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 #define __access_ok(addr, size) \
  54 ({                              \
  55         __chk_user_ptr(addr);   \
  56         1;                      \
  57 })
  58
  59 #define access_ok(type, addr, size) __access_ok(addr, size)
  60
  61 /*
  62  * The exception table consists of pairs of addresses: the first is the
  63  * address of an instruction that is allowed to fault, and the second is
  64  * the address at which the program should continue.  No registers are
  65  * modified, so it is entirely up to the continuation code to figure out
  66  * what to do.
  67  *
  68  * All the routines below use bits of fixup code that are out of line
  69  * with the main instruction path.  This means when everything is well,
  70  * we don't even have to jump over them.  Further, they do not intrude
  71  * on our cache or tlb entries.
  72  */
  73
  74 struct exception_table_entry
  75 {
  76         unsigned long insn, fixup;
  77 };
  78
  79 struct uaccess_ops {
  80         size_t (*copy_from_user)(size_t, const void __user *, void *);
  81         size_t (*copy_from_user_small)(size_t, const void __user *, void *);
  82         size_t (*copy_to_user)(size_t, void __user *, const void *);
  83         size_t (*copy_to_user_small)(size_t, void __user *, const void *);
  84         size_t (*copy_in_user)(size_t, void __user *, const void __user *);
  85         size_t (*clear_user)(size_t, void __user *);
  86         size_t (*strnlen_user)(size_t, const char __user *);
  87         size_t (*strncpy_from_user)(size_t, const char __user *, char *);
  88         int (*futex_atomic_op)(int op, u32 __user *, int oparg, int *old);
  89         int (*futex_atomic_cmpxchg)(u32 *, u32 __user *, u32 old, u32 new);
  90 };
  91
  92 extern struct uaccess_ops uaccess;
  93 extern struct uaccess_ops uaccess_std;
  94 extern struct uaccess_ops uaccess_mvcos;
  95 extern struct uaccess_ops uaccess_mvcos_switch;
  96 extern struct uaccess_ops uaccess_pt;
  97
  98 extern int __handle_fault(unsigned long, unsigned long, int);
  99
 100 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 101 {
 102         size = uaccess.copy_to_user_small(size, ptr, x);
 103         return size ? -EFAULT : size;
 104 }
 105
 106 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 107 {
 108         size = uaccess.copy_from_user_small(size, ptr, x);
 109         return size ? -EFAULT : size;
 110 }
 111
 112 /*
 113  * These are the main single-value transfer routines.  They automatically
 114  * use the right size if we just have the right pointer type.
 115  */
 116 #define __put_user(x, ptr) \
 117 ({                                                              \
 118         __typeof__(*(ptr)) __x = (x);                           \
 119         int __pu_err = -EFAULT;                                 \
 120         __chk_user_ptr(ptr);                                    \
 121         switch (sizeof (*(ptr))) {                              \
 122         case 1:                                                 \
 123         case 2:                                                 \
 124         case 4:                                                 \
 125         case 8:                                                 \
 126                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 127                                          ptr, &__x);            \
 128                 break;                                          \
 129         default:                                                \
 130                 __put_user_bad();                               \
 131                 break;                                          \
 132          }                                                      \
 133         __pu_err;                                               \
 134 })
 135
 136 #define put_user(x, ptr)                                        \
 137 ({                                                              \
 138         might_fault();                                          \
 139         __put_user(x, ptr);                                     \
 140 })
 141
 142
 143 extern int __put_user_bad(void) __attribute__((noreturn));
 144
 145 #define __get_user(x, ptr)                                      \
 146 ({                                                              \
 147         int __gu_err = -EFAULT;                                 \
 148         __chk_user_ptr(ptr);                                    \
 149         switch (sizeof(*(ptr))) {                               \
 150         case 1: {                                               \
 151                 unsigned char __x;                              \
 152                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 153                                          ptr, &__x);            \
 154                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 155                 break;                                          \
 156         };                                                      \
 157         case 2: {                                               \
 158                 unsigned short __x;                             \
 159                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 160                                          ptr, &__x);            \
 161                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 162                 break;                                          \
 163         };                                                      \
 164         case 4: {                                               \
 165                 unsigned int __x;                               \
 166                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 167                                          ptr, &__x);            \
 168                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 169                 break;                                          \
 170         };                                                      \
 171         case 8: {                                               \
 172                 unsigned long long __x;                         \
 173                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 174                                          ptr, &__x);            \
 175                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 176                 break;                                          \
 177         };                                                      \
 178         default:                                                \
 179                 __get_user_bad();                               \
 180                 break;                                          \
 181         }                                                       \
 182         __gu_err;                                               \
 183 })
 184
 185 #define get_user(x, ptr)                                        \
 186 ({                                                              \
 187         might_fault();                                          \
 188         __get_user(x, ptr);                                     \
 189 })
 190
 191 extern int __get_user_bad(void) __attribute__((noreturn));
 192
 193 #define __put_user_unaligned __put_user
 194 #define __get_user_unaligned __get_user
 195
 196 /**
 197  * __copy_to_user: - Copy a block of data into user space, with less checking.
 198  * @to:   Destination address, in user space.
 199  * @from: Source address, in kernel space.
 200  * @n:    Number of bytes to copy.
 201  *
 202  * Context: User context only.  This function may sleep.
 203  *
 204  * Copy data from kernel space to user space.  Caller must check
 205  * the specified block with access_ok() before calling this function.
 206  *
 207  * Returns number of bytes that could not be copied.
 208  * On success, this will be zero.
