/* * Stack trace utility * * Copyright 2008 Christoph Hellwig, IBM Corp. * * *      This program is free software; you can redistribute it and/or *      modify it under the terms of the GNU General Public License *      as published by the Free Software Foundation; either version *      2 of the License, or (at your option) any later version. */ #include <linux/export.h>#include <linux/sched.h>#include <linux/sched/debug.h>#include <linux/stacktrace.h>#include <asm/ptrace.h>#include <asm/processor.h> /* * Save stack-backtrace addresses into a stack_trace buffer. */static void save_context_stack(struct stack_trace *trace, unsigned long sp,			struct task_struct *tsk, int savesched){	for (;;) {		unsigned long *stack = (unsigned long *) sp;		unsigned long newsp, ip; 		if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))			return; 		newsp = stack[0];		ip = stack[STACK_FRAME_LR_SAVE]; 		if (savesched || !in_sched_functions(ip)) {			if (!trace->skip)				trace->entries[trace->nr_entries++] = ip;			else				trace->skip--;		} 		if (trace->nr_entries >= trace->max_entries)			return; 		sp = newsp;	}} void save_stack_trace(struct stack_trace *trace){	unsigned long sp; 	sp = current_stack_pointer(); 	save_context_stack(trace, sp, current, 1);}EXPORT_SYMBOL_GPL(save_stack_trace); void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace){	unsigned long sp; 	if (tsk == current)		sp = current_stack_pointer();	else		sp = tsk->thread.ksp; 	save_context_stack(trace, sp, tsk, 0);}EXPORT_SYMBOL_GPL(save_stack_trace_tsk); voidsave_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace){	save_context_stack(trace, regs->gpr[1], current, 0);}EXPORT_SYMBOL_GPL(save_stack_trace_regs);