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         switch (sizeof(*(ptr))) {                                       \
 161         case 1:                                                         \
 162                 __get_user_x(1, __ret_gu, __val_gu, ptr);               \
 163                 break;                                                  \
 164         case 2:                                                         \
 165                 __get_user_x(2, __ret_gu, __val_gu, ptr);               \
 166                 break;                                                  \
 167         case 4:                                                         \
 168                 __get_user_x(4, __ret_gu, __val_gu, ptr);               \
 169                 break;                                                  \
 170         case 8:                                                         \
 171                 __get_user_8(__ret_gu, __val_gu, ptr);                  \
 172                 break;                                                  \
 173         default:                                                        \
 174                 __get_user_x(X, __ret_gu, __val_gu, ptr);               \
 175                 break;                                                  \
 176         }                                                               \
 177         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 178         __ret_gu;                                                       \
 179 })
 180
 181 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 182         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 183                      :"0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 184
 185
 186
 187 #ifdef CONFIG_X86_32
 188 #define __put_user_u64(x, addr, err)                                    \
 189         asm volatile("1:        movl %%eax,0(%2)\n"                     \
 190                      "2:        movl %%edx,4(%2)\n"                     \
 191                      "3:\n"                                             \
 192                      ".section .fixup,\"ax\"\n"                         \
 193                      "4:        movl %3,%0\n"                           \
 194                      "  jmp 3b\n"                                       \
 195                      ".previous\n"                                      \
 196                      _ASM_EXTABLE(1b, 4b)                               \
 197                      _ASM_EXTABLE(2b, 4b)                               \
 198                      : "=r" (err)                                       \
 199                      : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))
 200
 201 #define __put_user_x8(x, ptr, __ret_pu)                         \
 202         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 203                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 204 #else
 205 #define __put_user_u64(x, ptr, retval) \
 206         __put_user_asm(x, ptr, retval, "q", "", "Zr", -EFAULT)
 207 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 208 #endif
 209
 210 extern void __put_user_bad(void);
 211
 212 /*
 213  * Strange magic calling convention: pointer in %ecx,
 214  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 215  */
 216 extern void __put_user_1(void);
 217 extern void __put_user_2(void);
 218 extern void __put_user_4(void);
 219 extern void __put_user_8(void);
 220
 221 #ifdef CONFIG_X86_WP_WORKS_OK
 222
 223 /**
 224  * put_user: - Write a simple value into user space.
 225  * @x:   Value to copy to user space.
 226  * @ptr: Destination address, in user space.
 227  *
 228  * Context: User context only.  This function may sleep.
 229  *
 230  * This macro copies a single simple value from kernel space to user
 231  * space.  It supports simple types like char and int, but not larger
 232  * data types like structures or arrays.
 233  *
 234  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 235  * to the result of dereferencing @ptr.
 236  *
 237  * Returns zero on success, or -EFAULT on error.
 238  */
 239 #define put_user(x, ptr)                                        \
 240 ({                                                              \
 241         int __ret_pu;                                           \
 242         __typeof__(*(ptr)) __pu_val;                            \
 243         __chk_user_ptr(ptr);                                    \
 244         __pu_val = x;                                           \
 245         switch (sizeof(*(ptr))) {                               \
 246         case 1:                                                 \
 247                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 248                 break;                                          \
 249         case 2:                                                 \
 250                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 251                 break;                                          \
 252         case 4:                                                 \
 253                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 254                 break;                                          \
 255         case 8:                                                 \
 256                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 257                 break;                                          \
 258         default:                                                \
 259                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 260                 break;                                          \
 261         }                                                       \
 262         __ret_pu;                                               \
 263 })
 264
 265 #define __put_user_size(x, ptr, size, retval, errret)                   \
 266 do {                                                                    \
 267         retval = 0;                                                     \
 268         __chk_user_ptr(ptr);                                            \
 269         switch (size) {                                                 \
 270         case 1:                                                         \
 271                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 272                 break;                                                  \
 273         case 2:                                                         \
 274                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 275                 break;                                                  \
 276         case 4:                                                         \
 277                 __put_user_asm(x, ptr, retval, "l", "k",  "ir", errret);\
 278                 break;                                                  \
 279         case 8:                                                         \
 280                 __put_user_u64((__typeof__(*ptr))(x), ptr, retval);     \
 281                 break;                                                  \
 282         default:                                                        \
 283                 __put_user_bad();                                       \
 284         }                                                               \
 285 } while (0)
 286
 287 #else
 288
 289 #define __put_user_size(x, ptr, size, retval, errret)                   \
 290 do {                                                                    \
 291         __typeof__(*(ptr))__pus_tmp = x;                                \
 292         retval = 0;                                                     \
 293                                                                         \
