include/asm-x86/uaccess.h

   1 #ifndef _ASM_UACCES_H_
   2 #define _ASM_UACCES_H_
   3 /*
   4  * User space memory access functions
   5  */
   6 #include <linux/errno.h>
   7 #include <linux/compiler.h>
   8 #include <linux/thread_info.h>
   9 #include <linux/prefetch.h>
  10 #include <linux/string.h>
  11 #include <asm/asm.h>
  12 #include <asm/page.h>
  13
  14 #define VERIFY_READ 0
  15 #define VERIFY_WRITE 1
  16
  17 /*
  18  * The fs value determines whether argument validity checking should be
  19  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  20  * get_fs() == KERNEL_DS, checking is bypassed.
  21  *
  22  * For historical reasons, these macros are grossly misnamed.
  23  */
  24
  25 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  26
  27 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  28 #define USER_DS         MAKE_MM_SEG(PAGE_OFFSET)
  29
  30 #define get_ds()        (KERNEL_DS)
  31 #define get_fs()        (current_thread_info()->addr_limit)
  32 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  33
  34 #define segment_eq(a, b)        ((a).seg == (b).seg)
  35
  36 #define __addr_ok(addr)                                 \
  37         ((unsigned long __force)(addr) <                \
  38          (current_thread_info()->addr_limit.seg))
  39
  40 /*
  41  * Test whether a block of memory is a valid user space address.
  42  * Returns 0 if the range is valid, nonzero otherwise.
  43  *
  44  * This is equivalent to the following test:
  45  * (u33)addr + (u33)size >= (u33)current->addr_limit.seg (u65 for x86_64)
  46  *
  47  * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
  48  */
  49
  50 #define __range_not_ok(addr, size)                                      \
  51 ({                                                                      \
  52         unsigned long flag, roksum;                                     \
  53         __chk_user_ptr(addr);                                           \
  54         asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0"             \
  55             : "=&r" (flag), "=r" (roksum)                               \
  56             : "1" (addr), "g" ((long)(size)),                           \
  57               "rm" (current_thread_info()->addr_limit.seg));            \
  58         flag;                                                           \
  59 })
  60
  61 /**
  62  * access_ok: - Checks if a user space pointer is valid
  63  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  64  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  65  *        to write to a block, it is always safe to read from it.
  66  * @addr: User space pointer to start of block to check
  67  * @size: Size of block to check
  68  *
  69  * Context: User context only.  This function may sleep.
  70  *
  71  * Checks if a pointer to a block of memory in user space is valid.
  72  *
  73  * Returns true (nonzero) if the memory block may be valid, false (zero)
  74  * if it is definitely invalid.
  75  *
  76  * Note that, depending on architecture, this function probably just
  77  * checks that the pointer is in the user space range - after calling
  78  * this function, memory access functions may still return -EFAULT.
  79  */
  80 #define access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0))
  81
  82 /*
  83  * The exception table consists of pairs of addresses: the first is the
  84  * address of an instruction that is allowed to fault, and the second is
  85  * the address at which the program should continue.  No registers are
  86  * modified, so it is entirely up to the continuation code to figure out
  87  * what to do.
  88  *
  89  * All the routines below use bits of fixup code that are out of line
  90  * with the main instruction path.  This means when everything is well,
  91  * we don't even have to jump over them.  Further, they do not intrude
  92  * on our cache or tlb entries.
  93  */
  94
  95 struct exception_table_entry {
  96         unsigned long insn, fixup;
  97 };
  98
  99 extern int fixup_exception(struct pt_regs *regs);
 100
 101 /*
 102  * These are the main single-value transfer routines.  They automatically
 103  * use the right size if we just have the right pointer type.
 104  *
 105  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 106  * and yet we don't want to do any pointers, because that is too much
 107  * of a performance impact. Thus we have a few rather ugly macros here,
 108  * and hide all the ugliness from the user.
 109  *
 110  * The "__xxx" versions of the user access functions are versions that
 111  * do not verify the address space, that must have been done previously
 112  * with a separate "access_ok()" call (this is used when we do multiple
 113  * accesses to the same area of user memory).
