x86/kprobes: Remove trampoline_handler() prototype

mainline inclusion
from mainline-5.0-rc1
commit 4b1bacab
category: bugfix
bugzilla: 14017
CVE: NA

-------------------------------------------------

... and make it static. It is called only by the kretprobe_trampoline()
from asm.

It was marked __visible so that it is visible outside of the current
compilation unit but that is not needed as it is used only in this
compilation unit.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20181205162526.GB109259@gmail.comSigned-off-by: NHongbo Yao <yaohongbo@huawei.com>
Reviewed-by: NChen Zhou <chenzhou10@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/x86/kernel/kprobes/core.c

@@ -752,7 +752,7 @@ STACK_FRAME_NON_STANDARD(kretprobe_trampoline);
 /*
  * Called from kretprobe_trampoline
  */
-__visible __used void *trampoline_handler(struct pt_regs *regs)
+static __used void *trampoline_handler(struct pt_regs *regs)
 {
 	struct kretprobe_instance *ri = NULL;
 	struct hlist_head *head, empty_rp;