From 893ab00439a45513cae55781fc8e3b7108ee1cda Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sat, 27 Jun 2020 03:59:12 +0900 Subject: 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 Reviewed-by: Kees Cook Acked-by: Ard Biesheuvel Reviewed-by: Nick Desaulniers --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index fe0164a654c7..ea283c9bbaa8 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 -- cgit v1.2.3 From 3ec8a5b33deacdeca4bef24fb15498a975e875ba Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 2 Jul 2020 04:29:36 +0900 Subject: kbuild: do not export LDFLAGS_vmlinux When you clean the build tree for ARCH=arm, you may see the following error message from 'nm' command: $ make -j24 ARCH=arm clean CLEAN arch/arm/crypto CLEAN arch/arm/kernel CLEAN arch/arm/mach-at91 CLEAN arch/arm/mach-omap2 CLEAN arch/arm/vdso CLEAN certs CLEAN lib CLEAN usr CLEAN net/wireless CLEAN drivers/firmware/efi/libstub nm: 'arch/arm/boot/compressed/../../../../vmlinux': No such file /bin/sh: 1: arithmetic expression: expecting primary: " " CLEAN arch/arm/boot/compressed CLEAN drivers/scsi CLEAN drivers/tty/vt CLEAN arch/arm/boot CLEAN vmlinux.symvers modules.builtin modules.builtin.modinfo Even if you rerun the same command, the error message will not be shown despite vmlinux is already gone. To reproduce it, the parallel option -j is needed. Single thread cleaning always executes 'archclean', 'vmlinuxclean' in this order, so vmlinux still exists when arch/arm/boot/compressed/ is cleaned. Looking at arch/arm/boot/compressed/Makefile does not help understand the reason of the error message. Both KBSS_SZ and LDFLAGS_vmlinux are assigned with '=' operator, hence, they are not expanded unless used. Obviously, 'make clean' does not use them. In fact, the root cause exists in the top Makefile: export LDFLAGS_vmlinux Since LDFLAGS_vmlinux is an exported variable, LDFLAGS_vmlinux in arch/arm/boot/compressed/Makefile is expanded when scripts/Makefile.clean has a command to execute. This is why the error message shows up only when there exist build artifacts in arch/arm/boot/compressed/. Adding 'unexport LDFLAGS_vmlinux' to arch/arm/boot/compressed/Makefile will fix it as far as ARCH=arm is concerned, but I think the proper fix is to get rid of 'export LDFLAGS_vmlinux' from the top Makefile. LDFLAGS_vmlinux in the top Makefile contains linker flags for the top vmlinux. LDFLAGS_vmlinux in arch/arm/boot/compressed/Makefile is for arch/arm/boot/compressed/vmlinux. They just happen to have the same variable name, but are used for different purposes. Stop shadowing LDFLAGS_vmlinux. This commit passes LDFLAGS_vmlinux to scripts/link-vmlinux.sh via a command line parameter instead of via an environment variable. LD and KBUILD_LDFLAGS are exported, but I did the same for consistency. Anyway, they must be included in cmd_link-vmlinux to allow if_changed to detect the changes in LD or KBUILD_LDFLAGS. The following Makefiles are not affected: arch/arm/boot/compressed/Makefile arch/h8300/boot/compressed/Makefile arch/nios2/boot/compressed/Makefile arch/parisc/boot/compressed/Makefile arch/s390/boot/compressed/Makefile arch/sh/boot/compressed/Makefile arch/sh/boot/romimage/Makefile arch/x86/boot/compressed/Makefile They use ':=' or '=' to clear the LDFLAGS_vmlinux inherited from the top Makefile. We need to take a closer look at the impact to unicore32 and xtensa. arch/unicore32/boot/compressed/Makefile only uses '+=' operator for LDFLAGS_vmlinux. So, the decompressor previously inherited the linker flags from the top Makefile. However, commit 70fac51feaf2 ("unicore32 additional architecture files: boot process") was merged before commit 1f2bfbd00e46 ("kbuild: link of vmlinux moved to a script"). So, I rather consider this is a bug fix of 1f2bfbd00e46. arch/xtensa/boot/boot-elf/Makefile is also affected, but this is also considered a fix for the same reason. It did not inherit LDFLAGS_vmlinux when commit 4bedea945451 ("[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 2") was merged. I deleted $(LDFLAGS_vmlinux), which is now empty. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers --- Makefile | 3 +-- arch/xtensa/boot/boot-elf/Makefile | 2 +- scripts/link-vmlinux.sh | 4 ++++ 3 files changed, 6 insertions(+), 3 deletions(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index ea283c9bbaa8..ebf4d3ce492c 100644 --- a/Makefile +++ b/Makefile @@ -1100,7 +1100,6 @@ KBUILD_VMLINUX_OBJS += $(patsubst %/,%/built-in.a, $(drivers-y)) export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds -export LDFLAGS_vmlinux # used by scripts/Makefile.package export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) LICENSES arch include scripts tools) @@ -1132,7 +1131,7 @@ ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink) # Final link of vmlinux with optional arch pass after final link cmd_link-vmlinux = \ - $(CONFIG_SHELL) $< $(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_vmlinux) ; \ + $(CONFIG_SHELL) $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \ $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE diff --git a/arch/xtensa/boot/boot-elf/Makefile b/arch/xtensa/boot/boot-elf/Makefile index 12ae1e91cb75..a62a25506536 100644 --- a/arch/xtensa/boot/boot-elf/Makefile +++ b/arch/xtensa/boot/boot-elf/Makefile @@ -25,7 +25,7 @@ $(obj)/Image.o: vmlinux.bin $(OBJS) $(OBJS) $@ $(obj)/../Image.elf: $(obj)/Image.o $(obj)/boot.lds - $(Q)$(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_vmlinux) \ + $(Q)$(LD) $(KBUILD_LDFLAGS) \ -T $(obj)/boot.lds \ --build-id=none \ -o $@ $(obj)/Image.o diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 92dd745906f4..68e7de2dbe90 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -30,6 +30,10 @@ # Error out on error set -e +LD="$1" +KBUILD_LDFLAGS="$2" +LDFLAGS_vmlinux="$3" + # Nice output in kbuild format # Will be supressed by "make -s" info() -- cgit v1.2.3 From e0fe0bbe57b8d708a18756be5bc289bdaf78d2a8 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 2 Aug 2020 00:00:49 +0900 Subject: kbuild: include scripts/Makefile.* only when relevant CONFIG is enabled Currently, the top Makefile includes all of scripts/Makefile. even if the associated CONFIG option is disabled. Do not include unneeded Makefiles in order to slightly optimize the parse stage. Include $(include-y), and ignore $(include-). Signed-off-by: Masahiro Yamada --- Makefile | 16 +++++++++------- scripts/Makefile.kcov | 4 ---- scripts/Makefile.kcsan | 4 ---- scripts/Makefile.ubsan | 3 --- 4 files changed, 9 insertions(+), 18 deletions(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index ebf4d3ce492c..483456d5dd3e 100644 --- a/Makefile +++ b/Makefile @@ -745,9 +745,6 @@ endif KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races) -include scripts/Makefile.kcov -include scripts/Makefile.gcc-plugins - ifdef CONFIG_READABLE_ASM # Disable optimizations that make assembler listings hard to read. # reorder blocks reorders the control in the function @@ -948,10 +945,15 @@ ifdef CONFIG_RETPOLINE KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none) endif -include scripts/Makefile.kasan -include scripts/Makefile.extrawarn -include scripts/Makefile.ubsan -include scripts/Makefile.kcsan +# include additional Makefiles when needed +include-y := scripts/Makefile.extrawarn +include-$(CONFIG_KASAN) += scripts/Makefile.kasan +include-$(CONFIG_KCSAN) += scripts/Makefile.kcsan +include-$(CONFIG_UBSAN) += scripts/Makefile.ubsan +include-$(CONFIG_KCOV) += scripts/Makefile.kcov +include-$(CONFIG_GCC_PLUGINS) += scripts/Makefile.gcc-plugins + +include $(addprefix $(srctree)/, $(include-y)) # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments KBUILD_CPPFLAGS += $(KCPPFLAGS) diff --git a/scripts/Makefile.kcov b/scripts/Makefile.kcov index 52b113302443..67e8cfe3474b 100644 --- a/scripts/Makefile.kcov +++ b/scripts/Makefile.kcov @@ -1,10 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only -ifdef CONFIG_KCOV - kcov-flags-$(CONFIG_CC_HAS_SANCOV_TRACE_PC) += -fsanitize-coverage=trace-pc kcov-flags-$(CONFIG_KCOV_ENABLE_COMPARISONS) += -fsanitize-coverage=trace-cmp