Re: [PATCH v6 06/10] powerpc/64: Setup KUP on secondary CPUs

[Christophe Leroy <christophe.leroy@c-s.fr>]

Le 18/04/2019 à 08:51, Michael Ellerman a écrit :
> From: Russell Currey <ruscur@russell.cc>
> 
> Some platforms (i.e. Radix MMU) need per-CPU initialisation for KUP.
> 
> Any platforms that only want to do KUP initialisation once
> globally can just check to see if they're running on the boot CPU, or
> check if whatever setup they need has already been performed.
> 
> Note that this is only for 64-bit.
> 
> Signed-off-by: Russell Currey <ruscur@russell.cc>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
> 
> v6: setup_kup() can't be __init anymore.

As reported by the kbuild robot, then setup_kuap() and setup_kuep() 
can't be __init anymore in that case on the 8xx allthough the 8xx is not 
SMP. That is rather pitty since they are only used at init.

Why can't we keep setup_kup() __init ? Are secondary CPUs started after 
init section has been freed ?

Christophe

> ---
>   arch/powerpc/kernel/setup_64.c | 3 +++
>   arch/powerpc/mm/init-common.c  | 2 +-
>   2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index 6179c4200339..684e34493bf5 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -390,6 +390,9 @@ void early_setup_secondary(void)
>   	/* Initialize the hash table or TLB handling */
>   	early_init_mmu_secondary();
>   
> +	/* Perform any KUP setup that is per-cpu */
> +	setup_kup();
> +
>   	/*
>   	 * At this point, we can let interrupts switch to virtual mode
>   	 * (the MMU has been setup), so adjust the MSR in the PACA to
> diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
> index ecaedfff9992..6ea5607fc564 100644
> --- a/arch/powerpc/mm/init-common.c
> +++ b/arch/powerpc/mm/init-common.c
> @@ -45,7 +45,7 @@ static int __init parse_nosmap(char *p)
>   }
>   early_param("nosmap", parse_nosmap);
>   
> -void __init setup_kup(void)
> +void setup_kup(void)
>   {
>   	setup_kuep(disable_kuep);
>   	setup_kuap(disable_kuap);
>