arch/x86/lib/usercopy_64.c

   1 /*
   2  * User address space access functions.
   3  *
   4  * Copyright 1997 Andi Kleen <ak@muc.de>
   5  * Copyright 1997 Linus Torvalds
   6  * Copyright 2002 Andi Kleen <ak@suse.de>
   7  */
   8 #include <linux/export.h>
   9 #include <linux/uaccess.h>
  10 #include <linux/highmem.h>
  11
  12 /*
  13  * Zero Userspace
  14  */
  15
  16 unsigned long __clear_user(void __user *addr, unsigned long size)
  17 {
  18         long __d0;
  19         might_fault();
  20         /* no memory constraint because it doesn't change any memory gcc knows
  21            about */
  22         stac();
  23         asm volatile(
  24                 "       testq  %[size8],%[size8]\n"
  25                 "       jz     4f\n"
  26                 "0:     movq %[zero],(%[dst])\n"
  27                 "       addq   %[eight],%[dst]\n"
  28                 "       decl %%ecx ; jnz   0b\n"
  29                 "4:     movq  %[size1],%%rcx\n"
  30                 "       testl %%ecx,%%ecx\n"
  31                 "       jz     2f\n"
  32                 "1:     movb   %b[zero],(%[dst])\n"
  33                 "       incq   %[dst]\n"
  34                 "       decl %%ecx ; jnz  1b\n"
  35                 "2:\n"
  36                 ".section .fixup,\"ax\"\n"
  37                 "3:     lea 0(%[size1],%[size8],8),%[size8]\n"
  38                 "       jmp 2b\n"
  39                 ".previous\n"
  40                 _ASM_EXTABLE(0b,3b)
  41                 _ASM_EXTABLE(1b,2b)
  42                 : [size8] "=&c"(size), [dst] "=&D" (__d0)
  43                 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
  44                   [zero] "r" (0UL), [eight] "r" (8UL));
  45         clac();
  46         return size;
  47 }
  48 EXPORT_SYMBOL(__clear_user);
  49
  50 unsigned long clear_user(void __user *to, unsigned long n)
  51 {
  52         if (access_ok(VERIFY_WRITE, to, n))
  53                 return __clear_user(to, n);
  54         return n;
  55 }
  56 EXPORT_SYMBOL(clear_user);
  57
  58 /*
  59  * Try to copy last bytes and clear the rest if needed.
  60  * Since protection fault in copy_from/to_user is not a normal situation,
  61  * it is not necessary to optimize tail handling.
  62  */
  63 __visible unsigned long
  64 copy_user_handle_tail(char *to, char *from, unsigned len)
  65 {
  66         for (; len; --len, to++) {
  67                 char c;
  68
  69                 if (__get_user_nocheck(c, from++, sizeof(char)))
  70                         break;
  71                 if (__put_user_nocheck(c, to, sizeof(char)))
  72                         break;
  73         }
  74         clac();
  75         return len;
  76 }
  77
  78 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
  79 /**
  80  * clean_cache_range - write back a cache range with CLWB
  81  * @vaddr:      virtual start address
  82  * @size:       number of bytes to write back
  83  *
  84  * Write back a cache range using the CLWB (cache line write back)
  85  * instruction. Note that @size is internally rounded up to be cache
  86  * line size aligned.
  87  */
  88 static void clean_cache_range(void *addr, size_t size)
  89 {
  90         u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
  91         unsigned long clflush_mask = x86_clflush_size - 1;
  92         void *vend = addr + size;
  93         void *p;
  94
  95         for (p = (void *)((unsigned long)addr & ~clflush_mask);
  96              p < vend; p += x86_clflush_size)
  97                 clwb(p);
  98 }
  99
 100 void arch_wb_cache_pmem(void *addr, size_t size)
 101 {
 102         clean_cache_range(addr, size);
 103 }
 104 EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
 105
 106 long __copy_user_flushcache(void *dst, const void __user *src, unsigned size)
 107 {
 108         unsigned long flushed, dest = (unsigned long) dst;
 109         long rc = __copy_user_nocache(dst, src, size, 0);
 110
 111         /*
 112          * __copy_user_nocache() uses non-temporal stores for the bulk
 113          * of the transfer, but we need to manually flush if the
 114          * transfer is unaligned. A cached memory copy is used when
 115          * destination or size is not naturally aligned. That is:
 116          *   - Require 8-byte alignment when size is 8 bytes or larger.
