diff --git a/include/asm-generic/early_ioremap.h b/include/asm-generic/early_ioremap.h
index a5de55c04fb2..e539f27ec51b 100644
--- a/include/asm-generic/early_ioremap.h
+++ b/include/asm-generic/early_ioremap.h
@@ -33,6 +33,12 @@ extern void early_ioremap_setup(void);
  */
 extern void early_ioremap_reset(void);
 
+/*
+ * Early copy from unmapped memory to kernel mapped memory.
+ */
+extern void copy_from_early_mem(void *dest, phys_addr_t src,
+				unsigned long size);
+
 #else
 static inline void early_ioremap_init(void) { }
 static inline void early_ioremap_setup(void) { }
diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c
index e10ccd299d66..a0baeb4be934 100644
--- a/mm/early_ioremap.c
+++ b/mm/early_ioremap.c
@@ -217,6 +217,28 @@ early_memremap(resource_size_t phys_addr, unsigned long size)
 	return (__force void *)__early_ioremap(phys_addr, size,
 					       FIXMAP_PAGE_NORMAL);
 }
+
+#define MAX_MAP_CHUNK	(NR_FIX_BTMAPS << PAGE_SHIFT)
+
+void __init copy_from_early_mem(void *dest, phys_addr_t src, unsigned long size)
+{
+	unsigned long slop, clen;
+	char *p;
+
+	while (size) {
+		slop = src & ~PAGE_MASK;
+		clen = size;
+		if (clen > MAX_MAP_CHUNK - slop)
+			clen = MAX_MAP_CHUNK - slop;
+		p = early_memremap(src & PAGE_MASK, clen + slop);
+		memcpy(dest, p + slop, clen);
+		early_memunmap(p, clen + slop);
+		dest += clen;
+		src += clen;
+		size -= clen;
+	}
+}
+
 #else /* CONFIG_MMU */
 
 void __init __iomem *