Commit bc081dd6e9 ("kbuild: generate modules.builtin") added
infrastructure to generate modules.builtin, the list of all
builtin modules.
Basically, it works like this:
- Kconfig generates include/config/tristate.conf, the list of
tristate CONFIG options with a value in a capital letter.
- scripts/Makefile.modbuiltin makes Kbuild descend into
directories to collect the information of builtin modules.
I am not a big fan of it because Kbuild ends up with traversing
the source tree twice.
I am not sure how perfectly it should work, but this approach cannot
avoid false positives; even if the relevant CONFIG option is tristate,
some Makefiles forces obj-m to obj-y.
Some examples are:
arch/powerpc/platforms/powermac/Makefile:
obj-$(CONFIG_NVRAM:m=y) += nvram.o
net/ipv6/Makefile:
obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o
net/netlabel/Makefile:
obj-$(subst m,y,$(CONFIG_IPV6)) += netlabel_calipso.o
Nobody has complained about (or noticed) it, so it is probably fine to
have false positives in modules.builtin.
This commit simplifies the implementation. Let's exploit the fact
that every module has MODULE_LICENSE(). (modpost shows a warning if
MODULE_LICENSE is missing. If so, 0-day bot would already have blocked
such a module.)
I added MODULE_FILE to <linux/module.h>. When the code is being compiled
as builtin, it will be filled with the file path of the module, and
collected into modules.builtin.info. Then, scripts/link-vmlinux.sh
extracts the list of builtin modules out of it.
This new approach fixes the false-positives above, but adds another
type of false-positives; non-modular code may have MODULE_LICENSE()
by mistake. This is not a big deal, it is just the code is always
orphan. We can clean it up if we like. You can see cleanup examples by:
$ git log --grep='make.* explicitly non-modular'
To sum up, this commits deletes lots of code, but still produces almost
equivalent results. Please note it does not increase the vmlinux size at
all. As you can see in include/asm-generic/vmlinux.lds.h, the .modinfo
section is discarded in the link stage.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
- fix warning in out-of-tree 'make clean'
- add READELF variable to the top Makefile
- fix broken builds when LINUX_COMPILE_BY contains a backslash
- fix build warning in kallsyms
- fix NULL pointer access in expr_eq() in Kconfig
- fix missing dependency on rsync in deb-pkg build
- remove ---help--- from documentation
- fix misleading documentation about directory descending
-----BEGIN PGP SIGNATURE-----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=OKOu
-----END PGP SIGNATURE-----
Merge tag 'kbuild-fixes-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild fixes from Masahiro Yamada:
- fix warning in out-of-tree 'make clean'
- add READELF variable to the top Makefile
- fix broken builds when LINUX_COMPILE_BY contains a backslash
- fix build warning in kallsyms
- fix NULL pointer access in expr_eq() in Kconfig
- fix missing dependency on rsync in deb-pkg build
- remove ---help--- from documentation
- fix misleading documentation about directory descending
* tag 'kbuild-fixes-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: clarify the difference between obj-y and obj-m w.r.t. descending
kconfig: remove ---help--- from documentation
scripts: package: mkdebian: add missing rsync dependency
kconfig: don't crash on NULL expressions in expr_eq()
scripts/kallsyms: fix offset overflow of kallsyms_relative_base
mkcompile_h: use printf for LINUX_COMPILE_BY
mkcompile_h: git rid of UTS_TRUNCATE from LINUX_COMPILE_{BY,HOST}
x86/boot: kbuild: allow readelf executable to be specified
kbuild: fix 'No such file or directory' warning when cleaning
Introduce a new READELF variable to top-level Makefile, so the name of
readelf binary can be specified.
Before this change the name of the binary was hardcoded to
"$(CROSS_COMPILE)readelf" which might not be present for every
toolchain.
This allows to build with LLVM Object Reader by using make parameter
READELF=llvm-readelf.
