Messages in this thread Patch in this message | | | Date | Thu, 17 Mar 2022 19:00:04 +0000 | From | Catalin Marinas <> | Subject | Re: [PATCH -next 3/4] arm64: mm: add support for page table check |
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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
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