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 int backtrace_stack(void *data, char *name)
23{
24	/* Yes, we want all stacks */
25	return 0;
26}
27
28static void backtrace_address(void *data, unsigned long addr, int reliable)
29{
30	unsigned int *depth = data;
31
32	if ((*depth)--)
33		oprofile_add_trace(addr);
34}
35
36static struct stacktrace_ops backtrace_ops = {
37	.stack = backtrace_stack,
38	.address = backtrace_address,
39};
40
41/* Limit to stop backtracing too far. */
42static int backtrace_limit = 20;
43
44static unsigned long *
45user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
46{
47	unsigned long buf_stack;
48
49	/* Also check accessibility of address */
50	if (!access_ok(stackaddr, sizeof(unsigned long)))
51		return NULL;
52
53	if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
54		return NULL;
55
56	/* Quick paranoia check */
57	if (buf_stack & 3)
58		return NULL;
59
60	oprofile_add_trace(buf_stack);
61
62	stackaddr++;
63
64	return stackaddr;
65}
66
67void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
68{
69	unsigned long *stackaddr;
70
71	/*
72	 * Paranoia - clip max depth as we could get lost in the weeds.
73	 */
74	if (depth > backtrace_limit)
75		depth = backtrace_limit;
76
77	stackaddr = (unsigned long *)kernel_stack_pointer(regs);
78	if (!user_mode(regs)) {
79		if (depth)
80			unwind_stack(NULL, regs, stackaddr,
81				     &backtrace_ops, &depth);
82		return;
83	}
84
85	while (depth-- && (stackaddr != NULL))
86		stackaddr = user_backtrace(stackaddr, regs);
87}