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 __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 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
  97 {
  98         size = uaccess.copy_to_user_small(size, ptr, x);
  99         return size ? -EFAULT : size;
 100 }
 101
 102 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 103 {
 104         size = uaccess.copy_from_user_small(size, ptr, x);
 105         return size ? -EFAULT : size;
 106 }
 107
 108 /*
 109  * These are the main single-value transfer routines.  They automatically
 110  * use the right size if we just have the right pointer type.
 111  */
 112 #define __put_user(x, ptr) \
 113 ({                                                              \
 114         __typeof__(*(ptr)) __x = (x);                           \
 115         int __pu_err = -EFAULT;                                 \
 116         __chk_user_ptr(ptr);                                    \
 117         switch (sizeof (*(ptr))) {                              \
 118         case 1:                                                 \
 119         case 2:                                                 \
 120         case 4:                                                 \
 121         case 8:                                                 \
 122                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 123                                          ptr, &__x);            \
 124                 break;                                          \
 125         default:                                                \
 126                 __put_user_bad();                               \
 127                 break;                                          \
 128          }                                                      \
 129         __pu_err;                                               \
 130 })
 131
 132 #define put_user(x, ptr)                                        \
 133 ({                                                              \
 134         might_fault();                                          \
 135         __put_user(x, ptr);                                     \
 136 })
 137
 138
 139 extern int __put_user_bad(void) __attribute__((noreturn));
 140
 141 #define __get_user(x, ptr)                                      \
 142 ({                                                              \
 143         int __gu_err = -EFAULT;                                 \
 144         __chk_user_ptr(ptr);                                    \
 145         switch (sizeof(*(ptr))) {                               \
 146         case 1: {                                               \
 147                 unsigned char __x;                              \
 148                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 149                                          ptr, &__x);            \
 150                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 151                 break;                                          \
 152         };                                                      \
 153         case 2: {                                               \
 154                 unsigned short __x;                             \
 155                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 156                                          ptr, &__x);            \
 157                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 158                 break;                                          \
 159         };                                                      \
 160         case 4: {                                               \
 161                 unsigned int __x;                               \
 162                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 163                                          ptr, &__x);            \
 164                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 165                 break;                                          \
 166         };                                                      \
 167         case 8: {                                               \
 168                 unsigned long long __x;                         \
 169                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 170                                          ptr, &__x);            \
 171                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 172                 break;                                          \
 173         };                                                      \
 174         default:                                                \
 175                 __get_user_bad();                               \
 176                 break;                                          \
 177         }                                                       \
 178         __gu_err;                                               \
 179 })
 180
 181 #define get_user(x, ptr)                                        \
 182 ({                                                              \
 183         might_fault();                                          \
 184         __get_user(x, ptr);                                     \
 185 })
 186
 187 extern int __get_user_bad(void) __attribute__((noreturn));
 188
 189 #define __put_user_unaligned __put_user
 190 #define __get_user_unaligned __get_user
 191
 192 /**
 193  * __copy_to_user: - Copy a block of data into user space, with less checking.
 194  * @to:   Destination address, in user space.
 195  * @from: Source address, in kernel space.
 196  * @n:    Number of bytes to copy.
 197  *
 198  * Context: User context only.  This function may sleep.
 199  *
 200  * Copy data from kernel space to user space.  Caller must check
 201  * the specified block with access_ok() before calling this function.
 202  *
 203  * Returns number of bytes that could not be copied.
 204  * On success, this will be zero.
 205  */
 206 static inline unsigned long __must_check
 207 __copy_to_user(void __user *to, const void *from, unsigned long n)
 208 {
 209         if (__builtin_constant_p(n) && (n <= 256))
 210                 return uaccess.copy_to_user_small(n, to, from);
 211         else
 212                 return uaccess.copy_to_user(n, to, from);
 213 }
 214
 215 #define __copy_to_user_inatomic __copy_to_user
 216 #define __copy_from_user_inatomic __copy_from_user
 217
 218 /**
 219  * copy_to_user: - Copy a block of data into user space.
 220  * @to:   Destination address, in user space.
 221  * @from: Source address, in kernel space.
 222  * @n:    Number of bytes to copy.
 223  *
 224  * Context: User context only.  This function may sleep.
 225  *
 226  * Copy data from kernel space to user space.
 227  *
 228  * Returns number of bytes that could not be copied.
 229  * On success, this will be zero.
