Commit be779f03 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'kbuild-v4.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild 

Pull more Kbuild updates from Masahiro Yamada:

 - fix some bugs introduced by the recent Kconfig syntax extension

 - add some symbols about compiler information in Kconfig, such as
   CC_IS_GCC, CC_IS_CLANG, GCC_VERSION, etc.

 - test compiler capability for the stack protector in Kconfig, and
   clean-up Makefile

 - test compiler capability for GCC-plugins in Kconfig, and clean-up
   Makefile

 - allow to enable GCC-plugins for COMPILE_TEST

 - test compiler capability for KCOV in Kconfig and correct dependency

 - remove auto-detect mode of the GCOV format, which is now more nicely
   handled in Kconfig

 - test compiler capability for mprofile-kernel on PowerPC, and clean-up
   Makefile

 - misc cleanups

* tag 'kbuild-v4.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  linux/linkage.h: replace VMLINUX_SYMBOL_STR() with __stringify()
  kconfig: fix localmodconfig
  sh: remove no-op macro VMLINUX_SYMBOL()
  powerpc/kbuild: move -mprofile-kernel check to Kconfig
  Documentation: kconfig: add recommended way to describe compiler support
  gcc-plugins: disable GCC_PLUGIN_STRUCTLEAK_BYREF_ALL for COMPILE_TEST
  gcc-plugins: allow to enable GCC_PLUGINS for COMPILE_TEST
  gcc-plugins: test plugin support in Kconfig and clean up Makefile
  gcc-plugins: move GCC version check for PowerPC to Kconfig
  kcov: test compiler capability in Kconfig and correct dependency
  gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT
  arm64: move GCC version check for ARCH_SUPPORTS_INT128 to Kconfig
  kconfig: add CC_IS_CLANG and CLANG_VERSION
  kconfig: add CC_IS_GCC and GCC_VERSION
  stack-protector: test compiler capability in Kconfig and drop AUTO mode
  kbuild: fix endless syncconfig in case arch Makefile sets CROSS_COMPILE
parents d290ef93 00979ce4

Documentation/kbuild/kconfig-language.txt

+18 −0
Original line number Diff line number Diff line
@@ -473,6 +473,24 @@ config option to 'y' no matter the dependencies. 
The dependencies are moved to the symbol GENERIC_IOMAP and we avoid the

situation where select forces a symbol equals to 'y'.



Adding features that need compiler support

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



There are several features that need compiler support. The recommended way

to describe the dependency on the compiler feature is to use "depends on"

followed by a test macro.



config CC_STACKPROTECTOR

	bool "Stack Protector buffer overflow detection"

	depends on $(cc-option,-fstack-protector)

	...



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)



