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/compiler.h>
   8 #include <linux/errno.h>
   9 #include <linux/prefetch.h>
  10 #include <asm/page.h>
  11
  12 #define VERIFY_READ 0
  13 #define VERIFY_WRITE 1
  14
  15 /*
  16  * The fs value determines whether argument validity checking should be
  17  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  18  * get_fs() == KERNEL_DS, checking is bypassed.
  19  *
  20  * For historical reasons, these macros are grossly misnamed.
  21  */
  22
  23 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  24
  25 #define KERNEL_DS       MAKE_MM_SEG(0xFFFFFFFFFFFFFFFFUL)
  26 #define USER_DS         MAKE_MM_SEG(PAGE_OFFSET)
  27
  28 #define get_ds()        (KERNEL_DS)
  29 #define get_fs()        (current_thread_info()->addr_limit)
  30 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  31
  32 #define segment_eq(a,b) ((a).seg == (b).seg)
  33
  34 #define __addr_ok(addr) (!((unsigned long)(addr) & (current_thread_info()->addr_limit.seg)))
  35
  36 /*
  37  * Uhhuh, this needs 65-bit arithmetic. We have a carry..
  38  */
  39 #define __range_not_ok(addr,size) ({ \
  40         unsigned long flag,roksum; \
  41         __chk_user_ptr(addr); \
  42         asm("# range_ok\n\r" \
  43                 "addq %3,%1 ; sbbq %0,%0 ; cmpq %1,%4 ; sbbq $0,%0"  \
  44                 :"=&r" (flag), "=r" (roksum) \
  45                 :"1" (addr),"g" ((long)(size)),"g" (current_thread_info()->addr_limit.seg)); \
  46         flag; })
  47
  48 #define access_ok(type, addr, size) (__range_not_ok(addr,size) == 0)
  49
  50 /*
  51  * The exception table consists of pairs of addresses: the first is the
  52  * address of an instruction that is allowed to fault, and the second is
  53  * the address at which the program should continue.  No registers are
  54  * modified, so it is entirely up to the continuation code to figure out
  55  * what to do.
  56  *
  57  * All the routines below use bits of fixup code that are out of line
  58  * with the main instruction path.  This means when everything is well,
  59  * we don't even have to jump over them.  Further, they do not intrude
  60  * on our cache or tlb entries.
  61  */
  62
  63 struct exception_table_entry
  64 {
  65         unsigned long insn, fixup;
  66 };
  67
  68 #define ARCH_HAS_SEARCH_EXTABLE
  69
  70 /*
  71  * These are the main single-value transfer routines.  They automatically
  72  * use the right size if we just have the right pointer type.
  73  *
  74  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  75  * and yet we don't want to do any pointers, because that is too much
  76  * of a performance impact. Thus we have a few rather ugly macros here,
  77  * and hide all the ugliness from the user.
  78  *
  79  * The "__xxx" versions of the user access functions are versions that
  80  * do not verify the address space, that must have been done previously
  81  * with a separate "access_ok()" call (this is used when we do multiple
  82  * accesses to the same area of user memory).
