arm64: tlbflush: avoid flushing when fullmm == 1

The TLB gather code sets fullmm=1 when tearing down the entire address
space for an mm_struct on exit or execve. Given that the ASID allocator
will never re-allocate a dirty ASID, this flushing is not needed and can
simply be avoided in the flushing code.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index d6e6b66..ffdaea7 100644 (file)
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -37,17 +37,21 @@ static inline void __tlb_remove_table(void *_table)
 
 static inline void tlb_flush(struct mmu_gather *tlb)
 {
-       if (tlb->fullmm) {
-               flush_tlb_mm(tlb->mm);
-       } else {
-               struct vm_area_struct vma = { .vm_mm = tlb->mm, };
-               /*
-                * The intermediate page table levels are already handled by
-                * the __(pte|pmd|pud)_free_tlb() functions, so last level
-                * TLBI is sufficient here.
-                */
-               __flush_tlb_range(&vma, tlb->start, tlb->end, true);
-       }
+       struct vm_area_struct vma = { .vm_mm = tlb->mm, };
+
+       /*
+        * The ASID allocator will either invalidate the ASID or mark
+        * it as used.
+        */
+       if (tlb->fullmm)
+               return;
+
+       /*
+        * The intermediate page table levels are already handled by
+        * the __(pte|pmd|pud)_free_tlb() functions, so last level
+        * TLBI is sufficient here.
+        */
+       __flush_tlb_range(&vma, tlb->start, tlb->end, true);
 }
 
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,