| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 127/129] arm64: Avoid cache flushing in flush_dcache_page() | Date | Mon, 6 Jan 2014 14:39:16 -0800 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: Catalin Marinas <catalin.marinas@arm.com>
commit b5b6c9e9149d8a7c3f1d7b9d0c046c6184e1dd17 upstream.
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> Cc: Mark Brown <broonie@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/arm64/mm/flush.c | 22 ++++------------------ 1 file changed, 4 insertions(+), 18 deletions(-)
--- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -94,28 +94,14 @@ void __sync_icache_dcache(pte_t pte, uns } /* - * Ensure cache coherency between kernel mapping and userspace mapping of this - * page. + * This function is called when a page has been modified by the kernel. Mark + * it as dirty for later flushing when mapped in user space (if executable, + * see __sync_icache_dcache). */ void flush_dcache_page(struct page *page) { - struct address_space *mapping; - - /* - * 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 { + if (test_bit(PG_dcache_clean, &page->flags)) clear_bit(PG_dcache_clean, &page->flags); - } } EXPORT_SYMBOL(flush_dcache_page);
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