summaryrefslogtreecommitdiffstats
path: root/arch/sh/oprofile/backtrace.c
blob: 62e4e4d0273e26fda1d5e63aed9787a8a829029c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
/*
 * SH specific backtracing code for oprofile
 *
 * Copyright 2007 STMicroelectronics Ltd.
 *
 * Author: Dave Peverley <dpeverley@mpc-data.co.uk>
 *
 * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
 * oprofile backtrace code by John Levon, 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/kallsyms.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
#include <asm/sections.h>
#include <asm/stacktrace.h>

static void backtrace_warning_symbol(void *data, char *msg,
				     unsigned long symbol)
{
	/* Ignore warnings */
}

static void backtrace_warning(void *data, char *msg)
{
	/* Ignore warnings */
}

static int backtrace_stack(void *data, char *name)
{
	/* Yes, we want all stacks */
	return 0;
}

static void backtrace_address(void *data, unsigned long addr, int reliable)
{
	unsigned int *depth = data;

	if ((*depth)--)
		oprofile_add_trace(addr);
}

static struct stacktrace_ops backtrace_ops = {
	.warning = backtrace_warning,
	.warning_symbol = backtrace_warning_symbol,
	.stack = backtrace_stack,
	.address = backtrace_address,
};

/* Limit to stop backtracing too far. */
static int backtrace_limit = 20;

static unsigned long *
user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
{
	unsigned long buf_stack;

	/* Also check accessibility of address */
	if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
		return NULL;

	if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
		return NULL;

	/* Quick paranoia check */
	if (buf_stack & 3)
		return NULL;

	oprofile_add_trace(buf_stack);

	stackaddr++;

	return stackaddr;
}

/*
 * |             | /\ Higher addresses
 * |             |
 * --------------- stack base (address of current_thread_info)
 * | thread info |
 * .             .
 * |    stack    |
 * --------------- saved regs->regs[15] value if valid
 * .             .
 * --------------- struct pt_regs stored on stack (struct pt_regs *)
 * |             |
 * .             .
 * |             |
 * --------------- ???
 * |             |
 * |             | \/ Lower addresses
 *
 * Thus, &pt_regs <-> stack base restricts the valid(ish) fp values
 */
static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs)
{
	unsigned long stack = (unsigned long)regs;
	unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;

	return ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base);
}

void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
{
	unsigned long *stackaddr;

	/*
	 * Paranoia - clip max depth as we could get lost in the weeds.
	 */
	if (depth > backtrace_limit)
		depth = backtrace_limit;

	stackaddr = (unsigned long *)regs->regs[15];
	if (!user_mode(regs)) {
		if (depth)
			dump_trace(NULL, regs, stackaddr,
				   &backtrace_ops, &depth);
		return;
	}

	while (depth-- && (stackaddr != NULL))
		stackaddr = user_backtrace(stackaddr, regs);
}