 294         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))    \
 295                 retval = errret;                                        \
 296 } while (0)
 297
 298 #define put_user(x, ptr)                                        \
 299 ({                                                              \
 300         int __ret_pu;                                           \
 301         __typeof__(*(ptr))__pus_tmp = x;                        \
 302         __ret_pu = 0;                                           \
 303         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,         \
 304                                        sizeof(*(ptr))) != 0))   \
 305                 __ret_pu = -EFAULT;                             \
 306         __ret_pu;                                               \
 307 })
 308 #endif
 309
 310 #ifdef CONFIG_X86_32
 311 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 312 #else
 313 #define __get_user_asm_u64(x, ptr, retval, errret) \
 314          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 315 #endif
 316
 317 #define __get_user_size(x, ptr, size, retval, errret)                   \
 318 do {                                                                    \
 319         retval = 0;                                                     \
 320         __chk_user_ptr(ptr);                                            \
 321         switch (size) {                                                 \
 322         case 1:                                                         \
 323                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 324                 break;                                                  \
 325         case 2:                                                         \
 326                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 327                 break;                                                  \
 328         case 4:                                                         \
 329                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 330                 break;                                                  \
 331         case 8:                                                         \
 332                 __get_user_asm_u64(x, ptr, retval, errret);             \
 333                 break;                                                  \
 334         default:                                                        \
 335                 (x) = __get_user_bad();                                 \
 336         }                                                               \
 337 } while (0)
 338
 339 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 340         asm volatile("1:        mov"itype" %2,%"rtype"1\n"              \
 341                      "2:\n"                                             \
 342                      ".section .fixup,\"ax\"\n"                         \
 343                      "3:        mov %3,%0\n"                            \
 344                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 345                      "  jmp 2b\n"                                       \
 346                      ".previous\n"                                      \
 347                      _ASM_EXTABLE(1b, 3b)                               \
 348                      : "=r" (err), ltype(x)                             \
 349                      : "m" (__m(addr)), "i" (errret), "0" (err))
 350
 351 #define __put_user_nocheck(x, ptr, size)                        \
 352 ({                                                              \
 353         long __pu_err;                                          \
 354         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 355         __pu_err;                                               \
 356 })
 357
 358 #define __get_user_nocheck(x, ptr, size)                                \
 359 ({                                                                      \
 360         long __gu_err;                                                  \
 361         unsigned long __gu_val;                                         \
 362         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 363         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 364         __gu_err;                                                       \
 365 })
 366
 367 /* FIXME: this hack is definitely wrong -AK */
 368 struct __large_struct { unsigned long buf[100]; };
 369 #define __m(x) (*(struct __large_struct __user *)(x))
 370
 371 /*
 372  * Tell gcc we read from memory instead of writing: this is because
 373  * we do not write to any memory gcc knows about, so there are no
 374  * aliasing issues.
 375  */
 376 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 377         asm volatile("1:        mov"itype" %"rtype"1,%2\n"              \
 378                      "2:\n"                                             \
 379                      ".section .fixup,\"ax\"\n"                         \
 380                      "3:        mov %3,%0\n"                            \
 381                      "  jmp 2b\n"                                       \
 382                      ".previous\n"                                      \
 383                      _ASM_EXTABLE(1b, 3b)                               \
 384                      : "=r"(err)                                        \
 385                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 386 /**
 387  * __get_user: - Get a simple variable from user space, with less checking.
 388  * @x:   Variable to store result.
 389  * @ptr: Source address, in user space.
 390  *
 391  * Context: User context only.  This function may sleep.
 392  *
 393  * This macro copies a single simple variable from user space to kernel
 394  * space.  It supports simple types like char and int, but not larger
 395  * data types like structures or arrays.
 396  *
 397  * @ptr must have pointer-to-simple-variable type, and the result of
 398  * dereferencing @ptr must be assignable to @x without a cast.
 399  *
 400  * Caller must check the pointer with access_ok() before calling this
 401  * function.
 402  *
 403  * Returns zero on success, or -EFAULT on error.
 404  * On error, the variable @x is set to zero.
 405  */
 406
 407 #define __get_user(x, ptr)                                              \
 408         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 409 /**
 410  * __put_user: - Write a simple value into user space, with less checking.
 411  * @x:   Value to copy to user space.
 412  * @ptr: Destination address, in user space.
 413  *
 414  * Context: User context only.  This function may sleep.
 415  *
 416  * This macro copies a single simple value from kernel space to user
 417  * space.  It supports simple types like char and int, but not larger
 418  * data types like structures or arrays.
 419  *
 420  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 421  * to the result of dereferencing @ptr.
 422  *
 423  * Caller must check the pointer with access_ok() before calling this
 424  * function.
 425  *
 426  * Returns zero on success, or -EFAULT on error.
 427  */
 428
 429 #define __put_user(x, ptr)                                              \
 430         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 431
 432 #define __get_user_unaligned __get_user
 433 #define __put_user_unaligned __put_user
 434
 435 /*
 436  * movsl can be slow when source and dest are not both 8-byte aligned
 437  */
 438 #ifdef CONFIG_X86_INTEL_USERCOPY
 439 extern struct movsl_mask {
 440         int mask;
 441 } ____cacheline_aligned_in_smp movsl_mask;
 442 #endif
 443
 444 #define ARCH_HAS_NOCACHE_UACCESS 1
 445
 446 #ifdef CONFIG_X86_32
 447 # include "uaccess_32.h"
 448 #else
 449 # define ARCH_HAS_SEARCH_EXTABLE
 450 # include "uaccess_64.h"
 451 #endif
 452
 453 #endif
 454