 117          *   - Require 4-byte alignment when size is 4 bytes.
 118          */
 119         if (size < 8) {
 120                 if (!IS_ALIGNED(dest, 4) || size != 4)
 121                         clean_cache_range(dst, 1);
 122         } else {
 123                 if (!IS_ALIGNED(dest, 8)) {
 124                         dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);
 125                         clean_cache_range(dst, 1);
 126                 }
 127
 128                 flushed = dest - (unsigned long) dst;
 129                 if (size > flushed && !IS_ALIGNED(size - flushed, 8))
 130                         clean_cache_range(dst + size - 1, 1);
 131         }
 132
 133         return rc;
 134 }
 135
 136 void memcpy_flushcache(void *_dst, const void *_src, size_t size)
 137 {
 138         unsigned long dest = (unsigned long) _dst;
 139         unsigned long source = (unsigned long) _src;
 140
 141         /* cache copy and flush to align dest */
 142         if (!IS_ALIGNED(dest, 8)) {
 143                 unsigned len = min_t(unsigned, size, ALIGN(dest, 8) - dest);
 144
 145                 memcpy((void *) dest, (void *) source, len);
 146                 clean_cache_range((void *) dest, len);
 147                 dest += len;
 148                 source += len;
 149                 size -= len;
 150                 if (!size)
 151                         return;
 152         }
 153
 154         /* 4x8 movnti loop */
 155         while (size >= 32) {
 156                 asm("movq    (%0), %%r8\n"
 157                     "movq   8(%0), %%r9\n"
 158                     "movq  16(%0), %%r10\n"
 159                     "movq  24(%0), %%r11\n"
 160                     "movnti  %%r8,   (%1)\n"
 161                     "movnti  %%r9,  8(%1)\n"
 162                     "movnti %%r10, 16(%1)\n"
 163                     "movnti %%r11, 24(%1)\n"
 164                     :: "r" (source), "r" (dest)
 165                     : "memory", "r8", "r9", "r10", "r11");
 166                 dest += 32;
 167                 source += 32;
 168                 size -= 32;
 169         }
 170
 171         /* 1x8 movnti loop */
 172         while (size >= 8) {
 173                 asm("movq    (%0), %%r8\n"
 174                     "movnti  %%r8,   (%1)\n"
 175                     :: "r" (source), "r" (dest)
 176                     : "memory", "r8");
 177                 dest += 8;
 178                 source += 8;
 179                 size -= 8;
 180         }
 181
 182         /* 1x4 movnti loop */
 183         while (size >= 4) {
 184                 asm("movl    (%0), %%r8d\n"
 185                     "movnti  %%r8d,   (%1)\n"
 186                     :: "r" (source), "r" (dest)
 187                     : "memory", "r8");
 188                 dest += 4;
 189                 source += 4;
 190                 size -= 4;
 191         }
 192
 193         /* cache copy for remaining bytes */
 194         if (size) {
 195                 memcpy((void *) dest, (void *) source, size);
 196                 clean_cache_range((void *) dest, size);
 197         }
 198 }
 199 EXPORT_SYMBOL_GPL(memcpy_flushcache);
 200
 201 void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
 202                 size_t len)
 203 {
 204         char *from = kmap_atomic(page);
 205
 206         memcpy_flushcache(to, from + offset, len);
 207         kunmap_atomic(from);
 208 }
 209 #endif