linux-kernel - Re: [PATCH v6 18/33] arm64: Change symbol type annotations

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Message-ID: <99883975-4fb7-b073-ac16-7a5474f5ac79@huawei.com>
Date:   Thu, 30 Jun 2022 10:41:42 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     Mark Brown <broonie@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
        <linuxppc-dev@...ts.ozlabs.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kbuild@...r.kernel.org>, <live-patching@...r.kernel.org>,
        <jpoimboe@...nel.org>, <peterz@...radead.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <masahiroy@...nel.org>, <michal.lkml@...kovi.net>,
        <ndesaulniers@...gle.com>, <mark.rutland@....com>,
        <pasha.tatashin@...een.com>, <rmk+kernel@...linux.org.uk>,
        <madvenka@...ux.microsoft.com>, <christophe.leroy@...roup.eu>,
        <daniel.thompson@...aro.org>
Subject: Re: [PATCH v6 18/33] arm64: Change symbol type annotations

Hi Mark,

Thanks for review!

On 2022/6/30 1:47, Mark Brown wrote:
> On Thu, Jun 23, 2022 at 09:49:02AM +0800, Chen Zhongjin wrote:
>> Code symbols not following the aarch64 procedure call convention should
>> be annotated with SYM_CODE_* instead of SYM_FUNC_*
>>
>> Mark relevant symbols as generic code symbols.
> 
>> -SYM_CODE_START(tramp_exit_native)
>> +SYM_CODE_START_LOCAL(tramp_exit_native)
>>  	tramp_exit
>>  SYM_CODE_END(tramp_exit_native)
>>  
>> -SYM_CODE_START(tramp_exit_compat)
>> +SYM_CODE_START_LOCAL(tramp_exit_compat)
> 
> The commit log says this is fixing things mistakenly lablelld SYM_FUNC
> but this bit of the actual change is making some symbols local.
> 

It makes sense. I'll remove this because whether this symbol is global makes few
difference here.

>> -SYM_FUNC_START_LOCAL(__create_page_tables)
>> +SYM_CODE_START_LOCAL(__create_page_tables)
>>  	mov	x28, lr
>>  
>>  	/*
>> @@ -389,7 +389,7 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
>>  	bl	dcache_inval_poc
>>  
>>  	ret	x28
>> -SYM_FUNC_END(__create_page_tables)
>> +SYM_CODE_END(__create_page_tables)
> 
> This is removed by Ard's recent refactoring, the others that are still
> present look valid enough (for things that don't use the stack IIRC they
> could be seen as conforming but equally this is all running in non
> standard environments).

You are right, for SYM_CODE_, objtool won't generate ORC automatically as other
normal functions, unless UNWIND_HINT is explicitly specified for non-standard
stack frames.