include/asm-s390/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 __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
  94 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
  95 {
  96         size = uaccess.copy_to_user_small(size, ptr, x);
  97         return size ? -EFAULT : size;
  98 }
  99
 100 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 101 {
 102         size = uaccess.copy_from_user_small(size, ptr, x);
 103         return size ? -EFAULT : size;
 104 }
 105
 106 /*
 107  * These are the main single-value transfer routines.  They automatically
 108  * use the right size if we just have the right pointer type.
 109  */
 110 #define __put_user(x, ptr) \
 111 ({                                                              \
 112         __typeof__(*(ptr)) __x = (x);                           \
 113         int __pu_err = -EFAULT;                                 \
 114         __chk_user_ptr(ptr);                                    \
 115         switch (sizeof (*(ptr))) {                              \
 116         case 1:                                                 \
 117         case 2:                                                 \
 118         case 4:                                                 \
 119         case 8:                                                 \
 120                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 121                                          ptr, &__x);            \
 122                 break;                                          \
 123         default:                                                \
 124                 __put_user_bad();                               \
 125                 break;                                          \
 126          }                                                      \
 127         __pu_err;                                               \
 128 })
 129
 130 #define put_user(x, ptr)                                        \
 131 ({                                                              \
 132         might_sleep();                                          \
 133         __put_user(x, ptr);                                     \
 134 })
 135
 136
 137 extern int __put_user_bad(void) __attribute__((noreturn));
 138
 139 #define __get_user(x, ptr)                                      \
 140 ({                                                              \
 141         int __gu_err = -EFAULT;                                 \
 142         __chk_user_ptr(ptr);                                    \
 143         switch (sizeof(*(ptr))) {                               \
 144         case 1: {                                               \
 145                 unsigned char __x;                              \
 146                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 147                                          ptr, &__x);            \
 148                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 149                 break;                                          \
 150         };                                                      \
 151         case 2: {                                               \
 152                 unsigned short __x;                             \
 153                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 154                                          ptr, &__x);            \
 155                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 156                 break;                                          \
 157         };                                                      \
 158         case 4: {                                               \
 159                 unsigned int __x;                               \
 160                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 161                                          ptr, &__x);            \
 162                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 163                 break;                                          \
 164         };                                                      \
 165         case 8: {                                               \
 166                 unsigned long long __x;                         \
 167                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 168                                          ptr, &__x);            \
 169                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 170                 break;                                          \
 171         };                                                      \
 172         default:                                                \
 173                 __get_user_bad();                               \
 174                 break;                                          \
 175         }                                                       \
 176         __gu_err;                                               \
 177 })
 178
 179 #define get_user(x, ptr)                                        \
 180 ({                                                              \
 181         might_sleep();                                          \
 182         __get_user(x, ptr);                                     \
 183 })
 184
 185 extern int __get_user_bad(void) __attribute__((noreturn));
 186
 187 #define __put_user_unaligned __put_user
 188 #define __get_user_unaligned __get_user
 189
 190 /**
 191  * __copy_to_user: - Copy a block of data into user space, with less checking.
 192  * @to:   Destination address, in user space.
 193  * @from: Source address, in kernel space.
 194  * @n:    Number of bytes to copy.
 195  *
 196  * Context: User context only.  This function may sleep.
 197  *
 198  * Copy data from kernel space to user space.  Caller must check
 199  * the specified block with access_ok() before calling this function.
 200  *
 201  * Returns number of bytes that could not be copied.
 202  * On success, this will be zero.
 203  */
 204 static inline unsigned long
 205 __copy_to_user(void __user *to, const void *from, unsigned long n)
 206 {
 207         if (__builtin_constant_p(n) && (n <= 256))
 208                 return uaccess.copy_to_user_small(n, to, from);
 209         else
 210                 return uaccess.copy_to_user(n, to, from);
 211 }
 212
 213 #define __copy_to_user_inatomic __copy_to_user
 214 #define __copy_from_user_inatomic __copy_from_user
 215
 216 /**
 217  * copy_to_user: - Copy a block of data into user space.
 218  * @to:   Destination address, in user space.
 219  * @from: Source address, in kernel space.
 220  * @n:    Number of bytes to copy.
 221  *
 222  * Context: User context only.  This function may sleep.
 223  *
 224  * Copy data from kernel space to user space.
 225  *
 226  * Returns number of bytes that could not be copied.
 227  * On success, this will be zero.
