arch/x86/include/asm/uaccess_64.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_UACCESS_64_H
   3 #define _ASM_X86_UACCESS_64_H
   4
   5 /*
   6  * User space memory access functions
   7  */
   8 #include <linux/compiler.h>
   9 #include <linux/lockdep.h>
  10 #include <linux/kasan-checks.h>
  11 #include <asm/alternative.h>
  12 #include <asm/cpufeatures.h>
  13 #include <asm/page.h>
  14
  15 /*
  16  * Copy To/From Userspace
  17  */
  18
  19 /* Handles exceptions in both to and from, but doesn't do access_ok */
  20 __must_check unsigned long
  21 copy_user_fast_string(void *to, const void *from, unsigned len);
  22 __must_check unsigned long
  23 copy_user_generic_unrolled(void *to, const void *from, unsigned len);
  24
  25 static __always_inline __must_check unsigned long
  26 copy_user_generic(void *to, const void *from, unsigned len)
  27 {
  28         unsigned ret;
  29
  30         /*
  31          * If CPU has FSRM feature, use 'rep movs'.
  32          * Otherwise, use copy_user_generic_unrolled.
  33          */
  34         alternative_call(copy_user_generic_unrolled,
  35                          copy_user_fast_string,
  36                          X86_FEATURE_FSRM,
  37                          ASM_OUTPUT2("=a" (ret), "=D" (to), "=S" (from),
  38                                      "=d" (len)),
  39                          "1" (to), "2" (from), "3" (len)
  40                          : "memory", "rcx", "r8", "r9", "r10", "r11");
  41         return ret;
  42 }
  43
  44 static __always_inline __must_check unsigned long
  45 raw_copy_from_user(void *dst, const void __user *src, unsigned long size)
  46 {
  47         return copy_user_generic(dst, (__force void *)src, size);
  48 }
  49
  50 static __always_inline __must_check unsigned long
  51 raw_copy_to_user(void __user *dst, const void *src, unsigned long size)
  52 {
  53         return copy_user_generic((__force void *)dst, src, size);
  54 }
  55
  56 extern long __copy_user_nocache(void *dst, const void __user *src,
  57                                 unsigned size, int zerorest);
  58
  59 extern long __copy_user_flushcache(void *dst, const void __user *src, unsigned size);
  60 extern void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
  61                            size_t len);
  62
  63 static inline int
  64 __copy_from_user_inatomic_nocache(void *dst, const void __user *src,
  65                                   unsigned size)
  66 {
  67         kasan_check_write(dst, size);
  68         return __copy_user_nocache(dst, src, size, 0);
  69 }
  70
  71 static inline int
  72 __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
  73 {
  74         kasan_check_write(dst, size);
  75         return __copy_user_flushcache(dst, src, size);
  76 }
  77
  78 /*
  79  * Zero Userspace.
  80  */
  81
  82 __must_check unsigned long
  83 clear_user_original(void __user *addr, unsigned long len);
  84
  85 static __always_inline __must_check unsigned long __clear_user(void __user *addr, unsigned long size)
  86 {
  87         might_fault();
  88         stac();
  89
  90         /*
  91          * No memory constraint because it doesn't change any memory gcc
  92          * knows about.
  93          */
  94         asm volatile(
  95                 "1:\n\t"
  96                 ALTERNATIVE("rep stosb",
  97                             "call clear_user_original", ALT_NOT(X86_FEATURE_FSRS))
  98                 "2:\n"
  99                _ASM_EXTABLE_UA(1b, 2b)
 100                : "+c" (size), "+D" (addr), ASM_CALL_CONSTRAINT
 101                : "a" (0));
 102
 103         clac();
 104
 105         return size;
 106 }
 107
 108 static __always_inline unsigned long clear_user(void __user *to, unsigned long n)
 109 {
 110         if (access_ok(to, n))
 111                 return __clear_user(to, n);
 112         return n;
 113 }
 114 #endif /* _ASM_X86_UACCESS_64_H */