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/system.h>
  20 #include <asm/unified.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(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 extern int __put_user_1(void *, unsigned int);
 145 extern int __put_user_2(void *, unsigned int);
 146 extern int __put_user_4(void *, unsigned int);
 147 extern int __put_user_8(void *, unsigned long long);
 148
 149 #define __put_user_x(__r2,__p,__e,__l,__s)                              \
 150            __asm__ __volatile__ (                                       \
 151                 __asmeq("%0", "r0") __asmeq("%2", "r2")                 \
 152                 __asmeq("%3", "r1")                                     \
 153                 "bl     __put_user_" #__s                               \
 154                 : "=&r" (__e)                                           \
 155                 : "0" (__p), "r" (__r2), "r" (__l)                      \
 156                 : "ip", "lr", "cc")
 157
 158 #define put_user(x,p)                                                   \
 159         ({                                                              \
 160                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
 161                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
 162                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 163                 register unsigned long __l asm("r1") = __limit;         \
 164                 register int __e asm("r0");                             \
 165                 switch (sizeof(*(__p))) {                               \
 166                 case 1:                                                 \
 167                         __put_user_x(__r2, __p, __e, __l, 1);           \
 168                         break;                                          \
 169                 case 2:                                                 \
 170                         __put_user_x(__r2, __p, __e, __l, 2);           \
 171                         break;                                          \
 172                 case 4:                                                 \
 173                         __put_user_x(__r2, __p, __e, __l, 4);           \
 174                         break;                                          \
 175                 case 8:                                                 \
 176                         __put_user_x(__r2, __p, __e, __l, 8);           \
 177                         break;                                          \
 178                 default: __e = __put_user_bad(); break;                 \
 179                 }                                                       \
 180                 __e;                                                    \
 181         })
 182
 183 #else /* CONFIG_MMU */
 184
 185 /*
 186  * uClinux has only one addr space, so has simplified address limits.
 187  */
 188 #define USER_DS                 KERNEL_DS
 189
 190 #define segment_eq(a,b)         (1)
 191 #define __addr_ok(addr)         (1)
 192 #define __range_ok(addr,size)   (0)
 193 #define get_fs()                (KERNEL_DS)
 194
 195 static inline void set_fs(mm_segment_t fs)
 196 {
 197 }
 198
 199 #define get_user(x,p)   __get_user(x,p)
 200 #define put_user(x,p)   __put_user(x,p)
 201
 202 #endif /* CONFIG_MMU */
 203
 204 #define access_ok(type,addr,size)       (__range_ok(addr,size) == 0)
 205
 206 /*
 207  * The "__xxx" versions of the user access functions do not verify the
 208  * address space - it must have been done previously with a separate
 209  * "access_ok()" call.
 210  *
 211  * The "xxx_error" versions set the third argument to EFAULT if an
 212  * error occurs, and leave it unchanged on success.  Note that these
 213  * versions are void (ie, don't return a value as such).
 214  */
 215 #define __get_user(x,ptr)                                               \
 216 ({                                                                      \
 217         long __gu_err = 0;                                              \
 218         __get_user_err((x),(ptr),__gu_err);                             \
 219         __gu_err;                                                       \
 220 })
 221
 222 #define __get_user_error(x,ptr,err)                                     \
 223 ({                                                                      \
 224         __get_user_err((x),(ptr),err);                                  \
 225         (void) 0;                                                       \
 226 })
 227
 228 #define __get_user_err(x,ptr,err)                                       \
 229 do {                                                                    \
 230         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 231         unsigned long __gu_val;                                         \
 232         __chk_user_ptr(ptr);                                            \
 233         switch (sizeof(*(ptr))) {                                       \
 234         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
 235         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
 236         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
 237         default: (__gu_val) = __get_user_bad();                         \
 238         }                                                               \
 239         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 240 } while (0)
 241
 242 #define __get_user_asm_byte(x,addr,err)                         \
 243         __asm__ __volatile__(                                   \
