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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 | ||
e5a81b62 SR |
51 | raw_local_irq_save(flags); |
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) { | |
81 | ||
82 | stack_dump_index[i] = this_size; | |
83 | p = start; | |
84 | ||
85 | for (; p < top && i < max_stack_trace.nr_entries; p++) { | |
86 | if (*p == stack_dump_trace[i]) { | |
87 | this_size = stack_dump_index[i++] = | |
88 | (top - p) * sizeof(unsigned long); | |
89 | /* Start the search from here */ | |
90 | start = p + 1; | |
91 | } | |
92 | } | |
93 | ||
94 | i++; | |
95 | } | |
96 | ||
e5a81b62 SR |
97 | out: |
98 | __raw_spin_unlock(&max_stack_lock); | |
99 | raw_local_irq_restore(flags); | |
100 | } | |
101 | ||
102 | static void | |
103 | stack_trace_call(unsigned long ip, unsigned long parent_ip) | |
104 | { | |
105 | int cpu, resched; | |
106 | ||
107 | if (unlikely(!ftrace_enabled || stack_trace_disabled)) | |
108 | return; | |
109 | ||
182e9f5f | 110 | resched = ftrace_preempt_disable(); |
e5a81b62 SR |
111 | |
112 | cpu = raw_smp_processor_id(); | |
113 | /* no atomic needed, we only modify this variable by this cpu */ | |
114 | if (per_cpu(trace_active, cpu)++ != 0) | |
115 | goto out; | |
116 | ||
117 | check_stack(); | |
118 | ||
119 | out: | |
120 | per_cpu(trace_active, cpu)--; | |
121 | /* prevent recursion in schedule */ | |
182e9f5f | 122 | ftrace_preempt_enable(resched); |
e5a81b62 SR |
123 | } |
124 | ||
125 | static struct ftrace_ops trace_ops __read_mostly = | |
126 | { | |
127 | .func = stack_trace_call, | |
128 | }; | |
129 | ||
130 | static ssize_t | |
131 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
132 | size_t count, loff_t *ppos) | |
133 | { | |
134 | unsigned long *ptr = filp->private_data; | |
135 | char buf[64]; | |
136 | int r; | |
137 | ||
138 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
139 | if (r > sizeof(buf)) | |
140 | r = sizeof(buf); | |
141 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
142 | } | |
143 | ||
144 | static ssize_t | |
145 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
146 | size_t count, loff_t *ppos) | |
147 | { | |
148 | long *ptr = filp->private_data; | |
149 | unsigned long val, flags; | |
150 | char buf[64]; | |
151 | int ret; | |
152 | ||
153 | if (count >= sizeof(buf)) | |
154 | return -EINVAL; | |
155 | ||
156 | if (copy_from_user(&buf, ubuf, count)) | |
157 | return -EFAULT; | |
158 | ||
159 | buf[count] = 0; | |
160 | ||
161 | ret = strict_strtoul(buf, 10, &val); | |
162 | if (ret < 0) | |
163 | return ret; | |
164 | ||
165 | raw_local_irq_save(flags); | |
166 | __raw_spin_lock(&max_stack_lock); | |
167 | *ptr = val; | |
168 | __raw_spin_unlock(&max_stack_lock); | |
169 | raw_local_irq_restore(flags); | |
170 | ||
171 | return count; | |
172 | } | |
173 | ||
174 | static struct file_operations stack_max_size_fops = { | |
175 | .open = tracing_open_generic, | |
176 | .read = stack_max_size_read, | |
177 | .write = stack_max_size_write, | |
178 | }; | |
179 | ||
180 | static void * | |
181 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
182 | { | |
522a110b | 183 | long i; |
e5a81b62 SR |
184 | |
185 | (*pos)++; | |
186 | ||
522a110b LW |
187 | if (v == SEQ_START_TOKEN) |
188 | i = 0; | |
189 | else { | |
190 | i = *(long *)v; | |
191 | i++; | |
192 | } | |
1b6cced6 SR |
193 | |
194 | if (i >= max_stack_trace.nr_entries || | |
195 | stack_dump_trace[i] == ULONG_MAX) | |
e5a81b62 SR |
196 | return NULL; |
197 | ||
1b6cced6 | 198 | m->private = (void *)i; |
