Prior to this commit, pud_pfn was implemented with BUILD_BUG as the inline
function for 64-bit Book3S systems but is never included, as its
invocations in generic code are guarded by calls to pud_devmap which return
zero on such systems. A future patch will provide support for page table
checks, the generic code for which depends on a pud_pfn stub being
implemented, even while the patch will not interact with puds directly.

Remove the 64-bit Book3S stub and define pud_pfn to warn on all
platforms. pud_pfn may be defined properly on a per-platform basis
should it grow real usages in future.

Signed-off-by: Rohan McLure <redacted>
---
 arch/powerpc/include/asm/pgtable.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 0c0ffbe7a3b5..13f661831333 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h

@@ -213,6 +213,20 @@ static inline bool arch_supports_memmap_on_memory(unsigned long vmemmap_size)
 
 #endif /* CONFIG_PPC64 */
 
+/*
+ * Currently only consumed by page_table_check_pud_{set,clear}. Since clears
+ * and sets to page table entries at any level are done through
+ * page_table_check_pte_{set,clear}, provide stub implementation.
+ */
+#ifndef pud_pfn
+#define pud_pfn pud_pfn
+static inline int pud_pfn(pud_t pud)
+{
+	WARN_ONCE(1, "pud: platform does not use pud entries directly");
+	return 0;
+}
+#endif
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_PGTABLE_H */

-- 
2.44.0