 244         "1:     " T(ldrb) "     %1,[%2],#0\n"                   \
 245         "2:\n"                                                  \
 246         "       .pushsection .fixup,\"ax\"\n"                   \
 247         "       .align  2\n"                                    \
 248         "3:     mov     %0, %3\n"                               \
 249         "       mov     %1, #0\n"                               \
 250         "       b       2b\n"                                   \
 251         "       .popsection\n"                                  \
 252         "       .pushsection __ex_table,\"a\"\n"                \
 253         "       .align  3\n"                                    \
 254         "       .long   1b, 3b\n"                               \
 255         "       .popsection"                                    \
 256         : "+r" (err), "=&r" (x)                                 \
 257         : "r" (addr), "i" (-EFAULT)                             \
 258         : "cc")
 259
 260 #ifndef __ARMEB__
 261 #define __get_user_asm_half(x,__gu_addr,err)                    \
 262 ({                                                              \
 263         unsigned long __b1, __b2;                               \
 264         __get_user_asm_byte(__b1, __gu_addr, err);              \
 265         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 266         (x) = __b1 | (__b2 << 8);                               \
 267 })
 268 #else
 269 #define __get_user_asm_half(x,__gu_addr,err)                    \
 270 ({                                                              \
 271         unsigned long __b1, __b2;                               \
 272         __get_user_asm_byte(__b1, __gu_addr, err);              \
 273         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 274         (x) = (__b1 << 8) | __b2;                               \
 275 })
 276 #endif
 277
 278 #define __get_user_asm_word(x,addr,err)                         \
 279         __asm__ __volatile__(                                   \
 280         "1:     " T(ldr) "      %1,[%2],#0\n"                   \
 281         "2:\n"                                                  \
 282         "       .pushsection .fixup,\"ax\"\n"                   \
 283         "       .align  2\n"                                    \
 284         "3:     mov     %0, %3\n"                               \
 285         "       mov     %1, #0\n"                               \
 286         "       b       2b\n"                                   \
 287         "       .popsection\n"                                  \
 288         "       .pushsection __ex_table,\"a\"\n"                \
 289         "       .align  3\n"                                    \
 290         "       .long   1b, 3b\n"                               \
 291         "       .popsection"                                    \
 292         : "+r" (err), "=&r" (x)                                 \
 293         : "r" (addr), "i" (-EFAULT)                             \
 294         : "cc")
 295
 296 #define __put_user(x,ptr)                                               \
 297 ({                                                                      \
 298         long __pu_err = 0;                                              \
 299         __put_user_err((x),(ptr),__pu_err);                             \
 300         __pu_err;                                                       \
 301 })
 302
 303 #define __put_user_error(x,ptr,err)                                     \
 304 ({                                                                      \
 305         __put_user_err((x),(ptr),err);                                  \
 306         (void) 0;                                                       \
 307 })
 308
 309 #define __put_user_err(x,ptr,err)                                       \
 310 do {                                                                    \
 311         unsigned long __pu_addr = (unsigned long)(ptr);                 \
 312         __typeof__(*(ptr)) __pu_val = (x);                              \
 313         __chk_user_ptr(ptr);                                            \
 314         switch (sizeof(*(ptr))) {                                       \
 315         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
 316         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
 317         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
 318         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
 319         default: __put_user_bad();                                      \
 320         }                                                               \
 321 } while (0)
 322
 323 #define __put_user_asm_byte(x,__pu_addr,err)                    \
 324         __asm__ __volatile__(                                   \
 325         "1:     " T(strb) "     %1,[%2],#0\n"                   \
 326         "2:\n"                                                  \
 327         "       .pushsection .fixup,\"ax\"\n"                   \
 328         "       .align  2\n"                                    \
 329         "3:     mov     %0, %3\n"                               \
 330         "       b       2b\n"                                   \
 331         "       .popsection\n"                                  \
 332         "       .pushsection __ex_table,\"a\"\n"                \
 333         "       .align  3\n"                                    \
 334         "       .long   1b, 3b\n"                               \
 335         "       .popsection"                                    \
