]>
Commit | Line | Data |
---|---|---|
e5a81b62 SR |
1 | /* |
2 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
3 | * | |
4 | */ | |
5 | #include <linux/stacktrace.h> | |
6 | #include <linux/kallsyms.h> | |
7 | #include <linux/seq_file.h> | |
8 | #include <linux/spinlock.h> | |
9 | #include <linux/uaccess.h> | |
10 | #include <linux/debugfs.h> | |
11 | #include <linux/ftrace.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/fs.h> | |
15 | #include "trace.h" | |
16 | ||
17 | #define STACK_TRACE_ENTRIES 500 | |
18 | ||
19 | static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES] = | |
20 | { [0 ... (STACK_TRACE_ENTRIES-1)] = ULONG_MAX }; | |
21 | static struct stack_trace max_stack_trace = { | |
22 | .max_entries = STACK_TRACE_ENTRIES, | |
23 | .entries = stack_dump_trace, | |
24 | }; | |
25 | ||
26 | static unsigned long max_stack_size; | |
27 | static raw_spinlock_t max_stack_lock = | |
28 | (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; | |
29 | ||
30 | static int stack_trace_disabled __read_mostly; | |
31 | static DEFINE_PER_CPU(int, trace_active); | |
32 | ||
33 | static inline void check_stack(void) | |
34 | { | |
35 | unsigned long this_size; | |
36 | unsigned long flags; | |
37 | ||
38 | this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1); | |
39 | this_size = THREAD_SIZE - this_size; | |
40 | ||
41 | if (this_size <= max_stack_size) | |
42 | return; | |
43 | ||
44 | raw_local_irq_save(flags); | |
45 | __raw_spin_lock(&max_stack_lock); | |
46 | ||
47 | /* a race could have already updated it */ | |
48 | if (this_size <= max_stack_size) | |
49 | goto out; | |
50 | ||
51 | max_stack_size = this_size; | |
52 | ||
53 | max_stack_trace.nr_entries = 0; | |
54 | max_stack_trace.skip = 1; | |
55 | ||
56 | save_stack_trace(&max_stack_trace); | |
57 | ||
58 | out: | |
59 | __raw_spin_unlock(&max_stack_lock); | |
60 | raw_local_irq_restore(flags); | |
61 | } | |
62 | ||
63 | static void | |
64 | stack_trace_call(unsigned long ip, unsigned long parent_ip) | |
65 | { | |
66 | int cpu, resched; | |
67 | ||
68 | if (unlikely(!ftrace_enabled || stack_trace_disabled)) | |
69 | return; | |
70 | ||
71 | resched = need_resched(); | |
72 | preempt_disable_notrace(); | |
73 | ||
74 | cpu = raw_smp_processor_id(); | |
75 | /* no atomic needed, we only modify this variable by this cpu */ | |
76 | if (per_cpu(trace_active, cpu)++ != 0) | |
77 | goto out; | |
78 | ||
79 | check_stack(); | |
80 | ||
81 | out: | |
82 | per_cpu(trace_active, cpu)--; | |
83 | /* prevent recursion in schedule */ | |
84 | if (resched) | |
85 | preempt_enable_no_resched_notrace(); | |
86 | else | |
87 | preempt_enable_notrace(); | |
88 | } | |
89 | ||
90 | static struct ftrace_ops trace_ops __read_mostly = | |
91 | { | |
92 | .func = stack_trace_call, | |
93 | }; | |
94 | ||
95 | static ssize_t | |
96 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
97 | size_t count, loff_t *ppos) | |
98 | { | |
99 | unsigned long *ptr = filp->private_data; | |
100 | char buf[64]; | |
101 | int r; | |
102 | ||
103 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
104 | if (r > sizeof(buf)) | |
105 | r = sizeof(buf); | |
106 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
107 | } | |
108 | ||
109 | static ssize_t | |
110 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
111 | size_t count, loff_t *ppos) | |
112 | { | |
113 | long *ptr = filp->private_data; | |
114 | unsigned long val, flags; | |
115 | char buf[64]; | |
116 | int ret; | |
117 | ||
118 | if (count >= sizeof(buf)) | |
119 | return -EINVAL; | |
120 | ||
121 | if (copy_from_user(&buf, ubuf, count)) | |
