[PATCH v6 11/22] powerpc/book3s64/pkeys: Inherit correctly on fork.

[Christophe Leroy]

Le 25/11/2020 à 06:16, Aneesh Kumar K.V a écrit :
> Child thread.kuap value is inherited from the parent in copy_thread_tls. We still
> need to make sure when the child returns from a fork in the kernel we start with the kernel
> default AMR value.
> 
> Reviewed-by: Sandipan Das <sandipan at linux.ibm.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>   arch/powerpc/kernel/process.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index b6b8a845e454..733680de0ba4 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1768,6 +1768,17 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
>   		childregs->ppr = DEFAULT_PPR;
>   
>   	p->thread.tidr = 0;
> +#endif
> +	/*
> +	 * Run with the current AMR value of the kernel
> +	 */
> +#ifdef CONFIG_PPC_KUAP
> +	if (mmu_has_feature(MMU_FTR_KUAP))
> +		kregs->kuap = AMR_KUAP_BLOCKED;
> +#endif

Do we need that ifdef at all ?

Shouldn't mmu_has_feature(MMU_FTR_KUAP) be always false and get optimised out when CONFIG_PPC_KUAP 
is not defined ?

> +#ifdef CONFIG_PPC_KUEP
> +	if (mmu_has_feature(MMU_FTR_KUEP))
> +		kregs->iamr = AMR_KUEP_BLOCKED;

Same ?

>   #endif
>   	kregs->nip = ppc_function_entry(f);
>   	return 0;
>