 336         : "+r" (err)                                            \
 337         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 338         : "cc")
 339
 340 #ifndef __ARMEB__
 341 #define __put_user_asm_half(x,__pu_addr,err)                    \
 342 ({                                                              \
 343         unsigned long __temp = (unsigned long)(x);              \
 344         __put_user_asm_byte(__temp, __pu_addr, err);            \
 345         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 346 })
 347 #else
 348 #define __put_user_asm_half(x,__pu_addr,err)                    \
 349 ({                                                              \
 350         unsigned long __temp = (unsigned long)(x);              \
 351         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 352         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 353 })
 354 #endif
 355
 356 #define __put_user_asm_word(x,__pu_addr,err)                    \
 357         __asm__ __volatile__(                                   \
 358         "1:     " T(str) "      %1,[%2],#0\n"                   \
 359         "2:\n"                                                  \
 360         "       .pushsection .fixup,\"ax\"\n"                   \
 361         "       .align  2\n"                                    \
 362         "3:     mov     %0, %3\n"                               \
 363         "       b       2b\n"                                   \
 364         "       .popsection\n"                                  \
 365         "       .pushsection __ex_table,\"a\"\n"                \
 366         "       .align  3\n"                                    \
 367         "       .long   1b, 3b\n"                               \
 368         "       .popsection"                                    \
 369         : "+r" (err)                                            \
 370         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 371         : "cc")
 372
 373 #ifndef __ARMEB__
 374 #define __reg_oper0     "%R2"
 375 #define __reg_oper1     "%Q2"
 376 #else
 377 #define __reg_oper0     "%Q2"
 378 #define __reg_oper1     "%R2"
 379 #endif
 380
 381 #define __put_user_asm_dword(x,__pu_addr,err)                   \
 382         __asm__ __volatile__(                                   \
 383  ARM(   "1:     " T(str) "      " __reg_oper1 ", [%1], #4\n"    )       \
 384  ARM(   "2:     " T(str) "      " __reg_oper0 ", [%1]\n"        )       \
 385  THUMB( "1:     " T(str) "      " __reg_oper1 ", [%1]\n"        )       \
 386  THUMB( "2:     " T(str) "      " __reg_oper0 ", [%1, #4]\n"    )       \
 387         "3:\n"                                                  \
 388         "       .pushsection .fixup,\"ax\"\n"                   \
 389         "       .align  2\n"                                    \
 390         "4:     mov     %0, %3\n"                               \
 391         "       b       3b\n"                                   \
 392         "       .popsection\n"                                  \
 393         "       .pushsection __ex_table,\"a\"\n"                \
 394         "       .align  3\n"                                    \
 395         "       .long   1b, 4b\n"                               \
 396         "       .long   2b, 4b\n"                               \
 397         "       .popsection"                                    \
 398         : "+r" (err), "+r" (__pu_addr)                          \
 399         : "r" (x), "i" (-EFAULT)                                \
 400         : "cc")
 401
 402
 403 #ifdef CONFIG_MMU
 404 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 405 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 406 extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 407 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 408 extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
 409 #else
 410 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
 411 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
 412 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
 413 #endif
 414
 415 extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
 416 extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
 417
 418 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 419 {
 420         if (access_ok(VERIFY_READ, from, n))
 421                 n = __copy_from_user(to, from, n);
 422         else /* security hole - plug it */
 423                 memset(to, 0, n);
 424         return n;
 425 }
 426
 427 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 428 {
 429         if (access_ok(VERIFY_WRITE, to, n))
 430                 n = __copy_to_user(to, from, n);
 431         return n;
 432 }
 433
 434 #define __copy_to_user_inatomic __copy_to_user
 435 #define __copy_from_user_inatomic __copy_from_user
 436
 437 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 438 {
 439         if (access_ok(VERIFY_WRITE, to, n))
 440                 n = __clear_user(to, n);
 441         return n;
 442 }
 443
 444 static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
 445 {
 446         long res = -EFAULT;
 447         if (access_ok(VERIFY_READ, src, 1))
 448                 res = __strncpy_from_user(dst, src, count);
 449         return res;
 450 }
 451
 452 #define strlen_user(s)  strnlen_user(s, ~0UL >> 1)
 453
 454 static inline long __must_check strnlen_user(const char __user *s, long n)
 455 {
 456         unsigned long res = 0;
 457
 458         if (__addr_ok(s))
 459                 res = __strnlen_user(s, n);
 460
 461         return res;
 462 }
 463
 464 #endif /* _ASMARM_UACCESS_H */