On Sat, Jun 27, 2020 at 4:09 AM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > > On Fri, Jun 26, 2020 at 12:00 PM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote: > > > > 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 should always be '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@xxxxxxxxxx> > > --- > > > > Documentation/kbuild/kconfig-language.rst | 4 ++-- > > Makefile | 2 +- > > arch/Kconfig | 3 --- > > arch/arm/boot/compressed/Makefile | 3 +-- > > arch/mips/vdso/Makefile | 3 +-- > > arch/powerpc/kernel/Makefile | 2 +- > > arch/powerpc/platforms/powermac/Makefile | 2 +- > > arch/sparc/vdso/Makefile | 4 ++-- > > arch/um/Makefile | 3 +-- > > arch/x86/Makefile | 2 +- > > arch/x86/boot/compressed/Makefile | 2 +- > > arch/x86/entry/vdso/Makefile | 4 ++-- > > arch/x86/kernel/cpu/Makefile | 3 +-- > > arch/x86/lib/Makefile | 2 +- > > arch/x86/mm/Makefile | 7 +++---- > > arch/x86/power/Makefile | 3 +-- > > arch/x86/purgatory/Makefile | 2 +- > > arch/x86/um/vdso/Makefile | 2 +- > > arch/x86/xen/Makefile | 5 ++--- > > drivers/firmware/efi/libstub/Makefile | 2 +- > > drivers/xen/Makefile | 3 +-- > > kernel/kcsan/Makefile | 3 +-- > > lib/Makefile | 4 ++-- > > mm/kasan/Makefile | 2 +- > > 24 files changed, 30 insertions(+), 42 deletions(-) > > > > diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst > > index a1601ec3317b..2538e7cb08e6 100644 > > --- a/Documentation/kbuild/kconfig-language.rst > > +++ b/Documentation/kbuild/kconfig-language.rst > > @@ -540,8 +540,8 @@ followed by a test macro:: > > If you need to expose a compiler capability to makefiles and/or C source files, > > `CC_HAS_` is the recommended prefix for the config option:: > > > > - config CC_HAS_STACKPROTECTOR_NONE > > - def_bool $(cc-option,-fno-stack-protector) > > + config CC_HAS_ASM_GOTO > > + def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) > > > > Build as module only > > ~~~~~~~~~~~~~~~~~~~~ > > diff --git a/Makefile b/Makefile > > index 5496a32dffa6..73948798ce3f 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -762,7 +762,7 @@ ifneq ($(CONFIG_FRAME_WARN),0) > > KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN) > > endif > > > > -stackp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector > > +stackp-flags-y := -fno-stack-protector > > stackp-flags-$(CONFIG_STACKPROTECTOR) := -fstack-protector > > stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > > > > diff --git a/arch/Kconfig b/arch/Kconfig > > index 8cc35dc556c7..1ea61290900a 100644 > > --- a/arch/Kconfig > > +++ b/arch/Kconfig > > @@ -478,9 +478,6 @@ config HAVE_STACKPROTECTOR > > An arch should select this symbol if: > > - it has implemented a stack canary (e.g. __stack_chk_guard) > > > > -config CC_HAS_STACKPROTECTOR_NONE > > - def_bool $(cc-option,-fno-stack-protector) > > - > > config STACKPROTECTOR > > bool "Stack Protector buffer overflow detection" > > depends on HAVE_STACKPROTECTOR > > diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile > > index 00602a6fba04..cb7a56c6723c 100644 > > --- a/arch/arm/boot/compressed/Makefile > > +++ b/arch/arm/boot/compressed/Makefile > > @@ -84,9 +84,8 @@ endif > > > > # -fstack-protector-strong triggers protection checks in this code, > > # but it is being used too early to link to meaningful stack_chk logic. > > -nossp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector > > $(foreach o, $(libfdt_objs) atags_to_fdt.o, \ > > - $(eval CFLAGS_$(o) := -I $(srctree)/scripts/dtc/libfdt $(nossp-flags-y))) > > + $(eval CFLAGS_$(o) := -I $(srctree)/scripts/dtc/libfdt -fno-stack-protector)) > > > > # These were previously generated C files. When you are building the kernel > > # with O=, make sure to remove the stale files in the output