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arm64: Avoid cache flushing in flush_dcache_page()

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The flush_dcache_page() function is called when the kernel modified a
page cache page. Since the D-cache on AArch64 does not have aliases
this function can simply mark the page as dirty for later flushing via
set_pte_at()/__sync_icache_dcache() if the page is executable (to ensure
the I-D cache coherency).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Will Deacon <will.deacon@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Catalin Marinas 2013-05-01 12:23:05 +01:00
parent d25749afc6
commit b5b6c9e914
1 changed files with 4 additions and 18 deletions
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22
arch/arm64/mm/flush.c
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@ -94,28 +94,14 @@ void __sync_icache_dcache(pte_t pte, unsigned long addr)
} }
/* /*
* Ensure cache coherency between kernel mapping and userspace mapping of this * This function is called when a page has been modified by the kernel. Mark
* page. * it as dirty for later flushing when mapped in user space (if executable,
* see __sync_icache_dcache).
*/ */
void flush_dcache_page(struct page *page) void flush_dcache_page(struct page *page)
{ {
struct address_space *mapping; if (test_bit(PG_dcache_clean, &page->flags))
/*
* The zero page is never written to, so never has any dirty cache
* lines, and therefore never needs to be flushed.
*/
if (page == ZERO_PAGE(0))
return;
mapping = page_mapping(page);
if (mapping && mapping_mapped(mapping)) {
__flush_dcache_page(page);
__flush_icache_all();
set_bit(PG_dcache_clean, &page->flags);
} else {
clear_bit(PG_dcache_clean, &page->flags); clear_bit(PG_dcache_clean, &page->flags);
}
} }
EXPORT_SYMBOL(flush_dcache_page); EXPORT_SYMBOL(flush_dcache_page);