e5a81b62 | 199 | |
1b6cced6 | 200 | return &m->private; |
e5a81b62 SR |
201 | } |
202 | ||
203 | static void *t_start(struct seq_file *m, loff_t *pos) | |
204 | { | |
522a110b | 205 | void *t = SEQ_START_TOKEN; |
e5a81b62 SR |
206 | loff_t l = 0; |
207 | ||
208 | local_irq_disable(); | |
209 | __raw_spin_lock(&max_stack_lock); | |
210 | ||
522a110b LW |
211 | if (*pos == 0) |
212 | return SEQ_START_TOKEN; | |
213 | ||
e5a81b62 SR |
214 | for (; t && l < *pos; t = t_next(m, t, &l)) |
215 | ; | |
216 | ||
217 | return t; | |
218 | } | |
219 | ||
220 | static void t_stop(struct seq_file *m, void *p) | |
221 | { | |
222 | __raw_spin_unlock(&max_stack_lock); | |
223 | local_irq_enable(); | |
224 | } | |
225 | ||
1b6cced6 | 226 | static int trace_lookup_stack(struct seq_file *m, long i) |
e5a81b62 | 227 | { |
1b6cced6 | 228 | unsigned long addr = stack_dump_trace[i]; |
e5a81b62 SR |
229 | #ifdef CONFIG_KALLSYMS |
230 | char str[KSYM_SYMBOL_LEN]; | |
231 | ||
232 | sprint_symbol(str, addr); | |
233 | ||
1b6cced6 | 234 | return seq_printf(m, "%s\n", str); |
e5a81b62 SR |
235 | #else |
236 | return seq_printf(m, "%p\n", (void*)addr); | |
237 | #endif | |
238 | } | |
239 | ||
240 | static int t_show(struct seq_file *m, void *v) | |
241 | { | |
522a110b | 242 | long i; |
1b6cced6 SR |
243 | int size; |
244 | ||
522a110b | 245 | if (v == SEQ_START_TOKEN) { |
1b6cced6 SR |
246 | seq_printf(m, " Depth Size Location" |
247 | " (%d entries)\n" | |
248 | " ----- ---- --------\n", | |
249 | max_stack_trace.nr_entries); | |
250 | return 0; | |
251 | } | |
e5a81b62 | 252 | |
522a110b LW |
253 | i = *(long *)v; |
254 | ||
1b6cced6 SR |
255 | if (i >= max_stack_trace.nr_entries || |
256 | stack_dump_trace[i] == ULONG_MAX) | |
e5a81b62 SR |
257 | return 0; |
258 | ||
1b6cced6 SR |
259 | if (i+1 == max_stack_trace.nr_entries || |
260 | stack_dump_trace[i+1] == ULONG_MAX) | |
261 | size = stack_dump_index[i]; | |
262 | else | |
263 | size = stack_dump_index[i] - stack_dump_index[i+1]; | |
264 | ||
265 | seq_printf(m, "%3ld) %8d %5d ", i, stack_dump_index[i], size); | |
266 | ||
267 | trace_lookup_stack(m, i); | |
e5a81b62 SR |
268 | |
269 | return 0; | |
270 | } | |
271 | ||
272 | static struct seq_operations stack_trace_seq_ops = { | |
273 | .start = t_start, | |
274 | .next = t_next, | |
275 | .stop = t_stop, | |
276 | .show = t_show, | |
277 | }; | |
278 | ||
279 | static int stack_trace_open(struct inode *inode, struct file *file) | |
280 | { | |
281 | int ret; | |
282 | ||
283 | ret = seq_open(file, &stack_trace_seq_ops); | |
e5a81b62 SR |
284 | |
285 | return ret; | |
286 | } | |
287 | ||
288 | static struct file_operations stack_trace_fops = { | |
289 | .open = stack_trace_open, | |
290 | .read = seq_read, | |
291 | .llseek = seq_lseek, | |
292 | }; | |
293 | ||
294 | static __init int stack_trace_init(void) | |
295 | { | |
296 | struct dentry *d_tracer; | |
297 | struct dentry *entry; | |
298 | ||
299 | d_tracer = tracing_init_dentry(); | |
300 | ||
301 | entry = debugfs_create_file("stack_max_size", 0644, d_tracer, | |
302 | &max_stack_size, &stack_max_size_fops); | |
303 | if (!entry) | |
304 | pr_warning("Could not create debugfs 'stack_max_size' entry\n"); | |
305 | ||
306 | entry = debugfs_create_file("stack_trace", 0444, d_tracer, | |
307 | NULL, &stack_trace_fops); | |
308 | if (!entry) | |
309 | pr_warning("Could not create debugfs 'stack_trace' entry\n"); | |
310 | ||
311 | register_ftrace_function(&trace_ops); | |
312 | ||
313 | return 0; | |
314 | } | |
315 | ||
316 | device_initcall(stack_trace_init); |