 230  */
 231 static inline unsigned long __must_check
 232 copy_to_user(void __user *to, const void *from, unsigned long n)
 233 {
 234         might_fault();
 235         if (access_ok(VERIFY_WRITE, to, n))
 236                 n = __copy_to_user(to, from, n);
 237         return n;
 238 }
 239
 240 /**
 241  * __copy_from_user: - Copy a block of data from user space, with less checking.
 242  * @to:   Destination address, in kernel space.
 243  * @from: Source address, in user space.
 244  * @n:    Number of bytes to copy.
 245  *
 246  * Context: User context only.  This function may sleep.
 247  *
 248  * Copy data from user space to kernel space.  Caller must check
 249  * the specified block with access_ok() before calling this function.
 250  *
 251  * Returns number of bytes that could not be copied.
 252  * On success, this will be zero.
 253  *
 254  * If some data could not be copied, this function will pad the copied
 255  * data to the requested size using zero bytes.
 256  */
 257 static inline unsigned long __must_check
 258 __copy_from_user(void *to, const void __user *from, unsigned long n)
 259 {
 260         if (__builtin_constant_p(n) && (n <= 256))
 261                 return uaccess.copy_from_user_small(n, from, to);
 262         else
 263                 return uaccess.copy_from_user(n, from, to);
 264 }
 265
 266 /**
 267  * copy_from_user: - Copy a block of data from user space.
 268  * @to:   Destination address, in kernel space.
 269  * @from: Source address, in user space.
 270  * @n:    Number of bytes to copy.
 271  *
 272  * Context: User context only.  This function may sleep.
 273  *
 274  * Copy data from user space to kernel space.
 275  *
 276  * Returns number of bytes that could not be copied.
 277  * On success, this will be zero.
 278  *
 279  * If some data could not be copied, this function will pad the copied
 280  * data to the requested size using zero bytes.
 281  */
 282 static inline unsigned long __must_check
 283 copy_from_user(void *to, const void __user *from, unsigned long n)
 284 {
 285         might_fault();
 286         if (access_ok(VERIFY_READ, from, n))
 287                 n = __copy_from_user(to, from, n);
 288         else
 289                 memset(to, 0, n);
 290         return n;
 291 }
 292
 293 static inline unsigned long __must_check
 294 __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 295 {
 296         return uaccess.copy_in_user(n, to, from);
 297 }
 298
 299 static inline unsigned long __must_check
 300 copy_in_user(void __user *to, const void __user *from, unsigned long n)
 301 {
 302         might_fault();
 303         if (__access_ok(from,n) && __access_ok(to,n))
 304                 n = __copy_in_user(to, from, n);
 305         return n;
 306 }
 307
 308 /*
 309  * Copy a null terminated string from userspace.
 310  */
 311 static inline long __must_check
 312 strncpy_from_user(char *dst, const char __user *src, long count)
 313 {
 314         long res = -EFAULT;
 315         might_fault();
 316         if (access_ok(VERIFY_READ, src, 1))
 317                 res = uaccess.strncpy_from_user(count, src, dst);
 318         return res;
 319 }
 320
 321 static inline unsigned long
 322 strnlen_user(const char __user * src, unsigned long n)
 323 {
 324         might_fault();
 325         return uaccess.strnlen_user(n, src);
 326 }
 327
 328 /**
 329  * strlen_user: - Get the size of a string in user space.
 330  * @str: The string to measure.
 331  *
 332  * Context: User context only.  This function may sleep.
 333  *
 334  * Get the size of a NUL-terminated string in user space.
 335  *
 336  * Returns the size of the string INCLUDING the terminating NUL.
 337  * On exception, returns 0.
 338  *
 339  * If there is a limit on the length of a valid string, you may wish to
 340  * consider using strnlen_user() instead.
 341  */
 342 #define strlen_user(str) strnlen_user(str, ~0UL)
 343
 344 /*
 345  * Zero Userspace
 346  */
 347
 348 static inline unsigned long __must_check
 349 __clear_user(void __user *to, unsigned long n)
 350 {
 351         return uaccess.clear_user(n, to);
 352 }
 353
 354 static inline unsigned long __must_check
 355 clear_user(void __user *to, unsigned long n)
 356 {
 357         might_fault();
 358         if (access_ok(VERIFY_WRITE, to, n))
 359                 n = uaccess.clear_user(n, to);
 360         return n;
 361 }
 362
 363 #endif /* __S390_UACCESS_H */