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
backtrace_stack(void * data,char * name)26 static int backtrace_stack(void *data, char *name)
27 {
28 /* Yes, we want all stacks */
29 return 0;
30 }
31
backtrace_address(void * data,unsigned long addr,int reliable)32 static 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
40 static struct stacktrace_ops backtrace_ops = {
41 .stack = backtrace_stack,
42 .address = backtrace_address,
43 };
44
45 /* Limit to stop backtracing too far. */
46 static int backtrace_limit = 20;
47
48 static unsigned long *
user_backtrace(unsigned long * stackaddr,struct pt_regs * regs)49 user_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
sh_backtrace(struct pt_regs * const regs,unsigned int depth)71 void 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