arch/s390/include/asm/uaccess.h

   1 /*
   2  *  S390 version
   3  *    Copyright IBM Corp. 1999, 2000
   4  *    Author(s): Hartmut Penner (hp@de.ibm.com),
   5  *               Martin Schwidefsky (schwidefsky@de.ibm.com)
   6  *
   7  *  Derived from "include/asm-i386/uaccess.h"
   8  */
   9 #ifndef __S390_UACCESS_H
  10 #define __S390_UACCESS_H
  11
  12 /*
  13  * User space memory access functions
  14  */
  15 #include <linux/sched.h>
  16 #include <linux/errno.h>
  17 #include <asm/ctl_reg.h>
  18
  19 #define VERIFY_READ     0
  20 #define VERIFY_WRITE    1
  21
  22
  23 /*
  24  * The fs value determines whether argument validity checking should be
  25  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  26  * get_fs() == KERNEL_DS, checking is bypassed.
  27  *
  28  * For historical reasons, these macros are grossly misnamed.
  29  */
  30
  31 #define MAKE_MM_SEG(a)  ((mm_segment_t) { (a) })
  32
  33
  34 #define KERNEL_DS       MAKE_MM_SEG(0)
  35 #define USER_DS         MAKE_MM_SEG(1)
  36
  37 #define get_ds()        (KERNEL_DS)
  38 #define get_fs()        (current->thread.mm_segment)
  39
  40 #define set_fs(x) \
  41 ({                                                                      \
  42         unsigned long __pto;                                            \
  43         current->thread.mm_segment = (x);                               \
  44         __pto = current->thread.mm_segment.ar4 ?                        \
  45                 S390_lowcore.user_asce : S390_lowcore.kernel_asce;      \
  46         __ctl_load(__pto, 7, 7);                                        \
  47 })
  48
  49 #define segment_eq(a,b) ((a).ar4 == (b).ar4)
  50
  51 static inline int __range_ok(unsigned long addr, unsigned long size)
  52 {
  53         return 1;
  54 }
  55
  56 #define __access_ok(addr, size)                         \
  57 ({                                                      \
  58         __chk_user_ptr(addr);                           \
  59         __range_ok((unsigned long)(addr), (size));      \
  60 })
  61
  62 #define access_ok(type, addr, size) __access_ok(addr, size)
  63
  64 /*
  65  * The exception table consists of pairs of addresses: the first is the
  66  * address of an instruction that is allowed to fault, and the second is
  67  * the address at which the program should continue.  No registers are
  68  * modified, so it is entirely up to the continuation code to figure out
  69  * what to do.
  70  *
  71  * All the routines below use bits of fixup code that are out of line
  72  * with the main instruction path.  This means when everything is well,
  73  * we don't even have to jump over them.  Further, they do not intrude
  74  * on our cache or tlb entries.
  75  */
  76
  77 struct exception_table_entry
  78 {
  79         int insn, fixup;
  80 };
  81
  82 static inline unsigned long extable_insn(const struct exception_table_entry *x)
  83 {
  84         return (unsigned long)&x->insn + x->insn;
  85 }
  86
  87 static inline unsigned long extable_fixup(const struct exception_table_entry *x)
  88 {
  89         return (unsigned long)&x->fixup + x->fixup;
  90 }
  91
  92 #define ARCH_HAS_SORT_EXTABLE
  93 #define ARCH_HAS_SEARCH_EXTABLE
  94
  95 struct uaccess_ops {
  96         size_t (*copy_from_user)(size_t, const void __user *, void *);
  97         size_t (*copy_from_user_small)(size_t, const void __user *, void *);
  98         size_t (*copy_to_user)(size_t, void __user *, const void *);
  99         size_t (*copy_to_user_small)(size_t, void __user *, const void *);
 100         size_t (*copy_in_user)(size_t, void __user *, const void __user *);
 101         size_t (*clear_user)(size_t, void __user *);
 102         size_t (*strnlen_user)(size_t, const char __user *);
 103         size_t (*strncpy_from_user)(size_t, const char __user *, char *);
 104         int (*futex_atomic_op)(int op, u32 __user *, int oparg, int *old);
 105         int (*futex_atomic_cmpxchg)(u32 *, u32 __user *, u32 old, u32 new);
 106 };
 107
 108 extern struct uaccess_ops uaccess;
 109 extern struct uaccess_ops uaccess_std;
 110 extern struct uaccess_ops uaccess_mvcos;
 111 extern struct uaccess_ops uaccess_mvcos_switch;
 112 extern struct uaccess_ops uaccess_pt;
 113
 114 extern int __handle_fault(unsigned long, unsigned long, int);
 115
 116 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 117 {
 118         size = uaccess.copy_to_user_small(size, ptr, x);
 119         return size ? -EFAULT : size;
 120 }
 121
 122 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 123 {
 124         size = uaccess.copy_from_user_small(size, ptr, x);
 125         return size ? -EFAULT : size;
 126 }
 127
 128 /*
 129  * These are the main single-value transfer routines.  They automatically
 130  * use the right size if we just have the right pointer type.
