summaryrefslogtreecommitdiffstats
path: root/arch/riscv/include/asm/uaccess.h
blob: e076437cfafecff41edf7c6833ad60e46482430b (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
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2012 Regents of the University of California
 *
 * This file was copied from include/asm-generic/uaccess.h
 */

#ifndef _ASM_RISCV_UACCESS_H
#define _ASM_RISCV_UACCESS_H

/*
 * User space memory access functions
 */
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/thread_info.h>
#include <asm/byteorder.h>
#include <asm/extable.h>
#include <asm/asm.h>

#define __enable_user_access()							\
	__asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory")
#define __disable_user_access()							\
	__asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")

/*
 * 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(~0UL)
#define USER_DS		MAKE_MM_SEG(TASK_SIZE)

#define get_fs()	(current_thread_info()->addr_limit)

static inline void set_fs(mm_segment_t fs)
{
	current_thread_info()->addr_limit = fs;
}

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

#define user_addr_max()	(get_fs().seg)


/**
 * 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.
 *
 * 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) ({					\
	__chk_user_ptr(addr);						\
	likely(__access_ok((unsigned long __force)(addr), (size)));	\
})

/*
 * Ensure that the range [addr, addr+size) is within the process's
 * address space
 */
static inline int __access_ok(unsigned long addr, unsigned long size)
{
	const mm_segment_t fs = get_fs();

	return size <= fs.seg && addr <= fs.seg - size;
}

/*
 * 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.
 */

#define __LSW	0
#define __MSW	1

/*
 * The "__xxx" versions of the user access functions do not verify the address
 * space - it must have been done previously with a separate "access_ok()"
 * call.
 */

#define __get_user_asm(insn, x, ptr, err)			\
do {								\
	uintptr_t __tmp;					\
	__typeof__(x) __x;					\
	__enable_user_access();					\
	__asm__ __volatile__ (					\
		"1:\n"						\
		"	" insn " %1, %3\n"			\
		"2:\n"						\
		"	.section .fixup,\"ax\"\n"		\
		"	.balign 4\n"				\
		"3:\n"						\
		"	li %0, %4\n"				\
		"	li %1, 0\n"				\
		"	jump 2b, %2\n"				\
		"	.previous\n"				\
		"	.section __ex_table,\"a\"\n"		\
		"	.balign " RISCV_SZPTR "\n"			\
		"	" RISCV_PTR " 1b, 3b\n"			\
		"	.previous"				\
		: "+r" (err), "=&r" (__x), "=r" (__tmp)		\
		: "m" (*(ptr)), "i" (-EFAULT));			\
	__disable_user_access();				\
	(x) = __x;						\
} while (0)

#ifdef CONFIG_64BIT
#define __get_user_8(x, ptr, err) \
	__get_user_asm("ld", x, ptr, err)
#else /* !CONFIG_64BIT */
#define __get_user_8(x, ptr, err)				\
do {								\
	u32 __user *__ptr = (u32 __user *)(ptr);		\
	u32 __lo, __hi;						\
	uintptr_t __tmp;					\
	__enable_user_access();					\
	__asm__ __volatile__ (					\
		"1:\n"						\
		"	lw %1, %4\n"				\
		"2:\n"						\
		"	lw %2, %5\n"				\
		"3:\n"						\
		"	.section .fixup,\"ax\"\n"		\
		"	.balign 4\n"				\
		"4:\n"						\
		"	li %0, %6\n"				\
		"	li %1, 0\n"				\
		"	li %2, 0\n"				\
		"	jump 3b, %3\n"				\
		"	.previous\n"				\
		"	.section __ex_table,\"a\"\n"		\
		"	.balign " RISCV_SZPTR "\n"			\
		"	" RISCV_PTR " 1b, 4b\n"			\
		"	" RISCV_PTR " 2b, 4b\n"			\
		"	.previous"				\
		: "+r" (err), "=&r" (__lo), "=r" (__hi),	\
			"=r" (__tmp)				\
		: "m" (__ptr[__LSW]), "m" (__ptr[__MSW]),	\
			"i" (-EFAULT));				\
	__disable_user_access();				\
	(x) = (__typeof__(x))((__typeof__((x)-(x)))(		\
		(((u64)__hi << 32) | __lo)));			\
} while (0)
#endif /* CONFIG_64BIT */


