linux-kernel - Re: [PATCH] arm64: armv8_deprecated: fix unused-function error

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Message-ID: <bb0ca8c3-0bb2-3baa-7ae6-06106e6207ad@huawei.com>
Date:   Thu, 24 Nov 2022 10:17:02 +0800
From:   Ren Zhijie <renzhijie2@...wei.com>
To:     Mark Rutland <mark.rutland@....com>
CC:     <catalin.marinas@....com>, <will@...nel.org>,
        <yusongping@...wei.com>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: armv8_deprecated: fix unused-function error


在 2022/11/23 19:01, Mark Rutland 写道:
> On Wed, Nov 23, 2022 at 10:06:03AM +0800, Ren Zhijie wrote:
>> 在 2022/11/23 0:48, Mark Rutland 写道:
>>> On Tue, Nov 22, 2022 at 03:20:10AM +0000, Ren Zhijie wrote:
>>>> If CONFIG_SWP_EMULATION is not set and
>>>> CONFIG_CP15_BARRIER_EMULATION is not set,
>>>> aarch64-linux-gnu complained about unused-function :
>>>>
>>>> arch/arm64/kernel/armv8_deprecated.c:67:21: error: ‘aarch32_check_condition’ defined but not used [-Werror=unused-function]
>>>>    static unsigned int aarch32_check_condition(u32 opcode, u32 psr)
>>>>                        ^~~~~~~~~~~~~~~~~~~~~~~
>>>> cc1: all warnings being treated as errors
>>>>
>>>> To fix this error, warp the definition of
>>>> aarch32_check_condition() by defined(CONFIG_SWP_EMULATION) ||
>>>> defined(CONFIG_CP15_BARRIER_EMULATION)
>>>>
>>>> Fixes: 0c5f416219da ("arm64: armv8_deprecated: move aarch32 helper earlier")
>>> This also depends on building with additional options to turn warnings into
>>> errors, no?
>> No，i just run the normal command as follow:
>>
>> make ARCH="arm64" CROSS_COMPILE="aarch64-linux-gnu-"
> I think you must also have CONFIG_WERROR enabled?
>
> Just building defconfig + CONFIG_ARMV8_DEPRECATED=y gives me a warning, but not
> an error, and the kernel builds just fine.
>
> So this is a problem to fix, and I appreciate that in test configs this might
> be broken, but it's not a full build-time failure for most users.

I get it, thanks a lot!

Thanks,

Ren

> Thanks,
> Mark.
>
>>>> Signed-off-by: Ren Zhijie <renzhijie2@...wei.com>
>>>> ---
>>>>    arch/arm64/kernel/armv8_deprecated.c | 2 ++
>>>>    1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
>>>> index ed0788cf6bbb..3f29ceb6653a 100644
>>>> --- a/arch/arm64/kernel/armv8_deprecated.c
>>>> +++ b/arch/arm64/kernel/armv8_deprecated.c
>>>> @@ -64,6 +64,7 @@ struct insn_emulation {
>>>>    #define	ARM_OPCODE_CONDITION_UNCOND	0xf
>>>> +#if defined(CONFIG_SWP_EMULATION) || defined(CONFIG_CP15_BARRIER_EMULATION)
>>>>    static unsigned int aarch32_check_condition(u32 opcode, u32 psr)
>>>>    {
>>>>    	u32 cc_bits  = opcode >> 28;
>>>> @@ -76,6 +77,7 @@ static unsigned int aarch32_check_condition(u32 opcode, u32 psr)
>>>>    	}
>>>>    	return ARM_OPCODE_CONDTEST_UNCOND;
>>>>    }
>>>> +#endif
>>> Could we mark this as '__maybe_unused' or 'inline' instead? I think that's
>>> preferable to the ifdeferry.
>> sure, i will use __maybe_unused in v2.
>>
>> Thanks,
>>
>> Ren.
>>
>>> Thanks,
>>> Mark.
>>>
>>>>    #ifdef CONFIG_SWP_EMULATION
>>>>    /*
>>>> -- 
>>>> 2.17.1
>>>>
>>> .
> .