1 files changed, 62 insertions, 0 deletions

diff --git a/include/asm-generic/pgtable-nop4d-hack.h b/include/asm-generic/pgtable-nop4d-hack.h
new file mode 100644
index 000000000000..752fb7511750
--- /dev/null
+++ b/include/asm-generic/pgtable-nop4d-hack.h
@@ -0,0 +1,62 @@
+#ifndef _PGTABLE_NOP4D_HACK_H
+#define _PGTABLE_NOP4D_HACK_H
+
+#ifndef __ASSEMBLY__
+#include <asm-generic/5level-fixup.h>
+
+#define __PAGETABLE_PUD_FOLDED
+
+/*
+ * Having the pud type consist of a pgd gets the size right, and allows
+ * us to conceptually access the pgd entry that this pud is folded into
+ * without casting.
+ */
+typedef struct { pgd_t pgd; } pud_t;
+
+#define PUD_SHIFT       PGDIR_SHIFT
+#define PTRS_PER_PUD    1
+#define PUD_SIZE        (1UL << PUD_SHIFT)
+#define PUD_MASK        (~(PUD_SIZE-1))
+
+/*
+ * The "pgd_xxx()" functions here are trivial for a folded two-level
+ * setup: the pud is never bad, and a pud always exists (as it's folded
+ * into the pgd entry)
+ */
+static inline int pgd_none(pgd_t pgd)           { return 0; }
+static inline int pgd_bad(pgd_t pgd)            { return 0; }
+static inline int pgd_present(pgd_t pgd)        { return 1; }
+static inline void pgd_clear(pgd_t *pgd)        { }
+#define pud_ERROR(pud)                          (pgd_ERROR((pud).pgd))
+
+#define pgd_populate(mm, pgd, pud)              do { } while (0)
+/*
+ * (puds are folded into pgds so this doesn't get actually called,
+ * but the define is needed for a generic inline function.)
+ */
+#define set_pgd(pgdptr, pgdval) set_pud((pud_t *)(pgdptr), (pud_t) { pgdval })
+
+static inline pud_t *pud_offset(pgd_t *pgd, unsigned long address)
+{
+        return (pud_t *)pgd;
+}
+
+#define pud_val(x)                              (pgd_val((x).pgd))
+#define __pud(x)                                ((pud_t) { __pgd(x) })
+
+#define pgd_page(pgd)                           (pud_page((pud_t){ pgd }))
+#define pgd_page_vaddr(pgd)                     (pud_page_vaddr((pud_t){ pgd }))
+
+/*
+ * allocating and freeing a pud is trivial: the 1-entry pud is
+ * inside the pgd, so has no extra memory associated with it.
+ */
+#define pud_alloc_one(mm, address)              NULL
+#define pud_free(mm, x)                         do { } while (0)
+#define __pud_free_tlb(tlb, x, a)               do { } while (0)
+
+#undef  pud_addr_end
+#define pud_addr_end(addr, end)                 (end)
+
+#endif /* __ASSEMBLY__ */
+#endif /* _PGTABLE_NOP4D_HACK_H */