linux-kernel - [PATCH 06/11] change memory_is_poisoned

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Date:   Wed, 11 Oct 2017 16:22:22 +0800
From:   Abbott Liu <liuwenliang@...wei.com>
To:     <linux@...linux.org.uk>, <aryabinin@...tuozzo.com>,
        <liuwenliang@...wei.com>, <afzal.mohd.ma@...il.com>,
        <f.fainelli@...il.com>, <labbott@...hat.com>,
        <kirill.shutemov@...ux.intel.com>, <mhocko@...e.com>,
        <cdall@...aro.org>, <marc.zyngier@....com>,
        <catalin.marinas@....com>, <akpm@...ux-foundation.org>,
        <mawilcox@...rosoft.com>, <tglx@...utronix.de>,
        <thgarnie@...gle.com>, <keescook@...omium.org>, <arnd@...db.de>,
        <vladimir.murzin@....com>, <tixy@...aro.org>,
        <ard.biesheuvel@...aro.org>, <robin.murphy@....com>,
        <mingo@...nel.org>, <grygorii.strashko@...aro.org>
CC:     <glider@...gle.com>, <dvyukov@...gle.com>, <opendmb@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kasan-dev@...glegroups.com>,
        <linux-mm@...ck.org>, <jiazhenghua@...wei.com>,
        <dylix.dailei@...wei.com>, <zengweilin@...wei.com>,
        <heshaoliang@...wei.com>
Subject: [PATCH 06/11] change memory_is_poisoned_16 for aligned error

 Because arm instruction set don't support access the address which is
 not aligned, so must change memory_is_poisoned_16 for arm.

Cc:  Andrey Ryabinin <a.ryabinin@...sung.com>
Signed-off-by: Abbott Liu <liuwenliang@...wei.com>
---
 mm/kasan/kasan.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 12749da..e0e152b 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -149,6 +149,25 @@ static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
 	return memory_is_poisoned_1(addr + size - 1);
 }
 
+#ifdef CONFIG_ARM
+static __always_inline bool memory_is_poisoned_16(unsigned long addr)
+{
+	u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(shadow_addr[0] || shadow_addr[1])) return true;
+	else {
+		/*
+		 * 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);
+	}
+}
+
+#else
 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
 {
 	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
@@ -159,6 +178,7 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr)
 
 	return *shadow_addr;
 }
+#endif
 
 static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
 					size_t size)
-- 
2.9.0