include/asm-x86_64/uaccess.h

   1 #ifndef __X86_64_UACCESS_H
   2 #define __X86_64_UACCESS_H
   3
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/config.h>
   8 #include <linux/errno.h>
   9 #include <linux/sched.h>
  10 #include <linux/prefetch.h>
  11 #include <asm/page.h>
  12
  13 #define VERIFY_READ 0
  14 #define VERIFY_WRITE 1
  15
  16 /*
  17  * The fs value determines whether argument validity checking should be
  18  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  19  * get_fs() == KERNEL_DS, checking is bypassed.
  20  *
  21  * For historical reasons, these macros are grossly misnamed.
  22  */
  23
  24 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  25
  26 #define KERNEL_DS       MAKE_MM_SEG(0xFFFFFFFFFFFFFFFF)
  27 #define USER_DS         MAKE_MM_SEG(PAGE_OFFSET)
  28
  29 #define get_ds()        (KERNEL_DS)
  30 #define get_fs()        (current->addr_limit)
  31 #define set_fs(x)       (current->addr_limit = (x))
  32
  33 #define segment_eq(a,b) ((a).seg == (b).seg)
  34
  35 #define __addr_ok(addr) (!((unsigned long)(addr) & (current->addr_limit.seg)))
  36
  37 /*
  38  * Uhhuh, this needs 65-bit arithmetic. We have a carry..
  39  */
  40 #define __range_not_ok(addr,size) ({ \
  41         unsigned long flag,sum; \
  42         asm("# range_ok\n\r" \
  43                 "addq %3,%1 ; sbbq %0,%0 ; cmpq %1,%4 ; sbbq $0,%0"  \
  44                 :"=&r" (flag), "=r" (sum) \
  45                 :"1" (addr),"g" ((long)(size)),"g" (current->addr_limit.seg)); \
  46         flag; })
  47
  48 #define access_ok(type,addr,size) (__range_not_ok(addr,size) == 0)
  49
  50 extern inline int verify_area(int type, const void * addr, unsigned long size)
  51 {
  52         return access_ok(type,addr,size) ? 0 : -EFAULT;
  53 }
  54
  55
  56 /*
  57  * The exception table consists of pairs of addresses: the first is the
  58  * address of an instruction that is allowed to fault, and the second is
  59  * the address at which the program should continue.  No registers are
  60  * modified, so it is entirely up to the continuation code to figure out
  61  * what to do.
  62  *
  63  * All the routines below use bits of fixup code that are out of line
  64  * with the main instruction path.  This means when everything is well,
  65  * we don't even have to jump over them.  Further, they do not intrude
  66  * on our cache or tlb entries.
  67  */
  68
  69 struct exception_table_entry
  70 {
  71         unsigned long insn, fixup;
  72 };
  73
  74 /* Returns 0 if exception not found and fixup otherwise.  */
  75 extern unsigned long search_exception_table(unsigned long);
  76
  77
  78 /*
  79  * These are the main single-value transfer routines.  They automatically
  80  * use the right size if we just have the right pointer type.
  81  *
  82  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  83  * and yet we don't want to do any pointers, because that is too much
  84  * of a performance impact. Thus we have a few rather ugly macros here,
  85  * and hide all the uglyness from the user.
  86  *
  87  * The "__xxx" versions of the user access functions are versions that
  88  * do not verify the address space, that must have been done previously
  89  * with a separate "access_ok()" call (this is used when we do multiple
  90  * accesses to the same area of user memory).
  91  */
  92
  93 extern void __get_user_1(void);
  94 extern void __get_user_2(void);
  95 extern void __get_user_4(void);
  96 extern void __get_user_8(void);
  97
  98 #define __get_user_x(size,ret,x,ptr) \
  99         __asm__ __volatile__("call __get_user_" #size \
 100                 :"=a" (ret),"=d" (x) \
 101                 :"0" (ptr) \
 102                 :"rbx")
 103
 104 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
 105 #define get_user(x,ptr)                                                 \
 106 ({      long __ret_gu,__val_gu;                                         \
 107         switch(sizeof (*(ptr))) {                                       \
 108         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
 109         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 110         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 111         case 8:  __get_user_x(8,__ret_gu,__val_gu,ptr); break;          \
 112         default: __get_user_bad(); break;                               \
 113         }                                                               \
 114         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 115         __ret_gu;                                                       \
 116 })
 117
 118 extern void __put_user_1(void);
 119 extern void __put_user_2(void);
 120 extern void __put_user_4(void);
 121 extern void __put_user_8(void);
 122
 123 extern void __put_user_bad(void);
 124
 125 #define __put_user_x(size,ret,x,ptr)                                    \
 126         __asm__ __volatile__("call __put_user_" #size                   \
 127                 :"=a" (ret)                                             \
 128                 :"0" (ptr),"d" (x)                                      \
 129                 :"rbx")
 130
 131 #define put_user(x,ptr)                                                 \
 132   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 133
 134 #define __get_user(x,ptr) \
 135   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 136 #define __put_user(x,ptr) \
 137   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 138
 139 #define __put_user_nocheck(x,ptr,size)                  \
 140 ({                                                      \
 141         long __pu_err;                                  \
 142         __put_user_size((x),(ptr),(size),__pu_err);     \
 143         __pu_err;                                       \
 144 })
 145
 146
 147 #define __put_user_check(x,ptr,size)                    \
 148 ({                                                      \
 149         long __pu_err = -EFAULT;                        \
 150         __typeof__(*(ptr)) *__pu_addr = (ptr);          \
 151         if (access_ok(VERIFY_WRITE,__pu_addr,size))     \
 152                 __put_user_size((x),__pu_addr,(size),__pu_err); \
 153         __pu_err;                                       \
 154 })
 155
 156 #define __put_user_size(x,ptr,size,retval)                              \
 157 do {                                                                    \
 158         retval = 0;                                                     \
 159         switch (size) {                                                 \
 160           case 1: __put_user_asm(x,ptr,retval,"b","b","iq"); break;     \
 161           case 2: __put_user_asm(x,ptr,retval,"w","w","ir"); break;     \
 162           case 4: __put_user_asm(x,ptr,retval,"l","k","ir"); break;     \
 163           case 8: __put_user_asm(x,ptr,retval,"q","","ir"); break;      \
 164           default: __put_user_bad();                                    \
 165         }                                                               \
 166 } while (0)
 167
 168 /* FIXME: this hack is definitely wrong -AK */
 169 struct __large_struct { unsigned long buf[100]; };
 170 #define __m(x) (*(struct __large_struct *)(x))
 171
 172 /*
 173  * Tell gcc we read from memory instead of writing: this is because
 174  * we do not write to any memory gcc knows about, so there are no
 175  * aliasing issues.