 228  */
 229 static inline unsigned long
 230 copy_to_user(void __user *to, const void *from, unsigned long n)
 231 {
 232         might_sleep();
 233         if (access_ok(VERIFY_WRITE, to, n))
 234                 n = __copy_to_user(to, from, n);
 235         return n;
 236 }
 237
 238 /**
 239  * __copy_from_user: - Copy a block of data from user space, with less checking.
 240  * @to:   Destination address, in kernel space.
 241  * @from: Source address, in user space.
 242  * @n:    Number of bytes to copy.
 243  *
 244  * Context: User context only.  This function may sleep.
 245  *
 246  * Copy data from user space to kernel space.  Caller must check
 247  * the specified block with access_ok() before calling this function.
 248  *
 249  * Returns number of bytes that could not be copied.
 250  * On success, this will be zero.
 251  *
 252  * If some data could not be copied, this function will pad the copied
 253  * data to the requested size using zero bytes.
 254  */
 255 static inline unsigned long
 256 __copy_from_user(void *to, const void __user *from, unsigned long n)
 257 {
 258         if (__builtin_constant_p(n) && (n <= 256))
 259                 return uaccess.copy_from_user_small(n, from, to);
 260         else
 261                 return uaccess.copy_from_user(n, from, to);
 262 }
 263
 264 /**
 265  * copy_from_user: - Copy a block of data from user space.
 266  * @to:   Destination address, in kernel space.
 267  * @from: Source address, in user space.
 268  * @n:    Number of bytes to copy.
 269  *
 270  * Context: User context only.  This function may sleep.
 271  *
 272  * Copy data from user space to kernel space.
 273  *
 274  * Returns number of bytes that could not be copied.
 275  * On success, this will be zero.
 276  *
 277  * If some data could not be copied, this function will pad the copied
 278  * data to the requested size using zero bytes.
 279  */
 280 static inline unsigned long
 281 copy_from_user(void *to, const void __user *from, unsigned long n)
 282 {
 283         might_sleep();
 284         if (access_ok(VERIFY_READ, from, n))
 285                 n = __copy_from_user(to, from, n);
 286         else
 287                 memset(to, 0, n);
 288         return n;
 289 }
 290
 291 static inline unsigned long
 292 __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 293 {
 294         return uaccess.copy_in_user(n, to, from);
 295 }
 296
 297 static inline unsigned long
 298 copy_in_user(void __user *to, const void __user *from, unsigned long n)
 299 {
 300         might_sleep();
 301         if (__access_ok(from,n) && __access_ok(to,n))
 302                 n = __copy_in_user(to, from, n);
 303         return n;
 304 }
 305
 306 /*
 307  * Copy a null terminated string from userspace.
 308  */
 309 static inline long
 310 strncpy_from_user(char *dst, const char __user *src, long count)
 311 {
 312         long res = -EFAULT;
 313         might_sleep();
 314         if (access_ok(VERIFY_READ, src, 1))
 315                 res = uaccess.strncpy_from_user(count, src, dst);
 316         return res;
 317 }
 318
 319 static inline unsigned long
 320 strnlen_user(const char __user * src, unsigned long n)
 321 {
 322         might_sleep();
 323         return uaccess.strnlen_user(n, src);
 324 }
 325
 326 /**
 327  * strlen_user: - Get the size of a string in user space.
 328  * @str: The string to measure.
 329  *
 330  * Context: User context only.  This function may sleep.
 331  *
 332  * Get the size of a NUL-terminated string in user space.
 333  *
 334  * Returns the size of the string INCLUDING the terminating NUL.
 335  * On exception, returns 0.
 336  *
 337  * If there is a limit on the length of a valid string, you may wish to
 338  * consider using strnlen_user() instead.
 339  */
 340 #define strlen_user(str) strnlen_user(str, ~0UL)
 341
 342 /*
 343  * Zero Userspace
 344  */
 345
 346 static inline unsigned long
 347 __clear_user(void __user *to, unsigned long n)
 348 {
 349         return uaccess.clear_user(n, to);
 350 }
 351
 352 static inline unsigned long
 353 clear_user(void __user *to, unsigned long n)
 354 {
 355         might_sleep();
 356         if (access_ok(VERIFY_WRITE, to, n))
 357                 n = uaccess.clear_user(n, to);
 358         return n;
 359 }
 360
 361 #endif /* __S390_UACCESS_H */