Commit 25896d07 authored Dec 05, 2018 by Masahiro Yamada Committed by Ingo Molnar Dec 05, 2018

x86/build: Fix compiler support check for CONFIG_RETPOLINE



It is troublesome to add a diagnostic like this to the Makefile
parse stage because the top-level Makefile could be parsed with
a stale include/config/auto.conf.

Once you are hit by the error about non-retpoline compiler, the
compilation still breaks even after disabling CONFIG_RETPOLINE.

The easiest fix is to move this check to the "archprepare" like
this commit did:

  829fe4aa ("x86: Allow generating user-space headers without a compiler")

Reported-by: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Fixes: 4cd24de3 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support")
Link: http://lkml.kernel.org/r/1543991239-18476-1-git-send-email-yamada.masahiro@socionext.com
Link: https://lkml.org/lkml/2018/12/4/206


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 182ddd16

arch/x86/Makefile

+7 −3

Original line number	Diff line number	Diff line
		@@ -220,9 +220,6 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables

		# Avoid indirect branches in kernel to deal with Spectre
		ifdef CONFIG_RETPOLINE
		ifeq ($(RETPOLINE_CFLAGS),)
		$(error You are building kernel with non-retpoline compiler, please update your compiler.)
		endif
		KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
		endif

		@@ -307,6 +304,13 @@ ifndef CC_HAVE_ASM_GOTO
		@echo Compiler lacks asm-goto support.
		@exit 1
		endif
		ifdef CONFIG_RETPOLINE
		ifeq ($(RETPOLINE_CFLAGS),)
		@echo "You are building kernel with non-retpoline compiler." >&2
		@echo "Please update your compiler." >&2
		@false
		endif
		endif

		archclean:
		$(Q)rm -rf $(objtree)/arch/i386

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