[PATCH] ia64: add support for folded p4d page tables

[Mike Rapoport <rppt@kernel.org>]

From: Mike Rapoport <rppt@linux.ibm.com>

Implement primitives necessary for the 4th level folding, add walks of p4d
level where appropriate, remove usage of __ARCH_USE_5LEVEL_HACK and replace
5level-fixup.h with pgtable-nop4d.h

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 arch/ia64/include/asm/pgalloc.h |  4 ++--
 arch/ia64/include/asm/pgtable.h | 17 ++++++++---------
 arch/ia64/mm/fault.c            |  7 ++++++-
 arch/ia64/mm/hugetlbpage.c      | 18 ++++++++++++------
 arch/ia64/mm/init.c             | 28 ++++++++++++++++++++++++----
 5 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/arch/ia64/include/asm/pgalloc.h b/arch/ia64/include/asm/pgalloc.h
index f4c491044882..2a3050345099 100644
--- a/arch/ia64/include/asm/pgalloc.h
+++ b/arch/ia64/include/asm/pgalloc.h
@@ -36,9 +36,9 @@ static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 
 #if CONFIG_PGTABLE_LEVELS = 4
 static inline void
-pgd_populate(struct mm_struct *mm, pgd_t * pgd_entry, pud_t * pud)
+p4d_populate(struct mm_struct *mm, p4d_t * p4d_entry, pud_t * pud)
 {
-	pgd_val(*pgd_entry) = __pa(pud);
+	p4d_val(*p4d_entry) = __pa(pud);
 }
 
 static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index d602e7c622db..c87f789bc914 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -283,12 +283,12 @@ extern unsigned long VMALLOC_END;
 #define pud_page(pud)			virt_to_page((pud_val(pud) + PAGE_OFFSET))
 
 #if CONFIG_PGTABLE_LEVELS = 4
-#define pgd_none(pgd)			(!pgd_val(pgd))
-#define pgd_bad(pgd)			(!ia64_phys_addr_valid(pgd_val(pgd)))
-#define pgd_present(pgd)		(pgd_val(pgd) != 0UL)
-#define pgd_clear(pgdp)			(pgd_val(*(pgdp)) = 0UL)
-#define pgd_page_vaddr(pgd)		((unsigned long) __va(pgd_val(pgd) & _PFN_MASK))
-#define pgd_page(pgd)			virt_to_page((pgd_val(pgd) + PAGE_OFFSET))
+#define p4d_none(p4d)			(!p4d_val(p4d))
+#define p4d_bad(p4d)			(!ia64_phys_addr_valid(p4d_val(p4d)))
+#define p4d_present(p4d)		(p4d_val(p4d) != 0UL)
+#define p4d_clear(p4dp)			(p4d_val(*(p4dp)) = 0UL)
+#define p4d_page_vaddr(p4d)		((unsigned long) __va(p4d_val(p4d) & _PFN_MASK))
+#define p4d_page(p4d)			virt_to_page((p4d_val(p4d) + PAGE_OFFSET))
 #endif
 
 /*
@@ -388,7 +388,7 @@ pgd_offset (const struct mm_struct *mm, unsigned long address)
 #if CONFIG_PGTABLE_LEVELS = 4
 /* Find an entry in the second-level page table.. */
 #define pud_offset(dir,addr) \
-	((pud_t *) pgd_page_vaddr(*(dir)) + (((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1)))
+	((pud_t *) p4d_page_vaddr(*(dir)) + (((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1)))
 #endif
 
 /* Find an entry in the third-level page table.. */
@@ -582,10 +582,9 @@ extern struct page *zero_page_memmap_ptr;
 
 
 #if CONFIG_PGTABLE_LEVELS = 3
-#define __ARCH_USE_5LEVEL_HACK
 #include <asm-generic/pgtable-nopud.h>
 #endif
-#include <asm-generic/5level-fixup.h>
+#include <asm-generic/pgtable-nop4d.h>
 #include <asm-generic/pgtable.h>
 
 #endif /* _ASM_IA64_PGTABLE_H */
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index c2f299fe9e04..ec994135cb74 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -29,6 +29,7 @@ static int
 mapped_kernel_page_is_present (unsigned long address)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *ptep, pte;
@@ -37,7 +38,11 @@ mapped_kernel_page_is_present (unsigned long address)
 	if (pgd_none(*pgd) || pgd_bad(*pgd))
 		return 0;
 
