s390/mm: implement 5 level pages tables

Add the logic to upgrade the page table for a 64-bit process to
five levels. This increases the TASK_SIZE from 8PB to 16EB-4K.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 28 insertions, 5 deletions

diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index b7b779c40a5b..8ecc25e760fa 100644
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -166,15 +166,15 @@ static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr,
 	return 1;
 }
 
-static inline int gup_pud_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
+static inline int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr,
 		unsigned long end, int write, struct page **pages, int *nr)
 {
 	unsigned long next;
 	pud_t *pudp, pud;
 
-	pudp = (pud_t *) pgdp;
-	if ((pgd_val(pgd) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R2)
-		pudp = (pud_t *) pgd_deref(pgd);
+	pudp = (pud_t *) p4dp;
+	if ((p4d_val(p4d) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R2)
+		pudp = (pud_t *) p4d_deref(p4d);
 	pudp += pud_index(addr);
 	do {
 		pud = *pudp;
@@ -194,6 +194,29 @@ static inline int gup_pud_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
 	return 1;
 }
 
+static inline int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
+		unsigned long end, int write, struct page **pages, int *nr)
+{
+	unsigned long next;
+	p4d_t *p4dp, p4d;
+
+	p4dp = (p4d_t *) pgdp;
+	if ((pgd_val(pgd) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R1)
+		p4dp = (p4d_t *) pgd_deref(pgd);
+	p4dp += p4d_index(addr);
+	do {
+		p4d = *p4dp;
+		barrier();
+		next = p4d_addr_end(addr, end);
+		if (p4d_none(p4d))
+			return 0;
+		if (!gup_pud_range(p4dp, p4d, addr, next, write, pages, nr))
+			return 0;
+	} while (p4dp++, addr = next, addr != end);
+
+	return 1;
+}
+
 /*
  * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
  * back to the regular GUP.
@@ -228,7 +251,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 		next = pgd_addr_end(addr, end);
 		if (pgd_none(pgd))
 			break;
-		if (!gup_pud_range(pgdp, pgd, addr, next, write, pages, &nr))
+		if (!gup_p4d_range(pgdp, pgd, addr, next, write, pages, &nr))
 			break;
 	} while (pgdp++, addr = next, addr != end);
 	local_irq_restore(flags);