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 #include <asm/ctl_reg.h>
  20
  21 #define VERIFY_READ     0
  22 #define VERIFY_WRITE    1
  23
  24
  25 /*
  26  * The fs value determines whether argument validity checking should be
  27  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  28  * get_fs() == KERNEL_DS, checking is bypassed.
  29  *
  30  * For historical reasons, these macros are grossly misnamed.
  31  */
  32
  33 #define MAKE_MM_SEG(a)  ((mm_segment_t) { (a) })
  34
  35
  36 #define KERNEL_DS       MAKE_MM_SEG(0)
  37 #define USER_DS         MAKE_MM_SEG(1)
  38
  39 #define get_ds()        (KERNEL_DS)
  40 #define get_fs()        (current->thread.mm_segment)
  41
  42 #define set_fs(x) \
  43 ({                                                                      \
  44         unsigned long __pto;                                            \
  45         current->thread.mm_segment = (x);                               \
  46         __pto = current->thread.mm_segment.ar4 ?                        \
  47                 S390_lowcore.user_asce : S390_lowcore.kernel_asce;      \
  48         __ctl_load(__pto, 7, 7);                                        \
  49 })
  50
  51 #define segment_eq(a,b) ((a).ar4 == (b).ar4)
  52
  53 static inline int __range_ok(unsigned long addr, unsigned long size)
  54 {
  55         return 1;
  56 }
  57
  58 #define __access_ok(addr, size)                         \
  59 ({                                                      \
  60         __chk_user_ptr(addr);                           \
  61         __range_ok((unsigned long)(addr), (size));      \
  62 })
  63
  64 #define access_ok(type, addr, size) __access_ok(addr, size)
  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 struct uaccess_ops {
  85         size_t (*copy_from_user)(size_t, const void __user *, void *);
  86         size_t (*copy_from_user_small)(size_t, const void __user *, void *);
  87         size_t (*copy_to_user)(size_t, void __user *, const void *);
  88         size_t (*copy_to_user_small)(size_t, void __user *, const void *);
  89         size_t (*copy_in_user)(size_t, void __user *, const void __user *);
  90         size_t (*clear_user)(size_t, void __user *);
  91         size_t (*strnlen_user)(size_t, const char __user *);
  92         size_t (*strncpy_from_user)(size_t, const char __user *, char *);
  93         int (*futex_atomic_op)(int op, u32 __user *, int oparg, int *old);
  94         int (*futex_atomic_cmpxchg)(u32 *, u32 __user *, u32 old, u32 new);
  95 };
  96
  97 extern struct uaccess_ops uaccess;
  98 extern struct uaccess_ops uaccess_std;
  99 extern struct uaccess_ops uaccess_mvcos;
 100 extern struct uaccess_ops uaccess_mvcos_switch;
 101 extern struct uaccess_ops uaccess_pt;
 102
 103 extern int __handle_fault(unsigned long, unsigned long, int);
 104
 105 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 106 {
 107         size = uaccess.copy_to_user_small(size, ptr, x);
 108         return size ? -EFAULT : size;
 109 }
 110
 111 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 112 {
 113         size = uaccess.copy_from_user_small(size, ptr, x);
 114         return size ? -EFAULT : size;
 115 }
 116
 117 /*
 118  * These are the main single-value transfer routines.  They automatically
 119  * use the right size if we just have the right pointer type.
