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
  75 /*
  76  * These are the main single-value transfer routines.  They automatically
  77  * use the right size if we just have the right pointer type.
  78  *
  79  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  80  * and yet we don't want to do any pointers, because that is too much
  81  * of a performance impact. Thus we have a few rather ugly macros here,
  82  * and hide all the ugliness from the user.
  83  *
  84  * The "__xxx" versions of the user access functions are versions that
  85  * do not verify the address space, that must have been done previously
  86  * with a separate "access_ok()" call (this is used when we do multiple
  87  * accesses to the same area of user memory).
  88  */
  89
  90 extern void __get_user_1(void);
  91 extern void __get_user_2(void);
  92 extern void __get_user_4(void);
  93 extern void __get_user_8(void);
  94
  95 #define __get_user_x(size,ret,x,ptr) \
  96         __asm__ __volatile__("call __get_user_" #size \
  97                 :"=a" (ret),"=d" (x) \
  98                 :"0" (ptr) \
  99                 :"rbx")
 100
 101 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
 102 #define get_user(x,ptr)                                                 \
 103 ({      long __val_gu;                                                  \
 104         int __ret_gu;                                                   \
 105         switch(sizeof (*(ptr))) {                                       \
 106         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
 107         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 108         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 109         case 8:  __get_user_x(8,__ret_gu,__val_gu,ptr); break;          \
 110         default: __get_user_bad(); break;                               \
 111         }                                                               \
 112         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 113         __ret_gu;                                                       \
 114 })
 115
 116 extern void __put_user_1(void);
 117 extern void __put_user_2(void);
 118 extern void __put_user_4(void);
 119 extern void __put_user_8(void);
 120
 121 extern void __put_user_bad(void);
 122
 123 #define __put_user_x(size,ret,x,ptr)                                    \
 124         __asm__ __volatile__("call __put_user_" #size                   \
 125                 :"=a" (ret)                                             \
 126                 :"0" (ptr),"d" (x)                                      \
 127                 :"rbx")
 128
 129 #define put_user(x,ptr)                                                 \
 130   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 131
 132 #define __get_user(x,ptr) \
 133   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 134 #define __put_user(x,ptr) \
 135   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 136
 137 #define __put_user_nocheck(x,ptr,size)                  \
 138 ({                                                      \
 139         int __pu_err;                                   \
 140         __put_user_size((x),(ptr),(size),__pu_err);     \
 141         __pu_err;                                       \
 142 })
 143
 144
 145 #define __put_user_check(x,ptr,size)                    \
 146 ({                                                      \
 147         int __pu_err = -EFAULT;                         \
 148         __typeof__(*(ptr)) *__pu_addr = (ptr);          \
 149         if (access_ok(VERIFY_WRITE,__pu_addr,size))     \
 150                 __put_user_size((x),__pu_addr,(size),__pu_err); \
 151         __pu_err;                                       \
 152 })
 153
 154 #define __put_user_size(x,ptr,size,retval)                              \
 155 do {                                                                    \
 156         retval = 0;                                                     \
 157         switch (size) {                                                 \
 158           case 1: __put_user_asm(x,ptr,retval,"b","b","iq",-EFAULT); break;\
 159           case 2: __put_user_asm(x,ptr,retval,"w","w","ir",-EFAULT); break;\
 160           case 4: __put_user_asm(x,ptr,retval,"l","k","ir",-EFAULT); break;\
 161           case 8: __put_user_asm(x,ptr,retval,"q","","ir",-EFAULT); break;\
 162           default: __put_user_bad();                                    \
 163         }                                                               \
 164 } while (0)
 165
 166 /* FIXME: this hack is definitely wrong -AK */
 167 struct __large_struct { unsigned long buf[100]; };
 168 #define __m(x) (*(struct __large_struct *)(x))
 169
 170 /*
 171  * Tell gcc we read from memory instead of writing: this is because
 172  * we do not write to any memory gcc knows about, so there are no
 173  * aliasing issues.
