1/*
2 * User space memory access functions for Nios II
3 *
4 * Copyright (C) 2010-2011, Tobias Klauser <tklauser@distanz.ch>
5 * Copyright (C) 2009, Wind River Systems Inc
6 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
7 *
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License.  See the file "COPYING" in the main directory of this archive
10 * for more details.
11 */
12
13#ifndef _ASM_NIOS2_UACCESS_H
14#define _ASM_NIOS2_UACCESS_H
15
16#include <linux/errno.h>
17#include <linux/thread_info.h>
18#include <linux/string.h>
19
20#include <asm/page.h>
21
22#define VERIFY_READ	0
23#define VERIFY_WRITE	1
24
25/*
26 * The exception table consists of pairs of addresses: the first is the
27 * address of an instruction that is allowed to fault, and the second is
28 * the address at which the program should continue.  No registers are
29 * modified, so it is entirely up to the continuation code to figure out
30 * what to do.
31 *
32 * All the routines below use bits of fixup code that are out of line
33 * with the main instruction path.  This means when everything is well,
34 * we don't even have to jump over them.  Further, they do not intrude
35 * on our cache or tlb entries.
36 */
37struct exception_table_entry {
38	unsigned long insn;
39	unsigned long fixup;
40};
41
42extern int fixup_exception(struct pt_regs *regs);
43
44/*
45 * Segment stuff
46 */
47#define MAKE_MM_SEG(s)		((mm_segment_t) { (s) })
48#define USER_DS			MAKE_MM_SEG(0x80000000UL)
49#define KERNEL_DS		MAKE_MM_SEG(0)
50
51#define get_ds()		(KERNEL_DS)
52
53#define get_fs()		(current_thread_info()->addr_limit)
54#define set_fs(seg)		(current_thread_info()->addr_limit = (seg))
55
56#define segment_eq(a, b)	((a).seg == (b).seg)
57
58#define __access_ok(addr, len)			\
59	(((signed long)(((long)get_fs().seg) &	\
60		((long)(addr) | (((long)(addr)) + (len)) | (len)))) == 0)
61
62#define access_ok(type, addr, len)		\
63	likely(__access_ok((unsigned long)(addr), (unsigned long)(len)))
64
65# define __EX_TABLE_SECTION	".section __ex_table,\"a\"\n"
66
67/*
68 * Zero Userspace
69 */
70
71static inline unsigned long __must_check __clear_user(void __user *to,
72						      unsigned long n)
73{
74	__asm__ __volatile__ (
75		"1:     stb     zero, 0(%1)\n"
76		"       addi    %0, %0, -1\n"
77		"       addi    %1, %1, 1\n"
78		"       bne     %0, zero, 1b\n"
79		"2:\n"
80		__EX_TABLE_SECTION
81		".word  1b, 2b\n"
82		".previous\n"
83		: "=r" (n), "=r" (to)
84		: "0" (n), "1" (to)
85	);
86
87	return n;
88}
89
90static inline unsigned long __must_check clear_user(void __user *to,
91						    unsigned long n)
92{
93	if (!access_ok(VERIFY_WRITE, to, n))
94		return n;
95	return __clear_user(to, n);
96}
97
98extern long __copy_from_user(void *to, const void __user *from,
99				unsigned long n);
100extern long __copy_to_user(void __user *to, const void *from, unsigned long n);
101
102static inline long copy_from_user(void *to, const void __user *from,
103				unsigned long n)
104{
105	if (!access_ok(VERIFY_READ, from, n))
106		return n;
107	return __copy_from_user(to, from, n);
108}
109
110static inline long copy_to_user(void __user *to, const void *from,
111				unsigned long n)
112{
113	if (!access_ok(VERIFY_WRITE, to, n))
114		return n;
115	return __copy_to_user(to, from, n);
116}
117
118extern long strncpy_from_user(char *__to, const char __user *__from,
119				long __len);
120extern long strnlen_user(const char __user *s, long n);