/**
 * __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)					\
({								\
	register long __gu_err = 0;				\
	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);	\
	__chk_user_ptr(__gu_ptr);				\
	switch (sizeof(*__gu_ptr)) {				\
	case 1:							\
		__get_user_asm("lb", (x), __gu_ptr, __gu_err);	\
		break;						\
	case 2:							\
		__get_user_asm("lh", (x), __gu_ptr, __gu_err);	\
		break;						\
	case 4:							\
		__get_user_asm("lw", (x), __gu_ptr, __gu_err);	\
		break;						\
	case 8:							\
		__get_user_8((x), __gu_ptr, __gu_err);	\
		break;						\
	default:						\
		BUILD_BUG();					\
	}							\
	__gu_err;						\
})

/**
 * 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)					\
({								\
	const __typeof__(*(ptr)) __user *__p = (ptr);		\
	might_fault();						\
	access_ok(__p, sizeof(*__p)) ?		\
		__get_user((x), __p) :				\
		((x) = 0, -EFAULT);				\
})

#define __put_user_asm(insn, x, ptr, err)			\
do {								\
	uintptr_t __tmp;					\
	__typeof__(*(ptr)) __x = x;				\
	__enable_user_access();					\
	__asm__ __volatile__ (					\
		"1:\n"						\
		"	" insn " %z3, %2\n"			\
		"2:\n"						\
		"	.section .fixup,\"ax\"\n"		\
		"	.balign 4\n"				\
		"3:\n"						\
		"	li %0, %4\n"				\
		"	jump 2b, %1\n"				\
		"	.previous\n"				\
		"	.section __ex_table,\"a\"\n"		\
		"	.balign " RISCV_SZPTR "\n"			\
		"	" RISCV_PTR " 1b, 3b\n"			\
		"	.previous"				\
		: "+r" (err), "=r" (__tmp), "=m" (*(ptr))	\
		: "rJ" (__x), "i" (-EFAULT));			\
	__disable_user_access();				\
} while (0)

#ifdef CONFIG_64BIT
#define __put_user_8(x, ptr, err) \
	__put_user_asm("sd", x, ptr, err)
#else /* !CONFIG_64BIT */
#define __put_user_8(x, ptr, err)				\
do {								\
	u32 __user *__ptr = (u32 __user *)(ptr);		\
	u64 __x = (__typeof__((x)-(x)))(x);			\
	uintptr_t __tmp;					\
	__enable_user_access();					\
	__asm__ __volatile__ (					\
		"1:\n"						\
		"	sw %z4, %2\n"				\
		"2:\n"						\
		"	sw %z5, %3\n"				\
		"3:\n"						\
		"	.section .fixup,\"ax\"\n"		\
		"	.balign 4\n"				\
		"4:\n"						\
		"	li %0, %6\n"				\
		"	jump 3b, %1\n"				\
		"	.previous\n"				\
		"	.section __ex_table,\"a\"\n"		\
		"	.balign " RISCV_SZPTR "\n"			\
		"	" RISCV_PTR " 1b, 4b\n"			\
		"	" RISCV_PTR " 2b, 4b\n"			\
		"	.previous"				\
		: "+r" (err), "=r" (__tmp),			\
			"=m" (__ptr[__LSW]),			\
			"=m" (__ptr[__MSW])			\
		: "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT));	\
	__disable_user_access();				\
} while (0)
#endif /* CONFIG_64BIT */


/**
 * __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)					\
({								\
	register long __pu_err = 0;				\
	__typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
	__chk_user_ptr(__gu_ptr);				\
	switch (sizeof(*__gu_ptr)) {				\
	case 1:							\
		__put_user_asm("sb", (x), __gu_ptr, __pu_err);	\
		break;						\
	case 2:							\
		__put_user_asm("sh", (x), __gu_ptr, __pu_err);	\
		break;						\
	case 4:							\
		__put_user_asm("sw", (x), __gu_ptr, __pu_err);	\
		break;						\
	case 8:							\
		__put_user_8((x), __gu_ptr, __pu_err);	\
		break;						\
	default:						\
		BUILD_BUG();					\
	}							\
	__pu_err;						\
})