 174  */
 175 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 176         __asm__ __volatile__(                           \
 177                 "1:     mov"itype" %"rtype"1,%2\n"      \
 178                 "2:\n"                                                  \
 179                 ".section .fixup,\"ax\"\n"              \
 180                 "3:     mov %3,%0\n"                            \
 181                 "       jmp 2b\n"                                       \
 182                 ".previous\n"                                   \
 183                 ".section __ex_table,\"a\"\n"   \
 184                 "       .align 8\n"                                     \
 185                 "       .quad 1b,3b\n"                          \
 186                 ".previous"                                             \
 187                 : "=r"(err)                                             \
 188                 : ltype (x), "m"(__m(addr)), "i"(errno), "0"(err))
 189
 190
 191 #define __get_user_nocheck(x,ptr,size)                          \
 192 ({                                                              \
 193         int __gu_err;                                           \
 194         long __gu_val;                                          \
 195         __get_user_size(__gu_val,(ptr),(size),__gu_err);        \
 196         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 197         __gu_err;                                               \
 198 })
 199
 200 extern int __get_user_bad(void);
 201
 202 #define __get_user_size(x,ptr,size,retval)                              \
 203 do {                                                                    \
 204         retval = 0;                                                     \
 205         switch (size) {                                                 \
 206           case 1: __get_user_asm(x,ptr,retval,"b","b","=q",-EFAULT); break;\
 207           case 2: __get_user_asm(x,ptr,retval,"w","w","=r",-EFAULT); break;\
 208           case 4: __get_user_asm(x,ptr,retval,"l","k","=r",-EFAULT); break;\
 209           case 8: __get_user_asm(x,ptr,retval,"q","","=r",-EFAULT); break;\
 210           default: (x) = __get_user_bad();                              \
 211         }                                                               \
 212 } while (0)
 213
 214 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 215         __asm__ __volatile__(                                   \
 216                 "1:     mov"itype" %2,%"rtype"1\n"              \
 217                 "2:\n"                                          \
 218                 ".section .fixup,\"ax\"\n"                      \
 219                 "3:     mov %3,%0\n"                            \
 220                 "       xor"itype" %"rtype"1,%"rtype"1\n"       \
 221                 "       jmp 2b\n"                               \
 222                 ".previous\n"                                   \
 223                 ".section __ex_table,\"a\"\n"                   \
 224                 "       .align 8\n"                             \
 225                 "       .quad 1b,3b\n"                          \
 226                 ".previous"                                     \
 227                 : "=r"(err), ltype (x)                          \
 228                 : "m"(__m(addr)), "i"(errno), "0"(err))
 229
 230 /*
 231  * Copy To/From Userspace
 232  */
 233
 234 /* Handles exceptions in both to and from, but doesn't do access_ok */
 235 extern unsigned long copy_user_generic(void *to, const void *from, unsigned len);
 236
 237 extern unsigned long copy_to_user(void *to, const void *from, unsigned len);
 238 extern unsigned long copy_from_user(void *to, const void *from, unsigned len);
 239 extern unsigned long copy_in_user(void *to, const void *from, unsigned len);
 240
 241 static inline int __copy_from_user(void *dst, const void *src, unsigned size)
 242 {
 243         if (!__builtin_constant_p(size))
 244                 return copy_user_generic(dst,src,size);
 245         int ret = 0;
 246         switch (size) {
 247         case 1:__get_user_asm(*(u8*)dst,(u8 *)src,ret,"b","b","=q",1);
 248                 return ret;
 249         case 2:__get_user_asm(*(u16*)dst,(u16*)src,ret,"w","w","=r",2);
