linux/arch/x86/lib/usercopy_64.c
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   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
  16unsigned 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 $0,(%[dst])\n"
  27                "       addq   $8,%[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   $0,(%[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_UA(0b, 3b)
  41                _ASM_EXTABLE_UA(1b, 2b)
  42                : [size8] "=&c"(size), [dst] "=&D" (__d0)
  43                : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr));
  44        clac();
  45        return size;
  46}
  47EXPORT_SYMBOL(__clear_user);
  48
  49unsigned long clear_user(void __user *to, unsigned long n)
  50{
  51        if (access_ok(VERIFY_WRITE, to, n))
  52                return __clear_user(to, n);
  53        return n;
  54}
  55EXPORT_SYMBOL(clear_user);
  56
  57/*
  58 * Try to copy last bytes and clear the rest if needed.
  59 * Since protection fault in copy_from/to_user is not a normal situation,
  60 * it is not necessary to optimize tail handling.
  61 */
  62__visible unsigned long
  63copy_user_handle_tail(char *to, char *from, unsigned len)
  64{
  65        for (; len; --len, to++) {
  66                char c;
  67
  68                if (__get_user_nocheck(c, from++, sizeof(char)))
  69                        break;
  70                if (__put_user_nocheck(c, to, sizeof(char)))
  71                        break;
  72        }
  73        clac();
  74        return len;
  75}
  76
  77/*
  78 * Similar to copy_user_handle_tail, probe for the write fault point,
  79 * but reuse __memcpy_mcsafe in case a new read error is encountered.
  80 * clac() is handled in _copy_to_iter_mcsafe().
  81 */
  82__visible unsigned long
  83mcsafe_handle_tail(char *to, char *from, unsigned len)
  84{
  85        for (; len; --len, to++, from++) {
  86                /*
  87                 * Call the assembly routine back directly since
  88                 * memcpy_mcsafe() may silently fallback to memcpy.
  89                 */
  90                unsigned long rem = __memcpy_mcsafe(to, from, 1);
  91
  92                if (rem)
  93                        break;
  94        }
  95        return len;
  96}
  97
  98#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
  99/**
 100 * clean_cache_range - write back a cache range with CLWB
 101 * @vaddr:      virtual start address
 102 * @size:       number of bytes to write back
 103 *
 104 * Write back a cache range using the CLWB (cache line write back)
 105 * instruction. Note that @size is internally rounded up to be cache
 106 * line size aligned.
 107 */
 108static void clean_cache_range(void *addr, size_t size)
 109{
 110        u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
 111        unsigned long clflush_mask = x86_clflush_size - 1;
 112        void *vend = addr + size;
 113        void *p;
 114
 115        for (p = (void *)((unsigned long)addr & ~clflush_mask);
 116             p < vend; p += x86_clflush_size)
 117                clwb(p);
 118}
 119
 120void arch_wb_cache_pmem(void *addr, size_t size)
 121{
 122        clean_cache_range(addr, size);
 123}
 124EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
 125
 126long __copy_user_flushcache(void *dst, const void __user *src, unsigned size)
 127{
 128        unsigned long flushed, dest = (unsigned long) dst;
 129        long rc = __copy_user_nocache(dst, src, size, 0);
 130
 131        /*
 132         * __copy_user_nocache() uses non-temporal stores for the bulk
 133         * of the transfer, but we need to manually flush if the
 134         * transfer is unaligned. A cached memory copy is used when
 135         * destination or size is not naturally aligned. That is:
 136         *   - Require 8-byte alignment when size is 8 bytes or larger.
 137         *   - Require 4-byte alignment when size is 4 bytes.
 138         */
 139        if (size < 8) {
 140                if (!IS_ALIGNED(dest, 4) || size != 4)
 141                        clean_cache_range(dst, 1);
 142        } else {
 143                if (!IS_ALIGNED(dest, 8)) {
 144                        dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);
 145                        clean_cache_range(dst, 1);
 146                }
 147
 148                flushed = dest - (unsigned long) dst;
 149                if (size > flushed && !IS_ALIGNED(size - flushed, 8))
 150                        clean_cache_range(dst + size - 1, 1);
 151        }
 152
 153        return rc;
 154}
 155
 156void __memcpy_flushcache(void *_dst, const void *_src, size_t size)
 157{
 158        unsigned long dest = (unsigned long) _dst;
 159        unsigned long source = (unsigned long) _src;
 160
 161        /* cache copy and flush to align dest */
 162        if (!IS_ALIGNED(dest, 8)) {
 163                unsigned len = min_t(unsigned, size, ALIGN(dest, 8) - dest);
 164
 165                memcpy((void *) dest, (void *) source, len);
 166                clean_cache_range((void *) dest, len);
 167                dest += len;
 168                source += len;
 169                size -= len;
 170                if (!size)
 171                        return;
 172        }
 173
 174        /* 4x8 movnti loop */
 175        while (size >= 32) {
 176                asm("movq    (%0), %%r8\n"
 177                    "movq   8(%0), %%r9\n"
 178                    "movq  16(%0), %%r10\n"
 179                    "movq  24(%0), %%r11\n"
 180                    "movnti  %%r8,   (%1)\n"
 181                    "movnti  %%r9,  8(%1)\n"
 182                    "movnti %%r10, 16(%1)\n"
 183                    "movnti %%r11, 24(%1)\n"
 184                    :: "r" (source), "r" (dest)
 185                    : "memory", "r8", "r9", "r10", "r11");
 186                dest += 32;
 187                source += 32;
 188                size -= 32;
 189        }
 190
 191        /* 1x8 movnti loop */
 192        while (size >= 8) {
 193                asm("movq    (%0), %%r8\n"
 194                    "movnti  %%r8,   (%1)\n"
 195                    :: "r" (source), "r" (dest)
 196                    : "memory", "r8");
 197                dest += 8;
 198                source += 8;
 199                size -= 8;
 200        }
 201
 202        /* 1x4 movnti loop */
 203        while (size >= 4) {
 204                asm("movl    (%0), %%r8d\n"
 205                    "movnti  %%r8d,   (%1)\n"
 206                    :: "r" (source), "r" (dest)
 207                    : "memory", "r8");
 208                dest += 4;
 209                source += 4;
 210                size -= 4;
 211        }
 212
 213        /* cache copy for remaining bytes */
 214        if (size) {
 215                memcpy((void *) dest, (void *) source, size);
 216                clean_cache_range((void *) dest, size);
 217        }
 218}
 219EXPORT_SYMBOL_GPL(__memcpy_flushcache);
 220
 221void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
 222                size_t len)
 223{
 224        char *from = kmap_atomic(page);
 225
 226        memcpy_flushcache(to, from + offset, len);
 227        kunmap_atomic(from);
 228}
 229#endif
 230