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/compiler.h>
   9 #include <linux/errno.h>
  10 #include <linux/sched.h>
  11 #include <linux/prefetch.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(0xFFFFFFFFFFFFFFFF)
  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 #define __addr_ok(addr) (!((unsigned long)(addr) & (current_thread_info()->addr_limit.seg)))
  37
  38 /*
  39  * Uhhuh, this needs 65-bit arithmetic. We have a carry..
  40  */
  41 #define __range_not_ok(addr,size) ({ \
  42         unsigned long flag,sum; \
  43         asm("# range_ok\n\r" \
  44                 "addq %3,%1 ; sbbq %0,%0 ; cmpq %1,%4 ; sbbq $0,%0"  \
  45                 :"=&r" (flag), "=r" (sum) \
  46                 :"1" (addr),"g" ((long)(size)),"g" (current_thread_info()->addr_limit.seg)); \
  47         flag; })
  48
  49 #define access_ok(type,addr,size) (__range_not_ok(addr,size) == 0)
  50
  51 extern inline int verify_area(int type, const void * addr, unsigned long size)
  52 {
  53         return access_ok(type,addr,size) ? 0 : -EFAULT;
  54 }
  55
  56
  57 /*
  58  * The exception table consists of pairs of addresses: the first is the
  59  * address of an instruction that is allowed to fault, and the second is
  60  * the address at which the program should continue.  No registers are
  61  * modified, so it is entirely up to the continuation code to figure out
  62  * what to do.
  63  *
  64  * All the routines below use bits of fixup code that are out of line
  65  * with the main instruction path.  This means when everything is well,
  66  * we don't even have to jump over them.  Further, they do not intrude
  67  * on our cache or tlb entries.
  68  */
  69
  70 struct exception_table_entry
  71 {
  72         unsigned long insn, fixup;
  73 };
  74
  75
  76 /*
  77  * These are the main single-value transfer routines.  They automatically
  78  * use the right size if we just have the right pointer type.
  79  *
  80  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  81  * and yet we don't want to do any pointers, because that is too much
  82  * of a performance impact. Thus we have a few rather ugly macros here,
  83  * and hide all the ugliness from the user.
  84  *
  85  * The "__xxx" versions of the user access functions are versions that
  86  * do not verify the address space, that must have been done previously
  87  * with a separate "access_ok()" call (this is used when we do multiple
  88  * accesses to the same area of user memory).
  89  */
  90
  91 extern void __get_user_1(void);
  92 extern void __get_user_2(void);
  93 extern void __get_user_4(void);
  94 extern void __get_user_8(void);
  95
  96 #define __get_user_x(size,ret,x,ptr) \
  97         __asm__ __volatile__("call __get_user_" #size \
  98                 :"=a" (ret),"=d" (x) \
  99                 :"0" (ptr) \
 100                 :"rbx")
 101
 102 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
 103 #define get_user(x,ptr)                                                 \
 104 ({      long __val_gu;                                                  \
 105         int __ret_gu;                                                   \
 106         switch(sizeof (*(ptr))) {                                       \
 107         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
 108         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 109         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 110         case 8:  __get_user_x(8,__ret_gu,__val_gu,ptr); break;          \
 111         default: __get_user_bad(); break;                               \
 112         }                                                               \
 113         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 114         __ret_gu;                                                       \
 115 })
 116
 117 extern void __put_user_1(void);
 118 extern void __put_user_2(void);
 119 extern void __put_user_4(void);
 120 extern void __put_user_8(void);
 121
 122 extern void __put_user_bad(void);
 123
 124 #define __put_user_x(size,ret,x,ptr)                                    \
 125         __asm__ __volatile__("call __put_user_" #size                   \
 126                 :"=a" (ret)                                             \
 127                 :"0" (ptr),"d" (x)                                      \
 128                 :"rbx")
 129
 130 #define put_user(x,ptr)                                                 \
 131   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 132
 133 #define __get_user(x,ptr) \
