Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index c127f94..b5e329f 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -1,20 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Based on arch/arm/mm/context.c
  *
  * Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
  * Copyright (C) 2012 ARM Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <linux/bitops.h>
@@ -88,7 +77,7 @@
 	}
 }
 
-static void flush_context(unsigned int cpu)
+static void flush_context(void)
 {
 	int i;
 	u64 asid;
@@ -142,7 +131,7 @@
 	return hit;
 }
 
-static u64 new_context(struct mm_struct *mm, unsigned int cpu)
+static u64 new_context(struct mm_struct *mm)
 {
 	static u32 cur_idx = 1;
 	u64 asid = atomic64_read(&mm->context.id);
@@ -180,7 +169,7 @@
 	/* We're out of ASIDs, so increment the global generation count */
 	generation = atomic64_add_return_relaxed(ASID_FIRST_VERSION,
 						 &asid_generation);
-	flush_context(cpu);
+	flush_context();
 
 	/* We have more ASIDs than CPUs, so this will always succeed */
 	asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, 1);
@@ -196,6 +185,9 @@
 	unsigned long flags;
 	u64 asid, old_active_asid;
 
+	if (system_supports_cnp())
+		cpu_set_reserved_ttbr0();
+
 	asid = atomic64_read(&mm->context.id);
 
 	/*
@@ -223,7 +215,7 @@
 	/* Check that our ASID belongs to the current generation. */
 	asid = atomic64_read(&mm->context.id);
 	if ((asid ^ atomic64_read(&asid_generation)) >> asid_bits) {
-		asid = new_context(mm, cpu);
+		asid = new_context(mm);
 		atomic64_set(&mm->context.id, asid);
 	}