Link: https://github.com/ClangBuiltLinux/linux/issues/771
Signed-off-by: Dmitry Golovin <dima@golovin.in>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
- remove unneeded asm headers from hexagon, ia64
- add 'dir-pkg' target, which works like 'tar-pkg' but skips archiving
- add 'helpnewconfig' target, which shows help for new CONFIG options
- support 'make nsdeps' for external modules
- make rebuilds faster by deleting $(wildcard $^) checks
- remove compile tests for kernel-space headers
- refactor modpost to simplify modversion handling
- make single target builds faster
- optimize and clean up scripts/kallsyms.c
- refactor various Makefiles and scripts
-----BEGIN PGP SIGNATURE-----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=zUaB
-----END PGP SIGNATURE-----
Merge tag 'kbuild-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- remove unneeded asm headers from hexagon, ia64
- add 'dir-pkg' target, which works like 'tar-pkg' but skips archiving
- add 'helpnewconfig' target, which shows help for new CONFIG options
- support 'make nsdeps' for external modules
- make rebuilds faster by deleting $(wildcard $^) checks
- remove compile tests for kernel-space headers
- refactor modpost to simplify modversion handling
- make single target builds faster
- optimize and clean up scripts/kallsyms.c
- refactor various Makefiles and scripts
* tag 'kbuild-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (59 commits)
MAINTAINERS: update Kbuild/Kconfig maintainer's email address
scripts/kallsyms: remove redundant initializers
scripts/kallsyms: put check_symbol_range() calls close together
scripts/kallsyms: make check_symbol_range() void function
scripts/kallsyms: move ignored symbol types to is_ignored_symbol()
scripts/kallsyms: move more patterns to the ignored_prefixes array
scripts/kallsyms: skip ignored symbols very early
scripts/kallsyms: add const qualifiers where possible
scripts/kallsyms: make find_token() return (unsigned char *)
scripts/kallsyms: replace prefix_underscores_count() with strspn()
scripts/kallsyms: add sym_name() to mitigate cast ugliness
scripts/kallsyms: remove unneeded length check for prefix matching
scripts/kallsyms: remove redundant is_arm_mapping_symbol()
scripts/kallsyms: set relative_base more effectively
scripts/kallsyms: shrink table before sorting it
scripts/kallsyms: fix definitely-lost memory leak
scripts/kallsyms: remove unneeded #ifndef ARRAY_SIZE
kbuild: make single target builds even faster
modpost: respect the previous export when 'exported twice' is warned
modpost: do not set ->preloaded for symbols from Module.symvers
...
Commit 2dffd23f81 ("kbuild: make single target builds much faster")
made the situation much better.
To improve it even more, apply the similar idea to the top Makefile.
Trim unrelated directories from build-dirs.
The single build code must be moved above the 'descend' target.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Jens Axboe <axboe@kernel.dk>
Currently, some sanity checks for uapi headers are done by
scripts/headers_check.pl, which is wired up to the 'headers_check'
target in the top Makefile.
It is true compiling headers has better test coverage, but there
are still several headers excluded from the compile test. I like
to keep headers_check.pl for a while, but we can delete a lot of
code by moving the build rule to usr/include/Makefile.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
There are both positive and negative options about this feature.
At first, I thought it was a good idea, but actually Linus stated a
negative opinion (https://lkml.org/lkml/2019/9/29/227). I admit it
is ugly and annoying.
The baseline I'd like to keep is the compile-test of uapi headers.
(Otherwise, kernel developers have no way to ensure the correctness
of the exported headers.)
I will maintain a small build rule in usr/include/Makefile.
Remove the other header test functionality.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Sparse uses the same executable for all archs and uses flags
like -m64, -mbig-endian or -D__arm__ for arch-specific parameters.
But Sparse also uses value from the host machine used to build
Sparse as default value for the target machine.
This works, of course, well for native build but can create
problems when cross-compiling, like defining both '__i386__'
and '__arm__' when cross-compiling for arm on a x86-64 machine.
Fix this by explicitely telling sparse the target architecture.
Reported-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
scripts/nsdeps is written to take care of only in-tree modules.
Perhaps, this is not a bug, but just a design. At least,
Documentation/core-api/symbol-namespaces.rst focuses on in-tree modules.
Having said that, some people already tried nsdeps for external modules.
So, it would be nice to support it.
Reported-by: Steve French <smfrench@gmail.com>
Reported-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Reviewed-by: Matthias Maennich <maennich@google.com>
Tested-by: Matthias Maennich <maennich@google.com>
The modpost, with the -d option given, generates per-module .ns_deps
files.
