On 19/12/2019 11:43, Michael Ellerman wrote: > Steven Price <steven.price@xxxxxxx> writes: >> Exposing the pud/pgd levels of the page tables to walk_page_range() means >> we may come across the exotic large mappings that come with large areas >> of contiguous memory (such as the kernel's linear map). >> >> For architectures that don't provide all p?d_leaf() macros, provide >> generic do nothing default that are suitable where there cannot be leaf >> pages at that level. Futher patches will add implementations for >> individual architectures. >> >> The name p?d_leaf() is chosen to minimize the confusion with existing >> uses of "large" pages and "huge" pages which do not necessary mean that >> the entry is a leaf (for example it may be a set of contiguous entries >> that only take 1 TLB slot). For the purpose of walking the page tables >> we don't need to know how it will be represented in the TLB, but we do >> need to know for sure if it is a leaf of the tree. >> >> Signed-off-by: Steven Price <steven.price@xxxxxxx> >> Acked-by: Mark Rutland <mark.rutland@xxxxxxx> >> --- >> include/asm-generic/pgtable.h | 20 ++++++++++++++++++++ >> 1 file changed, 20 insertions(+) >> >> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h >> index 798ea36a0549..e2e2bef07dd2 100644 >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -1238,4 +1238,24 @@ static inline bool arch_has_pfn_modify_check(void) >> #define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) >> #endif >> >> +/* >> + * p?d_leaf() - true if this entry is a final mapping to a physical address. >> + * This differs from p?d_huge() by the fact that they are always available (if >> + * the architecture supports large pages at the appropriate level) even >> + * if CONFIG_HUGETLB_PAGE is not defined. >> + * Only meaningful when called on a valid entry. >> + */ >> +#ifndef pgd_leaf >> +#define pgd_leaf(x) 0 >> +#endif >> +#ifndef p4d_leaf >> +#define p4d_leaf(x) 0 >> +#endif >> +#ifndef pud_leaf >> +#define pud_leaf(x) 0 >> +#endif >> +#ifndef pmd_leaf >> +#define pmd_leaf(x) 0 >> +#endif > > Any reason you made these #defines rather than static inlines? No strong reason - but these have to be #defines in the arch overrides so the #ifndef works, so I was being consistent here. I guess a static inline might avoid warnings although I haven't seen any. Steve
