linux-kernel - Re: [PATCH v1 2/2] LoongArch: Add ifdefs to fix LSX and LASX related issues

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Message-ID: <57818c31-c767-e8f4-2ea9-765e2dbbe1ba@loongson.cn>
Date: Thu, 22 Aug 2024 09:09:47 +0800
From: maobibo <maobibo@...ngson.cn>
To: Tiezhu Yang <yangtiezhu@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>, loongarch@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] LoongArch: Add ifdefs to fix LSX and LASX related
 issues



On 2024/8/21 下午6:07, Tiezhu Yang wrote:
> On 08/21/2024 09:12 AM, maobibo wrote:
>>
>>
>> On 2024/8/20 下午8:37, Tiezhu Yang wrote:
>>> There exist some issues when building kernel if CONFIG_CPU_HAS_LBT is 
>>> set
>>> but CONFIG_CPU_HAS_LSX and CONFIG_CPU_HAS_LASX are not set. In this 
>>> case,
>>> there are no definitions of _restore_lsx and _restore_lasx and there are
>>> also no definitions of kvm_restore_lsx and kvm_restore_lasx in fpu.S and
>>> switch.S respectively, just add some ifdefs to fix the issues.
> 
> ...
> 
>> It is hard to understand to put CONFIG_CPU_HAS_LASX inside
>> CONFIG_CPU_HAS_LBT, in general option CONFIG_CPU_HAS_LBT has nothing
>> with CONFIG_CPU_HAS_LASX.
>>
>> Would you like to add parameter func in macro fpu_restore_csr like this?
>>
>> --- a/arch/loongarch/include/asm/asmmacro.h
>> +++ b/arch/loongarch/include/asm/asmmacro.h
>> @@ -55,10 +55,11 @@
>>  #endif
>>         .endm
>>
>> -       .macro fpu_restore_csr thread tmp0 tmp1
>> +       .macro fpu_restore_csr thread tmp0 tmp1 func
>>         ldptr.w         \tmp0, \thread, THREAD_FCSR
>>         movgr2fcsr      fcsr0, \tmp0
>>  #ifdef CONFIG_CPU_HAS_LBT
>> +       STACK_FRAME_NON_STANDARD        \func
>>         /* TM bit is always 0 if LBT not supported */
>>         andi            \tmp0, \tmp0, FPU_CSR_TM
>>         beqz            \tmp0, 2f
>> @@ -282,10 +283,10 @@
>>         lsx_save_data           \thread, \tmp0
>>         .endm
> 
> For the record, I modified the related code as you suggested and tested 
> with various configs, it works well.
> 
> But as we discussed offline, these current changes are small relatively
> and the STACK_FRAME_NON_STANDARD related code may be removed if there
> is a proper possible way, so just leave it as is in my opinion.
Just be curious, what is the proper possible way to remove this, is it 
solved with new gcc/binutil version?  Do we plan to drop latest 
gcc/binutils support in near future only in order to remove these 
STACK_FRAME_NON_STANDARD code?

Regards
Bibo Mao
> 
> Thanks,
> Tiezhu
>