1/*
2 * Stack trace management functions
3 *
4 *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
5 */
6#include <linux/sched.h>
7#include <linux/stacktrace.h>
8#include <linux/module.h>
9#include <linux/uaccess.h>
10#include <asm/stacktrace.h>
11
12static int save_stack_stack(void *data, char *name)
13{
14	return 0;
15}
16
17static void
18__save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched)
19{
20	struct stack_trace *trace = data;
21#ifdef CONFIG_FRAME_POINTER
22	if (!reliable)
23		return;
24#endif
25	if (nosched && in_sched_functions(addr))
26		return;
27	if (trace->skip > 0) {
28		trace->skip--;
29		return;
30	}
31	if (trace->nr_entries < trace->max_entries)
32		trace->entries[trace->nr_entries++] = addr;
33}
34
35static void save_stack_address(void *data, unsigned long addr, int reliable)
36{
37	return __save_stack_address(data, addr, reliable, false);
38}
39
40static void
41save_stack_address_nosched(void *data, unsigned long addr, int reliable)
42{
43	return __save_stack_address(data, addr, reliable, true);
44}
45
46static const struct stacktrace_ops save_stack_ops = {
47	.stack		= save_stack_stack,
48	.address	= save_stack_address,
49	.walk_stack	= print_context_stack,
50};
51
52static const struct stacktrace_ops save_stack_ops_nosched = {
53	.stack		= save_stack_stack,
54	.address	= save_stack_address_nosched,
55	.walk_stack	= print_context_stack,
56};
57
58/*
59 * Save stack-backtrace addresses into a stack_trace buffer.
60 */
61void save_stack_trace(struct stack_trace *trace)
62{
63	dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
64	if (trace->nr_entries < trace->max_entries)
65		trace->entries[trace->nr_entries++] = ULONG_MAX;
66}
67EXPORT_SYMBOL_GPL(save_stack_trace);
68
69void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
70{
71	dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
72	if (trace->nr_entries < trace->max_entries)
73		trace->entries[trace->nr_entries++] = ULONG_MAX;
74}
75
76void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
77{
78	dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
79	if (trace->nr_entries < trace->max_entries)
80		trace->entries[trace->nr_entries++] = ULONG_MAX;
81}
82EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
83
84/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
85
86struct stack_frame_user {
87	const void __user	*next_fp;
88	unsigned long		ret_addr;
89};
90
91static int
92copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
93{
94	int ret;
95
96	if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
97		return 0;
98
99	ret = 1;
100	pagefault_disable();
101	if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
102		ret = 0;
103	pagefault_enable();
104
105	return ret;
106}
107
108static inline void __save_stack_trace_user(struct stack_trace *trace)
109{
110	const struct pt_regs *regs = task_pt_regs(current);
111	const void __user *fp = (const void __user *)regs->bp;
112
113	if (trace->nr_entries < trace->max_entries)
114		trace->entries[trace->nr_entries++] = regs->ip;
115
116	while (trace->nr_entries < trace->max_entries) {
117		struct stack_frame_user frame;
118
119		frame.next_fp = NULL;
120		frame.ret_addr = 0;
121		if (!copy_stack_frame(fp, &frame))
122			break;
123		if ((unsigned long)fp < regs->sp)
124			break;
125		if (frame.ret_addr) {
126			trace->entries[trace->nr_entries++] =
127				frame.ret_addr;
128		}
129		if (fp == frame.next_fp)
130			break;
131		fp = frame.next_fp;
132	}
133}
134
135void save_stack_trace_user(struct stack_trace *trace)
136{
137	/*
138	 * Trace user stack if we are not a kernel thread
139	 */
140	if (current->mm) {
141		__save_stack_trace_user(trace);
142	}
143	if (trace->nr_entries < trace->max_entries)
144		trace->entries[trace->nr_entries++] = ULONG_MAX;
145}
146
147