From 39d114ddc68223022c12ae3a1573912bc4b585e5 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Mon, 12 Oct 2015 18:52:58 +0300 Subject: arm64: add KASAN support This patch adds arch specific code for kernel address sanitizer (see Documentation/kasan.txt). 1/8 of kernel addresses reserved for shadow memory. There was no big enough hole for this, so virtual addresses for shadow were stolen from vmalloc area. At early boot stage the whole shadow region populated with just one physical page (kasan_zero_page). Later, this page reused as readonly zero shadow for some memory that KASan currently don't track (vmalloc). After mapping the physical memory, pages for shadow memory are allocated and mapped. Functions like memset/memmove/memcpy do a lot of memory accesses. If bad pointer passed to one of these function it is important to catch this. Compiler's instrumentation cannot do this since these functions are written in assembly. KASan replaces memory functions with manually instrumented variants. Original functions declared as weak symbols so strong definitions in mm/kasan/kasan.c could replace them. Original functions have aliases with '__' prefix in name, so we could call non-instrumented variant if needed. Some files built without kasan instrumentation (e.g. mm/slub.c). Original mem* function replaced (via #define) with prefixed variants to disable memory access checks for such files. Signed-off-by: Andrey Ryabinin Tested-by: Linus Walleij Reviewed-by: Catalin Marinas Signed-off-by: Catalin Marinas --- scripts/Makefile.kasan | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'scripts/Makefile.kasan') diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan index 3f874d24234f..37323b0df374 100644 --- a/scripts/Makefile.kasan +++ b/scripts/Makefile.kasan @@ -5,10 +5,12 @@ else call_threshold := 0 endif +KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET) + CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \ - -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \ + -fasan-shadow-offset=$(KASAN_SHADOW_OFFSET) \ --param asan-stack=1 --param asan-globals=1 \ --param asan-instrumentation-with-call-threshold=$(call_threshold)) -- cgit v1.2.3-70-g09d2