[RFC PATCH v3 06/16] powerpc/mm: Allow hugepages without hugepd

[Christophe Leroy <christophe.leroy@csgroup.eu>]

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.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v3:
- Prepare huge_pte_alloc() for full standard topology, not only for 2-level
- Reordered last part of huge_pte_alloc()
---
 arch/powerpc/include/asm/book3s/32/pgalloc.h |  2 --
 arch/powerpc/include/asm/hugetlb.h           | 10 ++----
 arch/powerpc/include/asm/nohash/pgtable.h    |  8 +++--
 arch/powerpc/mm/hugetlbpage.c                | 33 ++++++++++++++++++++
 arch/powerpc/mm/pgtable.c                    |  2 ++
 5 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/pgalloc.h b/arch/powerpc/include/asm/book3s/32/pgalloc.h
index dc5c039eb28e..dd4eb3063175 100644
--- a/arch/powerpc/include/asm/book3s/32/pgalloc.h
+++ b/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)
 {
diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index ea71f7245a63..79176a499763 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/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)
 {
 }
diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index 427db14292c9..ac3353f7f2ac 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/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
@@ -351,6 +351,10 @@ static inline int hugepd_ok(hugepd_t hpd)
 #endif
 }
 
+#define is_hugepd(hpd)		(hugepd_ok(hpd))
+#endif
+
+#ifdef CONFIG_HUGETLB_PAGE
 static inline int pmd_huge(pmd_t pmd)
 {
 	return 0;
@@ -360,8 +364,6 @@ static inline int pud_huge(pud_t pud)
 {
 	return 0;
 }
-
-#define is_hugepd(hpd)		(hugepd_ok(hpd))
 #endif
 
 int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 594a4b7b2ca2..20fad59ff9f5 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/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)
 {
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 10adef5967a3..c56593f568a2 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/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;
-- 
2.44.0