include/asm-ppc64/uaccess.h

   1 #ifndef _PPC64_UACCESS_H
   2 #define _PPC64_UACCESS_H
   3
   4 /*
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version
   8  * 2 of the License, or (at your option) any later version.
   9  */
  10
  11 #ifndef __ASSEMBLY__
  12 #include <linux/sched.h>
  13 #include <linux/errno.h>
  14 #include <asm/processor.h>
  15
  16 #define VERIFY_READ     0
  17 #define VERIFY_WRITE    1
  18
  19 /*
  20  * The fs value determines whether argument validity checking should be
  21  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  22  * get_fs() == KERNEL_DS, checking is bypassed.
  23  *
  24  * For historical reasons, these macros are grossly misnamed.
  25  */
  26
  27 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  28
  29 #define KERNEL_DS       MAKE_MM_SEG(0UL)
  30 #define USER_DS         MAKE_MM_SEG(0xf000000000000000UL)
  31
  32 #define get_ds()        (KERNEL_DS)
  33 #define get_fs()        (current->thread.fs)
  34 #define set_fs(val)     (current->thread.fs = (val))
  35
  36 #define segment_eq(a,b) ((a).seg == (b).seg)
  37
  38 /*
  39  * Use the alpha trick for checking ranges:
  40  *
  41  * Is a address valid? This does a straightforward calculation rather
  42  * than tests.
  43  *
  44  * Address valid if:
  45  *  - "addr" doesn't have any high-bits set
  46  *  - AND "size" doesn't have any high-bits set
  47  *  - OR we are in kernel mode.
  48  *
  49  * We dont have to check for high bits in (addr+size) because the first
  50  * two checks force the maximum result to be below the start of the
  51  * kernel region.
  52  */
  53 #define __access_ok(addr,size,segment) \
  54         (((segment).seg & (addr | size )) == 0)
  55
  56 #define access_ok(type,addr,size) \
  57         __access_ok(((__force unsigned long)(addr)),(size),get_fs())
  58
  59 /*
  60  * The exception table consists of pairs of addresses: the first is the
  61  * address of an instruction that is allowed to fault, and the second is
  62  * the address at which the program should continue.  No registers are
  63  * modified, so it is entirely up to the continuation code to figure out
  64  * what to do.
  65  *
  66  * All the routines below use bits of fixup code that are out of line
  67  * with the main instruction path.  This means when everything is well,
  68  * we don't even have to jump over them.  Further, they do not intrude
  69  * on our cache or tlb entries.
  70  */
  71
  72 struct exception_table_entry
  73 {
  74         unsigned long insn, fixup;
  75 };
  76
  77 /* Returns 0 if exception not found and fixup otherwise.  */
  78 extern unsigned long search_exception_table(unsigned long);
  79
  80 /*
  81  * These are the main single-value transfer routines.  They automatically
  82  * use the right size if we just have the right pointer type.
  83  *
  84  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  85  * and yet we don't want to do any pointers, because that is too much
  86  * of a performance impact. Thus we have a few rather ugly macros here,
  87  * and hide all the ugliness from the user.
  88  *
  89  * The "__xxx" versions of the user access functions are versions that
  90  * do not verify the address space, that must have been done previously
  91  * with a separate "access_ok()" call (this is used when we do multiple
  92  * accesses to the same area of user memory).
  93  *
  94  * As we use the same address space for kernel and user data on the
  95  * PowerPC, we can just do these as direct assignments.  (Of course, the
  96  * exception handling means that it's no longer "just"...)
