linux-stable/scripts/Makefile.build

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
# SPDX-License-Identifier: GPL-2.0
# ==========================================================================
# Building
# ==========================================================================
src := $(obj)
PHONY := $(obj)/
$(obj)/:
# Init all relevant variables used in kbuild files so
# 1) they have correct type
# 2) they do not inherit any value from the environment
obj-y :=
obj-m :=
lib-y :=
lib-m :=
always-y :=
always-m :=
targets :=
subdir-y :=
subdir-m :=
EXTRA_AFLAGS :=
EXTRA_CFLAGS :=
EXTRA_CPPFLAGS :=
EXTRA_LDFLAGS :=
asflags-y :=
ccflags-y :=
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
rustflags-y :=
cppflags-y :=
ldflags-y :=
subdir-asflags-y :=
subdir-ccflags-y :=
# Read auto.conf if it exists, otherwise ignore
-include include/config/auto.conf
include $(srctree)/scripts/Kbuild.include
include $(srctree)/scripts/Makefile.compiler
include $(kbuild-file)
include $(srctree)/scripts/Makefile.lib
# Do not include hostprogs rules unless needed.
# $(sort ...) is used here to remove duplicated words and excessive spaces.
hostprogs := $(sort $(hostprogs))
ifneq ($(hostprogs),)
include $(srctree)/scripts/Makefile.host
endif
kbuild: add infrastructure to build userspace programs Kbuild supports the infrastructure to build host programs, but there was no support to build userspace programs for the target architecture (i.e. the same architecture as the kernel). Sam Ravnborg worked on this in 2014 (https://lkml.org/lkml/2014/7/13/154), but it was not merged. One problem at that time was, there was no good way to know whether $(CC) can link standalone programs. In fact, pre-built kernel.org toolchains [1] are often used for building the kernel, but they do not provide libc. Now, we can handle this cleanly because the compiler capability is evaluated at the Kconfig time. If $(CC) cannot link standalone programs, the relevant options are hidden by 'depends on CC_CAN_LINK'. The implementation just mimics scripts/Makefile.host The userspace programs are compiled with the same flags as the host programs. In addition, it uses -m32 or -m64 if it is found in $(KBUILD_CFLAGS). This new syntax has two usecases. - Sample programs Several userspace programs under samples/ include UAPI headers installed in usr/include. Most of them were previously built for the host architecture just to use the 'hostprogs' syntax. However, 'make headers' always works for the target architecture. This caused the arch mismatch in cross-compiling. To fix this distortion, sample code should be built for the target architecture. - Bpfilter net/bpfilter/Makefile compiles bpfilter_umh as the user mode helper, and embeds it into the kernel. Currently, it overrides HOSTCC with CC to use the 'hostprogs' syntax. This hack should go away. [1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-04-29 03:45:14 +00:00
# Do not include userprogs rules unless needed.
# $(sort ...) is used here to remove duplicated words and excessive spaces.
kbuild: add infrastructure to build userspace programs Kbuild supports the infrastructure to build host programs, but there was no support to build userspace programs for the target architecture (i.e. the same architecture as the kernel). Sam Ravnborg worked on this in 2014 (https://lkml.org/lkml/2014/7/13/154), but it was not merged. One problem at that time was, there was no good way to know whether $(CC) can link standalone programs. In fact, pre-built kernel.org toolchains [1] are often used for building the kernel, but they do not provide libc. Now, we can handle this cleanly because the compiler capability is evaluated at the Kconfig time. If $(CC) cannot link standalone programs, the relevant options are hidden by 'depends on CC_CAN_LINK'. The implementation just mimics scripts/Makefile.host The userspace programs are compiled with the same flags as the host programs. In addition, it uses -m32 or -m64 if it is found in $(KBUILD_CFLAGS). This new syntax has two usecases. - Sample programs Several userspace programs under samples/ include UAPI headers installed in usr/include. Most of them were previously built for the host architecture just to use the 'hostprogs' syntax. However, 'make headers' always works for the target architecture. This caused the arch mismatch in cross-compiling. To fix this distortion, sample code should be built for the target architecture. - Bpfilter net/bpfilter/Makefile compiles bpfilter_umh as the user mode helper, and embeds it into the kernel. Currently, it overrides HOSTCC with CC to use the 'hostprogs' syntax. This hack should go away. [1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-04-29 03:45:14 +00:00
userprogs := $(sort $(userprogs))
ifneq ($(userprogs),)
include $(srctree)/scripts/Makefile.userprogs
kbuild: add infrastructure to build userspace programs Kbuild supports the infrastructure to build host programs, but there was no support to build userspace programs for the target architecture (i.e. the same architecture as the kernel). Sam Ravnborg worked on this in 2014 (https://lkml.org/lkml/2014/7/13/154), but it was not merged. One problem at that time was, there was no good way to know whether $(CC) can link standalone programs. In fact, pre-built kernel.org toolchains [1] are often used for building the kernel, but they do not provide libc. Now, we can handle this cleanly because the compiler capability is evaluated at the Kconfig time. If $(CC) cannot link standalone programs, the relevant options are hidden by 'depends on CC_CAN_LINK'. The implementation just mimics scripts/Makefile.host The userspace programs are compiled with the same flags as the host programs. In addition, it uses -m32 or -m64 if it is found in $(KBUILD_CFLAGS). This new syntax has two usecases. - Sample programs Several userspace programs under samples/ include UAPI headers installed in usr/include. Most of them were previously built for the host architecture just to use the 'hostprogs' syntax. However, 'make headers' always works for the target architecture. This caused the arch mismatch in cross-compiling. To fix this distortion, sample code should be built for the target architecture. - Bpfilter net/bpfilter/Makefile compiles bpfilter_umh as the user mode helper, and embeds it into the kernel. Currently, it overrides HOSTCC with CC to use the 'hostprogs' syntax. This hack should go away. [1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-04-29 03:45:14 +00:00
endif
ifndef obj
$(warning kbuild: Makefile.build is included improperly)
endif
kbuild: make single targets work more correctly Currently, the single target build directly descends into the directory of the target. For example, $ make foo/bar/baz.o ... directly descends into foo/bar/. On the other hand, the normal build usually descends one directory at a time, i.e. descends into foo/, and then foo/bar/. This difference causes some problems. [1] miss subdir-asflags-y, subdir-ccflags-y in upper Makefiles The options in subdir-{as,cc}flags-y take effect in the current and its sub-directories. In other words, they are inherited downward. In the example above, the single target will miss subdir-{as,cc}flags-y if they are defined in foo/Makefile. [2] could be built in a different directory As Documentation/kbuild/modules.rst section 4.3 says, Kbuild can handle files that are spread over several sub-directories. The build rule of foo/bar/baz.o may not necessarily be specified in foo/bar/Makefile. It might be specifies in foo/Makefile as follows: [foo/Makefile] obj-y := bar/baz.o This often happens when a module is so big that its source files are divided into sub-directories. In this case, there is no Makefile in the foo/bar/ directory, yet the single target descends into foo/bar/, then fails due to the missing Makefile. You can still do 'make foo/bar/' for partial building, but cannot do 'make foo/bar/baz.s'. I believe the single target '%.s' is a useful feature for inspecting the compiler output. Some modules work around this issue by putting an empty Makefile in every sub-directory. This commit fixes those problems by making the single target build descend in the same way as the normal build does. Another change is the single target build will observe the CONFIG options. Previously, it allowed users to build the foo.o even when the corresponding CONFIG_FOO is disabled: obj-$(CONFIG_FOO) += foo.o In the new behavior, the single target build will just fail and show "No rule to make target ..." (or "Nothing to be done for ..." if the stale object already exists, but cannot be updated). The disadvantage of this commit is the build speed. Now that the single target build visits every directory and parses lots of Makefiles, it is slower than before. (But, I hope it will not be too slow.) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14 15:19:18 +00:00
ifeq ($(need-modorder),)
ifneq ($(obj-m),)
$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
endif
endif
# ===========================================================================
# subdir-builtin and subdir-modorder may contain duplications. Use $(sort ...)
subdir-builtin := $(sort $(filter %/built-in.a, $(real-obj-y)))
subdir-modorder := $(sort $(filter %/modules.order, $(obj-m)))
targets-for-builtin := $(extra-y)
ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
targets-for-builtin += $(obj)/lib.a
endif
ifdef need-builtin
targets-for-builtin += $(obj)/built-in.a
endif
kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses the directory tree to determine which EXPORT_SYMBOL to trim. If an EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the second traverse, where some source files are recompiled with their EXPORT_SYMBOL() tuned into a no-op. Linus stated negative opinions about this slowness in commits: - 5cf0fd591f2e ("Kbuild: disable TRIM_UNUSED_KSYMS option") - a555bdd0c58c ("Kbuild: enable TRIM_UNUSED_KSYMS again, with some guarding") We can do this better now. The final data structures of EXPORT_SYMBOL are generated by the modpost stage, so modpost can selectively emit KSYMTAB entries that are really used by modules. Commit f73edc8951b2 ("kbuild: unify two modpost invocations") is another ground-work to do this in a one-pass algorithm. With the list of modules, modpost sets sym->used if it is used by a module. modpost emits KSYMTAB only for symbols with sym->used==true. BTW, Nicolas explained why the trimming was implemented with recursion: https://lore.kernel.org/all/2o2rpn97-79nq-p7s2-nq5-8p83391473r@syhkavp.arg/ Actually, we never achieved that level of optimization where the chain reaction of trimming comes into play because: - CONFIG_LTO_CLANG cannot remove any unused symbols - CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is enabled only for vmlinux, but not modules If deeper trimming is required, we need to revisit this, but I guess that is unlikely to happen. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-11 15:50:57 +00:00
targets-for-modules := $(foreach x, o mod, \
$(patsubst %.o, %.$x, $(filter %.o, $(obj-m))))
ifdef need-modorder
targets-for-modules += $(obj)/modules.order
endif
targets += $(targets-for-builtin) $(targets-for-modules)
# Linus' kernel sanity checking tool
ifeq ($(KBUILD_CHECKSRC),1)
quiet_cmd_checksrc = CHECK $<
cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
else ifeq ($(KBUILD_CHECKSRC),2)
quiet_cmd_force_checksrc = CHECK $<
cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $<
endif
ifneq ($(KBUILD_EXTRA_WARN),)
cmd_checkdoc = $(srctree)/scripts/kernel-doc -none $(KDOCFLAGS) \
$(if $(findstring 2, $(KBUILD_EXTRA_WARN)), -Wall) \
$<
endif
# Compile C sources (.c)
# ---------------------------------------------------------------------------
quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
kbuild: add support for Clang LTO This change adds build system support for Clang's Link Time Optimization (LTO). With -flto, instead of ELF object files, Clang produces LLVM bitcode, which is compiled into native code at link time, allowing the final binary to be optimized globally. For more details, see: https://llvm.org/docs/LinkTimeOptimization.html The Kconfig option CONFIG_LTO_CLANG is implemented as a choice, which defaults to LTO being disabled. To use LTO, the architecture must select ARCH_SUPPORTS_LTO_CLANG and support: - compiling with Clang, - compiling all assembly code with Clang's integrated assembler, - and linking with LLD. While using CONFIG_LTO_CLANG_FULL results in the best runtime performance, the compilation is not scalable in time or memory. CONFIG_LTO_CLANG_THIN enables ThinLTO, which allows parallel optimization and faster incremental builds. ThinLTO is used by default if the architecture also selects ARCH_SUPPORTS_LTO_CLANG_THIN: https://clang.llvm.org/docs/ThinLTO.html To enable LTO, LLVM tools must be used to handle bitcode files, by passing LLVM=1 and LLVM_IAS=1 options to make: $ make LLVM=1 LLVM_IAS=1 defconfig $ scripts/config -e LTO_CLANG_THIN $ make LLVM=1 LLVM_IAS=1 To prepare for LTO support with other compilers, common parts are gated behind the CONFIG_LTO option, and LTO can be disabled for specific files by filtering out CC_FLAGS_LTO. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20201211184633.3213045-3-samitolvanen@google.com
2020-12-11 18:46:19 +00:00
cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
$(obj)/%.s: $(src)/%.c FORCE
$(call if_changed_dep,cc_s_c)
quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
cmd_cpp_i_c = $(CPP) $(c_flags) -o $@ $<
$(obj)/%.i: $(src)/%.c FORCE
$(call if_changed_dep,cpp_i_c)
