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_warning_symbol(void * data,char * msg,unsigned long symbol)26 static void backtrace_warning_symbol(void *data, char *msg,
27 unsigned long symbol)
28 {
29 /* Ignore warnings */
30 }
31
backtrace_warning(void * data,char * msg)32 static void backtrace_warning(void *data, char *msg)
33 {
34 /* Ignore warnings */
35 }
36
backtrace_stack(void * data,char * name)37 static int backtrace_stack(void *data, char *name)
38 {
39 /* Yes, we want all stacks */
40 return 0;
41 }
42
backtrace_address(void * data,unsigned long addr,int reliable)43 static void backtrace_address(void *data, unsigned long addr, int reliable)
44 {
45 unsigned int *depth = data;
46
47 if ((*depth)--)
48 oprofile_add_trace(addr);
49 }
50
51 static struct stacktrace_ops backtrace_ops = {
52 .warning = backtrace_warning,
53 .warning_symbol = backtrace_warning_symbol,
54 .stack = backtrace_stack,
55 .address = backtrace_address,
56 };
57
58 /* Limit to stop backtracing too far. */
59 static int backtrace_limit = 20;
60
61 static unsigned long *
user_backtrace(unsigned long * stackaddr,struct pt_regs * regs)62 user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
63 {
64 unsigned long buf_stack;
65
66 /* Also check accessibility of address */
67 if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
68 return NULL;
69
70 if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
71 return NULL;
72
73 /* Quick paranoia check */
74 if (buf_stack & 3)
75 return NULL;
76
77 oprofile_add_trace(buf_stack);
78
79 stackaddr++;
80
81 return stackaddr;
82 }
83
sh_backtrace(struct pt_regs * const regs,unsigned int depth)84 void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
85 {
86 unsigned long *stackaddr;
87
88 /*
89 * Paranoia - clip max depth as we could get lost in the weeds.
90 */
91 if (depth > backtrace_limit)
92 depth = backtrace_limit;
93
94 stackaddr = (unsigned long *)kernel_stack_pointer(regs);
95 if (!user_mode(regs)) {
96 if (depth)
97 unwind_stack(NULL, regs, stackaddr,
98 &backtrace_ops, &depth);
99 return;
100 }
101
102 while (depth-- && (stackaddr != NULL))
103 stackaddr = user_backtrace(stackaddr, regs);
104 }
105