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ca233862 GC |
1 | #ifndef _ASM_UACCES_H_ |
2 | #define _ASM_UACCES_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/prefetch.h> | |
10 | #include <linux/string.h> | |
11 | #include <asm/asm.h> | |
12 | #include <asm/page.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(PAGE_OFFSET) | |
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 | /* | |
37 | * Test whether a block of memory is a valid user space address. | |
38 | * Returns 0 if the range is valid, nonzero otherwise. | |
39 | * | |
40 | * This is equivalent to the following test: | |
41 | * (u33)addr + (u33)size >= (u33)current->addr_limit.seg (u65 for x86_64) | |
42 | * | |
43 | * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry... | |
44 | */ | |
45 | ||
46 | #define __range_not_ok(addr, size) \ | |
47 | ({ \ | |
48 | unsigned long flag, roksum; \ | |
49 | __chk_user_ptr(addr); \ | |
50 | asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0" \ | |
51 | : "=&r" (flag), "=r" (roksum) \ | |
52 | : "1" (addr), "g" ((long)(size)), \ | |
53 | "rm" (current_thread_info()->addr_limit.seg)); \ | |
54 | flag; \ | |
55 | }) | |
56 | ||
57 | /** | |
58 | * access_ok: - Checks if a user space pointer is valid | |
59 | * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE. Note that | |
60 | * %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe | |
61 | * to write to a block, it is always safe to read from it. | |
62 | * @addr: User space pointer to start of block to check | |
63 | * @size: Size of block to check | |
64 | * | |
65 | * Context: User context only. This function may sleep. | |
66 | * | |
67 | * Checks if a pointer to a block of memory in user space is valid. | |
68 | * | |
69 | * Returns true (nonzero) if the memory block may be valid, false (zero) | |
70 | * if it is definitely invalid. | |
71 | * | |
72 | * Note that, depending on architecture, this function probably just | |
73 | * checks that the pointer is in the user space range - after calling | |
74 | * this function, memory access functions may still return -EFAULT. | |
75 | */ | |
76 | #define access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0)) | |
77 | ||
78 | /* | |
79 | * The exception table consists of pairs of addresses: the first is the | |
80 | * address of an instruction that is allowed to fault, and the second is | |
81 | * the address at which the program should continue. No registers are | |
82 | * modified, so it is entirely up to the continuation code to figure out | |
83 | * what to do. | |
84 | * | |
85 | * All the routines below use bits of fixup code that are out of line | |
86 | * with the main instruction path. This means when everything is well, | |
87 | * we don't even have to jump over them. Further, they do not intrude | |
88 | * on our cache or tlb entries. | |
89 | */ | |
90 | ||
91 | struct exception_table_entry { | |
92 | unsigned long insn, fixup; | |
93 | }; | |
94 | ||
95 | extern int fixup_exception(struct pt_regs *regs); | |
96 | ||
97 | /* | |
98 | * These are the main single-value transfer routines. They automatically | |
99 | * use the right size if we just have the right pointer type. | |
100 | * | |
101 | * This gets kind of ugly. We want to return _two_ values in "get_user()" | |
102 | * and yet we don't want to do any pointers, because that is too much | |
103 | * of a performance impact. Thus we have a few rather ugly macros here, | |
104 | * and hide all the ugliness from the user. | |
105 | * | |
106 | * The "__xxx" versions of the user access functions are versions that | |
107 | * do not verify the address space, that must have been done previously | |
108 | * with a separate "access_ok()" call (this is used when we do multiple | |
109 | * accesses to the same area of user memory). | |
110 | */ | |
111 | ||
112 | extern int __get_user_1(void); | |
113 | extern int __get_user_2(void); | |
114 | extern int __get_user_4(void); | |
115 | extern int __get_user_8(void); | |
116 | extern int __get_user_bad(void); | |
117 | ||
118 | #define __get_user_x(size, ret, x, ptr) \ | |
119 | asm volatile("call __get_user_" #size \ | |
120 | : "=a" (ret),"=d" (x) \ | |
121 | : "0" (ptr)) \ | |
122 | ||
865e5b76 GC |
123 | /* Careful: we have to cast the result to the type of the pointer |
124 | * for sign reasons */ | |
125 | ||
126 | /** | |
127 | * get_user: - Get a simple variable from user space. | |
128 | * @x: Variable to store result. | |
129 | * @ptr: Source address, in user space. | |
130 | * | |
131 | * Context: User context only. This function may sleep. | |
132 | * | |
133 | * This macro copies a single simple variable from user space to kernel | |
134 | * space. It supports simple types like char and int, but not larger | |
135 | * data types like structures or arrays. | |
136 | * | |
137 | * @ptr must have pointer-to-simple-variable type, and the result of | |
138 | * dereferencing @ptr must be assignable to @x without a cast. | |
139 | * | |
140 | * Returns zero on success, or -EFAULT on error. | |
141 | * On error, the variable @x is set to zero. | |
142 | */ | |
143 | #ifdef CONFIG_X86_32 | |
144 | #define __get_user_8(__ret_gu, __val_gu, ptr) \ | |
145 | __get_user_x(X, __ret_gu, __val_gu, ptr) | |
146 | #else | |
147 | #define __get_user_8(__ret_gu, __val_gu, ptr) \ | |
148 | __get_user_x(8, __ret_gu, __val_gu, ptr) | |
149 | #endif | |
150 | ||
151 | #define get_user(x, ptr) \ | |
152 | ({ \ | |
153 | int __ret_gu; \ | |
154 | unsigned long __val_gu; \ | |
155 | __chk_user_ptr(ptr); \ | |
156 | switch (sizeof(*(ptr))) { \ | |
157 | case 1: \ | |
158 | __get_user_x(1, __ret_gu, __val_gu, ptr); \ | |
159 | break; \ | |
160 | case 2: \ | |
161 | __get_user_x(2, __ret_gu, __val_gu, ptr); \ | |
162 | break; \ | |
163 | case 4: \ | |
164 | __get_user_x(4, __ret_gu, __val_gu, ptr); \ | |
165 | break; \ | |
166 | case 8: \ | |
167 | __get_user_8(__ret_gu, __val_gu, ptr); \ | |
168 | break; \ | |
169 | default: \ | |
170 | __get_user_x(X, __ret_gu, __val_gu, ptr); \ | |
171 | break; \ | |
172 | } \ | |
173 | (x) = (__typeof__(*(ptr)))__val_gu; \ | |
174 | __ret_gu; \ | |
175 | }) | |
176 | ||
177 | ||
96a388de TG |
178 | #ifdef CONFIG_X86_32 |
179 | # include "uaccess_32.h" | |
180 | #else | |
181 | # include "uaccess_64.h" | |
182 | #endif | |
ca233862 GC |
183 | |
184 | #endif |