On Fri, Nov 10, 2023 at 08:19:23PM +0530, Aneesh Kumar K.V wrote: > > Hello, > > Some architectures can now support EXEC_ONLY mappings and I am wondering > what get_user_pages() on those addresses should return. -EPERM > Earlier PROT_EXEC implied PROT_READ and pte_access_permitted() > returned true for that. But arm64 does have this explicit comment > that says > > /* > * p??_access_permitted() is true for valid user mappings (PTE_USER > * bit set, subject to the write permission check). For execute-only > * mappings, like PROT_EXEC with EPAN (both PTE_USER and PTE_UXN bits > * not set) must return false. PROT_NONE mappings do not have the > * PTE_VALID bit set. > */ > > Is that correct? We should be able to get struct page for PROT_EXEC > mappings? If the memory is unreadable then providing a back door through O_DIRECT and everthing else to read it sounds wrong to me. If there is some case where a get_user_pages caller is exec-only compatible then a new FOLL_EXEC flag to permit it would make sense. Jason
