[PATCHv2 2/3] arm64: cpufeature: reorder cpus_have_{const,final}_cap()

[Will Deacon]

On Mon, Oct 26, 2020 at 01:49:30PM +0000, Mark Rutland wrote:
> In a subsequent patch we'll modify cpus_have_const_cap() to call
> cpus_have_final_cap(), and hence we need to define cpus_have_final_cap()
> first.
> 
> To make subsequent changes easier to follow, this patch reorders the two
> without making any other changes.
> 
> There should be no functional change as a result of this patch.

You say this...

> 
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: David Brazdil <dbrazdil at google.com>
> Cc: Marc Zyngier <maz at kernel.org>
> Cc: Will Deacon <will at kernel.org>
> ---
>  arch/arm64/include/asm/cpufeature.h | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index f7e7144af174c..5d18c54507e6a 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -428,35 +428,35 @@ static __always_inline bool __cpus_have_const_cap(int num)
>  }
>  
>  /*
> - * Test for a capability, possibly with a runtime check.
> + * Test for a capability without a runtime check.
>   *
> - * Before capabilities are finalized, this behaves as cpus_have_cap().
> + * Before capabilities are finalized, this will BUG().
>   * After capabilities are finalized, this is patched to avoid a runtime check.
>   *
>   * @num must be a compile-time constant.
>   */
> -static __always_inline bool cpus_have_const_cap(int num)
> +static __always_inline bool cpus_have_final_cap(int num)
>  {
>  	if (system_capabilities_finalized())
>  		return __cpus_have_const_cap(num);
>  	else
> -		return cpus_have_cap(num);
> +		BUG();

... but isn't the failure case of calling cpus_have_final_cap() early now
different? What does BUG() do at EL2 w/ nVHE?

Will