 114  */
 115
 116 extern int __get_user_1(void);
 117 extern int __get_user_2(void);
 118 extern int __get_user_4(void);
 119 extern int __get_user_8(void);
 120 extern int __get_user_bad(void);
 121
 122 #define __get_user_x(size, ret, x, ptr)               \
 123         asm volatile("call __get_user_" #size         \
 124                      : "=a" (ret),"=d" (x)            \
 125                      : "0" (ptr))                     \
 126
 127 /* Careful: we have to cast the result to the type of the pointer
 128  * for sign reasons */
 129
 130 /**
 131  * get_user: - Get a simple variable from user space.
 132  * @x:   Variable to store result.
 133  * @ptr: Source address, in user space.
 134  *
 135  * Context: User context only.  This function may sleep.
 136  *
 137  * This macro copies a single simple variable from user space to kernel
 138  * space.  It supports simple types like char and int, but not larger
 139  * data types like structures or arrays.
 140  *
 141  * @ptr must have pointer-to-simple-variable type, and the result of
 142  * dereferencing @ptr must be assignable to @x without a cast.
 143  *
 144  * Returns zero on success, or -EFAULT on error.
 145  * On error, the variable @x is set to zero.
 146  */
 147 #ifdef CONFIG_X86_32
 148 #define __get_user_8(__ret_gu, __val_gu, ptr)                           \
 149                 __get_user_x(X, __ret_gu, __val_gu, ptr)
 150 #else
 151 #define __get_user_8(__ret_gu, __val_gu, ptr)                           \
 152                 __get_user_x(8, __ret_gu, __val_gu, ptr)
 153 #endif
 154
 155 #define get_user(x, ptr)                                                \
 156 ({                                                                      \
 157         int __ret_gu;                                                   \
 158         unsigned long __val_gu;                                         \
 159         __chk_user_ptr(ptr);                                            \
 160         might_fault();                                                  \
 161         switch (sizeof(*(ptr))) {                                       \
 162         case 1:                                                         \
 163                 __get_user_x(1, __ret_gu, __val_gu, ptr);               \
 164                 break;                                                  \
 165         case 2:                                                         \
 166                 __get_user_x(2, __ret_gu, __val_gu, ptr);               \
 167                 break;                                                  \
 168         case 4:                                                         \
 169                 __get_user_x(4, __ret_gu, __val_gu, ptr);               \
 170                 break;                                                  \
 171         case 8:                                                         \
 172                 __get_user_8(__ret_gu, __val_gu, ptr);                  \
 173                 break;                                                  \
 174         default:                                                        \
 175                 __get_user_x(X, __ret_gu, __val_gu, ptr);               \
 176                 break;                                                  \
 177         }                                                               \
 178         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 179         __ret_gu;                                                       \
 180 })
 181
 182 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 183         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 184                      :"0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 185
 186
 187
 188 #ifdef CONFIG_X86_32
 189 #define __put_user_u64(x, addr, err)                                    \
 190         asm volatile("1:        movl %%eax,0(%2)\n"                     \
 191                      "2:        movl %%edx,4(%2)\n"                     \
 192                      "3:\n"                                             \
 193                      ".section .fixup,\"ax\"\n"                         \
 194                      "4:        movl %3,%0\n"                           \
 195                      "  jmp 3b\n"                                       \
 196                      ".previous\n"                                      \
 197                      _ASM_EXTABLE(1b, 4b)                               \
 198                      _ASM_EXTABLE(2b, 4b)                               \
 199                      : "=r" (err)                                       \
 200                      : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))
 201
 202 #define __put_user_x8(x, ptr, __ret_pu)                         \
 203         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 204                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 205 #else
 206 #define __put_user_u64(x, ptr, retval) \
 207         __put_user_asm(x, ptr, retval, "q", "", "Zr", -EFAULT)
 208 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 209 #endif
 210
 211 extern void __put_user_bad(void);
 212
 213 /*
 214  * Strange magic calling convention: pointer in %ecx,
 215  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 216  */
 217 extern void __put_user_1(void);
 218 extern void __put_user_2(void);
 219 extern void __put_user_4(void);
 220 extern void __put_user_8(void);
 221
 222 #ifdef CONFIG_X86_WP_WORKS_OK
 223
 224 /**
 225  * put_user: - Write a simple value into user space.
