powerpc: Rely on generic definition of hugepd_t and is_hugepd when unused

CONFIG_ARCH_HAS_HUGEPD is used to tell core mm when huge page
directories are used.

When they are not used, no need to provide hugepd_t or is_hugepd(),
just rely on the core mm fallback definition.

For that, change core mm behaviour so that CONFIG_ARCH_HAS_HUGEPD
is used instead of indirect is_hugepd macro existence.

powerpc being the only user of huge page directories, there is no
impact on other architectures.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/da81462d93069bb90fe5e762dd3283a644318937.1662543243.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/page.h

@@ -308,11 +308,6 @@ static inline bool pfn_valid(unsigned long pfn)
 #include <asm/pgtable-types.h>
 #endif
 
-
-#ifndef CONFIG_HUGETLB_PAGE
-#define is_hugepd(pdep)		(0)
-#endif /* CONFIG_HUGETLB_PAGE */
-
 struct page;
 extern void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
 extern void copy_user_page(void *to, void *from, unsigned long vaddr,

arch/powerpc/include/asm/pgtable-be-types.h

@@ -101,6 +101,7 @@ static inline bool pmd_xchg(pmd_t *pmdp, pmd_t old, pmd_t new)
 	return pmd_raw(old) == prev;
 }
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
 typedef struct { __be64 pdbe; } hugepd_t;
 #define __hugepd(x) ((hugepd_t) { cpu_to_be64(x) })
 
@@ -108,5 +109,6 @@ static inline unsigned long hpd_val(hugepd_t x)
 {
 	return be64_to_cpu(x.pdbe);
 }
+#endif
 
 #endif /* _ASM_POWERPC_PGTABLE_BE_TYPES_H */

arch/powerpc/include/asm/pgtable-types.h

@@ -83,11 +83,13 @@ static inline bool pte_xchg(pte_t *ptep, pte_t old, pte_t new)
 }
 #endif
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
 typedef struct { unsigned long pd; } hugepd_t;
 #define __hugepd(x) ((hugepd_t) { (x) })
 static inline unsigned long hpd_val(hugepd_t x)
 {
 	return x.pd;
 }
+#endif
 
 #endif /* _ASM_POWERPC_PGTABLE_TYPES_H */

include/linux/hugetlb.h

@@ -17,7 +17,7 @@ struct ctl_table;
 struct user_struct;
 struct mmu_gather;
 
-#ifndef is_hugepd
+#ifndef CONFIG_ARCH_HAS_HUGEPD
 typedef struct { unsigned long pd; } hugepd_t;
 #define is_hugepd(hugepd) (0)
 #define __hugepd(x) ((hugepd_t) { (x) })