Build as module only

~~~~~~~~~~~~~~~~~~~~

To restrict a component build to module-only, qualify its config symbol

Makefile

+36 −111
Original line number Diff line number Diff line
@@ -442,8 +442,6 @@ export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE 
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL

export KBUILD_ARFLAGS



export CC_VERSION_TEXT := $(shell $(CC) --version | head -n 1)



# When compiling out-of-tree modules, put MODVERDIR in the module

# tree rather than in the kernel tree. The kernel tree might

# even be read-only.
@@ -514,6 +512,12 @@ ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/cc-can-link.sh $(CC)), y) 
  export CC_CAN_LINK

endif



# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.

# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.

# CC_VERSION_TEXT is referenced from Kconfig (so it needs export),

# and from include/config/auto.conf.cmd to detect the compiler upgrade.

CC_VERSION_TEXT = $(shell $(CC) --version | head -n 1)



ifeq ($(config-targets),1)

# ===========================================================================

# *config targets only - make sure prerequisites are updated, and descend
@@ -523,7 +527,7 @@ ifeq ($(config-targets),1) 
# KBUILD_DEFCONFIG may point out an alternative default configuration

# used for 'make defconfig'

include arch/$(SRCARCH)/Makefile

export KBUILD_DEFCONFIG KBUILD_KCONFIG

export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT



config: scripts_basic outputmakefile FORCE

	$(Q)$(MAKE) $(build)=scripts/kconfig $@
@@ -585,12 +589,32 @@ virt-y := virt/ 
endif # KBUILD_EXTMOD



ifeq ($(dot-config),1)

# Read in config

-include include/config/auto.conf

endif



# The all: target is the default when no target is given on the

# command line.

# This allow a user to issue only 'make' to build a kernel including modules

# Defaults to vmlinux, but the arch makefile usually adds further targets

all: vmlinux



CFLAGS_GCOV	:= -fprofile-arcs -ftest-coverage \

	$(call cc-option,-fno-tree-loop-im) \

	$(call cc-disable-warning,maybe-uninitialized,)

export CFLAGS_GCOV



# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default

# values of the respective KBUILD_* variables

ARCH_CPPFLAGS :=

ARCH_AFLAGS :=

ARCH_CFLAGS :=

include arch/$(SRCARCH)/Makefile



ifeq ($(dot-config),1)

ifeq ($(KBUILD_EXTMOD),)

# Read in dependencies to all Kconfig* files, make sure to run

# oldconfig if changes are detected.

# Read in dependencies to all Kconfig* files, make sure to run syncconfig if

# changes are detected. This should be included after arch/$(SRCARCH)/Makefile

# because some architectures define CROSS_COMPILE there.

-include include/config/auto.conf.cmd



# To avoid any implicit rule to kick in, define an empty command
@@ -622,24 +646,6 @@ else 
include/config/auto.conf: ;

endif # $(dot-config)



# The all: target is the default when no target is given on the

# command line.

# This allow a user to issue only 'make' to build a kernel including modules

# Defaults to vmlinux, but the arch makefile usually adds further targets

all: vmlinux



CFLAGS_GCOV	:= -fprofile-arcs -ftest-coverage \

	$(call cc-option,-fno-tree-loop-im) \

	$(call cc-disable-warning,maybe-uninitialized,)

export CFLAGS_GCOV CFLAGS_KCOV



# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default

# values of the respective KBUILD_* variables

ARCH_CPPFLAGS :=

ARCH_AFLAGS :=

ARCH_CFLAGS :=

include arch/$(SRCARCH)/Makefile



KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)

KBUILD_CFLAGS	+= $(call cc-disable-warning,frame-address,)

KBUILD_CFLAGS	+= $(call cc-disable-warning, format-truncation)
@@ -680,55 +686,11 @@ ifneq ($(CONFIG_FRAME_WARN),0) 
KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})

endif



# This selects the stack protector compiler flag. Testing it is delayed

# until after .config has been reprocessed, in the prepare-compiler-check

# target.

ifdef CONFIG_CC_STACKPROTECTOR_AUTO

  stackp-flag := $(call cc-option,-fstack-protector-strong,$(call cc-option,-fstack-protector))

  stackp-name := AUTO

else

ifdef CONFIG_CC_STACKPROTECTOR_REGULAR

  stackp-flag := -fstack-protector

  stackp-name := REGULAR

else

ifdef CONFIG_CC_STACKPROTECTOR_STRONG

  stackp-flag := -fstack-protector-strong

  stackp-name := STRONG

else

  # If either there is no stack protector for this architecture or

  # CONFIG_CC_STACKPROTECTOR_NONE is selected, we're done, and $(stackp-name)

  # is empty, skipping all remaining stack protector tests.

  #

  # Force off for distro compilers that enable stack protector by default.

  KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)

