powerpc/mm: allow hugepages without hugepd

In preparation of implementing huge pages on powerpc 8xx without hugepd,
enclose hugepd related code inside an ifdef CONFIG_ARCH_HAS_HUGEPD

This also allows removing some stubs.

Link: https://lkml.kernel.org/r/ada097ca8a4fa85a77f51719516ef2478800d77a.1719928057.git.christophe.leroy@csgroup.euSigned-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/powerpc/Kconfig

@@ -135,7 +135,6 @@ config PPC
 	select ARCH_HAS_DMA_MAP_DIRECT 		if PPC_PSERIES
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
-	select ARCH_HAS_HUGEPD			if HUGETLB_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_KERNEL_FPU_SUPPORT	if PPC64 && PPC_FPU
 	select ARCH_HAS_MEMBARRIER_CALLBACKS

arch/powerpc/include/asm/book3s/32/pgalloc.h

@@ -47,8 +47,6 @@ static inline void pgtable_free(void *table, unsigned index_size)
 	}
 }
 
-#define get_hugepd_cache_index(x)  (x)
-
 static inline void pgtable_free_tlb(struct mmu_gather *tlb,
 				    void *table, int shift)
 {

arch/powerpc/include/asm/hugetlb.h

@@ -30,10 +30,12 @@ static inline int is_hugepage_only_range(struct mm_struct *mm,
 }
 #define is_hugepage_only_range is_hugepage_only_range
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
 #define __HAVE_ARCH_HUGETLB_FREE_PGD_RANGE
 void hugetlb_free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
 			    unsigned long end, unsigned long floor,
 			    unsigned long ceiling);
+#endif
 
 #define __HAVE_ARCH_HUGE_PTEP_GET_AND_CLEAR
 static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
@@ -67,14 +69,6 @@ static inline void flush_hugetlb_page(struct vm_area_struct *vma,
 {
 }
 
-#define hugepd_shift(x) 0
-static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
-				    unsigned pdshift)
-{
-	return NULL;
-}
-
-
 static inline void __init gigantic_hugetlb_cma_reserve(void)
 {
 }

arch/powerpc/include/asm/nohash/pgtable.h

@@ -340,7 +340,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 
 #define pgprot_writecombine pgprot_noncached_wc
 
-#ifdef CONFIG_HUGETLB_PAGE
+#ifdef CONFIG_ARCH_HAS_HUGEPD
 static inline int hugepd_ok(hugepd_t hpd)
 {
 #ifdef CONFIG_PPC_8xx

arch/powerpc/mm/hugetlbpage.c

@@ -42,6 +42,7 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long s
 	return __find_linux_pte(mm->pgd, addr, NULL, NULL);
 }
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
 static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
 			   unsigned long address, unsigned int pdshift,
 			   unsigned int pshift, spinlock_t *ptl)
@@ -193,6 +194,36 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 
 	return hugepte_offset(*hpdp, addr, pdshift);
 }
+#else
+pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
+		      unsigned long addr, unsigned long sz)
+{
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	addr &= ~(sz - 1);
+
+	p4d = p4d_offset(pgd_offset(mm, addr), addr);
+	if (!mm_pud_folded(mm) && sz >= P4D_SIZE)
+		return (pte_t *)p4d;
+
+	pud = pud_alloc(mm, p4d, addr);
+	if (!pud)
+		return NULL;
+	if (!mm_pmd_folded(mm) && sz >= PUD_SIZE)
+		return (pte_t *)pud;
+
+	pmd = pmd_alloc(mm, pud, addr);
+	if (!pmd)
+		return NULL;
+
+	if (sz >= PMD_SIZE)
+		return (pte_t *)pmd;
+
+	return pte_alloc_huge(mm, pmd, addr);
+}
+#endif
 
 #ifdef CONFIG_PPC_BOOK3S_64
 /*
@@ -248,6 +279,7 @@ int __init alloc_bootmem_huge_page(struct hstate *h, int nid)
 	return __alloc_bootmem_huge_page(h, nid);
 }
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
 #ifndef CONFIG_PPC_BOOK3S_64
 #define HUGEPD_FREELIST_SIZE \
 	((PAGE_SIZE - sizeof(struct hugepd_freelist)) / sizeof(pte_t))
@@ -505,6 +537,7 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 		}
 	} while (addr = next, addr != end);
 }
+#endif
 
 bool __init arch_hugetlb_valid_size(unsigned long size)
 {

arch/powerpc/mm/pgtable.c

@@ -496,8 +496,10 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
 	if (!hpdp)
 		return NULL;
 
+#ifdef CONFIG_ARCH_HAS_HUGEPD
 	ret_pte = hugepte_offset(*hpdp, ea, pdshift);
 	pdshift = hugepd_shift(*hpdp);
+#endif
 out:
 	if (hpage_shift)
 		*hpage_shift = pdshift;

arch/powerpc/platforms/Kconfig.cputype

@@ -37,6 +37,7 @@ config PPC_85xx
 
 config PPC_8xx
 	bool "Freescale 8xx"
+	select ARCH_HAS_HUGEPD if HUGETLB_PAGE
 	select ARCH_SUPPORTS_HUGETLBFS
 	select FSL_SOC
 	select PPC_KUEP
@@ -98,6 +99,7 @@ config PPC_BOOK3S_64
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
+	select ARCH_HAS_HUGEPD if HUGETLB_PAGE
 	select ARCH_SUPPORTS_HUGETLBFS
 	select ARCH_SUPPORTS_NUMA_BALANCING
 	select HAVE_MOVE_PMD
@@ -290,6 +292,7 @@ config PPC_BOOK3S
 config PPC_E500
 	select FSL_EMB_PERFMON
 	bool
+	select ARCH_HAS_HUGEPD if HUGETLB_PAGE
 	select ARCH_SUPPORTS_HUGETLBFS if PHYS_64BIT || PPC64
 	select PPC_SMP_MUXED_IPI
 	select PPC_DOORBELL