Kbuild generates per-module .mod files to carry module information.
This is convenient because Make handles multiple jobs in parallel
when the -j option is given.
On the other hand, the modpost always runs as a single thread.
I do not see a strong reason to produce separate .ns_deps files.
This commit changes the modpost to generate just one file,
modules.nsdeps, each line of which has the following format:
<module_name>: <list of missing namespaces>
Please note it contains *missing* namespaces instead of required ones.
So, modules.nsdeps is empty if the namespace dependency is all good.
This will work more efficiently because spatch will no longer process
already imported namespaces. I removed the '(if needed)' from the
nsdeps log since spatch is invoked only when needed.
This also solves the stale .ns_deps problem reported by Jessica Yu:
https://lkml.org/lkml/2019/10/28/467
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Reviewed-by: Matthias Maennich <maennich@google.com>
Tested-by: Matthias Maennich <maennich@google.com>
'make nsdeps' invokes the modpost three times at most; before linking
vmlinux, before building modules, and finally for generating .ns_deps
files. Running the modpost again and again is not efficient.
The last two can be unified. When the -d option is given, the modpost
still does the usual job, and in addition, generates .ns_deps files.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Matthias Maennich <maennich@google.com>
Reviewed-by: Matthias Maennich <maennich@google.com>
There are 6 defconfigs with names longer than 24 characters, breaking
alignment in "make help".
The "winner" is "ecovec24-romimage_defconfig", counting in at 27
characters.
Extend the defconfig field size to 27 to restore alignment.
Don't use a larger value, to not encourage people to create even longer
defconfig names.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Some "make help" text lines extend beyond 80 characters.
Wrap them before an opening parenthesis, or before 80 characters.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
When single-build is set, everything in $(MAKECMDGOALS) is a single
target. You can use $(MAKECMDGOALS) to list out the single targets.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
- Fix broken external module builds due to a modpost bug in read_dump(),
where the namespace was not being strdup'd and sym->namespace would be
set to bogus data.
- Various namespace-related kbuild fixes and cleanups thanks to
Masahiro Yamada.
Signed-off-by: Jessica Yu <jeyu@kernel.org>
-----BEGIN PGP SIGNATURE-----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=Ebck
-----END PGP SIGNATURE-----
Merge tag 'modules-for-v5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
Pull module fixes from Jessica Yu:
"Code cleanups and kbuild/namespace related fixups from Masahiro.
Most importantly, it fixes a namespace-related modpost issue for
external module builds
- Fix broken external module builds due to a modpost bug in
read_dump(), where the namespace was not being strdup'd and
sym->namespace would be set to bogus data.
- Various namespace-related kbuild fixes and cleanups thanks to
Masahiro Yamada"
* tag 'modules-for-v5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
doc: move namespaces.rst from kbuild/ to core-api/
nsdeps: make generated patches independent of locale
nsdeps: fix hashbang of scripts/nsdeps
kbuild: fix build error of 'make nsdeps' in clean tree
module: rename __kstrtab_ns_* to __kstrtabns_* to avoid symbol conflict
modpost: fix broken sym->namespace for external module builds
module: swap the order of symbol.namespace
scripts: add_namespace: Fix coccicheck failed
This Kselftest update for Linux 5.4-rc3 consists fixes for existing
tests and the framework. Cristian Marussi's patches add ability to
skip targets (tests) and exclude tests that didn't build from run-list.
These patches improve the Kselftest results. Ability to skip targets
helps avoid running tests that aren't supported in certain environments.
As an example, bpf tests from mainline aren't supported on stable kernels
and have dependency on bleeding edge llvm. Being able to skip bpf on
systems that can't meet this llvm dependency will be helpful.
Kselftest can be built and installed from the main Makefile. This change
help simplify Kselftest use-cases which addresses request from users.
Kees Cook added per test timeout support to limit individual test run-time.
-----BEGIN PGP SIGNATURE-----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=vdrT
-----END PGP SIGNATURE-----
Merge tag 'linux-kselftest-5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
Pull Kselftest fixes from Shuah Khan:
"Fixes for existing tests and the framework.
