include/asm-ia64/uaccess.h

   1 #ifndef _ASM_IA64_UACCESS_H
   2 #define _ASM_IA64_UACCESS_H
   3
   4 /*
   5  * This file defines various macros to transfer memory areas across
   6  * the user/kernel boundary.  This needs to be done carefully because
   7  * this code is executed in kernel mode and uses user-specified
   8  * addresses.  Thus, we need to be careful not to let the user to
   9  * trick us into accessing kernel memory that would normally be
  10  * inaccessible.  This code is also fairly performance sensitive,
  11  * so we want to spend as little time doing safety checks as
  12  * possible.
  13  *
  14  * To make matters a bit more interesting, these macros sometimes also
  15  * called from within the kernel itself, in which case the address
  16  * validity check must be skipped.  The get_fs() macro tells us what
  17  * to do: if get_fs()==USER_DS, checking is performed, if
  18  * get_fs()==KERNEL_DS, checking is bypassed.
  19  *
  20  * Note that even if the memory area specified by the user is in a
  21  * valid address range, it is still possible that we'll get a page
  22  * fault while accessing it.  This is handled by filling out an
  23  * exception handler fixup entry for each instruction that has the
  24  * potential to fault.  When such a fault occurs, the page fault
  25  * handler checks to see whether the faulting instruction has a fixup
  26  * associated and, if so, sets r8 to -EFAULT and clears r9 to 0 and
  27  * then resumes execution at the continuation point.
  28  *
  29  * Based on <asm-alpha/uaccess.h>.
  30  *
  31  * Copyright (C) 1998, 1999, 2001-2004 Hewlett-Packard Co
  32  *      David Mosberger-Tang <davidm@hpl.hp.com>
  33  */
  34
  35 #include <linux/compiler.h>
  36 #include <linux/errno.h>
  37 #include <linux/sched.h>
  38
  39 #include <asm/intrinsics.h>
  40 #include <asm/pgtable.h>
  41
  42 /*
  43  * For historical reasons, the following macros are grossly misnamed:
  44  */
  45 #define KERNEL_DS       ((mm_segment_t) { ~0UL })               /* cf. access_ok() */
  46 #define USER_DS         ((mm_segment_t) { TASK_SIZE-1 })        /* cf. access_ok() */
  47
  48 #define VERIFY_READ     0
  49 #define VERIFY_WRITE    1
  50
  51 #define get_ds()  (KERNEL_DS)
  52 #define get_fs()  (current_thread_info()->addr_limit)
  53 #define set_fs(x) (current_thread_info()->addr_limit = (x))
  54
  55 #define segment_eq(a, b)        ((a).seg == (b).seg)
  56
  57 /*
  58  * When accessing user memory, we need to make sure the entire area really is in
  59  * user-level space.  In order to do this efficiently, we make sure that the page at
  60  * address TASK_SIZE is never valid.  We also need to make sure that the address doesn't
  61  * point inside the virtually mapped linear page table.
  62  */
  63 #define __access_ok(addr, size, segment)                                                \
  64 ({                                                                                      \
  65         __chk_user_ptr(addr);                                                           \
  66         (likely((unsigned long) (addr) <= (segment).seg)                                \
  67          && ((segment).seg == KERNEL_DS.seg                                             \
  68              || likely(REGION_OFFSET((unsigned long) (addr)) < RGN_MAP_LIMIT)));        \
  69 })
  70 #define access_ok(type, addr, size)     __access_ok((addr), (size), get_fs())
  71
  72 static inline int
  73 verify_area (int type, const void __user *addr, unsigned long size)
  74 {
  75         return access_ok(type, addr, size) ? 0 : -EFAULT;
  76 }
  77
  78 /*
  79  * These are the main single-value transfer routines.  They automatically
  80  * use the right size if we just have the right pointer type.
