arch/arm/include/asm/uaccess.h

   1 /*
   2  *  arch/arm/include/asm/uaccess.h
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #ifndef _ASMARM_UACCESS_H
   9 #define _ASMARM_UACCESS_H
  10
  11 /*
  12  * User space memory access functions
  13  */
  14 #include <linux/string.h>
  15 #include <linux/thread_info.h>
  16 #include <asm/errno.h>
  17 #include <asm/memory.h>
  18 #include <asm/domain.h>
  19 #include <asm/unified.h>
  20 #include <asm/compiler.h>
  21
  22 #define VERIFY_READ 0
  23 #define VERIFY_WRITE 1
  24
  25 /*
  26  * The exception table consists of pairs of addresses: the first is the
  27  * address of an instruction that is allowed to fault, and the second is
  28  * the address at which the program should continue.  No registers are
  29  * modified, so it is entirely up to the continuation code to figure out
  30  * what to do.
  31  *
  32  * All the routines below use bits of fixup code that are out of line
  33  * with the main instruction path.  This means when everything is well,
  34  * we don't even have to jump over them.  Further, they do not intrude
  35  * on our cache or tlb entries.
  36  */
  37
  38 struct exception_table_entry
  39 {
  40         unsigned long insn, fixup;
  41 };
  42
  43 extern int fixup_exception(struct pt_regs *regs);
  44
  45 /*
  46  * These two are intentionally not defined anywhere - if the kernel
  47  * code generates any references to them, that's a bug.
  48  */
  49 extern int __get_user_bad(void);
  50 extern int __put_user_bad(void);
  51
  52 /*
  53  * Note that this is actually 0x1,0000,0000
  54  */
  55 #define KERNEL_DS       0x00000000
  56 #define get_ds()        (KERNEL_DS)
  57
  58 #ifdef CONFIG_MMU
  59
  60 #define USER_DS         TASK_SIZE
  61 #define get_fs()        (current_thread_info()->addr_limit)
  62
  63 static inline void set_fs(mm_segment_t fs)
  64 {
  65         current_thread_info()->addr_limit = fs;
  66         modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
  67 }
  68
  69 #define segment_eq(a,b) ((a) == (b))
  70
  71 #define __addr_ok(addr) ({ \
  72         unsigned long flag; \
  73         __asm__("cmp %2, %0; movlo %0, #0" \
  74                 : "=&r" (flag) \
  75                 : "0" (current_thread_info()->addr_limit), "r" (addr) \
  76                 : "cc"); \
  77         (flag == 0); })
  78
  79 /* We use 33-bit arithmetic here... */
  80 #define __range_ok(addr,size) ({ \
  81         unsigned long flag, roksum; \
  82         __chk_user_ptr(addr);   \
  83         __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
  84                 : "=&r" (flag), "=&r" (roksum) \
  85                 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
  86                 : "cc"); \
  87         flag; })
  88
  89 /*
  90  * Single-value transfer routines.  They automatically use the right
  91  * size if we just have the right pointer type.  Note that the functions
  92  * which read from user space (*get_*) need to take care not to leak
  93  * kernel data even if the calling code is buggy and fails to check
  94  * the return value.  This means zeroing out the destination variable
  95  * or buffer on error.  Normally this is done out of line by the
  96  * fixup code, but there are a few places where it intrudes on the
  97  * main code path.  When we only write to user space, there is no
  98  * problem.
