linux-kernel - Re: [RFC PATCH v4 22/37] arm64: kernel: Skip validation of kuser32.o

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Date:   Fri, 29 Apr 2022 13:05:49 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Chen Zhongjin <chenzhongjin@...wei.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arch@...r.kernel.org, jthierry@...hat.com,
        catalin.marinas@....com, will@...nel.org, masahiroy@...nel.org,
        jpoimboe@...hat.com, ycote@...hat.com, herbert@...dor.apana.org.au,
        mark.rutland@....com, davem@...emloft.net, ardb@...nel.org,
        maz@...nel.org, tglx@...utronix.de, luc.vanoostenryck@...il.com
Subject: Re: [RFC PATCH v4 22/37] arm64: kernel: Skip validation of kuser32.o

On Fri, Apr 29, 2022 at 05:43:40PM +0800, Chen Zhongjin wrote:
> From: Raphael Gault <raphael.gault@....com>
> 
> kuser32 being used for compatibility, it contains a32 instructions
> which are not recognised by objtool when trying to analyse arm64
> object files. Thus, we add an exception to skip validation on this
> particular file.
> 
> Signed-off-by: Raphael Gault <raphael.gault@....com>
> Signed-off-by: Julien Thierry <jthierry@...hat.com>
> Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
> ---
>  arch/arm64/kernel/Makefile | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 986837d7ec82..c4f01bfe79b4 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -41,6 +41,9 @@ obj-$(CONFIG_COMPAT)			+= sys32.o signal32.o			\
>  					   sys_compat.o
>  obj-$(CONFIG_COMPAT)			+= sigreturn32.o
>  obj-$(CONFIG_KUSER_HELPERS)		+= kuser32.o
> +
> +OBJECT_FILES_NON_STANDARD_kuser32.o := y

File based skipping is depricated in the face of LTO and other link
target based objtool runs.

Please use function based blacklisting as per the previous patch.