 250                 return ret;
 251         case 4:__get_user_asm(*(u32*)dst,(u32*)src,ret,"l","k","=r",4);
 252                 return ret;
 253         case 8:__get_user_asm(*(u64*)dst,(u64*)src,ret,"q","","=r",8);
 254                 return ret;
 255         case 10:
 256                 __get_user_asm(*(u64*)dst,(u64*)src,ret,"q","","=r",16);
 257                 if (ret) return ret;
 258                 __get_user_asm(*(u16*)(8+(char*)dst),(u16*)(8+(char*)src),ret,"w","w","=r",2);
 259                 return ret;
 260         case 16:
 261                 __get_user_asm(*(u64*)dst,(u64*)src,ret,"q","","=r",16);
 262                 if (ret) return ret;
 263                 __get_user_asm(*(u64*)(8+(char*)dst),(u64*)(8+(char*)src),ret,"q","","=r",8);
 264                 return ret;
 265         default:
 266                 return copy_user_generic(dst,src,size);
 267         }
 268 }
 269
 270 static inline int __copy_to_user(void *dst, const void *src, unsigned size)
 271 {
 272         if (!__builtin_constant_p(size))
 273                 return copy_user_generic(dst,src,size);
 274         int ret = 0;
 275         switch (size) {
 276         case 1:__put_user_asm(*(u8*)src,(u8 *)dst,ret,"b","b","iq",1);
 277                 return ret;
 278         case 2:__put_user_asm(*(u16*)src,(u16*)dst,ret,"w","w","ir",2);
 279                 return ret;
 280         case 4:__put_user_asm(*(u32*)src,(u32*)dst,ret,"l","k","ir",4);
 281                 return ret;
 282         case 8:__put_user_asm(*(u64*)src,(u64*)dst,ret,"q","","ir",8);
 283                 return ret;
 284         case 10:
 285                 __put_user_asm(*(u64*)src,(u64*)dst,ret,"q","","ir",10);
 286                 if (ret) return ret;
 287                 asm("":::"memory");
 288                 __put_user_asm(4[(u16*)src],4+(u16*)dst,ret,"w","w","ir",2);
 289                 return ret;
 290         case 16:
 291                 __put_user_asm(*(u64*)src,(u64*)dst,ret,"q","","ir",16);
 292                 if (ret) return ret;
 293                 asm("":::"memory");
 294                 __put_user_asm(1[(u64*)src],1+(u64*)dst,ret,"q","","ir",8);
 295                 return ret;
 296         default:
 297                 return copy_user_generic(dst,src,size);
 298         }
 299 }
 300
 301 static inline int __copy_in_user(void *dst, const void *src, unsigned size)
 302 {
 303        int ret = 0;
 304        if (!__builtin_constant_p(size))
 305                 return copy_user_generic(dst,src,size);
 306        switch (size) {
 307        case 1: {
 308                u8 tmp;
 309                __get_user_asm(tmp,(u8 *)src,ret,"b","b","=q",1);
 310                if (likely(!ret))
 311                        __put_user_asm(tmp,(u8 *)dst,ret,"b","b","iq",1);
 312                return ret;
 313        }
 314        case 2: {
 315                u16 tmp;
 316                __get_user_asm(tmp,(u16 *)src,ret,"w","w","=r",2);
 317                if (likely(!ret))
 318                        __put_user_asm(tmp,(u16 *)dst,ret,"w","w","ir",2);
 319                return ret;
 320        }
 321
 322        case 4: {
 323                u32 tmp;
 324                __get_user_asm(tmp,(u32 *)src,ret,"l","k","=r",4);
 325                if (likely(!ret))
 326                        __put_user_asm(tmp,(u32 *)dst,ret,"l","k","ir",4);
 327                return ret;
 328        }
 329        case 8: {
 330                u64 tmp;
 331                __get_user_asm(tmp,(u64 *)src,ret,"q","","=r",8);
 332                if (likely(!ret))
 333                        __put_user_asm(tmp,(u64 *)dst,ret,"q","","ir",8);
 334                return ret;
 335        }
 336        default:
 337                return copy_user_generic(dst,src,size);
 338        }
 339 }
 340
 341 long strncpy_from_user(char *dst, const char *src, long count);
 342 long __strncpy_from_user(char *dst, const char *src, long count);
 343 long strnlen_user(const char *str, long n);
 344 long strlen_user(const char *str);
 345 unsigned long clear_user(void *mem, unsigned long len);
 346 unsigned long __clear_user(void *mem, unsigned long len);
 347
 348 extern unsigned long search_exception_table(unsigned long);
 349
 350 #endif /* __X86_64_UACCESS_H */