Commit 439dc2a1 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Will Deacon
Browse files

arm64: scs: Add shadow stacks for SDEI 



This change adds per-CPU shadow call stacks for the SDEI handler.
Similarly to how the kernel stacks are handled, we add separate shadow
stacks for normal and critical events.

Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Tested-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 5287569a

arch/arm64/kernel/entry.S

+13 −1
Original line number Diff line number Diff line
@@ -1049,13 +1049,16 @@ SYM_CODE_START(__sdei_asm_handler) 


	mov	x19, x1



#if defined(CONFIG_VMAP_STACK) || defined(CONFIG_SHADOW_CALL_STACK)

	ldrb	w4, [x19, #SDEI_EVENT_PRIORITY]

#endif



#ifdef CONFIG_VMAP_STACK

	/*

	 * entry.S may have been using sp as a scratch register, find whether

	 * this is a normal or critical event and switch to the appropriate

	 * stack for this CPU.

	 */

	ldrb	w4, [x19, #SDEI_EVENT_PRIORITY]

	cbnz	w4, 1f

	ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6

	b	2f
@@ -1065,6 +1068,15 @@ SYM_CODE_START(__sdei_asm_handler) 
	mov	sp, x5

#endif



#ifdef CONFIG_SHADOW_CALL_STACK

	/* Use a separate shadow call stack for normal and critical events */

	cbnz	w4, 3f

	adr_this_cpu dst=x18, sym=sdei_shadow_call_stack_normal, tmp=x6

	b	4f

3:	adr_this_cpu dst=x18, sym=sdei_shadow_call_stack_critical, tmp=x6

4:

#endif



	/*

	 * We may have interrupted userspace, or a guest, or exit-from or

	 * return-to either of these. We can't trust sp_el0, restore it.

arch/arm64/kernel/scs.c

+5 −0
Original line number Diff line number Diff line
@@ -13,3 +13,8 @@ 
	DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name)	\



DEFINE_SCS(irq_shadow_call_stack);



#ifdef CONFIG_ARM_SDE_INTERFACE

DEFINE_SCS(sdei_shadow_call_stack_normal);

DEFINE_SCS(sdei_shadow_call_stack_critical);

#endif