/* * arch/xtensa/kernel/stacktrace.c * * This file is subject to the terms and conditions of the GNU General Public * License.  See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 2001 - 2013 Tensilica Inc. */#include <linux/export.h>#include <linux/sched.h>#include <linux/stacktrace.h> #include <asm/stacktrace.h>#include <asm/traps.h> void walk_stackframe(unsigned long *sp,		int (*fn)(struct stackframe *frame, void *data),		void *data){	unsigned long a0, a1;	unsigned long sp_end; 	a1 = (unsigned long)sp;	sp_end = ALIGN(a1, THREAD_SIZE); 	spill_registers(); 	while (a1 < sp_end) {		struct stackframe frame; 		sp = (unsigned long *)a1; 		a0 = *(sp - 4);		a1 = *(sp - 3); 		if (a1 <= (unsigned long)sp)			break; 		frame.pc = MAKE_PC_FROM_RA(a0, a1);		frame.sp = a1; 		if (fn(&frame, data))			return;	}} #ifdef CONFIG_STACKTRACE struct stack_trace_data {	struct stack_trace *trace;	unsigned skip;}; static int stack_trace_cb(struct stackframe *frame, void *data){	struct stack_trace_data *trace_data = data;	struct stack_trace *trace = trace_data->trace; 	if (trace_data->skip) {		--trace_data->skip;		return 0;	}	if (!kernel_text_address(frame->pc))		return 0; 	trace->entries[trace->nr_entries++] = frame->pc;	return trace->nr_entries >= trace->max_entries;} void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace){	struct stack_trace_data trace_data = {		.trace = trace,		.skip = trace->skip,	};	walk_stackframe(stack_pointer(task), stack_trace_cb, &trace_data);}EXPORT_SYMBOL_GPL(save_stack_trace_tsk); void save_stack_trace(struct stack_trace *trace){	save_stack_trace_tsk(current, trace);}EXPORT_SYMBOL_GPL(save_stack_trace); #endif #ifdef CONFIG_FRAME_POINTER struct return_addr_data {	unsigned long addr;	unsigned skip;}; static int return_address_cb(struct stackframe *frame, void *data){	struct return_addr_data *r = data; 	if (r->skip) {		--r->skip;		return 0;	}	if (!kernel_text_address(frame->pc))		return 0;	r->addr = frame->pc;	return 1;} unsigned long return_address(unsigned level){	struct return_addr_data r = {		.skip = level + 1,	};	walk_stackframe(stack_pointer(NULL), return_address_cb, &r);	return r.addr;}EXPORT_SYMBOL(return_address); #endif