[PATCH v8 10/20] mm: Add generic p?d_large() macros

Steven Price
2019-04-03T14:18:01Z

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 p?d_large() macros, provide generic
does nothing defaults.

Signed-off-by: Steven Price <steven.price@arm.com>
---
include/asm-generic/pgtable.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index fa782fba51ee..9c5d0f73db67 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1186,4 +1186,23 @@ static inline bool arch_has_pfn_modify_check(void)
#define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED)
#endif

+/*
+ * p?d_large() - 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.
+ */
+#ifndef pgd_large
+#define pgd_large(x) 0
+#endif
+#ifndef p4d_large
+#define p4d_large(x) 0
+#endif
+#ifndef pud_large
+#define pud_large(x) 0
+#endif
+#ifndef pmd_large
+#define pmd_large(x) 0
+#endif
+
#endif /* _ASM_GENERIC_PGTABLE_H */
--
2.20.1