Use the new switch_to_permissive_pkey_reg() helper instead of the
custom code. No functional changes intended.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org

---
Changes in v3:
 - restore sig_prepare_pkru with the large comment and
   make it call the new write_permissive_pkey_val
---
 arch/x86/kernel/signal.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 5f441039b5725..27a66a0697dd2 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -28,6 +28,7 @@
 #include <linux/entry-common.h>
 #include <linux/syscalls.h>
 #include <linux/rseq.h>
+#include <linux/pkeys.h>
 
 #include <asm/processor.h>
 #include <asm/ucontext.h>
@@ -72,10 +73,7 @@ static inline int is_x32_frame(struct ksignal *ksig)
  */
 static inline u32 sig_prepare_pkru(void)
 {
-	u32 orig_pkru = read_pkru();
-
-	write_pkru(0);
-	return orig_pkru;
+	return write_permissive_pkey_val();
 }
 
 /*
-- 
2.48.1.658.g4767266eb4-goog