Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b5b6c9e9 authored by Catalin Marinas's avatar Catalin Marinas
Browse files

arm64: Avoid cache flushing in flush_dcache_page() 



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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reported-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
parent d25749af

arch/arm64/mm/flush.c

+4 −18
Original line number Diff line number Diff line
@@ -94,29 +94,15 @@ void __sync_icache_dcache(pte_t pte, unsigned long addr) 
}



/*

 * 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);



/*