Commit 000ec95f ("kbuild: pkg: rename scripts/package/Makefile to
scripts/Makefile.package") missed to update this comment.

Fixes: 000ec95f ("kbuild: pkg: rename scripts/package/Makefile to scripts/Makefile.package")
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

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: NMatthias Maennich <maennich@google.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NJessica 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: NShuah Khan <skhan@linuxfoundation.org>
Acked-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NShuah Khan <skhan@linuxfoundation.org>

Linux 5.3 is out. Remove the SUBDIRS support.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Commit 40df759e ("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: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Tested-by: NNick Desaulniers <ndesaulniers@google.com>

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: NMartijn Coenen <maco@android.com>
Signed-off-by: NMartijn Coenen <maco@android.com>
Acked-by: NJulia Lawall <julia.lawall@lip6.fr>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NMatthias Maennich <maennich@google.com>
Signed-off-by: NJessica 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: NMartijn Coenen <maco@android.com>
Signed-off-by: NMartijn Coenen <maco@android.com>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NMatthias Maennich <maennich@google.com>
Signed-off-by: NJessica 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: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NNathan Chancellor <natechancellor@gmail.com>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: NSedat 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: NMasahiro Yamada <yamada.masahiro@socionext.com>

These flags were added by commit 61754c18 ("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: NMasahiro 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: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NVineet Gupta <vgupta@synopsys.com>

This functionally reverts commit bfd77145 ("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]: https://github.com/llvm/llvm-project/commit/1e0affb6e564b7361b0aadb38805f26deff4ecfc
[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: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NNathan Chancellor <natechancellor@gmail.com>
Acked-by: NMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Acked-by: NNick Desaulniers <ndesaulniers@google.com>
Acked-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NMasahiro 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: NMasahiro Yamada <yamada.masahiro@socionext.com>

Now prepare3 does nothing but depends on include/config/kernel.release
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

With this commit, the error report is shown earlier, even before
running kconfig.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

If you try out-of-tree build with an unclean source tree, Kbuild
suggests to run make mrproper. The path to the source tree may be
shown with a relative path, for example, "make O=foo" emits the
following:

  .. is not clean, please run 'make mrproper'
  in the '..' directory.

This is somewhat confusing if you ran "make O=foo" in the source tree.
Using the absolute path will be clearer.

This commit changes the error message like follows:

***
*** The source tree is not clean, please run 'make mrproper'
*** in /absolute/path/to/linux
***
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Since commit 3a475b21 ("kbuild: Inform user to pass ARCH= for make
mrproper"), if you try out-of-tree build with an unclean source tree,
it suggests to run 'make ARCH=<ARCH> mrproper'.

This looks odd when you are not cross-compiling the kernel. Show the
'ARCH=<ARCH>' part only when ARCH= was given from the command line.
If ARCH is the default (native build) or came from the environment,
it should simply suggest 'make mrproper' as before.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

You already know the location of the source tree without this message.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Commit 415008af ("docs-rst: convert lsm from DocBook to ReST")
stopped using if_changed_rule. There is no more users of if_changed*
for the doc targets. Hence, fixdep is unneeded. Remove the dependency
on scripts_basic.

All the doc targets are phony. The dependency on FORCE is not needed
either.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

This line contains $(MAKE), so Make knows that it will invoke sub-make
without help of the '+' marker.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

scripts/package/Makefile does not use $(obj) or $(src) at all.
It actually generates files and directories in the top of $(objtree).
I do not see much sense in descending into scripts/package/.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

I am not a big fan of the $(objtree)/ hack for clean-files/clean-dirs.

These are created in the top of $(objtree), so let's clean them up
from the top Makefile.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

I think splitting the modpost and linking modules into separate
Makefiles will be useful especially when more complex build steps
come in. The main motivation of this commit is to integrate the
proposed klp-convert feature cleanly.

I moved the logging 'Building modules, stage 2.' to Makefile.modpost
to avoid the code duplication although I do not know whether or not
this message is needed in the first place.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Currently, the timestamp of module linker scripts are not checked.
Add them to the dependency of modules so they are correctly rebuilt.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

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: NMasahiro Yamada <yamada.masahiro@socionext.com>

Factor out the duplicated code for in-kernel and external module
cleaning.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The in-kernel build and external module build have similar code
for descending into sub-directories.

Factor out the code into the common place.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

There is no need to set 0 to variables such as config-targets,
mixed-targets, etc.

Unset instead of setting 0 in order to use 'ifdef' to test them.

I also renamed:

  config-targets  ->  config-build
  mixed-targets   ->  mixed-build
  dot-config      ->  need-config

to clarify what we are doing.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

'make clean' descends into ./Kbuild, but does not clean anything
since everything is added to no-clean-files.

There is no need to descend to ./Kbuild in the first place.
We can drop the no-clean-files assignment.

With this, there is no more user of no-clean-files. I will keep it
for a while to see whether a new user will appear.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>