genksyms = scripts/genksyms/genksyms \
$(if $(1), -T $(2)) \
$(if $(KBUILD_PRESERVE), -p) \
-r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
# These mirror gensymtypes_S and co below, keep them in synch.
cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
kbuild: support for %.symtypes files Here is a patch that adds a new -T option to genksyms for generating dumps of the type definition that makes up the symbol version hashes. This allows to trace modversion changes back to what caused them. The dump format is the name of the type defined, followed by its definition (which is almost C): s#list_head struct list_head { s#list_head * next , * prev ; } The s#, u#, e#, and t# prefixes stand for struct, union, enum, and typedef. The exported symbols do not define types, and thus do not have an x# prefix: nfs4_acl_get_whotype int nfs4_acl_get_whotype ( char * , t#u32 ) The symbol type defintion of a single file can be generated with: make fs/jbd/journal.symtypes If KBUILD_SYMTYPES is defined, all the *.symtypes of all object files that export symbols are generated. The single *.symtypes files can be combined into a single file after a kernel build with a script like the following: for f in $(find -name '*.symtypes' | sort); do f=${f#./} echo "/* ${f%.symtypes}.o */" cat $f echo done \ | sed -e '\:UNKNOWN:d' \ -e 's:[,;] }:}:g' \ -e 's:\([[({]\) :\1:g' \ -e 's: \([])},;]\):\1:g' \ -e 's: $::' \ $f \ | awk ' /^.#/ { if (defined[$1] == $0) { print $1 next } defined[$1] = $0 } { print } ' When the kernel ABI changes, diffing individual *.symtype files, or the combined files, against each other will show which symbol changes caused the ABI changes. This can save a tremendous amount of time. Dump the types that make up modversions Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
2006-05-09 18:37:30 +00:00
quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
kbuild: support for %.symtypes files Here is a patch that adds a new -T option to genksyms for generating dumps of the type definition that makes up the symbol version hashes. This allows to trace modversion changes back to what caused them. The dump format is the name of the type defined, followed by its definition (which is almost C): s#list_head struct list_head { s#list_head * next , * prev ; } The s#, u#, e#, and t# prefixes stand for struct, union, enum, and typedef. The exported symbols do not define types, and thus do not have an x# prefix: nfs4_acl_get_whotype int nfs4_acl_get_whotype ( char * , t#u32 ) The symbol type defintion of a single file can be generated with: make fs/jbd/journal.symtypes If KBUILD_SYMTYPES is defined, all the *.symtypes of all object files that export symbols are generated. The single *.symtypes files can be combined into a single file after a kernel build with a script like the following: for f in $(find -name '*.symtypes' | sort); do f=${f#./} echo "/* ${f%.symtypes}.o */" cat $f echo done \ | sed -e '\:UNKNOWN:d' \ -e 's:[,;] }:}:g' \ -e 's:\([[({]\) :\1:g' \ -e 's: \([])},;]\):\1:g' \ -e 's: $::' \ $f \ | awk ' /^.#/ { if (defined[$1] == $0) { print $1 next } defined[$1] = $0 } { print } ' When the kernel ABI changes, diffing individual *.symtype files, or the combined files, against each other will show which symbol changes caused the ABI changes. This can save a tremendous amount of time. Dump the types that make up modversions Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
2006-05-09 18:37:30 +00:00
$(obj)/%.symtypes : $(src)/%.c FORCE
$(call cmd,cc_symtypes_c)
kbuild: support for %.symtypes files Here is a patch that adds a new -T option to genksyms for generating dumps of the type definition that makes up the symbol version hashes. This allows to trace modversion changes back to what caused them. The dump format is the name of the type defined, followed by its definition (which is almost C): s#list_head struct list_head { s#list_head * next , * prev ; } The s#, u#, e#, and t# prefixes stand for struct, union, enum, and typedef. The exported symbols do not define types, and thus do not have an x# prefix: nfs4_acl_get_whotype int nfs4_acl_get_whotype ( char * , t#u32 ) The symbol type defintion of a single file can be generated with: make fs/jbd/journal.symtypes If KBUILD_SYMTYPES is defined, all the *.symtypes of all object files that export symbols are generated. The single *.symtypes files can be combined into a single file after a kernel build with a script like the following: for f in $(find -name '*.symtypes' | sort); do f=${f#./} echo "/* ${f%.symtypes}.o */" cat $f echo done \ | sed -e '\:UNKNOWN:d' \ -e 's:[,;] }:}:g' \ -e 's:\([[({]\) :\1:g' \ -e 's: \([])},;]\):\1:g' \ -e 's: $::' \ $f \ | awk ' /^.#/ { if (defined[$1] == $0) { print $1 next } defined[$1] = $0 } { print } ' When the kernel ABI changes, diffing individual *.symtype files, or the combined files, against each other will show which symbol changes caused the ABI changes. This can save a tremendous amount of time. Dump the types that make up modversions Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
2006-05-09 18:37:30 +00:00
# LLVM assembly
# Generate .ll files from .c
quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@
cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -fno-discard-value-names -o $@ $<
$(obj)/%.ll: $(src)/%.c FORCE
$(call if_changed_dep,cc_ll_c)
# C (.c) files
# The C file is compiled and updated dependency information is generated.
# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
kbuild: do not create *.prelink.o for Clang LTO or IBT When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created for each module. Also, objtool is postponed until LLVM IR is converted to ELF. CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until objects are merged together. This commit stops generating *.prelink.o, so the build flow will look similar with/without LTO. The following figures show how the LTO build currently works, and how this commit is changing it. Current build flow ================== [1] single-object module $(LD) $(CC) +objtool $(LD) foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko (LLVM IR) (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module $(LD) $(CC) $(AR) +objtool $(LD) foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko | (archive) (ELF) | (ELF) foo2.c -----> foo2.o --/ | (LLVM IR) foo.mod.o --/ (LLVM IR) One confusion is that foo.o in multi-object module is an archive despite of its suffix. New build flow ============== [1] single-object module Since there is only one object, there is no need to keep the LLVM IR. Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO is disabled, $(LD) is unneeded because $(CC) produces an ELF object. $(CC)+$(LD)+objtool $(LD) foo.c ----------------------------> foo.o ---------> foo.ko (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module Previously, $(AR) was used to combine LLVM IR files into an archive, but there was no technical reason to do so. Use $(LD) to merge them into a single ELF object. $(LD) $(CC) +objtool $(LD) foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko | (ELF) | (ELF) foo2.c ---------> foo2.o ----/ | (LLVM IR) foo.mod.o --/ (LLVM IR) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64) Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
2022-05-27 10:01:49 +00:00
is-single-obj-m = $(and $(part-of-module),$(filter $@, $(obj-m)),y)
# When a module consists of a single object, there is no reason to keep LLVM IR.
# Make $(LD) covert LLVM IR to ELF here.
ifdef CONFIG_LTO_CLANG
cmd_ld_single_m = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@)
endif
quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
kbuild: do not create *.prelink.o for Clang LTO or IBT When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created for each module. Also, objtool is postponed until LLVM IR is converted to ELF. CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until objects are merged together. This commit stops generating *.prelink.o, so the build flow will look similar with/without LTO. The following figures show how the LTO build currently works, and how this commit is changing it. Current build flow ================== [1] single-object module $(LD) $(CC) +objtool $(LD) foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko (LLVM IR) (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module $(LD) $(CC) $(AR) +objtool $(LD) foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko | (archive) (ELF) | (ELF) foo2.c -----> foo2.o --/ | (LLVM IR) foo.mod.o --/ (LLVM IR) One confusion is that foo.o in multi-object module is an archive despite of its suffix. New build flow ============== [1] single-object module Since there is only one object, there is no need to keep the LLVM IR. Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO is disabled, $(LD) is unneeded because $(CC) produces an ELF object. $(CC)+$(LD)+objtool $(LD) foo.c ----------------------------> foo.o ---------> foo.ko (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module Previously, $(AR) was used to combine LLVM IR files into an archive, but there was no technical reason to do so. Use $(LD) to merge them into a single ELF object. $(LD) $(CC) +objtool $(LD) foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko | (ELF) | (ELF) foo2.c ---------> foo2.o ----/ | (LLVM IR) foo.mod.o --/ (LLVM IR) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64) Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
2022-05-27 10:01:49 +00:00
cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \
$(cmd_ld_single_m) \
$(cmd_objtool)
ifdef CONFIG_MODVERSIONS
# When module versioning is enabled the following steps are executed:
# o compile a <file>.o from <file>.c
kbuild: generate KSYMTAB entries by modpost Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way whether the EXPORT_SYMBOL() is placed in *.c or *.S. For further cleanups, this commit applies a similar approach to the entire data structure of EXPORT_SYMBOL(). The EXPORT_SYMBOL() compilation is split into two stages. When a source file is compiled, EXPORT_SYMBOL() will be converted into a dummy symbol in the .export_symbol section. For example, EXPORT_SYMBOL(foo); EXPORT_SYMBOL_NS_GPL(bar, BAR_NAMESPACE); will be encoded into the following assembly code: .section ".export_symbol","a" __export_symbol_foo: .asciz "" /* license */ .asciz "" /* name space */ .balign 8 .quad foo /* symbol reference */ .previous .section ".export_symbol","a" __export_symbol_bar: .asciz "GPL" /* license */ .asciz "BAR_NAMESPACE" /* name space */ .balign 8 .quad bar /* symbol reference */ .previous They are mere markers to tell modpost the name, license, and namespace of the symbols. They will be dropped from the final vmlinux and modules because the *(.export_symbol) will go into /DISCARD/ in the linker script. Then, modpost extracts all the information about EXPORT_SYMBOL() from the .export_symbol section, and generates the final C code: KSYMTAB_FUNC(foo, "", ""); KSYMTAB_FUNC(bar, "_gpl", "BAR_NAMESPACE"); KSYMTAB_FUNC() (or KSYMTAB_DATA() if it is data) is expanded to struct kernel_symbol that will be linked to the vmlinux or a module. With this change, EXPORT_SYMBOL() works in the same way for *.c and *.S files, providing the following benefits. [1] Deprecate EXPORT_DATA_SYMBOL() In the old days, EXPORT_SYMBOL() was only available in C files. To export a symbol in *.S, EXPORT_SYMBOL() was placed in a separate *.c file. arch/arm/kernel/armksyms.c is one example written in the classic manner. Commit 22823ab419d8 ("EXPORT_SYMBOL() for asm") removed this limitation. Since then, EXPORT_SYMBOL() can be placed close to the symbol definition in *.S files. It was a nice improvement. However, as that commit mentioned, you need to use EXPORT_DATA_SYMBOL() for data objects on some architectures. In the new approach, modpost checks symbol's type (STT_FUNC or not), and outputs KSYMTAB_FUNC() or KSYMTAB_DATA() accordingly. There are only two users of EXPORT_DATA_SYMBOL: EXPORT_DATA_SYMBOL_GPL(empty_zero_page) (arch/ia64/kernel/head.S) EXPORT_DATA_SYMBOL(ia64_ivt) (arch/ia64/kernel/ivt.S) They are transformed as follows and output into .vmlinux.export.c KSYMTAB_DATA(empty_zero_page, "_gpl", ""); KSYMTAB_DATA(ia64_ivt, "", ""); The other EXPORT_SYMBOL users in ia64 assembly are output as KSYMTAB_FUNC(). EXPORT_DATA_SYMBOL() is now deprecated. [2] merge <linux/export.h> and <asm-generic/export.h> There are two similar header implementations: include/linux/export.h for .c files include/asm-generic/export.h for .S files Ideally, the functionality should be consistent between them, but they tend to diverge. Commit 8651ec01daed ("module: add support for symbol namespaces.") did not support the namespace for *.S files. This commit shifts the essential implementation part to C, which supports EXPORT_SYMBOL_NS() for *.S files. <asm/export.h> and <asm-generic/export.h> will remain as a wrapper of <linux/export.h> for a while. They will be removed after #include <asm/export.h> directives are all replaced with #include <linux/export.h>. [3] Implement CONFIG_TRIM_UNUSED_KSYMS in one-pass algorithm (by a later commit) When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses the directory tree to determine which EXPORT_SYMBOL to trim. If an EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the second traverse, where some source files are recompiled with their EXPORT_SYMBOL() tuned into a no-op. We can do this better now; modpost can selectively emit KSYMTAB entries that are really used by modules. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-11 15:50:52 +00:00