  83  */
  84
  85 #define __get_user_x(size,ret,x,ptr) \
  86         asm volatile("call __get_user_" #size \
  87                 :"=a" (ret),"=d" (x) \
  88                 :"c" (ptr) \
  89                 :"r8")
  90
  91 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
  92 #define get_user(x,ptr)                                                 \
  93 ({      unsigned long __val_gu;                                         \
  94         int __ret_gu;                                                   \
  95         __chk_user_ptr(ptr);                                            \
  96         switch(sizeof (*(ptr))) {                                       \
  97         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
  98         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
  99         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 100         case 8:  __get_user_x(8,__ret_gu,__val_gu,ptr); break;          \
 101         default: __get_user_bad(); break;                               \
 102         }                                                               \
 103         (x) = (typeof(*(ptr)))__val_gu;                         \
 104         __ret_gu;                                                       \
 105 })
 106
 107 extern void __put_user_1(void);
 108 extern void __put_user_2(void);
 109 extern void __put_user_4(void);
 110 extern void __put_user_8(void);
 111 extern void __put_user_bad(void);
 112
 113 #define __put_user_x(size,ret,x,ptr)                                    \
 114         asm volatile("call __put_user_" #size                   \
 115                 :"=a" (ret)                                             \
 116                 :"c" (ptr),"d" (x)                                      \
 117                 :"r8")
 118
 119 #define put_user(x,ptr)                                                 \
 120   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 121
 122 #define __get_user(x,ptr) \
 123   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 124 #define __put_user(x,ptr) \
 125   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 126
 127 #define __get_user_unaligned __get_user
 128 #define __put_user_unaligned __put_user
 129
 130 #define __put_user_nocheck(x,ptr,size)                  \
 131 ({                                                      \
 132         int __pu_err;                                   \
 133         __put_user_size((x),(ptr),(size),__pu_err);     \
 134         __pu_err;                                       \
 135 })
 136
 137
 138 #define __put_user_check(x,ptr,size)                    \
 139 ({                                                      \
 140         int __pu_err;                                   \
 141         typeof(*(ptr)) __user *__pu_addr = (ptr);       \
 142         switch (size) {                                 \
 143         case 1: __put_user_x(1,__pu_err,x,__pu_addr); break;    \
 144         case 2: __put_user_x(2,__pu_err,x,__pu_addr); break;    \
 145         case 4: __put_user_x(4,__pu_err,x,__pu_addr); break;    \
 146         case 8: __put_user_x(8,__pu_err,x,__pu_addr); break;    \
 147         default: __put_user_bad();                      \
 148         }                                               \
 149         __pu_err;                                       \
 150 })
 151
 152 #define __put_user_size(x,ptr,size,retval)                              \
 153 do {                                                                    \
 154         retval = 0;                                                     \
 155         __chk_user_ptr(ptr);                                            \
 156         switch (size) {                                                 \
 157           case 1: __put_user_asm(x,ptr,retval,"b","b","iq",-EFAULT); break;\
 158           case 2: __put_user_asm(x,ptr,retval,"w","w","ir",-EFAULT); break;\
 159           case 4: __put_user_asm(x,ptr,retval,"l","k","ir",-EFAULT); break;\
 160           case 8: __put_user_asm(x,ptr,retval,"q","","Zr",-EFAULT); break;\
 161           default: __put_user_bad();                                    \
 162         }                                                               \
 163 } while (0)
 164
 165 /* FIXME: this hack is definitely wrong -AK */
 166 struct __large_struct { unsigned long buf[100]; };
 167 #define __m(x) (*(struct __large_struct __user *)(x))
 168
 169 /*
 170  * Tell gcc we read from memory instead of writing: this is because
 171  * we do not write to any memory gcc knows about, so there are no
 172  * aliasing issues.
