[PATCH v7 6/7] powerpc: mm: Add p{te,md,ud}_user_accessible_page helpers

[Christophe Leroy]

Le 15/02/2023 à 03:01, Rohan McLure a écrit :
> Add the following helpers for detecting whether a page table entry
> is a leaf and is accessible to user space.
> 
>   * pte_user_accessible_page
>   * pmd_user_accessible_page
>   * pud_user_accessible_page
> 
> Also implement missing pud_user definitions for both Book3S/nohash 64-bit
> systems, and pmd_user for Book3S/nohash 32-bit systems.
> 
> Signed-off-by: Rohan McLure <rmclure at linux.ibm.com>

Reviewed-by: Christophe Leroy <christophe.leroy at csgroup.eu>

> ---
> V2: Provide missing pud_user implementations, use p{u,m}d_is_leaf.
> V3: Provide missing pmd_user implementations as stubs in 32-bit.
> V4: Use pmd_leaf, pud_leaf, and define pmd_user for 32 Book3E with
> static inline method rather than macro.
> ---
>   arch/powerpc/include/asm/book3s/32/pgtable.h |  4 ++++
>   arch/powerpc/include/asm/book3s/64/pgtable.h | 10 ++++++++++
>   arch/powerpc/include/asm/nohash/32/pgtable.h |  5 +++++
>   arch/powerpc/include/asm/nohash/64/pgtable.h | 10 ++++++++++
>   arch/powerpc/include/asm/pgtable.h           | 15 +++++++++++++++
>   5 files changed, 44 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
> index a090cb13a4a0..afd672e84791 100644
> --- a/arch/powerpc/include/asm/book3s/32/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
> @@ -516,6 +516,10 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
>   	return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
>   }
>   
> +static inline bool pmd_user(pmd_t pmd)
> +{
> +	return 0;
> +}
>   
>   
>   /* This low level function performs the actual PTE insertion
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index df5ee856444d..a6ed93d01da1 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -538,6 +538,16 @@ static inline bool pte_user(pte_t pte)
>   	return !(pte_raw(pte) & cpu_to_be64(_PAGE_PRIVILEGED));
>   }
>   
> +static inline bool pmd_user(pmd_t pmd)
> +{
> +	return !(pmd_raw(pmd) & cpu_to_be64(_PAGE_PRIVILEGED));
> +}
> +
> +static inline bool pud_user(pud_t pud)
> +{
> +	return !(pud_raw(pud) & cpu_to_be64(_PAGE_PRIVILEGED));
> +}
> +
>   #define pte_access_permitted pte_access_permitted
>   static inline bool pte_access_permitted(pte_t pte, bool write)
>   {
> diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
> index 70edad44dff6..d953533c56ff 100644
> --- a/arch/powerpc/include/asm/nohash/32/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
> @@ -209,6 +209,11 @@ static inline void pmd_clear(pmd_t *pmdp)
>   	*pmdp = __pmd(0);
>   }
>   
> +static inline bool pmd_user(pmd_t pmd)
> +{
> +	return false;
> +}
> +
>   /*
>    * PTE updates. This function is called whenever an existing
>    * valid PTE is updated. This does -not- include set_pte_at()
> diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
> index d391a45e0f11..14e69ebad31f 100644
> --- a/arch/powerpc/include/asm/nohash/64/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
> @@ -123,6 +123,11 @@ static inline pte_t pmd_pte(pmd_t pmd)
>   	return __pte(pmd_val(pmd));
>   }
>   
> +static inline bool pmd_user(pmd_t pmd)
> +{
> +	return (pmd_val(pmd) & _PAGE_USER) == _PAGE_USER;
> +}
> +
>   #define pmd_none(pmd)		(!pmd_val(pmd))
>   #define	pmd_bad(pmd)		(!is_kernel_addr(pmd_val(pmd)) \
>   				 || (pmd_val(pmd) & PMD_BAD_BITS))
> @@ -164,6 +169,11 @@ static inline pte_t pud_pte(pud_t pud)
>   	return __pte(pud_val(pud));
>   }
>   
> +static inline bool pud_user(pud_t pud)
> +{
> +	return (pud_val(pud) & _PAGE_USER) == _PAGE_USER;
> +}
> +
>   static inline pud_t pte_pud(pte_t pte)
>   {
>   	return __pud(pte_val(pte));
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index ad0829f816e9..b76fdb80b6c9 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -167,6 +167,21 @@ static inline int pud_pfn(pud_t pud)
>   }
>   #endif
>   
> +static inline bool pte_user_accessible_page(pte_t pte)
> +{
> +	return pte_present(pte) && pte_user(pte);
> +}
> +
> +static inline bool pmd_user_accessible_page(pmd_t pmd)
> +{
> +	return pmd_leaf(pmd) && pmd_present(pmd) && pmd_user(pmd);
> +}
> +
> +static inline bool pud_user_accessible_page(pud_t pud)
> +{
> +	return pud_leaf(pud) && pud_present(pud) && pud_user(pud);
> +}
> +
>   #endif /* __ASSEMBLY__ */
>   
>   #endif /* _ASM_POWERPC_PGTABLE_H */