-	pud = pud_offset(pgd, address);
+	p4d = p4d_offset(pgd, address);
+	if (p4d_none(*p4d) || p4d_bad(*p4d))
+		return 0;
+
+	pud = pud_offset(p4d, address);
 	if (pud_none(*pud) || pud_bad(*pud))
 		return 0;
 
diff --git a/arch/ia64/mm/hugetlbpage.c b/arch/ia64/mm/hugetlbpage.c
index d16e419fd712..32352a73df0c 100644
--- a/arch/ia64/mm/hugetlbpage.c
+++ b/arch/ia64/mm/hugetlbpage.c
@@ -30,12 +30,14 @@ huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
 {
 	unsigned long taddr = htlbpage_to_page(addr);
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte = NULL;
 
 	pgd = pgd_offset(mm, taddr);
-	pud = pud_alloc(mm, pgd, taddr);
+	p4d = p4d_offset(pgd, taddr);
+	pud = pud_alloc(mm, p4d, taddr);
 	if (pud) {
 		pmd = pmd_alloc(mm, pud, taddr);
 		if (pmd)
@@ -49,17 +51,21 @@ huge_pte_offset (struct mm_struct *mm, unsigned long addr, unsigned long sz)
 {
 	unsigned long taddr = htlbpage_to_page(addr);
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte = NULL;
 
 	pgd = pgd_offset(mm, taddr);
 	if (pgd_present(*pgd)) {
-		pud = pud_offset(pgd, taddr);
-		if (pud_present(*pud)) {
-			pmd = pmd_offset(pud, taddr);
-			if (pmd_present(*pmd))
-				pte = pte_offset_map(pmd, taddr);
+		p4d = p4d_offset(pgd, addr);
+		if (p4d_present(*p4d)) {
+			pud = pud_offset(p4d, taddr);
+			if (pud_present(*pud)) {
+				pmd = pmd_offset(pud, taddr);
+				if (pmd_present(*pmd))
+					pte = pte_offset_map(pmd, taddr);
+			}
 		}
 	}
 
diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 58fd67068bac..bcdc78e97e6e 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -208,6 +208,7 @@ static struct page * __init
 put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -215,7 +216,10 @@ put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
 	pgd = pgd_offset_k(address);		/* note: this is NOT pgd_offset()! */
 
 	{
-		pud = pud_alloc(&init_mm, pgd, address);
+		p4d = p4d_alloc(&init_mm, pgd, address);
+		if (!p4d)
+			goto out;
+		pud = pud_alloc(&init_mm, p4d, address);
 		if (!pud)
 			goto out;
 		pmd = pmd_alloc(&init_mm, pud, address);
@@ -382,6 +386,7 @@ int vmemmap_find_next_valid_pfn(int node, int i)
 
 	do {
 		pgd_t *pgd;
+		p4d_t *p4d;
 		pud_t *pud;
 		pmd_t *pmd;
 		pte_t *pte;
@@ -392,7 +397,13 @@ int vmemmap_find_next_valid_pfn(int node, int i)
 			continue;
 		}
 
-		pud = pud_offset(pgd, end_address);
+		p4d = p4d_offset(pgd, end_address);
+		if (p4d_none(*p4d)) {
+			end_address += P4D_SIZE;
+			continue;
+		}
+
+		pud = pud_offset(p4d, end_address);
 		if (pud_none(*pud)) {
 			end_address += PUD_SIZE;
 			continue;
@@ -430,6 +441,7 @@ int __init create_mem_map_page_table(u64 start, u64 end, void *arg)
 	struct page *map_start, *map_end;
 	int node;
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -444,12 +456,20 @@ int __init create_mem_map_page_table(u64 start, u64 end, void *arg)
 	for (address = start_page; address < end_page; address += PAGE_SIZE) {
 		pgd = pgd_offset_k(address);
 		if (pgd_none(*pgd)) {
+			p4d = memblock_alloc_node(PAGE_SIZE, PAGE_SIZE, node);
+			if (!p4d)
+				goto err_alloc;
+			pgd_populate(&init_mm, pgd, p4d);
+		}
+		p4d = p4d_offset(pgd, address);
+
+		if (p4d_none(*p4d)) {
 			pud = memblock_alloc_node(PAGE_SIZE, PAGE_SIZE, node);
 			if (!pud)
 				goto err_alloc;
-			pgd_populate(&init_mm, pgd, pud);
+			p4d_populate(&init_mm, p4d, pud);
 		}
-		pud = pud_offset(pgd, address);
+		pud = pud_offset(p4d, address);
 
 		if (pud_none(*pud)) {
 			pmd = memblock_alloc_node(PAGE_SIZE, PAGE_SIZE, node);
-- 
2.24.0