Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/csky/abiv2/cacheflush.c b/arch/csky/abiv2/cacheflush.c
new file mode 100644
index 0000000..5bb887b
--- /dev/null
+++ b/arch/csky/abiv2/cacheflush.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/cache.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <asm/cache.h>
+
+void flush_icache_page(struct vm_area_struct *vma, struct page *page)
+{
+	unsigned long start;
+
+	start = (unsigned long) kmap_atomic(page);
+
+	cache_wbinv_range(start, start + PAGE_SIZE);
+
+	kunmap_atomic((void *)start);
+}
+
+void flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
+			     unsigned long vaddr, int len)
+{
+	unsigned long kaddr;
+
+	kaddr = (unsigned long) kmap_atomic(page) + (vaddr & ~PAGE_MASK);
+
+	cache_wbinv_range(kaddr, kaddr + len);
+
+	kunmap_atomic((void *)kaddr);
+}
+
+void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
+		      pte_t *pte)
+{
+	unsigned long addr, pfn;
+	struct page *page;
+
+	pfn = pte_pfn(*pte);
+	if (unlikely(!pfn_valid(pfn)))
+		return;
+
+	page = pfn_to_page(pfn);
+	if (page == ZERO_PAGE(0))
+		return;
+
+	addr = (unsigned long) kmap_atomic(page);
+
+	cache_wbinv_range(addr, addr + PAGE_SIZE);
+
+	kunmap_atomic((void *) addr);
+}