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
backtrace_address(void * data,unsigned long addr,int reliable)22 static 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
30 static struct stacktrace_ops backtrace_ops = {
31 .address = backtrace_address,
32 };
33
34 /* Limit to stop backtracing too far. */
35 static int backtrace_limit = 20;
36
37 static unsigned long *
user_backtrace(unsigned long * stackaddr,struct pt_regs * regs)38 user_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
sh_backtrace(struct pt_regs * const regs,unsigned int depth)60 void 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 }
81
