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(0xFFFFFFFFFFFFFFFFUL)
  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         __chk_user_ptr(addr); \
  44         asm("# range_ok\n\r" \
  45                 "addq %3,%1 ; sbbq %0,%0 ; cmpq %1,%4 ; sbbq $0,%0"  \
  46                 :"=&r" (flag), "=r" (sum) \
  47                 :"1" (addr),"g" ((long)(size)),"g" (current_thread_info()->addr_limit.seg)); \
  48         flag; })
  49
  50 #define access_ok(type, addr, size) (__range_not_ok(addr,size) == 0)
  51
  52 extern inline int verify_area(int type, const void __user * addr, unsigned long size)
  53 {
  54         return access_ok(type,addr,size) ? 0 : -EFAULT;
  55 }
  56
  57
  58 /*
  59  * The exception table consists of pairs of addresses: the first is the
  60  * address of an instruction that is allowed to fault, and the second is
  61  * the address at which the program should continue.  No registers are
  62  * modified, so it is entirely up to the continuation code to figure out
  63  * what to do.
  64  *
  65  * All the routines below use bits of fixup code that are out of line
  66  * with the main instruction path.  This means when everything is well,
  67  * we don't even have to jump over them.  Further, they do not intrude
  68  * on our cache or tlb entries.
  69  */
  70
  71 struct exception_table_entry
  72 {
  73         unsigned long insn, fixup;
  74 };
  75
  76
  77 /*
  78  * These are the main single-value transfer routines.  They automatically
  79  * use the right size if we just have the right pointer type.
  80  *
  81  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  82  * and yet we don't want to do any pointers, because that is too much
  83  * of a performance impact. Thus we have a few rather ugly macros here,
  84  * and hide all the ugliness from the user.
  85  *
  86  * The "__xxx" versions of the user access functions are versions that
  87  * do not verify the address space, that must have been done previously
  88  * with a separate "access_ok()" call (this is used when we do multiple
  89  * accesses to the same area of user memory).
  90  */
  91
  92 extern void __get_user_1(void);
  93 extern void __get_user_2(void);
  94 extern void __get_user_4(void);
  95 extern void __get_user_8(void);
  96
  97 #define __get_user_x(size,ret,x,ptr) \
  98         __asm__ __volatile__("call __get_user_" #size \
  99                 :"=a" (ret),"=d" (x) \
 100                 :"0" (ptr) \
 101                 :"rbx")
 102
 103 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
 104 #define get_user(x,ptr)                                                 \
 105 ({      long __val_gu;                                                  \
 106         int __ret_gu;                                                   \
 107         __chk_user_ptr(ptr);                                            \
 108         switch(sizeof (*(ptr))) {                                       \
 109         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
 110         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 111         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 112         case 8:  __get_user_x(8,__ret_gu,__val_gu,ptr); break;          \
 113         default: __get_user_bad(); break;                               \
 114         }                                                               \
 115         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 116         __ret_gu;                                                       \
 117 })
 118
 119 extern void __put_user_1(void);
 120 extern void __put_user_2(void);
 121 extern void __put_user_4(void);
 122 extern void __put_user_8(void);
 123
 124 extern void __put_user_bad(void);
 125
 126 #define __put_user_x(size,ret,x,ptr)                                    \
 127         __asm__ __volatile__("call __put_user_" #size                   \
 128                 :"=a" (ret)                                             \
 129                 :"0" (ptr),"d" (x)                                      \
 130                 :"rbx")
 131
 132 #define put_user(x,ptr)                                                 \
 133   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 134
 135 #define __get_user(x,ptr) \
 136   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 137 #define __put_user(x,ptr) \
 138   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 139
 140 #define __put_user_nocheck(x,ptr,size)                  \
