linux-kernel - [PATCH 19/21] lto, x86: Disable LTO for realmode / vDSO / head64

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Date:   Mon, 27 Nov 2017 13:34:21 -0800
From:   Andi Kleen <andi@...stfloor.org>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, samitolvanen@...gle.com, alxmtvv@...il.com,
        linux-kbuild@...r.kernel.org, yamada.masahiro@...ionext.com,
        akpm@...ux-foundation.org, Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 19/21] lto, x86: Disable LTO for realmode / vDSO / head64

From: Andi Kleen <ak@...ux.intel.com>

These files all don't like being compiled with LTO. Disable
it for them.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/entry/vdso/Makefile | 3 +--
 arch/x86/kernel/Makefile     | 2 ++
 arch/x86/realmode/Makefile   | 1 +
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 1943aebadede..76caa1159ce1 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -3,7 +3,6 @@
 # Building vDSO images for x86.
 #
 
-KBUILD_CFLAGS += $(DISABLE_LTO)
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n
 OBJECT_FILES_NON_STANDARD	:= y
@@ -74,7 +73,7 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE
 CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
        $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
        -fno-omit-frame-pointer -foptimize-sibling-calls \
-       -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
+       -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO $(DISABLE_LTO)
 
 $(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
 
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 81bb565f4497..18106858d4c3 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -22,6 +22,8 @@ CFLAGS_REMOVE_early_printk.o = -pg
 CFLAGS_REMOVE_head64.o = -pg
 endif
 
+CFLAGS_head64.o += $(DISABLE_LTO)
+
 KASAN_SANITIZE_head$(BITS).o				:= n
 KASAN_SANITIZE_dumpstack.o				:= n
 KASAN_SANITIZE_dumpstack_$(BITS).o			:= n
diff --git a/arch/x86/realmode/Makefile b/arch/x86/realmode/Makefile
index 682c895753d9..719f423da3a0 100644
--- a/arch/x86/realmode/Makefile
+++ b/arch/x86/realmode/Makefile
@@ -6,6 +6,7 @@
 # for more details.
 #
 #
+KBUILD_CFLAGS += $(DISABLE_LTO)
 KASAN_SANITIZE			:= n
 OBJECT_FILES_NON_STANDARD	:= y
 
-- 
2.13.6