[v12,11/12] arm64: scs: add shadow stacks for SDEI
diff mbox series

Message ID 20200421021453.198187-12-samitolvanen@google.com
State New
Headers show
Series
  • add support for Clang's Shadow Call Stack
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Commit Message

Sami Tolvanen April 21, 2020, 2:14 a.m. UTC
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: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: James Morse <james.morse@arm.com>
Tested-by: James Morse <james.morse@arm.com>
---
 arch/arm64/kernel/entry.S | 14 +++++++++++++-
 arch/arm64/kernel/scs.c   |  5 +++++
 2 files changed, 18 insertions(+), 1 deletion(-)

Patch
diff mbox series

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 14f0ff763b39..9f7be489d26d 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1058,13 +1058,16 @@  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
@@ -1074,6 +1077,15 @@  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.
diff --git a/arch/arm64/kernel/scs.c b/arch/arm64/kernel/scs.c
index 086ad97bba86..656262736eca 100644
--- a/arch/arm64/kernel/scs.c
+++ b/arch/arm64/kernel/scs.c
@@ -14,3 +14,8 @@ 
 		__aligned(SCS_SIZE)
 
 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