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 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(VERIFY_READ, 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