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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 | ||
1b6cced6 SR |
19 | static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] = |
20 | { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX }; | |
21 | static unsigned stack_dump_index[STACK_TRACE_ENTRIES]; | |
22 | ||
e5a81b62 SR |
23 | static struct stack_trace max_stack_trace = { |
24 | .max_entries = STACK_TRACE_ENTRIES, | |
25 | .entries = stack_dump_trace, | |
26 | }; | |
27 | ||
28 | static unsigned long max_stack_size; | |
29 | static raw_spinlock_t max_stack_lock = | |
30 | (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; | |
31 | ||
32 | static int stack_trace_disabled __read_mostly; | |
33 | static DEFINE_PER_CPU(int, trace_active); | |
34 | ||
35 | static inline void check_stack(void) | |
36 | { | |
1b6cced6 SR |
37 | unsigned long this_size, flags; |
38 | unsigned long *p, *top, *start; | |
39 | int i; | |
e5a81b62 SR |
40 | |
41 | this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1); | |
42 | this_size = THREAD_SIZE - this_size; | |
43 | ||
44 | if (this_size <= max_stack_size) | |
45 | return; | |
46 | ||
81520a1b SR |
47 | /* we do not handle interrupt stacks yet */ |
48 | if (!object_is_on_stack(&this_size)) | |
49 | return; | |
50 | ||
a5e25883 | 51 | local_irq_save(flags); |
e5a81b62 SR |
52 | __raw_spin_lock(&max_stack_lock); |
53 | ||
54 | /* a race could have already updated it */ | |
55 | if (this_size <= max_stack_size) | |
56 | goto out; | |
57 | ||
58 | max_stack_size = this_size; | |
59 | ||
60 | max_stack_trace.nr_entries = 0; | |
1b6cced6 | 61 | max_stack_trace.skip = 3; |
e5a81b62 SR |
62 | |
63 | save_stack_trace(&max_stack_trace); | |
64 | ||
1b6cced6 SR |
65 | /* |
66 | * Now find where in the stack these are. | |
67 | */ | |
68 | i = 0; | |
69 | start = &this_size; | |
70 | top = (unsigned long *) | |
71 | (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); | |
72 | ||
73 | /* | |
74 | * Loop through all the entries. One of the entries may | |
75 | * for some reason be missed on the stack, so we may | |
76 | * have to account for them. If they are all there, this | |
77 | * loop will only happen once. This code only takes place | |
78 | * on a new max, so it is far from a fast path. | |
79 | */ | |
80 | while (i < max_stack_trace.nr_entries) { | |
0a37119d | 81 | int found = 0; |
1b6cced6 SR |
82 | |
83 | stack_dump_index[i] = this_size; | |
84 | p = start; | |
85 | ||
86 | for (; p < top && i < max_stack_trace.nr_entries; p++) { | |
87 | if (*p == stack_dump_trace[i]) { | |
88 | this_size = stack_dump_index[i++] = | |
89 | (top - p) * sizeof(unsigned long); | |
0a37119d | 90 | found = 1; |
1b6cced6 SR |
91 | /* Start the search from here */ |
92 | start = p + 1; | |
93 | } | |
94 | } | |
95 | ||
0a37119d SR |
96 | if (!found) |
97 | i++; | |
1b6cced6 SR |
98 | } |
99 | ||
e5a81b62 SR |
100 | out: |
101 | __raw_spin_unlock(&max_stack_lock); | |
a5e25883 | 102 | local_irq_restore(flags); |
e5a81b62 SR |
103 | } |
104 | ||
105 | static void | |
106 | stack_trace_call(unsigned long ip, unsigned long parent_ip) | |
107 | { | |
