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 __get_user_x(__r2,__p,__e,__s,__i...)                           \
 105            __asm__ __volatile__ (                                       \
 106                 __asmeq("%0", "r0") __asmeq("%1", "r2")                 \
 107                 "bl     __get_user_" #__s                               \
 108                 : "=&r" (__e), "=r" (__r2)                              \
 109                 : "0" (__p)                                             \
 110                 : __i, "cc")
 111
 112 #define get_user(x,p)                                                   \
 113         ({                                                              \
 114                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 115                 register unsigned long __r2 asm("r2");                  \
 116                 register int __e asm("r0");                             \
 117                 switch (sizeof(*(__p))) {                               \
 118                 case 1:                                                 \
 119                         __get_user_x(__r2, __p, __e, 1, "lr");          \
 120                         break;                                          \
 121                 case 2:                                                 \
 122                         __get_user_x(__r2, __p, __e, 2, "r3", "lr");    \
 123                         break;                                          \
 124                 case 4:                                                 \
 125                         __get_user_x(__r2, __p, __e, 4, "lr");          \
 126                         break;                                          \
 127                 default: __e = __get_user_bad(); break;                 \
 128                 }                                                       \
 129                 x = (typeof(*(p))) __r2;                                \
 130                 __e;                                                    \
 131         })
 132
 133 extern int __put_user_1(void *, unsigned int);
 134 extern int __put_user_2(void *, unsigned int);
 135 extern int __put_user_4(void *, unsigned int);
 136 extern int __put_user_8(void *, unsigned long long);
 137
 138 #define __put_user_x(__r2,__p,__e,__s)                                  \
 139            __asm__ __volatile__ (                                       \
 140                 __asmeq("%0", "r0") __asmeq("%2", "r2")                 \
 141                 "bl     __put_user_" #__s                               \
 142                 : "=&r" (__e)                                           \
 143                 : "0" (__p), "r" (__r2)                                 \
 144                 : "ip", "lr", "cc")
 145
 146 #define put_user(x,p)                                                   \
 147         ({                                                              \
 148                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
 149                 register const typeof(*(p)) __user *__p asm("r0") = (p);\
 150                 register int __e asm("r0");                             \
 151                 switch (sizeof(*(__p))) {                               \
 152                 case 1:                                                 \
 153                         __put_user_x(__r2, __p, __e, 1);                \
 154                         break;                                          \
 155                 case 2:                                                 \
 156                         __put_user_x(__r2, __p, __e, 2);                \
 157                         break;                                          \
 158                 case 4:                                                 \
 159                         __put_user_x(__r2, __p, __e, 4);                \
 160                         break;                                          \
 161                 case 8:                                                 \
 162                         __put_user_x(__r2, __p, __e, 8);                \
 163                         break;                                          \
 164                 default: __e = __put_user_bad(); break;                 \
 165                 }                                                       \
 166                 __e;                                                    \
 167         })
 168
 169 #else /* CONFIG_MMU */
 170
 171 /*
 172  * uClinux has only one addr space, so has simplified address limits.
 173  */
 174 #define USER_DS                 KERNEL_DS
 175
 176 #define segment_eq(a,b)         (1)
 177 #define __addr_ok(addr)         (1)
 178 #define __range_ok(addr,size)   (0)
 179 #define get_fs()                (KERNEL_DS)
 180
 181 static inline void set_fs(mm_segment_t fs)
 182 {
 183 }
 184
 185 #define get_user(x,p)   __get_user(x,p)
 186 #define put_user(x,p)   __put_user(x,p)
 187
 188 #endif /* CONFIG_MMU */
 189
 190 #define access_ok(type,addr,size)       (__range_ok(addr,size) == 0)
 191
 192 /*
 193  * The "__xxx" versions of the user access functions do not verify the
 194  * address space - it must have been done previously with a separate
 195  * "access_ok()" call.
 196  *
 197  * The "xxx_error" versions set the third argument to EFAULT if an
 198  * error occurs, and leave it unchanged on success.  Note that these
 199  * versions are void (ie, don't return a value as such).
