[RFC PATCH 3/6] arm: mm: Make mmu_gather aware of huge pages

[Steve Capper]

Huge pages on short descriptors are arranged as pairs of 1MB sections.
We need to be careful and ensure that the TLBs for both sections are
flushed when we tlb_add_flush on a huge pages.

This patch extends the tlb flush range to HPAGE_SIZE rather than
PAGE_SIZE when addresses belonging to huge page VMAs are added to
the flush range.

Signed-off-by: Steve Capper <steve.capper at linaro.org>
---
 arch/arm/include/asm/tlb.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/tlb.h b/arch/arm/include/asm/tlb.h
index 0baf7f0..f5ef8b8 100644
--- a/arch/arm/include/asm/tlb.h
+++ b/arch/arm/include/asm/tlb.h
@@ -81,10 +81,16 @@ static inline void tlb_flush(struct mmu_gather *tlb)
 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
 {
 	if (!tlb->fullmm) {
+		unsigned long size = PAGE_SIZE;
+
 		if (addr < tlb->range_start)
 			tlb->range_start = addr;
-		if (addr + PAGE_SIZE > tlb->range_end)
-			tlb->range_end = addr + PAGE_SIZE;
+
+		if (tlb->vma && is_vm_hugetlb_page(tlb->vma))
+			size = HPAGE_SIZE;
+
+		if (addr + size > tlb->range_end)
+			tlb->range_end = addr + size;
 	}
 }
 
-- 
1.8.1.4