1 files changed, 302 insertions, 0 deletions
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
new file mode 100644
index 000000000000..6dc1aa7cefcc
--- /dev/null
+++ b/mm/kasan/kasan.c
@@ -0,0 +1,302 @@
+/*
+ * This file contains shadow memory manipulation code.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <a.ryabinin@samsung.com>
+ *
+ * Some of code borrowed from https://github.com/xairy/linux by
+ *        Andrey Konovalov <adech.fo@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/mm.h>
+#include <linux/printk.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/stacktrace.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/kasan.h>
+
+#include "kasan.h"
+
+/*
+ * Poisons the shadow memory for 'size' bytes starting from 'addr'.
+ * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
+ */
+static void kasan_poison_shadow(const void *address, size_t size, u8 value)
+{
+	void *shadow_start, *shadow_end;
+
+	shadow_start = kasan_mem_to_shadow(address);
+	shadow_end = kasan_mem_to_shadow(address + size);
+
+	memset(shadow_start, value, shadow_end - shadow_start);
+}
+
+void kasan_unpoison_shadow(const void *address, size_t size)
+{
+	kasan_poison_shadow(address, size, 0);
+
+	if (size & KASAN_SHADOW_MASK) {
+		u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
+		*shadow = size & KASAN_SHADOW_MASK;
+	}
+}
+
+
+/*
+ * All functions below always inlined so compiler could
+ * perform better optimizations in each of __asan_loadX/__assn_storeX
+ * depending on memory access size X.
+ */
+
+static __always_inline bool memory_is_poisoned_1(unsigned long addr)
+{
+	s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(shadow_value)) {
+		s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
+		return unlikely(last_accessible_byte >= shadow_value);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_2(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		if (memory_is_poisoned_1(addr + 1))
+			return true;
+
+		if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
+			return false;
+
+		return unlikely(*(u8 *)shadow_addr);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_4(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		if (memory_is_poisoned_1(addr + 3))
+			return true;
+
+		if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
+			return false;
+
+		return unlikely(*(u8 *)shadow_addr);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_8(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		if (memory_is_poisoned_1(addr + 7))
+			return true;
+
+		if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
+			return false;
+
+		return unlikely(*(u8 *)shadow_addr);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_16(unsigned long addr)
+{
+	u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
+
+	if (unlikely(*shadow_addr)) {
+		u16 shadow_first_bytes = *(u16 *)shadow_addr;
+		s8 last_byte = (addr + 15) & KASAN_SHADOW_MASK;
+
+		if (unlikely(shadow_first_bytes))
+			return true;
+
+		if (likely(!last_byte))
+			return false;
+
+		return memory_is_poisoned_1(addr + 15);
+	}
+
+	return false;
+}
+
+static __always_inline unsigned long bytes_is_zero(const u8 *start,
+					size_t size)
+{
+	while (size) {
+		if (unlikely(*start))
+			return (unsigned long)start;
+		start++;
+		size--;
+	}
+
+	return 0;
+}
+
+static __always_inline unsigned long memory_is_zero(const void *start,
+						const void *end)
+{
+	unsigned int words;
+	unsigned long ret;
+	unsigned int prefix = (unsigned long)start % 8;
+
+	if (end - start <= 16)
+		return bytes_is_zero(start, end - start);
+
+	if (prefix) {
+		prefix = 8 - prefix;
+		ret = bytes_is_zero(start, prefix);
+		if (unlikely(ret))
+			return ret;
+		start += prefix;
+	}
+
+	words = (end - start) / 8;
+	while (words) {
+		if (unlikely(*(u64 *)start))
+			return bytes_is_zero(start, 8);
+		start += 8;
+		words--;
+	}
+
+	return bytes_is_zero(start, (end - start) % 8);
+}
+
+static __always_inline bool memory_is_poisoned_n(unsigned long addr,
+						size_t size)
+{
+	unsigned long ret;
+
+	ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
+			kasan_mem_to_shadow((void *)addr + size - 1) + 1);
+
+	if (unlikely(ret)) {
+		unsigned long last_byte = addr + size - 1;
+		s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
+
+		if (unlikely(ret != (unsigned long)last_shadow ||
+			((last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
+			return true;
+	}
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
+{
+	if (__builtin_constant_p(size)) {
+		switch (size) {
+		case 1:
+			return memory_is_poisoned_1(addr);
+		case 2:
+			return memory_is_poisoned_2(addr);
+		case 4:
+			return memory_is_poisoned_4(addr);
+		case 8:
+			return memory_is_poisoned_8(addr);
+		case 16:
+			return memory_is_poisoned_16(addr);
+		default:
+			BUILD_BUG();
+		}
+	}
+
+	return memory_is_poisoned_n(addr, size);
+}
+
+
+static __always_inline void check_memory_region(unsigned long addr,
+						size_t size, bool write)
+{
+	struct kasan_access_info info;
+
+	if (unlikely(size == 0))
+		return;
+
+	if (unlikely((void *)addr <
+		kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
+		info.access_addr = (void *)addr;
+		info.access_size = size;
+		info.is_write = write;
+		info.ip = _RET_IP_;
+		kasan_report_user_access(&info);
+		return;
+	}
+
+	if (likely(!memory_is_poisoned(addr, size)))
+		return;
+
+	kasan_report(addr, size, write, _RET_IP_);
+}
+
+#define DEFINE_ASAN_LOAD_STORE(size)				\
+	void __asan_load##size(unsigned long addr)		\
+	{							\
+		check_memory_region(addr, size, false);		\
+	}							\
+	EXPORT_SYMBOL(__asan_load##size);			\
+	__alias(__asan_load##size)				\
+	void __asan_load##size##_noabort(unsigned long);	\
+	EXPORT_SYMBOL(__asan_load##size##_noabort);		\
+	void __asan_store##size(unsigned long addr)		\
+	{							\
+		check_memory_region(addr, size, true);		\
+	}							\
+	EXPORT_SYMBOL(__asan_store##size);			\
+	__alias(__asan_store##size)				\
+	void __asan_store##size##_noabort(unsigned long);	\
+	EXPORT_SYMBOL(__asan_store##size##_noabort)
+
+DEFINE_ASAN_LOAD_STORE(1);
+DEFINE_ASAN_LOAD_STORE(2);
+DEFINE_ASAN_LOAD_STORE(4);
+DEFINE_ASAN_LOAD_STORE(8);
+DEFINE_ASAN_LOAD_STORE(16);
+
+void __asan_loadN(unsigned long addr, size_t size)
+{
+	check_memory_region(addr, size, false);
+}
+EXPORT_SYMBOL(__asan_loadN);
+
+__alias(__asan_loadN)
+void __asan_loadN_noabort(unsigned long, size_t);
+EXPORT_SYMBOL(__asan_loadN_noabort);
+
+void __asan_storeN(unsigned long addr, size_t size)
+{
+	check_memory_region(addr, size, true);
+}
+EXPORT_SYMBOL(__asan_storeN);
+
+__alias(__asan_storeN)
+void __asan_storeN_noabort(unsigned long, size_t);
+EXPORT_SYMBOL(__asan_storeN_noabort);
+
+/* to shut up compiler complaints */
+void __asan_handle_no_return(void) {}
+EXPORT_SYMBOL(__asan_handle_no_return);