sparc64: Encode huge PMDs using PTE encoding.

Now that we have 64-bits for PMDs we can stop using special encodings
for the huge PMD values, and just put real PTEs in there.

We allocate a _PAGE_PMD_HUGE bit to distinguish between plain PMDs and
huge ones.  It is the same for both 4U and 4V PTE layouts.

We also use _PAGE_SPECIAL to indicate the splitting state, since a
huge PMD cannot also be special.

All of the PMD --> PTE translation code disappears, and most of the
huge PMD bit modifications and tests just degenerate into the PTE
operations.  In particular USER_PGTABLE_CHECK_PMD_HUGE becomes
trivial.

As a side effect, normal PMDs don't shift the physical address around.
This also speeds up the page table walks in the TLB miss paths since
they don't have to do the shifts any more.

Another non-trivial aspect is that pte_modify() has to be changed
to preserve the _PAGE_PMD_HUGE bits as well as the page size field
of the pte.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 4 deletions

diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
index 97d1e56e9863..f1bd83019e71 100644
--- a/arch/sparc/mm/tlb.c
+++ b/arch/sparc/mm/tlb.c
@@ -161,8 +161,8 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	if (mm == &init_mm)
 		return;
 
-	if ((pmd_val(pmd) ^ pmd_val(orig)) & PMD_ISHUGE) {
-		if (pmd_val(pmd) & PMD_ISHUGE)
+	if ((pmd_val(pmd) ^ pmd_val(orig)) & _PAGE_PMD_HUGE) {
+		if (pmd_val(pmd) & _PAGE_PMD_HUGE)
 			mm->context.huge_pte_count++;
 		else
 			mm->context.huge_pte_count--;
@@ -178,10 +178,11 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	}
 
 	if (!pmd_none(orig)) {
-		bool exec = ((pmd_val(orig) & PMD_HUGE_EXEC) != 0);
+		pte_t orig_pte = __pte(pmd_val(orig));
+		bool exec = pte_exec(orig_pte);
 
 		addr &= HPAGE_MASK;
-		if (pmd_val(orig) & PMD_ISHUGE) {
+		if (pmd_trans_huge(orig)) {
 			tlb_batch_add_one(mm, addr, exec);
 			tlb_batch_add_one(mm, addr + REAL_HPAGE_SIZE, exec);
 		} else {