linux-old/include/asm-ppc64/uaccess.h
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   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
  42static 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
  61struct exception_table_entry
  62{
  63        unsigned long insn, fixup;
  64};
  65
  66/* Returns 0 if exception not found and fixup otherwise.  */
  67extern unsigned long search_exception_table(unsigned long);
  68extern 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
  98extern 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)                      \
 117do {                                                            \
 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
 167extern long __get_user_bad(void);
 168
 169#define __get_user_size(x,ptr,size,retval)                      \
 170do {                                                            \
 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
 199extern unsigned long __copy_tofrom_user(void *to, const void *from, unsigned long size);
 200
 201static inline unsigned long
 202copy_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
 215static inline unsigned long
 216copy_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
 234extern unsigned long __clear_user(void *addr, unsigned long size);
 235
 236static inline unsigned long
 237clear_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
 248extern int __strncpy_from_user(char *dst, const char *src, long count);
 249
 250static inline long
 251strncpy_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
 264extern 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 */
 274static 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 */
 288
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