121
122#define __copy_from_user_inatomic	__copy_from_user
123#define __copy_to_user_inatomic		__copy_to_user
124
125/* Optimized macros */
126#define __get_user_asm(val, insn, addr, err)				\
127{									\
128	__asm__ __volatile__(						\
129	"       movi    %0, %3\n"					\
130	"1:   " insn " %1, 0(%2)\n"					\
131	"       movi     %0, 0\n"					\
132	"2:\n"								\
133	"       .section __ex_table,\"a\"\n"				\
134	"       .word 1b, 2b\n"						\
135	"       .previous"						\
136	: "=&r" (err), "=r" (val)					\
137	: "r" (addr), "i" (-EFAULT));					\
138}
139
140#define __get_user_unknown(val, size, ptr, err) do {			\
141	err = 0;							\
142	if (copy_from_user(&(val), ptr, size)) {			\
143		err = -EFAULT;						\
144	}								\
145	} while (0)
146
147#define __get_user_common(val, size, ptr, err)				\
148do {									\
149	switch (size) {							\
150	case 1:								\
151		__get_user_asm(val, "ldbu", ptr, err);			\
152		break;							\
153	case 2:								\
154		__get_user_asm(val, "ldhu", ptr, err);			\
155		break;							\
156	case 4:								\
157		__get_user_asm(val, "ldw", ptr, err);			\
158		break;							\
159	default:							\
160		__get_user_unknown(val, size, ptr, err);		\
161		break;							\
162	}								\
163} while (0)
164
165#define __get_user(x, ptr)						\
166	({								\
167	long __gu_err = -EFAULT;					\
168	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
169	unsigned long __gu_val;						\
170	__get_user_common(__gu_val, sizeof(*(ptr)), __gu_ptr, __gu_err);\
171	(x) = (__force __typeof__(x))__gu_val;				\
172	__gu_err;							\
173	})
174
175#define get_user(x, ptr)						\
176({									\
177	long __gu_err = -EFAULT;					\
178	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
179	unsigned long __gu_val = 0;					\
180	if (access_ok(VERIFY_READ,  __gu_ptr, sizeof(*__gu_ptr)))	\
181		__get_user_common(__gu_val, sizeof(*__gu_ptr),		\
182			__gu_ptr, __gu_err);				\
183	(x) = (__force __typeof__(x))__gu_val;				\
184	__gu_err;							\
185})
186
187#define __put_user_asm(val, insn, ptr, err)				\
188{									\
189	__asm__ __volatile__(						\
190	"       movi    %0, %3\n"					\
191	"1:   " insn " %1, 0(%2)\n"					\
192	"       movi     %0, 0\n"					\
193	"2:\n"								\
194	"       .section __ex_table,\"a\"\n"				\
195	"       .word 1b, 2b\n"						\
196	"       .previous\n"						\
197	: "=&r" (err)							\
198	: "r" (val), "r" (ptr), "i" (-EFAULT));				\
199}
200
201#define put_user(x, ptr)						\
202({									\
203	long __pu_err = -EFAULT;					\
204	__typeof__(*(ptr)) __user *__pu_ptr = (ptr);			\
205	__typeof__(*(ptr)) __pu_val = (__typeof(*ptr))(x);		\
206	if (access_ok(VERIFY_WRITE, __pu_ptr, sizeof(*__pu_ptr))) {	\
207		switch (sizeof(*__pu_ptr)) {				\
208		case 1:							\
209			__put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err); \
210			break;						\
211		case 2:							\
212			__put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err); \
213			break;						\
214		case 4:							\
215			__put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err); \
216			break;						\
217		default:						\
218			/* XXX: This looks wrong... */			\
219			__pu_err = 0;					\
220			if (copy_to_user(__pu_ptr, &(__pu_val),		\
221				sizeof(*__pu_ptr)))			\
222				__pu_err = -EFAULT;			\
223			break;						\
224		}							\
225	}								\
226	__pu_err;							\
227})
228
229#define __put_user(x, ptr) put_user(x, ptr)
230
231#endif /* _ASM_NIOS2_UACCESS_H */
232