  97  */
  98 #define get_user(x,ptr) \
  99   __get_user_check((x),(ptr),sizeof(*(ptr)))
 100 #define put_user(x,ptr) \
 101   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 102
 103 #define __get_user(x,ptr) \
 104   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 105 #define __put_user(x,ptr) \
 106   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 107
 108 #define __get_user_unaligned __get_user
 109 #define __put_user_unaligned __put_user
 110
 111 extern long __put_user_bad(void);
 112
 113 #define __put_user_nocheck(x,ptr,size)                          \
 114 ({                                                              \
 115         long __pu_err;                                          \
 116         might_sleep();                                          \
 117         __chk_user_ptr(ptr);                                    \
 118         __put_user_size((x),(ptr),(size),__pu_err,-EFAULT);     \
 119         __pu_err;                                               \
 120 })
 121
 122 #define __put_user_check(x,ptr,size)                                    \
 123 ({                                                                      \
 124         long __pu_err = -EFAULT;                                        \
 125         void __user *__pu_addr = (ptr);                                 \
 126         might_sleep();                                                  \
 127         if (access_ok(VERIFY_WRITE,__pu_addr,size))                     \
 128                 __put_user_size((x),__pu_addr,(size),__pu_err,-EFAULT); \
 129         __pu_err;                                                       \
 130 })
 131
 132 #define __put_user_size(x,ptr,size,retval,errret)                       \
 133 do {                                                                    \
 134         retval = 0;                                                     \
 135         switch (size) {                                                 \
 136           case 1: __put_user_asm(x,ptr,retval,"stb",errret); break;     \
 137           case 2: __put_user_asm(x,ptr,retval,"sth",errret); break;     \
 138           case 4: __put_user_asm(x,ptr,retval,"stw",errret); break;     \
 139           case 8: __put_user_asm(x,ptr,retval,"std",errret); break;     \
 140           default: __put_user_bad();                                    \
 141         }                                                               \
 142 } while (0)
 143
 144 /*
 145  * We don't tell gcc that we are accessing memory, but this is OK
 146  * because we do not write to any memory gcc knows about, so there
 147  * are no aliasing issues.
 148  */
 149 #define __put_user_asm(x, addr, err, op, errret)                \
 150         __asm__ __volatile__(                                   \
 151                 "1:     "op" %1,0(%2)   # put_user\n"           \
 152                 "2:\n"                                          \
 153                 ".section .fixup,\"ax\"\n"                      \
 154                 "3:     li %0,%3\n"                             \
 155                 "       b 2b\n"                                 \
 156                 ".previous\n"                                   \
 157                 ".section __ex_table,\"a\"\n"                   \
 158                 "       .align 3\n"                             \
 159                 "       .llong 1b,3b\n"                         \
 160                 ".previous"                                     \
 161                 : "=r"(err)                                     \
 162                 : "r"(x), "b"(addr), "i"(errret), "0"(err))
 163
 164
 165 #define __get_user_nocheck(x,ptr,size)                          \
 166 ({                                                              \
 167         long __gu_err;                                          \
 168         unsigned long __gu_val;                                 \
 169         might_sleep();                                          \
 170         __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
 171         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 172         __gu_err;                                               \
 173 })
 174
 175 #define __get_user_check(x,ptr,size)                                    \
 176 ({                                                                      \
 177         long __gu_err = -EFAULT;                                        \
 178         unsigned long __gu_val = 0;                                     \
 179         const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
 180         might_sleep();                                                  \
 181         if (access_ok(VERIFY_READ,__gu_addr,size))                      \
 182                 __get_user_size(__gu_val,__gu_addr,(size),__gu_err,-EFAULT);\
 183         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 184         __gu_err;                                                       \
 185 })
 186
 187 extern long __get_user_bad(void);
 188
 189 #define __get_user_size(x,ptr,size,retval,errret)                       \
 190 do {                                                                    \
 191         retval = 0;                                                     \
 192         __chk_user_ptr(ptr);                                            \
 193         switch (size) {                                                 \
 194           case 1: __get_user_asm(x,ptr,retval,"lbz",errret); break;     \
 195           case 2: __get_user_asm(x,ptr,retval,"lhz",errret); break;     \
 196           case 4: __get_user_asm(x,ptr,retval,"lwz",errret); break;     \