 131  */
 132 #define __put_user(x, ptr) \
 133 ({                                                              \
 134         __typeof__(*(ptr)) __x = (x);                           \
 135         int __pu_err = -EFAULT;                                 \
 136         __chk_user_ptr(ptr);                                    \
 137         switch (sizeof (*(ptr))) {                              \
 138         case 1:                                                 \
 139         case 2:                                                 \
 140         case 4:                                                 \
 141         case 8:                                                 \
 142                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 143                                          ptr, &__x);            \
 144                 break;                                          \
 145         default:                                                \
 146                 __put_user_bad();                               \
 147                 break;                                          \
 148          }                                                      \
 149         __pu_err;                                               \
 150 })
 151
 152 #define put_user(x, ptr)                                        \
 153 ({                                                              \
 154         might_fault();                                          \
 155         __put_user(x, ptr);                                     \
 156 })
 157
 158
 159 extern int __put_user_bad(void) __attribute__((noreturn));
 160
 161 #define __get_user(x, ptr)                                      \
 162 ({                                                              \
 163         int __gu_err = -EFAULT;                                 \
 164         __chk_user_ptr(ptr);                                    \
 165         switch (sizeof(*(ptr))) {                               \
 166         case 1: {                                               \
 167                 unsigned char __x = 0;                          \
 168                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 169                                          ptr, &__x);            \
 170                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 171                 break;                                          \
 172         };                                                      \
 173         case 2: {                                               \
 174                 unsigned short __x = 0;                         \
 175                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 176                                          ptr, &__x);            \
 177                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 178                 break;                                          \
 179         };                                                      \
 180         case 4: {                                               \
 181                 unsigned int __x = 0;                           \
 182                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 183                                          ptr, &__x);            \
 184                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 185                 break;                                          \
 186         };                                                      \
 187         case 8: {                                               \
 188                 unsigned long long __x = 0;                     \
 189                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 190                                          ptr, &__x);            \
 191                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 192                 break;                                          \
 193         };                                                      \
 194         default:                                                \
 195                 __get_user_bad();                               \
 196                 break;                                          \
 197         }                                                       \
 198         __gu_err;                                               \
 199 })
 200
 201 #define get_user(x, ptr)                                        \
 202 ({                                                              \
 203         might_fault();                                          \
 204         __get_user(x, ptr);                                     \
 205 })
 206
 207 extern int __get_user_bad(void) __attribute__((noreturn));
 208
 209 #define __put_user_unaligned __put_user
 210 #define __get_user_unaligned __get_user
 211
 212 /**
 213  * __copy_to_user: - Copy a block of data into user space, with less checking.
 214  * @to:   Destination address, in user space.
 215  * @from: Source address, in kernel space.
 216  * @n:    Number of bytes to copy.
 217  *
 218  * Context: User context only.  This function may sleep.
 219  *
 220  * Copy data from kernel space to user space.  Caller must check
 221  * the specified block with access_ok() before calling this function.
 222  *
 223  * Returns number of bytes that could not be copied.
 224  * On success, this will be zero.