108 | int cpu, resched; | |
109 | ||
110 | if (unlikely(!ftrace_enabled || stack_trace_disabled)) | |
111 | return; | |
112 | ||
182e9f5f | 113 | resched = ftrace_preempt_disable(); |
e5a81b62 SR |
114 | |
115 | cpu = raw_smp_processor_id(); | |
116 | /* no atomic needed, we only modify this variable by this cpu */ | |
117 | if (per_cpu(trace_active, cpu)++ != 0) | |
118 | goto out; | |
119 | ||
120 | check_stack(); | |
121 | ||
122 | out: | |
123 | per_cpu(trace_active, cpu)--; | |
124 | /* prevent recursion in schedule */ | |
182e9f5f | 125 | ftrace_preempt_enable(resched); |
e5a81b62 SR |
126 | } |
127 | ||
128 | static struct ftrace_ops trace_ops __read_mostly = | |
129 | { | |
130 | .func = stack_trace_call, | |
131 | }; | |
132 | ||
133 | static ssize_t | |
134 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
135 | size_t count, loff_t *ppos) | |
136 | { | |
137 | unsigned long *ptr = filp->private_data; | |
138 | char buf[64]; | |
139 | int r; | |
140 | ||
141 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
142 | if (r > sizeof(buf)) | |
143 | r = sizeof(buf); | |
144 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
145 | } | |
146 | ||
147 | static ssize_t | |
148 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
149 | size_t count, loff_t *ppos) | |
150 | { | |
151 | long *ptr = filp->private_data; | |
152 | unsigned long val, flags; | |
153 | char buf[64]; | |
154 | int ret; | |
155 | ||
156 | if (count >= sizeof(buf)) | |
157 | return -EINVAL; | |
158 | ||
159 | if (copy_from_user(&buf, ubuf, count)) | |
160 | return -EFAULT; | |
161 | ||
162 | buf[count] = 0; | |
163 | ||
164 | ret = strict_strtoul(buf, 10, &val); | |
165 | if (ret < 0) | |
166 | return ret; | |
167 | ||
a5e25883 | 168 | local_irq_save(flags); |
e5a81b62 SR |
169 | __raw_spin_lock(&max_stack_lock); |
170 | *ptr = val; | |
171 | __raw_spin_unlock(&max_stack_lock); | |
a5e25883 | 172 | local_irq_restore(flags); |
e5a81b62 SR |
173 | |
174 | return count; | |
175 | } | |
176 | ||
177 | static struct file_operations stack_max_size_fops = { | |
178 | .open = tracing_open_generic, | |
179 | .read = stack_max_size_read, | |
180 | .write = stack_max_size_write, | |
181 | }; | |
182 | ||
183 | static void * | |
184 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
185 | { | |
522a110b | 186 | long i; |
e5a81b62 SR |
187 | |
188 | (*pos)++; | |
189 | ||
522a110b LW |
190 | if (v == SEQ_START_TOKEN) |
191 | i = 0; | |
192 | else { | |
193 | i = *(long *)v; | |
194 | i++; | |
195 | } | |
1b6cced6 SR |
196 | |
197 | if (i >= max_stack_trace.nr_entries || | |
198 | stack_dump_trace[i] == ULONG_MAX) | |
e5a81b62 SR |
199 | return NULL; |
200 | ||
1b6cced6 | 201 | m->private = (void *)i; |
e5a81b62 | 202 | |
1b6cced6 | 203 | return &m->private; |
e5a81b62 SR |
204 | } |
205 | ||
206 | static void *t_start(struct seq_file *m, loff_t *pos) | |
207 | { | |
522a110b | 208 | void *t = SEQ_START_TOKEN; |
e5a81b62 SR |
209 | loff_t l = 0; |
210 | ||
211 | local_irq_disable(); | |
212 | __raw_spin_lock(&max_stack_lock); | |
213 | ||
522a110b LW |
214 | if (*pos == 0) |
215 | return SEQ_START_TOKEN; | |
216 | ||
