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

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Message-ID: <882d3aa3-24cf-9866-7e00-161e94893811@loongson.cn>
Date: Wed, 21 Aug 2024 18:07:29 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: maobibo <maobibo@...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 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.

Thanks,
Tiezhu