# o if <file>.o doesn't contain a __export_symbol_*, i.e. does
# not export symbols, it's done.
# o otherwise, we calculate symbol versions using the good old
2022-05-13 11:39:22 +00:00
# genksyms on the preprocessed source and dump them into the .cmd file.
# o modpost will extract versions from that file and create *.c files that will
# be compiled and linked to the kernel and/or modules.
gen_symversions = \
kbuild: generate KSYMTAB entries by modpost Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way whether the EXPORT_SYMBOL() is placed in *.c or *.S. For further cleanups, this commit applies a similar approach to the entire data structure of EXPORT_SYMBOL(). The EXPORT_SYMBOL() compilation is split into two stages. When a source file is compiled, EXPORT_SYMBOL() will be converted into a dummy symbol in the .export_symbol section. For example, EXPORT_SYMBOL(foo); EXPORT_SYMBOL_NS_GPL(bar, BAR_NAMESPACE); will be encoded into the following assembly code: .section ".export_symbol","a" __export_symbol_foo: .asciz "" /* license */ .asciz "" /* name space */ .balign 8 .quad foo /* symbol reference */ .previous .section ".export_symbol","a" __export_symbol_bar: .asciz "GPL" /* license */ .asciz "BAR_NAMESPACE" /* name space */ .balign 8 .quad bar /* symbol reference */ .previous They are mere markers to tell modpost the name, license, and namespace of the symbols. They will be dropped from the final vmlinux and modules because the *(.export_symbol) will go into /DISCARD/ in the linker script. Then, modpost extracts all the information about EXPORT_SYMBOL() from the .export_symbol section, and generates the final C code: KSYMTAB_FUNC(foo, "", ""); KSYMTAB_FUNC(bar, "_gpl", "BAR_NAMESPACE"); KSYMTAB_FUNC() (or KSYMTAB_DATA() if it is data) is expanded to struct kernel_symbol that will be linked to the vmlinux or a module. With this change, EXPORT_SYMBOL() works in the same way for *.c and *.S files, providing the following benefits. [1] Deprecate EXPORT_DATA_SYMBOL() In the old days, EXPORT_SYMBOL() was only available in C files. To export a symbol in *.S, EXPORT_SYMBOL() was placed in a separate *.c file. arch/arm/kernel/armksyms.c is one example written in the classic manner. Commit 22823ab419d8 ("EXPORT_SYMBOL() for asm") removed this limitation. Since then, EXPORT_SYMBOL() can be placed close to the symbol definition in *.S files. It was a nice improvement. However, as that commit mentioned, you need to use EXPORT_DATA_SYMBOL() for data objects on some architectures. In the new approach, modpost checks symbol's type (STT_FUNC or not), and outputs KSYMTAB_FUNC() or KSYMTAB_DATA() accordingly. There are only two users of EXPORT_DATA_SYMBOL: EXPORT_DATA_SYMBOL_GPL(empty_zero_page) (arch/ia64/kernel/head.S) EXPORT_DATA_SYMBOL(ia64_ivt) (arch/ia64/kernel/ivt.S) They are transformed as follows and output into .vmlinux.export.c KSYMTAB_DATA(empty_zero_page, "_gpl", ""); KSYMTAB_DATA(ia64_ivt, "", ""); The other EXPORT_SYMBOL users in ia64 assembly are output as KSYMTAB_FUNC(). EXPORT_DATA_SYMBOL() is now deprecated. [2] merge <linux/export.h> and <asm-generic/export.h> There are two similar header implementations: include/linux/export.h for .c files include/asm-generic/export.h for .S files Ideally, the functionality should be consistent between them, but they tend to diverge. Commit 8651ec01daed ("module: add support for symbol namespaces.") did not support the namespace for *.S files. This commit shifts the essential implementation part to C, which supports EXPORT_SYMBOL_NS() for *.S files. <asm/export.h> and <asm-generic/export.h> will remain as a wrapper of <linux/export.h> for a while. They will be removed after #include <asm/export.h> directives are all replaced with #include <linux/export.h>. [3] Implement CONFIG_TRIM_UNUSED_KSYMS in one-pass algorithm (by a later commit) When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses the directory tree to determine which EXPORT_SYMBOL to trim. If an EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the second traverse, where some source files are recompiled with their EXPORT_SYMBOL() tuned into a no-op. We can do this better now; modpost can selectively emit KSYMTAB entries that are really used by modules. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-11 15:50:52 +00:00
if $(NM) $@ 2>/dev/null | grep -q ' __export_symbol_'; then \
$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
>> $(dot-target).cmd; \
fi
cmd_gen_symversions_c = $(call gen_symversions,c)
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
ifdef BUILD_C_RECORDMCOUNT
ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
RECORDMCOUNT_FLAGS = -w
endif
# Due to recursion, we must skip empty.o.
# The empty.o file is created in the make process in order to determine
# the target endianness and word size. It is made before all other C
# files, including recordmcount.
sub_cmd_record_mcount = \
if [ $(@) != "scripts/mod/empty.o" ]; then \
$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
fi;
recordmcount_source := $(srctree)/scripts/recordmcount.c \
$(srctree)/scripts/recordmcount.h
else
sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
"$(if $(CONFIG_64BIT),64,32)" \
"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
"$(if $(part-of-module),1,0)" "$(@)";
recordmcount_source := $(srctree)/scripts/recordmcount.pl
endif # BUILD_C_RECORDMCOUNT
cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
$(sub_cmd_record_mcount))
endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
ftrace: create __mcount_loc section This patch creates a section in the kernel called "__mcount_loc". This will hold a list of pointers to the mcount relocation for each call site of mcount. For example: objdump -dr init/main.o [...] Disassembly of section .text: 0000000000000000 <do_one_initcall>: 0: 55 push %rbp [...] 000000000000017b <init_post>: 17b: 55 push %rbp 17c: 48 89 e5 mov %rsp,%rbp 17f: 53 push %rbx 180: 48 83 ec 08 sub $0x8,%rsp 184: e8 00 00 00 00 callq 189 <init_post+0xe> 185: R_X86_64_PC32 mcount+0xfffffffffffffffc [...] We will add a section to point to each function call. .section __mcount_loc,"a",@progbits [...] .quad .text + 0x185 [...] The offset to of the mcount call site in init_post is an offset from the start of the section, and not the start of the function init_post. The mcount relocation is at the call site 0x185 from the start of the .text section. .text + 0x185 == init_post + 0xa We need a way to add this __mcount_loc section in a way that we do not lose the relocations after final link. The .text section here will be attached to all other .text sections after final link and the offsets will be meaningless. We need to keep track of where these .text sections are. To do this, we use the start of the first function in the section. do_one_initcall. We can make a tmp.s file with this function as a reference to the start of the .text section. .section __mcount_loc,"a",@progbits [...] .quad do_one_initcall + 0x185 [...] Then we can compile the tmp.s into a tmp.o gcc -c tmp.s -o tmp.o And link it into back into main.o. ld -r main.o tmp.o -o tmp_main.o mv tmp_main.o main.o But we have a problem. What happens if the first function in a section is not exported, and is a static function. The linker will not let the tmp.o use it. This case exists in main.o as well. Disassembly of section .init.text: 0000000000000000 <set_reset_devices>: 0: 55 push %rbp 1: 48 89 e5 mov %rsp,%rbp 4: e8 00 00 00 00 callq 9 <set_reset_devices+0x9> 5: R_X86_64_PC32 mcount+0xfffffffffffffffc The first function in .init.text is a static function. 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 t set_reset_devices The lowercase 't' means that set_reset_devices is local and is not exported. If we simply try to link the tmp.o with the set_reset_devices we end up with two symbols: one local and one global. .section __mcount_loc,"a",@progbits .quad set_reset_devices + 0x10 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 t set_reset_devices U set_reset_devices We still have an undefined reference to set_reset_devices, and if we try to compile the kernel, we will end up with an undefined reference to set_reset_devices, or even worst, it could be exported someplace else, and then we will have a reference to the wrong location. To handle this case, we make an intermediate step using objcopy. We convert set_reset_devices into a global exported symbol before linking it with tmp.o and set it back afterwards. 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 T set_reset_devices 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 T set_reset_devices 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 t set_reset_devices Now we have a section in main.o called __mcount_loc that we can place somewhere in the kernel using vmlinux.ld.S and access it to convert all these locations that call mcount into nops before starting SMP and thus, eliminating the need to do this with kstop_machine. Note, A well documented perl script (scripts/recordmcount.pl) is used to do all this in one location. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-14 19:45:07 +00:00
# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
kbuild: do not create *.prelink.o for Clang LTO or IBT When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created for each module. Also, objtool is postponed until LLVM IR is converted to ELF. CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until objects are merged together. This commit stops generating *.prelink.o, so the build flow will look similar with/without LTO. The following figures show how the LTO build currently works, and how this commit is changing it. Current build flow ================== [1] single-object module $(LD) $(CC) +objtool $(LD) foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko (LLVM IR) (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module $(LD) $(CC) $(AR) +objtool $(LD) foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko | (archive) (ELF) | (ELF) foo2.c -----> foo2.o --/ | (LLVM IR) foo.mod.o --/ (LLVM IR) One confusion is that foo.o in multi-object module is an archive despite of its suffix. New build flow ============== [1] single-object module Since there is only one object, there is no need to keep the LLVM IR. Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO is disabled, $(LD) is unneeded because $(CC) produces an ELF object. $(CC)+$(LD)+objtool $(LD) foo.c ----------------------------> foo.o ---------> foo.ko (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module Previously, $(AR) was used to combine LLVM IR files into an archive, but there was no technical reason to do so. Use $(LD) to merge them into a single ELF object. $(LD) $(CC) +objtool $(LD) foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko | (ELF) | (ELF) foo2.c ---------> foo2.o ----/ | (LLVM IR) foo.mod.o --/ (LLVM IR) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64) Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
2022-05-27 10:01:49 +00:00
is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
kbuild: do not create *.prelink.o for Clang LTO or IBT When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created for each module. Also, objtool is postponed until LLVM IR is converted to ELF. CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until objects are merged together. This commit stops generating *.prelink.o, so the build flow will look similar with/without LTO. The following figures show how the LTO build currently works, and how this commit is changing it. Current build flow ================== [1] single-object module $(LD) $(CC) +objtool $(LD) foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko (LLVM IR) (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module $(LD) $(CC) $(AR) +objtool $(LD) foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko | (archive) (ELF) | (ELF) foo2.c -----> foo2.o --/ | (LLVM IR) foo.mod.o --/ (LLVM IR) One confusion is that foo.o in multi-object module is an archive despite of its suffix. New build flow ============== [1] single-object module Since there is only one object, there is no need to keep the LLVM IR. Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO is disabled, $(LD) is unneeded because $(CC) produces an ELF object. $(CC)+$(LD)+objtool $(LD) foo.c ----------------------------> foo.o ---------> foo.ko (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module Previously, $(AR) was used to combine LLVM IR files into an archive, but there was no technical reason to do so. Use $(LD) to merge them into a single ELF object. $(LD) $(CC) +objtool $(LD) foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko | (ELF) | (ELF) foo2.c ---------> foo2.o ----/ | (LLVM IR) foo.mod.o --/ (LLVM IR) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64) Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
2022-05-27 10:01:49 +00:00
$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
