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arm64: avoid flushing icache multiple times on contiguous HugeTLB

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When a contiguous HugeTLB page is mapped, set_pte_at() will be called
CONT_PTES/CONT_PMDS times.  Therefore, __sync_icache_dcache() will
flush cache multiple times if the page is executable (to ensure
the I-D cache coherency).  However, the first flushing cache already
covers subsequent cache flush operations.  So only flusing cache
for the head page if it is a HugeTLB page to avoid redundant cache
flushing.  In the next patch, it is also depends on this change
since the tail vmemmap pages of HugeTLB is mapped with read-only
meanning only head page struct can be modified.

Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>
This commit is contained in:
Muchun Song
2022-03-07 21:42:34 +00:00
committed by Will Deacon
parent 2369f171d5
commit cf5a501d98
1 changed files with 7 additions and 0 deletions
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arch/arm64/mm/flush.c
+7
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@@ -52,6 +52,13 @@ void __sync_icache_dcache(pte_t pte)
{
struct page *page = pte_page(pte);
/*
* HugeTLB pages are always fully mapped, so only setting head page's
* PG_dcache_clean flag is enough.
*/
if (PageHuge(page))
page = compound_head(page);
if (!test_bit(PG_dcache_clean, &page->flags)) {
sync_icache_aliases((unsigned long)page_address(page),
(unsigned long)page_address(page) +