 141 ({                                                      \
 142         int __pu_err;                                   \
 143         __put_user_size((x),(ptr),(size),__pu_err);     \
 144         __pu_err;                                       \
 145 })
 146
 147
 148 #define __put_user_check(x,ptr,size)                    \
 149 ({                                                      \
 150         int __pu_err = -EFAULT;                         \
 151         __typeof__(*(ptr)) __user *__pu_addr = (ptr);   \
 152         if (likely(access_ok(VERIFY_WRITE,__pu_addr,size)))     \
 153                 __put_user_size((x),__pu_addr,(size),__pu_err); \
 154         __pu_err;                                       \
 155 })
 156
 157 #define __put_user_size(x,ptr,size,retval)                              \
 158 do {                                                                    \
 159         retval = 0;                                                     \
 160         __chk_user_ptr(ptr);                                            \
 161         switch (size) {                                                 \
 162           case 1: __put_user_asm(x,ptr,retval,"b","b","iq",-EFAULT); break;\
 163           case 2: __put_user_asm(x,ptr,retval,"w","w","ir",-EFAULT); break;\
 164           case 4: __put_user_asm(x,ptr,retval,"l","k","ir",-EFAULT); break;\
 165           case 8: __put_user_asm(x,ptr,retval,"q","","ir",-EFAULT); break;\
 166           default: __put_user_bad();                                    \
 167         }                                                               \
 168 } while (0)
 169
 170 /* FIXME: this hack is definitely wrong -AK */
 171 struct __large_struct { unsigned long buf[100]; };
 172 #define __m(x) (*(struct __large_struct *)(x))
 173
 174 /*
 175  * Tell gcc we read from memory instead of writing: this is because
 176  * we do not write to any memory gcc knows about, so there are no
 177  * aliasing issues.
 178  */
 179 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errno)        \
 180         __asm__ __volatile__(                                   \
 181                 "1:     mov"itype" %"rtype"1,%2\n"              \
 182                 "2:\n"                                          \
 183                 ".section .fixup,\"ax\"\n"                      \
 184                 "3:     mov %3,%0\n"                            \
 185                 "       jmp 2b\n"                               \
 186                 ".previous\n"                                   \
 187                 ".section __ex_table,\"a\"\n"                   \
 188                 "       .align 8\n"                             \
 189                 "       .quad 1b,3b\n"                          \
 190                 ".previous"                                     \
 191                 : "=r"(err)                                     \
 192                 : ltype (x), "m"(__m(addr)), "i"(errno), "0"(err))
 193
 194
 195 #define __get_user_nocheck(x,ptr,size)                          \
 196 ({                                                              \
 197         int __gu_err;                                           \
 198         long __gu_val;                                          \
 199         __get_user_size(__gu_val,(ptr),(size),__gu_err);        \
 200         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 201         __gu_err;                                               \
 202 })
 203
 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 extern unsigned long copy_user_generic(void *to, const void *from, unsigned len);
 241
 242 extern unsigned long copy_to_user(void __user *to, const void *from, unsigned len);
 243 extern unsigned long copy_from_user(void *to, const void __user *from, unsigned len);
 244 extern unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len);
 245
 246 static inline int __copy_from_user(void *dst, const void __user *src, unsigned size)
 247 {
 248        int ret = 0;
 249         if (!__builtin_constant_p(size))
 250                 return copy_user_generic(dst,(__force void *)src,size);
 251         switch (size) {
 252         case 1:__get_user_asm(*(u8*)dst,(u8 __user *)src,ret,"b","b","=q",1);
 253                 return ret;
 254         case 2:__get_user_asm(*(u16*)dst,(u16 __user *)src,ret,"w","w","=r",2);
 255                 return ret;
 256         case 4:__get_user_asm(*(u32*)dst,(u32 __user *)src,ret,"l","k","=r",4);
