linux/arch/alpha/include/asm/uaccess.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __ALPHA_UACCESS_H
   3#define __ALPHA_UACCESS_H
   4
   5/*
   6 * The fs value determines whether argument validity checking should be
   7 * performed or not.  If get_fs() == USER_DS, checking is performed, with
   8 * get_fs() == KERNEL_DS, checking is bypassed.
   9 *
  10 * Or at least it did once upon a time.  Nowadays it is a mask that
  11 * defines which bits of the address space are off limits.  This is a
  12 * wee bit faster than the above.
  13 *
  14 * For historical reasons, these macros are grossly misnamed.
  15 */
  16
  17#define KERNEL_DS       ((mm_segment_t) { 0UL })
  18#define USER_DS         ((mm_segment_t) { -0x40000000000UL })
  19
  20#define get_fs()  (current_thread_info()->addr_limit)
  21#define set_fs(x) (current_thread_info()->addr_limit = (x))
  22
  23#define segment_eq(a, b)        ((a).seg == (b).seg)
  24
  25/*
  26 * Is a address valid? This does a straightforward calculation rather
  27 * than tests.
  28 *
  29 * Address valid if:
  30 *  - "addr" doesn't have any high-bits set
  31 *  - AND "size" doesn't have any high-bits set
  32 *  - AND "addr+size-(size != 0)" doesn't have any high-bits set
  33 *  - OR we are in kernel mode.
  34 */
  35#define __access_ok(addr, size) ({                              \
  36        unsigned long __ao_a = (addr), __ao_b = (size);         \
  37        unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b;    \
  38        (get_fs().seg & (__ao_a | __ao_b | __ao_end)) == 0; })
  39
  40#define access_ok(addr, size)                           \
  41({                                                      \
  42        __chk_user_ptr(addr);                           \
  43        __access_ok(((unsigned long)(addr)), (size));   \
  44})
  45
  46/*
  47 * These are the main single-value transfer routines.  They automatically
  48 * use the right size if we just have the right pointer type.
  49 *
  50 * As the alpha uses the same address space for kernel and user
  51 * data, we can just do these as direct assignments.  (Of course, the
  52 * exception handling means that it's no longer "just"...)
  53 *
  54 * Careful to not
  55 * (a) re-use the arguments for side effects (sizeof/typeof is ok)
  56 * (b) require any knowledge of processes at this stage
  57 */
  58#define put_user(x, ptr) \
  59  __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  60#define get_user(x, ptr) \
  61  __get_user_check((x), (ptr), sizeof(*(ptr)))
  62
  63/*
  64 * The "__xxx" versions do not do address space checking, useful when
  65 * doing multiple accesses to the same area (the programmer has to do the
  66 * checks by hand with "access_ok()")
  67 */
  68#define __put_user(x, ptr) \
  69  __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
  70#define __get_user(x, ptr) \
  71  __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
  72  
  73/*
  74 * The "lda %1, 2b-1b(%0)" bits are magic to get the assembler to
  75 * encode the bits we need for resolving the exception.  See the
  76 * more extensive comments with fixup_inline_exception below for
  77 * more information.
  78 */
  79#define EXC(label,cont,res,err)                         \
  80        ".section __ex_table,\"a\"\n"                   \
  81        "       .long "#label"-.\n"                     \
  82        "       lda "#res","#cont"-"#label"("#err")\n"  \
  83        ".previous\n"
  84
  85extern void __get_user_unknown(void);
  86
  87#define __get_user_nocheck(x, ptr, size)                        \
  88({                                                              \
  89        long __gu_err = 0;                                      \
  90        unsigned long __gu_val;                                 \
  91        __chk_user_ptr(ptr);                                    \
  92        switch (size) {                                         \
  93          case 1: __get_user_8(ptr); break;                     \
  94          case 2: __get_user_16(ptr); break;                    \
  95          case 4: __get_user_32(ptr); break;                    \
  96          case 8: __get_user_64(ptr); break;                    \
  97          default: __get_user_unknown(); break;                 \
  98        }                                                       \
  99        (x) = (__force __typeof__(*(ptr))) __gu_val;            \
 100        __gu_err;                                               \
 101})
 102
 103#define __get_user_check(x, ptr, size)                          \
 104({                                                              \
 105        long __gu_err = -EFAULT;                                \
 106        unsigned long __gu_val = 0;                             \
 107        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
 108        if (__access_ok((unsigned long)__gu_addr, size)) {      \
 109                __gu_err = 0;                                   \
 110                switch (size) {                                 \
 111                  case 1: __get_user_8(__gu_addr); break;       \
 112                  case 2: __get_user_16(__gu_addr); break;      \
 113                  case 4: __get_user_32(__gu_addr); break;      \
 114                  case 8: __get_user_64(__gu_addr); break;      \
 115                  default: __get_user_unknown(); break;         \
 116                }                                               \
 117        }                                                       \
 118        (x) = (__force __typeof__(*(ptr))) __gu_val;            \
 119        __gu_err;                                               \
