It is useful to manually copy metadata in order to describe the effects
of memmove()-like logic in uninstrumented code or inline asm. Introduce
kmsan_memmove_metadata() for this purpose.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 include/linux/kmsan-checks.h | 14 ++++++++++++++
 mm/kmsan/hooks.c             | 11 +++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/linux/kmsan-checks.h b/include/linux/kmsan-checks.h
index c4cae333deec..5218973f0ad0 100644
--- a/include/linux/kmsan-checks.h
+++ b/include/linux/kmsan-checks.h

@@ -61,6 +61,17 @@ void kmsan_check_memory(const void *address, size_t size);
 void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
                        size_t left);

+/**
+ * kmsan_memmove_metadata() - Copy kernel memory range metadata.
+ * @dst: start of the destination kernel memory range.
+ * @src: start of the source kernel memory range.
+ * @n:   size of the memory ranges.
+ *
+ * KMSAN will treat the destination range as if its contents were memmove()d
+ * from the source range.
+ */
+void kmsan_memmove_metadata(void *dst, const void *src, size_t n);