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 <asm/uaccess.h>
  23#include <asm/sections.h>
  24#include <asm/stacktrace.h>
  25
  26static void backtrace_warning_symbol(void *data, char *msg,
  27                                     unsigned long symbol)
  28{
  29        /* Ignore warnings */
  30}
  31
  32static void backtrace_warning(void *data, char *msg)
  33{
  34        /* Ignore warnings */
  35}
  36
  37static int backtrace_stack(void *data, char *name)
  38{
  39        /* Yes, we want all stacks */
  40        return 0;
  41}
  42
  43static void backtrace_address(void *data, unsigned long addr, int reliable)
  44{
  45        unsigned int *depth = data;
  46
  47        if ((*depth)--)
  48                oprofile_add_trace(addr);
  49}
  50
  51static struct stacktrace_ops backtrace_ops = {
  52        .warning = backtrace_warning,
  53        .warning_symbol = backtrace_warning_symbol,
  54        .stack = backtrace_stack,
  55        .address = backtrace_address,
  56};
  57
  58/* Limit to stop backtracing too far. */
  59static int backtrace_limit = 20;
  60
  61static unsigned long *
  62user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
  63{
  64        unsigned long buf_stack;
  65
  66        /* Also check accessibility of address */
  67        if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
  68                return NULL;
  69
  70        if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
  71                return NULL;
  72
  73        /* Quick paranoia check */
  74        if (buf_stack & 3)
  75                return NULL;
  76
  77        oprofile_add_trace(buf_stack);
  78
  79        stackaddr++;
  80
  81        return stackaddr;
  82}
  83
  84void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
  85{
  86        unsigned long *stackaddr;
  87
  88        /*
  89         * Paranoia - clip max depth as we could get lost in the weeds.
  90         */
  91        if (depth > backtrace_limit)
  92                depth = backtrace_limit;
  93
  94        stackaddr = (unsigned long *)regs->regs[15];
  95        if (!user_mode(regs)) {
  96                if (depth)
  97                        unwind_stack(NULL, regs, stackaddr,
  98                                     &backtrace_ops, &depth);
  99                return;
 100        }
 101
 102        while (depth-- && (stackaddr != NULL))
 103                stackaddr = user_backtrace(stackaddr, regs);
 104}
 105