 200  */
 201 #define __get_user(x,ptr)                                               \
 202 ({                                                                      \
 203         long __gu_err = 0;                                              \
 204         __get_user_err((x),(ptr),__gu_err);                             \
 205         __gu_err;                                                       \
 206 })
 207
 208 #define __get_user_error(x,ptr,err)                                     \
 209 ({                                                                      \
 210         __get_user_err((x),(ptr),err);                                  \
 211         (void) 0;                                                       \
 212 })
 213
 214 #define __get_user_err(x,ptr,err)                                       \
 215 do {                                                                    \
 216         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 217         unsigned long __gu_val;                                         \
 218         __chk_user_ptr(ptr);                                            \
 219         switch (sizeof(*(ptr))) {                                       \
 220         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
 221         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
 222         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
 223         default: (__gu_val) = __get_user_bad();                         \
 224         }                                                               \
 225         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 226 } while (0)
 227
 228 #define __get_user_asm_byte(x,addr,err)                         \
 229         __asm__ __volatile__(                                   \
 230         "1:     ldrbt   %1,[%2]\n"                              \
 231         "2:\n"                                                  \
 232         "       .pushsection .fixup,\"ax\"\n"                   \
 233         "       .align  2\n"                                    \
 234         "3:     mov     %0, %3\n"                               \
 235         "       mov     %1, #0\n"                               \
 236         "       b       2b\n"                                   \
 237         "       .popsection\n"                                  \
 238         "       .pushsection __ex_table,\"a\"\n"                \
 239         "       .align  3\n"                                    \
 240         "       .long   1b, 3b\n"                               \
 241         "       .popsection"                                    \
 242         : "+r" (err), "=&r" (x)                                 \
 243         : "r" (addr), "i" (-EFAULT)                             \
 244         : "cc")
 245
 246 #ifndef __ARMEB__
 247 #define __get_user_asm_half(x,__gu_addr,err)                    \
 248 ({                                                              \
 249         unsigned long __b1, __b2;                               \
 250         __get_user_asm_byte(__b1, __gu_addr, err);              \
 251         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 252         (x) = __b1 | (__b2 << 8);                               \
 253 })
 254 #else
 255 #define __get_user_asm_half(x,__gu_addr,err)                    \
 256 ({                                                              \
 257         unsigned long __b1, __b2;                               \
 258         __get_user_asm_byte(__b1, __gu_addr, err);              \
 259         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 260         (x) = (__b1 << 8) | __b2;                               \
 261 })
 262 #endif
 263
 264 #define __get_user_asm_word(x,addr,err)                         \
 265         __asm__ __volatile__(                                   \
 266         "1:     ldrt    %1,[%2]\n"                              \
 267         "2:\n"                                                  \
 268         "       .pushsection .fixup,\"ax\"\n"                   \
 269         "       .align  2\n"                                    \
 270         "3:     mov     %0, %3\n"                               \
 271         "       mov     %1, #0\n"                               \
 272         "       b       2b\n"                                   \
 273         "       .popsection\n"                                  \
 274         "       .pushsection __ex_table,\"a\"\n"                \
 275         "       .align  3\n"                                    \
 276         "       .long   1b, 3b\n"                               \
 277         "       .popsection"                                    \
 278         : "+r" (err), "=&r" (x)                                 \
 279         : "r" (addr), "i" (-EFAULT)                             \
 280         : "cc")
 281
 282 #define __put_user(x,ptr)                                               \
 283 ({                                                                      \
 284         long __pu_err = 0;                                              \
 285         __put_user_err((x),(ptr),__pu_err);                             \
 286         __pu_err;                                                       \
 287 })
 288
 289 #define __put_user_error(x,ptr,err)                                     \
 290 ({                                                                      \
 291         __put_user_err((x),(ptr),err);                                  \
 292         (void) 0;                                                       \
 293 })
 294
 295 #define __put_user_err(x,ptr,err)                                       \
 296 do {                                                                    \
 297         unsigned long __pu_addr = (unsigned long)(ptr);                 \
 298         __typeof__(*(ptr)) __pu_val = (x);                              \
 299         __chk_user_ptr(ptr);                                            \
 300         switch (sizeof(*(ptr))) {                                       \
 301         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
 302         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
 303         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
 304         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
 305         default: __put_user_bad();                                      \
 306         }                                                               \
 307 } while (0)
 308