tree. Otherwise, > > diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile > > index 2e64c7600eea..57fe83235281 100644 > > --- a/arch/mips/vdso/Makefile > > +++ b/arch/mips/vdso/Makefile > > @@ -35,8 +35,7 @@ cflags-vdso := $(ccflags-vdso) \ > > -O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \ > > -mrelax-pic-calls $(call cc-option, -mexplicit-relocs) \ > > -fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \ > > - $(call cc-option, -fno-asynchronous-unwind-tables) \ > > - $(call cc-option, -fno-stack-protector) > > + $(call cc-option, -fno-asynchronous-unwind-tables) > > aflags-vdso := $(ccflags-vdso) \ > > -D__ASSEMBLY__ -Wa,-gdwarf-2 > > > > diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile > > index 244542ae2a91..3a83f2b876a5 100644 > > --- a/arch/powerpc/kernel/Makefile > > +++ b/arch/powerpc/kernel/Makefile > > @@ -16,7 +16,7 @@ CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) > > CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) > > CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) > > > > -CFLAGS_prom_init.o += $(call cc-option, -fno-stack-protector) > > +CFLAGS_prom_init.o += -fno-stack-protector > > CFLAGS_prom_init.o += -DDISABLE_BRANCH_PROFILING > > CFLAGS_prom_init.o += -ffreestanding > > > > diff --git a/arch/powerpc/platforms/powermac/Makefile b/arch/powerpc/platforms/powermac/Makefile > > index f4247ade71ca..cf85f0662d0d 100644 > > --- a/arch/powerpc/platforms/powermac/Makefile > > +++ b/arch/powerpc/platforms/powermac/Makefile > > @@ -1,6 +1,6 @@ > > # SPDX-License-Identifier: GPL-2.0 > > CFLAGS_bootx_init.o += -fPIC > > -CFLAGS_bootx_init.o += $(call cc-option, -fno-stack-protector) > > +CFLAGS_bootx_init.o += -fno-stack-protector > > > > KASAN_SANITIZE_bootx_init.o := n > > > > diff --git a/arch/sparc/vdso/Makefile b/arch/sparc/vdso/Makefile > > index 708cb6304c2d..f44355e46f31 100644 > > --- a/arch/sparc/vdso/Makefile > > +++ b/arch/sparc/vdso/Makefile > > @@ -54,7 +54,7 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE > > # optimize sibling calls. > > # > > CFL := $(PROFILING) -mcmodel=medlow -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 > > > > @@ -93,7 +93,7 @@ KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32)) > > KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32)) > > KBUILD_CFLAGS_32 := $(filter-out $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS_32)) > > KBUILD_CFLAGS_32 += -m32 -msoft-float -fpic > > -KBUILD_CFLAGS_32 += $(call cc-option, -fno-stack-protector) > > +KBUILD_CFLAGS_32 += -fno-stack-protector > > KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls) > > KBUILD_CFLAGS_32 += -fno-omit-frame-pointer > > KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING > > diff --git a/arch/um/Makefile b/arch/um/Makefile > > index 3f27aa3ec0a6..1cea46ff9bb7 100644 > > --- a/arch/um/Makefile > > +++ b/arch/um/Makefile > > @@ -121,8 +121,7 @@ LINK-$(CONFIG_LD_SCRIPT_STATIC) += -static > > LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib $(call cc-option, -no-pie) > > > > CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,) \ > > - $(call cc-option, -fno-stack-protector,) \ > > - $(call cc-option, -fno-stack-protector-all,) > > + -fno-stack-protector $(call cc-option, -fno-stack-protector-all) > > Just curious, looks like we could do the same for > `-fno-stack-protector-all`, here or tree-wide, right? Wait, what > compiler recognizes -fno-stack-protector-all? > https://godbolt.org/z/QFQKE_ -fstack-protector -fstack-protector-strong -fstack-protector-all are supported. But, -fno-stack-protector-strong -fno-stack-protector-all are unsupported. Perheps, -fno-stack-protector is enough to disable all variants of stack-protector. -- Best Regards Masahiro Yamada
