LXR linux/arch/avr32/oprofile/backtrace.c

   1/*
   2 * AVR32 specific backtracing code for oprofile
   3 *
   4 * Copyright 2008 Weinmann GmbH
   5 *
   6 * Author: Nikolaus Voss <n.voss@weinmann.de>
   7 *
   8 * Based on i386 oprofile backtrace code by John Levon and David Smith
   9 *
  10 * This program is free software; you can redistribute it and/or modify
  11 * it under the terms of the GNU General Public License version 2 as
  12 * published by the Free Software Foundation.
  13 *
  14 */
  15
  16#include <linux/oprofile.h>
  17#include <linux/sched.h>
  18#include <linux/uaccess.h>
  19
  20/* The first two words of each frame on the stack look like this if we have
  21 * frame pointers */
  22struct frame_head {
  23        unsigned long lr;
  24        struct frame_head *fp;
  25};
  26
  27/* copied from arch/avr32/kernel/process.c */
  28static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p)
  29{
  30        return (p > (unsigned long)tinfo)
  31                && (p < (unsigned long)tinfo + THREAD_SIZE - 3);
  32}
  33
  34/* copied from arch/x86/oprofile/backtrace.c */
  35static struct frame_head *dump_user_backtrace(struct frame_head *head)
  36{
  37        struct frame_head bufhead[2];
  38
  39        /* Also check accessibility of one struct frame_head beyond */
  40        if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
  41                return NULL;
  42        if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
  43                return NULL;
  44
  45        oprofile_add_trace(bufhead[0].lr);
  46
  47        /* frame pointers should strictly progress back up the stack
  48         * (towards higher addresses) */
  49        if (bufhead[0].fp <= head)
  50                return NULL;
  51
  52        return bufhead[0].fp;
  53}
  54
  55void avr32_backtrace(struct pt_regs * const regs, unsigned int depth)
  56{
  57        /* Get first frame pointer */
  58        struct frame_head *head = (struct frame_head *)(regs->r7);
  59
  60        if (!user_mode(regs)) {
  61#ifdef CONFIG_FRAME_POINTER
  62                /*
  63                 * Traverse the kernel stack from frame to frame up to
  64                 * "depth" steps.
  65                 */
  66                while (depth-- && valid_stack_ptr(task_thread_info(current),
  67                                                  (unsigned long)head)) {
  68                        oprofile_add_trace(head->lr);
  69                        if (head->fp <= head)
  70                                break;
  71                        head = head->fp;
  72                }
  73#endif
  74        } else {
  75                /* Assume we have frame pointers in user mode process */
  76                while (depth-- && head)
  77                        head = dump_user_backtrace(head);
  78        }
  79}
  80
  81
  82