arch/s390/include/asm/uaccess.h

   1 /*
   2  *  include/asm-s390/uaccess.h
   3  *
   4  *  S390 version
   5  *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
   6  *    Author(s): Hartmut Penner (hp@de.ibm.com),
   7  *               Martin Schwidefsky (schwidefsky@de.ibm.com)
   8  *
   9  *  Derived from "include/asm-i386/uaccess.h"
  10  */
  11 #ifndef __S390_UACCESS_H
  12 #define __S390_UACCESS_H
  13
  14 /*
  15  * User space memory access functions
  16  */
  17 #include <linux/sched.h>
  18 #include <linux/errno.h>
  19
  20 #define VERIFY_READ     0
  21 #define VERIFY_WRITE    1
  22
  23
  24 /*
  25  * The fs value determines whether argument validity checking should be
  26  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  27  * get_fs() == KERNEL_DS, checking is bypassed.
  28  *
  29  * For historical reasons, these macros are grossly misnamed.
  30  */
  31
  32 #define MAKE_MM_SEG(a)  ((mm_segment_t) { (a) })
  33
  34
  35 #define KERNEL_DS       MAKE_MM_SEG(0)
  36 #define USER_DS         MAKE_MM_SEG(1)
  37
  38 #define get_ds()        (KERNEL_DS)
  39 #define get_fs()        (current->thread.mm_segment)
  40
  41 #define set_fs(x) \
  42 ({                                                                      \
  43         unsigned long __pto;                                            \
  44         current->thread.mm_segment = (x);                               \
  45         __pto = current->thread.mm_segment.ar4 ?                        \
  46                 S390_lowcore.user_asce : S390_lowcore.kernel_asce;      \
  47         __ctl_load(__pto, 7, 7);                                        \
  48 })
  49
  50 #define segment_eq(a,b) ((a).ar4 == (b).ar4)
  51
  52
  53 static inline int __access_ok(const void __user *addr, unsigned long size)
  54 {
  55         return 1;
  56 }
  57 #define access_ok(type,addr,size) __access_ok(addr,size)
  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 struct uaccess_ops {
  78         size_t (*copy_from_user)(size_t, const void __user *, void *);
  79         size_t (*copy_from_user_small)(size_t, const void __user *, void *);
  80         size_t (*copy_to_user)(size_t, void __user *, const void *);
  81         size_t (*copy_to_user_small)(size_t, void __user *, const void *);
  82         size_t (*copy_in_user)(size_t, void __user *, const void __user *);
  83         size_t (*clear_user)(size_t, void __user *);
  84         size_t (*strnlen_user)(size_t, const char __user *);
  85         size_t (*strncpy_from_user)(size_t, const char __user *, char *);
  86         int (*futex_atomic_op)(int op, int __user *, int oparg, int *old);
  87         int (*futex_atomic_cmpxchg)(int *, int __user *, int old, int new);
  88 };
  89
  90 extern struct uaccess_ops uaccess;
  91 extern struct uaccess_ops uaccess_std;
  92 extern struct uaccess_ops uaccess_mvcos;
  93 extern struct uaccess_ops uaccess_mvcos_switch;
  94 extern struct uaccess_ops uaccess_pt;
  95
  96 extern int __handle_fault(unsigned long, unsigned long, int);
  97
  98 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
  99 {
 100         size = uaccess.copy_to_user_small(size, ptr, x);
 101         return size ? -EFAULT : size;
 102 }
 103
 104 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 105 {
 106         size = uaccess.copy_from_user_small(size, ptr, x);
 107         return size ? -EFAULT : size;
 108 }
 109
 110 /*
 111  * These are the main single-value transfer routines.  They automatically
 112  * use the right size if we just have the right pointer type.
