aarch64: discard async aborts on entering debug state

recommended for Corte-A8 cores, not sure if necessary
for ARMv8 based cores as well.

Change-Id: Ibcb36170c5fac6a6b132de17f734c70a56919f9b
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>

src/target/aarch64.c

@@ -663,11 +663,16 @@ static int aarch64_debug_entry(struct target *target)
 	/* make sure to clear all sticky errors */
 	retval = mem_ap_write_atomic_u32(armv8->debug_ap,
 			armv8->debug_base + CPUV8_DBG_DRCR, DRCR_CSE);
+
+	/* discard async exceptions */
+	if (retval == ERROR_OK)
+		retval = dpm->instr_cpsr_sync(dpm);
+
 	if (retval != ERROR_OK)
 		return retval;
 
 	/* Examine debug reason */
-	armv8_dpm_report_dscr(&armv8->dpm, aarch64->cpudbg_dscr);
+	armv8_dpm_report_dscr(dpm, aarch64->cpudbg_dscr);
 
 	/* save address of instruction that triggered the watchpoint? */
 	if (target->debug_reason == DBG_REASON_WATCHPOINT) {

src/target/armv8_dpm.c

@@ -360,9 +360,14 @@ static int dpmv8_instr_write_data_r0_64(struct arm_dpm *dpm,
 
 static int dpmv8_instr_cpsr_sync(struct arm_dpm *dpm)
 {
+	int retval;
 	struct armv8_common *armv8 = dpm->arm->arch_info;
+
 	/* "Prefetch flush" after modifying execution status in CPSR */
-	return dpmv8_exec_opcode(dpm, armv8_opcode(armv8, ARMV8_OPC_DSB_SY), NULL);
+	retval = dpmv8_exec_opcode(dpm, armv8_opcode(armv8, ARMV8_OPC_DSB_SY), &dpm->dscr);
+	if (retval == ERROR_OK)
+		dpmv8_exec_opcode(dpm, armv8_opcode(armv8, ARMV8_OPC_ISB_SY), &dpm->dscr);
+	return retval;
 }
 
 static int dpmv8_instr_read_data_dcc(struct arm_dpm *dpm,

src/target/armv8_opcodes.c

@@ -37,6 +37,7 @@ static const uint32_t a64_opcodes[ARMV8_OPC_NUM] = {
 		[ARMV8_OPC_DSB_SY]	= ARMV8_DSB_SY,
 		[ARMV8_OPC_DCPS]	= ARMV8_DCPS(0, 11),
 		[ARMV8_OPC_DRPS]	= ARMV8_DRPS,
+		[ARMV8_OPC_ISB_SY]	= ARMV8_ISB,
 };
 
 static const uint32_t t32_opcodes[ARMV8_OPC_NUM] = {
@@ -53,6 +54,7 @@ static const uint32_t t32_opcodes[ARMV8_OPC_NUM] = {
 		[ARMV8_OPC_DSB_SY]	= ARMV8_DSB_SY_T1,
 		[ARMV8_OPC_DCPS]	= ARMV8_DCPS_T1(0),
 		[ARMV8_OPC_DRPS]	= ARMV8_ERET_T1,
+		[ARMV8_OPC_ISB_SY]	= ARMV8_ISB_SY_T1,
 };
 
 void armv8_select_opcodes(struct armv8_common *armv8, bool state_is_aarch64)

src/target/armv8_opcodes.h

@@ -135,6 +135,8 @@
 
 #define ARMV8_DSB_SY				0xd5033F9F
 #define ARMV8_DSB_SY_T1				0xf3bf8f4f
+#define ARMV8_ISB				0xd5033fdf
+#define ARMV8_ISB_SY_T1				0xf3bf8f6f
 
 #define ARMV8_MRS(System, Rt)	(0xd5300000 | ((System) << 5) | (Rt))
 /* ARM V8 Move to system register. */
@@ -173,6 +175,7 @@ enum armv8_opcode {
 	ARMV8_OPC_DSB_SY,
 	ARMV8_OPC_DCPS,
 	ARMV8_OPC_DRPS,
+	ARMV8_OPC_ISB_SY,
 	ARMV8_OPC_NUM,
 };