kbuild: warn objects shared among multiple modules If an object is shared among multiple modules, and some of them are configured as 'm', but the others as 'y', the shared object is built as modular, then linked to the modules and vmlinux. This is a potential issue because the expected CFLAGS are different between modules and builtins. Commit 637a642f5ca5 ("zstd: Fixing mixed module-builtin objects") reported that this could be even more fatal in some cases such as Clang LTO. That commit fixed lib/zlib/zstd_{compress,decompress}, but there are still more instances of breakage. This commit adds a W=1 warning for shared objects, so that the kbuild test robot, which provides build tests with W=1, will avoid a new breakage slipping in. Quick compile tests on v6.1-rc4 detected the following: scripts/Makefile.build:252: ./drivers/block/rnbd/Makefile: rnbd-common.o is added to multiple modules: rnbd-client rnbd-server scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: cn10k_cpt.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: otx2_cptlf.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: otx2_cpt_mbox_common.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/edac/Makefile: skx_common.o is added to multiple modules: i10nm_edac skx_edac scripts/Makefile.build:252: ./drivers/gpu/drm/bridge/imx/Makefile: imx-ldb-helper.o is added to multiple modules: imx8qm-ldb imx8qxp-ldb scripts/Makefile.build:252: ./drivers/mfd/Makefile: rsmu_core.o is added to multiple modules: rsmu-i2c rsmu-spi scripts/Makefile.build:252: ./drivers/mtd/tests/Makefile: mtd_test.o is added to multiple modules: mtd_nandbiterrs mtd_oobtest mtd_pagetest mtd_readtest mtd_speedtest mtd_stresstest mtd_subpagetest mtd_torturetest scripts/Makefile.build:252: ./drivers/net/dsa/ocelot/Makefile: felix.o is added to multiple modules: mscc_felix mscc_seville scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn23xx_pf_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn23xx_vf_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn66xx_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn68xx_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: lio_core.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: lio_ethtool.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_droq.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_mailbox.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_mem_ops.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_nic.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: request_manager.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: response_manager.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefile: dpaa2-mac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefile: dpmac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc_cbdr.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc_ethtool.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_cmd.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_rss.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_tqp_stats.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/Makefile: otx2_dcbnl.o is added to multiple modules: rvu_nicpf rvu_nicvf scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/Makefile: otx2_devlink.o is added to multiple modules: rvu_nicpf rvu_nicvf scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_ale.o is added to multiple modules: keystone_netcp keystone_netcp_ethss ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_ethtool.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_priv.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_sl.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: davinci_cpdma.o is added to multiple modules: ti_cpsw ti_cpsw_new ti_davinci_emac scripts/Makefile.build:252: ./drivers/platform/x86/intel/int3472/Makefile: common.o is added to multiple modules: intel_skl_int3472_discrete intel_skl_int3472_tps68470 scripts/Makefile.build:252: ./sound/soc/codecs/Makefile: wcd-clsh-v2.o is added to multiple modules: snd-soc-wcd9335 snd-soc-wcd934x snd-soc-wcd938x Once all the warnings are fixed, it can become an error without the W= option. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Tested-by: Alexander Lobakin <alobakin@pm.me> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2022-11-18 19:15:51 +00:00
ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
endif
define rule_cc_o_c
kbuild: change if_changed_rule for multi-line recipe The 'define' ... 'endef' directive is useful to confine a series of shell commands into a single macro: define foo [action1] [action2] [action3] endif Each action is executed in a separate subshell. However, rule_cc_o_c and rule_as_o_S in scripts/Makefile.build are written as follows (with a trailing semicolon in each cmd_*): define rule_cc_o_c [action1] ; \ [action2] ; \ [action3] ; endef All shell commands are concatenated with '; \' so that it looks like a single command from the Makefile point of view. This does not exploit the benefits of 'define' ... 'endef' form because a single shell command can be more simply written, like this: rule_cc_o_c = \ [action1] ; \ [action2] ; \ [action3] ; I guess the intention for the command concatenation was to let the '@set -e' in if_changed_rule cover all the commands. We can improve the readability by moving '@set -e' to the 'cmd' macro. The combo of $(call echo-cmd,*) $(cmd_*) in rule_cc_o_c and rule_as_o_S have been replaced with $(call cmd,*). The trailing back-slashes have been removed. Here is a note about the performance: the commands in rule_cc_o_c and rule_as_o_S were previously executed all together in a single subshell, but now each line in a separate subshell. This means Make will spawn extra subshells [1]. I measured the build performance for x86_64_defconfig + CONFIG_MODVERSIONS + CONFIG_TRIM_UNUSED_KSYMS and I saw slight performance regression, but I believe code readability and maintainability wins. [1] Precisely, GNU Make may optimize this by executing the command directly instead of forking a subshell, if no shell special characters are found in the command line and omitting the subshell will not change the behavior. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-11-30 01:05:27 +00:00
$(call cmd_and_fixdep,cc_o_c)
$(call cmd,checksrc)
kbuild: change if_changed_rule for multi-line recipe The 'define' ... 'endef' directive is useful to confine a series of shell commands into a single macro: define foo [action1] [action2] [action3] endif Each action is executed in a separate subshell. However, rule_cc_o_c and rule_as_o_S in scripts/Makefile.build are written as follows (with a trailing semicolon in each cmd_*): define rule_cc_o_c [action1] ; \ [action2] ; \ [action3] ; endef All shell commands are concatenated with '; \' so that it looks like a single command from the Makefile point of view. This does not exploit the benefits of 'define' ... 'endef' form because a single shell command can be more simply written, like this: rule_cc_o_c = \ [action1] ; \ [action2] ; \ [action3] ; I guess the intention for the command concatenation was to let the '@set -e' in if_changed_rule cover all the commands. We can improve the readability by moving '@set -e' to the 'cmd' macro. The combo of $(call echo-cmd,*) $(cmd_*) in rule_cc_o_c and rule_as_o_S have been replaced with $(call cmd,*). The trailing back-slashes have been removed. Here is a note about the performance: the commands in rule_cc_o_c and rule_as_o_S were previously executed all together in a single subshell, but now each line in a separate subshell. This means Make will spawn extra subshells [1]. I measured the build performance for x86_64_defconfig + CONFIG_MODVERSIONS + CONFIG_TRIM_UNUSED_KSYMS and I saw slight performance regression, but I believe code readability and maintainability wins. [1] Precisely, GNU Make may optimize this by executing the command directly instead of forking a subshell, if no shell special characters are found in the command line and omitting the subshell will not change the behavior. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-11-30 01:05:27 +00:00
$(call cmd,checkdoc)
$(call cmd,gen_objtooldep)
$(call cmd,gen_symversions_c)
kbuild: change if_changed_rule for multi-line recipe The 'define' ... 'endef' directive is useful to confine a series of shell commands into a single macro: define foo [action1] [action2] [action3] endif Each action is executed in a separate subshell. However, rule_cc_o_c and rule_as_o_S in scripts/Makefile.build are written as follows (with a trailing semicolon in each cmd_*): define rule_cc_o_c [action1] ; \ [action2] ; \ [action3] ; endef All shell commands are concatenated with '; \' so that it looks like a single command from the Makefile point of view. This does not exploit the benefits of 'define' ... 'endef' form because a single shell command can be more simply written, like this: rule_cc_o_c = \ [action1] ; \ [action2] ; \ [action3] ; I guess the intention for the command concatenation was to let the '@set -e' in if_changed_rule cover all the commands. We can improve the readability by moving '@set -e' to the 'cmd' macro. The combo of $(call echo-cmd,*) $(cmd_*) in rule_cc_o_c and rule_as_o_S have been replaced with $(call cmd,*). The trailing back-slashes have been removed. Here is a note about the performance: the commands in rule_cc_o_c and rule_as_o_S were previously executed all together in a single subshell, but now each line in a separate subshell. This means Make will spawn extra subshells [1]. I measured the build performance for x86_64_defconfig + CONFIG_MODVERSIONS + CONFIG_TRIM_UNUSED_KSYMS and I saw slight performance regression, but I believe code readability and maintainability wins. [1] Precisely, GNU Make may optimize this by executing the command directly instead of forking a subshell, if no shell special characters are found in the command line and omitting the subshell will not change the behavior. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-11-30 01:05:27 +00:00
$(call cmd,record_mcount)
kbuild: warn objects shared among multiple modules If an object is shared among multiple modules, and some of them are configured as 'm', but the others as 'y', the shared object is built as modular, then linked to the modules and vmlinux. This is a potential issue because the expected CFLAGS are different between modules and builtins. Commit 637a642f5ca5 ("zstd: Fixing mixed module-builtin objects") reported that this could be even more fatal in some cases such as Clang LTO. That commit fixed lib/zlib/zstd_{compress,decompress}, but there are still more instances of breakage. This commit adds a W=1 warning for shared objects, so that the kbuild test robot, which provides build tests with W=1, will avoid a new breakage slipping in. Quick compile tests on v6.1-rc4 detected the following: scripts/Makefile.build:252: ./drivers/block/rnbd/Makefile: rnbd-common.o is added to multiple modules: rnbd-client rnbd-server scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: cn10k_cpt.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: otx2_cptlf.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: otx2_cpt_mbox_common.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/edac/Makefile: skx_common.o is added to multiple modules: i10nm_edac skx_edac scripts/Makefile.build:252: ./drivers/gpu/drm/bridge/imx/Makefile: imx-ldb-helper.o is added to multiple modules: imx8qm-ldb imx8qxp-ldb scripts/Makefile.build:252: ./drivers/mfd/Makefile: rsmu_core.o is added to multiple modules: rsmu-i2c rsmu-spi scripts/Makefile.build:252: ./drivers/mtd/tests/Makefile: mtd_test.o is added to multiple modules: mtd_nandbiterrs mtd_oobtest mtd_pagetest mtd_readtest mtd_speedtest mtd_stresstest mtd_subpagetest mtd_torturetest scripts/Makefile.build:252: ./drivers/net/dsa/ocelot/Makefile: felix.o is added to multiple modules: mscc_felix mscc_seville scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn23xx_pf_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn23xx_vf_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn66xx_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn68xx_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: lio_core.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: lio_ethtool.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_droq.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_mailbox.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_mem_ops.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_nic.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: request_manager.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: response_manager.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefile: dpaa2-mac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefile: dpmac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc_cbdr.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc_ethtool.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_cmd.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_rss.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_tqp_stats.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/Makefile: otx2_dcbnl.o is added to multiple modules: rvu_nicpf rvu_nicvf scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/Makefile: otx2_devlink.o is added to multiple modules: rvu_nicpf rvu_nicvf scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_ale.o is added to multiple modules: keystone_netcp keystone_netcp_ethss ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_ethtool.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_priv.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_sl.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: davinci_cpdma.o is added to multiple modules: ti_cpsw ti_cpsw_new ti_davinci_emac scripts/Makefile.build:252: ./drivers/platform/x86/intel/int3472/Makefile: common.o is added to multiple modules: intel_skl_int3472_discrete intel_skl_int3472_tps68470 scripts/Makefile.build:252: ./sound/soc/codecs/Makefile: wcd-clsh-v2.o is added to multiple modules: snd-soc-wcd9335 snd-soc-wcd934x snd-soc-wcd938x Once all the warnings are fixed, it can become an error without the W= option. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Tested-by: Alexander Lobakin <alobakin@pm.me> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2022-11-18 19:15:51 +00:00
