From: James Morse <james.morse@arm.com>
Date: Thu, 17 Oct 2019 18:43:00 +0100
Subject: arm64: compat: Workaround Neoverse-N1 #1542419 for compat user-space

Git-commit: 222fc0c8503d98cec3cb2bac2780cdd21a6e31c0
Patch-mainline: v5.5-rc1
References: jsc#ECO-561,jsc#SLE-10671

Compat user-space is unable to perform ICIMVAU instructions from
user-space. Instead it uses a compat-syscall. Add the workaround for
Neoverse-N1 #1542419 to this code path.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 arch/arm64/kernel/sys_compat.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/arch/arm64/kernel/sys_compat.c
+++ b/arch/arm64/kernel/sys_compat.c
@@ -19,6 +19,7 @@
  */
 
 #include <linux/compat.h>
+#include <linux/cpufeature.h>
 #include <linux/personality.h>
 #include <linux/sched.h>
 #include <linux/sched/signal.h>
@@ -27,6 +28,7 @@
 #include <linux/uaccess.h>
 
 #include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
 #include <asm/unistd.h>
 
 static long
@@ -40,6 +42,15 @@ __do_compat_cache_op(unsigned long start
 		if (fatal_signal_pending(current))
 			return 0;
 
+		if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) {
+			/*
+			 * The workaround requires an inner-shareable tlbi.
+			 * We pick the reserved-ASID to minimise the impact.
+			 */
+			__tlbi(aside1is, 0);
+			dsb(ish);
+		}
+
 		ret = __flush_cache_user_range(start, start + chunk);
 		if (ret)
 			return ret;