 176  */
 177 #define __put_user_asm(x, addr, err, itype, rtype, ltype)       \
 178         __asm__ __volatile__(                           \
 179                 "1:     mov"itype" %"rtype"1,%2\n"      \
 180                 "2:\n"                                                  \
 181                 ".section .fixup,\"ax\"\n"              \
 182                 "3:     movq %3,%0\n"                           \
 183                 "       jmp 2b\n"                                       \
 184                 ".previous\n"                                   \
 185                 ".section __ex_table,\"a\"\n"   \
 186                 "       .align 8\n"                                     \
 187                 "       .quad 1b,3b\n"                          \
 188                 ".previous"                                             \
 189                 : "=r"(err)                                             \
 190                 : ltype (x), "m"(__m(addr)), "i"(-EFAULT), "0"(err))
 191
 192
 193 #define __get_user_nocheck(x,ptr,size)                          \
 194 ({                                                              \
 195         long __gu_err, __gu_val;                                \
 196         __get_user_size(__gu_val,(ptr),(size),__gu_err);        \
 197         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 198         __gu_err;                                               \
 199 })
 200
 201 extern long __get_user_bad(void);
 202
 203 #define __get_user_size(x,ptr,size,retval)                              \
 204 do {                                                                    \
 205         retval = 0;                                                     \
 206         switch (size) {                                                 \
 207           case 1: __get_user_asm(x,ptr,retval,"b","b","=q"); break;     \
 208           case 2: __get_user_asm(x,ptr,retval,"w","w","=r"); break;     \
 209           case 4: __get_user_asm(x,ptr,retval,"l","k","=r"); break;     \
 210           case 8: __get_user_asm(x,ptr,retval,"q","","=r"); break;      \
 211           default: (x) = __get_user_bad();                              \
 212         }                                                               \
 213 } while (0)
 214
 215 #define __get_user_asm(x, addr, err, itype, rtype, ltype)       \
 216         __asm__ __volatile__(                                   \
 217                 "1:     mov"itype" %2,%"rtype"1\n"              \
 218                 "2:\n"                                          \
 219                 ".section .fixup,\"ax\"\n"                      \
 220                 "3:     mov %3,%0\n"                            \
 221                 "       xor"itype" %"rtype"1,%"rtype"1\n"       \
 222                 "       jmp 2b\n"                               \
 223                 ".previous\n"                                   \
 224                 ".section __ex_table,\"a\"\n"                   \
 225                 "       .align 8\n"                             \
 226                 "       .quad 1b,3b\n"                          \
 227                 ".previous"                                     \
 228                 : "=r"(err), ltype (x)                          \
 229                 : "m"(__m(addr)), "i"(-EFAULT), "0"(err))
 230
 231 /*
 232  * Copy To/From Userspace
 233  *
 234  * This relies on an optimized common worker function.
 235  *
 236  * Could do special inline versions for small constant copies, but avoid this
 237  * for now. It's not clear it is worth it.
 238  */
 239
 240 extern unsigned long copy_user_generic(void *to, const void *from, unsigned len);
 241
 242 extern unsigned long copy_to_user(void *to, const void *from, unsigned len);
 243 extern unsigned long copy_from_user(void *to, const void *from, unsigned len);
 244 #define __copy_to_user copy_user_generic
 245 #define __copy_from_user copy_user_generic
 246
 247 long strncpy_from_user(char *dst, const char *src, long count);
 248 long __strncpy_from_user(char *dst, const char *src, long count);
 249 #define strlen_user(str) strnlen_user(str, ~0UL >> 1)
 250 long strnlen_user(const char *str, long n);
 251 unsigned long clear_user(void *mem, unsigned long len);
 252 unsigned long __clear_user(void *mem, unsigned long len);
 253
 254 #endif /* __X86_64_UACCESS_H */