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/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(0xFFFFFFFFFFFFFFFFUL)
  27 #define USER_DS         MAKE_MM_SEG(PAGE_OFFSET)
  28
  29 #define get_ds()        (KERNEL_DS)
  30 #define get_fs()        (current_thread_info()->addr_limit)
  31 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  32
  33 #define segment_eq(a,b) ((a).seg == (b).seg)
  34
  35 #define __addr_ok(addr) (!((unsigned long)(addr) & (current_thread_info()->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         __chk_user_ptr(addr); \
  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 /*
  52  * The exception table consists of pairs of addresses: the first is the
  53  * address of an instruction that is allowed to fault, and the second is
  54  * the address at which the program should continue.  No registers are
  55  * modified, so it is entirely up to the continuation code to figure out
  56  * what to do.
  57  *
  58  * All the routines below use bits of fixup code that are out of line
  59  * with the main instruction path.  This means when everything is well,
  60  * we don't even have to jump over them.  Further, they do not intrude
  61  * on our cache or tlb entries.
  62  */
  63
  64 struct exception_table_entry
  65 {
  66         unsigned long insn, fixup;
  67 };
  68
  69 #define ARCH_HAS_SEARCH_EXTABLE
  70
  71 /*
  72  * These are the main single-value transfer routines.  They automatically
  73  * use the right size if we just have the right pointer type.
  74  *
  75  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  76  * and yet we don't want to do any pointers, because that is too much
  77  * of a performance impact. Thus we have a few rather ugly macros here,
  78  * and hide all the ugliness from the user.
  79  *
  80  * The "__xxx" versions of the user access functions are versions that
  81  * do not verify the address space, that must have been done previously
  82  * with a separate "access_ok()" call (this is used when we do multiple
  83  * accesses to the same area of user memory).
  84  */
  85
  86 #define __get_user_x(size,ret,x,ptr) \
  87         asm volatile("call __get_user_" #size \
  88                 :"=a" (ret),"=d" (x) \
  89                 :"c" (ptr) \
  90                 :"r8")
  91
  92 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
  93 #define get_user(x,ptr)                                                 \
  94 ({      unsigned long __val_gu;                                         \
  95         int __ret_gu;                                                   \
  96         __chk_user_ptr(ptr);                                            \
  97         switch(sizeof (*(ptr))) {                                       \
  98         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
  99         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 100         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 101         case 8:  __get_user_x(8,__ret_gu,__val_gu,ptr); break;          \
 102         default: __get_user_bad(); break;                               \
 103         }                                                               \
 104         (x) = (typeof(*(ptr)))__val_gu;                         \
 105         __ret_gu;                                                       \
 106 })
 107
 108 extern void __put_user_1(void);
 109 extern void __put_user_2(void);
 110 extern void __put_user_4(void);
 111 extern void __put_user_8(void);
 112 extern void __put_user_bad(void);
 113
 114 #define __put_user_x(size,ret,x,ptr)                                    \
 115         asm volatile("call __put_user_" #size                   \
 116                 :"=a" (ret)                                             \
 117                 :"c" (ptr),"d" (x)                                      \
 118                 :"r8")
 119
 120 #define put_user(x,ptr)                                                 \
 121   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 122
 123 #define __get_user(x,ptr) \
 124   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 125 #define __put_user(x,ptr) \
 126   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 127
 128 #define __get_user_unaligned __get_user
 129 #define __put_user_unaligned __put_user
 130
 131 #define __put_user_nocheck(x,ptr,size)                  \
 132 ({                                                      \
 133         int __pu_err;                                   \
 134         __put_user_size((x),(ptr),(size),__pu_err);     \
 135         __pu_err;                                       \
 136 })
 137
 138
 139 #define __put_user_check(x,ptr,size)                    \
