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powerpc/mm: Make hpte_need_flush() safe for preemption

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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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Peter Zijlstra 2011-02-24 10:47:32 +00:00 committed by Benjamin Herrenschmidt
parent dd9c1549ed
commit f342552b91
1 changed files with 3 additions and 3 deletions
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6
arch/powerpc/mm/tlb_hash64.c
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@ -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 * neesd to be flushed. This function will either perform the flush
* immediately or will batch it up if the current CPU has an active * immediately or will batch it up if the current CPU has an active
* batch on it. * 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, void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, unsigned long pte, int huge) 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 long vsid, vaddr;
unsigned int psize; unsigned int psize;
int ssize; int ssize;
@ -99,6 +97,7 @@ void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
*/ */
if (!batch->active) { if (!batch->active) {
flush_hash_page(vaddr, rpte, psize, ssize, 0); flush_hash_page(vaddr, rpte, psize, ssize, 0);
put_cpu_var(ppc64_tlb_batch);
return; return;
} }
@ -127,6 +126,7 @@ void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
batch->index = ++i; batch->index = ++i;
if (i >= PPC64_TLB_BATCH_NR) if (i >= PPC64_TLB_BATCH_NR)
__flush_tlb_pending(batch); __flush_tlb_pending(batch);
put_cpu_var(ppc64_tlb_batch);
} }
/* /*