linux-kernel - [PATCH] jump label: fix passing kbuild_cflags when checking for asm goto support

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Date:   Fri, 10 Mar 2017 19:24:18 +0300
From:   Gleb Fotengauer-Malinovskiy <glebfm@...linux.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     David Lin <dtwlin@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        "Anton V. Boyarshinov" <boyarsh@...linux.org>,
        "Dmitry V. Levin" <ldv@...linux.org>,
        Michal Marek <mmarek@...e.com>, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] jump label: fix passing kbuild_cflags when checking for asm
 goto support

The latest change of asm goto support check added passing of
KBUILD_CFLAGS to compiler.  When these flags reference gcc plugins,
there is a race condition between the build of these plugins and their
use in this asm goto support check.

This change moves the check before all these references are added
to KBUILD_CFLAGS.  This is correct because subsequent KBUILD_CFLAGS
modifications are not relevant to this check.

Reported-by: Anton V. Boyarshinov <boyarsh@...linux.org>
Fixes: 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")
Cc: stable@...r.kernel.org	# v4.10
Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@...linux.org>
Signed-off-by: Dmitry V. Levin <ldv@...linux.org>
---
 Makefile | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 165cf97..7e3aade 100644
--- a/Makefile
+++ b/Makefile
@@ -653,6 +653,12 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
 
+# check for 'asm goto'
+ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
+	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
 include scripts/Makefile.gcc-plugins
 
 ifdef CONFIG_READABLE_ASM
@@ -798,12 +804,6 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=incompatible-pointer-types)
 # use the deterministic mode of AR if available
 KBUILD_ARFLAGS := $(call ar-option,D)
 
-# check for 'asm goto'
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
-	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
-	KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
-endif
-
 include scripts/Makefile.kasan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan

-- 
glebfm