On Tue, Jan 15, 2019 at 7:45 PM Alexey Kardashevskiy aik@ozlabs.ru wrote:
On 15/01/2019 18:19, Masahiro Yamada 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@vger.kernel.org # v4.20 Reported-by: Samuel Holland samuel@sholland.org Reported-by: Alexey Kardashevskiy aik@ozlabs.ru Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com
Tested-by: Alexey Kardashevskiy aik@ozlabs.ru
Thanks for fixing this! Out of curiosity - how does this work? arch/powerpc/Makefile's stack_protector_prepare still depends on prepare0 which is still defined only if KBUILD_EXTMOD=="" but somehow it does not bother ./Makefile? Thanks,
Missing phony targets are ignored.
I do not know if it is officially documented, but GNU Make works like that.
Is the following test code helpful?
[Test Makefile]
prepare: prepare0 @echo hello world
.PHONY: prepare prepare0
[Result] $ make hello world