  81  *
  82  * Careful to not
  83  * (a) re-use the arguments for side effects (sizeof/typeof is ok)
  84  * (b) require any knowledge of processes at this stage
  85  */
  86 #define put_user(x, ptr)        __put_user_check((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)), get_fs())
  87 #define get_user(x, ptr)        __get_user_check((x), (ptr), sizeof(*(ptr)), get_fs())
  88
  89 /*
  90  * The "__xxx" versions do not do address space checking, useful when
  91  * doing multiple accesses to the same area (the programmer has to do the
  92  * checks by hand with "access_ok()")
  93  */
  94 #define __put_user(x, ptr)      __put_user_nocheck((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
  95 #define __get_user(x, ptr)      __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
  96
  97 extern long __put_user_unaligned_unknown (void);
  98
  99 #define __put_user_unaligned(x, ptr)                                                            \
 100 ({                                                                                              \
 101         long __ret;                                                                             \
 102         switch (sizeof(*(ptr))) {                                                               \
 103                 case 1: __ret = __put_user((x), (ptr)); break;                                  \
 104                 case 2: __ret = (__put_user((x), (u8 __user *)(ptr)))                           \
 105                         | (__put_user((x) >> 8, ((u8 __user *)(ptr) + 1))); break;              \
 106                 case 4: __ret = (__put_user((x), (u16 __user *)(ptr)))                          \
 107                         | (__put_user((x) >> 16, ((u16 __user *)(ptr) + 1))); break;            \
 108                 case 8: __ret = (__put_user((x), (u32 __user *)(ptr)))                          \
 109                         | (__put_user((x) >> 32, ((u32 __user *)(ptr) + 1))); break;            \
 110                 default: __ret = __put_user_unaligned_unknown();                                \
 111         }                                                                                       \
 112         __ret;                                                                                  \
 113 })
 114
 115 extern long __get_user_unaligned_unknown (void);
 116
 117 #define __get_user_unaligned(x, ptr)                                                            \
 118 ({                                                                                              \
 119         long __ret;                                                                             \
 120         switch (sizeof(*(ptr))) {                                                               \
 121                 case 1: __ret = __get_user((x), (ptr)); break;                                  \
 122                 case 2: __ret = (__get_user((x), (u8 __user *)(ptr)))                           \
 123                         | (__get_user((x) >> 8, ((u8 __user *)(ptr) + 1))); break;              \
 124                 case 4: __ret = (__get_user((x), (u16 __user *)(ptr)))                          \
 125                         | (__get_user((x) >> 16, ((u16 __user *)(ptr) + 1))); break;            \
 126                 case 8: __ret = (__get_user((x), (u32 __user *)(ptr)))                          \
 127                         | (__get_user((x) >> 32, ((u32 __user *)(ptr) + 1))); break;            \
 128                 default: __ret = __get_user_unaligned_unknown();                                \
 129         }                                                                                       \
 130         __ret;                                                                                  \
 131 })
 132
 133 #ifdef ASM_SUPPORTED
 134   struct __large_struct { unsigned long buf[100]; };
 135 # define __m(x) (*(struct __large_struct *)(x))
 136
 137 /* We need to declare the __ex_table section before we can use it in .xdata.  */
 138 asm (".section \"__ex_table\", \"a\"\n\t.previous");
 139
 140 # define __get_user_size(val, addr, n, err)                                                     \
 141 do {                                                                                            \
 142         register long __gu_r8 asm ("r8") = 0;                                                   \
 143         register long __gu_r9 asm ("r9");                                                       \
 144         asm ("\n[1:]\tld"#n" %0=%2%P2\t// %0 and %1 get overwritten by exception handler\n"     \
 145              "\t.xdata4 \"__ex_table\", 1b-., 1f-.+4\n"                                         \
 146              "[1:]"                                                                             \
 147              : "=r"(__gu_r9), "=r"(__gu_r8) : "m"(__m(addr)), "1"(__gu_r8));                    \
 148         (err) = __gu_r8;                                                                        \
 149         (val) = __gu_r9;                                                                        \
 150 } while (0)
 151
 152 /*
 153  * The "__put_user_size()" macro tells gcc it reads from memory instead of writing it.  This
 154  * is because they do not write to any memory gcc knows about, so there are no aliasing
 155  * issues.
 156  */
 157 # define __put_user_size(val, addr, n, err)                                                     \
 158 do {                                                                                            \
 159         register long __pu_r8 asm ("r8") = 0;                                                   \
 160         asm volatile ("\n[1:]\tst"#n" %1=%r2%P1\t// %0 gets overwritten by exception handler\n" \
 161                       "\t.xdata4 \"__ex_table\", 1b-., 1f-.\n"                                  \
 162                       "[1:]"                                                                    \
 163                       : "=r"(__pu_r8) : "m"(__m(addr)), "rO"(val), "0"(__pu_r8));               \
 164         (err) = __pu_r8;                                                                        \
 165 } while (0)
 166
 167 #else /* !ASM_SUPPORTED */
 168 # define RELOC_TYPE     2       /* ip-rel */
 169 # define __get_user_size(val, addr, n, err)                             \
 170 do {                                                                    \
 171         __ld_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE);   \
 172         (err) = ia64_getreg(_IA64_REG_R8);                              \
 173         (val) = ia64_getreg(_IA64_REG_R9);                              \
 174 } while (0)
 175 # define __put_user_size(val, addr, n, err)                                                     \
 176 do {                                                                                            \
 177         __st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE, (unsigned long) (val));    \
 178         (err) = ia64_getreg(_IA64_REG_R8);                                                      \
 179 } while (0)
 180 #endif /* !ASM_SUPPORTED */
 181
 182 extern void __get_user_unknown (void);
 183
 184 /*
 185  * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
 186  * could clobber r8 and r9 (among others).  Thus, be careful not to evaluate it while
 187  * using r8/r9.