 309 #define __put_user_asm_byte(x,__pu_addr,err)                    \
 310         __asm__ __volatile__(                                   \
 311         "1:     strbt   %1,[%2]\n"                              \
 312         "2:\n"                                                  \
 313         "       .pushsection .fixup,\"ax\"\n"                   \
 314         "       .align  2\n"                                    \
 315         "3:     mov     %0, %3\n"                               \
 316         "       b       2b\n"                                   \
 317         "       .popsection\n"                                  \
 318         "       .pushsection __ex_table,\"a\"\n"                \
 319         "       .align  3\n"                                    \
 320         "       .long   1b, 3b\n"                               \
 321         "       .popsection"                                    \
 322         : "+r" (err)                                            \
 323         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 324         : "cc")
 325
 326 #ifndef __ARMEB__
 327 #define __put_user_asm_half(x,__pu_addr,err)                    \
 328 ({                                                              \
 329         unsigned long __temp = (unsigned long)(x);              \
 330         __put_user_asm_byte(__temp, __pu_addr, err);            \
 331         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 332 })
 333 #else
 334 #define __put_user_asm_half(x,__pu_addr,err)                    \
 335 ({                                                              \
 336         unsigned long __temp = (unsigned long)(x);              \
 337         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 338         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 339 })
 340 #endif
 341
 342 #define __put_user_asm_word(x,__pu_addr,err)                    \
 343         __asm__ __volatile__(                                   \
 344         "1:     strt    %1,[%2]\n"                              \
 345         "2:\n"                                                  \
 346         "       .pushsection .fixup,\"ax\"\n"                   \
 347         "       .align  2\n"                                    \
 348         "3:     mov     %0, %3\n"                               \
 349         "       b       2b\n"                                   \
 350         "       .popsection\n"                                  \
 351         "       .pushsection __ex_table,\"a\"\n"                \
 352         "       .align  3\n"                                    \
 353         "       .long   1b, 3b\n"                               \
 354         "       .popsection"                                    \
 355         : "+r" (err)                                            \
 356         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 357         : "cc")
 358
 359 #ifndef __ARMEB__
 360 #define __reg_oper0     "%R2"
 361 #define __reg_oper1     "%Q2"
 362 #else
 363 #define __reg_oper0     "%Q2"
 364 #define __reg_oper1     "%R2"
 365 #endif
 366
 367 #define __put_user_asm_dword(x,__pu_addr,err)                   \
 368         __asm__ __volatile__(                                   \
 369  ARM(   "1:     strt    " __reg_oper1 ", [%1], #4\n"    )       \
 370  ARM(   "2:     strt    " __reg_oper0 ", [%1]\n"        )       \
 371  THUMB( "1:     strt    " __reg_oper1 ", [%1]\n"        )       \
 372  THUMB( "2:     strt    " __reg_oper0 ", [%1, #4]\n"    )       \
 373         "3:\n"                                                  \
 374         "       .pushsection .fixup,\"ax\"\n"                   \
 375         "       .align  2\n"                                    \
 376         "4:     mov     %0, %3\n"                               \
 377         "       b       3b\n"                                   \
 378         "       .popsection\n"                                  \
 379         "       .pushsection __ex_table,\"a\"\n"                \
 380         "       .align  3\n"                                    \
 381         "       .long   1b, 4b\n"                               \
 382         "       .long   2b, 4b\n"                               \
 383         "       .popsection"                                    \
 384         : "+r" (err), "+r" (__pu_addr)                          \
 385         : "r" (x), "i" (-EFAULT)                                \
 386         : "cc")
 387
 388
 389 #ifdef CONFIG_MMU
 390 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 391 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 392 extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 393 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 394 extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
 395 #else
 396 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
 397 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
 398 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
 399 #endif
 400
 401 extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
 402 extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
 403
 404 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 405 {
 406         if (access_ok(VERIFY_READ, from, n))
 407                 n = __copy_from_user(to, from, n);
 408         else /* security hole - plug it */
 409                 memset(to, 0, n);
 410         return n;
 411 }
 412
 413 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
 414 {
 415         if (access_ok(VERIFY_WRITE, to, n))
 416                 n = __copy_to_user(to, from, n);
 417         return n;
 418 }
 419
 420 #define __copy_to_user_inatomic __copy_to_user
 421 #define __copy_from_user_inatomic __copy_from_user
 422
 423 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
 424 {
 425         if (access_ok(VERIFY_WRITE, to, n))
 426                 n = __clear_user(to, n);
 427         return n;
 428 }
 429
 430 static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
 431 {
 432         long res = -EFAULT;
 433         if (access_ok(VERIFY_READ, src, 1))
 434                 res = __strncpy_from_user(dst, src, count);
 435         return res;
 436 }
 437
 438 #define strlen_user(s)  strnlen_user(s, ~0UL >> 1)
 439
 440 static inline long __must_check strnlen_user(const char __user *s, long n)
 441 {
 442         unsigned long res = 0;
 443
 444         if (__addr_ok(s))
 445                 res = __strnlen_user(s, n);
 446
 447         return res;
 448 }
 449
 450 #endif /* _ASMARM_UACCESS_H */