From 3b735c8fec750a9074b0e4c602a43bc5ecebb56a Mon Sep 17 00:00:00 2001
From: Bin Lu <bin.lu@arm.com>
Date: Thu, 15 Oct 2020 22:34:39 -0400
Subject: arm64 kvm: handle exception from accessing undefined instruction

Consistent with the linux approach, we will produce a sigill to handle
el0_undef.

After applying this patch, exec_binary_test_runsc_kvm will be passed on
Arm64.

Signed-off-by: Bin Lu <bin.lu@arm.com>
---
 pkg/sentry/platform/kvm/machine_arm64_unsafe.go |  5 ++--
 pkg/sentry/platform/ring0/entry_arm64.s         | 34 +++++++++++--------------
 2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/pkg/sentry/platform/kvm/machine_arm64_unsafe.go b/pkg/sentry/platform/kvm/machine_arm64_unsafe.go
index a163f956d..84992c06d 100644
--- a/pkg/sentry/platform/kvm/machine_arm64_unsafe.go
+++ b/pkg/sentry/platform/kvm/machine_arm64_unsafe.go
@@ -235,8 +235,9 @@ func (c *vCPU) SwitchToUser(switchOpts ring0.SwitchOpts, info *arch.SignalInfo)
 		return c.fault(int32(syscall.SIGSEGV), info)
 	case ring0.Vector(bounce): // ring0.VirtualizationException
 		return usermem.NoAccess, platform.ErrContextInterrupt
-	case ring0.El0Sync_undef,
-		ring0.El1Sync_undef:
+	case ring0.El0Sync_undef:
+		return c.fault(int32(syscall.SIGILL), info)
+	case ring0.El1Sync_undef:
 		*info = arch.SignalInfo{
 			Signo: int32(syscall.SIGILL),
 			Code:  1, // ILL_ILLOPC (illegal opcode).
diff --git a/pkg/sentry/platform/ring0/entry_arm64.s b/pkg/sentry/platform/ring0/entry_arm64.s
index 2370a9276..1079a024b 100644
--- a/pkg/sentry/platform/ring0/entry_arm64.s
+++ b/pkg/sentry/platform/ring0/entry_arm64.s
@@ -366,6 +366,19 @@
 	MOVD R4, CPU_REGISTERS+PTRACE_SP(RSV_REG); \
 	LOAD_KERNEL_STACK(RSV_REG);  // Load the temporary stack.
 
+// EXCEPTION_WITH_ERROR is a common exception handler function.
+#define EXCEPTION_WITH_ERROR(user, vector) \
+	WORD $0xd538d092; \	//MRS   TPIDR_EL1, R18
+	WORD $0xd538601a; \	//MRS   FAR_EL1, R26
+	MOVD R26, CPU_FAULT_ADDR(RSV_REG); \
+	MOVD $user, R3; \
+	MOVD R3, CPU_ERROR_TYPE(RSV_REG); \	// Set error type to user.
+	MOVD $vector, R3; \
+	MOVD R3, CPU_VECTOR_CODE(RSV_REG); \
+	MRS ESR_EL1, R3; \
+	MOVD R3, CPU_ERROR_CODE(RSV_REG); \
+	B ·kernelExitToEl1(SB);
+
 // storeAppASID writes the application's asid value.
 TEXT ·storeAppASID(SB),NOSPLIT,$0-8
 	MOVD asid+0(FP), R1
@@ -659,21 +672,7 @@ el0_svc:
 
 el0_da:
 el0_ia:
-	WORD $0xd538d092     //MRS   TPIDR_EL1, R18
-	WORD $0xd538601a     //MRS   FAR_EL1, R26
-
-	MOVD R26, CPU_FAULT_ADDR(RSV_REG)
-
-	MOVD $1, R3
-	MOVD R3, CPU_ERROR_TYPE(RSV_REG) // Set error type to user.
-
-	MOVD $PageFault, R3
-	MOVD R3, CPU_VECTOR_CODE(RSV_REG)
-
-	MRS ESR_EL1, R3
-	MOVD R3, CPU_ERROR_CODE(RSV_REG)
-
-	B ·kernelExitToEl1(SB)
+	EXCEPTION_WITH_ERROR(1, PageFault)
 
 el0_fpsimd_acc:
 	B ·Shutdown(SB)
@@ -688,10 +687,7 @@ el0_sp_pc:
 	B ·Shutdown(SB)
 
 el0_undef:
-	MOVD $El0Sync_undef, R3
-	MOVD R3, CPU_VECTOR_CODE(RSV_REG)
-
-	B ·kernelExitToEl1(SB)
+	EXCEPTION_WITH_ERROR(1, El0Sync_undef)
 
 el0_dbg:
 	B ·Shutdown(SB)
-- 
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