Define KASAN_SHADOW_OFFSET,KASAN_SHADOW_START and KASAN_SHADOW_END for arm
kernel address sanitizer.
+----+ 0xffffffff
| |
| |
| |
+----+ CONFIG_PAGE_OFFSET
| |\
| | |-> module virtual address space area.
| |/
+----+ MODULE_VADDR = KASAN_SHADOW_END
| |\
| | |-> the shadow area of kernel virtual address.
| |/
+----+ TASK_SIZE(start of kernel space) = KASAN_SHADOW_START the shadow address of MODULE_VADDR
| |\
| | ---------------------+
| | |
+ + KASAN_SHADOW_OFFSET |-> the user space area. Kernel address sanitizer do not use this space.
| | |
| | ---------------------+
| |/
------ 0
1)KASAN_SHADOW_OFFSET:
This value is used to map an address to the corresponding shadow address by the
following formula:
shadow_addr = (address >> 3) + KASAN_SHADOW_OFFSET;
2)KASAN_SHADOW_START
This value is the MODULE_VADDR's shadow address. It is the start of kernel virtual
space.
3) KASAN_SHADOW_END
This value is the 0x100000000's shadow address. It is the end of kernel address
sanitizer's shadow area. It is also the start of the module area.
Cc: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
---
arch/arm/include/asm/kasan_def.h | 51 ++++++++++++++++++++++++++++++++++++++++
arch/arm/include/asm/memory.h | 5 ++++
arch/arm/kernel/entry-armv.S | 7 +++++-
3 files changed, 62 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/include/asm/kasan_def.h
diff --git a/arch/arm/include/asm/kasan_def.h b/arch/arm/include/asm/kasan_def.h
new file mode 100644
index 0000000..7746908
--- /dev/null
+++ b/arch/arm/include/asm/kasan_def.h
@@ -0,0 +1,51 @@
+#ifndef __ASM_KASAN_DEF_H
+#define __ASM_KASAN_DEF_H
+
+#ifdef CONFIG_KASAN
+
+/*
+ * +----+ 0xffffffff
+ * | |
+ * | |
+ * | |
+ * +----+ CONFIG_PAGE_OFFSET
+ * | |\
+ * | | |-> module virtual address space area.
+ * | |/
+ * +----+ MODULE_VADDR = KASAN_SHADOW_END
+ * | |\
+ * | | |-> the shadow area of kernel virtual address.
+ * | |/
+ * +----+ TASK_SIZE(start of kernel space) = KASAN_SHADOW_START the shadow address of MODULE_VADDR
+ * | |\
+ * | | ---------------------+
+ * | | |
+ * + + KASAN_SHADOW_OFFSET |-> the user space area. Kernel address sanitizer do not use this space.
+ * | | |
+ * | | ---------------------+
+ * | |/
+ * ------ 0
+ *
+ *1)KASAN_SHADOW_OFFSET:
+ * This value is used to map an address to the corresponding shadow address by the
+ * following formula:
+ * shadow_addr = (address >> 3) + KASAN_SHADOW_OFFSET;
+ *
+ * 2)KASAN_SHADOW_START
+ * This value is the MODULE_VADDR's shadow address. It is the start of kernel virtual
+ * space.
+ *
+ * 3) KASAN_SHADOW_END
+ * This value is the 0x100000000's shadow address. It is the end of kernel address
+ * sanitizer's shadow area. It is also the start of the module area.
+ *
+ */
+
+#define KASAN_SHADOW_OFFSET (KASAN_SHADOW_END - (1<<29))
+
+#define KASAN_SHADOW_START ((KASAN_SHADOW_END >> 3) + KASAN_SHADOW_OFFSET)
+
+#define KASAN_SHADOW_END (UL(CONFIG_PAGE_OFFSET) - UL(SZ_16M))
+
+#endif
+#endif
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 1f54e4e..069710d 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -21,6 +21,7 @@
#ifdef CONFIG_NEED_MACH_MEMORY_H
#include <mach/memory.h>
#endif
+#include <asm/kasan_def.h>
/*
* Allow for constants defined here to be used from assembly code
@@ -37,7 +38,11 @@
* TASK_SIZE - the maximum size of a user space task.
* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area
*/
+#ifndef CONFIG_KASAN
#define TASK_SIZE (UL(CONFIG_PAGE_OFFSET) - UL(SZ_16M))
+#else
+#define TASK_SIZE (KASAN_SHADOW_START)
+#endif
#define TASK_UNMAPPED_BASE ALIGN(TASK_SIZE / 3, SZ_16M)
/*
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index fbc7076..f9efea3 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -187,7 +187,12 @@ ENDPROC(__und_invalid)
get_thread_info tsk
ldr r0, [tsk, #TI_ADDR_LIMIT]
- mov r1, #TASK_SIZE
+#ifdef CONFIG_KASAN
+ movw r1, #:lower16:TASK_SIZE
+ movt r1, #:upper16:TASK_SIZE
+#else
+ mov r1, #TASK_SIZE
+#endif
str r1, [tsk, #TI_ADDR_LIMIT]
str r0, [sp, #SVC_ADDR_LIMIT]
--
2.9.0
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