Subject: Re: [PATCH 3/6] powerpc/64s: Use htab_convert_pte_flags() in hash__mark_rodata_ro()

From: Daniel Axtens <[email-masked]>
Date: Tue, 16 Feb 2021 16:50:49 +1100

Hi Michael,

> In hash__mark_rodata_ro() we pass the raw PP_RXXX value to
> hash__change_memory_range(). That has the effect of setting the key to
> zero, because PP_RXXX contains no key value.
>
> Fix it by using htab_convert_pte_flags(), which knows how to convert a
> pgprot into a pp value, including the key.

So far as I can tell by chasing the definitions around, this appears
to do what it claims to do.

So, for what it's worth:
Reviewed-by: Daniel Axtens <[email-masked]>

Kind regards,
Daniel

>
> Fixes: d94b827e89dc ("powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation")
> Signed-off-by: Michael Ellerman <[email-masked]>
> ---
>  arch/powerpc/mm/book3s64/hash_pgtable.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
> index 567e0c6b3978..03819c259f0a 100644
> --- a/arch/powerpc/mm/book3s64/hash_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
> @@ -428,12 +428,14 @@ static bool hash__change_memory_range(unsigned long start, unsigned long end,
>  
>  void hash__mark_rodata_ro(void)
>  {
> -	unsigned long start, end;
> +	unsigned long start, end, pp;
>  
>  	start = (unsigned long)_stext;
>  	end = (unsigned long)__init_begin;
>  
> -	WARN_ON(!hash__change_memory_range(start, end, PP_RXXX));
> +	pp = htab_convert_pte_flags(pgprot_val(PAGE_KERNEL_ROX), HPTE_USE_KERNEL_KEY);
> +
> +	WARN_ON(!hash__change_memory_range(start, end, pp));
>  }
>  
>  void hash__mark_initmem_nx(void)
> -- 
> 2.25.1