$(call cmd,warn_shared_object)
endef
define rule_as_o_S
kbuild: change if_changed_rule for multi-line recipe The 'define' ... 'endef' directive is useful to confine a series of shell commands into a single macro: define foo [action1] [action2] [action3] endif Each action is executed in a separate subshell. However, rule_cc_o_c and rule_as_o_S in scripts/Makefile.build are written as follows (with a trailing semicolon in each cmd_*): define rule_cc_o_c [action1] ; \ [action2] ; \ [action3] ; endef All shell commands are concatenated with '; \' so that it looks like a single command from the Makefile point of view. This does not exploit the benefits of 'define' ... 'endef' form because a single shell command can be more simply written, like this: rule_cc_o_c = \ [action1] ; \ [action2] ; \ [action3] ; I guess the intention for the command concatenation was to let the '@set -e' in if_changed_rule cover all the commands. We can improve the readability by moving '@set -e' to the 'cmd' macro. The combo of $(call echo-cmd,*) $(cmd_*) in rule_cc_o_c and rule_as_o_S have been replaced with $(call cmd,*). The trailing back-slashes have been removed. Here is a note about the performance: the commands in rule_cc_o_c and rule_as_o_S were previously executed all together in a single subshell, but now each line in a separate subshell. This means Make will spawn extra subshells [1]. I measured the build performance for x86_64_defconfig + CONFIG_MODVERSIONS + CONFIG_TRIM_UNUSED_KSYMS and I saw slight performance regression, but I believe code readability and maintainability wins. [1] Precisely, GNU Make may optimize this by executing the command directly instead of forking a subshell, if no shell special characters are found in the command line and omitting the subshell will not change the behavior. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-11-30 01:05:27 +00:00
$(call cmd_and_fixdep,as_o_S)
$(call cmd,gen_objtooldep)
$(call cmd,gen_symversions_S)
kbuild: warn objects shared among multiple modules If an object is shared among multiple modules, and some of them are configured as 'm', but the others as 'y', the shared object is built as modular, then linked to the modules and vmlinux. This is a potential issue because the expected CFLAGS are different between modules and builtins. Commit 637a642f5ca5 ("zstd: Fixing mixed module-builtin objects") reported that this could be even more fatal in some cases such as Clang LTO. That commit fixed lib/zlib/zstd_{compress,decompress}, but there are still more instances of breakage. This commit adds a W=1 warning for shared objects, so that the kbuild test robot, which provides build tests with W=1, will avoid a new breakage slipping in. Quick compile tests on v6.1-rc4 detected the following: scripts/Makefile.build:252: ./drivers/block/rnbd/Makefile: rnbd-common.o is added to multiple modules: rnbd-client rnbd-server scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: cn10k_cpt.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: otx2_cptlf.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: otx2_cpt_mbox_common.o is added to multiple modules: rvu_cptpf rvu_cptvf scripts/Makefile.build:252: ./drivers/edac/Makefile: skx_common.o is added to multiple modules: i10nm_edac skx_edac scripts/Makefile.build:252: ./drivers/gpu/drm/bridge/imx/Makefile: imx-ldb-helper.o is added to multiple modules: imx8qm-ldb imx8qxp-ldb scripts/Makefile.build:252: ./drivers/mfd/Makefile: rsmu_core.o is added to multiple modules: rsmu-i2c rsmu-spi scripts/Makefile.build:252: ./drivers/mtd/tests/Makefile: mtd_test.o is added to multiple modules: mtd_nandbiterrs mtd_oobtest mtd_pagetest mtd_readtest mtd_speedtest mtd_stresstest mtd_subpagetest mtd_torturetest scripts/Makefile.build:252: ./drivers/net/dsa/ocelot/Makefile: felix.o is added to multiple modules: mscc_felix mscc_seville scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn23xx_pf_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn23xx_vf_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn66xx_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: cn68xx_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: lio_core.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: lio_ethtool.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_device.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_droq.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_mailbox.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_mem_ops.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: octeon_nic.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: request_manager.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefile: response_manager.o is added to multiple modules: liquidio liquidio_vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefile: dpaa2-mac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefile: dpmac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc_cbdr.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc_ethtool.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefile: enetc.o is added to multiple modules: fsl-enetc fsl-enetc-vf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_cmd.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_rss.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefile: hns3_common/hclge_comm_tqp_stats.o is added to multiple modules: hclge hclgevf scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/Makefile: otx2_dcbnl.o is added to multiple modules: rvu_nicpf rvu_nicvf scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/Makefile: otx2_devlink.o is added to multiple modules: rvu_nicpf rvu_nicvf scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_ale.o is added to multiple modules: keystone_netcp keystone_netcp_ethss ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_ethtool.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_priv.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_sl.o is added to multiple modules: ti_cpsw ti_cpsw_new scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: davinci_cpdma.o is added to multiple modules: ti_cpsw ti_cpsw_new ti_davinci_emac scripts/Makefile.build:252: ./drivers/platform/x86/intel/int3472/Makefile: common.o is added to multiple modules: intel_skl_int3472_discrete intel_skl_int3472_tps68470 scripts/Makefile.build:252: ./sound/soc/codecs/Makefile: wcd-clsh-v2.o is added to multiple modules: snd-soc-wcd9335 snd-soc-wcd934x snd-soc-wcd938x Once all the warnings are fixed, it can become an error without the W= option. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Tested-by: Alexander Lobakin <alobakin@pm.me> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2022-11-18 19:15:51 +00:00
$(call cmd,warn_shared_object)
endef
# Built-in and composite module parts
$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
$(call if_changed_rule,cc_o_c)
$(call cmd,force_checksrc)
# To make this rule robust against "Argument list too long" error,
# ensure to add $(obj)/ prefix by a shell command.
kbuild: avoid regex RS for POSIX awk In 22f26f21774f8 awk was added to deduplicate *.mod files. The awk invocation passes -v RS='( |\n)' to match a space or newline character as the record separator. Unfortunately, POSIX states[1] > If RS contains more than one character, the results are unspecified. Some implementations (such as the One True Awk[2] used by the BSDs) do not treat RS as a regular expression. When awk does not support regex RS, build failures such as the following are produced (first error using allmodconfig): CC [M] arch/x86/events/intel/uncore.o CC [M] arch/x86/events/intel/uncore_nhmex.o CC [M] arch/x86/events/intel/uncore_snb.o CC [M] arch/x86/events/intel/uncore_snbep.o CC [M] arch/x86/events/intel/uncore_discovery.o LD [M] arch/x86/events/intel/intel-uncore.o ld: cannot find uncore_nhmex.o: No such file or directory ld: cannot find uncore_snb.o: No such file or directory ld: cannot find uncore_snbep.o: No such file or directory ld: cannot find uncore_discovery.o: No such file or directory make[3]: *** [scripts/Makefile.build:422: arch/x86/events/intel/intel-uncore.o] Error 1 make[2]: *** [scripts/Makefile.build:487: arch/x86/events/intel] Error 2 make[1]: *** [scripts/Makefile.build:487: arch/x86/events] Error 2 make: *** [Makefile:1839: arch/x86] Error 2 To avoid this, use printf(1) to produce a newline between each object path, instead of the space produced by echo(1), so that the default RS can be used by awk. [1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html [2]: https://github.com/onetrueawk/awk Fixes: 22f26f21774f ("kbuild: get rid of duplication in *.mod files") Signed-off-by: Kevin Locke <kevin@kevinlocke.name> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-06-07 02:42:54 +00:00
cmd_mod = printf '%s\n' $(call real-search, $*.o, .o, -objs -y -m) | \
$(AWK) '!x[$$0]++ { print("$(obj)/"$$0) }' > $@
$(obj)/%.mod: FORCE
$(call if_changed,mod)
quiet_cmd_cc_lst_c = MKLST $@
cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
$(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
System.map $(OBJDUMP) > $@
$(obj)/%.lst: $(src)/%.c FORCE
$(call if_changed_dep,cc_lst_c)
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
# Compile Rust sources (.rs)
# ---------------------------------------------------------------------------
rust: workqueue: add helper for defining work_struct fields The main challenge with defining `work_struct` fields is making sure that the function pointer stored in the `work_struct` is appropriate for the work item type it is embedded in. It needs to know the offset of the `work_struct` field being used (even if there are several!) so that it can do a `container_of`, and it needs to know the type of the work item so that it can call into the right user-provided code. All of this needs to happen in a way that provides a safe API to the user, so that users of the workqueue cannot mix up the function pointers. There are three important pieces that are relevant when doing this: * The pointer type. * The work item struct. This is what the pointer points at. * The `work_struct` field. This is a field of the work item struct. This patch introduces a separate trait for each piece. The pointer type is given a `WorkItemPointer` trait, which pointer types need to implement to be usable with the workqueue. This trait will be implemented for `Arc` and `Box` in a later patch in this patchset. Implementing this trait is unsafe because this is where the `container_of` operation happens, but user-code will not need to implement it themselves. The work item struct should then implement the `WorkItem` trait. This trait is where user-code specifies what they want to happen when a work item is executed. It also specifies what the correct pointer type is. Finally, to make the work item struct know the offset of its `work_struct` field, we use a trait called `HasWork<T, ID>`. If a type implements this trait, then the type declares that, at the given offset, there is a field of type `Work<T, ID>`. The trait is marked unsafe because the OFFSET constant must be correct, but we provide an `impl_has_work!` macro that can safely implement `HasWork<T>` on a type. The macro expands to something that only compiles if the specified field really has the type `Work<T>`. It is used like this: ``` struct MyWorkItem { work_field: Work<MyWorkItem, 1>, } impl_has_work! { impl HasWork<MyWorkItem, 1> for MyWorkItem { self.work_field } } ``` Note that since the `Work` type is annotated with an id, you can have several `work_struct` fields by using a different id for each one. Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2023-08-28 10:48:04 +00:00
