From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752272AbbIOCDM (ORCPT ); Mon, 14 Sep 2015 22:03:12 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:47389 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbbIOCDL (ORCPT ); Mon, 14 Sep 2015 22:03:11 -0400 Message-ID: <55F77C52.3010101@huawei.com> Date: Tue, 15 Sep 2015 10:02:58 +0800 From: Xishi Qiu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Andrey Ryabinin , Andrew Morton , Andrey Konovalov , "Rusty Russell" , Michal Marek , "long.wanglong" CC: Linux MM , LKML Subject: [PATCH V3] kasan: use IS_ALIGNED in memory_is_poisoned_8() References: <55F62C65.7070100@huawei.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.25.179] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use IS_ALIGNED() to determine whether the shadow span two bytes. It generates less code and more readable. Also add some comments in shadow check functions. Please apply "kasan: fix last shadow judgement in memory_is_poisoned_16()" first. Signed-off-by: Xishi Qiu --- mm/kasan/kasan.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index 8da2114..d0a3af8 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -86,6 +86,11 @@ static __always_inline bool memory_is_poisoned_2(unsigned long addr) if (memory_is_poisoned_1(addr + 1)) return true; + /* + * If single shadow byte covers 2-byte access, we don't + * need to do anything more. Otherwise, test the first + * shadow byte. + */ if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0)) return false; @@ -103,6 +108,11 @@ static __always_inline bool memory_is_poisoned_4(unsigned long addr) if (memory_is_poisoned_1(addr + 3)) return true; + /* + * If single shadow byte covers 4-byte access, we don't + * need to do anything more. Otherwise, test the first + * shadow byte. + */ if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3)) return false; @@ -120,7 +130,12 @@ static __always_inline bool memory_is_poisoned_8(unsigned long addr) if (memory_is_poisoned_1(addr + 7)) return true; - if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7)) + /* + * If single shadow byte covers 8-byte access, we don't + * need to do anything more. Otherwise, test the first + * shadow byte. + */ + if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE))) return false; return unlikely(*(u8 *)shadow_addr); @@ -139,7 +154,12 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr) if (unlikely(shadow_first_bytes)) return true; - if (likely(IS_ALIGNED(addr, 8))) + /* + * If two shadow bytes covers 16-byte access, we don't + * need to do anything more. Otherwise, test the last + * shadow byte. + */ + if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE))) return false; return memory_is_poisoned_1(addr + 15); -- 2.0.0