Commit f8a3930d authored Oct 03, 2017 by Mark Rutland Committed by Prasad Sodagudi Nov 20, 2017

arm64: Use larger stacks when KASAN is selected



AddressSanitizer instrumentation can significantly bloat the stack, and
with GCC 7 this can result in stack overflows at boot time in some
configurations.

We can avoid this by doubling our stack size when KASAN is in use, as is
already done on x86 (and has been since KASAN was introduced).
Regardless of other patches to decrease KASAN's stack utilization,
kernels built with KASAN will always require more stack space than those
built without, and we should take this into account.

Change-Id: I3da9bea59c6f3580bfe15d1b2d1f2a208a9a0401
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: b02faed15d86f846b0f23f47b92e0782baa873ed
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>

parent 69100f67

arch/arm64/include/asm/memory.h

+6 −3

Original line number	Diff line number	Diff line
		@@ -93,16 +93,19 @@
		#define KERNEL_END _end

		/*
		* The size of the KASAN shadow region. This should be 1/8th of the
		* size of the entire kernel virtual address space.
		* KASAN requires 1/8th of the kernel virtual address space for the shadow
		* region. KASAN can bloat the stack significantly, so double the (minimum)
		* stack size when KASAN is in use.
		*/
		#ifdef CONFIG_KASAN
		#define KASAN_SHADOW_SIZE (UL(1) << (VA_BITS - 3))
		#define KASAN_THREAD_SHIFT 1
		#else
		#define KASAN_SHADOW_SIZE (0)
		#define KASAN_THREAD_SHIFT 0
		#endif

		#define THREAD_SHIFT 14
		#define THREAD_SHIFT (14 + KASAN_THREAD_SHIFT)

		#if THREAD_SHIFT >= PAGE_SHIFT
		#define THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT)