[patch 01/18] powerpc: Move stack randomization after syscall_enter_from_user_mode()

[Thomas Gleixner]

add_random_kstack_offset() is invoked before syscall_enter_from_user_mode()
establishes state. That's wrong because add_random_kstack_offset() calls
into instrumentable code.

Move it after syscall_enter_from_user_mode() to ensure that state is
correctly established.

Signed-off-by: Thomas Gleixner <tglx at kernel.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Shrikanth Hegde <sshegde at linux.ibm.com>
Cc: linuxppc-dev at lists.ozlabs.org
---
 arch/powerpc/kernel/syscall.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c
@@ -19,8 +19,8 @@ notrace long system_call_exception(struc
 	long ret;
 	syscall_fn f;
 
-	add_random_kstack_offset();
 	r0 = syscall_enter_from_user_mode(regs, r0);
+	add_random_kstack_offset();
 
 	if (unlikely(r0 >= NR_syscalls)) {
 		if (unlikely(trap_is_unsupported_scv(regs))) {