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Commit f342552b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Benjamin Herrenschmidt
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powerpc/mm: Make hpte_need_flush() safe for preemption 



hpte_need_flush() might be called outside of a preempt section
when manipulating the kernel page tables, so we need to use the
appopriate variants of per-cpu variable accesses. There should
be no risk of being in the middle of a batch and a context
switch will flush any pending batch.

[Patch extracted from a larger patch in Peter's preemptible
 mmu_gather series]

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent dd9c1549

arch/powerpc/mm/tlb_hash64.c

+3 −3
Original line number Diff line number Diff line
@@ -38,13 +38,11 @@ DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch); 
 * neesd to be flushed. This function will either perform the flush

 * immediately or will batch it up if the current CPU has an active

 * batch on it.

 *

 * Must be called from within some kind of spinlock/non-preempt region...

 */

void hpte_need_flush(struct mm_struct *mm, unsigned long addr,

		     pte_t *ptep, unsigned long pte, int huge)

{

	struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);

	struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);

	unsigned long vsid, vaddr;

	unsigned int psize;

	int ssize;
@@ -99,6 +97,7 @@ void hpte_need_flush(struct mm_struct *mm, unsigned long addr, 
	 */

	if (!batch->active) {

		flush_hash_page(vaddr, rpte, psize, ssize, 0);

		put_cpu_var(ppc64_tlb_batch);

		return;

	}
@@ -127,6 +126,7 @@ void hpte_need_flush(struct mm_struct *mm, unsigned long addr, 
	batch->index = ++i;

	if (i >= PPC64_TLB_BATCH_NR)

		__flush_tlb_pending(batch);

	put_cpu_var(ppc64_tlb_batch);

}



/*