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Date:   Fri, 12 Jul 2019 16:37:46 +0100
From:   Will Deacon <will@kernel.org>
To:     Naohiro Aota <naohiro.aota@wdc.com>
Cc:     Vincenzo Frascino <vincenzo.frascino@arm.com>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-arm-kernel@lists.infradead.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Peter Collingbourne <pcc@google.com>
Subject: Re: [PATCH v2 2/2] arm64/vdso: fix flip/flop vdso build bug
Message-ID: <20190712153746.5dwwptgrle3z25m7@willie-the-truck>
References: <20190712101556.17833-1-naohiro.aota@wdc.com>
 <20190712101556.17833-2-naohiro.aota@wdc.com>
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On Fri, Jul 12, 2019 at 07:15:56PM +0900, Naohiro Aota wrote:
> Running "make" on an already compiled kernel tree will rebuild the kernel
> even without any modifications:
> 
> $ make ARCH=arm64 CROSS_COMPILE=/usr/bin/aarch64-unknown-linux-gnu-
> arch/arm64/Makefile:58: CROSS_COMPILE_COMPAT not defined or empty, the compat vDSO will not be built
>   CALL    scripts/checksyscalls.sh
>   CALL    scripts/atomic/check-atomics.sh
>   VDSOCHK arch/arm64/kernel/vdso/vdso.so.dbg
>   VDSOSYM include/generated/vdso-offsets.h
>   CHK     include/generated/compile.h
>   CC      arch/arm64/kernel/signal.o
>   CC      arch/arm64/kernel/vdso.o
>   CC      arch/arm64/kernel/signal32.o
>   LD      arch/arm64/kernel/vdso/vdso.so.dbg
>   OBJCOPY arch/arm64/kernel/vdso/vdso.so
>   AS      arch/arm64/kernel/vdso/vdso.o
>   AR      arch/arm64/kernel/vdso/built-in.a
>   AR      arch/arm64/kernel/built-in.a
>   GEN     .version
>   CHK     include/generated/compile.h
>   UPD     include/generated/compile.h
>   CC      init/version.o
>   AR      init/built-in.a
>   LD      vmlinux.o
> 
> This is the same bug fixed in commit 92a4728608a8 ("x86/boot: Fix
> if_changed build flip/flop bug"). We cannot use two "if_changed" in one
> target. Fix this build bug by merging two commands into one function.
> 
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Fixes: 28b1a824a4f4 ("arm64: vdso: Substitute gettimeofday() with C implementation")
> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
> ---
>  arch/arm64/kernel/vdso/Makefile | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

Thanks. I've merged in Vincenzo's compat change too, so I'll send this at
-rc1 for arm64.

Will