include/asm-ppc64/uaccess.h

   1 #ifndef _PPC64_UACCESS_H
   2 #define _PPC64_UACCESS_H
   3
   4 /*
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version
   8  * 2 of the License, or (at your option) any later version.
   9  */
  10
  11 #ifndef __ASSEMBLY__
  12 #include <linux/sched.h>
  13 #include <linux/errno.h>
  14 #include <asm/pgtable.h>
  15 #include <asm/processor.h>
  16
  17 #define VERIFY_READ     0
  18 #define VERIFY_WRITE    1
  19
  20 /*
  21  * The fs value determines whether argument validity checking should be
  22  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  23  * get_fs() == KERNEL_DS, checking is bypassed.
  24  *
  25  * For historical reasons, these macros are grossly misnamed.
  26  */
  27
  28 #define KERNEL_DS       ((mm_segment_t) { 0 })
  29 #define USER_DS         ((mm_segment_t) { 1 })
  30
  31 #define get_ds()        (KERNEL_DS)
  32 #define get_fs()        (current->thread.fs)
  33 #define set_fs(val)     (current->thread.fs = (val))
  34
  35 #define segment_eq(a,b) ((a).seg == (b).seg)
  36
  37 #define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
  38 #define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
  39 #define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size)))
  40 #define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size))
  41
  42 static inline int verify_area(int type, const void * addr, unsigned long size)
  43 {
  44         return access_ok(type,addr,size) ? 0 : -EFAULT;
  45 }
  46
  47
  48 /*
  49  * The exception table consists of pairs of addresses: the first is the
  50  * address of an instruction that is allowed to fault, and the second is
  51  * the address at which the program should continue.  No registers are
  52  * modified, so it is entirely up to the continuation code to figure out
  53  * what to do.
  54  *
  55  * All the routines below use bits of fixup code that are out of line
  56  * with the main instruction path.  This means when everything is well,
  57  * we don't even have to jump over them.  Further, they do not intrude
  58  * on our cache or tlb entries.
  59  */
  60
  61 struct exception_table_entry
  62 {
  63         unsigned long insn, fixup;
  64 };
  65
  66 /* Returns 0 if exception not found and fixup otherwise.  */
  67 extern unsigned long search_exception_table(unsigned long);
  68 extern void sort_exception_table(void);
  69
  70 /*
  71  * These are the main single-value transfer routines.  They automatically
  72  * use the right size if we just have the right pointer type.
  73  *
  74  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  75  * and yet we don't want to do any pointers, because that is too much
  76  * of a performance impact. Thus we have a few rather ugly macros here,
  77  * and hide all the uglyness from the user.
  78  *
  79  * The "__xxx" versions of the user access functions are versions that
  80  * do not verify the address space, that must have been done previously
  81  * with a separate "access_ok()" call (this is used when we do multiple
  82  * accesses to the same area of user memory).
  83  *
  84  * As we use the same address space for kernel and user data on the
  85  * PowerPC, we can just do these as direct assignments.  (Of course, the
  86  * exception handling means that it's no longer "just"...)
  87  */
  88 #define get_user(x,ptr) \
  89   __get_user_check((x),(ptr),sizeof(*(ptr)))
  90 #define put_user(x,ptr) \
  91   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
  92
  93 #define __get_user(x,ptr) \
  94   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
  95 #define __put_user(x,ptr) \
  96   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
  97
  98 extern long __put_user_bad(void);
  99
 100 #define __put_user_nocheck(x,ptr,size)                  \
 101 ({                                                      \
 102         long __pu_err;                                  \
 103         __put_user_size((x),(ptr),(size),__pu_err);     \
 104         __pu_err;                                       \
 105 })
 106
 107 #define __put_user_check(x,ptr,size)                            \
 108 ({                                                              \
 109         long __pu_err = -EFAULT;                                \
 110         __typeof__(*(ptr)) *__pu_addr = (ptr);                  \
 111         if (access_ok(VERIFY_WRITE,__pu_addr,size))             \
 112                 __put_user_size((x),__pu_addr,(size),__pu_err); \
 113         __pu_err;                                               \
 114 })
 115
 116 #define __put_user_size(x,ptr,size,retval)                      \
 117 do {                                                            \
 118         retval = 0;                                             \
 119         switch (size) {                                         \
 120           case 1: __put_user_asm(x,ptr,retval,"stb"); break;    \
 121           case 2: __put_user_asm(x,ptr,retval,"sth"); break;    \
 122           case 4: __put_user_asm(x,ptr,retval,"stw"); break;    \
 123           case 8: __put_user_asm(x,ptr,retval,"std"); break;    \
 124           default: __put_user_bad();                            \
 125         }                                                       \
 126 } while (0)
 127
 128 /*
 129  * We don't tell gcc that we are accessing memory, but this is OK
 130  * because we do not write to any memory gcc knows about, so there
 131  * are no aliasing issues.
