linux-stable.git/usr, branch linux-5.4.y Linux kernel stable tree kbuild: hdrcheck: fix cross build with clang 2025-07-17T16:24:51+00:00 Arnd Bergmann arnd@arndb.de 2025-02-25T10:00:31+00:00 20fa617fe4b8cb0a8d395059bc1b738bdf2766a3 [ Upstream commit 02e9a22ceef0227175e391902d8760425fa072c6 ] The headercheck tries to call clang with a mix of compiler arguments that don't include the target architecture. When building e.g. x86 headers on arm64, this produces a warning like clang: warning: unknown platform, assuming -mfloat-abi=soft Add in the KBUILD_CPPFLAGS, which contain the target, in order to make it build properly. See also 1b71c2fb04e7 ("kbuild: userprogs: fix bitsize and target detection on clang"). Reviewed-by: Nathan Chancellor <nathan@kernel.org> Fixes: feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 02e9a22ceef0227175e391902d8760425fa072c6 ]

The headercheck tries to call clang with a mix of compiler arguments
that don't include the target architecture. When building e.g. x86
headers on arm64, this produces a warning like

   clang: warning: unknown platform, assuming -mfloat-abi=soft

Add in the KBUILD_CPPFLAGS, which contain the target, in order to make it
build properly.

See also 1b71c2fb04e7 ("kbuild: userprogs: fix bitsize and target
detection on clang").

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Fixes: feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
kbuild: add --target to correctly cross-compile UAPI headers with Clang 2025-07-17T16:24:51+00:00 Masahiro Yamada masahiroy@kernel.org 2022-03-05T12:56:05+00:00 25661f954b531df5b1de0e7ddcd91e307d885a23 [ Upstream commit 9fbed27a7a1101c926718dfa9b49aff1d04477b5 ] When you compile-test UAPI headers (CONFIG_UAPI_HEADER_TEST=y) with Clang, they are currently compiled for the host target (likely x86_64) regardless of the given ARCH=. In fact, some exported headers include libc headers. For example, include/uapi/linux/agpgart.h includes <stdlib.h> after being exported. The header search paths should match to the target we are compiling them for. Pick up the --target triple from KBUILD_CFLAGS in the same ways as commit 7f58b487e9ff ("kbuild: make Clang build userprogs for target architecture"). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Stable-dep-of: 02e9a22ceef0 ("kbuild: hdrcheck: fix cross build with clang") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 9fbed27a7a1101c926718dfa9b49aff1d04477b5 ]

When you compile-test UAPI headers (CONFIG_UAPI_HEADER_TEST=y) with
Clang, they are currently compiled for the host target (likely x86_64)
regardless of the given ARCH=.

In fact, some exported headers include libc headers. For example,
include/uapi/linux/agpgart.h includes <stdlib.h> after being exported.
The header search paths should match to the target we are compiling
them for.

Pick up the --target triple from KBUILD_CFLAGS in the same ways as
commit 7f58b487e9ff ("kbuild: make Clang build userprogs for target
architecture").

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Stable-dep-of: 02e9a22ceef0 ("kbuild: hdrcheck: fix cross build with clang")
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17T16:24:51+00:00 Masahiro Yamada masahiroy@kernel.org 2020-04-29T03:45:13+00:00 223f497f0562820e366ec13cb3be9c077bca42ba [ Upstream commit 9371f86ecb60f6f1f120e3d93fe892bbb70d04c0 ] bpfilter_umh is built for the default machine bit of the compiler, which may not match to the bit size of the kernel. This happens in the scenario below: You can use biarch GCC that defaults to 64-bit for building the 32-bit kernel. In this case, Kbuild passes -m32 to teach the compiler to produce 32-bit kernel space objects. However, it is missing when building bpfilter_umh. It is built as a 64-bit ELF, and then embedded into the 32-bit kernel. The 32-bit kernel and 64-bit umh is a bad combination. In theory, we can have 32-bit umh running on 64-bit kernel, but we do not have a good reason to support such a usecase. The best is to match the bit size between them. Pass -m32 or -m64 to the umh build command if it is found in $(KBUILD_CFLAGS). Evaluate CC_CAN_LINK against the kernel bit-size. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Stable-dep-of: 02e9a22ceef0 ("kbuild: hdrcheck: fix cross build with clang") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 9371f86ecb60f6f1f120e3d93fe892bbb70d04c0 ]

bpfilter_umh is built for the default machine bit of the compiler,
which may not match to the bit size of the kernel.

This happens in the scenario below:

You can use biarch GCC that defaults to 64-bit for building the 32-bit
kernel. In this case, Kbuild passes -m32 to teach the compiler to
produce 32-bit kernel space objects. However, it is missing when
building bpfilter_umh. It is built as a 64-bit ELF, and then embedded
into the 32-bit kernel.

The 32-bit kernel and 64-bit umh is a bad combination.

In theory, we can have 32-bit umh running on 64-bit kernel, but we do
not have a good reason to support such a usecase.

The best is to match the bit size between them.

Pass -m32 or -m64 to the umh build command if it is found in
$(KBUILD_CFLAGS). Evaluate CC_CAN_LINK against the kernel bit-size.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Stable-dep-of: 02e9a22ceef0 ("kbuild: hdrcheck: fix cross build with clang")
Signed-off-by: Sasha Levin <sashal@kernel.org>
kbuild: use -MMD instead of -MD to exclude system headers from dependency 2025-07-17T16:24:51+00:00 Masahiro Yamada masahiroy@kernel.org 2020-04-23T14:23:53+00:00 445164274701b21fc1589ff62e92b38580afa5ce [ Upstream commit 30a7729771731971839cc969d2a321e6ea7a144b ] This omits system headers from the generated header dependency. System headers are not updated unless you upgrade the compiler. Nor do they contain CONFIG options, so fixdep does not need to parse them. Having said that, the effect of this optimization will be quite small because the kernel code generally does not include system headers except <stdarg.h>. Host programs include a lot of system headers, but there are not so many in the kernel tree. At first, keeping system headers in .*.cmd files might be useful to detect the compiler update, but there is no guarantee that <stdarg.h> is included from every file. So, I implemented a more reliable way in the previous commit. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Stable-dep-of: 02e9a22ceef0 ("kbuild: hdrcheck: fix cross build with clang") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 30a7729771731971839cc969d2a321e6ea7a144b ]

This omits system headers from the generated header dependency.

System headers are not updated unless you upgrade the compiler. Nor do
they contain CONFIG options, so fixdep does not need to parse them.

Having said that, the effect of this optimization will be quite small
because the kernel code generally does not include system headers
except <stdarg.h>. Host programs include a lot of system headers,
but there are not so many in the kernel tree.

At first, keeping system headers in .*.cmd files might be useful to
detect the compiler update, but there is no guarantee that <stdarg.h>
is included from every file. So, I implemented a more reliable way in
the previous commit.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Stable-dep-of: 02e9a22ceef0 ("kbuild: hdrcheck: fix cross build with clang")
Signed-off-by: Sasha Levin <sashal@kernel.org>
initramfs: restore default compression behavior 2020-04-08T07:08:38+00:00 Eugeniy Paltsev Eugeniy.Paltsev@synopsys.com 2020-03-16T11:25:19+00:00 d2faee42f9e7dbe147de6d049e33ee9de51b404d [ Upstream commit 785d74ec3bbf26ac7f6e92e6e96a259aec0f107a ] Even though INITRAMFS_SOURCE kconfig option isn't set in most of defconfigs it is used (set) extensively by various build systems. Commit f26661e12765 ("initramfs: make initramfs compression choice non-optional") has changed default compression mode. Previously we compress initramfs using available compression algorithm. Now we don't use any compression at all by default. It significantly increases the image size in case of build system chooses embedded initramfs. Initially I faced with this issue while using buildroot. As of today it's not possible to set preferred compression mode in target defconfig as this option depends on INITRAMFS_SOURCE being set. Modification of all build systems either doesn't look like good option. Let's instead rewrite initramfs compression mode choices list the way that "INITRAMFS_COMPRESSION_NONE" will be the last option in the list. In that case it will be chosen only if all other options (which implements any compression) are not available. Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 785d74ec3bbf26ac7f6e92e6e96a259aec0f107a ]

Even though INITRAMFS_SOURCE kconfig option isn't set in most of
defconfigs it is used (set) extensively by various build systems.
Commit f26661e12765 ("initramfs: make initramfs compression choice
non-optional") has changed default compression mode. Previously we
compress initramfs using available compression algorithm. Now
we don't use any compression at all by default.
It significantly increases the image size in case of build system
chooses embedded initramfs. Initially I faced with this issue while
using buildroot.

As of today it's not possible to set preferred compression mode
in target defconfig as this option depends on INITRAMFS_SOURCE
being set. Modification of all build systems either doesn't look
like good option.

Let's instead rewrite initramfs compression mode choices list
the way that "INITRAMFS_COMPRESSION_NONE" will be the last option
in the list. In that case it will be chosen only if all other
options (which implements any compression) are not available.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
kbuild: fix 'No such file or directory' warning when cleaning 2020-03-12T12:00:09+00:00 Masahiro Yamada masahiroy@kernel.org 2019-12-04T02:51:48+00:00 c2a5e97de44adbf4a4b61b5a4e5f3fbc28b19d86 [ Upstream commit cf6b58ab2d55f5a143c88c219c8e66ff0720fa69 ] Since commit fcbb8461fd23 ("kbuild: remove header compile test"), 'make clean' with O= option in the pristine source tree emits 'No such file or directory' warning. $ git clean -d -f -x $ make O=foo clean make[1]: Entering directory '/home/masahiro/linux/foo' find: ‘usr/include’: No such file or directory make[1]: Leaving directory '/home/masahiro/linux/foo' Fixes: fcbb8461fd23 ("kbuild: remove header compile test") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit cf6b58ab2d55f5a143c88c219c8e66ff0720fa69 ]

Since commit fcbb8461fd23 ("kbuild: remove header compile test"),
'make clean' with O= option in the pristine source tree emits
'No such file or directory' warning.

