arch/x86/lib/usercopy_64.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * User address space access functions.
   4  *
   5  * Copyright 1997 Andi Kleen <ak@muc.de>
   6  * Copyright 1997 Linus Torvalds
   7  * Copyright 2002 Andi Kleen <ak@suse.de>
   8  */
   9 #include <linux/export.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/highmem.h>
  12 #include <linux/libnvdimm.h>
  13
  14 /*
  15  * Zero Userspace
  16  */
  17
  18 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
  19 /**
  20  * clean_cache_range - write back a cache range with CLWB
  21  * @vaddr:      virtual start address
  22  * @size:       number of bytes to write back
  23  *
  24  * Write back a cache range using the CLWB (cache line write back)
  25  * instruction. Note that @size is internally rounded up to be cache
  26  * line size aligned.
  27  */
  28 static void clean_cache_range(void *addr, size_t size)
  29 {
  30         u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
  31         unsigned long clflush_mask = x86_clflush_size - 1;
  32         void *vend = addr + size;
  33         void *p;
  34
  35         for (p = (void *)((unsigned long)addr & ~clflush_mask);
  36              p < vend; p += x86_clflush_size)
  37                 clwb(p);
  38 }
  39
  40 void arch_wb_cache_pmem(void *addr, size_t size)
  41 {
  42         clean_cache_range(addr, size);
  43 }
  44 EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
  45
  46 long __copy_user_flushcache(void *dst, const void __user *src, unsigned size)
  47 {
  48         unsigned long flushed, dest = (unsigned long) dst;
  49         long rc;
  50
  51         stac();
  52         rc = __copy_user_nocache(dst, src, size);
  53         clac();
  54
  55         /*
  56          * __copy_user_nocache() uses non-temporal stores for the bulk
  57          * of the transfer, but we need to manually flush if the
  58          * transfer is unaligned. A cached memory copy is used when
  59          * destination or size is not naturally aligned. That is:
  60          *   - Require 8-byte alignment when size is 8 bytes or larger.
  61          *   - Require 4-byte alignment when size is 4 bytes.
  62          */
  63         if (size < 8) {
  64                 if (!IS_ALIGNED(dest, 4) || size != 4)
  65                         clean_cache_range(dst, size);
  66         } else {
  67                 if (!IS_ALIGNED(dest, 8)) {
  68                         dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);
  69                         clean_cache_range(dst, 1);
  70                 }
  71
  72                 flushed = dest - (unsigned long) dst;
  73                 if (size > flushed && !IS_ALIGNED(size - flushed, 8))
  74                         clean_cache_range(dst + size - 1, 1);
  75         }
  76
  77         return rc;
  78 }
  79
  80 void __memcpy_flushcache(void *_dst, const void *_src, size_t size)
  81 {
  82         unsigned long dest = (unsigned long) _dst;
  83         unsigned long source = (unsigned long) _src;
  84
  85         /* cache copy and flush to align dest */
  86         if (!IS_ALIGNED(dest, 8)) {
  87                 size_t len = min_t(size_t, size, ALIGN(dest, 8) - dest);
  88
  89                 memcpy((void *) dest, (void *) source, len);
  90                 clean_cache_range((void *) dest, len);
  91                 dest += len;
  92                 source += len;
  93                 size -= len;
  94                 if (!size)
  95                         return;
  96         }
  97
  98         /* 4x8 movnti loop */
  99         while (size >= 32) {
 100                 asm("movq    (%0), %%r8\n"
 101                     "movq   8(%0), %%r9\n"
 102                     "movq  16(%0), %%r10\n"
 103                     "movq  24(%0), %%r11\n"
 104                     "movnti  %%r8,   (%1)\n"
 105                     "movnti  %%r9,  8(%1)\n"
 106                     "movnti %%r10, 16(%1)\n"
 107                     "movnti %%r11, 24(%1)\n"
 108                     :: "r" (source), "r" (dest)
 109                     : "memory", "r8", "r9", "r10", "r11");
 110                 dest += 32;
 111                 source += 32;
 112                 size -= 32;
 113         }
 114
 115         /* 1x8 movnti loop */
 116         while (size >= 8) {
 117                 asm("movq    (%0), %%r8\n"
 118                     "movnti  %%r8,   (%1)\n"
 119                     :: "r" (source), "r" (dest)
 120                     : "memory", "r8");
 121                 dest += 8;
 122                 source += 8;
 123                 size -= 8;
 124         }
 125
 126         /* 1x4 movnti loop */
 127         while (size >= 4) {
 128                 asm("movl    (%0), %%r8d\n"
 129                     "movnti  %%r8d,   (%1)\n"
 130                     :: "r" (source), "r" (dest)
 131                     : "memory", "r8");
 132                 dest += 4;
 133                 source += 4;
 134                 size -= 4;
 135         }
 136
 137         /* cache copy for remaining bytes */
 138         if (size) {
 139                 memcpy((void *) dest, (void *) source, size);
 140                 clean_cache_range((void *) dest, size);
 141         }
 142 }
 143 EXPORT_SYMBOL_GPL(__memcpy_flushcache);
 144 #endif