122 | return -EFAULT; | |
123 | ||
124 | buf[count] = 0; | |
125 | ||
126 | ret = strict_strtoul(buf, 10, &val); | |
127 | if (ret < 0) | |
128 | return ret; | |
129 | ||
130 | raw_local_irq_save(flags); | |
131 | __raw_spin_lock(&max_stack_lock); | |
132 | *ptr = val; | |
133 | __raw_spin_unlock(&max_stack_lock); | |
134 | raw_local_irq_restore(flags); | |
135 | ||
136 | return count; | |
137 | } | |
138 | ||
139 | static struct file_operations stack_max_size_fops = { | |
140 | .open = tracing_open_generic, | |
141 | .read = stack_max_size_read, | |
142 | .write = stack_max_size_write, | |
143 | }; | |
144 | ||
145 | static void * | |
146 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
147 | { | |
148 | unsigned long *t = m->private; | |
149 | ||
150 | (*pos)++; | |
151 | ||
152 | if (!t || *t == ULONG_MAX) | |
153 | return NULL; | |
154 | ||
155 | t++; | |
156 | m->private = t; | |
157 | ||
158 | return t; | |
159 | } | |
160 | ||
161 | static void *t_start(struct seq_file *m, loff_t *pos) | |
162 | { | |
163 | unsigned long *t = m->private; | |
164 | loff_t l = 0; | |
165 | ||
166 | local_irq_disable(); | |
167 | __raw_spin_lock(&max_stack_lock); | |
168 | ||
169 | for (; t && l < *pos; t = t_next(m, t, &l)) | |
170 | ; | |
171 | ||
172 | return t; | |
173 | } | |
174 | ||
175 | static void t_stop(struct seq_file *m, void *p) | |
176 | { | |
177 | __raw_spin_unlock(&max_stack_lock); | |
178 | local_irq_enable(); | |
179 | } | |
180 | ||
181 | static int trace_lookup_stack(struct seq_file *m, unsigned long addr) | |
182 | { | |
183 | #ifdef CONFIG_KALLSYMS | |
184 | char str[KSYM_SYMBOL_LEN]; | |
185 | ||
186 | sprint_symbol(str, addr); | |
187 | ||
188 | return seq_printf(m, "[<%p>] %s\n", (void*)addr, str); | |
189 | #else | |
190 | return seq_printf(m, "%p\n", (void*)addr); | |
191 | #endif | |
192 | } | |
193 | ||
194 | static int t_show(struct seq_file *m, void *v) | |
195 | { | |
196 | unsigned long *t = v; | |
197 | ||
198 | if (!t || *t == ULONG_MAX) | |
199 | return 0; | |
200 | ||
201 | trace_lookup_stack(m, *t); | |
202 | ||
203 | return 0; | |
204 | } | |
205 | ||
206 | static struct seq_operations stack_trace_seq_ops = { | |
207 | .start = t_start, | |
208 | .next = t_next, | |
209 | .stop = t_stop, | |
210 | .show = t_show, | |
211 | }; | |
212 | ||
213 | static int stack_trace_open(struct inode *inode, struct file *file) | |
214 | { | |
215 | int ret; | |
216 | ||
217 | ret = seq_open(file, &stack_trace_seq_ops); | |
218 | if (!ret) { | |
219 | struct seq_file *m = file->private_data; | |
220 | m->private = stack_dump_trace; | |
221 | } | |
222 | ||
223 | return ret; | |
224 | } | |
225 | ||
226 | static struct file_operations stack_trace_fops = { | |
227 | .open = stack_trace_open, | |
228 | .read = seq_read, | |
229 | .llseek = seq_lseek, | |
230 | }; | |
231 | ||
232 | static __init int stack_trace_init(void) | |
233 | { | |
234 | struct dentry *d_tracer; | |
235 | struct dentry *entry; | |
236 | ||
237 | d_tracer = tracing_init_dentry(); | |
238 | ||
239 | entry = debugfs_create_file("stack_max_size", 0644, d_tracer, | |
240 | &max_stack_size, &stack_max_size_fops); | |
241 | if (!entry) | |
242 | pr_warning("Could not create debugfs 'stack_max_size' entry\n"); | |
243 | ||
244 | entry = debugfs_create_file("stack_trace", 0444, d_tracer, | |
245 | NULL, &stack_trace_fops); | |
246 | if (!entry) | |
247 | pr_warning("Could not create debugfs 'stack_trace' entry\n"); | |
248 | ||
249 | register_ftrace_function(&trace_ops); | |
250 | ||
251 | return 0; | |
252 | } | |
253 | ||
254 | device_initcall(stack_trace_init); |