x86/mce: Make machine check speculation protected

x86/mce: Make machine check speculation protected

commit 6f41c34d69eb005e7848716bbcafc979b35037d5 upstream.

The machine check idtentry uses an indirect branch directly from the low
level code. This evades the speculation protection.

Replace it by a direct call into C code and issue the indirect call there
so the compiler can apply the proper speculation protection.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by:Borislav Petkov <bp@alien8.de>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Niced-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801181626290.1847@nanos
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit f59e7ce17ba327245c8feb312d447b09d3b98eba)
Orabug: 27477743
CVE: CVE-2017-5715
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Conflicts:
	arch/x86/kernel/entry_64.S
	  (dmj: patch had arch/x86/entry/entry_64.S)
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>