 140 ({                                                      \
 141         int __pu_err;                                   \
 142         typeof(*(ptr)) __user *__pu_addr = (ptr);       \
 143         switch (size) {                                 \
 144         case 1: __put_user_x(1,__pu_err,x,__pu_addr); break;    \
 145         case 2: __put_user_x(2,__pu_err,x,__pu_addr); break;    \
 146         case 4: __put_user_x(4,__pu_err,x,__pu_addr); break;    \
 147         case 8: __put_user_x(8,__pu_err,x,__pu_addr); break;    \
 148         default: __put_user_bad();                      \
 149         }                                               \
 150         __pu_err;                                       \
 151 })
 152
 153 #define __put_user_size(x,ptr,size,retval)                              \
 154 do {                                                                    \
 155         retval = 0;                                                     \
 156         __chk_user_ptr(ptr);                                            \
 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 __user *)(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         unsigned 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_1(void);
 201 extern int __get_user_2(void);
 202 extern int __get_user_4(void);
 203 extern int __get_user_8(void);
 204 extern int __get_user_bad(void);
 205
 206 #define __get_user_size(x,ptr,size,retval)                              \
 207 do {                                                                    \
 208         retval = 0;                                                     \
 209         __chk_user_ptr(ptr);                                            \
 210         switch (size) {                                                 \
 211           case 1: __get_user_asm(x,ptr,retval,"b","b","=q",-EFAULT); break;\
 212           case 2: __get_user_asm(x,ptr,retval,"w","w","=r",-EFAULT); break;\
 213           case 4: __get_user_asm(x,ptr,retval,"l","k","=r",-EFAULT); break;\
 214           case 8: __get_user_asm(x,ptr,retval,"q","","=r",-EFAULT); break;\
 215           default: (x) = __get_user_bad();                              \
 216         }                                                               \
 217 } while (0)
 218
 219 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 220         asm volatile(                                   \
 221                 "1:     mov"itype" %2,%"rtype"1\n"              \
 222                 "2:\n"                                          \
 223                 ".section .fixup,\"ax\"\n"                      \
 224                 "3:     mov %3,%0\n"                            \
 225                 "       xor"itype" %"rtype"1,%"rtype"1\n"       \
 226                 "       jmp 2b\n"                               \
 227                 ".previous\n"                                   \
 228                 ".section __ex_table,\"a\"\n"                   \
 229                 "       .align 8\n"                             \
 230                 "       .quad 1b,3b\n"                          \
 231                 ".previous"                                     \
 232                 : "=r"(err), ltype (x)                          \
 233                 : "m"(__m(addr)), "i"(errno), "0"(err))
 234
 235 /*
 236  * Copy To/From Userspace
 237  */
 238
 239 /* Handles exceptions in both to and from, but doesn't do access_ok */
 240 __must_check unsigned long
 241 copy_user_generic(void *to, const void *from, unsigned len);
 242
 243 __must_check unsigned long
 244 copy_to_user(void __user *to, const void *from, unsigned len);
 245 __must_check unsigned long
 246 copy_from_user(void *to, const void __user *from, unsigned len);
 247 __must_check unsigned long
 248 copy_in_user(void __user *to, const void __user *from, unsigned len);
 249
 250 static __always_inline __must_check
 251 int __copy_from_user(void *dst, const void __user *src, unsigned size)
 252 {
 253         int ret = 0;
 254         if (!__builtin_constant_p(size))
 255                 return copy_user_generic(dst,(__force void *)src,size);
 256         switch (size) {
 257         case 1:__get_user_asm(*(u8*)dst,(u8 __user *)src,ret,"b","b","=q",1);
 258                 return ret;
 259         case 2:__get_user_asm(*(u16*)dst,(u16 __user *)src,ret,"w","w","=r",2);
 260                 return ret;
 261         case 4:__get_user_asm(*(u32*)dst,(u32 __user *)src,ret,"l","k","=r",4);
 262                 return ret;
 263         case 8:__get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",8);
 264                 return ret;
 265         case 10:
 266                 __get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",16);