 257                 return ret;
 258         case 8:__get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",8);
 259                 return ret;
 260         case 10:
 261                 __get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",16);
 262                 if (unlikely(ret)) return ret;
 263                 __get_user_asm(*(u16*)(8+(char*)dst),(u16 __user *)(8+(char __user *)src),ret,"w","w","=r",2);
 264                 return ret;
 265         case 16:
 266                 __get_user_asm(*(u64*)dst,(u64 __user *)src,ret,"q","","=r",16);
 267                 if (unlikely(ret)) return ret;
 268                 __get_user_asm(*(u64*)(8+(char*)dst),(u64 __user *)(8+(char __user *)src),ret,"q","","=r",8);
 269                 return ret;
 270         default:
 271                 return copy_user_generic(dst,(__force void *)src,size);
 272         }
 273 }
 274
 275 static inline int __copy_to_user(void __user *dst, const void *src, unsigned size)
 276 {
 277        int ret = 0;
 278         if (!__builtin_constant_p(size))
 279                 return copy_user_generic((__force void *)dst,src,size);
 280         switch (size) {
 281         case 1:__put_user_asm(*(u8*)src,(u8 __user *)dst,ret,"b","b","iq",1);
 282                 return ret;
 283         case 2:__put_user_asm(*(u16*)src,(u16 __user *)dst,ret,"w","w","ir",2);
 284                 return ret;
 285         case 4:__put_user_asm(*(u32*)src,(u32 __user *)dst,ret,"l","k","ir",4);
 286                 return ret;
 287         case 8:__put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",8);
 288                 return ret;
 289         case 10:
 290                 __put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",10);
 291                 if (unlikely(ret)) return ret;
 292                 asm("":::"memory");
 293                 __put_user_asm(4[(u16*)src],4+(u16 __user *)dst,ret,"w","w","ir",2);
 294                 return ret;
 295         case 16:
 296                 __put_user_asm(*(u64*)src,(u64 __user *)dst,ret,"q","","ir",16);
 297                 if (unlikely(ret)) return ret;
 298                 asm("":::"memory");
 299                 __put_user_asm(1[(u64*)src],1+(u64 __user *)dst,ret,"q","","ir",8);
 300                 return ret;
 301         default:
 302                 return copy_user_generic((__force void *)dst,src,size);
 303         }
 304 }
 305
 306
 307 static inline int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
 308 {
 309        int ret = 0;
 310         if (!__builtin_constant_p(size))
 311                 return copy_user_generic((__force void *)dst,(__force void *)src,size);
 312         switch (size) {
 313         case 1: {
 314                 u8 tmp;
 315                 __get_user_asm(tmp,(u8 __user *)src,ret,"b","b","=q",1);
 316                 if (likely(!ret))
 317                         __put_user_asm(tmp,(u8 __user *)dst,ret,"b","b","iq",1);
 318                 return ret;
 319         }
 320         case 2: {
 321                 u16 tmp;
 322                 __get_user_asm(tmp,(u16 __user *)src,ret,"w","w","=r",2);
 323                 if (likely(!ret))
 324                         __put_user_asm(tmp,(u16 __user *)dst,ret,"w","w","ir",2);
 325                 return ret;
 326         }
 327
 328         case 4: {
 329                 u32 tmp;
 330                 __get_user_asm(tmp,(u32 __user *)src,ret,"l","k","=r",4);
 331                 if (likely(!ret))
 332                         __put_user_asm(tmp,(u32 __user *)dst,ret,"l","k","ir",4);
 333                 return ret;
 334         }
 335         case 8: {
 336                 u64 tmp;
 337                 __get_user_asm(tmp,(u64 __user *)src,ret,"q","","=r",8);
 338                 if (likely(!ret))
 339                         __put_user_asm(tmp,(u64 __user *)dst,ret,"q","","ir",8);
 340                 return ret;
 341         }
 342         default:
 343                 return copy_user_generic((__force void *)dst,(__force void *)src,size);
 344         }
 345 }
 346
 347 long strncpy_from_user(char *dst, const char __user *src, long count);
 348 long __strncpy_from_user(char *dst, const char __user *src, long count);
 349 long strnlen_user(const char __user *str, long n);
 350 long strlen_user(const char __user *str);
 351 unsigned long clear_user(void __user *mem, unsigned long len);
 352 unsigned long __clear_user(void __user *mem, unsigned long len);
 353
 354 #endif /* __X86_64_UACCESS_H */