rust_allowed_features := new_uninit,offset_of
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
# `--out-dir` is required to avoid temporaries being created by `rustc` in the
# current working directory, which may be not accessible in the out-of-tree
# modules case.
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
rust_common_cmd = \
RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \
-Zallow-features=$(rust_allowed_features) \
-Zcrate-attr=no_std \
-Zcrate-attr='feature($(rust_allowed_features))' \
--extern alloc --extern kernel \
kbuild: specify output names separately for each emission type from rustc In Kbuild, two different rules must not write to the same file, but it happens when compiling rust source files. For example, set CONFIG_SAMPLE_RUST_MINIMAL=m and run the following: $ make -j$(nproc) samples/rust/rust_minimal.o samples/rust/rust_minimal.rsi \ samples/rust/rust_minimal.s samples/rust/rust_minimal.ll [snip] RUSTC [M] samples/rust/rust_minimal.o RUSTC [M] samples/rust/rust_minimal.rsi RUSTC [M] samples/rust/rust_minimal.s RUSTC [M] samples/rust/rust_minimal.ll mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory make[3]: *** [scripts/Makefile.build:334: samples/rust/rust_minimal.ll] Error 1 make[3]: *** Waiting for unfinished jobs.... mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory make[3]: *** [scripts/Makefile.build:309: samples/rust/rust_minimal.o] Error 1 mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory make[3]: *** [scripts/Makefile.build:326: samples/rust/rust_minimal.s] Error 1 make[2]: *** [scripts/Makefile.build:504: samples/rust] Error 2 make[1]: *** [scripts/Makefile.build:504: samples] Error 2 make: *** [Makefile:2008: .] Error 2 The reason for the error is that 4 threads running in parallel renames the same file, samples/rust/rust_minimal.d. This does not happen when compiling C or assembly files because -Wp,-MMD,$(depfile) explicitly specifies the dependency filepath. $(depfile) is a unique path for each target. Currently, rustc is only given --out-dir and --emit=<list-of-types> So, all the rust build rules output the dep-info into the default <CRATE_NAME>.d, which causes the path conflict. Fortunately, the --emit option is able to specify the output path individually, with the form --emit=<type>=<path>. Add --emit=dep-info=$(depfile) to the common part. Also, remove the redundant --out-dir because the output path is specified for each type. The code gets much cleaner because we do not need to rename *.d files. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Tested-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
2023-01-07 09:18:15 +00:00
--crate-type rlib -L $(objtree)/rust/ \
--crate-name $(basename $(notdir $@)) \
--sysroot=/dev/null \
--out-dir $(dir $@) --emit=dep-info=$(depfile)
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
# `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
# will be used. We explicitly request `-Ccodegen-units=1` in any case, and
# the compiler shows a warning if it is not 1. However, if we ever stop
# requesting it explicitly and we start using some other `--emit` that does not
# imply it (and for which codegen is performed), then we would be out of sync,
# i.e. the outputs we would get for the different single targets (e.g. `.ll`)
# would not match each other.
quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
$(obj)/%.o: $(src)/%.rs FORCE
$(call if_changed_dep,rustc_o_rs)
quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
cmd_rustc_rsi_rs = \
kbuild: specify output names separately for each emission type from rustc In Kbuild, two different rules must not write to the same file, but it happens when compiling rust source files. For example, set CONFIG_SAMPLE_RUST_MINIMAL=m and run the following: $ make -j$(nproc) samples/rust/rust_minimal.o samples/rust/rust_minimal.rsi \ samples/rust/rust_minimal.s samples/rust/rust_minimal.ll [snip] RUSTC [M] samples/rust/rust_minimal.o RUSTC [M] samples/rust/rust_minimal.rsi RUSTC [M] samples/rust/rust_minimal.s RUSTC [M] samples/rust/rust_minimal.ll mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory make[3]: *** [scripts/Makefile.build:334: samples/rust/rust_minimal.ll] Error 1 make[3]: *** Waiting for unfinished jobs.... mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory make[3]: *** [scripts/Makefile.build:309: samples/rust/rust_minimal.o] Error 1 mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory make[3]: *** [scripts/Makefile.build:326: samples/rust/rust_minimal.s] Error 1 make[2]: *** [scripts/Makefile.build:504: samples/rust] Error 2 make[1]: *** [scripts/Makefile.build:504: samples] Error 2 make: *** [Makefile:2008: .] Error 2 The reason for the error is that 4 threads running in parallel renames the same file, samples/rust/rust_minimal.d. This does not happen when compiling C or assembly files because -Wp,-MMD,$(depfile) explicitly specifies the dependency filepath. $(depfile) is a unique path for each target. Currently, rustc is only given --out-dir and --emit=<list-of-types> So, all the rust build rules output the dep-info into the default <CRATE_NAME>.d, which causes the path conflict. Fortunately, the --emit option is able to specify the output path individually, with the form --emit=<type>=<path>. Add --emit=dep-info=$(depfile) to the common part. Also, remove the redundant --out-dir because the output path is specified for each type. The code gets much cleaner because we do not need to rename *.d files. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Tested-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
2023-01-07 09:18:15 +00:00
$(rust_common_cmd) -Zunpretty=expanded $< >$@; \
command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
$(obj)/%.rsi: $(src)/%.rs FORCE
$(call if_changed_dep,rustc_rsi_rs)
quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
$(obj)/%.s: $(src)/%.rs FORCE
$(call if_changed_dep,rustc_s_rs)
quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<
Kbuild: add Rust support Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com> Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com> Co-developed-by: Finn Behrens <me@kloenk.de> Signed-off-by: Finn Behrens <me@kloenk.de> Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com> Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com> Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com> Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com> Co-developed-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com> Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com> Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Co-developed-by: Boris-Chengbiao Zhou <bobo1239@web.de> Signed-off-by: Boris-Chengbiao Zhou <bobo1239@web.de> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Douglas Su <d0u9.su@outlook.com> Signed-off-by: Douglas Su <d0u9.su@outlook.com> Co-developed-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Signed-off-by: Dariusz Sosnowski <dsosnowski@dsosnowski.pl> Co-developed-by: Antonio Terceiro <antonio.terceiro@linaro.org> Signed-off-by: Antonio Terceiro <antonio.terceiro@linaro.org> Co-developed-by: Daniel Xu <dxu@dxuuu.xyz> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Co-developed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2021-07-03 14:42:57 +00:00
$(obj)/%.ll: $(src)/%.rs FORCE
$(call if_changed_dep,rustc_ll_rs)
# Compile assembler sources (.S)
# ---------------------------------------------------------------------------
# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
# or a file that it includes, in order to get versioned symbols. We build a
# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
#
# This is convoluted. The .S file must first be preprocessed to run guards and
# expand names, then the resulting exports must be constructed into plain
# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
# to make the genksyms input.
#
# These mirror gensymtypes_c and co above, keep them in synch.
cmd_gensymtypes_S = \
{ echo "\#include <linux/kernel.h>" ; \
echo "\#include <asm/asm-prototypes.h>" ; \
kbuild: generate KSYMTAB entries by modpost Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way whether the EXPORT_SYMBOL() is placed in *.c or *.S. For further cleanups, this commit applies a similar approach to the entire data structure of EXPORT_SYMBOL(). The EXPORT_SYMBOL() compilation is split into two stages. When a source file is compiled, EXPORT_SYMBOL() will be converted into a dummy symbol in the .export_symbol section. For example, EXPORT_SYMBOL(foo); EXPORT_SYMBOL_NS_GPL(bar, BAR_NAMESPACE); will be encoded into the following assembly code: .section ".export_symbol","a" __export_symbol_foo: .asciz "" /* license */ .asciz "" /* name space */ .balign 8 .quad foo /* symbol reference */ .previous .section ".export_symbol","a" __export_symbol_bar: .asciz "GPL" /* license */ .asciz "BAR_NAMESPACE" /* name space */ .balign 8 .quad bar /* symbol reference */ .previous They are mere markers to tell modpost the name, license, and namespace of the symbols. They will be dropped from the final vmlinux and modules because the *(.export_symbol) will go into /DISCARD/ in the linker script. Then, modpost extracts all the information about EXPORT_SYMBOL() from the .export_symbol section, and generates the final C code: KSYMTAB_FUNC(foo, "", ""); KSYMTAB_FUNC(bar, "_gpl", "BAR_NAMESPACE"); KSYMTAB_FUNC() (or KSYMTAB_DATA() if it is data) is expanded to struct kernel_symbol that will be linked to the vmlinux or a module. With this change, EXPORT_SYMBOL() works in the same way for *.c and *.S files, providing the following benefits. [1] Deprecate EXPORT_DATA_SYMBOL() In the old days, EXPORT_SYMBOL() was only available in C files. To export a symbol in *.S, EXPORT_SYMBOL() was placed in a separate *.c file. arch/arm/kernel/armksyms.c is one example written in the classic manner. Commit 22823ab419d8 ("EXPORT_SYMBOL() for asm") removed this limitation. Since then, EXPORT_SYMBOL() can be placed close to the symbol definition in *.S files. It was a nice improvement. However, as that commit mentioned, you need to use EXPORT_DATA_SYMBOL() for data objects on some architectures. In the new approach, modpost checks symbol's type (STT_FUNC or not), and outputs KSYMTAB_FUNC() or KSYMTAB_DATA() accordingly. There are only two users of EXPORT_DATA_SYMBOL: EXPORT_DATA_SYMBOL_GPL(empty_zero_page) (arch/ia64/kernel/head.S) EXPORT_DATA_SYMBOL(ia64_ivt) (arch/ia64/kernel/ivt.S) They are transformed as follows and output into .vmlinux.export.c KSYMTAB_DATA(empty_zero_page, "_gpl", ""); KSYMTAB_DATA(ia64_ivt, "", ""); The other EXPORT_SYMBOL users in ia64 assembly are output as KSYMTAB_FUNC(). EXPORT_DATA_SYMBOL() is now deprecated. [2] merge <linux/export.h> and <asm-generic/export.h> There are two similar header implementations: include/linux/export.h for .c files include/asm-generic/export.h for .S files Ideally, the functionality should be consistent between them, but they tend to diverge. Commit 8651ec01daed ("module: add support for symbol namespaces.") did not support the namespace for *.S files. This commit shifts the essential implementation part to C, which supports EXPORT_SYMBOL_NS() for *.S files. <asm/export.h> and <asm-generic/export.h> will remain as a wrapper of <linux/export.h> for a while. They will be removed after #include <asm/export.h> directives are all replaced with #include <linux/export.h>. [3] Implement CONFIG_TRIM_UNUSED_KSYMS in one-pass algorithm (by a later commit) When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses the directory tree to determine which EXPORT_SYMBOL to trim. If an EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the second traverse, where some source files are recompiled with their EXPORT_SYMBOL() tuned into a no-op. We can do this better now; modpost can selectively emit KSYMTAB entries that are really used by modules. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-11 15:50:52 +00:00
$(NM) $@ | sed -n 's/.* __export_symbol_\(.*\)/EXPORT_SYMBOL(\1);/p' ; } | \
$(CPP) -D__GENKSYMS__ $(c_flags) -xc - | $(genksyms)
quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null
$(obj)/%.symtypes : $(src)/%.S FORCE
$(call cmd,cc_symtypes_S)
quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
cmd_cpp_s_S = $(CPP) $(a_flags) -o $@ $<
$(obj)/%.s: $(src)/%.S FORCE
$(call if_changed_dep,cpp_s_S)
quiet_cmd_as_o_S = AS $(quiet_modtag) $@
cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
ifdef CONFIG_ASM_MODVERSIONS
# versioning matches the C process described above, with difference that
# we parse asm-prototypes.h C header to get function definitions.
cmd_gen_symversions_S = $(call gen_symversions,S)
endif
$(obj)/%.o: $(src)/%.S FORCE
$(call if_changed_rule,as_o_S)
targets += $(filter-out $(subdir-builtin), $(real-obj-y))
targets += $(filter-out $(subdir-modorder), $(real-obj-m))
targets += $(real-dtb-y) $(lib-y) $(always-y)
# Linker scripts preprocessor (.lds.S -> .lds)
# ---------------------------------------------------------------------------
quiet_cmd_cpp_lds_S = LDS $@
cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
-D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
$(obj)/%.lds: $(src)/%.lds.S FORCE
$(call if_changed_dep,cpp_lds_S)
# ASN.1 grammar
# ---------------------------------------------------------------------------
quiet_cmd_asn1_compiler = ASN.1 $(basename $@).[ch]
cmd_asn1_compiler = $(objtree)/scripts/asn1_compiler $< \
$(basename $@).c $(basename $@).h
$(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
$(call cmd,asn1_compiler)