 209  */
 210 static inline unsigned long __must_check
 211 __copy_to_user(void __user *to, const void *from, unsigned long n)
 212 {
 213         if (__builtin_constant_p(n) && (n <= 256))
 214                 return uaccess.copy_to_user_small(n, to, from);
 215         else
 216                 return uaccess.copy_to_user(n, to, from);
 217 }
 218
 219 #define __copy_to_user_inatomic __copy_to_user
 220 #define __copy_from_user_inatomic __copy_from_user
 221
 222 /**
 223  * copy_to_user: - Copy a block of data into user space.
 224  * @to:   Destination address, in user space.
 225  * @from: Source address, in kernel space.
 226  * @n:    Number of bytes to copy.
 227  *
 228  * Context: User context only.  This function may sleep.
 229  *
 230  * Copy data from kernel space to user space.
 231  *
 232  * Returns number of bytes that could not be copied.
 233  * On success, this will be zero.
 234  */
 235 static inline unsigned long __must_check
 236 copy_to_user(void __user *to, const void *from, unsigned long n)
 237 {
 238         might_fault();
 239         if (access_ok(VERIFY_WRITE, to, n))
 240                 n = __copy_to_user(to, from, n);
 241         return n;
 242 }
 243
 244 /**
 245  * __copy_from_user: - Copy a block of data from user space, with less checking.
 246  * @to:   Destination address, in kernel space.
 247  * @from: Source address, in user space.
 248  * @n:    Number of bytes to copy.
 249  *
 250  * Context: User context only.  This function may sleep.
 251  *
 252  * Copy data from user space to kernel space.  Caller must check
 253  * the specified block with access_ok() before calling this function.
 254  *
 255  * Returns number of bytes that could not be copied.
 256  * On success, this will be zero.
 257  *
 258  * If some data could not be copied, this function will pad the copied
 259  * data to the requested size using zero bytes.
 260  */
 261 static inline unsigned long __must_check
 262 __copy_from_user(void *to, const void __user *from, unsigned long n)
 263 {
 264         if (__builtin_constant_p(n) && (n <= 256))
 265                 return uaccess.copy_from_user_small(n, from, to);
 266         else
 267                 return uaccess.copy_from_user(n, from, to);
 268 }
 269
 270 extern void copy_from_user_overflow(void)
 271 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 272 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 273 #endif
 274 ;
 275
 276 /**
 277  * copy_from_user: - Copy a block of data from user space.
 278  * @to:   Destination address, in kernel space.
 279  * @from: Source address, in user space.
 280  * @n:    Number of bytes to copy.
 281  *
 282  * Context: User context only.  This function may sleep.
 283  *
 284  * Copy data from user space to kernel space.
 285  *
 286  * Returns number of bytes that could not be copied.
 287  * On success, this will be zero.
 288  *
 289  * If some data could not be copied, this function will pad the copied
 290  * data to the requested size using zero bytes.
 291  */
 292 static inline unsigned long __must_check
 293 copy_from_user(void *to, const void __user *from, unsigned long n)
 294 {
 295         unsigned int sz = __compiletime_object_size(to);
 296
 297         might_fault();
 298         if (unlikely(sz != -1 && sz < n)) {
 299                 copy_from_user_overflow();
 300                 return n;
 301         }
 302         if (access_ok(VERIFY_READ, from, n))
 303                 n = __copy_from_user(to, from, n);
 304         else
 305                 memset(to, 0, n);
 306         return n;
 307 }
 308
 309 static inline unsigned long __must_check
 310 __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 311 {
 312         return uaccess.copy_in_user(n, to, from);
 313 }
 314
 315 static inline unsigned long __must_check
 316 copy_in_user(void __user *to, const void __user *from, unsigned long n)
 317 {
 318         might_fault();
 319         if (__access_ok(from,n) && __access_ok(to,n))
 320                 n = __copy_in_user(to, from, n);
 321         return n;
 322 }
 323
 324 /*
 325  * Copy a null terminated string from userspace.
 326  */
 327 static inline long __must_check
 328 strncpy_from_user(char *dst, const char __user *src, long count)
 329 {
 330         long res = -EFAULT;
 331         might_fault();
 332         if (access_ok(VERIFY_READ, src, 1))
 333                 res = uaccess.strncpy_from_user(count, src, dst);
 334         return res;
 335 }
 336
 337 static inline unsigned long
 338 strnlen_user(const char __user * src, unsigned long n)
 339 {
 340         might_fault();
 341         return uaccess.strnlen_user(n, src);
 342 }
 343
 344 /**
 345  * strlen_user: - Get the size of a string in user space.
 346  * @str: The string to measure.
 347  *
 348  * Context: User context only.  This function may sleep.
 349  *
 350  * Get the size of a NUL-terminated string in user space.
 351  *
 352  * Returns the size of the string INCLUDING the terminating NUL.
 353  * On exception, returns 0.
 354  *
 355  * If there is a limit on the length of a valid string, you may wish to
 356  * consider using strnlen_user() instead.
 357  */
 358 #define strlen_user(str) strnlen_user(str, ~0UL)
 359
 360 /*
 361  * Zero Userspace
 362  */
 363
 364 static inline unsigned long __must_check
 365 __clear_user(void __user *to, unsigned long n)
 366 {
 367         return uaccess.clear_user(n, to);
 368 }
 369
 370 static inline unsigned long __must_check
 371 clear_user(void __user *to, unsigned long n)
 372 {
 373         might_fault();
 374         if (access_ok(VERIFY_WRITE, to, n))
 375                 n = uaccess.clear_user(n, to);
 376         return n;
 377 }
 378
 379 extern int memcpy_real(void *, void *, size_t);
 380 extern void copy_to_absolute_zero(void *dest, void *src, size_t count);
 381 extern int copy_to_user_real(void __user *dest, void *src, size_t count);
 382 extern int copy_from_user_real(void *dest, void __user *src, size_t count);
 383
 384 #endif /* __S390_UACCESS_H */