MIPS: Add 48-bit VA space (and 4-level page tables) for 4K pages.

Some users must have 4K pages while needing a 48-bit VA space size.
The cleanest way do do this is to go to a 4-level page table for this
case.  Each page table level using order-0 pages adds 9 bits to the
VA size (at 4K pages, so for four levels we get 9 * 4 + 12 == 48-bits.

For the 4K page size case only we add support functions for the PUD
level of the page table tree, also the TLB exception handlers get an
extra level of tree walk.

[david.daney@cavium.com: Forward port to v4.10.]
[david.daney@cavium.com: Forward port to v4.11.]

Signed-off-by: Alex Belits <alex.belits@cavium.com>
Signed-off-by: David Daney <david.daney@cavium.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Alex Belits <alex.belits@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15312/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/arch/mips/include/asm/pgalloc.h b/arch/mips/include/asm/pgalloc.h
index a8705f6c8180..a1bdb1ea5234 100644
--- a/arch/mips/include/asm/pgalloc.h
+++ b/arch/mips/include/asm/pgalloc.h
@@ -110,6 +110,32 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
 
 #endif
 
+#ifndef __PAGETABLE_PUD_FOLDED
+
+static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
+{
+	pud_t *pud;
+
+	pud = (pud_t *) __get_free_pages(GFP_KERNEL|__GFP_REPEAT, PUD_ORDER);
+	if (pud)
+		pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
+	return pud;
+}
+
+static inline void pud_free(struct mm_struct *mm, pud_t *pud)
+{
+	free_pages((unsigned long)pud, PUD_ORDER);
+}
+
+static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_t *pud)
+{
+	set_pgd(pgd, __pgd((unsigned long)pud));
+}
+
+#define __pud_free_tlb(tlb, x, addr)	pud_free((tlb)->mm, x)
+
+#endif /* __PAGETABLE_PUD_FOLDED */
+
 #define check_pgt_cache()	do { } while (0)
 
 extern void pagetable_init(void);