1 #ifndef _ASM_X86_UACCESS_32_H 2 #define _ASM_X86_UACCESS_32_H 3 4 /* 5 * User space memory access functions 6 */ 7 #include <linux/errno.h> 8 #include <linux/thread_info.h> 9 #include <linux/string.h> 10 #include <asm/asm.h> 11 #include <asm/page.h> 12 13 unsigned long __must_check __copy_to_user_ll 14 (void __user *to, const void *from, unsigned long n); 15 unsigned long __must_check __copy_from_user_ll 16 (void *to, const void __user *from, unsigned long n); 17 unsigned long __must_check __copy_from_user_ll_nozero 18 (void *to, const void __user *from, unsigned long n); 19 unsigned long __must_check __copy_from_user_ll_nocache 20 (void *to, const void __user *from, unsigned long n); 21 unsigned long __must_check __copy_from_user_ll_nocache_nozero 22 (void *to, const void __user *from, unsigned long n); 23 24 /** 25 * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking. 26 * @to: Destination address, in user space. 27 * @from: Source address, in kernel space. 28 * @n: Number of bytes to copy. 29 * 30 * Context: User context only. 31 * 32 * Copy data from kernel space to user space. Caller must check 33 * the specified block with access_ok() before calling this function. 34 * The caller should also make sure he pins the user space address 35 * so that we don't result in page fault and sleep. 36 * 37 * Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault 38 * we return the initial request size (1, 2 or 4), as copy_*_user should do. 39 * If a store crosses a page boundary and gets a fault, the x86 will not write 40 * anything, so this is accurate. 41 */ 42 43 static __always_inline unsigned long __must_check 44 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) 45 { 46 if (__builtin_constant_p(n)) { 47 unsigned long ret; 48 49 switch (n) { 50 case 1: 51 __put_user_size(*(u8 *)from, (u8 __user *)to, 52 1, ret, 1); 53 return ret; 54 case 2: 55 __put_user_size(*(u16 *)from, (u16 __user *)to, 56 2, ret, 2); 57 return ret; 58 case 4: 59 __put_user_size(*(u32 *)from, (u32 __user *)to, 60 4, ret, 4); 61 return ret; 62 case 8: 63 __put_user_size(*(u64 *)from, (u64 __user *)to, 64 8, ret, 8); 65 return ret; 66 } 67 } 68 return __copy_to_user_ll(to, from, n); 69 } 70 71 /** 72 * __copy_to_user: - Copy a block of data into user space, with less checking. 73 * @to: Destination address, in user space. 74 * @from: Source address, in kernel space. 75 * @n: Number of bytes to copy. 76 * 77 * Context: User context only. This function may sleep if pagefaults are 78 * enabled. 79 * 80 * Copy data from kernel space to user space. Caller must check 81 * the specified block with access_ok() before calling this function. 82 * 83 * Returns number of bytes that could not be copied. 84 * On success, this will be zero. 85 */ 86 static __always_inline unsigned long __must_check 87 __copy_to_user(void __user *to, const void *from, unsigned long n) 88 { 89 might_fault(); 90 return __copy_to_user_inatomic(to, from, n); 91 } 92 93 static __always_inline unsigned long 94 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n) 95 { 96 /* Avoid zeroing the tail if the copy fails.. 97 * If 'n' is constant and 1, 2, or 4, we do still zero on a failure, 98 * but as the zeroing behaviour is only significant when n is not 99 * constant, that shouldn't be a problem. 100 */ 101 if (__builtin_constant_p(n)) { 102 unsigned long ret; 103 104 switch (n) { 105 case 1: 106 __get_user_size(*(u8 *)to, from, 1, ret, 1); 107 return ret; 108 case 2: 109 __get_user_size(*(u16 *)to, from, 2, ret, 2); 110 return ret; 111 case 4: 112 __get_user_size(*(u32 *)to, from, 4, ret, 4); 113 return ret; 114 } 115 } 116 return __copy_from_user_ll_nozero(to, from, n); 117 } 118 119 /** 120 * __copy_from_user: - Copy a block of data from user space, with less checking. 121 * @to: Destination address, in kernel space. 122 * @from: Source address, in user space. 123 * @n: Number of bytes to copy. 124 * 125 * Context: User context only. This function may sleep if pagefaults are 126 * enabled. 127 * 128 * Copy data from user space to kernel space. Caller must check 129 * the specified block with access_ok() before calling this function. 130 * 131 * Returns number of bytes that could not be copied. 132 * On success, this will be zero. 133 * 134 * If some data could not be copied, this function will pad the copied 135 * data to the requested size using zero bytes. 136 * 137 * An alternate version - __copy_from_user_inatomic() - may be called from 138 * atomic context and will fail rather than sleep. In this case the 139 * uncopied bytes will *NOT* be padded with zeros. See fs/filemap.h 140 * for explanation of why this is needed. 141 */ 142 static __always_inline unsigned long 143 __copy_from_user(void *to, const void __user *from, unsigned long n) 144 { 145 might_fault(); 146 if (__builtin_constant_p(n)) { 147 unsigned long ret; 148 149 switch (n) { 150 case 1: 151 __get_user_size(*(u8 *)to, from, 1, ret, 1); 152 return ret; 153 case 2: 154 __get_user_size(*(u16 *)to, from, 2, ret, 2); 155 return ret; 156 case 4: 157 __get_user_size(*(u32 *)to, from, 4, ret, 4); 158 return ret; 159 } 160 } 161 return __copy_from_user_ll(to, from, n); 162 } 163 164 static __always_inline unsigned long __copy_from_user_nocache(void *to, 165 const void __user *from, unsigned long n) 166 { 167 might_fault(); 168 if (__builtin_constant_p(n)) { 169 unsigned long ret; 170 171 switch (n) { 172 case 1: 173 __get_user_size(*(u8 *)to, from, 1, ret, 1); 174 return ret; 175 case 2: 176 __get_user_size(*(u16 *)to, from, 2, ret, 2); 177 return ret; 178 case 4: 179 __get_user_size(*(u32 *)to, from, 4, ret, 4); 180 return ret; 181 } 182 } 183 return __copy_from_user_ll_nocache(to, from, n); 184 } 185 186 static __always_inline unsigned long 187 __copy_from_user_inatomic_nocache(void *to, const void __user *from, 188 unsigned long n) 189 { 190 return __copy_from_user_ll_nocache_nozero(to, from, n); 191 } 192 193 #endif /* _ASM_X86_UACCESS_32_H */ 194