 113  */
 114 #define __put_user(x, ptr) \
 115 ({                                                              \
 116         __typeof__(*(ptr)) __x = (x);                           \
 117         int __pu_err = -EFAULT;                                 \
 118         __chk_user_ptr(ptr);                                    \
 119         switch (sizeof (*(ptr))) {                              \
 120         case 1:                                                 \
 121         case 2:                                                 \
 122         case 4:                                                 \
 123         case 8:                                                 \
 124                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 125                                          ptr, &__x);            \
 126                 break;                                          \
 127         default:                                                \
 128                 __put_user_bad();                               \
 129                 break;                                          \
 130          }                                                      \
 131         __pu_err;                                               \
 132 })
 133
 134 #define put_user(x, ptr)                                        \
 135 ({                                                              \
 136         might_fault();                                          \
 137         __put_user(x, ptr);                                     \
 138 })
 139
 140
 141 extern int __put_user_bad(void) __attribute__((noreturn));
 142
 143 #define __get_user(x, ptr)                                      \
 144 ({                                                              \
 145         int __gu_err = -EFAULT;                                 \
 146         __chk_user_ptr(ptr);                                    \
 147         switch (sizeof(*(ptr))) {                               \
 148         case 1: {                                               \
 149                 unsigned char __x;                              \
 150                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 151                                          ptr, &__x);            \
 152                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 153                 break;                                          \
 154         };                                                      \
 155         case 2: {                                               \
 156                 unsigned short __x;                             \
 157                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 158                                          ptr, &__x);            \
 159                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 160                 break;                                          \
 161         };                                                      \
 162         case 4: {                                               \
 163                 unsigned int __x;                               \
 164                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 165                                          ptr, &__x);            \
 166                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 167                 break;                                          \
 168         };                                                      \
 169         case 8: {                                               \
 170                 unsigned long long __x;                         \
 171                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 172                                          ptr, &__x);            \
 173                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 174                 break;                                          \
 175         };                                                      \
 176         default:                                                \
 177                 __get_user_bad();                               \
 178                 break;                                          \
 179         }                                                       \
 180         __gu_err;                                               \
 181 })
 182
 183 #define get_user(x, ptr)                                        \
 184 ({                                                              \
 185         might_fault();                                          \
 186         __get_user(x, ptr);                                     \
 187 })
 188
 189 extern int __get_user_bad(void) __attribute__((noreturn));
 190
 191 #define __put_user_unaligned __put_user
 192 #define __get_user_unaligned __get_user
 193
 194 /**
 195  * __copy_to_user: - Copy a block of data into user space, with less checking.
 196  * @to:   Destination address, in user space.
 197  * @from: Source address, in kernel space.
 198  * @n:    Number of bytes to copy.
 199  *
 200  * Context: User context only.  This function may sleep.
 201  *
 202  * Copy data from kernel space to user space.  Caller must check
 203  * the specified block with access_ok() before calling this function.
 204  *
 205  * Returns number of bytes that could not be copied.
 206  * On success, this will be zero.
 207  */
 208 static inline unsigned long __must_check
 209 __copy_to_user(void __user *to, const void *from, unsigned long n)
 210 {
 211         if (__builtin_constant_p(n) && (n <= 256))
 212                 return uaccess.copy_to_user_small(n, to, from);
 213         else
 214                 return uaccess.copy_to_user(n, to, from);
 215 }
 216
 217 #define __copy_to_user_inatomic __copy_to_user
 218 #define __copy_from_user_inatomic __copy_from_user
 219
 220 /**
 221  * copy_to_user: - Copy a block of data into user space.
 222  * @to:   Destination address, in user space.
 223  * @from: Source address, in kernel space.
 224  * @n:    Number of bytes to copy.
 225  *
 226  * Context: User context only.  This function may sleep.
 227  *
 228  * Copy data from kernel space to user space.
 229  *
 230  * Returns number of bytes that could not be copied.
 231  * On success, this will be zero.
 232  */
 233 static inline unsigned long __must_check
 234 copy_to_user(void __user *to, const void *from, unsigned long n)
 235 {
 236         might_fault();
 237         if (access_ok(VERIFY_WRITE, to, n))
 238                 n = __copy_to_user(to, from, n);
 239         return n;
 240 }
 241
 242 /**
 243  * __copy_from_user: - Copy a block of data from user space, with less checking.
 244  * @to:   Destination address, in kernel space.
 245  * @from: Source address, in user space.
 246  * @n:    Number of bytes to copy.
 247  *
 248  * Context: User context only.  This function may sleep.
