1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * SH specific backtracing code for oprofile
 4 *
 5 * Copyright 2007 STMicroelectronics Ltd.
 6 *
 7 * Author: Dave Peverley <dpeverley@mpc-data.co.uk>
 8 *
 9 * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
10 * oprofile backtrace code by John Levon, David Smith
11 */
12#include <linux/oprofile.h>
13#include <linux/sched.h>
14#include <linux/kallsyms.h>
15#include <linux/mm.h>
16#include <asm/unwinder.h>
17#include <asm/ptrace.h>
18#include <linux/uaccess.h>
19#include <asm/sections.h>
20#include <asm/stacktrace.h>
21
22static void backtrace_address(void *data, unsigned long addr, int reliable)
23{
24	unsigned int *depth = data;
25
26	if ((*depth)--)
27		oprofile_add_trace(addr);
28}
29
30static struct stacktrace_ops backtrace_ops = {
31	.address = backtrace_address,
32};
33
34/* Limit to stop backtracing too far. */
35static int backtrace_limit = 20;
36
37static unsigned long *
38user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
39{
40	unsigned long buf_stack;
41
42	/* Also check accessibility of address */
43	if (!access_ok(stackaddr, sizeof(unsigned long)))
44		return NULL;
45
46	if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
47		return NULL;
48
49	/* Quick paranoia check */
50	if (buf_stack & 3)
51		return NULL;
52
53	oprofile_add_trace(buf_stack);
54
55	stackaddr++;
56
57	return stackaddr;
58}
59
60void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
61{
62	unsigned long *stackaddr;
63
64	/*
65	 * Paranoia - clip max depth as we could get lost in the weeds.
66	 */
67	if (depth > backtrace_limit)
68		depth = backtrace_limit;
69
70	stackaddr = (unsigned long *)kernel_stack_pointer(regs);
71	if (!user_mode(regs)) {
72		if (depth)
73			unwind_stack(NULL, regs, stackaddr,
74				     &backtrace_ops, &depth);
75		return;
76	}
77
78	while (depth-- && (stackaddr != NULL))
79		stackaddr = user_backtrace(stackaddr, regs);
80}