Commit b250e6d1 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'kbuild-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild 

Pull Kbuild updates from Masahiro Yamada:

 - Add -s option (strict mode) to merge_config.sh to make it fail when
   any symbol is redefined.

 - Show a warning if a different compiler is used for building external
   modules.

 - Infer --target from ARCH for CC=clang to let you cross-compile the
   kernel without CROSS_COMPILE.

 - Make the integrated assembler default (LLVM_IAS=1) for CC=clang.

 - Add <linux/stdarg.h> to the kernel source instead of borrowing
   <stdarg.h> from the compiler.

 - Add Nick Desaulniers as a Kbuild reviewer.

 - Drop stale cc-option tests.

 - Fix the combination of CONFIG_TRIM_UNUSED_KSYMS and CONFIG_LTO_CLANG
   to handle symbols in inline assembly.

 - Show a warning if 'FORCE' is missing for if_changed rules.

 - Various cleanups

* tag 'kbuild-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (39 commits)
  kbuild: redo fake deps at include/ksym/*.h
  kbuild: clean up objtool_args slightly
  modpost: get the *.mod file path more simply
  checkkconfigsymbols.py: Fix the '--ignore' option
  kbuild: merge vmlinux_link() between ARCH=um and other architectures
  kbuild: do not remove 'linux' link in scripts/link-vmlinux.sh
  kbuild: merge vmlinux_link() between the ordinary link and Clang LTO
  kbuild: remove stale *.symversions
  kbuild: remove unused quiet_cmd_update_lto_symversions
  gen_compile_commands: extract compiler command from a series of commands
  x86: remove cc-option-yn test for -mtune=
  arc: replace cc-option-yn uses with cc-option
  s390: replace cc-option-yn uses with cc-option
  ia64: move core-y in arch/ia64/Makefile to arch/ia64/Kbuild
  sparc: move the install rule to arch/sparc/Makefile
  security: remove unneeded subdir-$(CONFIG_...)
  kbuild: sh: remove unused install script
  kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y
  kbuild: Switch to 'f' variants of integrated assembler flag
  kbuild: Shuffle blank line to improve comment meaning
  ...
parents 4e71add0 bc7cd2dd

Documentation/kbuild/llvm.rst

+22 −3
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ Cross Compiling 
A single Clang compiler binary will typically contain all supported backends,

which can help simplify cross compiling. ::



	ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make CC=clang

	make ARCH=arm64 CC=clang CROSS_COMPILE=aarch64-linux-gnu-



``CROSS_COMPILE`` is not used to prefix the Clang compiler binary, instead

``CROSS_COMPILE`` is used to set a command line flag: ``--target=<triple>``. For
@@ -60,8 +60,27 @@ They can be enabled individually. The full list of the parameters: :: 
	  OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump READELF=llvm-readelf \

	  HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar HOSTLD=ld.lld



Currently, the integrated assembler is disabled by default. You can pass

``LLVM_IAS=1`` to enable it.

The integrated assembler is enabled by default. You can pass ``LLVM_IAS=0`` to

disable it.



Omitting CROSS_COMPILE

----------------------



As explained above, ``CROSS_COMPILE`` is used to set ``--target=<triple>``.



If ``CROSS_COMPILE`` is not specified, the ``--target=<triple>`` is inferred

from ``ARCH``.



That means if you use only LLVM tools, ``CROSS_COMPILE`` becomes unnecessary.



For example, to cross-compile the arm64 kernel::



	make ARCH=arm64 LLVM=1



If ``LLVM_IAS=0`` is specified, ``CROSS_COMPILE`` is also used to derive

``--prefix=<path>`` to search for the GNU assembler and linker. ::



	make ARCH=arm64 LLVM=1 LLVM_IAS=0 CROSS_COMPILE=aarch64-linux-gnu-



Supported Architectures

-----------------------

MAINTAINERS

+2 −0
Original line number Diff line number Diff line
@@ -4532,6 +4532,7 @@ B: https://github.com/ClangBuiltLinux/linux/issues 
C:	irc://irc.libera.chat/clangbuiltlinux

F:	Documentation/kbuild/llvm.rst

F:	include/linux/compiler-clang.h

F:	scripts/Makefile.clang

F:	scripts/clang-tools/

K:	\b(?i:clang|llvm)\b








@@ -10116,6 +10117,7 @@ F:	fs/autofs/







KERNEL BUILD + files below scripts/ (unless maintained elsewhere)









M:	Masahiro Yamada <masahiroy@kernel.org>









M:	Michal Marek <michal.lkml@markovi.net>









R:	Nick Desaulniers <ndesaulniers@google.com>









L:	linux-kbuild@vger.kernel.org









S:	Maintained









T:	git git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
































Makefile



+49
−41






























Original line number
Diff line number
Diff line







@@ -191,10 +191,9 @@ endif







ifneq ($(abs_srctree),$(abs_objtree))









