1 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c
new file mode 100644
index 000000000..5a53c2cc1
--- /dev/null
+++ b/arch/x86/mm/maccess.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/uaccess.h>
+#include <linux/kernel.h>
+
+#ifdef CONFIG_X86_64
+bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
+{
+	unsigned long vaddr = (unsigned long)unsafe_src;
+
+	/*
+	 * Range covering the highest possible canonical userspace address
+	 * as well as non-canonical address range. For the canonical range
+	 * we also need to include the userspace guard page.
+	 */
+	return vaddr >= TASK_SIZE_MAX + PAGE_SIZE &&
+	       __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits);
+}
+#else
+bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
+{
+	return (unsigned long)unsafe_src >= TASK_SIZE_MAX;
+}
+#endif