$ git clean -d -f -x
$ make O=foo clean
make[1]: Entering directory '/home/masahiro/linux/foo'
find: ‘usr/include’: No such file or directory
make[1]: Leaving directory '/home/masahiro/linux/foo'

Fixes: fcbb8461fd23 ("kbuild: remove header compile test")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
kbuild: move headers_check rule to usr/include/Makefile 2020-03-05T15:43:47+00:00 Masahiro Yamada yamada.masahiro@socionext.com 2019-11-07T07:14:41+00:00 ecd77a3261ab58bb07bc00cf3ca57f052764be5b commit 7ecaf069da52e472d393f03e79d721aabd724166 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 7ecaf069da52e472d393f03e79d721aabd724166 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kbuild: remove header compile test 2020-03-05T15:43:47+00:00 Masahiro Yamada yamada.masahiro@socionext.com 2019-11-07T07:14:40+00:00 ef134d8b493c537b81e8cbd56704efff0b402d8a commit fcbb8461fd2376ba3782b5b8bd440c929b8e4980 upstream. 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> [ added to 5.4.y due to start of build warnings from backported patches because of this feature - gregkh] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit fcbb8461fd2376ba3782b5b8bd440c929b8e4980 upstream.

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>
[ added to 5.4.y due to start of build warnings from backported patches
  because of this feature - gregkh]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-09T09:20:00+00:00 Masahiro Yamada masahiroy@kernel.org 2019-12-30T13:20:06+00:00 ebf3afa3cbd1778131af012531a0f7cc896c6621 commit cc976614f59bd8e45de8ce988a6bcb5de711d994 upstream. Prior to commit 858805b336be ("kbuild: add $(BASH) to run scripts with bash-extension"), this shell script was almost always run by bash since bash is usually installed on the system by default. Now, this script is run by sh, which might be a symlink to dash. On such distributions, the following code emits an error: local dev=`LC_ALL=C ls -l "${location}"` You can reproduce the build error, for example by setting CONFIG_INITRAMFS_SOURCE="/dev". GEN usr/initramfs_data.cpio.gz ./usr/gen_initramfs_list.sh: 131: local: 1: bad variable name make[1]: *** [usr/Makefile:61: usr/initramfs_data.cpio.gz] Error 2 This is because `LC_ALL=C ls -l "${location}"` contains spaces. Surrounding it with double-quotes fixes the error. Fixes: 858805b336be ("kbuild: add $(BASH) to run scripts with bash-extension") Reported-by: Jory A. Pratt <anarchy@gentoo.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit cc976614f59bd8e45de8ce988a6bcb5de711d994 upstream.

Prior to commit 858805b336be ("kbuild: add $(BASH) to run scripts with
bash-extension"), this shell script was almost always run by bash since
bash is usually installed on the system by default.

Now, this script is run by sh, which might be a symlink to dash. On such
distributions, the following code emits an error:

  local dev=`LC_ALL=C ls -l "${location}"`

You can reproduce the build error, for example by setting
CONFIG_INITRAMFS_SOURCE="/dev".

    GEN     usr/initramfs_data.cpio.gz
  ./usr/gen_initramfs_list.sh: 131: local: 1: bad variable name
  make[1]: *** [usr/Makefile:61: usr/initramfs_data.cpio.gz] Error 2

This is because `LC_ALL=C ls -l "${location}"` contains spaces.
Surrounding it with double-quotes fixes the error.

Fixes: 858805b336be ("kbuild: add $(BASH) to run scripts with bash-extension")
Reported-by: Jory A. Pratt <anarchy@gentoo.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kbuild: update compile-test header list for v5.4-rc2 2019-10-05T06:29:49+00:00 Masahiro Yamada yamada.masahiro@socionext.com 2019-10-03T02:36:29+00:00 d188b8c901bb4966ab035ce90af02426f062e9e1 Commit 6dc280ebeed2 ("coda: remove uapi/linux/coda_psdev.h") removed a header in question. Some more build errors were fixed. Add more headers into the test coverage. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> 
Commit 6dc280ebeed2 ("coda: remove uapi/linux/coda_psdev.h") removed
a header in question. Some more build errors were fixed. Add more
headers into the test coverage.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>