 134   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 135 #define __put_user(x,ptr) \
 136   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 137
 138 #define __put_user_nocheck(x,ptr,size)                  \
 139 ({                                                      \
 140         int __pu_err;                                   \
 141         __put_user_size((x),(ptr),(size),__pu_err);     \
 142         __pu_err;                                       \
 143 })
 144
 145
 146 #define __put_user_check(x,ptr,size)                    \
 147 ({                                                      \
 148         int __pu_err = -EFAULT;                         \
 149         __typeof__(*(ptr)) *__pu_addr = (ptr);          \
 150         if (likely(access_ok(VERIFY_WRITE,__pu_addr,size)))     \
 151                 __put_user_size((x),__pu_addr,(size),__pu_err); \
 152         __pu_err;                                       \
 153 })
 154
 155 #define __put_user_size(x,ptr,size,retval)                              \
 156 do {                                                                    \
 157         retval = 0;                                                     \
 158         switch (size) {                                                 \
 159           case 1: __put_user_asm(x,ptr,retval,"b","b","iq",-EFAULT); break;\
 160           case 2: __put_user_asm(x,ptr,retval,"w","w","ir",-EFAULT); break;\
 161           case 4: __put_user_asm(x,ptr,retval,"l","k","ir",-EFAULT); break;\
 162           case 8: __put_user_asm(x,ptr,retval,"q","","ir",-EFAULT); break;\
 163           default: __put_user_bad();                                    \
 164         }                                                               \
 165 } while (0)
 166
 167 /* FIXME: this hack is definitely wrong -AK */
 168 struct __large_struct { unsigned long buf[100]; };
 169 #define __m(x) (*(struct __large_struct *)(x))
 170
 171 /*
 172  * Tell gcc we read from memory instead of writing: this is because
 173  * we do not write to any memory gcc knows about, so there are no
 174  * aliasing issues.
 175  */
 176 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 177         __asm__ __volatile__(                                   \
 178                 "1:     mov"itype" %"rtype"1,%2\n"              \
 179                 "2:\n"                                          \
 180                 ".section .fixup,\"ax\"\n"                      \
 181                 "3:     mov %3,%0\n"                            \
 182                 "       jmp 2b\n"                               \
 183                 ".previous\n"                                   \
 184                 ".section __ex_table,\"a\"\n"                   \
 185                 "       .align 8\n"                             \
 186                 "       .quad 1b,3b\n"                          \
 187                 ".previous"                                     \
 188                 : "=r"(err)                                     \
 189                 : ltype (x), "m"(__m(addr)), "i"(errno), "0"(err))
 190
 191
 192 #define __get_user_nocheck(x,ptr,size)                          \
 193 ({                                                              \
 194         int __gu_err;                                           \
 195         long __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 int __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",-EFAULT); break;\
 208           case 2: __get_user_asm(x,ptr,retval,"w","w","=r",-EFAULT); break;\
 209           case 4: __get_user_asm(x,ptr,retval,"l","k","=r",-EFAULT); break;\
 210           case 8: __get_user_asm(x,ptr,retval,"q","","=r",-EFAULT); break;\
 211           default: (x) = __get_user_bad();                              \
 212         }                                                               \
 213 } while (0)
 214
 215 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 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"(errno), "0"(err))
 230
 231 /*
 232  * Copy To/From Userspace
 233  */
 234
 235 /* Handles exceptions in both to and from, but doesn't do access_ok */
 236 extern unsigned long copy_user_generic(void *to, const void *from, unsigned len);
 237
 238 extern unsigned long copy_to_user(void *to, const void *from, unsigned len);
 239 extern unsigned long copy_from_user(void *to, const void *from, unsigned len);
 240 extern unsigned long copy_in_user(void *to, const void *from, unsigned len);
 241
 242 static inline int __copy_from_user(void *dst, const void *src, unsigned size)
 243 {