 120})
 121
 122struct __large_struct { unsigned long buf[100]; };
 123#define __m(x) (*(struct __large_struct __user *)(x))
 124
 125#define __get_user_64(addr)                             \
 126        __asm__("1: ldq %0,%2\n"                        \
 127        "2:\n"                                          \
 128        EXC(1b,2b,%0,%1)                                \
 129                : "=r"(__gu_val), "=r"(__gu_err)        \
 130                : "m"(__m(addr)), "1"(__gu_err))
 131
 132#define __get_user_32(addr)                             \
 133        __asm__("1: ldl %0,%2\n"                        \
 134        "2:\n"                                          \
 135        EXC(1b,2b,%0,%1)                                \
 136                : "=r"(__gu_val), "=r"(__gu_err)        \
 137                : "m"(__m(addr)), "1"(__gu_err))
 138
 139#ifdef __alpha_bwx__
 140/* Those lucky bastards with ev56 and later CPUs can do byte/word moves.  */
 141
 142#define __get_user_16(addr)                             \
 143        __asm__("1: ldwu %0,%2\n"                       \
 144        "2:\n"                                          \
 145        EXC(1b,2b,%0,%1)                                \
 146                : "=r"(__gu_val), "=r"(__gu_err)        \
 147                : "m"(__m(addr)), "1"(__gu_err))
 148
 149#define __get_user_8(addr)                              \
 150        __asm__("1: ldbu %0,%2\n"                       \
 151        "2:\n"                                          \
 152        EXC(1b,2b,%0,%1)                                \
 153                : "=r"(__gu_val), "=r"(__gu_err)        \
 154                : "m"(__m(addr)), "1"(__gu_err))
 155#else
 156/* Unfortunately, we can't get an unaligned access trap for the sub-word
 157   load, so we have to do a general unaligned operation.  */
 158
 159#define __get_user_16(addr)                                             \
 160{                                                                       \
 161        long __gu_tmp;                                                  \
 162        __asm__("1: ldq_u %0,0(%3)\n"                                   \
 163        "2:     ldq_u %1,1(%3)\n"                                       \
 164        "       extwl %0,%3,%0\n"                                       \
 165        "       extwh %1,%3,%1\n"                                       \
 166        "       or %0,%1,%0\n"                                          \
 167        "3:\n"                                                          \
 168        EXC(1b,3b,%0,%2)                                                \
 169        EXC(2b,3b,%0,%2)                                                \
 170                : "=&r"(__gu_val), "=&r"(__gu_tmp), "=r"(__gu_err)      \
 171                : "r"(addr), "2"(__gu_err));                            \
 172}
 173
 174#define __get_user_8(addr)                                              \
 175        __asm__("1: ldq_u %0,0(%2)\n"                                   \
 176        "       extbl %0,%2,%0\n"                                       \
 177        "2:\n"                                                          \
 178        EXC(1b,2b,%0,%1)                                                \
 179                : "=&r"(__gu_val), "=r"(__gu_err)                       \
 180                : "r"(addr), "1"(__gu_err))
 181#endif
 182
 183extern void __put_user_unknown(void);
 184
 185#define __put_user_nocheck(x, ptr, size)                        \
 186({                                                              \
 187        long __pu_err = 0;                                      \
 188        __chk_user_ptr(ptr);                                    \
 189        switch (size) {                                         \
 190          case 1: __put_user_8(x, ptr); break;                  \
 191          case 2: __put_user_16(x, ptr); break;                 \
 192          case 4: __put_user_32(x, ptr); break;                 \
 193          case 8: __put_user_64(x, ptr); break;                 \
 194          default: __put_user_unknown(); break;                 \
 195        }                                                       \
 196        __pu_err;                                               \
 197})
 198
 199#define __put_user_check(x, ptr, size)                          \
 200({                                                              \
 201        long __pu_err = -EFAULT;                                \
 202        __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
 203        if (__access_ok((unsigned long)__pu_addr, size)) {      \
 204                __pu_err = 0;                                   \
 205                switch (size) {                                 \
 206                  case 1: __put_user_8(x, __pu_addr); break;    \
 207                  case 2: __put_user_16(x, __pu_addr); break;   \
 208                  case 4: __put_user_32(x, __pu_addr); break;   \
 209                  case 8: __put_user_64(x, __pu_addr); break;   \
 210                  default: __put_user_unknown(); break;         \
 211                }                                               \
 212        }                                                       \
 213        __pu_err;                                               \
 214})
 215
 216/*
 217 * The "__put_user_xx()" macros tell gcc they read from memory
 218 * instead of writing: this is because they do not write to
 219 * any memory gcc knows about, so there are no aliasing issues
 220 */
 221#define __put_user_64(x, addr)                                  \
