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/*
* AVR32 specific backtracing code for oprofile
*
* Copyright 2008 Weinmann GmbH
*
* Author: Nikolaus Voss <n.voss@weinmann.de>
*
* Based on i386 oprofile backtrace code by John Levon and 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/uaccess.h>
/* The first two words of each frame on the stack look like this if we have
* frame pointers */
struct frame_head {
unsigned long lr;
struct frame_head *fp;
};
/* copied from arch/avr32/kernel/process.c */
static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p)
{
return (p > (unsigned long)tinfo)
&& (p < (unsigned long)tinfo + THREAD_SIZE - 3);
}
/* copied from arch/x86/oprofile/backtrace.c */
static struct frame_head *dump_user_backtrace(struct frame_head *head)
{
struct frame_head bufhead[2];
/* Also check accessibility of one struct frame_head beyond */
if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
return NULL;
if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
return NULL;
oprofile_add_trace(bufhead[0].lr);
/* frame pointers should strictly progress back up the stack
* (towards higher addresses) */
if (bufhead[0].fp <= head)
return NULL;
return bufhead[0].fp;
}
void avr32_backtrace(struct pt_regs * const regs, unsigned int depth)
{
/* Get first frame pointer */
struct frame_head *head = (struct frame_head *)(regs->r7);
if (!user_mode(regs)) {
#ifdef CONFIG_FRAME_POINTER
/*
* Traverse the kernel stack from frame to frame up to
* "depth" steps.
*/
while (depth-- && valid_stack_ptr(task_thread_info(current),
(unsigned long)head)) {
oprofile_add_trace(head->lr);
if (head->fp <= head)
break;
head = head->fp;
}
#endif
} else {
/* Assume we have frame pointers in user mode process */
while (depth-- && head)
head = dump_user_backtrace(head);
}
}
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