rtos/zephyr: arc: fetch the relinquish cause

If a thread is preempted in an interrupt, we can read the caller-saved registers from its stack.

Signed-off-by: Bruno Mendes <bd_mendes@outlook.com>

src/rtos/zephyr.c

@@ -29,6 +29,10 @@
 /* ARC specific defines */
 #define ARC_AUX_SEC_BUILD_REG 0xdb
 #define ARC_REG_NUM 38
+#define ARC_RELINQUISH_CAUSE_NONE 0
+#define ARC_RELINQUISH_CAUSE_COOP 1
+#define ARC_RELINQUISH_CAUSE_RIRQ 2
+#define ARC_RELINQUISH_CAUSE_FIRQ 3
 
 /* ARM specific defines */
 #define ARM_XPSR_OFFSET 28
@@ -57,6 +61,8 @@ enum zephyr_offsets {
 	OFFSET_T_ARCH,
 	OFFSET_T_PREEMPT_FLOAT,
 	OFFSET_T_COOP_FLOAT,
+	OFFSET_T_ARM_EXC_RETURN,
+	OFFSET_T_ARC_RELINQUISH_CAUSE,
 	OFFSET_MAX
 };
 
@@ -228,7 +234,6 @@ static struct stack_register_offset arc_cpu_saved_preempt[] = {
 	{ ARC_STATUS32,		 4,  32 }
 };
 
-
 enum zephyr_symbol_values {
 	ZEPHYR_VAL__KERNEL,
 	ZEPHYR_VAL__KERNEL_OPENOCD_OFFSETS,
@@ -299,8 +304,8 @@ static int zephyr_get_arc_state(struct rtos *rtos, target_addr_t *addr,
 	if (retval != ERROR_OK)
 		return retval;
 
-	/* TODO check relinquish state and opt for coop or preempt */
-	stacking = params->cpu_saved_nofp_stacking_coop;
+	stacking = params->offsets[OFFSET_T_ARC_RELINQUISH_CAUSE] == ARC_RELINQUISH_CAUSE_RIRQ || ARC_RELINQUISH_CAUSE_FIRQ ?
+		params->cpu_saved_nofp_stacking_preempt : params->cpu_saved_nofp_stacking_coop;
 
 	/* Getting cpu saved registers into reg_list */
 	retval = rtos_generic_stack_read(rtos->target, stacking,
@@ -368,14 +373,9 @@ static int zephyr_get_arm_state(struct rtos *rtos, target_addr_t *addr,
 			callee_saved_reg_list[0].value);
 
 	if (params->offsets[OFFSET_T_PREEMPT_FLOAT] != UNIMPLEMENTED)
-	{
 		stacking = params->cpu_saved_fp_stacking;
-	}
-	else
-	{
-		/* TODO check relinquish state and opt for coop or preempt */
+	else 
 		stacking = params->cpu_saved_nofp_stacking_coop;
-	}
 
 	retval = rtos_generic_stack_read(rtos->target, stacking, *addr, reg_list,
 			num_regs);
@@ -714,6 +714,7 @@ static int zephyr_update_threads(struct rtos *rtos)
 	}
 
 	if (rtos->symbols[ZEPHYR_VAL__KERNEL_OPENOCD_NUM_OFFSETS].address) {
+		/* use the number of offsets symbol issued by the kernel */
 		retval = target_read_u32(rtos->target,
 				rtos->symbols[ZEPHYR_VAL__KERNEL_OPENOCD_NUM_OFFSETS].address,
 				&param->num_offsets);
@@ -727,6 +728,7 @@ static int zephyr_update_threads(struct rtos *rtos)
 			return ERROR_FAIL;
 		}
 	} else {
+		/* hardcode the number of offsets based on the offsets version */
 		retval = target_read_u32(rtos->target,
 				rtos->symbols[ZEPHYR_VAL__KERNEL_OPENOCD_OFFSETS].address,
 				&param->offsets[OFFSET_VERSION]);
@@ -740,6 +742,7 @@ static int zephyr_update_threads(struct rtos *rtos)
 					param->offsets[OFFSET_VERSION]);
 			return ERROR_FAIL;
 		}
+
 		switch (param->offsets[OFFSET_VERSION]) {
 		case 0:
 			param->num_offsets = OFFSET_T_STACK_POINTER + 1;
@@ -749,6 +752,7 @@ static int zephyr_update_threads(struct rtos *rtos)
 			break;
 		}
 	}
+
 	/* We can fetch the whole array for version 0, as they're supposed
 	 * to grow only */
 	uint32_t address;