4.4-stable review patch. If anyone has any objections, please let me know.
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From: Shaokun Zhang zhangshaokun@hisilicon.com
commit 20c27a4270c775d7ed661491af8ac03264d60fc6 upstream.
__sync_icache_dcache unconditionally skips the cache maintenance for anonymous pages, under the assumption that flushing is only required in the presence of D-side aliases [see 7249b79f6b4cc ("arm64: Do not flush the D-cache for anonymous pages")].
Unfortunately, this breaks migration of anonymous pages holding self-modifying code, where userspace cannot be reasonably expected to reissue maintenance instructions in response to a migration.
This patch fixes the problem by removing the broken page_mapping(page) check from the cache syncing code, otherwise we may end up fetching and executing stale instructions from the PoU.
Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will.deacon@arm.com Cc: Mark Rutland mark.rutland@arm.com Cc: stable@vger.kernel.org Reviewed-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Shaokun Zhang zhangshaokun@hisilicon.com Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Sasha Levin sasha.levin@oracle.com Cc: Amanieu d'Antras amanieu@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/arm64/mm/flush.c | 4 ---- 1 file changed, 4 deletions(-)
--- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -70,10 +70,6 @@ void __sync_icache_dcache(pte_t pte, uns { struct page *page = pte_page(pte);
- /* no flushing needed for anonymous pages */ - if (!page_mapping(page)) - return; - if (!test_and_set_bit(PG_dcache_clean, &page->flags)) { __flush_dcache_area(page_address(page), PAGE_SIZE << compound_order(page));