 120  */
 121 #define __put_user(x, ptr) \
 122 ({                                                              \
 123         __typeof__(*(ptr)) __x = (x);                           \
 124         int __pu_err = -EFAULT;                                 \
 125         __chk_user_ptr(ptr);                                    \
 126         switch (sizeof (*(ptr))) {                              \
 127         case 1:                                                 \
 128         case 2:                                                 \
 129         case 4:                                                 \
 130         case 8:                                                 \
 131                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 132                                          ptr, &__x);            \
 133                 break;                                          \
 134         default:                                                \
 135                 __put_user_bad();                               \
 136                 break;                                          \
 137          }                                                      \
 138         __pu_err;                                               \
 139 })
 140
 141 #define put_user(x, ptr)                                        \
 142 ({                                                              \
 143         might_fault();                                          \
 144         __put_user(x, ptr);                                     \
 145 })
 146
 147
 148 extern int __put_user_bad(void) __attribute__((noreturn));
 149
 150 #define __get_user(x, ptr)                                      \
 151 ({                                                              \
 152         int __gu_err = -EFAULT;                                 \
 153         __chk_user_ptr(ptr);                                    \
 154         switch (sizeof(*(ptr))) {                               \
 155         case 1: {                                               \
 156                 unsigned char __x;                              \
 157                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 158                                          ptr, &__x);            \
 159                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 160                 break;                                          \
 161         };                                                      \
 162         case 2: {                                               \
 163                 unsigned short __x;                             \
 164                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 165                                          ptr, &__x);            \
 166                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 167                 break;                                          \
 168         };                                                      \
 169         case 4: {                                               \
 170                 unsigned int __x;                               \
 171                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 172                                          ptr, &__x);            \
 173                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 174                 break;                                          \
 175         };                                                      \
 176         case 8: {                                               \
 177                 unsigned long long __x;                         \
 178                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 179                                          ptr, &__x);            \
 180                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 181                 break;                                          \
 182         };                                                      \
 183         default:                                                \
 184                 __get_user_bad();                               \
 185                 break;                                          \
 186         }                                                       \
 187         __gu_err;                                               \
 188 })
 189
 190 #define get_user(x, ptr)                                        \
 191 ({                                                              \
 192         might_fault();                                          \
 193         __get_user(x, ptr);                                     \
 194 })
 195
 196 extern int __get_user_bad(void) __attribute__((noreturn));
 197
 198 #define __put_user_unaligned __put_user
 199 #define __get_user_unaligned __get_user
 200
 201 /**
 202  * __copy_to_user: - Copy a block of data into user space, with less checking.
 203  * @to:   Destination address, in user space.
 204  * @from: Source address, in kernel space.
 205  * @n:    Number of bytes to copy.
 206  *
 207  * Context: User context only.  This function may sleep.
 208  *
 209  * Copy data from kernel space to user space.  Caller must check
 210  * the specified block with access_ok() before calling this function.
 211  *
 212  * Returns number of bytes that could not be copied.
 213  * On success, this will be zero.
 214  */
 215 static inline unsigned long __must_check
 216 __copy_to_user(void __user *to, const void *from, unsigned long n)
 217 {
 218         if (__builtin_constant_p(n) && (n <= 256))
 219                 return uaccess.copy_to_user_small(n, to, from);
 220         else
 221                 return uaccess.copy_to_user(n, to, from);
 222 }
 223
 224 #define __copy_to_user_inatomic __copy_to_user
 225 #define __copy_from_user_inatomic __copy_from_user
 226
 227 /**
 228  * copy_to_user: - Copy a block of data into user space.
 229  * @to:   Destination address, in user space.
 230  * @from: Source address, in kernel space.
 231  * @n:    Number of bytes to copy.
 232  *
 233  * Context: User context only.  This function may sleep.
 234  *
 235  * Copy data from kernel space to user space.
 236  *
 237  * Returns number of bytes that could not be copied.
 238  * On success, this will be zero.
 239  */
 240 static inline unsigned long __must_check
 241 copy_to_user(void __user *to, const void *from, unsigned long n)
 242 {
 243         might_fault();
 244         if (access_ok(VERIFY_WRITE, to, n))
 245                 n = __copy_to_user(to, from, n);
 246         return n;
 247 }
 248
 249 /**
 250  * __copy_from_user: - Copy a block of data from user space, with less checking.
 251  * @to:   Destination address, in kernel space.
 252  * @from: Source address, in user space.
 253  * @n:    Number of bytes to copy.
 254  *
 255  * Context: User context only.  This function may sleep.
 256  *
 257  * Copy data from user space to kernel space.  Caller must check
 258  * the specified block with access_ok() before calling this function.
 259  *
 260  * Returns number of bytes that could not be copied.
 261  * On success, this will be zero.
