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 __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 #define user_addr_max() \
 193         (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
 194
 195 /*
 196  * The "__xxx" versions of the user access functions do not verify the
 197  * address space - it must have been done previously with a separate
 198  * "access_ok()" call.
 199  *
 200  * The "xxx_error" versions set the third argument to EFAULT if an
 201  * error occurs, and leave it unchanged on success.  Note that these
 202  * versions are void (ie, don't return a value as such).
 203  */
 204 #define __get_user(x,ptr)                                               \
 205 ({                                                                      \
 206         long __gu_err = 0;                                              \
 207         __get_user_err((x),(ptr),__gu_err);                             \
 208         __gu_err;                                                       \
 209 })
 210
 211 #define __get_user_error(x,ptr,err)                                     \
 212 ({                                                                      \
 213         __get_user_err((x),(ptr),err);                                  \
 214         (void) 0;                                                       \
 215 })
 216
 217 #define __get_user_err(x,ptr,err)                                       \
 218 do {                                                                    \
 219         unsigned long __gu_addr = (unsigned long)(ptr);                 \
 220         unsigned long __gu_val;                                         \
 221         __chk_user_ptr(ptr);                                            \
 222         switch (sizeof(*(ptr))) {                                       \
 223         case 1: __get_user_asm_byte(__gu_val,__gu_addr,err);    break;  \
 224         case 2: __get_user_asm_half(__gu_val,__gu_addr,err);    break;  \
 225         case 4: __get_user_asm_word(__gu_val,__gu_addr,err);    break;  \
 226         default: (__gu_val) = __get_user_bad();                         \
 227         }                                                               \
 228         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 229 } while (0)
 230
 231 #define __get_user_asm_byte(x,addr,err)                         \
 232         __asm__ __volatile__(                                   \
 233         "1:     " TUSER(ldrb) " %1,[%2],#0\n"                   \
 234         "2:\n"                                                  \
 235         "       .pushsection .fixup,\"ax\"\n"                   \
 236         "       .align  2\n"                                    \
 237         "3:     mov     %0, %3\n"                               \
 238         "       mov     %1, #0\n"                               \
 239         "       b       2b\n"                                   \
 240         "       .popsection\n"                                  \
 241         "       .pushsection __ex_table,\"a\"\n"                \
 242         "       .align  3\n"                                    \
 243         "       .long   1b, 3b\n"                               \
 244         "       .popsection"                                    \
 245         : "+r" (err), "=&r" (x)                                 \
 246         : "r" (addr), "i" (-EFAULT)                             \
 247         : "cc")
 248
 249 #ifndef __ARMEB__
 250 #define __get_user_asm_half(x,__gu_addr,err)                    \
 251 ({                                                              \
 252         unsigned long __b1, __b2;                               \
 253         __get_user_asm_byte(__b1, __gu_addr, err);              \
 254         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 255         (x) = __b1 | (__b2 << 8);                               \
 256 })
 257 #else
 258 #define __get_user_asm_half(x,__gu_addr,err)                    \
 259 ({                                                              \
 260         unsigned long __b1, __b2;                               \
 261         __get_user_asm_byte(__b1, __gu_addr, err);              \
 262         __get_user_asm_byte(__b2, __gu_addr + 1, err);          \
 263         (x) = (__b1 << 8) | __b2;                               \
 264 })
 265 #endif
 266
 267 #define __get_user_asm_word(x,addr,err)                         \
 268         __asm__ __volatile__(                                   \
 269         "1:     " TUSER(ldr) "  %1,[%2],#0\n"                   \
 270         "2:\n"                                                  \
 271         "       .pushsection .fixup,\"ax\"\n"                   \
 272         "       .align  2\n"                                    \
 273         "3:     mov     %0, %3\n"                               \
 274         "       mov     %1, #0\n"                               \
 275         "       b       2b\n"                                   \
 276         "       .popsection\n"                                  \
 277         "       .pushsection __ex_table,\"a\"\n"                \
 278         "       .align  3\n"                                    \
 279         "       .long   1b, 3b\n"                               \
 280         "       .popsection"                                    \
 281         : "+r" (err), "=&r" (x)                                 \
 282         : "r" (addr), "i" (-EFAULT)                             \
 283         : "cc")
 284
 285 #define __put_user(x,ptr)                                               \
 286 ({                                                                      \
 287         long __pu_err = 0;                                              \
 288         __put_user_err((x),(ptr),__pu_err);                             \
 289         __pu_err;                                                       \
 290 })
 291
 292 #define __put_user_error(x,ptr,err)                                     \
 293 ({                                                                      \
 294         __put_user_err((x),(ptr),err);                                  \
 295         (void) 0;                                                       \
 296 })
 297
 298 #define __put_user_err(x,ptr,err)                                       \