 197           case 8: __get_user_asm(x,ptr,retval,"ld",errret);  break;     \
 198           default: (x) = __get_user_bad();                              \
 199         }                                                               \
 200 } while (0)
 201
 202 #define __get_user_asm(x, addr, err, op, errret)        \
 203         __asm__ __volatile__(                           \
 204                 "1:     "op" %1,0(%2)   # get_user\n"   \
 205                 "2:\n"                                  \
 206                 ".section .fixup,\"ax\"\n"              \
 207                 "3:     li %0,%3\n"                     \
 208                 "       li %1,0\n"                      \
 209                 "       b 2b\n"                         \
 210                 ".previous\n"                           \
 211                 ".section __ex_table,\"a\"\n"           \
 212                 "       .align 3\n"                     \
 213                 "       .llong 1b,3b\n"                 \
 214                 ".previous"                             \
 215                 : "=r"(err), "=r"(x)                    \
 216                 : "b"(addr), "i"(errret), "0"(err))
 217
 218 /* more complex routines */
 219
 220 extern unsigned long __copy_tofrom_user(void __user *to, const void __user *from,
 221                                         unsigned long size);
 222
 223 static inline unsigned long
 224 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 225 {
 226         if (__builtin_constant_p(n)) {
 227                 unsigned long ret;
 228
 229                 switch (n) {
 230                 case 1:
 231                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 232                         return ret;
 233                 case 2:
 234                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 235                         return ret;
 236                 case 4:
 237                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 238                         return ret;
 239                 case 8:
 240                         __get_user_size(*(u64 *)to, from, 8, ret, 8);
 241                         return ret;
 242                 }
 243         }
 244         return __copy_tofrom_user((__force void __user *) to, from, n);
 245 }
 246
 247 static inline unsigned long
 248 __copy_from_user(void *to, const void __user *from, unsigned long n)
 249 {
 250         might_sleep();
 251         return __copy_from_user_inatomic(to, from, n);
 252 }
 253
 254 static inline unsigned long
 255 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 256 {
 257         if (__builtin_constant_p(n)) {
 258                 unsigned long ret;
 259
 260                 switch (n) {
 261                 case 1:
 262                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
 263                         return ret;
 264                 case 2:
 265                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
 266                         return ret;
 267                 case 4:
 268                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
 269                         return ret;
 270                 case 8:
 271                         __put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret, 8);
 272                         return ret;
 273                 }
 274         }
 275         return __copy_tofrom_user(to, (__force const void __user *) from, n);
 276 }
 277
 278 static inline unsigned long
 279 __copy_to_user(void __user *to, const void *from, unsigned long n)
 280 {
 281         might_sleep();
 282         return __copy_to_user_inatomic(to, from, n);
 283 }
 284
 285 #define __copy_in_user(to, from, size) \
 286         __copy_tofrom_user((to), (from), (size))
 287
 288 extern unsigned long copy_from_user(void *to, const void __user *from,
 289                                     unsigned long n);
 290 extern unsigned long copy_to_user(void __user *to, const void *from,
 291                                   unsigned long n);
 292 extern unsigned long copy_in_user(void __user *to, const void __user *from,
 293                                   unsigned long n);
 294
 295 extern unsigned long __clear_user(void __user *addr, unsigned long size);
 296
 297 static inline unsigned long
 298 clear_user(void __user *addr, unsigned long size)
 299 {
 300         might_sleep();
 301         if (likely(access_ok(VERIFY_WRITE, addr, size)))
 302                 size = __clear_user(addr, size);
 303         return size;
 304 }
 305
 306 extern int __strncpy_from_user(char *dst, const char __user *src, long count);
 307
 308 static inline long
 309 strncpy_from_user(char *dst, const char __user *src, long count)
 310 {
 311         might_sleep();
 312         if (likely(access_ok(VERIFY_READ, src, 1)))
 313                 return __strncpy_from_user(dst, src, count);
 314         return -EFAULT;
 315 }
 316
 317 /*
 318  * Return the size of a string (including the ending 0)
 319  *
 320  * Return 0 for error
 321  */
 322 extern int __strnlen_user(const char __user *str, long len);
 323
 324 /*
 325  * Returns the length of the string at str (including the null byte),
 326  * or 0 if we hit a page we can't access,
 327  * or something > len if we didn't find a null byte.
 328  */
 329 static inline int strnlen_user(const char __user *str, long len)
 330 {
 331         might_sleep();
 332         if (likely(access_ok(VERIFY_READ, str, 1)))
 333                 return __strnlen_user(str, len);
 334         return 0;
 335 }
 336
 337 #define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
 338
 339 #endif  /* __ASSEMBLY__ */
 340
 341 #endif  /* _PPC64_UACCESS_H */