  99  */
 100 extern int __get_user_1(void *);
 101 extern int __get_user_2(void *);
 102 extern int __get_user_4(void *);
 103
 104 #define __GUP_CLOBBER_1 "lr", "cc"
 105 #ifdef CONFIG_CPU_USE_DOMAINS
 106 #define __GUP_CLOBBER_2 "ip", "lr", "cc"
 107 #else
 108 #define __GUP_CLOBBER_2 "lr", "cc"
 109 #endif
 110 #define __GUP_CLOBBER_4 "lr", "cc"
 111
 112 #define __get_user_x(__r2,__p,__e,__l,__s)                              \
 113            __asm__ __volatile__ (                                       \
 114                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 115                 __asmeq("%3", "r1")                                     \
 116                 "bl     __get_user_" #__s                               \
 117                 : "=&r" (__e), "=r" (__r2)                              \
 118                 : "0" (__p), "r" (__l)                                  \
 119                 : __GUP_CLOBBER_##__s)
 120
 121 #define __get_user_check(x,p)                                                   \
 122         ({                                                              \
 123                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 124                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 125                 register unsigned long __r2 asm("r2");                  \
 126                 register unsigned long __l asm("r1") = __limit;         \
 127                 register int __e asm("r0");                             \
 128                 switch (sizeof(*(__p))) {                               \
 129                 case 1:                                                 \
 130                         __get_user_x(__r2, __p, __e, __l, 1);           \
 131                         break;                                          \
 132                 case 2:                                                 \
 133                         __get_user_x(__r2, __p, __e, __l, 2);           \
 134                         break;                                          \
 135                 case 4:                                                 \
 136                         __get_user_x(__r2, __p, __e, __l, 4);           \
 137                         break;                                          \
 138                 default: __e = __get_user_bad(); break;                 \
 139                 }                                                       \
 140                 x = (typeof(*(p))) __r2;                                \
 141                 __e;                                                    \
 142         })
 143
 144 #define get_user(x,p)                                                   \
 145         ({                                                              \
 146                 might_fault();                                          \
 147                 __get_user_check(x,p);                                  \
 148          })
 149
 150 extern int __put_user_1(void *, unsigned int);
 151 extern int __put_user_2(void *, unsigned int);
 152 extern int __put_user_4(void *, unsigned int);
 153 extern int __put_user_8(void *, unsigned long long);
 154
 155 #define __put_user_x(__r2,__p,__e,__l,__s)                              \
 156            __asm__ __volatile__ (                                       \
 157                 __asmeq("%0", "r0") __asmeq("%2", "r2")                 \
 158                 __asmeq("%3", "r1")                                     \
 159                 "bl     __put_user_" #__s                               \
 160                 : "=&r" (__e)                                           \
 161                 : "0" (__p), "r" (__r2), "r" (__l)                      \
 162                 : "ip", "lr", "cc")
 163
 164 #define __put_user_check(x,p)                                                   \
 165         ({                                                              \
 166                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 167                 const typeof(*(p)) __user *__tmp_p = (p);               \
 168                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
 169                 register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
 170                 register unsigned long __l asm("r1") = __limit;         \
 171                 register int __e asm("r0");                             \
 172                 switch (sizeof(*(__p))) {                               \
 173                 case 1:                                                 \
 174                         __put_user_x(__r2, __p, __e, __l, 1);           \
 175                         break;                                          \
 176                 case 2:                                                 \
 177                         __put_user_x(__r2, __p, __e, __l, 2);           \
 178                         break;                                          \
 179                 case 4:                                                 \
 180                         __put_user_x(__r2, __p, __e, __l, 4);           \
 181                         break;                                          \
 182                 case 8:                                                 \
 183                         __put_user_x(__r2, __p, __e, __l, 8);           \
 184                         break;                                          \
 185                 default: __e = __put_user_bad(); break;                 \
 186                 }                                                       \
 187                 __e;                                                    \
 188         })
 189
 190 #define put_user(x,p)                                                   \
 191         ({                                                              \
 192                 might_fault();                                          \
 193                 __put_user_check(x,p);                                  \
 194          })
 195
 196 #else /* CONFIG_MMU */
 197
 198 /*
 199  * uClinux has only one addr space, so has simplified address limits.
 200  */
 201 #define USER_DS                 KERNEL_DS
 202
 203 #define segment_eq(a,b)         (1)
 204 #define __addr_ok(addr)         ((void)(addr),1)
 205 #define __range_ok(addr,size)   ((void)(addr),0)
 206 #define get_fs()                (KERNEL_DS)
 207
 208 static inline void set_fs(mm_segment_t fs)
 209 {
 210 }
 211
 212 #define get_user(x,p)   __get_user(x,p)
 213 #define put_user(x,p)   __put_user(x,p)
 214
 215 #endif /* CONFIG_MMU */
 216
 217 #define access_ok(type,addr,size)       (__range_ok(addr,size) == 0)
 218
 219 #define user_addr_max() \
 220         (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
 221
 222 /*
 223  * The "__xxx" versions of the user access functions do not verify the
 224  * address space - it must have been done previously with a separate
 225  * "access_ok()" call.
 226  *
 227  * The "xxx_error" versions set the third argument to EFAULT if an
 228  * error occurs, and leave it unchanged on success.  Note that these
 229  * versions are void (ie, don't return a value as such).
