Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
new file mode 100644
index 0000000..24cd33d
--- /dev/null
+++ b/arch/riscv/mm/tlbflush.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <asm/sbi.h>
+
+void flush_tlb_all(void)
+{
+	sbi_remote_sfence_vma(NULL, 0, -1);
+}
+
+static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start,
+				  unsigned long size)
+{
+	struct cpumask hmask;
+
+	riscv_cpuid_to_hartid_mask(cmask, &hmask);
+	sbi_remote_sfence_vma(hmask.bits, start, size);
+}
+
+void flush_tlb_mm(struct mm_struct *mm)
+{
+	__sbi_tlb_flush_range(mm_cpumask(mm), 0, -1);
+}
+
+void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
+{
+	__sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), addr, PAGE_SIZE);
+}
+
+void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+		     unsigned long end)
+{
+	__sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), start, end - start);
+}