 262  *
 263  * If some data could not be copied, this function will pad the copied
 264  * data to the requested size using zero bytes.
 265  */
 266 static inline unsigned long __must_check
 267 __copy_from_user(void *to, const void __user *from, unsigned long n)
 268 {
 269         if (__builtin_constant_p(n) && (n <= 256))
 270                 return uaccess.copy_from_user_small(n, from, to);
 271         else
 272                 return uaccess.copy_from_user(n, from, to);
 273 }
 274
 275 extern void copy_from_user_overflow(void)
 276 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 277 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 278 #endif
 279 ;
 280
 281 /**
 282  * copy_from_user: - Copy a block of data from user space.
 283  * @to:   Destination address, in kernel space.
 284  * @from: Source address, in user space.
 285  * @n:    Number of bytes to copy.
 286  *
 287  * Context: User context only.  This function may sleep.
 288  *
 289  * Copy data from user space to kernel space.
 290  *
 291  * Returns number of bytes that could not be copied.
 292  * On success, this will be zero.
 293  *
 294  * If some data could not be copied, this function will pad the copied
 295  * data to the requested size using zero bytes.
 296  */
 297 static inline unsigned long __must_check
 298 copy_from_user(void *to, const void __user *from, unsigned long n)
 299 {
 300         unsigned int sz = __compiletime_object_size(to);
 301
 302         might_fault();
 303         if (unlikely(sz != -1 && sz < n)) {
 304                 copy_from_user_overflow();
 305                 return n;
 306         }
 307         if (access_ok(VERIFY_READ, from, n))
 308                 n = __copy_from_user(to, from, n);
 309         else
 310                 memset(to, 0, n);
 311         return n;
 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         return uaccess.copy_in_user(n, to, from);
 318 }
 319
 320 static inline unsigned long __must_check
 321 copy_in_user(void __user *to, const void __user *from, unsigned long n)
 322 {
 323         might_fault();
 324         if (__access_ok(from,n) && __access_ok(to,n))
 325                 n = __copy_in_user(to, from, n);
 326         return n;
 327 }
 328
 329 /*
 330  * Copy a null terminated string from userspace.
 331  */
 332 static inline long __must_check
 333 strncpy_from_user(char *dst, const char __user *src, long count)
 334 {
 335         long res = -EFAULT;
 336         might_fault();
 337         if (access_ok(VERIFY_READ, src, 1))
 338                 res = uaccess.strncpy_from_user(count, src, dst);
 339         return res;
 340 }
 341
 342 static inline unsigned long
 343 strnlen_user(const char __user * src, unsigned long n)
 344 {
 345         might_fault();
 346         return uaccess.strnlen_user(n, src);
 347 }
 348
 349 /**
 350  * strlen_user: - Get the size of a string in user space.
 351  * @str: The string to measure.
 352  *
 353  * Context: User context only.  This function may sleep.
 354  *
 355  * Get the size of a NUL-terminated string in user space.
 356  *
 357  * Returns the size of the string INCLUDING the terminating NUL.
 358  * On exception, returns 0.
 359  *
 360  * If there is a limit on the length of a valid string, you may wish to
 361  * consider using strnlen_user() instead.
 362  */
 363 #define strlen_user(str) strnlen_user(str, ~0UL)
 364
 365 /*
 366  * Zero Userspace
 367  */
 368
 369 static inline unsigned long __must_check
 370 __clear_user(void __user *to, unsigned long n)
 371 {
 372         return uaccess.clear_user(n, to);
 373 }
 374
 375 static inline unsigned long __must_check
 376 clear_user(void __user *to, unsigned long n)
 377 {
 378         might_fault();
 379         if (access_ok(VERIFY_WRITE, to, n))
 380                 n = uaccess.clear_user(n, to);
 381         return n;
 382 }
 383
 384 extern int memcpy_real(void *, void *, size_t);
 385 extern void memcpy_absolute(void *, void *, size_t);
 386 extern int copy_to_user_real(void __user *dest, void *src, size_t count);
 387 extern int copy_from_user_real(void *dest, void __user *src, size_t count);
 388
 389 #endif /* __S390_UACCESS_H */