kcov-flags-$(CONFIG_GCC_PLUGIN_SANCOV) += -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so export CFLAGS_KCOV := $(kcov-flags-y) - -endif diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan index bd4da1af5953..2b0743e6566e 100644 --- a/scripts/Makefile.kcsan +++ b/scripts/Makefile.kcsan @@ -1,6 +1,4 @@ # SPDX-License-Identifier: GPL-2.0 -ifdef CONFIG_KCSAN - # GCC and Clang accept backend options differently. Do not wrap in cc-option, # because Clang accepts "--param" even if it is unused. ifdef CONFIG_CC_IS_CLANG @@ -15,5 +13,3 @@ CFLAGS_KCSAN := -fsanitize=thread \ $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \ $(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1)) \ $(call cc-param,tsan-distinguish-volatile=1) - -endif # CONFIG_KCSAN diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 5b15bc425ec9..27348029b2b8 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -1,6 +1,4 @@ # SPDX-License-Identifier: GPL-2.0 -ifdef CONFIG_UBSAN - ifdef CONFIG_UBSAN_ALIGNMENT CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment) endif @@ -26,4 +24,3 @@ endif # -fsanitize=* options makes GCC less smart than usual and # increase number of 'maybe-uninitialized false-positives CFLAGS_UBSAN += $(call cc-option, -Wno-maybe-uninitialized) -endif -- cgit v1.2.3 From 132305b3b474a85152302ceda4551384cce3904e Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 2 Aug 2020 00:00:50 +0900 Subject: kbuild: stop filtering out $(GCC_PLUGINS_CFLAGS) from cc-option base Commit d26e94149276 ("kbuild: no gcc-plugins during cc-option tests") was neeeded because scripts/Makefile.gcc-plugins was too early. This is unneeded by including scripts/Makefile.gcc-plugins last, and being careful to not add cc-option tests after it. Signed-off-by: Masahiro Yamada --- Makefile | 5 ++++- scripts/Kbuild.include | 10 +++------- 2 files changed, 7 insertions(+), 8 deletions(-) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 483456d5dd3e..712206381a27 100644 --- a/Makefile +++ b/Makefile @@ -506,7 +506,6 @@ KBUILD_CFLAGS_MODULE := -DMODULE KBUILD_LDFLAGS_MODULE := export KBUILD_LDS_MODULE := $(srctree)/scripts/module-common.lds KBUILD_LDFLAGS := -GCC_PLUGINS_CFLAGS := CLANG_FLAGS := export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC @@ -955,6 +954,10 @@ include-$(CONFIG_GCC_PLUGINS) += scripts/Makefile.gcc-plugins include $(addprefix $(srctree)/, $(include-y)) +# scripts/Makefile.gcc-plugins is intentionally included last. +# Do not add $(call cc-option,...) below this line. When you build the kernel +# from the clean source tree, the GCC plugins do not exist at this point. + # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments KBUILD_CPPFLAGS += $(KCPPFLAGS) KBUILD_AFLAGS += $(KAFLAGS) diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 9a15fbf66aa1..83a1637417e5 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -119,25 +119,21 @@ as-instr = $(call try-run,\ __cc-option = $(call try-run,\ $(1) -Werror $(2) $(3) -c -x c /dev/null -o "$$TMP",$(3),$(4)) -# Do not attempt to build with gcc plugins during cc-option tests. -# (And this uses delayed resolution so the flags will be up to date.) -CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) - # cc-option # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586) cc-option = $(call __cc-option, $(CC),\ - $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2)) + $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS),$(1),$(2)) # cc-option-yn # Usage: flag := $(call cc-option-yn,-march=winchip-c6) cc-option-yn = $(call try-run,\ - $(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n) + $(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n) # cc-disable-warning # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable) cc-disable-warning = $(call try-run,\ - $(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1))) + $(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1))) # cc-ifversion # Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) -- cgit v1.2.3