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 /* this function will go away soon - use access_ok() instead */
  60 static inline int __deprecated verify_area(int type, const void __user *addr, unsigned long size)
  61 {
  62         return access_ok(type,addr,size) ? 0 : -EFAULT;
  63 }
  64
  65
  66 /*
  67  * The exception table consists of pairs of addresses: the first is the
  68  * address of an instruction that is allowed to fault, and the second is
  69  * the address at which the program should continue.  No registers are
  70  * modified, so it is entirely up to the continuation code to figure out
  71  * what to do.
  72  *
  73  * All the routines below use bits of fixup code that are out of line
  74  * with the main instruction path.  This means when everything is well,
  75  * we don't even have to jump over them.  Further, they do not intrude
  76  * on our cache or tlb entries.
  77  */
  78
  79 struct exception_table_entry
  80 {
  81         unsigned long insn, fixup;
  82 };
  83
  84 /* Returns 0 if exception not found and fixup otherwise.  */
  85 extern unsigned long search_exception_table(unsigned long);
  86
  87 /*
  88  * These are the main single-value transfer routines.  They automatically
  89  * use the right size if we just have the right pointer type.
  90  *
  91  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  92  * and yet we don't want to do any pointers, because that is too much
  93  * of a performance impact. Thus we have a few rather ugly macros here,
  94  * and hide all the ugliness from the user.
  95  *
  96  * The "__xxx" versions of the user access functions are versions that
  97  * do not verify the address space, that must have been done previously
  98  * with a separate "access_ok()" call (this is used when we do multiple
  99  * accesses to the same area of user memory).
 100  *
 101  * As we use the same address space for kernel and user data on the
 102  * PowerPC, we can just do these as direct assignments.  (Of course, the
 103  * exception handling means that it's no longer "just"...)
 104  */
 105 #define get_user(x,ptr) \
 106   __get_user_check((x),(ptr),sizeof(*(ptr)))
 107 #define put_user(x,ptr) \
 108   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 109
 110 #define __get_user(x,ptr) \
 111   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 112 #define __put_user(x,ptr) \
 113   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 114
 115 #define __get_user_unaligned __get_user
 116 #define __put_user_unaligned __put_user
 117
 118 extern long __put_user_bad(void);
 119
 120 #define __put_user_nocheck(x,ptr,size)                          \
 121 ({                                                              \
 122         long __pu_err;                                          \
 123         might_sleep();                                          \
 124         __chk_user_ptr(ptr);                                    \
 125         __put_user_size((x),(ptr),(size),__pu_err,-EFAULT);     \
 126         __pu_err;                                               \
 127 })
 128
 129 #define __put_user_check(x,ptr,size)                                    \
 130 ({                                                                      \
 131         long __pu_err = -EFAULT;                                        \
 132         void __user *__pu_addr = (ptr);                                 \
 133         might_sleep();                                                  \
 134         if (access_ok(VERIFY_WRITE,__pu_addr,size))                     \
 135                 __put_user_size((x),__pu_addr,(size),__pu_err,-EFAULT); \
 136         __pu_err;                                                       \
 137 })
 138
 139 #define __put_user_size(x,ptr,size,retval,errret)                       \
 140 do {                                                                    \
 141         retval = 0;                                                     \
 142         switch (size) {                                                 \
 143           case 1: __put_user_asm(x,ptr,retval,"stb",errret); break;     \
 144           case 2: __put_user_asm(x,ptr,retval,"sth",errret); break;     \
 145           case 4: __put_user_asm(x,ptr,retval,"stw",errret); break;     \
 146           case 8: __put_user_asm(x,ptr,retval,"std",errret); break;     \
 147           default: __put_user_bad();                                    \
 148         }                                                               \
 149 } while (0)
 150
 151 /*
 152  * We don't tell gcc that we are accessing memory, but this is OK
 153  * because we do not write to any memory gcc knows about, so there
 154  * are no aliasing issues.