endif

endif

endif

# Find arch-specific stack protector compiler sanity-checking script.

ifdef stackp-name

ifneq ($(stackp-flag),)

  stackp-path := $(srctree)/scripts/gcc-$(SRCARCH)_$(BITS)-has-stack-protector.sh

  stackp-check := $(wildcard $(stackp-path))

  # If the wildcard test matches a test script, run it to check functionality.

  ifdef stackp-check

    ifneq ($(shell $(CONFIG_SHELL) $(stackp-check) $(CC) $(KBUILD_CPPFLAGS) $(biarch)),y)

      stackp-broken := y

    endif

  endif

  ifndef stackp-broken

    # If the stack protector is functional, enable code that depends on it.

    KBUILD_CPPFLAGS += -DCONFIG_CC_STACKPROTECTOR

    # Either we've already detected the flag (for AUTO) or we'll fail the

    # build in the prepare-compiler-check rule (for specific flag).

    KBUILD_CFLAGS += $(stackp-flag)

  else

    # We have to make sure stack protector is unconditionally disabled if

    # the compiler is broken (in case we're going to continue the build in

    # AUTO mode).

    KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)

  endif

endif

endif

stackp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector

stackp-flags-$(CONFIG_CC_STACKPROTECTOR)          := -fstack-protector

stackp-flags-$(CONFIG_CC_STACKPROTECTOR_STRONG)   := -fstack-protector-strong



KBUILD_CFLAGS += $(stackp-flags-y)



ifeq ($(cc-name),clang)

KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
@@ -1112,7 +1074,7 @@ endif 
# prepare2 creates a makefile if using a separate output directory.

# From this point forward, .config has been reprocessed, so any rules

# that need to depend on updated CONFIG_* values can be checked here.

prepare2: prepare3 prepare-compiler-check outputmakefile asm-generic

prepare2: prepare3 outputmakefile asm-generic



prepare1: prepare2 $(version_h) $(autoksyms_h) include/generated/utsrelease.h \

                   include/config/auto.conf
@@ -1138,43 +1100,6 @@ uapi-asm-generic: 
PHONY += prepare-objtool

prepare-objtool: $(objtool_target)



# Check for CONFIG flags that require compiler support. Abort the build

# after .config has been processed, but before the kernel build starts.

#

# For security-sensitive CONFIG options, we don't want to fallback and/or

# silently change which compiler flags will be used, since that leads to

# producing kernels with different security feature characteristics

# depending on the compiler used. (For example, "But I selected

# CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!")

PHONY += prepare-compiler-check

prepare-compiler-check: FORCE

# Make sure compiler supports requested stack protector flag.

ifdef stackp-name

  # Warn about CONFIG_CC_STACKPROTECTOR_AUTO having found no option.

  ifeq ($(stackp-flag),)

	@echo CONFIG_CC_STACKPROTECTOR_$(stackp-name): \

		  Compiler does not support any known stack-protector >&2

  else

  # Fail if specifically requested stack protector is missing.

  ifeq ($(call cc-option, $(stackp-flag)),)

	@echo Cannot use CONFIG_CC_STACKPROTECTOR_$(stackp-name): \

		  $(stackp-flag) not supported by compiler >&2 && exit 1

  endif

  endif

endif

# Make sure compiler does not have buggy stack-protector support. If a

# specific stack-protector was requested, fail the build, otherwise warn.

ifdef stackp-broken

  ifeq ($(stackp-name),AUTO)

	@echo CONFIG_CC_STACKPROTECTOR_$(stackp-name): \

                  $(stackp-flag) available but compiler is broken: disabling >&2

  else

	@echo Cannot use CONFIG_CC_STACKPROTECTOR_$(stackp-name): \

                  $(stackp-flag) available but compiler is broken >&2 && exit 1

  endif

endif

	@:



# Generate some files

# ---------------------------------------------------------------------------

arch/Kconfig

+25 −25
Original line number Diff line number Diff line
@@ -405,6 +405,15 @@ config SECCOMP_FILTER 


	  See Documentation/prctl/seccomp_filter.txt for details.



preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))



config PLUGIN_HOSTCC

	string

	default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")"

	help

	  Host compiler used to build GCC plugins.  This can be $(HOSTCXX),

	  $(HOSTCC), or a null string if GCC plugin is unsupported.



config HAVE_GCC_PLUGINS

	bool

	help
@@ -414,7 +423,7 @@ config HAVE_GCC_PLUGINS 
menuconfig GCC_PLUGINS

	bool "GCC plugins"

	depends on HAVE_GCC_PLUGINS

	depends on !COMPILE_TEST