 225  */
 226 static inline unsigned long __must_check
 227 __copy_to_user(void __user *to, const void *from, unsigned long n)
 228 {
 229         if (__builtin_constant_p(n) && (n <= 256))
 230                 return uaccess.copy_to_user_small(n, to, from);
 231         else
 232                 return uaccess.copy_to_user(n, to, from);
 233 }
 234
 235 #define __copy_to_user_inatomic __copy_to_user
 236 #define __copy_from_user_inatomic __copy_from_user
 237
 238 /**
 239  * copy_to_user: - Copy a block of data into user space.
 240  * @to:   Destination address, in user space.
 241  * @from: Source address, in kernel space.
 242  * @n:    Number of bytes to copy.
 243  *
 244  * Context: User context only.  This function may sleep.
 245  *
 246  * Copy data from kernel space to user space.
 247  *
 248  * Returns number of bytes that could not be copied.
 249  * On success, this will be zero.
 250  */
 251 static inline unsigned long __must_check
 252 copy_to_user(void __user *to, const void *from, unsigned long n)
 253 {
 254         might_fault();
 255         return __copy_to_user(to, from, n);
 256 }
 257
 258 /**
 259  * __copy_from_user: - Copy a block of data from user space, with less checking.
 260  * @to:   Destination address, in kernel space.
 261  * @from: Source address, in user space.
 262  * @n:    Number of bytes to copy.
 263  *
 264  * Context: User context only.  This function may sleep.
 265  *
 266  * Copy data from user space to kernel space.  Caller must check
 267  * the specified block with access_ok() before calling this function.
 268  *
 269  * Returns number of bytes that could not be copied.
 270  * On success, this will be zero.
 271  *
 272  * If some data could not be copied, this function will pad the copied
 273  * data to the requested size using zero bytes.
 274  */
 275 static inline unsigned long __must_check
 276 __copy_from_user(void *to, const void __user *from, unsigned long n)
 277 {
 278         if (__builtin_constant_p(n) && (n <= 256))
 279                 return uaccess.copy_from_user_small(n, from, to);
 280         else
 281                 return uaccess.copy_from_user(n, from, to);
 282 }
 283
 284 extern void copy_from_user_overflow(void)
 285 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 286 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 287 #endif
 288 ;
 289
 290 /**
 291  * copy_from_user: - Copy a block of data from user space.
 292  * @to:   Destination address, in kernel space.
 293  * @from: Source address, in user space.
 294  * @n:    Number of bytes to copy.
 295  *
 296  * Context: User context only.  This function may sleep.
 297  *
 298  * Copy data from user space to kernel space.
 299  *
 300  * Returns number of bytes that could not be copied.
 301  * On success, this will be zero.
 302  *
 303  * If some data could not be copied, this function will pad the copied
 304  * data to the requested size using zero bytes.
 305  */
 306 static inline unsigned long __must_check
 307 copy_from_user(void *to, const void __user *from, unsigned long n)
 308 {
 309         unsigned int sz = __compiletime_object_size(to);
 310
 311         might_fault();
 312         if (unlikely(sz != -1 && sz < n)) {
 313                 copy_from_user_overflow();
 314                 return n;
 315         }
 316         return __copy_from_user(to, from, n);
 317 }
 318
 319 static inline unsigned long __must_check
 320 __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 321 {
 322         return uaccess.copy_in_user(n, to, from);
 323 }
 324
 325 static inline unsigned long __must_check
 326 copy_in_user(void __user *to, const void __user *from, unsigned long n)
 327 {
 328         might_fault();
 329         return __copy_in_user(to, from, n);
 330 }
 331
 332 /*
 333  * Copy a null terminated string from userspace.
 334  */
 335 static inline long __must_check
 336 strncpy_from_user(char *dst, const char __user *src, long count)
 337 {
 338         might_fault();
 339         return uaccess.strncpy_from_user(count, src, dst);
 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         return uaccess.clear_user(n, to);
 380 }
 381
 382 extern int copy_to_user_real(void __user *dest, void *src, size_t count);
 383 extern int copy_from_user_real(void *dest, void __user *src, size_t count);
 384
 385 #endif /* __S390_UACCESS_H */