[patch 05/18] powerpc/syscall: Use syscall_enter_from_user_mode_randomize_stack()

syscall_enter_from_user_mode_randomize_stack() replaces
syscall_enter_from_user_mode() and the subsequent invocation of
add_random_kstack_offset().

The advantage is that it applies the stack randomization right after
enter_from_user_mode() and thereby avoids the overhead of get/put_cpu_var()
as that code is invoked with interrupts disabled.

No functional change.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Shrikanth Hegde <[email protected]>
Cc: [email protected]
---
 arch/powerpc/kernel/syscall.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c
@@ -2,7 +2,6 @@
 
 #include <linux/compat.h>
 #include <linux/context_tracking.h>
-#include <linux/randomize_kstack.h>
 #include <linux/entry-common.h>
 
 #include <asm/interrupt.h>
@@ -19,8 +18,7 @@ notrace long system_call_exception(struc
 	long ret;
 	syscall_fn f;
 
-	r0 = syscall_enter_from_user_mode(regs, r0);
-	add_random_kstack_offset();
+	r0 = syscall_enter_from_user_mode_randomize_stack(regs, r0);
 
 	if (unlikely(r0 >= NR_syscalls)) {
 		if (unlikely(trap_is_unsupported_scv(regs))) {