 230  */
 231 #define __get_user(x,ptr)                                               \
 232 ({                                                                      \
 233         long __gu_err = 0;                                              \
 234         __get_user_err((x),(ptr),__gu_err);                             \
 235         __gu_err;                                                       \
 236 })
 237
 238 #define __get_user_error(x,ptr,err)                                     \
 239 ({                                                                      \
 240         __get_user_err((x),(ptr),err);                                  \
 241         (void) 0;                                                       \
 242 })
 243
 244 #define __get_user_err(x,ptr,err)                                       \
 245 do {                                                                    \
 246         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 247         unsigned long __gu_val;                                         \
 248         __chk_user_ptr(ptr);                                            \
 249         might_fault();                                                  \
 250         switch (sizeof(*(ptr))) {                                       \
 251         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
 252         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
 253         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
 254         default: (__gu_val) = __get_user_bad();                         \
 255         }                                                               \
 256         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 257 } while (0)
 258
 259 #define __get_user_asm_byte(x,addr,err)                         \
 260         __asm__ __volatile__(                                   \
 261         "1:     " TUSER(ldrb) " %1,[%2],#0\n"                   \
 262         "2:\n"                                                  \
 263         "       .pushsection .fixup,\"ax\"\n"                   \
 264         "       .align  2\n"                                    \
 265         "3:     mov     %0, %3\n"                               \
 266         "       mov     %1, #0\n"                               \
 267         "       b       2b\n"                                   \
 268         "       .popsection\n"                                  \
 269         "       .pushsection __ex_table,\"a\"\n"                \
 270         "       .align  3\n"                                    \
 271         "       .long   1b, 3b\n"                               \
 272         "       .popsection"                                    \
 273         : "+r" (err), "=&r" (x)                                 \
 274         : "r" (addr), "i" (-EFAULT)                             \
 275         : "cc")
 276
 277 #ifndef __ARMEB__
 278 #define __get_user_asm_half(x,__gu_addr,err)                    \
 279 ({                                                              \
 280         unsigned long __b1, __b2;                               \
 281         __get_user_asm_byte(__b1, __gu_addr, err);              \
 282         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 283         (x) = __b1 | (__b2 << 8);                               \
 284 })
 285 #else
 286 #define __get_user_asm_half(x,__gu_addr,err)                    \
 287 ({                                                              \
 288         unsigned long __b1, __b2;                               \
 289         __get_user_asm_byte(__b1, __gu_addr, err);              \
 290         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 291         (x) = (__b1 << 8) | __b2;                               \
 292 })
 293 #endif
 294
 295 #define __get_user_asm_word(x,addr,err)                         \
 296         __asm__ __volatile__(                                   \
 297         "1:     " TUSER(ldr) "  %1,[%2],#0\n"                   \
 298         "2:\n"                                                  \
 299         "       .pushsection .fixup,\"ax\"\n"                   \
 300         "       .align  2\n"                                    \
 301         "3:     mov     %0, %3\n"                               \
 302         "       mov     %1, #0\n"                               \
 303         "       b       2b\n"                                   \
 304         "       .popsection\n"                                  \
 305         "       .pushsection __ex_table,\"a\"\n"                \
 306         "       .align  3\n"                                    \
 307         "       .long   1b, 3b\n"                               \
 308         "       .popsection"                                    \
 309         : "+r" (err), "=&r" (x)                                 \
 310         : "r" (addr), "i" (-EFAULT)                             \
 311         : "cc")
 312
 313 #define __put_user(x,ptr)                                               \
 314 ({                                                                      \
 315         long __pu_err = 0;                                              \
 316         __put_user_err((x),(ptr),__pu_err);                             \
 317         __pu_err;                                                       \
 318 })
 319
 320 #define __put_user_error(x,ptr,err)                                     \
 321 ({                                                                      \
 322         __put_user_err((x),(ptr),err);                                  \
 323         (void) 0;                                                       \
 324 })
 325
 326 #define __put_user_err(x,ptr,err)                                       \
 327 do {                                                                    \
 328         unsigned long __pu_addr = (unsigned long)(ptr);                 \
 329         __typeof__(*(ptr)) __pu_val = (x);                              \
 330         __chk_user_ptr(ptr);                                            \
 331         might_fault();                                                  \
 332         switch (sizeof(*(ptr))) {                                       \
 333         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
 334         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