 244        int ret = 0;
 245         if (!__builtin_constant_p(size))
 246                 return copy_user_generic(dst,src,size);
 247         switch (size) {
 248         case 1:__get_user_asm(*(u8*)dst,(u8 *)src,ret,"b","b","=q",1);
 249                 return ret;
 250         case 2:__get_user_asm(*(u16*)dst,(u16*)src,ret,"w","w","=r",2);
 251                 return ret;
 252         case 4:__get_user_asm(*(u32*)dst,(u32*)src,ret,"l","k","=r",4);
 253                 return ret;
 254         case 8:__get_user_asm(*(u64*)dst,(u64*)src,ret,"q","","=r",8);
 255                 return ret;
 256         case 10:
 257                 __get_user_asm(*(u64*)dst,(u64*)src,ret,"q","","=r",16);
 258                 if (unlikely(ret)) return ret;
 259                 __get_user_asm(*(u16*)(8+(char*)dst),(u16*)(8+(char*)src),ret,"w","w","=r",2);
 260                 return ret;
 261         case 16:
 262                 __get_user_asm(*(u64*)dst,(u64*)src,ret,"q","","=r",16);
 263                 if (unlikely(ret)) return ret;
 264                 __get_user_asm(*(u64*)(8+(char*)dst),(u64*)(8+(char*)src),ret,"q","","=r",8);
 265                 return ret;
 266         default:
 267                 return copy_user_generic(dst,src,size);
 268         }
 269 }
 270
 271 static inline int __copy_to_user(void *dst, const void *src, unsigned size)
 272 {
 273        int ret = 0;
 274         if (!__builtin_constant_p(size))
 275                 return copy_user_generic(dst,src,size);
 276         switch (size) {
 277         case 1:__put_user_asm(*(u8*)src,(u8 *)dst,ret,"b","b","iq",1);
 278                 return ret;
 279         case 2:__put_user_asm(*(u16*)src,(u16*)dst,ret,"w","w","ir",2);
 280                 return ret;
 281         case 4:__put_user_asm(*(u32*)src,(u32*)dst,ret,"l","k","ir",4);
 282                 return ret;
 283         case 8:__put_user_asm(*(u64*)src,(u64*)dst,ret,"q","","ir",8);
 284                 return ret;
 285         case 10:
 286                 __put_user_asm(*(u64*)src,(u64*)dst,ret,"q","","ir",10);
 287                 if (unlikely(ret)) return ret;
 288                 asm("":::"memory");
 289                 __put_user_asm(4[(u16*)src],4+(u16*)dst,ret,"w","w","ir",2);
 290                 return ret;
 291         case 16:
 292                 __put_user_asm(*(u64*)src,(u64*)dst,ret,"q","","ir",16);
 293                 if (unlikely(ret)) return ret;
 294                 asm("":::"memory");
 295                 __put_user_asm(1[(u64*)src],1+(u64*)dst,ret,"q","","ir",8);
 296                 return ret;
 297         default:
 298                 return copy_user_generic(dst,src,size);
 299         }
 300 }
 301
 302
 303 static inline int __copy_in_user(void *dst, const void *src, unsigned size)
 304 {
 305        int ret = 0;
 306         if (!__builtin_constant_p(size))
 307                 return copy_user_generic(dst,src,size);
 308         switch (size) {
 309         case 1: {
 310                 u8 tmp;
 311                 __get_user_asm(tmp,(u8 *)src,ret,"b","b","=q",1);
 312                 if (likely(!ret))
 313                         __put_user_asm(tmp,(u8 *)dst,ret,"b","b","iq",1);
 314                 return ret;
 315         }
 316         case 2: {
 317                 u16 tmp;
 318                 __get_user_asm(tmp,(u16 *)src,ret,"w","w","=r",2);
 319                 if (likely(!ret))
 320                         __put_user_asm(tmp,(u16 *)dst,ret,"w","w","ir",2);
 321                 return ret;
 322         }
 323
 324         case 4: {
 325                 u32 tmp;
 326                 __get_user_asm(tmp,(u32 *)src,ret,"l","k","=r",4);
 327                 if (likely(!ret))
 328                         __put_user_asm(tmp,(u32 *)dst,ret,"l","k","ir",4);
 329                 return ret;
 330         }
 331         case 8: {
 332                 u64 tmp;
 333                 __get_user_asm(tmp,(u64 *)src,ret,"q","","=r",8);
 334                 if (likely(!ret))
 335                         __put_user_asm(tmp,(u64 *)dst,ret,"q","","ir",8);
 336                 return ret;
 337         }
 338         default:
 339                 return copy_user_generic(dst,src,size);
 340         }
 341 }
 342
 343 long strncpy_from_user(char *dst, const char *src, long count);
 344 long __strncpy_from_user(char *dst, const char *src, long count);
 345 long strnlen_user(const char *str, long n);
 346 long strlen_user(const char *str);
 347 unsigned long clear_user(void *mem, unsigned long len);
 348 unsigned long __clear_user(void *mem, unsigned long len);
 349
 350 #endif /* __X86_64_UACCESS_H */