On Thu, May 23, 2019 at 04:03:16PM +0100, Robin Murphy wrote: > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index 2c41b04708fe..a6378625d47c 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -90,6 +90,7 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; > #define pte_write(pte) (!!(pte_val(pte) & PTE_WRITE)) > #define pte_user_exec(pte) (!(pte_val(pte) & PTE_UXN)) > #define pte_cont(pte) (!!(pte_val(pte) & PTE_CONT)) > +#define pte_devmap(pte) (!!(pte_val(pte) & PTE_DEVMAP)) > > #define pte_cont_addr_end(addr, end) \ > ({ unsigned long __boundary = ((addr) + CONT_PTE_SIZE) & CONT_PTE_MASK; \ > @@ -217,6 +218,11 @@ static inline pmd_t pmd_mkcont(pmd_t pmd) > return __pmd(pmd_val(pmd) | PMD_SECT_CONT); > } > > +static inline pte_t pte_mkdevmap(pte_t pte) > +{ > + return set_pte_bit(pte, __pgprot(PTE_DEVMAP)); > +} > + > static inline void set_pte(pte_t *ptep, pte_t pte) > { > WRITE_ONCE(*ptep, pte); > @@ -381,6 +387,9 @@ static inline int pmd_protnone(pmd_t pmd) > > #define pmd_mkhuge(pmd) (__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT)) > > +#define pmd_devmap(pmd) pte_devmap(pmd_pte(pmd)) > +#define pmd_mkdevmap(pmd) pte_pmd(pte_mkdevmap(pmd_pte(pmd))) > + > #define __pmd_to_phys(pmd) __pte_to_phys(pmd_pte(pmd)) > #define __phys_to_pmd_val(phys) __phys_to_pte_val(phys) > #define pmd_pfn(pmd) ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT) > @@ -537,6 +546,11 @@ static inline phys_addr_t pud_page_paddr(pud_t pud) > return __pud_to_phys(pud); > } > > +static inline int pud_devmap(pud_t pud) > +{ > + return 0; > +} > + > /* Find an entry in the second-level page table. */ > #define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1)) > > @@ -624,6 +638,11 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd) > > #define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd_val(pgd)) > > +static inline int pgd_devmap(pgd_t pgd) > +{ > + return 0; > +} I think you need to guard this and pXd_devmap() with CONFIG_TRANSPARENT_HUGEPAGE, otherwise you'll conflict with the dummy definitions in mm.h and the build will fail. Will