arm64: mm: remove page_mapping check in __sync_icache_dcache
authorShaokun Zhang <zhangshaokun@hisilicon.com>
Tue, 21 Jun 2016 07:32:57 +0000 (15:32 +0800)
committerWill Deacon <will.deacon@arm.com>
Tue, 21 Jun 2016 19:10:18 +0000 (20:10 +0100)
commit20c27a4270c775d7ed661491af8ac03264d60fc6
tree1cca6a11a7cb4fa984194821138b2cfe1113baf9
parent9ca4e58c20d5cb2a5bc378238188c71317aceac5
arm64: mm: remove page_mapping check in __sync_icache_dcache

__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>
arch/arm64/mm/flush.c