On Thu, Mar 17, 2022 at 02:12:02PM +0000, Tong Tiangen wrote:
> @@ -628,6 +647,25 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
> #define pud_leaf(pud) pud_sect(pud)
> #define pud_valid(pud) pte_valid(pud_pte(pud))
>
> +#ifdef CONFIG_PAGE_TABLE_CHECK
> +static inline bool pte_user_accessible_page(pte_t pte)
> +{
> + return (pte_val(pte) & PTE_VALID) && (pte_val(pte) & PTE_USER);
> +}
There is another class of user mappings, execute-only, that have both
PTE_USER and PTE_UXN cleared. So this logic should be:
pte_valid(pte) && (pte_user(pte) || pte_user_exec(pte))
with pte_user() as:
#define pte_user(pte) (!!(pte_val(pte) & PTE_USER))
Do we care about PROT_NONE mappings here? They have the valid bit
cleared but pte_present() is true.
> +static inline bool pmd_user_accessible_page(pmd_t pmd)
> +{
> + return pmd_leaf(pmd) && (pmd_val(pmd) & PTE_VALID) &&
> + (pmd_val(pmd) & PTE_USER);
> +}
pmd_leaf() implies valid, so you can skip it if that's the aim.
Similar comment to the pte variant on execute-only and PROT_NONE
mappings.
--
Catalin