 226  * @x:   Value to copy to user space.
 227  * @ptr: Destination address, in user space.
 228  *
 229  * Context: User context only.  This function may sleep.
 230  *
 231  * This macro copies a single simple value from kernel space to user
 232  * space.  It supports simple types like char and int, but not larger
 233  * data types like structures or arrays.
 234  *
 235  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 236  * to the result of dereferencing @ptr.
 237  *
 238  * Returns zero on success, or -EFAULT on error.
 239  */
 240 #define put_user(x, ptr)                                        \
 241 ({                                                              \
 242         int __ret_pu;                                           \
 243         __typeof__(*(ptr)) __pu_val;                            \
 244         __chk_user_ptr(ptr);                                    \
 245         might_fault();                                          \
 246         __pu_val = x;                                           \
 247         switch (sizeof(*(ptr))) {                               \
 248         case 1:                                                 \
 249                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 250                 break;                                          \
 251         case 2:                                                 \
 252                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 253                 break;                                          \
 254         case 4:                                                 \
 255                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 256                 break;                                          \
 257         case 8:                                                 \
 258                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 259                 break;                                          \
 260         default:                                                \
 261                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 262                 break;                                          \
 263         }                                                       \
 264         __ret_pu;                                               \
 265 })
 266
 267 #define __put_user_size(x, ptr, size, retval, errret)                   \
 268 do {                                                                    \
 269         retval = 0;                                                     \
 270         might_fault();                                                  \
 271         __chk_user_ptr(ptr);                                            \
 272         switch (size) {                                                 \
 273         case 1:                                                         \
 274                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 275                 break;                                                  \
 276         case 2:                                                         \
 277                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 278                 break;                                                  \
 279         case 4:                                                         \
 280                 __put_user_asm(x, ptr, retval, "l", "k",  "ir", errret);\
 281                 break;                                                  \
 282         case 8:                                                         \
 283                 __put_user_u64((__typeof__(*ptr))(x), ptr, retval);     \
 284                 break;                                                  \
 285         default:                                                        \
 286                 __put_user_bad();                                       \
 287         }                                                               \
 288 } while (0)
 289
 290 #else
 291
 292 #define __put_user_size(x, ptr, size, retval, errret)                   \
 293 do {                                                                    \
 294         __typeof__(*(ptr))__pus_tmp = x;                                \
 295         retval = 0;                                                     \
 296                                                                         \
 297         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))    \
 298                 retval = errret;                                        \
 299 } while (0)
 300
 301 #define put_user(x, ptr)                                        \
 302 ({                                                              \
 303         int __ret_pu;                                           \
 304         __typeof__(*(ptr))__pus_tmp = x;                        \
 305         __ret_pu = 0;                                           \
 306         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,         \
 307                                        sizeof(*(ptr))) != 0))   \
 308                 __ret_pu = -EFAULT;                             \
 309         __ret_pu;                                               \
 310 })
 311 #endif
 312
 313 #ifdef CONFIG_X86_32
 314 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 315 #else
 316 #define __get_user_asm_u64(x, ptr, retval, errret) \
 317          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 318 #endif
 319
 320 #define __get_user_size(x, ptr, size, retval, errret)                   \
 321 do {                                                                    \
 322         retval = 0;                                                     \
 323         might_fault();                                                  \
 324         __chk_user_ptr(ptr);                                            \
 325         switch (size) {                                                 \
 326         case 1:                                                         \
 327                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 328                 break;                                                  \