# Look for make include files relative to root of kernel src









#









# This does not become effective immediately because MAKEFLAGS is re-parsed









# once after the Makefile is read. We need to invoke sub-make.









# --included-dir is added for backward compatibility, but you should not rely on









# it. Please add $(srctree)/ prefix to include Makefiles in the source tree.









MAKEFLAGS += --include-dir=$(abs_srctree)









need-sub-make := 1









endif



















ifneq ($(filter 3.%,$(MAKE_VERSION)),)








@@ -587,23 +586,10 @@ endif







# 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 = $(subst $(pound),,$(shell $(CC) --version 2>/dev/null | head -n 1))









CC_VERSION_TEXT = $(subst $(pound),,$(shell LC_ALL=C $(CC) --version 2>/dev/null | head -n 1))



















ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)









ifneq ($(CROSS_COMPILE),)









CLANG_FLAGS	+= --target=$(notdir $(CROSS_COMPILE:%-=%))









endif









ifeq ($(LLVM_IAS),1)









CLANG_FLAGS	+= -integrated-as









else









CLANG_FLAGS	+= -no-integrated-as









GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))









CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))









endif









CLANG_FLAGS	+= -Werror=unknown-warning-option









KBUILD_CFLAGS	+= $(CLANG_FLAGS)









KBUILD_AFLAGS	+= $(CLANG_FLAGS)









export CLANG_FLAGS









include $(srctree)/scripts/Makefile.clang









endif



















# Include this also for config targets because some architectures need








@@ -688,9 +674,10 @@ endif # KBUILD_EXTMOD







# 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,)









CFLAGS_GCOV	:= -fprofile-arcs -ftest-coverage









ifdef CONFIG_CC_IS_GCC









CFLAGS_GCOV	+= -fno-tree-loop-im









endif









export CFLAGS_GCOV



















# The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.








@@ -698,12 +685,14 @@ ifdef CONFIG_FUNCTION_TRACER







  CC_FLAGS_FTRACE := -pg









endif



















RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register









RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register









RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk









RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline









RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))









RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))









ifdef CONFIG_CC_IS_GCC









RETPOLINE_CFLAGS	:= $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)









RETPOLINE_VDSO_CFLAGS	:= $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register)









endif









ifdef CONFIG_CC_IS_CLANG









RETPOLINE_CFLAGS	:= -mretpoline-external-thunk









RETPOLINE_VDSO_CFLAGS	:= -mretpoline









endif









export RETPOLINE_CFLAGS









export RETPOLINE_VDSO_CFLAGS


















@@ -756,7 +745,7 @@ include/config/auto.conf:







endif # may-sync-config









endif # need-config



















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









KBUILD_CFLAGS	+= -fno-delete-null-pointer-checks









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









KBUILD_CFLAGS	+= $(call cc-disable-warning, format-truncation)









KBUILD_CFLAGS	+= $(call cc-disable-warning, format-overflow)








@@ -771,17 +760,19 @@ KBUILD_CFLAGS += -Os







endif



















# Tell gcc to never replace conditional load with a non-conditional one









ifdef CONFIG_CC_IS_GCC









# gcc-10 renamed --param=allow-store-data-races=0 to









# -fno-allow-store-data-races.









KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)









KBUILD_CFLAGS	+= $(call cc-option,-fno-allow-store-data-races)









endif



















ifdef CONFIG_READABLE_ASM









# Disable optimizations that make assembler listings hard to read.









# reorder blocks reorders the control in the function









# ipa clone creates specialized cloned functions









# partial inlining inlines only parts of functions









KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \









                 $(call cc-option,-fno-ipa-cp-clone,) \









                 $(call cc-option,-fno-partial-inlining)









KBUILD_CFLAGS += -fno-reorder-blocks -fno-ipa-cp-clone -fno-partial-inlining









endif



















ifneq ($(CONFIG_FRAME_WARN),0)








@@ -796,7 +787,7 @@ KBUILD_CFLAGS += $(stackp-flags-y)

















ifdef CONFIG_CC_IS_CLANG









KBUILD_CPPFLAGS += -Qunused-arguments









KBUILD_CFLAGS += -Wno-format-invalid-specifier









# The kernel builds with '-std=gnu89' so use of GNU extensions is acceptable.









KBUILD_CFLAGS += -Wno-gnu









# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the









# source of a reference will be _MergedGlobals and not on of the whitelisted names.








@@ -813,8 +804,8 @@ endif







# These warnings generated too much noise in a regular build.









# Use make W=1 to enable them (see scripts/Makefile.extrawarn)









KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)



















KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)



















ifdef CONFIG_FRAME_POINTER









KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls









else








@@ -867,7 +858,7 @@ else







DEBUG_CFLAGS	+= -g









endif



















ifneq ($(LLVM_IAS),1)









ifndef CONFIG_AS_IS_LLVM









KBUILD_AFLAGS	+= -Wa,-gdwarf-2









endif


















@@ -878,8 +869,10 @@ DEBUG_CFLAGS	+= -gdwarf-$(dwarf-version-y)







endif



















ifdef CONFIG_DEBUG_INFO_REDUCED









DEBUG_CFLAGS	+= $(call cc-option, -femit-struct-debug-baseonly) \









		   $(call cc-option,-fno-var-tracking)









DEBUG_CFLAGS	+= -fno-var-tracking









ifdef CONFIG_CC_IS_GCC









DEBUG_CFLAGS	+= -femit-struct-debug-baseonly









endif









endif



















ifdef CONFIG_DEBUG_INFO_COMPRESSED








@@ -913,6 +906,7 @@ ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT







  endif









endif









ifdef CONFIG_HAVE_FENTRY









  # s390-linux-gnu-gcc did not support -mfentry until gcc-9.









  ifeq ($(call cc-option-yn, -mfentry),y)









    CC_FLAGS_FTRACE	+= -mfentry









    CC_FLAGS_USING	+= -DCC_USING_FENTRY








@@ -925,7 +919,7 @@ endif

















# We trigger additional mismatches with less inlining









ifdef CONFIG_DEBUG_SECTION_MISMATCH









KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)









KBUILD_CFLAGS += -fno-inline-functions-called-once









endif



















ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION








@@ -1004,14 +998,16 @@ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)

















# We'll want to enable this eventually, but it's not going away for 5.7 at least









KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)









KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds)









KBUILD_CFLAGS += -Wno-array-bounds









KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)



















# Another good warning that we'll want to enable eventually









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



















# Enabled with W=2, disabled by default as noisy









KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)









ifdef CONFIG_CC_IS_GCC









KBUILD_CFLAGS += -Wno-maybe-uninitialized









endif



















# disable invalid "can't wrap" optimizations for signed / pointers









KBUILD_CFLAGS	+= -fno-strict-overflow








@@ -1020,7 +1016,9 @@ KBUILD_CFLAGS	+= -fno-strict-overflow







KBUILD_CFLAGS  += -fno-stack-check



















# conserve stack if available









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









ifdef CONFIG_CC_IS_GCC









KBUILD_CFLAGS   += -fconserve-stack









endif



















# Prohibit date/time macros, which would make the build non-deterministic









KBUILD_CFLAGS   += -Werror=date-time








@@ -1750,6 +1748,16 @@ clean-dirs := $(KBUILD_EXTMOD)







clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps \









	$(KBUILD_EXTMOD)/compile_commands.json $(KBUILD_EXTMOD)/.thinlto-cache



















PHONY += prepare









# now expand this into a simple variable to reduce the cost of shell evaluations









prepare: CC_VERSION_TEXT := $(CC_VERSION_TEXT)









prepare:









	@if [ "$(CC_VERSION_TEXT)" != $(CONFIG_CC_VERSION_TEXT) ]; then \









		echo >&2 "warning: the compiler differs from the one used to build the kernel"; \









		echo >&2 "  The kernel was built by: "$(CONFIG_CC_VERSION_TEXT); \









		echo >&2 "  You are using:           $(CC_VERSION_TEXT)"; \









	fi



















PHONY += help









help:









	@echo  '  Building external modules.'








@@ -1761,7 +1769,7 @@ help:







	@echo  ''



















# no-op for external module builds









PHONY += prepare modules_prepare









PHONY += modules_prepare



















endif # KBUILD_EXTMOD










































arch/arc/Makefile



+1
−2






























Original line number
Diff line number
Diff line







@@ -18,8 +18,7 @@ ifeq ($(CONFIG_ARC_TUNE_MCPU),"")







cflags-y				+= $(tune-mcpu-def-y)









else









tune-mcpu				:= $(shell echo $(CONFIG_ARC_TUNE_MCPU))









tune-mcpu-ok 				:= $(call cc-option-yn, $(tune-mcpu))









ifeq ($(tune-mcpu-ok),y)









ifneq ($(call cc-option,$(tune-mcpu)),)









cflags-y				+= $(tune-mcpu)









else









# The flag provided by 'CONFIG_ARC_TUNE_MCPU' option isn't known by this compiler
































arch/arm/kernel/process.c



+0
−2






























Original line number
Diff line number
Diff line







@@ -5,8 +5,6 @@







 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.









 *  Original Copyright (C) 1995  Linus Torvalds









 */









#include <stdarg.h>



















#include <linux/export.h>









#include <linux/sched.h>









#include <linux/sched/debug.h>