 267                 if (unlikely(ret)) return ret;
 268                 __get_user_asm(*(u16*)(8+(char*)dst),(u16 __user *)(8+(char __user *)src),ret,"w","w","=r",2);
 269                 return ret;
 270         case 16:
 271                 __get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",16);
 272                 if (unlikely(ret)) return ret;
 273                 __get_user_asm(*(u64*)(8+(char*)dst),(u64 __user *)(8+(char __user *)src),ret,"q","","=r",8);
 274                 return ret;
 275         default:
 276                 return copy_user_generic(dst,(__force void *)src,size);
 277         }
 278 }
 279
 280 static __always_inline __must_check
 281 int __copy_to_user(void __user *dst, const void *src, unsigned size)
 282 {
 283         int ret = 0;
 284         if (!__builtin_constant_p(size))
 285                 return copy_user_generic((__force void *)dst,src,size);
 286         switch (size) {
 287         case 1:__put_user_asm(*(u8*)src,(u8 __user *)dst,ret,"b","b","iq",1);
 288                 return ret;
 289         case 2:__put_user_asm(*(u16*)src,(u16 __user *)dst,ret,"w","w","ir",2);
 290                 return ret;
 291         case 4:__put_user_asm(*(u32*)src,(u32 __user *)dst,ret,"l","k","ir",4);
 292                 return ret;
 293         case 8:__put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",8);
 294                 return ret;
 295         case 10:
 296                 __put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",10);
 297                 if (unlikely(ret)) return ret;
 298                 asm("":::"memory");
 299                 __put_user_asm(4[(u16*)src],4+(u16 __user *)dst,ret,"w","w","ir",2);
 300                 return ret;
 301         case 16:
 302                 __put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",16);
 303                 if (unlikely(ret)) return ret;
 304                 asm("":::"memory");
 305                 __put_user_asm(1[(u64*)src],1+(u64 __user *)dst,ret,"q","","ir",8);
 306                 return ret;
 307         default:
 308                 return copy_user_generic((__force void *)dst,src,size);
 309         }
 310 }
 311
 312 static __always_inline __must_check
 313 int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
 314 {
 315         int ret = 0;
 316         if (!__builtin_constant_p(size))
 317                 return copy_user_generic((__force void *)dst,(__force void *)src,size);
 318         switch (size) {
 319         case 1: {
 320                 u8 tmp;
 321                 __get_user_asm(tmp,(u8 __user *)src,ret,"b","b","=q",1);
 322                 if (likely(!ret))
 323                         __put_user_asm(tmp,(u8 __user *)dst,ret,"b","b","iq",1);
 324                 return ret;
 325         }
 326         case 2: {
 327                 u16 tmp;
 328                 __get_user_asm(tmp,(u16 __user *)src,ret,"w","w","=r",2);
 329                 if (likely(!ret))
 330                         __put_user_asm(tmp,(u16 __user *)dst,ret,"w","w","ir",2);
 331                 return ret;
 332         }
 333
 334         case 4: {
 335                 u32 tmp;
 336                 __get_user_asm(tmp,(u32 __user *)src,ret,"l","k","=r",4);
 337                 if (likely(!ret))
 338                         __put_user_asm(tmp,(u32 __user *)dst,ret,"l","k","ir",4);
 339                 return ret;
 340         }
 341         case 8: {
 342                 u64 tmp;
 343                 __get_user_asm(tmp,(u64 __user *)src,ret,"q","","=r",8);
 344                 if (likely(!ret))
 345                         __put_user_asm(tmp,(u64 __user *)dst,ret,"q","","ir",8);
 346                 return ret;
 347         }
 348         default:
 349                 return copy_user_generic((__force void *)dst,(__force void *)src,size);
 350         }
 351 }
 352
 353 __must_check long
 354 strncpy_from_user(char *dst, const char __user *src, long count);
 355 __must_check long
 356 __strncpy_from_user(char *dst, const char __user *src, long count);
 357 __must_check long strnlen_user(const char __user *str, long n);
 358 __must_check long __strnlen_user(const char __user *str, long n);
 359 __must_check long strlen_user(const char __user *str);
 360 __must_check unsigned long clear_user(void __user *mem, unsigned long len);
 361 __must_check unsigned long __clear_user(void __user *mem, unsigned long len);
 362
 363 __must_check long __copy_from_user_inatomic(void *dst, const void __user *src, unsigned size);
 364
 365 static __must_check __always_inline int
 366 __copy_to_user_inatomic(void __user *dst, const void *src, unsigned size)
 367 {
 368         return copy_user_generic((__force void *)dst, src, size);
 369 }
 370
 371 #endif /* __X86_64_UACCESS_H */