# Build the compiled-in targets
# ---------------------------------------------------------------------------
# To build objects in subdirs, we need to descend into the directories
$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
#
# Rule to compile a set of .o files into one .a file (without symbol table)
#
# To make this rule robust against "Argument list too long" error,
# remove $(obj)/ prefix, and restore it by a shell command.
kbuild: allow architectures to use thin archives instead of ld -r ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-08-24 12:29:19 +00:00
quiet_cmd_ar_builtin = AR $@
cmd_ar_builtin = rm -f $@; \
$(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) | xargs) \
$(AR) cDPrST $@
$(obj)/built-in.a: $(real-obj-y) FORCE
$(call if_changed,ar_builtin)
#
# Rule to create modules.order file
#
# Create commands to either record .ko file or cat modules.order from
# a subdirectory
# Add $(obj-m) as the prerequisite to avoid updating the timestamp of
# modules.order unless contained modules are updated.
cmd_modules_order = { $(foreach m, $(real-prereqs), \
$(if $(filter %/modules.order, $m), cat $m, echo $m);) :; } \
> $@
$(obj)/modules.order: $(obj-m) FORCE
$(call if_changed,modules_order)
#
# Rule to compile a set of .o files into one .a file (with symbol table)
#
$(obj)/lib.a: $(lib-y) FORCE
$(call if_changed,ar)
quiet_cmd_ld_multi_m = LD [M] $@
cmd_ld_multi_m = $(LD) $(ld_flags) -r -o $@ @$< $(cmd_objtool)
define rule_ld_multi_m
$(call cmd_and_savecmd,ld_multi_m)
$(call cmd,gen_objtooldep)
endef
kbuild: do not create *.prelink.o for Clang LTO or IBT When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created for each module. Also, objtool is postponed until LLVM IR is converted to ELF. CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until objects are merged together. This commit stops generating *.prelink.o, so the build flow will look similar with/without LTO. The following figures show how the LTO build currently works, and how this commit is changing it. Current build flow ================== [1] single-object module $(LD) $(CC) +objtool $(LD) foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko (LLVM IR) (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module $(LD) $(CC) $(AR) +objtool $(LD) foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko | (archive) (ELF) | (ELF) foo2.c -----> foo2.o --/ | (LLVM IR) foo.mod.o --/ (LLVM IR) One confusion is that foo.o in multi-object module is an archive despite of its suffix. New build flow ============== [1] single-object module Since there is only one object, there is no need to keep the LLVM IR. Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO is disabled, $(LD) is unneeded because $(CC) produces an ELF object. $(CC)+$(LD)+objtool $(LD) foo.c ----------------------------> foo.o ---------> foo.ko (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module Previously, $(AR) was used to combine LLVM IR files into an archive, but there was no technical reason to do so. Use $(LD) to merge them into a single ELF object. $(LD) $(CC) +objtool $(LD) foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko | (ELF) | (ELF) foo2.c ---------> foo2.o ----/ | (LLVM IR) foo.mod.o --/ (LLVM IR) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64) Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
2022-05-27 10:01:49 +00:00
$(multi-obj-m): objtool-enabled := $(delay-objtool)
$(multi-obj-m): part-of-module := y
$(multi-obj-m): %.o: %.mod FORCE
$(call if_changed_rule,ld_multi_m)
$(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
# Add intermediate targets:
# When building objects with specific suffix patterns, add intermediate
# targets that the final targets are derived from.
intermediate_targets = $(foreach sfx, $(2), \
$(patsubst %$(strip $(1)),%$(sfx), \
$(filter %$(strip $(1)), $(targets))))
kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers GNU Make automatically deletes intermediate files that are updated in a chain of pattern rules. Example 1) %.dtb.o <- %.dtb.S <- %.dtb <- %.dts Example 2) %.o <- %.c <- %.c_shipped A couple of makefiles mark such targets as .PRECIOUS to prevent Make from deleting them, but the correct way is to use .SECONDARY. .SECONDARY Prerequisites of this special target are treated as intermediate files but are never automatically deleted. .PRECIOUS When make is interrupted during execution, it may delete the target file it is updating if the file was modified since make started. If you mark the file as precious, make will never delete the file if interrupted. Both can avoid deletion of intermediate files, but the difference is the behavior when Make is interrupted; .SECONDARY deletes the target, but .PRECIOUS does not. The use of .PRECIOUS is relatively rare since we do not want to keep partially constructed (possibly corrupted) targets. Another difference is that .PRECIOUS works with pattern rules whereas .SECONDARY does not. .PRECIOUS: $(obj)/%.lex.c works, but .SECONDARY: $(obj)/%.lex.c has no effect. However, for the reason above, I do not want to use .PRECIOUS which could cause obscure build breakage. The targets specified as .SECONDARY must be explicit. $(targets) contains all targets that need to include .*.cmd files. So, the intermediates you want to keep are mostly in there. Therefore, mark $(targets) as .SECONDARY. It means primary targets are also marked as .SECONDARY, but I do not see any drawback for this. I replaced some .SECONDARY / .PRECIOUS markers with 'targets'. This will make Kbuild search for non-existing .*.cmd files, but this is not a noticeable performance issue. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Frank Rowand <frowand.list@gmail.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-03-23 13:04:39 +00:00
# %.asn1.o <- %.asn1.[ch] <- %.asn1
# %.dtb.o <- %.dtb.S <- %.dtb <- %.dts
# %.dtbo.o <- %.dtbo.S <- %.dtbo <- %.dtso
# %.lex.o <- %.lex.c <- %.l
# %.tab.o <- %.tab.[ch] <- %.y
kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers GNU Make automatically deletes intermediate files that are updated in a chain of pattern rules. Example 1) %.dtb.o <- %.dtb.S <- %.dtb <- %.dts Example 2) %.o <- %.c <- %.c_shipped A couple of makefiles mark such targets as .PRECIOUS to prevent Make from deleting them, but the correct way is to use .SECONDARY. .SECONDARY Prerequisites of this special target are treated as intermediate files but are never automatically deleted. .PRECIOUS When make is interrupted during execution, it may delete the target file it is updating if the file was modified since make started. If you mark the file as precious, make will never delete the file if interrupted. Both can avoid deletion of intermediate files, but the difference is the behavior when Make is interrupted; .SECONDARY deletes the target, but .PRECIOUS does not. The use of .PRECIOUS is relatively rare since we do not want to keep partially constructed (possibly corrupted) targets. Another difference is that .PRECIOUS works with pattern rules whereas .SECONDARY does not. .PRECIOUS: $(obj)/%.lex.c works, but .SECONDARY: $(obj)/%.lex.c has no effect. However, for the reason above, I do not want to use .PRECIOUS which could cause obscure build breakage. The targets specified as .SECONDARY must be explicit. $(targets) contains all targets that need to include .*.cmd files. So, the intermediates you want to keep are mostly in there. Therefore, mark $(targets) as .SECONDARY. It means primary targets are also marked as .SECONDARY, but I do not see any drawback for this. I replaced some .SECONDARY / .PRECIOUS markers with 'targets'. This will make Kbuild search for non-existing .*.cmd files, but this is not a noticeable performance issue. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Frank Rowand <frowand.list@gmail.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-03-23 13:04:39 +00:00
targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
$(call intermediate_targets, .dtb.o, .dtb.S .dtb) \
$(call intermediate_targets, .dtbo.o, .dtbo.S .dtbo) \
$(call intermediate_targets, .lex.o, .lex.c) \
$(call intermediate_targets, .tab.o, .tab.c .tab.h)
kbuild: make single targets work more correctly Currently, the single target build directly descends into the directory of the target. For example, $ make foo/bar/baz.o ... directly descends into foo/bar/. On the other hand, the normal build usually descends one directory at a time, i.e. descends into foo/, and then foo/bar/. This difference causes some problems. [1] miss subdir-asflags-y, subdir-ccflags-y in upper Makefiles The options in subdir-{as,cc}flags-y take effect in the current and its sub-directories. In other words, they are inherited downward. In the example above, the single target will miss subdir-{as,cc}flags-y if they are defined in foo/Makefile. [2] could be built in a different directory As Documentation/kbuild/modules.rst section 4.3 says, Kbuild can handle files that are spread over several sub-directories. The build rule of foo/bar/baz.o may not necessarily be specified in foo/bar/Makefile. It might be specifies in foo/Makefile as follows: [foo/Makefile] obj-y := bar/baz.o This often happens when a module is so big that its source files are divided into sub-directories. In this case, there is no Makefile in the foo/bar/ directory, yet the single target descends into foo/bar/, then fails due to the missing Makefile. You can still do 'make foo/bar/' for partial building, but cannot do 'make foo/bar/baz.s'. I believe the single target '%.s' is a useful feature for inspecting the compiler output. Some modules work around this issue by putting an empty Makefile in every sub-directory. This commit fixes those problems by making the single target build descend in the same way as the normal build does. Another change is the single target build will observe the CONFIG options. Previously, it allowed users to build the foo.o even when the corresponding CONFIG_FOO is disabled: obj-$(CONFIG_FOO) += foo.o In the new behavior, the single target build will just fail and show "No rule to make target ..." (or "Nothing to be done for ..." if the stale object already exists, but cannot be updated). The disadvantage of this commit is the build speed. Now that the single target build visits every directory and parses lots of Makefiles, it is slower than before. (But, I hope it will not be too slow.) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14 15:19:18 +00:00
# Build
# ---------------------------------------------------------------------------
$(obj)/: $(if $(KBUILD_BUILTIN), $(targets-for-builtin)) \
$(if $(KBUILD_MODULES), $(targets-for-modules)) \
$(subdir-ym) $(always-y)
kbuild: make single targets work more correctly Currently, the single target build directly descends into the directory of the target. For example, $ make foo/bar/baz.o ... directly descends into foo/bar/. On the other hand, the normal build usually descends one directory at a time, i.e. descends into foo/, and then foo/bar/. This difference causes some problems. [1] miss subdir-asflags-y, subdir-ccflags-y in upper Makefiles The options in subdir-{as,cc}flags-y take effect in the current and its sub-directories. In other words, they are inherited downward. In the example above, the single target will miss subdir-{as,cc}flags-y if they are defined in foo/Makefile. [2] could be built in a different directory As Documentation/kbuild/modules.rst section 4.3 says, Kbuild can handle files that are spread over several sub-directories. The build rule of foo/bar/baz.o may not necessarily be specified in foo/bar/Makefile. It might be specifies in foo/Makefile as follows: [foo/Makefile] obj-y := bar/baz.o This often happens when a module is so big that its source files are divided into sub-directories. In this case, there is no Makefile in the foo/bar/ directory, yet the single target descends into foo/bar/, then fails due to the missing Makefile. You can still do 'make foo/bar/' for partial building, but cannot do 'make foo/bar/baz.s'. I believe the single target '%.s' is a useful feature for inspecting the compiler output. Some modules work around this issue by putting an empty Makefile in every sub-directory. This commit fixes those problems by making the single target build descend in the same way as the normal build does. Another change is the single target build will observe the CONFIG options. Previously, it allowed users to build the foo.o even when the corresponding CONFIG_FOO is disabled: obj-$(CONFIG_FOO) += foo.o In the new behavior, the single target build will just fail and show "No rule to make target ..." (or "Nothing to be done for ..." if the stale object already exists, but cannot be updated). The disadvantage of this commit is the build speed. Now that the single target build visits every directory and parses lots of Makefiles, it is slower than before. (But, I hope it will not be too slow.) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14 15:19:18 +00:00
@:
