Re: [RFC v1 09/10] book3s64/radix: Refactoring common kfence related functions

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 31/07/2024 à 09:56, Ritesh Harjani (IBM) a écrit :
> [Vous ne recevez pas souvent de courriers de ritesh.list@gmail.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> Both radix and hash on book3s requires to detect if kfence
> early init is enabled or not. Hash needs to disable kfence
> if early init is not enabled because with kfence the linear map is
> mapped using PAGE_SIZE rather than 16M mapping.
> We don't support multiple page sizes for slb entry used for kernel
> linear map in book3s64.
> 
> This patch refactors out the common functions required to detect kfence
> early init is enabled or not.
> 
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> ---
>   arch/powerpc/include/asm/kfence.h        |  2 ++
>   arch/powerpc/mm/book3s64/radix_pgtable.c | 12 ------------
>   arch/powerpc/mm/init-common.c            | 12 ++++++++++++
>   3 files changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/kfence.h b/arch/powerpc/include/asm/kfence.h
> index fab124ada1c7..5975688d8de1 100644
> --- a/arch/powerpc/include/asm/kfence.h
> +++ b/arch/powerpc/include/asm/kfence.h
> @@ -15,6 +15,8 @@
>   #define ARCH_FUNC_PREFIX "."
>   #endif
> 
> +extern bool kfence_early_init;
> +
>   #ifdef CONFIG_KFENCE
>   extern bool kfence_disabled;
> 
> diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
> index b0d927009af8..311e2112d782 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -363,18 +363,6 @@ static int __meminit create_physical_mapping(unsigned long start,
>   }
> 
>   #ifdef CONFIG_KFENCE
> -static bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL;
> -
> -static int __init parse_kfence_early_init(char *arg)
> -{
> -       int val;
> -
> -       if (get_option(&arg, &val))
> -               kfence_early_init = !!val;
> -       return 0;
> -}
> -early_param("kfence.sample_interval", parse_kfence_early_init);
> -
>   static inline phys_addr_t alloc_kfence_pool(void)
>   {
>          phys_addr_t kfence_pool;
> diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
> index 21131b96d209..259821a4db62 100644
> --- a/arch/powerpc/mm/init-common.c
> +++ b/arch/powerpc/mm/init-common.c
> @@ -33,6 +33,18 @@ bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
>   bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
>   #ifdef CONFIG_KFENCE
>   bool __ro_after_init kfence_disabled;
> +bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL;
> +static int __init parse_kfence_early_init(char *arg)

If I understand correctly, previously it was only for radix, now it is 
for every platform including PPC32 ?

> +{
> +       int val;
> +
> +       if (get_option(&arg, &val))
> +               kfence_early_init = !!val;
> +       return 0;
> +}
> +early_param("kfence.sample_interval", parse_kfence_early_init);
> +#else
> +bool __ro_after_init kfence_early_init;

I don't understand, why do you need that in the #else case ?

>   #endif
> 
>   static int __init parse_nosmep(char *p)
> --
> 2.45.2
>