[PATCH v6 7/7] powerpc/mm: Batch tlb flush when invalidating pte entries

[Aneesh Kumar K.V]

This will improve the task exit case, by batching tlb invalidates.

Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/radix.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/radix.h 
b/arch/powerpc/include/asm/book3s/64/radix.h
index c0d43766ec63..98a0aee8b148 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -140,13 +140,20 @@ static inline unsigned long radix__pte_update(struct 
mm_struct *mm,
                unsigned long new_pte;
 
                old_pte = __radix_pte_update(ptep, ~0, 0);
-               asm volatile("ptesync" : : : "memory");
                /*
                 * new value of pte
                 */
                new_pte = (old_pte | set) & ~clr;
-               radix__flush_tlb_pte(old_pte, mm, addr);
-               __radix_pte_update(ptep, 0, new_pte);
+               /*
+                * If we are trying to clear the pte, we can skip
+                * the below sequence and batch the tlb flush. The
+                * tlb flush batching is done by mmu gather code
+                */
+               if (new_pte) {
+                       asm volatile("ptesync" : : : "memory");
+                       radix__flush_tlb_pte(old_pte, mm, addr);
+                       __radix_pte_update(ptep, 0, new_pte);
+               }
        } else
                old_pte = __radix_pte_update(ptep, clr, set);
        asm volatile("ptesync" : : : "memory");
-- 
2.10.2