# Single targets
# ---------------------------------------------------------------------------
kbuild: make single targets work more correctly Currently, the single target build directly descends into the directory of the target. For example, $ make foo/bar/baz.o ... directly descends into foo/bar/. On the other hand, the normal build usually descends one directory at a time, i.e. descends into foo/, and then foo/bar/. This difference causes some problems. [1] miss subdir-asflags-y, subdir-ccflags-y in upper Makefiles The options in subdir-{as,cc}flags-y take effect in the current and its sub-directories. In other words, they are inherited downward. In the example above, the single target will miss subdir-{as,cc}flags-y if they are defined in foo/Makefile. [2] could be built in a different directory As Documentation/kbuild/modules.rst section 4.3 says, Kbuild can handle files that are spread over several sub-directories. The build rule of foo/bar/baz.o may not necessarily be specified in foo/bar/Makefile. It might be specifies in foo/Makefile as follows: [foo/Makefile] obj-y := bar/baz.o This often happens when a module is so big that its source files are divided into sub-directories. In this case, there is no Makefile in the foo/bar/ directory, yet the single target descends into foo/bar/, then fails due to the missing Makefile. You can still do 'make foo/bar/' for partial building, but cannot do 'make foo/bar/baz.s'. I believe the single target '%.s' is a useful feature for inspecting the compiler output. Some modules work around this issue by putting an empty Makefile in every sub-directory. This commit fixes those problems by making the single target build descend in the same way as the normal build does. Another change is the single target build will observe the CONFIG options. Previously, it allowed users to build the foo.o even when the corresponding CONFIG_FOO is disabled: obj-$(CONFIG_FOO) += foo.o In the new behavior, the single target build will just fail and show "No rule to make target ..." (or "Nothing to be done for ..." if the stale object already exists, but cannot be updated). The disadvantage of this commit is the build speed. Now that the single target build visits every directory and parses lots of Makefiles, it is slower than before. (But, I hope it will not be too slow.) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14 15:19:18 +00:00
single-subdirs := $(foreach d, $(subdir-ym), $(if $(filter $d/%, $(MAKECMDGOALS)), $d))
single-subdir-goals := $(filter $(addsuffix /%, $(single-subdirs)), $(MAKECMDGOALS))
kbuild: make single targets work more correctly Currently, the single target build directly descends into the directory of the target. For example, $ make foo/bar/baz.o ... directly descends into foo/bar/. On the other hand, the normal build usually descends one directory at a time, i.e. descends into foo/, and then foo/bar/. This difference causes some problems. [1] miss subdir-asflags-y, subdir-ccflags-y in upper Makefiles The options in subdir-{as,cc}flags-y take effect in the current and its sub-directories. In other words, they are inherited downward. In the example above, the single target will miss subdir-{as,cc}flags-y if they are defined in foo/Makefile. [2] could be built in a different directory As Documentation/kbuild/modules.rst section 4.3 says, Kbuild can handle files that are spread over several sub-directories. The build rule of foo/bar/baz.o may not necessarily be specified in foo/bar/Makefile. It might be specifies in foo/Makefile as follows: [foo/Makefile] obj-y := bar/baz.o This often happens when a module is so big that its source files are divided into sub-directories. In this case, there is no Makefile in the foo/bar/ directory, yet the single target descends into foo/bar/, then fails due to the missing Makefile. You can still do 'make foo/bar/' for partial building, but cannot do 'make foo/bar/baz.s'. I believe the single target '%.s' is a useful feature for inspecting the compiler output. Some modules work around this issue by putting an empty Makefile in every sub-directory. This commit fixes those problems by making the single target build descend in the same way as the normal build does. Another change is the single target build will observe the CONFIG options. Previously, it allowed users to build the foo.o even when the corresponding CONFIG_FOO is disabled: obj-$(CONFIG_FOO) += foo.o In the new behavior, the single target build will just fail and show "No rule to make target ..." (or "Nothing to be done for ..." if the stale object already exists, but cannot be updated). The disadvantage of this commit is the build speed. Now that the single target build visits every directory and parses lots of Makefiles, it is slower than before. (But, I hope it will not be too slow.) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14 15:19:18 +00:00
$(single-subdir-goals): $(single-subdirs)
kbuild: make single targets work more correctly Currently, the single target build directly descends into the directory of the target. For example, $ make foo/bar/baz.o ... directly descends into foo/bar/. On the other hand, the normal build usually descends one directory at a time, i.e. descends into foo/, and then foo/bar/. This difference causes some problems. [1] miss subdir-asflags-y, subdir-ccflags-y in upper Makefiles The options in subdir-{as,cc}flags-y take effect in the current and its sub-directories. In other words, they are inherited downward. In the example above, the single target will miss subdir-{as,cc}flags-y if they are defined in foo/Makefile. [2] could be built in a different directory As Documentation/kbuild/modules.rst section 4.3 says, Kbuild can handle files that are spread over several sub-directories. The build rule of foo/bar/baz.o may not necessarily be specified in foo/bar/Makefile. It might be specifies in foo/Makefile as follows: [foo/Makefile] obj-y := bar/baz.o This often happens when a module is so big that its source files are divided into sub-directories. In this case, there is no Makefile in the foo/bar/ directory, yet the single target descends into foo/bar/, then fails due to the missing Makefile. You can still do 'make foo/bar/' for partial building, but cannot do 'make foo/bar/baz.s'. I believe the single target '%.s' is a useful feature for inspecting the compiler output. Some modules work around this issue by putting an empty Makefile in every sub-directory. This commit fixes those problems by making the single target build descend in the same way as the normal build does. Another change is the single target build will observe the CONFIG options. Previously, it allowed users to build the foo.o even when the corresponding CONFIG_FOO is disabled: obj-$(CONFIG_FOO) += foo.o In the new behavior, the single target build will just fail and show "No rule to make target ..." (or "Nothing to be done for ..." if the stale object already exists, but cannot be updated). The disadvantage of this commit is the build speed. Now that the single target build visits every directory and parses lots of Makefiles, it is slower than before. (But, I hope it will not be too slow.) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14 15:19:18 +00:00
@:
# Descending
# ---------------------------------------------------------------------------
PHONY += $(subdir-ym)
$(subdir-ym):
$(Q)$(MAKE) $(build)=$@ \
need-builtin=$(if $(filter $@/built-in.a, $(subdir-builtin)),1) \
need-modorder=$(if $(filter $@/modules.order, $(subdir-modorder)),1) \
$(filter $@/%, $(single-subdir-goals))
# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------
PHONY += FORCE
FORCE:
targets += $(filter-out $(single-subdir-goals), $(MAKECMDGOALS))
targets := $(filter-out $(PHONY), $(targets))
# Read all saved command lines and dependencies for the $(targets) we
# may be building above, using $(if_changed{,_dep}). As an
# optimization, we don't need to read them if the target does not
# exist, we will rebuild anyway in that case.
kbuild: let fixdep directly write to .*.cmd files Currently, fixdep writes dependencies to .*.tmp, which is renamed to .*.cmd after everything succeeds. This is a very safe way to avoid corrupted .*.cmd files. The if_changed_dep has carried this safety mechanism since it was added in 2002. If fixdep fails for some reasons or a user terminates the build while fixdep is running, the incomplete output from the fixdep could be troublesome. This is my insight about some bad scenarios: [1] If the compiler succeeds to generate *.o file, but fixdep fails to write necessary dependencies to .*.cmd file, Make will miss to rebuild the object when headers or CONFIG options are changed. In this case, fixdep should not generate .*.cmd file at all so that 'arg-check' will surely trigger the rebuild of the object. [2] A partially constructed .*.cmd file may not be a syntactically correct makefile. The next time Make runs, it would include it, then fail to parse it. Once this happens, 'make clean' is be the only way to fix it. In fact, [1] is no longer a problem since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special target"). Make deletes a target file on any failure in its recipe. Because fixdep is a part of the recipe of *.o target, if it fails, the *.o is deleted anyway. However, I am a bit worried about the slight possibility of [2]. So, here is a solution. Let fixdep directly write to a .*.cmd file, but allow makefiles to include it only when its corresponding target exists. This effectively reverts commit 2982c953570b ("kbuild: remove redundant $(wildcard ...) for cmd_files calculation"), and commit 00d78ab2ba75 ("kbuild: remove dead code in cmd_files calculation in top Makefile") because now we must check the presence of targets. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-11-30 01:05:22 +00:00
existing-targets := $(wildcard $(sort $(targets)))
kbuild: let fixdep directly write to .*.cmd files Currently, fixdep writes dependencies to .*.tmp, which is renamed to .*.cmd after everything succeeds. This is a very safe way to avoid corrupted .*.cmd files. The if_changed_dep has carried this safety mechanism since it was added in 2002. If fixdep fails for some reasons or a user terminates the build while fixdep is running, the incomplete output from the fixdep could be troublesome. This is my insight about some bad scenarios: [1] If the compiler succeeds to generate *.o file, but fixdep fails to write necessary dependencies to .*.cmd file, Make will miss to rebuild the object when headers or CONFIG options are changed. In this case, fixdep should not generate .*.cmd file at all so that 'arg-check' will surely trigger the rebuild of the object. [2] A partially constructed .*.cmd file may not be a syntactically correct makefile. The next time Make runs, it would include it, then fail to parse it. Once this happens, 'make clean' is be the only way to fix it. In fact, [1] is no longer a problem since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special target"). Make deletes a target file on any failure in its recipe. Because fixdep is a part of the recipe of *.o target, if it fails, the *.o is deleted anyway. However, I am a bit worried about the slight possibility of [2]. So, here is a solution. Let fixdep directly write to a .*.cmd file, but allow makefiles to include it only when its corresponding target exists. This effectively reverts commit 2982c953570b ("kbuild: remove redundant $(wildcard ...) for cmd_files calculation"), and commit 00d78ab2ba75 ("kbuild: remove dead code in cmd_files calculation in top Makefile") because now we must check the presence of targets. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-11-30 01:05:22 +00:00
-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
# Create directories for object files if they do not exist
obj-dirs := $(sort $(patsubst %/,%, $(dir $(targets))))
kbuild: let fixdep directly write to .*.cmd files Currently, fixdep writes dependencies to .*.tmp, which is renamed to .*.cmd after everything succeeds. This is a very safe way to avoid corrupted .*.cmd files. The if_changed_dep has carried this safety mechanism since it was added in 2002. If fixdep fails for some reasons or a user terminates the build while fixdep is running, the incomplete output from the fixdep could be troublesome. This is my insight about some bad scenarios: [1] If the compiler succeeds to generate *.o file, but fixdep fails to write necessary dependencies to .*.cmd file, Make will miss to rebuild the object when headers or CONFIG options are changed. In this case, fixdep should not generate .*.cmd file at all so that 'arg-check' will surely trigger the rebuild of the object. [2] A partially constructed .*.cmd file may not be a syntactically correct makefile. The next time Make runs, it would include it, then fail to parse it. Once this happens, 'make clean' is be the only way to fix it. In fact, [1] is no longer a problem since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special target"). Make deletes a target file on any failure in its recipe. Because fixdep is a part of the recipe of *.o target, if it fails, the *.o is deleted anyway. However, I am a bit worried about the slight possibility of [2]. So, here is a solution. Let fixdep directly write to a .*.cmd file, but allow makefiles to include it only when its corresponding target exists. This effectively reverts commit 2982c953570b ("kbuild: remove redundant $(wildcard ...) for cmd_files calculation"), and commit 00d78ab2ba75 ("kbuild: remove dead code in cmd_files calculation in top Makefile") because now we must check the presence of targets. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-11-30 01:05:22 +00:00
# If targets exist, their directories apparently exist. Skip mkdir.
existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
ifneq ($(obj-dirs),)
$(shell mkdir -p $(obj-dirs))
endif
.PHONY: $(PHONY)