[PATCH] powerpc: Force inlining of cpu_has_feature() to avoid build failure

[PATCH] powerpc: Force inlining of cpu_has_feature() to avoid build failure

[Christophe Leroy]

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@csgroup.eu>
---
 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);
 }
-- 
2.25.0

Re: [PATCH] powerpc: Force inlining of cpu_has_feature() to avoid build failure

[Christophe Leroy]

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@csgroup.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);
>   }
> 

Re: [PATCH] powerpc: Force inlining of cpu_has_feature() to avoid build failure

[Michael Ellerman]

On Wed, 10 Mar 2021 12:10:34 +0000 (UTC), Christophe Leroy wrote:
> 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.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc: Force inlining of cpu_has_feature() to avoid build failure
      https://git.kernel.org/powerpc/c/eed5fae00593ab9d261a0c1ffc1bdb786a87a55a

cheers