 132  */
 133 #define __put_user_asm(x, addr, err, op)                        \
 134         __asm__ __volatile__(                                   \
 135                 "1:     "op" %1,0(%2)\n"                        \
 136                 "2:\n"                                          \
 137                 ".section .fixup,\"ax\"\n"                      \
 138                 "3:     li %0,%3\n"                             \
 139                 "       b 2b\n"                                 \
 140                 ".previous\n"                                   \
 141                 ".section __ex_table,\"a\"\n"                   \
 142                 "       .align 3\n"                             \
 143                 "       .llong 1b,3b\n"                         \
 144                 ".previous"                                     \
 145                 : "=r"(err)                                     \
 146                 : "r"(x), "b"(addr), "i"(-EFAULT), "0"(err))
 147
 148
 149 #define __get_user_nocheck(x,ptr,size)                          \
 150 ({                                                              \
 151         long __gu_err, __gu_val;                                \
 152         __get_user_size(__gu_val,(ptr),(size),__gu_err);        \
 153         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 154         __gu_err;                                               \
 155 })
 156
 157 #define __get_user_check(x,ptr,size)                                    \
 158 ({                                                                      \
 159         long __gu_err = -EFAULT, __gu_val = 0;                          \
 160         const __typeof__(*(ptr)) *__gu_addr = (ptr);                    \
 161         if (access_ok(VERIFY_READ,__gu_addr,size))                      \
 162                 __get_user_size(__gu_val,__gu_addr,(size),__gu_err);    \
 163         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 164         __gu_err;                                                       \
 165 })
 166
 167 extern long __get_user_bad(void);
 168
 169 #define __get_user_size(x,ptr,size,retval)                      \
 170 do {                                                            \
 171         retval = 0;                                             \
 172         switch (size) {                                         \
 173           case 1: __get_user_asm(x,ptr,retval,"lbz"); break;    \
 174           case 2: __get_user_asm(x,ptr,retval,"lhz"); break;    \
 175           case 4: __get_user_asm(x,ptr,retval,"lwz"); break;    \
 176           case 8: __get_user_asm(x,ptr,retval,"ld");  break;    \
 177           default: (x) = __get_user_bad();                      \
 178         }                                                       \
 179 } while (0)
 180
 181 #define __get_user_asm(x, addr, err, op)                \
 182         __asm__ __volatile__(                           \
 183                 "1:     "op" %1,0(%2)\n"                \
 184                 "2:\n"                                  \
 185                 ".section .fixup,\"ax\"\n"              \
 186                 "3:     li %0,%3\n"                     \
 187                 "       li %1,0\n"                      \
 188                 "       b 2b\n"                         \
 189                 ".previous\n"                           \
 190                 ".section __ex_table,\"a\"\n"           \
 191                 "       .align 3\n"                     \
 192                 "       .llong 1b,3b\n"                 \
 193                 ".previous"                             \
 194                 : "=r"(err), "=r"(x)                    \
 195                 : "b"(addr), "i"(-EFAULT), "0"(err))
 196
 197 /* more complex routines */
 198
 199 extern unsigned long __copy_tofrom_user(void *to, const void *from, unsigned long size);
 200
 201 static inline unsigned long
 202 copy_from_user(void *to, const void *from, unsigned long n)
 203 {
 204         unsigned long over;
 205
 206         if (access_ok(VERIFY_READ, from, n))
 207                 return __copy_tofrom_user(to, from, n);
 208         if ((unsigned long)from < TASK_SIZE) {
 209                 over = (unsigned long)from + n - TASK_SIZE;
 210                 return __copy_tofrom_user(to, from, n - over) + over;
 211         }
 212         return n;
 213 }
 214
 215 static inline unsigned long
 216 copy_to_user(void *to, const void *from, unsigned long n)
 217 {
 218         unsigned long over;
 219
 220         if (access_ok(VERIFY_WRITE, to, n))
 221                 return __copy_tofrom_user(to, from, n);
 222         if ((unsigned long)to < TASK_SIZE) {
 223                 over = (unsigned long)to + n - TASK_SIZE;
 224                 return __copy_tofrom_user(to, from, n - over) + over;
 225         }
 226         return n;
 227 }
 228
 229 #define __copy_from_user(to, from, size) \
 230         __copy_tofrom_user((to), (from), (size))
 231 #define __copy_to_user(to, from, size) \
 232         __copy_tofrom_user((to), (from), (size))
 233
 234 extern unsigned long __clear_user(void *addr, unsigned long size);
 235
 236 static inline unsigned long
 237 clear_user(void *addr, unsigned long size)
 238 {
 239         if (access_ok(VERIFY_WRITE, addr, size))
 240                 return __clear_user(addr, size);
 241         if ((unsigned long)addr < TASK_SIZE) {
 242                 unsigned long over = (unsigned long)addr + size - TASK_SIZE;
 243                 return __clear_user(addr, size - over) + over;
 244         }
 245         return size;
 246 }
 247
 248 extern int __strncpy_from_user(char *dst, const char *src, long count);
 249
 250 static inline long
 251 strncpy_from_user(char *dst, const char *src, long count)
 252 {
 253         if (access_ok(VERIFY_READ, src, 1))
 254                 return __strncpy_from_user(dst, src, count);
 255         return -EFAULT;
 256 }
 257
 258 /*
 259  * Return the size of a string (including the ending 0)
 260  *
 261  * Return 0 for error
 262  */
 263
 264 extern int __strnlen_user(const char *str, long len, unsigned long top);
 265
 266 /*
 267  * Returns the length of the string at str (including the null byte),
 268  * or 0 if we hit a page we can't access,
 269  * or something > len if we didn't find a null byte.
 270  *
 271  * The `top' parameter to __strnlen_user is to make sure that
 272  * we can never overflow from the user area into kernel space.
 273  */
 274 static inline int strnlen_user(const char *str, long len)
 275 {
 276         unsigned long top = __kernel_ok? ~0UL: TASK_SIZE - 1;
 277
 278         if ((unsigned long)str > top)
 279                 return 0;
 280         return __strnlen_user(str, len, top);
 281 }
 282
 283 #define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
 284
 285 #endif  /* __ASSEMBLY__ */
 286
 287 #endif  /* _PPC64_UACCESS_H */