/**
 * 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.
 */
#define put_user(x, ptr)					\
({								\
	__typeof__(*(ptr)) __user *__p = (ptr);			\
	might_fault();						\
	access_ok(__p, sizeof(*__p)) ?		\
		__put_user((x), __p) :				\
		-EFAULT;					\
})


extern unsigned long __must_check __asm_copy_to_user(void __user *to,
	const void *from, unsigned long n);
extern unsigned long __must_check __asm_copy_from_user(void *to,
	const void __user *from, unsigned long n);

static inline unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
	return __asm_copy_from_user(to, from, n);
}

static inline unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
	return __asm_copy_to_user(to, from, n);
}

extern long strncpy_from_user(char *dest, const char __user *src, long count);

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

extern
unsigned long __must_check __clear_user(void __user *addr, unsigned long n);

static inline
unsigned long __must_check clear_user(void __user *to, unsigned long n)
{
	might_fault();
	return access_ok(to, n) ?
		__clear_user(to, n) : n;
}

/*
 * Atomic compare-and-exchange, but with a fixup for userspace faults.  Faults
 * will set "err" to -EFAULT, while successful accesses return the previous
 * value.
 */
#define __cmpxchg_user(ptr, old, new, err, size, lrb, scb)	\
({								\
	__typeof__(ptr) __ptr = (ptr);				\
	__typeof__(*(ptr)) __old = (old);			\
	__typeof__(*(ptr)) __new = (new);			\
	__typeof__(*(ptr)) __ret;				\
	__typeof__(err) __err = 0;				\
	register unsigned int __rc;				\
	__enable_user_access();					\
	switch (size) {						\
	case 4:							\
		__asm__ __volatile__ (				\
		"0:\n"						\
		"	lr.w" #scb " %[ret], %[ptr]\n"		\
		"	bne          %[ret], %z[old], 1f\n"	\
		"	sc.w" #lrb " %[rc], %z[new], %[ptr]\n"	\
		"	bnez         %[rc], 0b\n"		\
		"1:\n"						\
		".section .fixup,\"ax\"\n"			\
		".balign 4\n"					\
		"2:\n"						\
		"	li %[err], %[efault]\n"			\
		"	jump 1b, %[rc]\n"			\
		".previous\n"					\
		".section __ex_table,\"a\"\n"			\
		".balign " RISCV_SZPTR "\n"			\
		"	" RISCV_PTR " 1b, 2b\n"			\
		".previous\n"					\
			: [ret] "=&r" (__ret),			\
			  [rc]  "=&r" (__rc),			\
			  [ptr] "+A" (*__ptr),			\
			  [err] "=&r" (__err)			\
			: [old] "rJ" (__old),			\
			  [new] "rJ" (__new),			\
			  [efault] "i" (-EFAULT));		\
		break;						\
	case 8:							\
		__asm__ __volatile__ (				\
		"0:\n"						\
		"	lr.d" #scb " %[ret], %[ptr]\n"		\
		"	bne          %[ret], %z[old], 1f\n"	\
		"	sc.d" #lrb " %[rc], %z[new], %[ptr]\n"	\
		"	bnez         %[rc], 0b\n"		\
		"1:\n"						\
		".section .fixup,\"ax\"\n"			\
		".balign 4\n"					\
		"2:\n"						\
		"	li %[err], %[efault]\n"			\
		"	jump 1b, %[rc]\n"			\
		".previous\n"					\
		".section __ex_table,\"a\"\n"			\
		".balign " RISCV_SZPTR "\n"			\
		"	" RISCV_PTR " 1b, 2b\n"			\
		".previous\n"					\
			: [ret] "=&r" (__ret),			\
			  [rc]  "=&r" (__rc),			\
			  [ptr] "+A" (*__ptr),			\
			  [err] "=&r" (__err)			\
			: [old] "rJ" (__old),			\
			  [new] "rJ" (__new),			\
			  [efault] "i" (-EFAULT));		\
		break;						\
	default:						\
		BUILD_BUG();					\
	}							\
	__disable_user_access();				\
	(err) = __err;						\
	__ret;							\
})

#endif /* _ASM_RISCV_UACCESS_H */