x86/entry_64: TRACE_IRQS_OFF before re-enabling.

x86/entry_64: TRACE_IRQS_OFF before re-enabling.

Our TRACE_IRQS_OFF call introduced in d572bdfdeb7a (x86/entry: Stuff RSB
for entry to kernel for non-SMEP platform) is after we have already
called ENABLE_INTERRUPTS, resulting in:

WARNING: CPU: 1 PID: 1 at kernel/locking/lockdep.c:2639 trace_hardirqs_off_caller+0xb9/0x130()
DEBUG_LOCKS_WARN_ON(!irqs_disabled())
Modules linked in:
CPU: 1 PID: 1 Comm: init Not tainted 4.1.12+ #91
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014
 0000000000000009 ffff88011955fdd8 ffffffff815e4336 ffff88011955fe58
 ffff880119550000 ffff88011955fe28 ffffffff810b556a ffff88011955fe28
 ffffffff8112cd59 0000000000000000 ffffed00232abfc7 ffffffff81ab5f31
Call Trace:
 [<ffffffff815e4336>] dump_stack+0x86/0xc0
 [<ffffffff810b556a>] warn_slowpath_common+0xca/0xf0
 [<ffffffff8112cd59>] ? trace_hardirqs_off_caller+0xb9/0x130
 [<ffffffff81ab5f31>] ? system_call_after_swapgs+0x17b/0x18c
 [<ffffffff810b5620>] warn_slowpath_fmt+0x90/0xb0
 [<ffffffff810b5590>] ? warn_slowpath_common+0xf0/0xf0
 [<ffffffff8112b663>] ? up_read+0x23/0x40
 [<ffffffff81133142>] ? mark_held_locks+0x22/0xd0
 [<ffffffff810a0150>] ? __do_page_fault+0x440/0x540
 [<ffffffff8112cd59>] trace_hardirqs_off_caller+0xb9/0x130
 [<ffffffff815fbbc1>] trace_hardirqs_off_thunk+0x17/0x19
 [<ffffffff81ab5f31>] ? system_call_after_swapgs+0x17b/0x18c

Move TRACE_IRQS_OFF to before interrupts have been re-enabled.

Orabug: 27344012
CVE:CVE-2017-5715

Signed-off-by: Jamie Iles <jamie.iles@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>
Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>