 335         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
 336         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
 337         default: __put_user_bad();                                      \
 338         }                                                               \
 339 } while (0)
 340
 341 #define __put_user_asm_byte(x,__pu_addr,err)                    \
 342         __asm__ __volatile__(                                   \
 343         "1:     " TUSER(strb) " %1,[%2],#0\n"                   \
 344         "2:\n"                                                  \
 345         "       .pushsection .fixup,\"ax\"\n"                   \
 346         "       .align  2\n"                                    \
 347         "3:     mov     %0, %3\n"                               \
 348         "       b       2b\n"                                   \
 349         "       .popsection\n"                                  \
 350         "       .pushsection __ex_table,\"a\"\n"                \
 351         "       .align  3\n"                                    \
 352         "       .long   1b, 3b\n"                               \
 353         "       .popsection"                                    \
 354         : "+r" (err)                                            \
 355         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 356         : "cc")
 357
 358 #ifndef __ARMEB__
 359 #define __put_user_asm_half(x,__pu_addr,err)                    \
 360 ({                                                              \
 361         unsigned long __temp = (unsigned long)(x);              \
 362         __put_user_asm_byte(__temp, __pu_addr, err);            \
 363         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 364 })
 365 #else
 366 #define __put_user_asm_half(x,__pu_addr,err)                    \
 367 ({                                                              \
 368         unsigned long __temp = (unsigned long)(x);              \
 369         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 370         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 371 })
 372 #endif
 373
 374 #define __put_user_asm_word(x,__pu_addr,err)                    \
 375         __asm__ __volatile__(                                   \
 376         "1:     " TUSER(str) "  %1,[%2],#0\n"                   \
 377         "2:\n"                                                  \
 378         "       .pushsection .fixup,\"ax\"\n"                   \
 379         "       .align  2\n"                                    \
 380         "3:     mov     %0, %3\n"                               \
 381         "       b       2b\n"                                   \
 382         "       .popsection\n"                                  \
 383         "       .pushsection __ex_table,\"a\"\n"                \
 384         "       .align  3\n"                                    \
 385         "       .long   1b, 3b\n"                               \
 386         "       .popsection"                                    \
 387         : "+r" (err)                                            \
 388         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 389         : "cc")
 390
 391 #ifndef __ARMEB__
 392 #define __reg_oper0     "%R2"
 393 #define __reg_oper1     "%Q2"
 394 #else
 395 #define __reg_oper0     "%Q2"
 396 #define __reg_oper1     "%R2"
 397 #endif
 398
 399 #define __put_user_asm_dword(x,__pu_addr,err)                   \
 400         __asm__ __volatile__(                                   \
 401  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 402  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 403  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 404  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 405         "3:\n"                                                  \
 406         "       .pushsection .fixup,\"ax\"\n"                   \
 407         "       .align  2\n"                                    \
 408         "4:     mov     %0, %3\n"                               \
 409         "       b       3b\n"                                   \
 410         "       .popsection\n"                                  \
 411         "       .pushsection __ex_table,\"a\"\n"                \
 412         "       .align  3\n"                                    \
 413         "       .long   1b, 4b\n"                               \
 414         "       .long   2b, 4b\n"                               \
 415         "       .popsection"                                    \
 416         : "+r" (err), "+r" (__pu_addr)                          \
 417         : "r" (x), "i" (-EFAULT)                                \
 418         : "cc")
 419
 420
 421 #ifdef CONFIG_MMU
 422 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 423 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 424 extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 425 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 426 extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
 427 #else
 428 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
 429 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
 430 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
 431 #endif
 432
 433 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 434 {
 435         if (access_ok(VERIFY_READ, from, n))
 436                 n = __copy_from_user(to, from, n);
 437         else /* security hole - plug it */
 438                 memset(to, 0, n);
 439         return n;
 440 }
 441
 442 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 443 {
 444         if (access_ok(VERIFY_WRITE, to, n))
 445                 n = __copy_to_user(to, from, n);
 446         return n;
 447 }
 448
 449 #define __copy_to_user_inatomic __copy_to_user
 450 #define __copy_from_user_inatomic __copy_from_user
 451
 452 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 453 {
 454         if (access_ok(VERIFY_WRITE, to, n))
 455                 n = __clear_user(to, n);
 456         return n;
 457 }
 458
 459 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 460
 461 extern __must_check long strlen_user(const char __user *str);
 462 extern __must_check long strnlen_user(const char __user *str, long n);
 463
 464 #endif /* _ASMARM_UACCESS_H */