Le 23/09/2022 à 08:08, 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/E 64-bit
> systems.
>
> Signed-off-by: Rohan McLure <rmcl...@linux.ibm.com>
> ---
> V2: Provide missing pud_user implementations, use p{u,m}d_is_leaf.
> ---
> diff --git a/arch/powerpc/include/asm/pgtable.h
> b/arch/powerpc/include/asm/pgtable.h
> index 36956fb440e1..69eed4e03da0 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -172,6 +172,39 @@ 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);
> +}
> +
> +#ifdef CONFIG_PPC64
> +
> +static inline bool pmd_user_accessible_page(pmd_t pmd)
> +{
> + return pmd_is_leaf(pmd) && pmd_present(pmd) && pmd_user(pmd);
> +}
> +
> +static inline bool pud_user_accessible_page(pud_t pud)
> +{
> + return pud_is_leaf(pud) && pud_present(pud) && pud_user(pud);
> +}
> +
> +#else
> +
> +static inline bool pmd_user_accessible_page(pmd_t pmd)
> +{
> + WARN(1, "pmd: multi-level paging unsupported on ppc32");
> + return false;
> +}
> +
> +static inline bool pud_user_accessible_page(pud_t pud)
> +{
> + WARN(1, "pud: multi-level paging unsupported on ppc32");
> + return false;
> +}
> +
> +#endif /* CONFIG_PPC64 */
> +
I can't see the point in this splitted implementation PPC64/PPC32.
The warning has no added value from my point of view.
And multi-level paging IS supported on PPC32, that's 2 level paging, the
PMD is folder into the PGD.
pmd_is_leaf() and pud_is_leaf() are PPC64 specific.
The following could be common to PPC32 and PPC64:
+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);
+}
+
pud_user() is defined in include/asm-generic/pgtable-nopmd.h for PPC32.
All you have to do is to define a stub pmd_user() for book3s/32 and
nohash/32.
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_POWERPC_PGTABLE_H */