	depends on PLUGIN_HOSTCC != ""

	help

	  GCC plugins are loadable modules that provide extra features to the

	  compiler. They are useful for runtime instrumentation and static analysis.
@@ -424,7 +433,7 @@ menuconfig GCC_PLUGINS 
config GCC_PLUGIN_CYC_COMPLEXITY

	bool "Compute the cyclomatic complexity of a function" if EXPERT

	depends on GCC_PLUGINS

	depends on !COMPILE_TEST

	depends on !COMPILE_TEST	# too noisy

	help

	  The complexity M of a function's control flow graph is defined as:

	   M = E - N + 2P
@@ -484,6 +493,7 @@ config GCC_PLUGIN_STRUCTLEAK 
config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL

	bool "Force initialize all struct type variables passed by reference"

	depends on GCC_PLUGIN_STRUCTLEAK

	depends on !COMPILE_TEST

	help

	  Zero initialize any struct type local variable that may be passed by

	  reference without having been initialized.
@@ -491,7 +501,7 @@ config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL 
config GCC_PLUGIN_STRUCTLEAK_VERBOSE

	bool "Report forcefully initialized variables"

	depends on GCC_PLUGIN_STRUCTLEAK

	depends on !COMPILE_TEST

	depends on !COMPILE_TEST	# too noisy

	help

	  This option will cause a warning to be printed each time the

	  structleak plugin finds a variable it thinks needs to be
@@ -531,7 +541,7 @@ config GCC_PLUGIN_RANDSTRUCT 
config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE

	bool "Use cacheline-aware structure randomization"

	depends on GCC_PLUGIN_RANDSTRUCT

	depends on !COMPILE_TEST

	depends on !COMPILE_TEST	# do not reduce test coverage

	help

	  If you say Y here, the RANDSTRUCT randomization will make a

	  best effort at restricting randomization to cacheline-sized
@@ -543,13 +553,16 @@ config HAVE_CC_STACKPROTECTOR 
	bool

	help

	  An arch should select this symbol if:

	  - its compiler supports the -fstack-protector option

	  - it has implemented a stack canary (e.g. __stack_chk_guard)



choice

	prompt "Stack Protector buffer overflow detection"

config CC_HAS_STACKPROTECTOR_NONE

	def_bool $(cc-option,-fno-stack-protector)



config CC_STACKPROTECTOR

	bool "Stack Protector buffer overflow detection"

	depends on HAVE_CC_STACKPROTECTOR

	default CC_STACKPROTECTOR_AUTO

	depends on $(cc-option,-fstack-protector)

	default y

	help

	  This option turns on the "stack-protector" GCC feature. This

	  feature puts, at the beginning of functions, a canary value on
@@ -559,14 +572,6 @@ choice 
	  overwrite the canary, which gets detected and the attack is then

	  neutralized via a kernel panic.



config CC_STACKPROTECTOR_NONE

	bool "None"

	help

	  Disable "stack-protector" GCC feature.



config CC_STACKPROTECTOR_REGULAR

	bool "Regular"

	help

	  Functions will have the stack-protector canary logic added if they

	  have an 8-byte or larger character array on the stack.
@@ -578,7 +583,10 @@ config CC_STACKPROTECTOR_REGULAR 
	  by about 0.3%.



config CC_STACKPROTECTOR_STRONG

	bool "Strong"

	bool "Strong Stack Protector"

	depends on CC_STACKPROTECTOR

	depends on $(cc-option,-fstack-protector-strong)

	default y

	help

	  Functions will have the stack-protector canary logic added in any

	  of the following conditions:
@@ -596,14 +604,6 @@ config CC_STACKPROTECTOR_STRONG 
	  about 20% of all kernel functions, which increases the kernel code

	  size by about 2%.



config CC_STACKPROTECTOR_AUTO

	bool "Automatic"

	help

	  If the compiler supports it, the best available stack-protector

	  option will be chosen.



endchoice



config HAVE_ARCH_WITHIN_STACK_FRAMES

	bool

	help

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ config ARM64 
	select ARCH_USE_QUEUED_RWLOCKS

	select ARCH_SUPPORTS_MEMORY_FAILURE

	select ARCH_SUPPORTS_ATOMIC_RMW

	select ARCH_SUPPORTS_INT128 if GCC_VERSION >= 50000 || CC_IS_CLANG

	select ARCH_SUPPORTS_NUMA_BALANCING

	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION

	select ARCH_WANT_FRAME_POINTERS

arch/arm64/Makefile

+0 −6
Original line number Diff line number Diff line
@@ -56,12 +56,6 @@ KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) 
KBUILD_CFLAGS	+= $(call cc-option,-mabi=lp64)

KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)



ifeq ($(cc-name),clang)

KBUILD_CFLAGS	+= -DCONFIG_ARCH_SUPPORTS_INT128

else

KBUILD_CFLAGS	+= $(call cc-ifversion, -ge, 0500, -DCONFIG_ARCH_SUPPORTS_INT128)

endif



ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)

KBUILD_CPPFLAGS	+= -mbig-endian

CHECKFLAGS	+= -D__AARCH64EB__

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