[PATCH v2 4/7] powerpc/64s/radix: make ptep_get_and_clear_full non-atomic for the full case
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2018-05-20 00:44:08
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
This matches other architectures, when we know there will be no further accesses to the address (e.g., for teardown), page table entries can be cleared non-atomically. The comments about NMMU are bogus: all MMU notifiers (including NMMU) are released at this point, with their TLBs flushed. An NMMU access at this point would be a bug. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/include/asm/book3s/64/radix.h | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index 705193e7192f..fcd92f9b6ec0 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h@@ -176,14 +176,8 @@ static inline pte_t radix__ptep_get_and_clear_full(struct mm_struct *mm, unsigned long old_pte; if (full) { - /* - * If we are trying to clear the pte, we can skip - * the DD1 pte update sequence and batch the tlb flush. The - * tlb flush batching is done by mmu gather code. We - * still keep the cmp_xchg update to make sure we get - * correct R/C bit which might be updated via Nest MMU. - */ - old_pte = __radix_pte_update(ptep, ~0ul, 0); + old_pte = pte_val(*ptep); + *ptep = __pte(0); } else old_pte = radix__pte_update(mm, addr, ptep, ~0ul, 0, 0);
--
2.17.0