From c8793561f75a27eedc5928fe8b55e49ddb871eed Mon Sep 17 00:00:00 2001 From: Shaokun Zhang Date: Tue, 21 Jun 2016 15:32:57 +0800 Subject: [PATCH] arm64: mm: remove page_mapping check in __sync_icache_dcache 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 Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Catalin Marinas Signed-off-by: Shaokun Zhang Signed-off-by: Will Deacon [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- arch/arm64/mm/flush.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c index 0d64089d28b51..112cf05691c09 100644 --- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -74,10 +74,6 @@ void __sync_icache_dcache(pte_t pte, unsigned long addr) { 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)); -- 2.47.3