| From | Ben Hutchings <> | Date | Sat, 13 Aug 2016 18:42:51 +0100 | Subject | [PATCH 3.16 205/305] arm64: mm: remove page_mapping check in __sync_icache_dcache |
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3.16.37-rc1 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> 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> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- arch/arm64/mm/flush.c | 4 ---- 1 file changed, 4 deletions(-)
--- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -74,10 +74,6 @@ 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));
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