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 commit
829fe4aa9ac1 ("x86: Allow generating user-space headers without a
compiler") did.
Link: https://lkml.org/lkml/2018/12/4/206
Fixes: 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler
support")
Reported-by: Meelis Roos <mr...@linux.ee>
Signed-off-by: Masahiro Yamada <yamada.masah...@socionext.com>
---
Changes in v2:
- Revive ifdef CONFIG_RETPOLINE surrounding the KBUILD_CFLAGS addition
- Rephase the commit log a bit, hoping the cause of the issue will be clearer
arch/x86/Makefile | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f5d7f41..75ef499 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -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
--
2.7.4