 188  */
 189 #define __do_get_user(check, x, ptr, size, segment)                                     \
 190 ({                                                                                      \
 191         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);                              \
 192         __typeof__ (size) __gu_size = (size);                                           \
 193         long __gu_err = -EFAULT, __gu_val = 0;                                          \
 194                                                                                         \
 195         if (!check || __access_ok(__gu_ptr, size, segment))                             \
 196                 switch (__gu_size) {                                                    \
 197                       case 1: __get_user_size(__gu_val, __gu_ptr, 1, __gu_err); break;  \
 198                       case 2: __get_user_size(__gu_val, __gu_ptr, 2, __gu_err); break;  \
 199                       case 4: __get_user_size(__gu_val, __gu_ptr, 4, __gu_err); break;  \
 200                       case 8: __get_user_size(__gu_val, __gu_ptr, 8, __gu_err); break;  \
 201                       default: __get_user_unknown(); break;                             \
 202                 }                                                                       \
 203         (x) = (__typeof__(*(__gu_ptr))) __gu_val;                                       \
 204         __gu_err;                                                                       \
 205 })
 206
 207 #define __get_user_nocheck(x, ptr, size)        __do_get_user(0, x, ptr, size, KERNEL_DS)
 208 #define __get_user_check(x, ptr, size, segment) __do_get_user(1, x, ptr, size, segment)
 209
 210 extern void __put_user_unknown (void);
 211
 212 /*
 213  * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
 214  * could clobber r8 (among others).  Thus, be careful not to evaluate them while using r8.
 215  */
 216 #define __do_put_user(check, x, ptr, size, segment)                                     \
 217 ({                                                                                      \
 218         __typeof__ (x) __pu_x = (x);                                                    \
 219         __typeof__ (*(ptr)) __user *__pu_ptr = (ptr);                                   \
 220         __typeof__ (size) __pu_size = (size);                                           \
 221         long __pu_err = -EFAULT;                                                        \
 222                                                                                         \
 223         if (!check || __access_ok(__pu_ptr, __pu_size, segment))                        \
 224                 switch (__pu_size) {                                                    \
 225                       case 1: __put_user_size(__pu_x, __pu_ptr, 1, __pu_err); break;    \
 226                       case 2: __put_user_size(__pu_x, __pu_ptr, 2, __pu_err); break;    \
 227                       case 4: __put_user_size(__pu_x, __pu_ptr, 4, __pu_err); break;    \
 228                       case 8: __put_user_size(__pu_x, __pu_ptr, 8, __pu_err); break;    \
 229                       default: __put_user_unknown(); break;                             \
 230                 }                                                                       \
 231         __pu_err;                                                                       \
 232 })
 233
 234 #define __put_user_nocheck(x, ptr, size)        __do_put_user(0, x, ptr, size, KERNEL_DS)
 235 #define __put_user_check(x, ptr, size, segment) __do_put_user(1, x, ptr, size, segment)
 236
 237 /*
 238  * Complex access routines
 239  */
 240 extern unsigned long __must_check __copy_user (void __user *to, const void __user *from,
 241                                                unsigned long count);
 242
 243 static inline unsigned long
 244 __copy_to_user (void __user *to, const void *from, unsigned long count)
 245 {
 246         return __copy_user(to, (void __user *) from, count);
 247 }
 248
 249 static inline unsigned long
 250 __copy_from_user (void *to, const void __user *from, unsigned long count)
 251 {
 252         return __copy_user((void __user *) to, from, count);
 253 }
 254
 255 #define __copy_to_user_inatomic         __copy_to_user
 256 #define __copy_from_user_inatomic       __copy_from_user
 257 #define copy_to_user(to, from, n)                                                       \
 258 ({                                                                                      \
 259         void __user *__cu_to = (to);                                                    \
 260         const void *__cu_from = (from);                                                 \
 261         long __cu_len = (n);                                                            \
 262                                                                                         \
 263         if (__access_ok(__cu_to, __cu_len, get_fs()))                                   \
 264                 __cu_len = __copy_user(__cu_to, (void __user *) __cu_from, __cu_len);   \