e5a81b62 SR |
217 | for (; t && l < *pos; t = t_next(m, t, &l)) |
218 | ; | |
219 | ||
220 | return t; | |
221 | } | |
222 | ||
223 | static void t_stop(struct seq_file *m, void *p) | |
224 | { | |
225 | __raw_spin_unlock(&max_stack_lock); | |
226 | local_irq_enable(); | |
227 | } | |
228 | ||
1b6cced6 | 229 | static int trace_lookup_stack(struct seq_file *m, long i) |
e5a81b62 | 230 | { |
1b6cced6 | 231 | unsigned long addr = stack_dump_trace[i]; |
e5a81b62 SR |
232 | #ifdef CONFIG_KALLSYMS |
233 | char str[KSYM_SYMBOL_LEN]; | |
234 | ||
235 | sprint_symbol(str, addr); | |
236 | ||
1b6cced6 | 237 | return seq_printf(m, "%s\n", str); |
e5a81b62 SR |
238 | #else |
239 | return seq_printf(m, "%p\n", (void*)addr); | |
240 | #endif | |
241 | } | |
242 | ||
243 | static int t_show(struct seq_file *m, void *v) | |
244 | { | |
522a110b | 245 | long i; |
1b6cced6 SR |
246 | int size; |
247 | ||
522a110b | 248 | if (v == SEQ_START_TOKEN) { |
1b6cced6 SR |
249 | seq_printf(m, " Depth Size Location" |
250 | " (%d entries)\n" | |
251 | " ----- ---- --------\n", | |
252 | max_stack_trace.nr_entries); | |
253 | return 0; | |
254 | } | |
e5a81b62 | 255 | |
522a110b LW |
256 | i = *(long *)v; |
257 | ||
1b6cced6 SR |
258 | if (i >= max_stack_trace.nr_entries || |
259 | stack_dump_trace[i] == ULONG_MAX) | |
e5a81b62 SR |
260 | return 0; |
261 | ||
1b6cced6 SR |
262 | if (i+1 == max_stack_trace.nr_entries || |
263 | stack_dump_trace[i+1] == ULONG_MAX) | |
264 | size = stack_dump_index[i]; | |
265 | else | |
266 | size = stack_dump_index[i] - stack_dump_index[i+1]; | |
267 | ||
268 | seq_printf(m, "%3ld) %8d %5d ", i, stack_dump_index[i], size); | |
269 | ||
270 | trace_lookup_stack(m, i); | |
e5a81b62 SR |
271 | |
272 | return 0; | |
273 | } | |
274 | ||
275 | static struct seq_operations stack_trace_seq_ops = { | |
276 | .start = t_start, | |
277 | .next = t_next, | |
278 | .stop = t_stop, | |
279 | .show = t_show, | |
280 | }; | |
281 | ||
282 | static int stack_trace_open(struct inode *inode, struct file *file) | |
283 | { | |
284 | int ret; | |
285 | ||
286 | ret = seq_open(file, &stack_trace_seq_ops); | |
e5a81b62 SR |
287 | |
288 | return ret; | |
289 | } | |
290 | ||
291 | static struct file_operations stack_trace_fops = { | |
292 | .open = stack_trace_open, | |
293 | .read = seq_read, | |
294 | .llseek = seq_lseek, | |
295 | }; | |
296 | ||
297 | static __init int stack_trace_init(void) | |
298 | { | |
299 | struct dentry *d_tracer; | |
300 | struct dentry *entry; | |
301 | ||
302 | d_tracer = tracing_init_dentry(); | |
303 | ||
304 | entry = debugfs_create_file("stack_max_size", 0644, d_tracer, | |
305 | &max_stack_size, &stack_max_size_fops); | |
306 | if (!entry) | |
307 | pr_warning("Could not create debugfs 'stack_max_size' entry\n"); | |
308 | ||
309 | entry = debugfs_create_file("stack_trace", 0444, d_tracer, | |
310 | NULL, &stack_trace_fops); | |
311 | if (!entry) | |
312 | pr_warning("Could not create debugfs 'stack_trace' entry\n"); | |
313 | ||
314 | register_ftrace_function(&trace_ops); | |
315 | ||
316 | return 0; | |
317 | } | |
318 | ||
319 | device_initcall(stack_trace_init); |