 173  */
 174 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 175         asm volatile(                                   \
 176                 "1:     mov"itype" %"rtype"1,%2\n"              \
 177                 "2:\n"                                          \
 178                 ".section .fixup,\"ax\"\n"                      \
 179                 "3:     mov %3,%0\n"                            \
 180                 "       jmp 2b\n"                               \
 181                 ".previous\n"                                   \
 182                 ".section __ex_table,\"a\"\n"                   \
 183                 "       .align 8\n"                             \
 184                 "       .quad 1b,3b\n"                          \
 185                 ".previous"                                     \
 186                 : "=r"(err)                                     \
 187                 : ltype (x), "m"(__m(addr)), "i"(errno), "0"(err))
 188
 189
 190 #define __get_user_nocheck(x,ptr,size)                          \
 191 ({                                                              \
 192         int __gu_err;                                           \
 193         unsigned long __gu_val;                                 \
 194         __get_user_size(__gu_val,(ptr),(size),__gu_err);        \
 195         (x) = (typeof(*(ptr)))__gu_val;                 \
 196         __gu_err;                                               \
 197 })
 198
 199 extern int __get_user_1(void);
 200 extern int __get_user_2(void);
 201 extern int __get_user_4(void);
 202 extern int __get_user_8(void);
 203 extern int __get_user_bad(void);
 204
 205 #define __get_user_size(x,ptr,size,retval)                              \
 206 do {                                                                    \
 207         retval = 0;                                                     \
 208         __chk_user_ptr(ptr);                                            \
 209         switch (size) {                                                 \
 210           case 1: __get_user_asm(x,ptr,retval,"b","b","=q",-EFAULT); break;\
 211           case 2: __get_user_asm(x,ptr,retval,"w","w","=r",-EFAULT); break;\
 212           case 4: __get_user_asm(x,ptr,retval,"l","k","=r",-EFAULT); break;\
 213           case 8: __get_user_asm(x,ptr,retval,"q","","=r",-EFAULT); break;\
 214           default: (x) = __get_user_bad();                              \
 215         }                                                               \
 216 } while (0)
 217
 218 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 219         asm volatile(                                   \
 220                 "1:     mov"itype" %2,%"rtype"1\n"              \
 221                 "2:\n"                                          \
 222                 ".section .fixup,\"ax\"\n"                      \
 223                 "3:     mov %3,%0\n"                            \
 224                 "       xor"itype" %"rtype"1,%"rtype"1\n"       \
 225                 "       jmp 2b\n"                               \
 226                 ".previous\n"                                   \
 227                 ".section __ex_table,\"a\"\n"                   \
 228                 "       .align 8\n"                             \
 229                 "       .quad 1b,3b\n"                          \
 230                 ".previous"                                     \
 231                 : "=r"(err), ltype (x)                          \
 232                 : "m"(__m(addr)), "i"(errno), "0"(err))
 233
 234 /*
 235  * Copy To/From Userspace
 236  */
 237
 238 /* Handles exceptions in both to and from, but doesn't do access_ok */
 239 __must_check unsigned long
 240 copy_user_generic(void *to, const void *from, unsigned len);
 241
 242 __must_check unsigned long
 243 copy_to_user(void __user *to, const void *from, unsigned len);
 244 __must_check unsigned long
 245 copy_from_user(void *to, const void __user *from, unsigned len);
 246 __must_check unsigned long
 247 copy_in_user(void __user *to, const void __user *from, unsigned len);
 248
 249 static __always_inline __must_check
 250 int __copy_from_user(void *dst, const void __user *src, unsigned size)
 251 {
 252         int ret = 0;
 253         if (!__builtin_constant_p(size))
 254                 return copy_user_generic(dst,(__force void *)src,size);
 255         switch (size) {
 256         case 1:__get_user_asm(*(u8*)dst,(u8 __user *)src,ret,"b","b","=q",1);
 257                 return ret;
 258         case 2:__get_user_asm(*(u16*)dst,(u16 __user *)src,ret,"w","w","=r",2);
 259                 return ret;
 260         case 4:__get_user_asm(*(u32*)dst,(u32 __user *)src,ret,"l","k","=r",4);
 261                 return ret;
 262         case 8:__get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",8);