Cristian Marussi's patches add the ability to skip targets (tests) and
exclude tests that didn't build from run-list. These patches improve
the Kselftest results. Ability to skip targets helps avoid running
tests that aren't supported in certain environments. As an example,
bpf tests from mainline aren't supported on stable kernels and have
dependency on bleeding edge llvm. Being able to skip bpf on systems
that can't meet this llvm dependency will be helpful.
Kselftest can be built and installed from the main Makefile. This
change help simplify Kselftest use-cases which addresses request from
users.
Kees Cook added per test timeout support to limit individual test
run-time"
* tag 'linux-kselftest-5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
selftests: watchdog: Add command line option to show watchdog_info
selftests: watchdog: Validate optional file argument
selftests/kselftest/runner.sh: Add 45 second timeout per test
kselftest: exclude failed TARGETS from runlist
kselftest: add capability to skip chosen TARGETS
selftests: Add kselftest-all and kselftest-install targets
Running 'make nsdeps' in a clean source tree fails as follows:
$ make -s clean; make -s defconfig; make nsdeps
[ snip ]
awk: fatal: cannot open file `init/modules.order' for reading (No such file or directory)
make: *** [Makefile;1307: modules.order] Error 2
make: *** Deleting file 'modules.order'
make: *** Waiting for unfinished jobs....
The cause of the error is 'make nsdeps' does not build modules at all.
Set KBUILD_MODULES to fix it.
Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Add kselftest-all target to build tests from the top level
Makefile. This is to simplify kselftest use-cases for CI and
distributions where build and test systems are different.
Current kselftest target builds and runs tests on a development
system which is a developer use-case.
Add kselftest-install target to install tests from the top level
Makefile. This is to simplify kselftest use-cases for CI and
distributions where build and test systems are different.
This change addresses requests from developers and testers to add
support for installing kselftest from the main Makefile.
In addition, make the install directory the same when install is
run using "make kselftest-install" or by running kselftest_install.sh.
Also fix the INSTALL_PATH variable conflict between main Makefile and
selftests Makefile.
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Commit 40df759e2b ("kbuild: Fix build with binutils <= 2.19")
introduced ar-option and KBUILD_ARFLAGS to deal with old binutils.
According to Documentation/process/changes.rst, the current minimal
supported version of binutils is 2.21 so you can assume the 'D' option
is always supported. Not only GNU ar but also llvm-ar supports it.
With the 'D' option hard-coded, there is no more user of ar-option
or KBUILD_ARFLAGS.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Summary of modules changes for the 5.4 merge window:
- Introduce exported symbol namespaces.
This new feature allows subsystem maintainers to partition and
categorize their exported symbols into explicit namespaces. Module
authors are now required to import the namespaces they need.
Some of the main motivations of this feature include: allowing kernel
developers to better manage the export surface, allow subsystem
maintainers to explicitly state that usage of some exported symbols
should only be limited to certain users (think: inter-module or
inter-driver symbols, debugging symbols, etc), as well as more easily
limiting the availability of namespaced symbols to other parts of the
kernel. With the module import requirement, it is also easier to spot
the misuse of exported symbols during patch review. Two new macros are
introduced: EXPORT_SYMBOL_NS() and EXPORT_SYMBOL_NS_GPL(). The API is
thoroughly documented in Documentation/kbuild/namespaces.rst.
- Some small code and kbuild cleanups here and there.
-----BEGIN PGP SIGNATURE-----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=72Uy
-----END PGP SIGNATURE-----
Merge tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
Pull modules updates from Jessica Yu:
"The main bulk of this pull request introduces a new exported symbol
namespaces feature. The number of exported symbols is increasingly
growing with each release (we're at about 31k exports as of 5.3-rc7)
and we currently have no way of visualizing how these symbols are
"clustered" or making sense of this huge export surface.
Namespacing exported symbols allows kernel developers to more
explicitly partition and categorize exported symbols, as well as more
easily limiting the availability of namespaced symbols to other parts
of the kernel. For starters, we have introduced the USB_STORAGE
namespace to demonstrate the API's usage. I have briefly summarized
the feature and its main motivations in the tag below.
Summary:
- Introduce exported symbol namespaces.
This new feature allows subsystem maintainers to partition and
categorize their exported symbols into explicit namespaces. Module
authors are now required to import the namespaces they need.
