[PATCH] kbuild: mark prepare0 as PHONY to fix external module build

[Michael Ellerman]

Masahiro Yamada <yamada.masahiro at socionext.com> writes:
> On Tue, Jan 15, 2019 at 5:07 PM Masahiro Yamada
> <yamada.masahiro at socionext.com> wrote:
>>
>> Commit c3ff2a5193fa ("powerpc/32: add stack protector support")
>> caused kernel panic on PowerPC if an external module is used with
>> CONFIG_STACKPROTECTOR because the 'prepare' target was not executed
>> for the external module build.
>>
>> Commit e07db28eea38 ("kbuild: fix single target build for external
>> module") turned it into a build error because the 'prepare' target is
>> now executed but the 'prepare0' target is missing for the external
>> module build.
>>
>> External module on arm/arm64 with CONFIG_STACKPROTECTOR_PER_TASK is
>> also broken in the same way.
>>
>> Move 'PHONY += prepare0' to the common place. Make is fine with missing
>> rule for phony targets.
>>
>> I minimize the change so it can be easily backported to 4.20.x
>>
>> To fix v4.20 for external modules of PowerPC, please backport
>> e07db28eea38 ("kbuild: fix single target build for external module"),
>> and then this commit.
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=201891
>> Fixes: e07db28eea38 ("kbuild: fix single target build for external module")
>> Fixes: c3ff2a5193fa ("powerpc/32: add stack protector support")
>> Fixes: 189af4657186 ("ARM: smp: add support for per-task stack canaries")
>> Fixes: 0a1213fa7432 ("arm64: enable per-task stack canaries")
>> Cc: linux-stable <stable at vger.kernel.org> # v4.20
>> Reported-by: Samuel Holland <samuel at sholland.org>
>> Reported-by: Alexey Kardashevskiy <aik at ozlabs.ru>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
>> ---
>
> Applied to linux-kbuild/fixes.

Thanks.

cheers