kbuild: remove cc-option test of -fno-stack-protector

Some Makefiles already pass -fno-stack-protector unconditionally.
For example, arch/arm64/kernel/vdso/Makefile, arch/x86/xen/Makefile.

No problem report so far about hard-coding this option. So, we can
assume all supported compilers know -fno-stack-protector.

GCC 4.8 and Clang support this option (https://godbolt.org/z/_HDGzN)

Get rid of cc-option from -fno-stack-protector.

Remove CONFIG_CC_HAS_STACKPROTECTOR_NONE, which is always 'y'.

Note:
arch/mips/vdso/Makefile adds -fno-stack-protector twice, first
unconditionally, and second conditionally. I removed the second one.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

10 files changed, 14 insertions, 18 deletions

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 00e378de8bc0..89c3cdfba753 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -37,7 +37,7 @@ REALMODE_CFLAGS	:= $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING \
 		   -mno-mmx -mno-sse
 
 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding)
-REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector)
+REALMODE_CFLAGS += -fno-stack-protector
 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member)
 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4))
 export REALMODE_CFLAGS
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 7619742f91c9..c88a31569a5e 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -36,7 +36,7 @@ cflags-$(CONFIG_X86_64) := -mcmodel=small
 KBUILD_CFLAGS += $(cflags-y)
 KBUILD_CFLAGS += -mno-mmx -mno-sse
 KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
-KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
+KBUILD_CFLAGS += -fno-stack-protector
 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
 KBUILD_CFLAGS += -Wno-pointer-sign
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 04e65f0698f6..215376d975a2 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -82,7 +82,7 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE
 # optimize sibling calls.
 #
 CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
-       $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
+       $(filter -g%,$(KBUILD_CFLAGS)) -fno-stack-protector \
        -fno-omit-frame-pointer -foptimize-sibling-calls \
        -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
 
@@ -151,7 +151,7 @@ KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(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 += -m32 -msoft-float -mregparm=0 -fpic
-KBUILD_CFLAGS_32 += $(call cc-option, -fno-stack-protector)
+KBUILD_CFLAGS_32 += -fno-stack-protector
 KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls)
 KBUILD_CFLAGS_32 += -fno-omit-frame-pointer
 KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index dba6a83bc349..93792b457b81 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -17,8 +17,7 @@ KCOV_INSTRUMENT_perf_event.o := n
 KCSAN_SANITIZE_common.o := n
 
 # Make sure load_percpu_segment has no stackprotector
-nostackp := $(call cc-option, -fno-stack-protector)
-CFLAGS_common.o		:= $(nostackp)
+CFLAGS_common.o		:= -fno-stack-protector
 
 obj-y			:= cacheinfo.o scattered.o topology.o
 obj-y			+= common.o
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 6110bce7237b..d46fff11f06f 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -24,7 +24,7 @@ ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_cmdline.o = -pg
 endif
 
-CFLAGS_cmdline.o := $(call cc-option, -fno-stack-protector)
+CFLAGS_cmdline.o := -fno-stack-protector
 endif
 
 inat_tables_script = $(srctree)/arch/x86/tools/gen-insn-attr-x86.awk
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index f7fd0e868c9c..5864219221ca 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -22,10 +22,9 @@ obj-y				:=  init.o init_$(BITS).o fault.o ioremap.o extable.o mmap.o \
 obj-y				+= pat/
 
 # Make sure __phys_addr has no stackprotector
-nostackp := $(call cc-option, -fno-stack-protector)
-CFLAGS_physaddr.o		:= $(nostackp)
-CFLAGS_setup_nx.o		:= $(nostackp)
-CFLAGS_mem_encrypt_identity.o	:= $(nostackp)
+CFLAGS_physaddr.o		:= -fno-stack-protector
+CFLAGS_setup_nx.o		:= -fno-stack-protector
+CFLAGS_mem_encrypt_identity.o	:= -fno-stack-protector
 
 CFLAGS_fault.o := -I $(srctree)/$(src)/../include/asm/trace
 
diff --git a/arch/x86/power/Makefile b/arch/x86/power/Makefile
index 37923d715741..6907b523e856 100644
--- a/arch/x86/power/Makefile
+++ b/arch/x86/power/Makefile
@@ -3,8 +3,7 @@ OBJECT_FILES_NON_STANDARD_hibernate_asm_$(BITS).o := y
 
 # __restore_processor_state() restores %gs after S3 resume and so should not
 # itself be stack-protected
-nostackp := $(call cc-option, -fno-stack-protector)
-CFLAGS_cpu.o	:= $(nostackp)
+CFLAGS_cpu.o	:= -fno-stack-protector
 
 obj-$(CONFIG_PM_SLEEP)		+= cpu.o
 obj-$(CONFIG_HIBERNATION)	+= hibernate_$(BITS).o hibernate_asm_$(BITS).o hibernate.o
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 088bd764e0b7..183ac60e5990 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -34,7 +34,7 @@ KCOV_INSTRUMENT := n
 PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
 PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
-PURGATORY_CFLAGS += $(call cc-option,-fno-stack-protector)
+PURGATORY_CFLAGS += -fno-stack-protector
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
 # in turn leaves some undefined symbols like __fentry__ in purgatory and not
diff --git a/arch/x86/um/vdso/Makefile b/arch/x86/um/vdso/Makefile
index 0caddd6acb22..5943387e3f35 100644
--- a/arch/x86/um/vdso/Makefile
+++ b/arch/x86/um/vdso/Makefile
@@ -42,7 +42,7 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
 # optimize sibling calls.
 #
 CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
-       $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
+       $(filter -g%,$(KBUILD_CFLAGS)) -fno-stack-protector \
        -fno-omit-frame-pointer -foptimize-sibling-calls
 
 $(vobjs): KBUILD_CFLAGS += $(CFL)
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index 084de77a109e..5f1db522d06b 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -9,9 +9,8 @@ CFLAGS_REMOVE_irq.o = -pg
 endif
 
 # Make sure early boot has no stackprotector
-nostackp := $(call cc-option, -fno-stack-protector)
-CFLAGS_enlighten_pv.o		:= $(nostackp)
-CFLAGS_mmu_pv.o			:= $(nostackp)
+CFLAGS_enlighten_pv.o		:= -fno-stack-protector
+CFLAGS_mmu_pv.o			:= -fno-stack-protector
 
 obj-y				+= enlighten.o
 obj-y				+= mmu.o