - Copy a block of data into user space, with less checking.
 * @to:   Destination address, in user space.
 * @from: Source address, in kernel space.
 * @n:    Number of bytes to copy.
 *
 * Context: User context only.  This function may sleep.
 *
 * Copy data from kernel space to user space.  Caller must check
 * the specified block with access_ok() before calling this function.
 *
 * Returns number of bytes that could not be copied.
 * On success, this will be zero.
 */
static __always_inline unsigned long __must_check
__copy_to_user(void __user *to, const void *from, unsigned long n)
{
       might_sleep();
       return __copy_to_user_inatomic(to, from, n);
}

static __always_inline unsigned long
__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
{
	/* Avoid zeroing the tail if the copy fails..
	 * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
	 * but as the zeroing behaviour is only significant when n is not
	 * constant, that shouldn't be a problem.
	 */
	if (__builtin_constant_p(n)) {
		unsigned long ret;

		switch (n) {
		case 1:
			__get_user_size(*(u8 *)to, from, 1, ret, 1);
			return ret;
		case 2:
			__get_user_size(*(u16 *)to, from, 2, ret, 2);
			return ret;
		case 4:
			__get_user_size(*(u32 *)to, from, 4, ret, 4);
			return ret;
		}
	}
	return __copy_from_user_ll_nozero(to, from, n);
}

/**
 * __copy_from_user: - Copy a block of data from user space, with less checking.
 * @to:   Destination address, in kernel space.
 * @from: Source address, in user space.
 * @n:    Number of bytes to copy.
 *
 * Context: User context only.  This function may sleep.
 *
 * Copy data from user space to kernel space.  Caller must check
 * the specified block with access_ok() before calling this function.
 *
 * Returns number of bytes that could not be copied.
 * On success, this will be zero.
 *
 * If some data could not be copied, this function will pad the copied
 * data to the requested size using zero bytes.
 *
 * An alternate version - __copy_from_user_inatomic() - may be called from
 * atomic context and will fail rather than sleep.  In this case the
 * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 * for explanation of why this is needed.
 */
static __always_inline unsigned long
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
	might_sleep();
	if (__builtin_constant_p(n)) {
		unsigned long ret;

		switch (n) {
		case 1:
			__get_user_size(*(u8 *)to, from, 1, ret, 1);
			return ret;
		case 2:
			__get_user_size(*(u16 *)to, from, 2, ret, 2);
			return ret;
		case 4:
			__get_user_size(*(u32 *)to, from, 4, ret, 4);
			return ret;
		}
	}
	return __copy_from_user_ll(to, from, n);
}

#define ARCH_HAS_NOCACHE_UACCESS

static __always_inline unsigned long __copy_from_user_nocache(void *to,
				const void __user *from, unsigned long n)
{
	might_sleep();
	if (__builtin_constant_p(n)) {
		unsigned long ret;

		switch (n) {
		case 1:
			__get_user_size(*(u8 *)to, from, 1, ret, 1);
			return ret;
		case 2:
			__get_user_size(*(u16 *)to, from, 2, ret, 2);
			return ret;
		case 4:
			__get_user_size(*(u32 *)to, from, 4, ret, 4);
			return ret;
		}
	}
	return __copy_from_user_ll_nocache(to, from, n);
}

static __always_inline unsigned long
__copy_from_user_inatomic_nocache(void *to, const void __user *from, unsigned long n)
{
       return __copy_from_user_ll_nocache_nozero(to, from, n);
}

unsigned long __must_check copy_to_user(void __user *to,
				const void *from, unsigned long n);
unsigned long __must_check copy_from_user(void *to,
				const void __user *from, unsigned long n);
long __must_check strncpy_from_user(char *dst, const char __user *src,
				long count);
long __must_check __strncpy_from_user(char *dst,
				const char __user *src, long count);

/**
 * strlen_user: - Get the size of a string in user space.
 * @str: The string to measure.
 *
 * Context: User context only.  This function may sleep.
 *
 * Get the size of a NUL-terminated string in user space.
 *
 * Returns the size of the string INCLUDING the terminating NUL.
 * On exception, returns 0.
 *
 * If there is a limit on the length of a valid string, you may wish to
 * consider using strnlen_user() instead.
 */
#define strlen_user(str) strnlen_user(str, LONG_MAX)

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);

#endif /* __i386_UACCESS_H */