 249  *
 250  * Copy data from user space to kernel space.  Caller must check
 251  * the specified block with access_ok() before calling this function.
 252  *
 253  * Returns number of bytes that could not be copied.
 254  * On success, this will be zero.
 255  *
 256  * If some data could not be copied, this function will pad the copied
 257  * data to the requested size using zero bytes.
 258  */
 259 static inline unsigned long __must_check
 260 __copy_from_user(void *to, const void __user *from, unsigned long n)
 261 {
 262         if (__builtin_constant_p(n) && (n <= 256))
 263                 return uaccess.copy_from_user_small(n, from, to);
 264         else
 265                 return uaccess.copy_from_user(n, from, to);
 266 }
 267
 268 extern void copy_from_user_overflow(void)
 269 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 270 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 271 #endif
 272 ;
 273
 274 /**
 275  * copy_from_user: - Copy a block of data from user space.
 276  * @to:   Destination address, in kernel space.
 277  * @from: Source address, in user space.
 278  * @n:    Number of bytes to copy.
 279  *
 280  * Context: User context only.  This function may sleep.
 281  *
 282  * Copy data from user space to kernel space.
 283  *
 284  * Returns number of bytes that could not be copied.
 285  * On success, this will be zero.
 286  *
 287  * If some data could not be copied, this function will pad the copied
 288  * data to the requested size using zero bytes.
 289  */
 290 static inline unsigned long __must_check
 291 copy_from_user(void *to, const void __user *from, unsigned long n)
 292 {
 293         unsigned int sz = __compiletime_object_size(to);
 294
 295         might_fault();
 296         if (unlikely(sz != -1 && sz < n)) {
 297                 copy_from_user_overflow();
 298                 return n;
 299         }
 300         if (access_ok(VERIFY_READ, from, n))
 301                 n = __copy_from_user(to, from, n);
 302         else
 303                 memset(to, 0, n);
 304         return n;
 305 }
 306
 307 static inline unsigned long __must_check
 308 __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 309 {
 310         return uaccess.copy_in_user(n, to, from);
 311 }
 312
 313 static inline unsigned long __must_check
 314 copy_in_user(void __user *to, const void __user *from, unsigned long n)
 315 {
 316         might_fault();
 317         if (__access_ok(from,n) && __access_ok(to,n))
 318                 n = __copy_in_user(to, from, n);
 319         return n;
 320 }
 321
 322 /*
 323  * Copy a null terminated string from userspace.
 324  */
 325 static inline long __must_check
 326 strncpy_from_user(char *dst, const char __user *src, long count)
 327 {
 328         long res = -EFAULT;
 329         might_fault();
 330         if (access_ok(VERIFY_READ, src, 1))
 331                 res = uaccess.strncpy_from_user(count, src, dst);
 332         return res;
 333 }
 334
 335 static inline unsigned long
 336 strnlen_user(const char __user * src, unsigned long n)
 337 {
 338         might_fault();
 339         return uaccess.strnlen_user(n, src);
 340 }
 341
 342 /**
 343  * strlen_user: - Get the size of a string in user space.
 344  * @str: The string to measure.
 345  *
 346  * Context: User context only.  This function may sleep.
 347  *
 348  * Get the size of a NUL-terminated string in user space.
 349  *
 350  * Returns the size of the string INCLUDING the terminating NUL.
 351  * On exception, returns 0.
 352  *
 353  * If there is a limit on the length of a valid string, you may wish to
 354  * consider using strnlen_user() instead.
 355  */
 356 #define strlen_user(str) strnlen_user(str, ~0UL)
 357
 358 /*
 359  * Zero Userspace
 360  */
 361
 362 static inline unsigned long __must_check
 363 __clear_user(void __user *to, unsigned long n)
 364 {
 365         return uaccess.clear_user(n, to);
 366 }
 367
 368 static inline unsigned long __must_check
 369 clear_user(void __user *to, unsigned long n)
 370 {
 371         might_fault();
 372         if (access_ok(VERIFY_WRITE, to, n))
 373                 n = uaccess.clear_user(n, to);
 374         return n;
 375 }
 376
 377 #endif /* __S390_UACCESS_H */