 263                 return ret;
 264         case 10:
 265                 __get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",16);
 266                 if (unlikely(ret)) return ret;
 267                 __get_user_asm(*(u16*)(8+(char*)dst),(u16 __user *)(8+(char __user *)src),ret,"w","w","=r",2);
 268                 return ret;
 269         case 16:
 270                 __get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",16);
 271                 if (unlikely(ret)) return ret;
 272                 __get_user_asm(*(u64*)(8+(char*)dst),(u64 __user *)(8+(char __user *)src),ret,"q","","=r",8);
 273                 return ret;
 274         default:
 275                 return copy_user_generic(dst,(__force void *)src,size);
 276         }
 277 }
 278
 279 static __always_inline __must_check
 280 int __copy_to_user(void __user *dst, const void *src, unsigned size)
 281 {
 282         int ret = 0;
 283         if (!__builtin_constant_p(size))
 284                 return copy_user_generic((__force void *)dst,src,size);
 285         switch (size) {
 286         case 1:__put_user_asm(*(u8*)src,(u8 __user *)dst,ret,"b","b","iq",1);
 287                 return ret;
 288         case 2:__put_user_asm(*(u16*)src,(u16 __user *)dst,ret,"w","w","ir",2);
 289                 return ret;
 290         case 4:__put_user_asm(*(u32*)src,(u32 __user *)dst,ret,"l","k","ir",4);
 291                 return ret;
 292         case 8:__put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",8);
 293                 return ret;
 294         case 10:
 295                 __put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",10);
 296                 if (unlikely(ret)) return ret;
 297                 asm("":::"memory");
 298                 __put_user_asm(4[(u16*)src],4+(u16 __user *)dst,ret,"w","w","ir",2);
 299                 return ret;
 300         case 16:
 301                 __put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",16);
 302                 if (unlikely(ret)) return ret;
 303                 asm("":::"memory");
 304                 __put_user_asm(1[(u64*)src],1+(u64 __user *)dst,ret,"q","","ir",8);
 305                 return ret;
 306         default:
 307                 return copy_user_generic((__force void *)dst,src,size);
 308         }
 309 }
 310
 311 static __always_inline __must_check
 312 int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
 313 {
 314         int ret = 0;
 315         if (!__builtin_constant_p(size))
 316                 return copy_user_generic((__force void *)dst,(__force void *)src,size);
 317         switch (size) {
 318         case 1: {
 319                 u8 tmp;
 320                 __get_user_asm(tmp,(u8 __user *)src,ret,"b","b","=q",1);
 321                 if (likely(!ret))
 322                         __put_user_asm(tmp,(u8 __user *)dst,ret,"b","b","iq",1);
 323                 return ret;
 324         }
 325         case 2: {
 326                 u16 tmp;
 327                 __get_user_asm(tmp,(u16 __user *)src,ret,"w","w","=r",2);
 328                 if (likely(!ret))
 329                         __put_user_asm(tmp,(u16 __user *)dst,ret,"w","w","ir",2);
 330                 return ret;
 331         }
 332
 333         case 4: {
 334                 u32 tmp;
 335                 __get_user_asm(tmp,(u32 __user *)src,ret,"l","k","=r",4);
 336                 if (likely(!ret))
 337                         __put_user_asm(tmp,(u32 __user *)dst,ret,"l","k","ir",4);
 338                 return ret;
 339         }
 340         case 8: {
 341                 u64 tmp;
 342                 __get_user_asm(tmp,(u64 __user *)src,ret,"q","","=r",8);
 343                 if (likely(!ret))
 344                         __put_user_asm(tmp,(u64 __user *)dst,ret,"q","","ir",8);
 345                 return ret;
 346         }
 347         default:
 348                 return copy_user_generic((__force void *)dst,(__force void *)src,size);
 349         }
 350 }
 351
 352 __must_check long
 353 strncpy_from_user(char *dst, const char __user *src, long count);
 354 __must_check long
 355 __strncpy_from_user(char *dst, const char __user *src, long count);
 356 __must_check long strnlen_user(const char __user *str, long n);
 357 __must_check long __strnlen_user(const char __user *str, long n);
 358 __must_check long strlen_user(const char __user *str);
 359 __must_check unsigned long clear_user(void __user *mem, unsigned long len);
 360 __must_check unsigned long __clear_user(void __user *mem, unsigned long len);
 361
 362 __must_check long __copy_from_user_inatomic(void *dst, const void __user *src, unsigned size);
 363
 364 static __must_check __always_inline int
 365 __copy_to_user_inatomic(void __user *dst, const void *src, unsigned size)
 366 {
 367         return copy_user_generic((__force void *)dst, src, size);
 368 }
 369
 370 #endif /* __X86_64_UACCESS_H */