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

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Date:   Sat, 7 May 2022 14:35:41 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     Mark Rutland <mark.rutland@....com>
CC:     Peter Zijlstra <peterz@...radead.org>,
        <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>, <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 2022/5/6 18:06, Mark Rutland wrote:
>> However for my build kuser32.o content is in .text 
> 
> We should be able to move that into .rodata; it's never executed in kernel context.
> 
>> and there is only `vdso` symbol in .rodata without `vdso32`.
> 
> That means you're not building with CROSS_COMPILE_COMPAT, and so we can't build
> the 32-bit VDSO.
> 
>> And for defconfig the CONFIG_KUSER_HELPERS=y is on.
> 
> Yes.
> 
>> According to your description, it seems something wrong here?
> 
> Sorry, I was wrong about how we linked the kuser32 code.
> 
> I believe we can move that into .rodata by adding:
> 
> 	.section .rodata
> 
> ... to the start of that.

It works.

Thanks!

> I think that'd be a nice cleanup to do regardless of objtool.
> 
> Thanks,
> Mark.
> .