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mmu_gather: move minimal range calculations into generic code

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On architectures with hardware broadcasting of TLB invalidation messages
, it makes sense to reduce the range of the mmu_gather structure when
unmapping page ranges based on the dirty address information passed to
tlb_remove_tlb_entry.

arm64 already does this by directly manipulating the start/end fields
of the gather structure, but this confuses the generic code which
does not expect these fields to change and can end up calculating
invalid, negative ranges when forcing a flush in zap_pte_range.

This patch moves the minimal range calculation out of the arm64 code
and into the generic implementation, simplifying zap_pte_range in the
process (which no longer needs to care about start/end, since they will
point to the appropriate ranges already). With the range being tracked
by core code, the need_flush flag is dropped in favour of checking that
the end of the range has actually been set.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Michal Simek <monstr@monstr.eu>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon
2014-10-29 10:03:09 +00:00
parent 63648dd20f
commit fb7332a9fe
7 changed files with 63 additions and 100 deletions
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30
mm/memory.c
View File

@@ -220,9 +220,6 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
/* Is it from 0 to ~0? */
tlb->fullmm = !(start | (end+1));
tlb->need_flush_all = 0;
tlb->start = start;
tlb->end = end;
tlb->need_flush = 0;
tlb->local.next = NULL;
tlb->local.nr = 0;
tlb->local.max = ARRAY_SIZE(tlb->__pages);
@@ -232,15 +229,20 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb->batch = NULL;
#endif
__tlb_reset_range(tlb);
}
static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
tlb->need_flush = 0;
if (!tlb->end)
return;
tlb_flush(tlb);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb_table_flush(tlb);
#endif
__tlb_reset_range(tlb);
}
static void tlb_flush_mmu_free(struct mmu_gather *tlb)
@@ -256,8 +258,6 @@ static void tlb_flush_mmu_free(struct mmu_gather *tlb)
void tlb_flush_mmu(struct mmu_gather *tlb)
{
if (!tlb->need_flush)
return;
tlb_flush_mmu_tlbonly(tlb);
tlb_flush_mmu_free(tlb);
}
@@ -292,7 +292,7 @@ int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
struct mmu_gather_batch *batch;
VM_BUG_ON(!tlb->need_flush);
VM_BUG_ON(!tlb->end);
batch = tlb->active;
batch->pages[batch->nr++] = page;
@@ -359,8 +359,6 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
{
struct mmu_table_batch **batch = &tlb->batch;
tlb->need_flush = 1;
/*
* When there's less then two users of this mm there cannot be a
* concurrent page-table walk.
@@ -1185,20 +1183,8 @@ again:
arch_leave_lazy_mmu_mode();
/* Do the actual TLB flush before dropping ptl */
if (force_flush) {
unsigned long old_end;
/*
* Flush the TLB just for the previous segment,
* then update the range to be the remaining
* TLB range.
*/
old_end = tlb->end;
tlb->end = addr;
if (force_flush)
tlb_flush_mmu_tlbonly(tlb);
tlb->start = addr;
tlb->end = old_end;
}
pte_unmap_unlock(start_pte, ptl);
/*