Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"

This reverts commit 5bdcd510c2.

The macro based workarounds for GCC's inlining bugs caused regressions: distcc
and other distro build setups broke, and the fixes are not easy nor will they
solve regressions on already existing installations.

So we are reverting this patch and the 8 followup patches.

What makes this revert easier is that GCC9 will likely include the new 'asm inline'
syntax that makes inlining of assembly blocks a lot more robust.

This is a superior method to any macro based hackeries - and might even be
backported to GCC8, which would make all modern distros get the inlining
fixes as well.

Many thanks to Masahiro Yamada and others for helping sort out these problems.

Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Borislav Petkov <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Richard Biener <rguenther@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/entry/calling.h

@@ -352,7 +352,7 @@ For 32-bit we have the following conventions - kernel is built with
 .macro CALL_enter_from_user_mode
 #ifdef CONFIG_CONTEXT_TRACKING
 #ifdef HAVE_JUMP_LABEL
-	STATIC_BRANCH_JMP l_yes=.Lafter_call_\@, key=context_tracking_enabled, branch=1
+	STATIC_JUMP_IF_FALSE .Lafter_call_\@, context_tracking_enabled, def=0
 #endif
 	call enter_from_user_mode
 .Lafter_call_\@: