linux-stable.git/scripts, branch v5.15.78 Linux kernel stable tree kbuild: rpm-pkg: fix breakage when V=1 is used 2022-10-26T10:35:27+00:00 Janis Schoetterl-Glausch scgl@linux.ibm.com 2022-09-16T12:41:12+00:00 c963ce2fa05df45cf9b4c0854ed7abb2911132f7 [ Upstream commit 2e07005f4813a9ff6e895787e0c2d1fea859b033 ] Doing make V=1 binrpm-pkg results in: Executing(%install): /bin/sh -e /var/tmp/rpm-tmp.EgV6qJ + umask 022 + cd . + /bin/rm -rf /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x + /bin/mkdir -p /home/scgl/rpmbuild/BUILDROOT + /bin/mkdir /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x + mkdir -p /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x/boot + make -f ./Makefile image_name + cp test -e include/generated/autoconf.h -a -e include/config/auto.conf || ( \ echo >&2; \ echo >&2 " ERROR: Kernel configuration is invalid."; \ echo >&2 " include/generated/autoconf.h or include/config/auto.conf are missing.";\ echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \ echo >&2 ; \ /bin/false) arch/s390/boot/bzImage /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x/boot/vmlinuz-6.0.0-rc5+ cp: invalid option -- 'e' Try 'cp --help' for more information. error: Bad exit status from /var/tmp/rpm-tmp.EgV6qJ (%install) Because the make call to get the image name is verbose and prints additional information. Fixes: 993bdde94547 ("kbuild: add image_name to no-sync-config-targets") Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2e07005f4813a9ff6e895787e0c2d1fea859b033 ]

Doing make V=1 binrpm-pkg results in:

 Executing(%install): /bin/sh -e /var/tmp/rpm-tmp.EgV6qJ
 + umask 022
 + cd .
 + /bin/rm -rf /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x
 + /bin/mkdir -p /home/scgl/rpmbuild/BUILDROOT
 + /bin/mkdir /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x
 + mkdir -p /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x/boot
 + make -f ./Makefile image_name
 + cp test -e include/generated/autoconf.h -a -e include/config/auto.conf || ( \ echo >&2; \ echo >&2 " ERROR: Kernel configuration is invalid."; \ echo >&2 " include/generated/autoconf.h or include/config/auto.conf are missing.";\ echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \ echo >&2 ; \ /bin/false) arch/s390/boot/bzImage /home/scgl/rpmbuild/BUILDROOT/kernel-6.0.0_rc5+-1.s390x/boot/vmlinuz-6.0.0-rc5+
 cp: invalid option -- 'e'
 Try 'cp --help' for more information.
 error: Bad exit status from /var/tmp/rpm-tmp.EgV6qJ (%install)

Because the make call to get the image name is verbose and prints
additional information.

Fixes: 993bdde94547 ("kbuild: add image_name to no-sync-config-targets")
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
kbuild: remove the target in signal traps when interrupted 2022-10-26T10:35:27+00:00 Masahiro Yamada masahiroy@kernel.org 2022-08-07T00:48:09+00:00 059ce6b68b76ca04331608e07adb18ebd16de6f2 [ Upstream commit a7f3257da8a86b96fb9bf1bba40ae0bbd7f1885a ] When receiving some signal, GNU Make automatically deletes the target if it has already been changed by the interrupted recipe. If the target is possibly incomplete due to interruption, it must be deleted so that it will be remade from scratch on the next run of make. Otherwise, the target would remain corrupted permanently because its timestamp had already been updated. Thanks to this behavior of Make, you can stop the build any time by pressing Ctrl-C, and just run 'make' to resume it. Kbuild also relies on this feature, but it is equivalently important for any build systems that make decisions based on timestamps (if you want to support Ctrl-C reliably). However, this does not always work as claimed; Make immediately dies with Ctrl-C if its stderr goes into a pipe. [Test Makefile] foo: echo hello > $@ sleep 3 echo world >> $@ [Test Result] $ make # hit Ctrl-C echo hello > foo sleep 3 ^Cmake: *** Deleting file 'foo' make: *** [Makefile:3: foo] Interrupt $ make 2>&1 | cat # hit Ctrl-C echo hello > foo sleep 3 ^C$ # 'foo' is often left-over The reason is because SIGINT is sent to the entire process group. In this example, SIGINT kills 'cat', and 'make' writes the message to the closed pipe, then dies with SIGPIPE before cleaning the target. A typical bad scenario (as reported by [1], [2]) is to save build log by using the 'tee' command: $ make 2>&1 | tee log This can be problematic for any build systems based on Make, so I hope it will be fixed in GNU Make. The maintainer of GNU Make stated this is a long-standing issue and difficult to fix [3]. It has not been fixed yet as of writing. So, we cannot rely on Make cleaning the target. We can do it by ourselves, in signal traps. As far as I understand, Make takes care of SIGHUP, SIGINT, SIGQUIT, and SITERM for the target removal. I added the traps for them, and also for SIGPIPE just in case cmd_* rule prints something to stdout or stderr (but I did not observe an actual case where SIGPIPE was triggered). [Note 1] The trap handler might be worth explaining. rm -f $@; trap - $(sig); kill -s $(sig) $$ This lets the shell kill itself by the signal it caught, so the parent process can tell the child has exited on the signal. Generally, this is a proper manner for handling signals, in case the calling program (like Bash) may monitor WIFSIGNALED() and WTERMSIG() for WCE although this may not be a big deal here because GNU Make handles SIGHUP, SIGINT, SIGQUIT in WUE and SIGTERM in IUE. IUE - Immediate Unconditional Exit WUE - Wait and Unconditional Exit WCE - Wait and Cooperative Exit For details, see "Proper handling of SIGINT/SIGQUIT" [4]. [Note 2] Reverting 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files") would directly address [1], but it only saves if_changed_dep. As reported in [2], all commands that use redirection can potentially leave an empty (i.e. broken) target. [Note 3] Another (even safer) approach might be to always write to a temporary file, and rename it to $@ at the end of the recipe. <command> > $(tmp-target) mv $(tmp-target) $@ It would require a lot of Makefile changes, and result in ugly code, so I did not take it. [Note 4] A little more thoughts about a pattern rule with multiple targets (or a grouped target). %.x %.y: %.z <recipe> When interrupted, GNU Make deletes both %.x and %.y, while this solution only deletes $@. Probably, this is not a big deal. The next run of make will execute the rule again to create $@ along with the other files. [1]: https://lore.kernel.org/all/YLeot94yAaM4xbMY@gmail.com/ [2]: https://lore.kernel.org/all/20220510221333.2770571-1-robh@kernel.org/ [3]: https://lists.gnu.org/archive/html/help-make/2021-06/msg00001.html [4]: https://www.cons.org/cracauer/sigint.html Fixes: 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files") Reported-by: Ingo Molnar <mingo@kernel.org> Reported-by: Rob Herring <robh@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit a7f3257da8a86b96fb9bf1bba40ae0bbd7f1885a ]

When receiving some signal, GNU Make automatically deletes the target if
it has already been changed by the interrupted recipe.

If the target is possibly incomplete due to interruption, it must be
deleted so that it will be remade from scratch on the next run of make.
Otherwise, the target would remain corrupted permanently because its
timestamp had already been updated.

Thanks to this behavior of Make, you can stop the build any time by
pressing Ctrl-C, and just run 'make' to resume it.

Kbuild also relies on this feature, but it is equivalently important
for any build systems that make decisions based on timestamps (if you
want to support Ctrl-C reliably).

However, this does not always work as claimed; Make immediately dies
with Ctrl-C if its stderr goes into a pipe.

  [Test Makefile]

    foo:
            echo hello > $@
            sleep 3
            echo world >> $@

  [Test Result]

    $ make                         # hit Ctrl-C
    echo hello > foo
    sleep 3
    ^Cmake: *** Deleting file 'foo'
    make: *** [Makefile:3: foo] Interrupt

    $ make 2>&1 | cat              # hit Ctrl-C
    echo hello > foo
    sleep 3
    ^C$                            # 'foo' is often left-over

The reason is because SIGINT is sent to the entire process group.
In this example, SIGINT kills 'cat', and 'make' writes the message to
the closed pipe, then dies with SIGPIPE before cleaning the target.

A typical bad scenario (as reported by [1], [2]) is to save build log
by using the 'tee' command:

    $ make 2>&1 | tee log

This can be problematic for any build systems based on Make, so I hope
it will be fixed in GNU Make. The maintainer of GNU Make stated this is
a long-standing issue and difficult to fix [3]. It has not been fixed
yet as of writing.

So, we cannot rely on Make cleaning the target. We can do it by
ourselves, in signal traps.

As far as I understand, Make takes care of SIGHUP, SIGINT, SIGQUIT, and
SITERM for the target removal. I added the traps for them, and also for
SIGPIPE just in case cmd_* rule prints something to stdout or stderr
(but I did not observe an actual case where SIGPIPE was triggered).

[Note 1]

The trap handler might be worth explaining.

    rm -f $@; trap - $(sig); kill -s $(sig) $$

This lets the shell kill itself by the signal it caught, so the parent
process can tell the child has exited on the signal. Generally, this is
a proper manner for handling signals, in case the calling program (like
Bash) may monitor WIFSIGNALED() and WTERMSIG() for WCE although this may
not be a big deal here because GNU Make handles SIGHUP, SIGINT, SIGQUIT
in WUE and SIGTERM in IUE.

  IUE - Immediate Unconditional Exit
  WUE - Wait and Unconditional Exit
  WCE - Wait and Cooperative Exit

For details, see "Proper handling of SIGINT/SIGQUIT" [4].

[Note 2]

Reverting 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd
files") would directly address [1], but it only saves if_changed_dep.
As reported in [2], all commands that use redirection can potentially
leave an empty (i.e. broken) target.

[Note 3]

Another (even safer) approach might be to always write to a temporary
file, and rename it to $@ at the end of the recipe.

   <command>  > $(tmp-target)
   mv $(tmp-target) $@

It would require a lot of Makefile changes, and result in ugly code,
so I did not take it.

[Note 4]

A little more thoughts about a pattern rule with multiple targets (or
a grouped target).

    %.x %.y: %.z
            <recipe>

When interrupted, GNU Make deletes both %.x and %.y, while this solution
only deletes $@. Probably, this is not a big deal. The next run of make
will execute the rule again to create $@ along with the other files.

[1]: https://lore.kernel.org/all/YLeot94yAaM4xbMY@gmail.com/
[2]: https://lore.kernel.org/all/20220510221333.2770571-1-robh@kernel.org/
[3]: https://lists.gnu.org/archive/html/help-make/2021-06/msg00001.html
[4]: https://www.cons.org/cracauer/sigint.html

Fixes: 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files")
Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: Rob Herring <robh@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
selinux: use "grep -E" instead of "egrep" 2022-10-26T10:34:35+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2022-09-20T17:12:52+00:00 b7af9b8be89171f5bd842d8813eddeb846433ff3 commit c969bb8dbaf2f3628927eae73e7c579a74cf1b6e upstream. The latest version of grep claims that egrep is now obsolete so the build now contains warnings that look like: egrep: warning: egrep is obsolescent; using grep -E fix this by using "grep -E" instead. Cc: Paul Moore <paul@paul-moore.com> Cc: Stephen Smalley <stephen.smalley.work@gmail.com> Cc: Eric Paris <eparis@parisplace.org> Cc: selinux@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [PM: tweak to remove vdso reference, cleanup subj line] Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c969bb8dbaf2f3628927eae73e7c579a74cf1b6e upstream.

The latest version of grep claims that egrep is now obsolete so the build
now contains warnings that look like:
	egrep: warning: egrep is obsolescent; using grep -E
fix this by using "grep -E" instead.

Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: selinux@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[PM: tweak to remove vdso reference, cleanup subj line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Makefile.extrawarn: Move -Wcast-function-type-strict to W=1 2022-10-12T07:53:26+00:00 Sami Tolvanen samitolvanen@google.com 2022-09-30T20:33:10+00:00 cf26ddb96b4f7163ebe1bcdb83e104aa5e497c69 commit 2120635108b35ecad9c59c8b44f6cbdf4f98214e upstream. We enable -Wcast-function-type globally in the kernel to warn about mismatching types in function pointer casts. Compilers currently warn only about ABI incompability with this flag, but Clang 16 will enable a stricter version of the check by default that checks for an exact type match. This will be very noisy in the kernel, so disable -Wcast-function-type-strict without W=1 until the new warnings have been addressed. Cc: stable@vger.kernel.org Link: https://reviews.llvm.org/D134831 Link: https://github.com/ClangBuiltLinux/linux/issues/1724 Suggested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220930203310.4010564-1-samitolvanen@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2120635108b35ecad9c59c8b44f6cbdf4f98214e upstream.

We enable -Wcast-function-type globally in the kernel to warn about
mismatching types in function pointer casts. Compilers currently
warn only about ABI incompability with this flag, but Clang 16 will
enable a stricter version of the check by default that checks for an
exact type match. This will be very noisy in the kernel, so disable
-Wcast-function-type-strict without W=1 until the new warnings have
been addressed.

Cc: stable@vger.kernel.org
Link: https://reviews.llvm.org/D134831
Link: https://github.com/ClangBuiltLinux/linux/issues/1724
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220930203310.4010564-1-samitolvanen@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mksysmap: Fix the mismatch of 'L0' symbols in System.map 2022-09-23T12:15:51+00:00 Youling Tang tangyouling@loongson.cn 2022-09-01T11:10:59+00:00 9af7af862cb8e2557c23589446a5356e37c9d633 [ Upstream commit c17a2538704f926ee4d167ba625e09b1040d8439 ] When System.map was generated, the kernel used mksysmap to filter the kernel symbols, we need to filter "L0" symbols in LoongArch architecture. $ cat System.map | grep L0 9000000000221540 t L0 The L0 symbol exists in System.map, but not in .tmp_System.map. When "cmp -s System.map .tmp_System.map" will show "Inconsistent kallsyms data" error message in link-vmlinux.sh script. Signed-off-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit c17a2538704f926ee4d167ba625e09b1040d8439 ]

When System.map was generated, the kernel used mksysmap to filter the
kernel symbols, we need to filter "L0" symbols in LoongArch architecture.

$ cat System.map | grep L0
9000000000221540 t L0

The L0 symbol exists in System.map, but not in .tmp_System.map. When
"cmp -s System.map .tmp_System.map" will show "Inconsistent kallsyms
data" error message in link-vmlinux.sh script.

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
kbuild: fix up permissions on scripts/pahole-flags.sh 2022-09-08T10:30:36+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2022-09-08T10:30:36+00:00 096e34b05a439f0e607529d9404be3c3f59d2064 Commit b775fbf532dc ("kbuild: Add skip_encoding_btf_enum64 option to pahole") created the file scripts/pahole-flags.sh, but due to a mismatch between patch and quilt and git, the execute permissions did not get set properly. Fix that up. Reported-by: Florian Fainelli <f.fainelli@gmail.com> Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Fixes: b775fbf532dc ("kbuild: Add skip_encoding_btf_enum64 option to pahole") Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Commit b775fbf532dc ("kbuild: Add skip_encoding_btf_enum64 option to
pahole") created the file scripts/pahole-flags.sh, but due to a mismatch
between patch and quilt and git, the execute permissions did not get set
properly.  Fix that up.

Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Fixes: b775fbf532dc ("kbuild: Add skip_encoding_btf_enum64 option to pahole")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kbuild: Add skip_encoding_btf_enum64 option to pahole 2022-09-08T10:28:08+00:00 Martin Rodriguez Reboredo yakoyoku@gmail.com 2022-09-04T13:19:01+00:00 b775fbf532dc01ae53a6fc56168fd30cb4b0c658 New pahole (version 1.24) generates by default new BTF_KIND_ENUM64 BTF tag, which is not supported by stable kernel. As a result the kernel with CONFIG_DEBUG_INFO_BTF option will fail to compile with following error: BTFIDS vmlinux FAILED: load BTF from vmlinux: Invalid argument New pahole provides --skip_encoding_btf_enum64 option to skip BTF_KIND_ENUM64 generation and produce BTF supported by stable kernel. Adding this option to scripts/pahole-flags.sh. This change does not have equivalent commit in linus tree, because linus tree has support for BTF_KIND_ENUM64 tag, so it does not need to be disabled. Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
New pahole (version 1.24) generates by default new BTF_KIND_ENUM64 BTF tag,
which is not supported by stable kernel.

As a result the kernel with CONFIG_DEBUG_INFO_BTF option will fail to
compile with following error:

  BTFIDS  vmlinux
FAILED: load BTF from vmlinux: Invalid argument

New pahole provides --skip_encoding_btf_enum64 option to skip BTF_KIND_ENUM64
generation and produce BTF supported by stable kernel.

Adding this option to scripts/pahole-flags.sh.

This change does not have equivalent commit in linus tree, because linus tree
has support for BTF_KIND_ENUM64 tag, so it does not need to be disabled.

Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kbuild: Unify options for BTF generation for vmlinux and modules 2022-09-08T10:28:08+00:00 Jiri Olsa jolsa@redhat.com 2022-09-04T13:19:00+00:00 0baced0e0938f2895ceba54038eaf15ed91032e7 commit e27f05147bff21408c1b8410ad8e90cd286e7952 upstream. Using new PAHOLE_FLAGS variable to pass extra arguments to pahole for both vmlinux and modules BTF data generation. Adding new scripts/pahole-flags.sh script that detect and prints pahole options. [ fixed issues found by kernel test robot ] Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211029125729.70002-1-jolsa@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e27f05147bff21408c1b8410ad8e90cd286e7952 upstream.

Using new PAHOLE_FLAGS variable to pass extra arguments to
pahole for both vmlinux and modules BTF data generation.

Adding new scripts/pahole-flags.sh script that detect and
prints pahole options.

[ fixed issues found by kernel test robot ]

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211029125729.70002-1-jolsa@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kbuild: Fix include path in scripts/Makefile.modpost 2022-09-05T08:30:06+00:00 Jing Leng jleng@ambarella.com 2022-05-17T10:51:28+00:00 2e0ffef173081f0e914a7e39caafae16120db111 commit 23a0cb8e3225122496bfa79172005c587c2d64bf upstream. When building an external module, if users don't need to separate the compilation output and source code, they run the following command: "make -C $(LINUX_SRC_DIR) M=$(PWD)". At this point, "$(KBUILD_EXTMOD)" and "$(src)" are the same. If they need to separate them, they run "make -C $(KERNEL_SRC_DIR) O=$(KERNEL_OUT_DIR) M=$(OUT_DIR) src=$(PWD)". Before running the command, they need to copy "Kbuild" or "Makefile" to "$(OUT_DIR)" to prevent compilation failure. So the kernel should change the included path to avoid the copy operation. Signed-off-by: Jing Leng <jleng@ambarella.com> [masahiro: I do not think "M=$(OUT_DIR) src=$(PWD)" is the official way, but this patch is a nice clean up anyway.] Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Nicolas Schier <n.schier@avm.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 23a0cb8e3225122496bfa79172005c587c2d64bf upstream.

