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SubjectRe: [RFC v6 27/62] powerpc: helper to validate key-access permissions of a pte
Date
Ram Pai <linuxram@us.ibm.com> writes:

> helper function that checks if the read/write/execute is allowed
> on the pte.
>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> ---
> arch/powerpc/include/asm/book3s/64/pgtable.h | 4 +++
> arch/powerpc/include/asm/pkeys.h | 12 +++++++++
> arch/powerpc/mm/pkeys.c | 33 ++++++++++++++++++++++++++
> 3 files changed, 49 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 30d7f55..0056e58 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -472,6 +472,10 @@ static inline void write_uamor(u64 value)
> mtspr(SPRN_UAMOR, value);
> }
>
> +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> +extern bool arch_pte_access_permitted(u64 pte, bool write, bool execute);
> +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> +
> #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
> static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
> unsigned long addr, pte_t *ptep)
> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> index bbb5d85..7a9aade 100644
> --- a/arch/powerpc/include/asm/pkeys.h
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -53,6 +53,18 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
> ((pteflags & H_PAGE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL));
> }
>
> +static inline u16 pte_to_pkey_bits(u64 pteflags)
> +{
> + if (!pkey_inited)
> + return 0x0UL;

Do we really need that above check ? We should always find it
peky_inited to be set.

> +
> + return (((pteflags & H_PAGE_PKEY_BIT0) ? 0x10 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT1) ? 0x8 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT2) ? 0x4 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT3) ? 0x2 : 0x0UL) |
> + ((pteflags & H_PAGE_PKEY_BIT4) ? 0x1 : 0x0UL));
> +}
> +


-aneesh

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