 299 do {                                                                    \
 300         unsigned long __pu_addr = (unsigned long)(ptr);                 \
 301         __typeof__(*(ptr)) __pu_val = (x);                              \
 302         __chk_user_ptr(ptr);                                            \
 303         switch (sizeof(*(ptr))) {                                       \
 304         case 1: __put_user_asm_byte(__pu_val,__pu_addr,err);    break;  \
 305         case 2: __put_user_asm_half(__pu_val,__pu_addr,err);    break;  \
 306         case 4: __put_user_asm_word(__pu_val,__pu_addr,err);    break;  \
 307         case 8: __put_user_asm_dword(__pu_val,__pu_addr,err);   break;  \
 308         default: __put_user_bad();                                      \
 309         }                                                               \
 310 } while (0)
 311
 312 #define __put_user_asm_byte(x,__pu_addr,err)                    \
 313         __asm__ __volatile__(                                   \
 314         "1:     " TUSER(strb) " %1,[%2],#0\n"                   \
 315         "2:\n"                                                  \
 316         "       .pushsection .fixup,\"ax\"\n"                   \
 317         "       .align  2\n"                                    \
 318         "3:     mov     %0, %3\n"                               \
 319         "       b       2b\n"                                   \
 320         "       .popsection\n"                                  \
 321         "       .pushsection __ex_table,\"a\"\n"                \
 322         "       .align  3\n"                                    \
 323         "       .long   1b, 3b\n"                               \
 324         "       .popsection"                                    \
 325         : "+r" (err)                                            \
 326         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 327         : "cc")
 328
 329 #ifndef __ARMEB__
 330 #define __put_user_asm_half(x,__pu_addr,err)                    \
 331 ({                                                              \
 332         unsigned long __temp = (unsigned long)(x);              \
 333         __put_user_asm_byte(__temp, __pu_addr, err);            \
 334         __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err);   \
 335 })
 336 #else
 337 #define __put_user_asm_half(x,__pu_addr,err)                    \
 338 ({                                                              \
 339         unsigned long __temp = (unsigned long)(x);              \
 340         __put_user_asm_byte(__temp >> 8, __pu_addr, err);       \
 341         __put_user_asm_byte(__temp, __pu_addr + 1, err);        \
 342 })
 343 #endif
 344
 345 #define __put_user_asm_word(x,__pu_addr,err)                    \
 346         __asm__ __volatile__(                                   \
 347         "1:     " TUSER(str) "  %1,[%2],#0\n"                   \
 348         "2:\n"                                                  \
 349         "       .pushsection .fixup,\"ax\"\n"                   \
 350         "       .align  2\n"                                    \
 351         "3:     mov     %0, %3\n"                               \
 352         "       b       2b\n"                                   \
 353         "       .popsection\n"                                  \
 354         "       .pushsection __ex_table,\"a\"\n"                \
 355         "       .align  3\n"                                    \
 356         "       .long   1b, 3b\n"                               \
 357         "       .popsection"                                    \
 358         : "+r" (err)                                            \
 359         : "r" (x), "r" (__pu_addr), "i" (-EFAULT)               \
 360         : "cc")
 361
 362 #ifndef __ARMEB__
 363 #define __reg_oper0     "%R2"
 364 #define __reg_oper1     "%Q2"
 365 #else
 366 #define __reg_oper0     "%Q2"
 367 #define __reg_oper1     "%R2"
 368 #endif
 369
 370 #define __put_user_asm_dword(x,__pu_addr,err)                   \
 371         __asm__ __volatile__(                                   \
 372  ARM(   "1:     " TUSER(str) "  " __reg_oper1 ", [%1], #4\n"    ) \
 373  ARM(   "2:     " TUSER(str) "  " __reg_oper0 ", [%1]\n"        ) \
 374  THUMB( "1:     " TUSER(str) "  " __reg_oper1 ", [%1]\n"        ) \
 375  THUMB( "2:     " TUSER(str) "  " __reg_oper0 ", [%1, #4]\n"    ) \
 376         "3:\n"                                                  \
 377         "       .pushsection .fixup,\"ax\"\n"                   \
 378         "       .align  2\n"                                    \
 379         "4:     mov     %0, %3\n"                               \
 380         "       b       3b\n"                                   \
 381         "       .popsection\n"                                  \
 382         "       .pushsection __ex_table,\"a\"\n"                \
 383         "       .align  3\n"                                    \
 384         "       .long   1b, 4b\n"                               \
 385         "       .long   2b, 4b\n"                               \
 386         "       .popsection"                                    \
 387         : "+r" (err), "+r" (__pu_addr)                          \
 388         : "r" (x), "i" (-EFAULT)                                \
 389         : "cc")
 390
 391
 392 #ifdef CONFIG_MMU
 393 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
 394 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
 395 extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
 396 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
 397 extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
 398 #else
 399 #define __copy_from_user(to,from,n)     (memcpy(to, (void __force *)from, n), 0)
 400 #define __copy_to_user(to,from,n)       (memcpy((void __force *)to, from, n), 0)
 401 #define __clear_user(addr,n)            (memset((void __force *)addr, 0, n), 0)
 402 #endif
 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 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 431
 432 extern __must_check long strlen_user(const char __user *str);
 433 extern __must_check long strnlen_user(const char __user *str, long n);
 434
 435 #endif /* _ASMARM_UACCESS_H */