/*
   * SH specific backtracing code for oprofile
   *
   * Copyright 2007 STMicroelectronics Ltd.
   *
   * Author: Dave Peverley <dpeverley@mpc-data.co.uk>
   *
   * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
   * oprofile backtrace code by John Levon, David Smith
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   */
  #include <linux/oprofile.h>
  #include <linux/sched.h>
  #include <linux/kallsyms.h>
  #include <linux/mm.h>

  #include <asm/unwinder.h>

  #include <asm/ptrace.h>
  #include <asm/uaccess.h>
  #include <asm/sections.h>

  #include <asm/stacktrace.h>

  static int backtrace_stack(void *data, char *name)
  {
  	/* Yes, we want all stacks */
  	return 0;
  }
  
  static void backtrace_address(void *data, unsigned long addr, int reliable)
  {
  	unsigned int *depth = data;
  
  	if ((*depth)--)
  		oprofile_add_trace(addr);
  }
  
  static struct stacktrace_ops backtrace_ops = {

  	.stack = backtrace_stack,
  	.address = backtrace_address,
  };

  
  /* Limit to stop backtracing too far. */
  static int backtrace_limit = 20;
  
  static unsigned long *
  user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
  {
  	unsigned long buf_stack;
  
  	/* Also check accessibility of address */
  	if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
  		return NULL;
  
  	if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
  		return NULL;
  
  	/* Quick paranoia check */
  	if (buf_stack & 3)
  		return NULL;
  
  	oprofile_add_trace(buf_stack);
  
  	stackaddr++;
  
  	return stackaddr;
  }

  void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
  {
  	unsigned long *stackaddr;
  
  	/*
  	 * Paranoia - clip max depth as we could get lost in the weeds.
  	 */
  	if (depth > backtrace_limit)
  		depth = backtrace_limit;

  	stackaddr = (unsigned long *)kernel_stack_pointer(regs);

  	if (!user_mode(regs)) {

  		if (depth)

  			unwind_stack(NULL, regs, stackaddr,
  				     &backtrace_ops, &depth);

  		return;
  	}
  
  	while (depth-- && (stackaddr != NULL))
  		stackaddr = user_backtrace(stackaddr, regs);
  }