xtensa: fix getting exccause during backtrace

We have frame pointer struct and BSA struct to extract
the exception cause (exccause). There is no need to
resort to custom assembly to do that. Besides, given
that the BSA is different between different Xtensa cores,
there is no guarantee it is at the same place as what
the assembly assumes. So just do that without assembly.

Signed-off-by: Daniel Leung <[email protected]>

Author: dcpleung

arch/xtensa/core/xtensa_backtrace.c

@@ -14,6 +14,9 @@
 #elif defined(CONFIG_SOC_XTENSA_DC233C)
 #include "backtrace_helpers.h"
 #endif
+
+#include <xtensa_asm2_context.h>
+
 static int mask, cause;
 
 static inline uint32_t xtensa_cpu_process_stack_pc(uint32_t pc)
@@ -91,14 +94,18 @@ int xtensa_backtrace_print(int depth, int *interrupted_stack)
 		return -1;
 	}
 
+	_xtensa_irq_stack_frame_raw_t *frame = (void *)interrupted_stack;
+	_xtensa_irq_bsa_t *bsa;
+
+	bsa = frame->ptr_to_bsa;
+	cause = bsa->exccause;
+
 	/* Initialize stk_frame with first frame of stack */
 	struct xtensa_backtrace_frame_t stk_frame;
 
 	xtensa_backtrace_get_start(&(stk_frame.pc), &(stk_frame.sp),
 			&(stk_frame.next_pc), interrupted_stack);
-	__asm__ volatile("l32i a4, a3, 0");
-	__asm__ volatile("l32i a4, a4, 4");
-	__asm__ volatile("mov %0, a4" : "=r"(cause));
+
 	if (cause != EXCCAUSE_INSTR_PROHIBITED) {
 		mask = stk_frame.pc & 0xc0000000;
 	}