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 #define __access_ok(addr, size) \
  53 ({                              \
  54         __chk_user_ptr(addr);   \
  55         1;                      \
  56 })
  57
  58 #define access_ok(type, addr, size) __access_ok(addr, size)
  59
  60 /*
  61  * The exception table consists of pairs of addresses: the first is the
  62  * address of an instruction that is allowed to fault, and the second is
  63  * the address at which the program should continue.  No registers are
  64  * modified, so it is entirely up to the continuation code to figure out
  65  * what to do.
  66  *
  67  * All the routines below use bits of fixup code that are out of line
  68  * with the main instruction path.  This means when everything is well,
  69  * we don't even have to jump over them.  Further, they do not intrude
  70  * on our cache or tlb entries.
  71  */
  72
  73 struct exception_table_entry
  74 {
  75         unsigned long insn, fixup;
  76 };
  77
  78 struct uaccess_ops {
  79         size_t (*copy_from_user)(size_t, const void __user *, void *);
  80         size_t (*copy_from_user_small)(size_t, const void __user *, void *);
  81         size_t (*copy_to_user)(size_t, void __user *, const void *);
  82         size_t (*copy_to_user_small)(size_t, void __user *, const void *);
  83         size_t (*copy_in_user)(size_t, void __user *, const void __user *);
  84         size_t (*clear_user)(size_t, void __user *);
  85         size_t (*strnlen_user)(size_t, const char __user *);
  86         size_t (*strncpy_from_user)(size_t, const char __user *, char *);
  87         int (*futex_atomic_op)(int op, u32 __user *, int oparg, int *old);
  88         int (*futex_atomic_cmpxchg)(u32 *, u32 __user *, u32 old, u32 new);
  89 };
  90
  91 extern struct uaccess_ops uaccess;
  92 extern struct uaccess_ops uaccess_std;
  93 extern struct uaccess_ops uaccess_mvcos;
  94 extern struct uaccess_ops uaccess_mvcos_switch;
  95 extern struct uaccess_ops uaccess_pt;
  96
  97 extern int __handle_fault(unsigned long, unsigned long, int);
  98
  99 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 100 {
 101         size = uaccess.copy_to_user_small(size, ptr, x);
 102         return size ? -EFAULT : size;
 103 }
 104
 105 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 106 {
 107         size = uaccess.copy_from_user_small(size, ptr, x);
 108         return size ? -EFAULT : size;
 109 }
 110
 111 /*
 112  * These are the main single-value transfer routines.  They automatically
 113  * use the right size if we just have the right pointer type.
 114  */
 115 #define __put_user(x, ptr) \
 116 ({                                                              \
 117         __typeof__(*(ptr)) __x = (x);                           \
 118         int __pu_err = -EFAULT;                                 \
 119         __chk_user_ptr(ptr);                                    \
 120         switch (sizeof (*(ptr))) {                              \
 121         case 1:                                                 \
 122         case 2:                                                 \
 123         case 4:                                                 \
 124         case 8:                                                 \
 125                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 126                                          ptr, &__x);            \
 127                 break;                                          \
 128         default:                                                \
 129                 __put_user_bad();                               \
 130                 break;                                          \
 131          }                                                      \
 132         __pu_err;                                               \
 133 })
 134
 135 #define put_user(x, ptr)                                        \
 136 ({                                                              \
 137         might_fault();                                          \
 138         __put_user(x, ptr);                                     \
 139 })
 140
 141
 142 extern int __put_user_bad(void) __attribute__((noreturn));
 143
 144 #define __get_user(x, ptr)                                      \
 145 ({                                                              \
 146         int __gu_err = -EFAULT;                                 \
 147         __chk_user_ptr(ptr);                                    \
 148         switch (sizeof(*(ptr))) {                               \
 149         case 1: {                                               \
 150                 unsigned char __x;                              \
 151                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 152                                          ptr, &__x);            \
 153                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 154                 break;                                          \
 155         };                                                      \
 156         case 2: {                                               \
 157                 unsigned short __x;                             \
 158                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 159                                          ptr, &__x);            \
 160                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 161                 break;                                          \
 162         };                                                      \
 163         case 4: {                                               \
 164                 unsigned int __x;                               \
 165                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 166                                          ptr, &__x);            \
 167                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 168                 break;                                          \
 169         };                                                      \
 170         case 8: {                                               \
 171                 unsigned long long __x;                         \
 172                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 173                                          ptr, &__x);            \
 174                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 175                 break;                                          \
 176         };                                                      \
 177         default:                                                \
 178                 __get_user_bad();                               \
 179                 break;                                          \
 180         }                                                       \
 181         __gu_err;                                               \
 182 })
 183
 184 #define get_user(x, ptr)                                        \
 185 ({                                                              \
 186         might_fault();                                          \
 187         __get_user(x, ptr);                                     \
 188 })
 189
 190 extern int __get_user_bad(void) __attribute__((noreturn));
 191
 192 #define __put_user_unaligned __put_user
 193 #define __get_user_unaligned __get_user
 194
 195 /**
 196  * __copy_to_user: - Copy a block of data into user space, with less checking.
 197  * @to:   Destination address, in user space.
 198  * @from: Source address, in kernel space.
 199  * @n:    Number of bytes to copy.
 200  *
 201  * Context: User context only.  This function may sleep.
 202  *
 203  * Copy data from kernel space to user space.  Caller must check
 204  * the specified block with access_ok() before calling this function.
 205  *
 206  * Returns number of bytes that could not be copied.
 207  * On success, this will be zero.
 208  */
 209 static inline unsigned long __must_check
 210 __copy_to_user(void __user *to, const void *from, unsigned long n)
 211 {
 212         if (__builtin_constant_p(n) && (n <= 256))
 213                 return uaccess.copy_to_user_small(n, to, from);
 214         else
 215                 return uaccess.copy_to_user(n, to, from);
 216 }
 217
 218 #define __copy_to_user_inatomic __copy_to_user
 219 #define __copy_from_user_inatomic __copy_from_user
 220
 221 /**
 222  * copy_to_user: - Copy a block of data into user space.
 223  * @to:   Destination address, in user space.
 224  * @from: Source address, in kernel space.
 225  * @n:    Number of bytes to copy.
 226  *
 227  * Context: User context only.  This function may sleep.
 228  *
 229  * Copy data from kernel space to user space.
 230  *
 231  * Returns number of bytes that could not be copied.
 232  * On success, this will be zero.
 233  */
 234 static inline unsigned long __must_check
 235 copy_to_user(void __user *to, const void *from, unsigned long n)
 236 {
 237         might_fault();
 238         if (access_ok(VERIFY_WRITE, to, n))
 239                 n = __copy_to_user(to, from, n);
 240         return n;
 241 }
 242
 243 /**
 244  * __copy_from_user: - Copy a block of data from user space, with less checking.
 245  * @to:   Destination address, in kernel space.
 246  * @from: Source address, in user space.
 247  * @n:    Number of bytes to copy.
 248  *
 249  * Context: User context only.  This function may sleep.
 250  *
 251  * Copy data from user space to kernel space.  Caller must check
 252  * the specified block with access_ok() before calling this function.
 253  *
 254  * Returns number of bytes that could not be copied.
 255  * On success, this will be zero.
 256  *
 257  * If some data could not be copied, this function will pad the copied
 258  * data to the requested size using zero bytes.
 259  */
 260 static inline unsigned long __must_check
 261 __copy_from_user(void *to, const void __user *from, unsigned long n)
 262 {
 263         if (__builtin_constant_p(n) && (n <= 256))
 264                 return uaccess.copy_from_user_small(n, from, to);
 265         else
 266                 return uaccess.copy_from_user(n, from, to);
 267 }
 268
 269 extern void copy_from_user_overflow(void)
 270 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 271 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 272 #endif
 273 ;
 274
 275 /**
 276  * copy_from_user: - Copy a block of data from user space.
 277  * @to:   Destination address, in kernel space.
 278  * @from: Source address, in user space.
 279  * @n:    Number of bytes to copy.
 280  *
 281  * Context: User context only.  This function may sleep.
 282  *
 283  * Copy data from user space to kernel space.
 284  *
 285  * Returns number of bytes that could not be copied.
 286  * On success, this will be zero.
 287  *
 288  * If some data could not be copied, this function will pad the copied
 289  * data to the requested size using zero bytes.
 290  */
 291 static inline unsigned long __must_check
 292 copy_from_user(void *to, const void __user *from, unsigned long n)
 293 {
 294         unsigned int sz = __compiletime_object_size(to);
 295
 296         might_fault();
 297         if (unlikely(sz != -1 && sz < n)) {
 298                 copy_from_user_overflow();
 299                 return n;
 300         }
 301         if (access_ok(VERIFY_READ, from, n))
 302                 n = __copy_from_user(to, from, n);
 303         else
 304                 memset(to, 0, n);
 305         return n;
 306 }
 307
 308 static inline unsigned long __must_check
 309 __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 310 {
 311         return uaccess.copy_in_user(n, to, from);
 312 }
 313
 314 static inline unsigned long __must_check
 315 copy_in_user(void __user *to, const void __user *from, unsigned long n)
 316 {
 317         might_fault();
 318         if (__access_ok(from,n) && __access_ok(to,n))
 319                 n = __copy_in_user(to, from, n);
 320         return n;
 321 }
 322
 323 /*
 324  * Copy a null terminated string from userspace.
 325  */
 326 static inline long __must_check
 327 strncpy_from_user(char *dst, const char __user *src, long count)
 328 {
 329         long res = -EFAULT;
 330         might_fault();
 331         if (access_ok(VERIFY_READ, src, 1))
 332                 res = uaccess.strncpy_from_user(count, src, dst);
 333         return res;
 334 }
 335
 336 static inline unsigned long
 337 strnlen_user(const char __user * src, unsigned long n)
 338 {
 339         might_fault();
 340         return uaccess.strnlen_user(n, src);
 341 }
 342
 343 /**
 344  * strlen_user: - Get the size of a string in user space.
 345  * @str: The string to measure.
 346  *
 347  * Context: User context only.  This function may sleep.
 348  *
 349  * Get the size of a NUL-terminated string in user space.
 350  *
 351  * Returns the size of the string INCLUDING the terminating NUL.
 352  * On exception, returns 0.
 353  *
 354  * If there is a limit on the length of a valid string, you may wish to
 355  * consider using strnlen_user() instead.
 356  */
 357 #define strlen_user(str) strnlen_user(str, ~0UL)
 358
 359 /*
 360  * Zero Userspace
 361  */
 362
 363 static inline unsigned long __must_check
 364 __clear_user(void __user *to, unsigned long n)
 365 {
 366         return uaccess.clear_user(n, to);
 367 }
 368
 369 static inline unsigned long __must_check
 370 clear_user(void __user *to, unsigned long n)
 371 {
 372         might_fault();
 373         if (access_ok(VERIFY_WRITE, to, n))
 374                 n = uaccess.clear_user(n, to);
 375         return n;
 376 }
 377
 378 #endif /* __S390_UACCESS_H */