linux-kernel - Re: [PATCH] powerpc: Force inlining of cpu_has

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Message-ID: <c3563256-7cde-3a42-dbf0-6ce31141ad30@csgroup.eu>
Date:   Fri, 12 Mar 2021 14:12:22 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc: Force inlining of cpu_has_feature() to avoid
 build failure



Le 10/03/2021 à 13:10, Christophe Leroy a écrit :
> The code relies on constant folding of cpu_has_feature() based
> on possible and always true values as defined per
> CPU_FTRS_ALWAYS and CPU_FTRS_POSSIBLE.
> 
> Build failure is encountered with for instance
> book3e_all_defconfig on kisskb in the AMDGPU driver which uses
> cpu_has_feature(CPU_FTR_VSX_COMP) to decide whether calling
> kernel_enable_vsx() or not.
> 
> The failure is due to cpu_has_feature() not being inlined with
> that configuration with gcc 4.9.
> 
> In the same way as commit acdad8fb4a15 ("powerpc: Force inlining of
> mmu_has_feature to fix build failure"), for inlining of
> cpu_has_feature().
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>

Fixes following build

http://kisskb.ellerman.id.au/kisskb/buildresult/14489391/

> ---
>   arch/powerpc/include/asm/cpu_has_feature.h | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/cpu_has_feature.h b/arch/powerpc/include/asm/cpu_has_feature.h
> index 7897d16e0990..727d4b321937 100644
> --- a/arch/powerpc/include/asm/cpu_has_feature.h
> +++ b/arch/powerpc/include/asm/cpu_has_feature.h
> @@ -7,7 +7,7 @@
>   #include <linux/bug.h>
>   #include <asm/cputable.h>
>   
> -static inline bool early_cpu_has_feature(unsigned long feature)
> +static __always_inline bool early_cpu_has_feature(unsigned long feature)
>   {
>   	return !!((CPU_FTRS_ALWAYS & feature) ||
>   		  (CPU_FTRS_POSSIBLE & cur_cpu_spec->cpu_features & feature));
> @@ -46,7 +46,7 @@ static __always_inline bool cpu_has_feature(unsigned long feature)
>   	return static_branch_likely(&cpu_feature_keys[i]);
>   }
>   #else
> -static inline bool cpu_has_feature(unsigned long feature)
> +static __always_inline bool cpu_has_feature(unsigned long feature)
>   {
>   	return early_cpu_has_feature(feature);
>   }
>