[tip:x86/urgent] x86: Allow generating user-space headers without a compiler

[tip-bot for Ben Hutchings]

Commit-ID:  829fe4aa9ac16417a904ad1de1307de906854bcf
Gitweb:     https://git.kernel.org/tip/829fe4aa9ac16417a904ad1de1307de906854bcf
Author:     Ben Hutchings <ben@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 29 Aug 2018 20:43:17 +0100
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 31 Aug 2018 17:08:22 +0200

x86: Allow generating user-space headers without a compiler

When bootstrapping an architecture, it's usual to generate the kernel's
user-space headers (make headers_install) before building a compiler.  Move
the compiler check (for asm goto support) to the archprepare target so that
it is only done when building code for the target.

Fixes: e501ce957a78 ("x86: Force asm-goto")
Reported-by: Helmut Grohne <helmutg@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20180829194317.GA4765@xxxxxxxxxxxxxxx


---
 arch/x86/Makefile | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 8fc8f94ef5f5..8f6e7eb8ae9f 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -175,10 +175,6 @@ ifdef CONFIG_FUNCTION_GRAPH_TRACER
   endif
 endif
 
-ifndef CC_HAVE_ASM_GOTO
-  $(error Compiler lacks asm-goto support.)
-endif
-
 ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
 	# This compiler flag is not supported by Clang:
 	KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
@@ -300,6 +296,13 @@ PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@
 
+archprepare: checkbin
+checkbin:
+ifndef CC_HAVE_ASM_GOTO
+	@echo Compiler lacks asm-goto support.
+	@exit 1
+endif
+
 archclean:
 	$(Q)rm -rf $(objtree)/arch/i386
 	$(Q)rm -rf $(objtree)/arch/x86_64