Some of the main motivations of this feature include: allowing
kernel developers to better manage the export surface, allow
subsystem maintainers to explicitly state that usage of some
exported symbols should only be limited to certain users (think:
inter-module or inter-driver symbols, debugging symbols, etc), as
well as more easily limiting the availability of namespaced symbols
to other parts of the kernel.
With the module import requirement, it is also easier to spot the
misuse of exported symbols during patch review.
Two new macros are introduced: EXPORT_SYMBOL_NS() and
EXPORT_SYMBOL_NS_GPL(). The API is thoroughly documented in
Documentation/kbuild/namespaces.rst.
- Some small code and kbuild cleanups here and there"
* tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
module: Remove leftover '#undef' from export header
module: remove unneeded casts in cmp_name()
module: move CONFIG_UNUSED_SYMBOLS to the sub-menu of MODULES
module: remove redundant 'depends on MODULES'
module: Fix link failure due to invalid relocation on namespace offset
usb-storage: export symbols in USB_STORAGE namespace
usb-storage: remove single-use define for debugging
docs: Add documentation for Symbol Namespaces
scripts: Coccinelle script for namespace dependencies.
modpost: add support for generating namespace dependencies
export: allow definition default namespaces in Makefiles or sources
module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
modpost: add support for symbol namespaces
module: add support for symbol namespaces.
export: explicitly align struct kernel_symbol
module: support reading multiple values per modinfo tag
- add modpost warn exported symbols marked as 'static' because 'static'
and EXPORT_SYMBOL is an odd combination
- break the build early if gold linker is used
- optimize the Bison rule to produce .c and .h files by a single
pattern rule
- handle PREEMPT_RT in the module vermagic and UTS_VERSION
- warn CONFIG options leaked to the user-space except existing ones
- make single targets work properly
- rebuild modules when module linker scripts are updated
- split the module final link stage into scripts/Makefile.modfinal
- fix the missed error code in merge_config.sh
- improve the error message displayed on the attempt of the O= build
in unclean source tree
- remove 'clean-dirs' syntax
- disable -Wimplicit-fallthrough warning for Clang
- add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC
- remove ARCH_{CPP,A,C}FLAGS variables
- add $(BASH) to run bash scripts
- change *CFLAGS_<basetarget>.o to take the relative path to $(obj)
instead of the basename
- stop suppressing Clang's -Wunused-function warnings when W=1
- fix linux/export.h to avoid genksyms calculating CRC of trimmed
exported symbols
- misc cleanups
-----BEGIN PGP SIGNATURE-----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=VGqV
-----END PGP SIGNATURE-----
Merge tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- add modpost warn exported symbols marked as 'static' because 'static'
and EXPORT_SYMBOL is an odd combination
- break the build early if gold linker is used
- optimize the Bison rule to produce .c and .h files by a single
pattern rule
- handle PREEMPT_RT in the module vermagic and UTS_VERSION
- warn CONFIG options leaked to the user-space except existing ones
- make single targets work properly
- rebuild modules when module linker scripts are updated
- split the module final link stage into scripts/Makefile.modfinal
- fix the missed error code in merge_config.sh
- improve the error message displayed on the attempt of the O= build in
unclean source tree
- remove 'clean-dirs' syntax
- disable -Wimplicit-fallthrough warning for Clang
- add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC
- remove ARCH_{CPP,A,C}FLAGS variables
- add $(BASH) to run bash scripts
- change *CFLAGS_<basetarget>.o to take the relative path to $(obj)
instead of the basename
- stop suppressing Clang's -Wunused-function warnings when W=1
- fix linux/export.h to avoid genksyms calculating CRC of trimmed
exported symbols
- misc cleanups
* tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits)
genksyms: convert to SPDX License Identifier for lex.l and parse.y
modpost: use __section in the output to *.mod.c
modpost: use MODULE_INFO() for __module_depends
export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols
export.h: remove defined(__KERNEL__), which is no longer needed
kbuild: allow Clang to find unused static inline functions for W=1 build
kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN
kbuild: refactor scripts/Makefile.extrawarn
merge_config.sh: ignore unwanted grep errors
kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj)
modpost: add NOFAIL to strndup
modpost: add guid_t type definition
kbuild: add $(BASH) to run scripts with bash-extension
kbuild: remove ARCH_{CPP,A,C}FLAGS
kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
kbuild: Do not enable -Wimplicit-fallthrough for clang for now
kbuild: clean up subdir-ymn calculation in Makefile.clean
kbuild: remove unneeded '+' marker from cmd_clean
kbuild: remove clean-dirs syntax
kbuild: check clean srctree even earlier
...
- A bunch of DT binding conversions to DT schema format
- Clean-ups of the Arm idle-states binding
- Support a default number of cells in of_for_each_phandle() when the
cells name is missing
- Expose dtbs_check and dt_binding_check in the make help
- Convert writting-schema.md to ReST
- HiSilicon reset controller binding updates
- Add documentation for MT8516 RNG
-----BEGIN PGP SIGNATURE-----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=ZO6c
-----END PGP SIGNATURE-----
Merge tag 'devicetree-for-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull Devicetree updates from Rob Herring:
- a bunch of DT binding conversions to DT schema format
- clean-ups of the Arm idle-states binding
- support a default number of cells in of_for_each_phandle() when the
cells name is missing
- expose dtbs_check and dt_binding_check in the make help
- convert writting-schema.md to ReST
- HiSilicon reset controller binding updates
- add documentation for MT8516 RNG
* tag 'devicetree-for-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (46 commits)
of: restore old handling of cells_name=NULL in of_*_phandle_with_args()
bus: qcom: fix spelling mistake "ambigous" -> "ambiguous"
of: Let of_for_each_phandle fallback to non-negative cell_count
iommu: pass cell_count = -1 to of_for_each_phandle with cells_name
dt-bindings: arm: Convert Realtek board/soc bindings to json-schema
dt-bindings: arm: Convert Actions Semi bindings to jsonschema
dt-bindings: Correct spelling in example schema
dt-bindings: cpu: Add a support cpu type for cortex-a55
dt-bindings: gpu: mali-midgard: Add samsung exynos5250 compatible
dt-bindings: arm: idle-states: Move exit-latency-us explanation
dt-bindings: arm: idle-states: Add punctuation to improve readability
dt-bindings: arm: idle-states: Correct "constraint guarantees"
dt-bindings: arm: idle-states: Correct references to wake-up delay
dt-bindings: arm: idle-states: Use "e.g." and "i.e." consistently
pinctrl-mcp23s08: Fix property-name in dt-example
dt-bindings: Clarify interrupts-extended usage
dt-bindings: Convert Arm Mali Utgard GPU to DT schema
dt-bindings: Convert Arm Mali Bifrost GPU to DT schema
dt-bindings: Convert Arm Mali Midgard GPU to DT schema
dt-bindings: irq: Convert Allwinner NMI Controller to a schema
...
- 52-bit virtual addressing in the kernel
- New ABI to allow tagged user pointers to be dereferenced by syscalls
- Early RNG seeding by the bootloader
- Improve robustness of SMP boot
- Fix TLB invalidation in light of recent architectural clarifications
- Support for i.MX8 DDR PMU
- Remove direct LSE instruction patching in favour of static keys
- Function error injection using kprobes
- Support for the PPTT "thread" flag introduced by ACPI 6.3
- Move PSCI idle code into proper cpuidle driver
- Relaxation of implicit I/O memory barriers
- Build with RELR relocations when toolchain supports them
- Numerous cleanups and non-critical fixes
-----BEGIN PGP SIGNATURE-----
iQFEBAABCgAuFiEEPxTL6PPUbjXGY88ct6xw3ITBYzQFAl1yYREQHHdpbGxAa2Vy
bmVsLm9yZwAKCRC3rHDchMFjNAM3CAChqDFQkryXoHwdeEcaukMRVNxtxOi4pM4g
5xqkb7PoqRJssIblsuhaXjrSD97yWCgaqCmFe6rKoes++lP4bFcTe22KXPPyPBED
A+tK4nTuKKcZfVbEanUjI+ihXaHJmKZ/kwAxWsEBYZ4WCOe3voCiJVNO2fHxqg1M
8TskZ2BoayTbWMXih0eJg2MCy/xApBq4b3nZG4bKI7Z9UpXiKN1NYtDh98ZEBK4V
d/oNoHsJ2ZvIQsztoBJMsvr09DTCazCijWZiECadm6l41WEPFizngrACiSJLLtYo
0qu4qxgg9zgFlvBCRQmIYSggTuv35RgXSfcOwChmW5DUjHG+f9GK
=Ru4B
-----END PGP SIGNATURE-----
Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
"Although there isn't tonnes of code in terms of line count, there are
a fair few headline features which I've noted both in the tag and also
in the merge commits when I pulled everything together.
The part I'm most pleased with is that we had 35 contributors this
time around, which feels like a big jump from the usual small group of
core arm64 arch developers. Hopefully they all enjoyed it so much that
they'll continue to contribute, but we'll see.
It's probably worth highlighting that we've pulled in a branch from
the risc-v folks which moves our CPU topology code out to where it can
be shared with others.
Summary:
- 52-bit virtual addressing in the kernel
- New ABI to allow tagged user pointers to be dereferenced by
syscalls
- Early RNG seeding by the bootloader
- Improve robustness of SMP boot
- Fix TLB invalidation in light of recent architectural
clarifications
- Support for i.MX8 DDR PMU
- Remove direct LSE instruction patching in favour of static keys
- Function error injection using kprobes
- Support for the PPTT "thread" flag introduced by ACPI 6.3
- Move PSCI idle code into proper cpuidle driver
- Relaxation of implicit I/O memory barriers
- Build with RELR relocations when toolchain supports them
- Numerous cleanups and non-critical fixes"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (114 commits)
arm64: remove __iounmap
arm64: atomics: Use K constraint when toolchain appears to support it
arm64: atomics: Undefine internal macros after use
arm64: lse: Make ARM64_LSE_ATOMICS depend on JUMP_LABEL
arm64: asm: Kill 'asm/atomic_arch.h'
arm64: lse: Remove unused 'alt_lse' assembly macro
arm64: atomics: Remove atomic_ll_sc compilation unit
arm64: avoid using hard-coded registers for LSE atomics
arm64: atomics: avoid out-of-line ll/sc atomics
arm64: Use correct ll/sc atomic constraints
jump_label: Don't warn on __exit jump entries
docs/perf: Add documentation for the i.MX8 DDR PMU
perf/imx_ddr: Add support for AXI ID filtering
arm64: kpti: ensure patched kernel text is fetched from PoU
arm64: fix fixmap copy for 16K pages and 48-bit VA
perf/smmuv3: Validate groups for global filtering
perf/smmuv3: Validate group size
arm64: Relax Documentation/arm64/tagged-pointers.rst
arm64: kvm: Replace hardcoded '1' with SYS_PAR_EL1_F
arm64: mm: Ignore spurious translation faults taken from the kernel
...
A script that uses the '<module>.ns_deps' files generated by modpost to
automatically add the required symbol namespace dependencies to each
module.
Usage:
1) Move some symbols to a namespace with EXPORT_SYMBOL_NS() or define
DEFAULT_SYMBOL_NAMESPACE
2) Run 'make' (or 'make modules') and get warnings about modules not
importing that namespace.
3) Run 'make nsdeps' to automatically add required import statements
to said modules.
This makes it easer for subsystem maintainers to introduce and maintain
symbol namespaces into their codebase.
Co-developed-by: Martijn Coenen <maco@android.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
This patch adds an option to modpost to generate a <module>.ns_deps file
per module, containing the namespace dependencies for that module.
E.g. if the linked module my-module.ko would depend on the symbol
myfunc.MY_NS in the namespace MY_NS, the my-module.ns_deps file created
by modpost would contain the entry MY_NS to express the namespace
dependency of my-module imposed by using the symbol myfunc.
These files can subsequently be used by static analysis tools (like
coccinelle scripts) to address issues with missing namespace imports. A
later patch of this series will introduce such a script 'nsdeps' and a
corresponding make target to automatically add missing
MODULE_IMPORT_NS() definitions to the module's sources. For that it uses
the information provided in the generated .ns_deps files.