 329         case 2:                                                         \
 330                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 331                 break;                                                  \
 332         case 4:                                                         \
 333                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 334                 break;                                                  \
 335         case 8:                                                         \
 336                 __get_user_asm_u64(x, ptr, retval, errret);             \
 337                 break;                                                  \
 338         default:                                                        \
 339                 (x) = __get_user_bad();                                 \
 340         }                                                               \
 341 } while (0)
 342
 343 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 344         asm volatile("1:        mov"itype" %2,%"rtype"1\n"              \
 345                      "2:\n"                                             \
 346                      ".section .fixup,\"ax\"\n"                         \
 347                      "3:        mov %3,%0\n"                            \
 348                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 349                      "  jmp 2b\n"                                       \
 350                      ".previous\n"                                      \
 351                      _ASM_EXTABLE(1b, 3b)                               \
 352                      : "=r" (err), ltype(x)                             \
 353                      : "m" (__m(addr)), "i" (errret), "0" (err))
 354
 355 #define __put_user_nocheck(x, ptr, size)                        \
 356 ({                                                              \
 357         long __pu_err;                                          \
 358         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 359         __pu_err;                                               \
 360 })
 361
 362 #define __get_user_nocheck(x, ptr, size)                                \
 363 ({                                                                      \
 364         long __gu_err;                                                  \
 365         unsigned long __gu_val;                                         \
 366         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 367         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 368         __gu_err;                                                       \
 369 })
 370
 371 /* FIXME: this hack is definitely wrong -AK */
 372 struct __large_struct { unsigned long buf[100]; };
 373 #define __m(x) (*(struct __large_struct __user *)(x))
 374
 375 /*
 376  * Tell gcc we read from memory instead of writing: this is because
 377  * we do not write to any memory gcc knows about, so there are no
 378  * aliasing issues.
 379  */
 380 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 381         asm volatile("1:        mov"itype" %"rtype"1,%2\n"              \
 382                      "2:\n"                                             \
 383                      ".section .fixup,\"ax\"\n"                         \
 384                      "3:        mov %3,%0\n"                            \
 385                      "  jmp 2b\n"                                       \
 386                      ".previous\n"                                      \
 387                      _ASM_EXTABLE(1b, 3b)                               \
 388                      : "=r"(err)                                        \
 389                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 390 /**
 391  * __get_user: - Get a simple variable from user space, with less checking.
 392  * @x:   Variable to store result.
 393  * @ptr: Source address, in user space.
 394  *
 395  * Context: User context only.  This function may sleep.
 396  *
 397  * This macro copies a single simple variable from user space to kernel
 398  * space.  It supports simple types like char and int, but not larger
 399  * data types like structures or arrays.
 400  *
 401  * @ptr must have pointer-to-simple-variable type, and the result of
 402  * dereferencing @ptr must be assignable to @x without a cast.
 403  *
 404  * Caller must check the pointer with access_ok() before calling this
 405  * function.
 406  *
 407  * Returns zero on success, or -EFAULT on error.
 408  * On error, the variable @x is set to zero.
 409  */
 410
 411 #define __get_user(x, ptr)                                              \
 412         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 413 /**
 414  * __put_user: - Write a simple value into user space, with less checking.
 415  * @x:   Value to copy to user space.
 416  * @ptr: Destination address, in user space.
 417  *
 418  * Context: User context only.  This function may sleep.
 419  *
 420  * This macro copies a single simple value from kernel space to user
 421  * space.  It supports simple types like char and int, but not larger
 422  * data types like structures or arrays.
 423  *
 424  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 425  * to the result of dereferencing @ptr.
 426  *
 427  * Caller must check the pointer with access_ok() before calling this
 428  * function.
 429  *
 430  * Returns zero on success, or -EFAULT on error.
 431  */
 432
 433 #define __put_user(x, ptr)                                              \
 434         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 435
 436 #define __get_user_unaligned __get_user
 437 #define __put_user_unaligned __put_user
 438
 439 /*
 440  * movsl can be slow when source and dest are not both 8-byte aligned
 441  */
 442 #ifdef CONFIG_X86_INTEL_USERCOPY
 443 extern struct movsl_mask {
 444         int mask;
 445 } ____cacheline_aligned_in_smp movsl_mask;
 446 #endif
 447
 448 #define ARCH_HAS_NOCACHE_UACCESS 1
 449
 450 #ifdef CONFIG_X86_32
 451 # include "uaccess_32.h"
 452 #else
 453 # define ARCH_HAS_SEARCH_EXTABLE
 454 # include "uaccess_64.h"
 455 #endif
 456
 457 #endif
 458