 155  */
 156 #define __put_user_asm(x, addr, err, op, errret)                \
 157         __asm__ __volatile__(                                   \
 158                 "1:     "op" %1,0(%2)   # put_user\n"           \
 159                 "2:\n"                                          \
 160                 ".section .fixup,\"ax\"\n"                      \
 161                 "3:     li %0,%3\n"                             \
 162                 "       b 2b\n"                                 \
 163                 ".previous\n"                                   \
 164                 ".section __ex_table,\"a\"\n"                   \
 165                 "       .align 3\n"                             \
 166                 "       .llong 1b,3b\n"                         \
 167                 ".previous"                                     \
 168                 : "=r"(err)                                     \
 169                 : "r"(x), "b"(addr), "i"(errret), "0"(err))
 170
 171
 172 #define __get_user_nocheck(x,ptr,size)                          \
 173 ({                                                              \
 174         long __gu_err, __gu_val;                                \
 175         might_sleep();                                          \
 176         __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
 177         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 178         __gu_err;                                               \
 179 })
 180
 181 #define __get_user_check(x,ptr,size)                                    \
 182 ({                                                                      \
 183         long __gu_err = -EFAULT, __gu_val = 0;                          \
 184         const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
 185         might_sleep();                                                  \
 186         if (access_ok(VERIFY_READ,__gu_addr,size))                      \
 187                 __get_user_size(__gu_val,__gu_addr,(size),__gu_err,-EFAULT);\
 188         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 189         __gu_err;                                                       \
 190 })
 191
 192 extern long __get_user_bad(void);
 193
 194 #define __get_user_size(x,ptr,size,retval,errret)                       \
 195 do {                                                                    \
 196         retval = 0;                                                     \
 197         __chk_user_ptr(ptr);                                            \
 198         switch (size) {                                                 \
 199           case 1: __get_user_asm(x,ptr,retval,"lbz",errret); break;     \
 200           case 2: __get_user_asm(x,ptr,retval,"lhz",errret); break;     \
 201           case 4: __get_user_asm(x,ptr,retval,"lwz",errret); break;     \
 202           case 8: __get_user_asm(x,ptr,retval,"ld",errret);  break;     \
 203           default: (x) = __get_user_bad();                              \
 204         }                                                               \
 205 } while (0)
 206
 207 #define __get_user_asm(x, addr, err, op, errret)        \
 208         __asm__ __volatile__(                           \
 209                 "1:     "op" %1,0(%2)   # get_user\n"   \
 210                 "2:\n"                                  \
 211                 ".section .fixup,\"ax\"\n"              \
 212                 "3:     li %0,%3\n"                     \
 213                 "       li %1,0\n"                      \
 214                 "       b 2b\n"                         \
 215                 ".previous\n"                           \
 216                 ".section __ex_table,\"a\"\n"           \
 217                 "       .align 3\n"                     \
 218                 "       .llong 1b,3b\n"                 \
 219                 ".previous"                             \
 220                 : "=r"(err), "=r"(x)                    \
 221                 : "b"(addr), "i"(errret), "0"(err))
 222
 223 /* more complex routines */
 224
 225 extern unsigned long __copy_tofrom_user(void __user *to, const void __user *from,
 226                                         unsigned long size);
 227
 228 static inline unsigned long
 229 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 230 {
 231         if (__builtin_constant_p(n)) {
 232                 unsigned long ret;
 233
 234                 switch (n) {
 235                 case 1:
 236                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 237                         return ret;
 238                 case 2:
 239                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 240                         return ret;
 241                 case 4:
 242                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 243                         return ret;
 244                 case 8:
 245                         __get_user_size(*(u64 *)to, from, 8, ret, 8);
 246                         return ret;
 247                 }
 248         }
 249         return __copy_tofrom_user((__force void __user *) to, from, n);
 250 }
 251
 252 static inline unsigned long
 253 __copy_from_user(void *to, const void __user *from, unsigned long n)
 254 {
 255         might_sleep();
 256         return __copy_from_user_inatomic(to, from, n);
 257 }
 258
 259 static inline unsigned long
 260 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 261 {
 262         if (__builtin_constant_p(n)) {
 263                 unsigned long ret;
 264
 265                 switch (n) {
 266                 case 1:
 267                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
 268                         return ret;
 269                 case 2:
 270                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
 271                         return ret;
 272                 case 4:
 273                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
 274                         return ret;
 275                 case 8:
 276                         __put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret, 8);
 277                         return ret;
 278                 }
 279         }
 280         return __copy_tofrom_user(to, (__force const void __user *) from, n);
 281 }
 282
 283 static inline unsigned long
 284 __copy_to_user(void __user *to, const void *from, unsigned long n)
 285 {
 286         might_sleep();
 287         return __copy_to_user_inatomic(to, from, n);
 288 }
 289
 290 #define __copy_in_user(to, from, size) \
 291         __copy_tofrom_user((to), (from), (size))
 292
 293 extern unsigned long copy_from_user(void *to, const void __user *from,
 294                                     unsigned long n);
 295 extern unsigned long copy_to_user(void __user *to, const void *from,
 296                                   unsigned long n);
 297 extern unsigned long copy_in_user(void __user *to, const void __user *from,
 298                                   unsigned long n);
 299
 300 extern unsigned long __clear_user(void __user *addr, unsigned long size);
 301
 302 static inline unsigned long
 303 clear_user(void __user *addr, unsigned long size)
 304 {
 305         might_sleep();
 306         if (likely(access_ok(VERIFY_WRITE, addr, size)))
 307                 size = __clear_user(addr, size);
 308         return size;
 309 }
 310
 311 extern int __strncpy_from_user(char *dst, const char __user *src, long count);
 312
 313 static inline long
 314 strncpy_from_user(char *dst, const char __user *src, long count)
 315 {
 316         might_sleep();
 317         if (likely(access_ok(VERIFY_READ, src, 1)))
 318                 return __strncpy_from_user(dst, src, count);
 319         return -EFAULT;
 320 }
 321
 322 /*
 323  * Return the size of a string (including the ending 0)
 324  *
 325  * Return 0 for error
 326  */
 327 extern int __strnlen_user(const char __user *str, long len);
 328
 329 /*
 330  * Returns the length of the string at str (including the null byte),
 331  * or 0 if we hit a page we can't access,
 332  * or something > len if we didn't find a null byte.
 333  */
 334 static inline int strnlen_user(const char __user *str, long len)
 335 {
 336         might_sleep();
 337         if (likely(access_ok(VERIFY_READ, str, 1)))
 338                 return __strnlen_user(str, len);
 339         return 0;
 340 }
 341
 342 #define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
 343
 344 #endif  /* __ASSEMBLY__ */
 345
 346 #endif  /* _PPC64_UACCESS_H */