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Commit 1eb12882 authored by Sami Tolvanen's avatar Sami Tolvanen
Browse files

ANDROID: scs: use vmapped shadow stacks by default 



Enable CONFIG_SHADOW_CALL_STACK_VMAP by default, and as we allocate
a full page for the stack, allow the kernel use all of it.

Bug: 169781940
Change-Id: Ie8eaa7f24e9bf10ff28a302ac98ad843b71c9c2a
Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
parent b494bbca

arch/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -549,6 +549,7 @@ config SHADOW_CALL_STACK 
config SHADOW_CALL_STACK_VMAP

	bool "Use virtually mapped shadow call stacks"

	depends on SHADOW_CALL_STACK

	default y

	help

	  Use virtually mapped shadow call stacks. Selecting this option

	  provides better stack exhaustion protection, but increases per-thread

include/linux/scs.h

+5 −0
Original line number Diff line number Diff line
@@ -14,12 +14,17 @@ 


#ifdef CONFIG_SHADOW_CALL_STACK



#ifdef CONFIG_SHADOW_CALL_STACK_VMAP

#define SCS_SIZE	PAGE_SIZE

#else

/*

 * In testing, 1 KiB shadow stack size (i.e. 128 stack frames on a 64-bit

 * architecture) provided ~40% safety margin on stack usage while keeping

 * memory allocation overhead reasonable.

 */

#define SCS_SIZE	1024UL

#endif



#define GFP_SCS		(GFP_KERNEL | __GFP_ZERO)



/*