[RFC PATCH v3 01/20] treewide: Filter out CC_FLAGS_CFI

From: Sami Tolvanen <samitolvanen@google.com>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	x86@kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Joao Moreira <joao@overdrivepizza.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [RFC PATCH v3 01/20] treewide: Filter out CC_FLAGS_CFI
Date: Fri, 10 Jun 2022 16:34:54 -0700	[thread overview]
Message-ID: <20220610233513.1798771-2-samitolvanen@google.com> (raw)
In-Reply-To: <20220610233513.1798771-1-samitolvanen@google.com>

In preparation for removing CC_FLAGS_CFI from CC_FLAGS_LTO, explicitly
filter out CC_FLAGS_CFI in all the makefiles where we currently filter
out CC_FLAGS_LTO.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 arch/arm64/kernel/vdso/Makefile       | 3 ++-
 arch/x86/entry/vdso/Makefile          | 3 ++-
 drivers/firmware/efi/libstub/Makefile | 2 ++
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index f6e25d7c346a..c7c123ed29cc 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -34,7 +34,8 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
 # kernel with CONFIG_WERROR enabled.
 CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
 				$(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \
-				$(CC_FLAGS_LTO) -Wmissing-prototypes -Wmissing-declarations
+				$(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
+				-Wmissing-prototypes -Wmissing-declarations
 KASAN_SANITIZE			:= n
 KCSAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index c2a8b76ae0bc..0148df4f0425 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -91,7 +91,7 @@ ifneq ($(RETPOLINE_VDSO_CFLAGS),)
 endif
 endif
 
-$(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
+$(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
 
 #
 # vDSO code runs in userspace and -pg doesn't help with profiling anyway.
@@ -152,6 +152,7 @@ KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_CFI),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic
 KBUILD_CFLAGS_32 += -fno-stack-protector
 KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls)
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index d0537573501e..234fb2910622 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -39,6 +39,8 @@ KBUILD_CFLAGS			:= $(cflags-y) -Os -DDISABLE_BRANCH_PROFILING \
 
 # remove SCS flags from all objects in this directory
 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
+# disable CFI
+KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))
 # disable LTO
 KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))
 
-- 
2.36.1.476.g0c4daa206d-goog