 265         __cu_len;                                                                       \
 266 })
 267
 268 #define copy_from_user(to, from, n)                                                     \
 269 ({                                                                                      \
 270         void *__cu_to = (to);                                                           \
 271         const void __user *__cu_from = (from);                                          \
 272         long __cu_len = (n);                                                            \
 273                                                                                         \
 274         __chk_user_ptr(__cu_from);                                                      \
 275         if (__access_ok(__cu_from, __cu_len, get_fs()))                                 \
 276                 __cu_len = __copy_user((void __user *) __cu_to, __cu_from, __cu_len);   \
 277         __cu_len;                                                                       \
 278 })
 279
 280 #define __copy_in_user(to, from, size)  __copy_user((to), (from), (size))
 281
 282 static inline unsigned long
 283 copy_in_user (void __user *to, const void __user *from, unsigned long n)
 284 {
 285         if (likely(access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n)))
 286                 n = __copy_user(to, from, n);
 287         return n;
 288 }
 289
 290 extern unsigned long __do_clear_user (void __user *, unsigned long);
 291
 292 #define __clear_user(to, n)             __do_clear_user(to, n)
 293
 294 #define clear_user(to, n)                                       \
 295 ({                                                              \
 296         unsigned long __cu_len = (n);                           \
 297         if (__access_ok(to, __cu_len, get_fs()))                \
 298                 __cu_len = __do_clear_user(to, __cu_len);       \
 299         __cu_len;                                               \
 300 })
 301
 302
 303 /*
 304  * Returns: -EFAULT if exception before terminator, N if the entire buffer filled, else
 305  * strlen.
 306  */
 307 extern long __must_check __strncpy_from_user (char *to, const char __user *from, long to_len);
 308
 309 #define strncpy_from_user(to, from, n)                                  \
 310 ({                                                                      \
 311         const char __user * __sfu_from = (from);                        \
 312         long __sfu_ret = -EFAULT;                                       \
 313         if (__access_ok(__sfu_from, 0, get_fs()))                       \
 314                 __sfu_ret = __strncpy_from_user((to), __sfu_from, (n)); \
 315         __sfu_ret;                                                      \
 316 })
 317
 318 /* Returns: 0 if bad, string length+1 (memory size) of string if ok */
 319 extern unsigned long __strlen_user (const char __user *);
 320
 321 #define strlen_user(str)                                \
 322 ({                                                      \
 323         const char __user *__su_str = (str);            \
 324         unsigned long __su_ret = 0;                     \
 325         if (__access_ok(__su_str, 0, get_fs()))         \
 326                 __su_ret = __strlen_user(__su_str);     \
 327         __su_ret;                                       \
 328 })
 329
 330 /*
 331  * Returns: 0 if exception before NUL or reaching the supplied limit
 332  * (N), a value greater than N if the limit would be exceeded, else
 333  * strlen.
 334  */
 335 extern unsigned long __strnlen_user (const char __user *, long);
 336
 337 #define strnlen_user(str, len)                                  \
 338 ({                                                              \
 339         const char __user *__su_str = (str);                    \
 340         unsigned long __su_ret = 0;                             \
 341         if (__access_ok(__su_str, 0, get_fs()))                 \
 342                 __su_ret = __strnlen_user(__su_str, len);       \
 343         __su_ret;                                               \
 344 })
 345
 346 /* Generic code can't deal with the location-relative format that we use for compactness.  */
 347 #define ARCH_HAS_SORT_EXTABLE
 348 #define ARCH_HAS_SEARCH_EXTABLE
 349
 350 struct exception_table_entry {
 351         int addr;       /* location-relative address of insn this fixup is for */
 352         int cont;       /* location-relative continuation addr.; if bit 2 is set, r9 is set to 0 */
 353 };
 354
 355 extern void ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e);
 356 extern const struct exception_table_entry *search_exception_tables (unsigned long addr);
 357
 358 static inline int
 359 ia64_done_with_exception (struct pt_regs *regs)
 360 {
 361         const struct exception_table_entry *e;
 362         e = search_exception_tables(regs->cr_iip + ia64_psr(regs)->ri);
 363         if (e) {
 364                 ia64_handle_exception(regs, e);
 365                 return 1;
 366         }
 367         return 0;
 368 }
 369
 370 #endif /* _ASM_IA64_UACCESS_H */