 222__asm__ __volatile__("1: stq %r2,%1\n"                          \
 223        "2:\n"                                                  \
 224        EXC(1b,2b,$31,%0)                                       \
 225                : "=r"(__pu_err)                                \
 226                : "m" (__m(addr)), "rJ" (x), "0"(__pu_err))
 227
 228#define __put_user_32(x, addr)                                  \
 229__asm__ __volatile__("1: stl %r2,%1\n"                          \
 230        "2:\n"                                                  \
 231        EXC(1b,2b,$31,%0)                                       \
 232                : "=r"(__pu_err)                                \
 233                : "m"(__m(addr)), "rJ"(x), "0"(__pu_err))
 234
 235#ifdef __alpha_bwx__
 236/* Those lucky bastards with ev56 and later CPUs can do byte/word moves.  */
 237
 238#define __put_user_16(x, addr)                                  \
 239__asm__ __volatile__("1: stw %r2,%1\n"                          \
 240        "2:\n"                                                  \
 241        EXC(1b,2b,$31,%0)                                       \
 242                : "=r"(__pu_err)                                \
 243                : "m"(__m(addr)), "rJ"(x), "0"(__pu_err))
 244
 245#define __put_user_8(x, addr)                                   \
 246__asm__ __volatile__("1: stb %r2,%1\n"                          \
 247        "2:\n"                                                  \
 248        EXC(1b,2b,$31,%0)                                       \
 249                : "=r"(__pu_err)                                \
 250                : "m"(__m(addr)), "rJ"(x), "0"(__pu_err))
 251#else
 252/* Unfortunately, we can't get an unaligned access trap for the sub-word
 253   write, so we have to do a general unaligned operation.  */
 254
 255#define __put_user_16(x, addr)                                  \
 256{                                                               \
 257        long __pu_tmp1, __pu_tmp2, __pu_tmp3, __pu_tmp4;        \
 258        __asm__ __volatile__(                                   \
 259        "1:     ldq_u %2,1(%5)\n"                               \
 260        "2:     ldq_u %1,0(%5)\n"                               \
 261        "       inswh %6,%5,%4\n"                               \
 262        "       inswl %6,%5,%3\n"                               \
 263        "       mskwh %2,%5,%2\n"                               \
 264        "       mskwl %1,%5,%1\n"                               \
 265        "       or %2,%4,%2\n"                                  \
 266        "       or %1,%3,%1\n"                                  \
 267        "3:     stq_u %2,1(%5)\n"                               \
 268        "4:     stq_u %1,0(%5)\n"                               \
 269        "5:\n"                                                  \
 270        EXC(1b,5b,$31,%0)                                       \
 271        EXC(2b,5b,$31,%0)                                       \
 272        EXC(3b,5b,$31,%0)                                       \
 273        EXC(4b,5b,$31,%0)                                       \
 274                : "=r"(__pu_err), "=&r"(__pu_tmp1),             \
 275                  "=&r"(__pu_tmp2), "=&r"(__pu_tmp3),           \
 276                  "=&r"(__pu_tmp4)                              \
 277                : "r"(addr), "r"((unsigned long)(x)), "0"(__pu_err)); \
 278}
 279
 280#define __put_user_8(x, addr)                                   \
 281{                                                               \
 282        long __pu_tmp1, __pu_tmp2;                              \
 283        __asm__ __volatile__(                                   \
 284        "1:     ldq_u %1,0(%4)\n"                               \
 285        "       insbl %3,%4,%2\n"                               \
 286        "       mskbl %1,%4,%1\n"                               \
 287        "       or %1,%2,%1\n"                                  \
 288        "2:     stq_u %1,0(%4)\n"                               \
 289        "3:\n"                                                  \
 290        EXC(1b,3b,$31,%0)                                       \
 291        EXC(2b,3b,$31,%0)                                       \
 292                : "=r"(__pu_err),                               \
 293                  "=&r"(__pu_tmp1), "=&r"(__pu_tmp2)            \
 294                : "r"((unsigned long)(x)), "r"(addr), "0"(__pu_err)); \
 295}
 296#endif
 297
 298
 299/*
 300 * Complex access routines
 301 */
 302
 303extern long __copy_user(void *to, const void *from, long len);
 304
 305static inline unsigned long
 306raw_copy_from_user(void *to, const void __user *from, unsigned long len)
 307{
 308        return __copy_user(to, (__force const void *)from, len);
 309}
 310
 311static inline unsigned long
 312raw_copy_to_user(void __user *to, const void *from, unsigned long len)
 313{
 314        return __copy_user((__force void *)to, from, len);
 315}
 316
 317extern long __clear_user(void __user *to, long len);
 318
 319extern inline long
 320clear_user(void __user *to, long len)
 321{
 322        if (__access_ok((unsigned long)to, len))
 323                len = __clear_user(to, len);
 324        return len;
 325}
 326
 327#define user_addr_max() \
 328        (uaccess_kernel() ? ~0UL : TASK_SIZE)
 329
 330extern long strncpy_from_user(char *dest, const char __user *src, long count);
 331extern __must_check long strnlen_user(const char __user *str, long n);
 332
 333#include <asm/extable.h>
 334
 335#endif /* __ALPHA_UACCESS_H */
 336