v4.19.13 snapshot.
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
new file mode 100644
index 0000000..9c5606d
--- /dev/null
+++ b/arch/x86/lib/usercopy_64.c
@@ -0,0 +1,229 @@
+/*
+ * User address space access functions.
+ *
+ * Copyright 1997 Andi Kleen <ak@muc.de>
+ * Copyright 1997 Linus Torvalds
+ * Copyright 2002 Andi Kleen <ak@suse.de>
+ */
+#include <linux/export.h>
+#include <linux/uaccess.h>
+#include <linux/highmem.h>
+
+/*
+ * Zero Userspace
+ */
+
+unsigned long __clear_user(void __user *addr, unsigned long size)
+{
+ long __d0;
+ might_fault();
+ /* no memory constraint because it doesn't change any memory gcc knows
+ about */
+ stac();
+ asm volatile(
+ " testq %[size8],%[size8]\n"
+ " jz 4f\n"
+ "0: movq $0,(%[dst])\n"
+ " addq $8,%[dst]\n"
+ " decl %%ecx ; jnz 0b\n"
+ "4: movq %[size1],%%rcx\n"
+ " testl %%ecx,%%ecx\n"
+ " jz 2f\n"
+ "1: movb $0,(%[dst])\n"
+ " incq %[dst]\n"
+ " decl %%ecx ; jnz 1b\n"
+ "2:\n"
+ ".section .fixup,\"ax\"\n"
+ "3: lea 0(%[size1],%[size8],8),%[size8]\n"
+ " jmp 2b\n"
+ ".previous\n"
+ _ASM_EXTABLE(0b,3b)
+ _ASM_EXTABLE(1b,2b)
+ : [size8] "=&c"(size), [dst] "=&D" (__d0)
+ : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr));
+ clac();
+ return size;
+}
+EXPORT_SYMBOL(__clear_user);
+
+unsigned long clear_user(void __user *to, unsigned long n)
+{
+ if (access_ok(VERIFY_WRITE, to, n))
+ return __clear_user(to, n);
+ return n;
+}
+EXPORT_SYMBOL(clear_user);
+
+/*
+ * Try to copy last bytes and clear the rest if needed.
+ * Since protection fault in copy_from/to_user is not a normal situation,
+ * it is not necessary to optimize tail handling.
+ */
+__visible unsigned long
+copy_user_handle_tail(char *to, char *from, unsigned len)
+{
+ for (; len; --len, to++) {
+ char c;
+
+ if (__get_user_nocheck(c, from++, sizeof(char)))
+ break;
+ if (__put_user_nocheck(c, to, sizeof(char)))
+ break;
+ }
+ clac();
+ return len;
+}
+
+/*
+ * Similar to copy_user_handle_tail, probe for the write fault point,
+ * but reuse __memcpy_mcsafe in case a new read error is encountered.
+ * clac() is handled in _copy_to_iter_mcsafe().
+ */
+__visible unsigned long
+mcsafe_handle_tail(char *to, char *from, unsigned len)
+{
+ for (; len; --len, to++, from++) {
+ /*
+ * Call the assembly routine back directly since
+ * memcpy_mcsafe() may silently fallback to memcpy.
+ */
+ unsigned long rem = __memcpy_mcsafe(to, from, 1);
+
+ if (rem)
+ break;
+ }
+ return len;
+}
+
+#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
+/**
+ * clean_cache_range - write back a cache range with CLWB
+ * @vaddr: virtual start address
+ * @size: number of bytes to write back
+ *
+ * Write back a cache range using the CLWB (cache line write back)
+ * instruction. Note that @size is internally rounded up to be cache
+ * line size aligned.
+ */
+static void clean_cache_range(void *addr, size_t size)
+{
+ u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
+ unsigned long clflush_mask = x86_clflush_size - 1;
+ void *vend = addr + size;
+ void *p;
+
+ for (p = (void *)((unsigned long)addr & ~clflush_mask);
+ p < vend; p += x86_clflush_size)
+ clwb(p);
+}
+
+void arch_wb_cache_pmem(void *addr, size_t size)
+{
+ clean_cache_range(addr, size);
+}
+EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
+
+long __copy_user_flushcache(void *dst, const void __user *src, unsigned size)
+{
+ unsigned long flushed, dest = (unsigned long) dst;
+ long rc = __copy_user_nocache(dst, src, size, 0);
+
+ /*
+ * __copy_user_nocache() uses non-temporal stores for the bulk
+ * of the transfer, but we need to manually flush if the
+ * transfer is unaligned. A cached memory copy is used when
+ * destination or size is not naturally aligned. That is:
+ * - Require 8-byte alignment when size is 8 bytes or larger.
+ * - Require 4-byte alignment when size is 4 bytes.
+ */
+ if (size < 8) {
+ if (!IS_ALIGNED(dest, 4) || size != 4)
+ clean_cache_range(dst, 1);
+ } else {
+ if (!IS_ALIGNED(dest, 8)) {
+ dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);
+ clean_cache_range(dst, 1);
+ }
+
+ flushed = dest - (unsigned long) dst;
+ if (size > flushed && !IS_ALIGNED(size - flushed, 8))
+ clean_cache_range(dst + size - 1, 1);
+ }
+
+ return rc;
+}
+
+void memcpy_flushcache(void *_dst, const void *_src, size_t size)
+{
+ unsigned long dest = (unsigned long) _dst;
+ unsigned long source = (unsigned long) _src;
+
+ /* cache copy and flush to align dest */
+ if (!IS_ALIGNED(dest, 8)) {
+ unsigned len = min_t(unsigned, size, ALIGN(dest, 8) - dest);
+
+ memcpy((void *) dest, (void *) source, len);
+ clean_cache_range((void *) dest, len);
+ dest += len;
+ source += len;
+ size -= len;
+ if (!size)
+ return;
+ }
+
+ /* 4x8 movnti loop */
+ while (size >= 32) {
+ asm("movq (%0), %%r8\n"
+ "movq 8(%0), %%r9\n"
+ "movq 16(%0), %%r10\n"
+ "movq 24(%0), %%r11\n"
+ "movnti %%r8, (%1)\n"
+ "movnti %%r9, 8(%1)\n"
+ "movnti %%r10, 16(%1)\n"
+ "movnti %%r11, 24(%1)\n"
+ :: "r" (source), "r" (dest)
+ : "memory", "r8", "r9", "r10", "r11");
+ dest += 32;
+ source += 32;
+ size -= 32;
+ }
+
+ /* 1x8 movnti loop */
+ while (size >= 8) {
+ asm("movq (%0), %%r8\n"
+ "movnti %%r8, (%1)\n"
+ :: "r" (source), "r" (dest)
+ : "memory", "r8");
+ dest += 8;
+ source += 8;
+ size -= 8;
+ }
+
+ /* 1x4 movnti loop */
+ while (size >= 4) {
+ asm("movl (%0), %%r8d\n"
+ "movnti %%r8d, (%1)\n"
+ :: "r" (source), "r" (dest)
+ : "memory", "r8");
+ dest += 4;
+ source += 4;
+ size -= 4;
+ }
+
+ /* cache copy for remaining bytes */
+ if (size) {
+ memcpy((void *) dest, (void *) source, size);
+ clean_cache_range((void *) dest, size);
+ }
+}
+EXPORT_SYMBOL_GPL(memcpy_flushcache);
+
+void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
+ size_t len)
+{
+ char *from = kmap_atomic(page);
+
+ memcpy_flushcache(to, from + offset, len);
+ kunmap_atomic(from);
+}
+#endif