When building an external module, if users don't need to separate the
compilation output and source code, they run the following command:
"make -C $(LINUX_SRC_DIR) M=$(PWD)". At this point, "$(KBUILD_EXTMOD)"
and "$(src)" are the same.

If they need to separate them, they run "make -C $(KERNEL_SRC_DIR)
O=$(KERNEL_OUT_DIR) M=$(OUT_DIR) src=$(PWD)". Before running the
command, they need to copy "Kbuild" or "Makefile" to "$(OUT_DIR)" to
prevent compilation failure.

So the kernel should change the included path to avoid the copy operation.

Signed-off-by: Jing Leng <jleng@ambarella.com>
[masahiro: I do not think "M=$(OUT_DIR) src=$(PWD)" is the official way,
but this patch is a nice clean up anyway.]
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Nicolas Schier <n.schier@avm.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
modules: Ensure natural alignment for .altinstructions and __bug_table sections 2022-08-25T09:40:41+00:00 Helge Deller deller@gmx.de 2022-07-08T09:44:54+00:00 9774b96bce7d94bacd81dd6ddf41b359b3498a68 [ Upstream commit 87c482bdfa79f378297d92af49cdf265be199df5 ] In the kernel image vmlinux.lds.S linker scripts the .altinstructions and __bug_table sections are 4- or 8-byte aligned because they hold 32- and/or 64-bit values. Most architectures use altinstructions and BUG() or WARN() in modules as well, but in the module linker script (module.lds.S) those sections are currently missing. As consequence the linker will store their content byte-aligned by default, which then can lead to unnecessary unaligned memory accesses by the CPU when those tables are processed at runtime. Usually unaligned memory accesses are unnoticed, because either the hardware (as on x86 CPUs) or in-kernel exception handlers (e.g. on parisc or sparc) emulate and fix them up at runtime. Nevertheless, such unaligned accesses introduce a performance penalty and can even crash the kernel if there is a bug in the unalignment exception handlers (which happened once to me on the parisc architecture and which is why I noticed that issue at all). This patch fixes a non-critical issue and might be backported at any time. It's trivial and shouldn't introduce any regression because it simply tells the linker to use a different (8-byte alignment) for those sections by default. Signed-off-by: Helge Deller <deller@gmx.de> Link: https://lore.kernel.org/all/Yr8%2Fgr8e8I7tVX4d@p100/ Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 87c482bdfa79f378297d92af49cdf265be199df5 ]

In the kernel image vmlinux.lds.S linker scripts the .altinstructions
and __bug_table sections are 4- or 8-byte aligned because they hold 32-
and/or 64-bit values.

Most architectures use altinstructions and BUG() or WARN() in modules as
well, but in the module linker script (module.lds.S) those sections are
currently missing. As consequence the linker will store their content
byte-aligned by default, which then can lead to unnecessary unaligned
memory accesses by the CPU when those tables are processed at runtime.

Usually unaligned memory accesses are unnoticed, because either the
hardware (as on x86 CPUs) or in-kernel exception handlers (e.g. on
parisc or sparc) emulate and fix them up at runtime. Nevertheless, such
unaligned accesses introduce a performance penalty and can even crash
the kernel if there is a bug in the unalignment exception handlers
(which happened once to me on the parisc architecture and which is why I
noticed that issue at all).

This patch fixes a non-critical issue and might be backported at any time.
It's trivial and shouldn't introduce any regression because it simply
tells the linker to use a different (8-byte alignment) for those
sections by default.

Signed-off-by: Helge Deller <deller@gmx.de>
Link: https://lore.kernel.org/all/Yr8%2Fgr8e8I7tVX4d@p100/
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>