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

   1/*
   2 * SH specific backtracing code for oprofile
   3 *
   4 * Copyright 2007 STMicroelectronics Ltd.
   5 *
   6 * Author: Dave Peverley <dpeverley@mpc-data.co.uk>
   7 *
   8 * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
   9 * oprofile backtrace code by John Levon, David Smith
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License version 2 as
  13 * published by the Free Software Foundation.
  14 *
  15 */
  16#include <linux/oprofile.h>
  17#include <linux/sched.h>
  18#include <linux/kallsyms.h>
  19#include <linux/mm.h>
  20#include <asm/unwinder.h>
  21#include <asm/ptrace.h>
  22#include <linux/uaccess.h>
  23#include <asm/sections.h>
  24#include <asm/stacktrace.h>
  25
  26static int backtrace_stack(void *data, char *name)
  27{
  28        /* Yes, we want all stacks */
  29        return 0;
  30}
  31
  32static void backtrace_address(void *data, unsigned long addr, int reliable)
  33{
  34        unsigned int *depth = data;
  35
  36        if ((*depth)--)
  37                oprofile_add_trace(addr);
  38}
  39
  40static struct stacktrace_ops backtrace_ops = {
  41        .stack = backtrace_stack,
  42        .address = backtrace_address,
  43};
  44
  45/* Limit to stop backtracing too far. */
  46static int backtrace_limit = 20;
  47
  48static unsigned long *
  49user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
  50{
  51        unsigned long buf_stack;
  52
  53        /* Also check accessibility of address */
  54        if (!access_ok(stackaddr, sizeof(unsigned long)))
  55                return NULL;
  56
  57        if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
  58                return NULL;
  59
  60        /* Quick paranoia check */
  61        if (buf_stack & 3)
  62                return NULL;
  63
  64        oprofile_add_trace(buf_stack);
  65
  66        stackaddr++;
  67
  68        return stackaddr;
  69}
  70
  71void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
  72{
  73        unsigned long *stackaddr;
  74
  75        /*
  76         * Paranoia - clip max depth as we could get lost in the weeds.
  77         */
  78        if (depth > backtrace_limit)
  79                depth = backtrace_limit;
  80
  81        stackaddr = (unsigned long *)kernel_stack_pointer(regs);
  82        if (!user_mode(regs)) {
  83                if (depth)
  84                        unwind_stack(NULL, regs, stackaddr,
  85                                     &backtrace_ops, &depth);
  86                return;
  87        }
  88
  89        while (depth-- && (stackaddr != NULL))
  90                stackaddr = user_backtrace(stackaddr, regs);
  91}
  92