Co-developed-by: Martijn Coenen <maco@android.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
KBUILD_ENABLE_EXTRA_GCC_CHECKS started as a switch to add extra warning
options for GCC, but now it is a historical misnomer since we use it
also for Clang, DTC, and even kernel-doc.
Rename it to more sensible, shorter KBUILD_EXTRA_WARN.
For the backward compatibility, KBUILD_ENABLE_EXTRA_GCC_CHECKS is still
supported (but not advertised in the documentation).
I also fixed up 'make help', and updated the documentation.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
CONFIG_SHELL falls back to sh when bash is not installed on the system,
but nobody is testing such a case since bash is usually installed.
So, shell scripts invoked by CONFIG_SHELL are only tested with bash.
It makes it difficult to test whether the hashbang #!/bin/sh is real.
For example, #!/bin/sh in arch/powerpc/kernel/prom_init_check.sh is
false. (I fixed it up)
Besides, some shell scripts invoked by CONFIG_SHELL use bash-extension
and #!/bin/bash is specified as the hashbang, while CONFIG_SHELL may
not always be set to bash.
Probably, the right thing to do is to introduce BASH, which is bash by
default, and always set CONFIG_SHELL to sh. Replace $(CONFIG_SHELL)
with $(BASH) for bash scripts.
If somebody tries to add bash-extension to a #!/bin/sh script, it will
be caught in testing because /bin/sh is a symlink to dash on some major
distributions.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
These flags were added by commit 61754c1875 ("kbuild: Allow arch
Makefiles to override {cpp,ld,c}flags") to allow ARC to override -O2.
We did not see any other usage after all. Now that ARC switched to
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3, there is no more user of
these variables.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
arch/arc/Makefile overrides -O2 with -O3. This is the only user of
ARCH_CFLAGS. There is no user of ARCH_CPPFLAGS or ARCH_AFLAGS.
My plan is to remove ARCH_{CPP,A,C}FLAGS after refactoring the ARC
Makefile.
Currently, ARC has no way to enable -Wmaybe-uninitialized because both
-O3 and -Os disable it. Enabling it will be useful for compile-testing.
This commit allows allmodconfig (, which defaults to -O2) to enable it.
Add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y to all the defconfig files
in arch/arc/configs/ in order to keep the current config settings.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
This functionally reverts commit bfd77145f3 ("Makefile: Convert
-Wimplicit-fallthrough=3 to just -Wimplicit-fallthrough for clang").
clang enabled support for -Wimplicit-fallthrough in C in r369414 [1],
which causes a lot of warnings when building the kernel for two reasons:
1. Clang does not support the /* fall through */ comments. There seems
to be a general consensus in the LLVM community that this is not
something they want to support. Joe Perches wrote a script to convert
all of the comments to a "fallthrough" keyword that will be added to
compiler_attributes.h [2] [3], which catches the vast majority of the
comments. There doesn't appear to be any consensus in the kernel
community when to do this conversion.
2. Clang and GCC disagree about falling through to final case statements
with no content or cases that simply break:
https://godbolt.org/z/c8csDu
This difference contributes at least 50 warnings in an allyesconfig
build for x86, not considering other architectures. This difference
will need to be discussed to see which compiler is right [4] [5].
[1]: 1e0affb6e5
[2]: https://lore.kernel.org/lkml/61ddbb86d5e68a15e24ccb06d9b399bbf5ce2da7.camel@perches.com/
[3]: https://lore.kernel.org/lkml/1d2830aadbe9d8151728a7df5b88528fc72a0095.1564549413.git.joe@perches.com/
[4]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91432
[5]: https://github.com/ClangBuiltLinux/linux/issues/636
Given these two problems need discussion and coordination, do not enable
-Wimplicit-fallthrough with clang right now. Add a comment to explain
what is going on as well. This commit should be reverted once these two
issues are fully flushed out and resolved.
Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Move the outputmakefile target to the leftmost in the prerequisite list
so that this is checked first. GNU Make processes the prerequisites
left to right.
GNU Make will keep to stick to this behavior, and it seems even
POSIX standard, according to this:
https://lists.gnu.org/archive/html/bug-make/2019-08/msg00030.html
The POSIX standard of make is available here:
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html
Of course, when the parallel option -j given, other targets will be run
simultaneously but it is nice to show the error as early as possible.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
