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8#include <linux/kallsyms.h>
9#include <linux/debugfs.h>
10#include <linux/hrtimer.h>
11#include <linux/uaccess.h>
12#include <linux/ftrace.h>
13#include <linux/module.h>
14#include <linux/irq.h>
15#include <linux/fs.h>
16
17#include <asm/stacktrace.h>
18
19#include "trace.h"
20
21static struct trace_array *sysprof_trace;
22static int __read_mostly tracer_enabled;
23
24
25
26
27static unsigned long sample_period = 1000000;
28static const unsigned int sample_max_depth = 512;
29
30static DEFINE_MUTEX(sample_timer_lock);
31
32
33
34static DEFINE_PER_CPU(struct hrtimer, stack_trace_hrtimer);
35
36struct stack_frame {
37 const void __user *next_fp;
38 unsigned long return_address;
39};
40
41static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
42{
43 int ret;
44
45 if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
46 return 0;
47
48 ret = 1;
49 pagefault_disable();
50 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
51 ret = 0;
52 pagefault_enable();
53
54 return ret;
55}
56
57struct backtrace_info {
58 struct trace_array_cpu *data;
59 struct trace_array *tr;
60 int pos;
61};
62
63static void
64backtrace_warning_symbol(void *data, char *msg, unsigned long symbol)
65{
66
67}
68
69static void backtrace_warning(void *data, char *msg)
70{
71
72}
73
74static int backtrace_stack(void *data, char *name)
75{
76
77 return -1;
78}
79
80static void backtrace_address(void *data, unsigned long addr, int reliable)
81{
82 struct backtrace_info *info = data;
83
84 if (info->pos < sample_max_depth && reliable) {
85 __trace_special(info->tr, info->data, 1, addr, 0);
86
87 info->pos++;
88 }
89}
90
91static const struct stacktrace_ops backtrace_ops = {
92 .warning = backtrace_warning,
93 .warning_symbol = backtrace_warning_symbol,
94 .stack = backtrace_stack,
95 .address = backtrace_address,
96};
97
98static int
99trace_kernel(struct pt_regs *regs, struct trace_array *tr,
100 struct trace_array_cpu *data)
101{
102 struct backtrace_info info;
103 unsigned long bp;
104 char *stack;
105
106 info.tr = tr;
107 info.data = data;
108 info.pos = 1;
109
110 __trace_special(info.tr, info.data, 1, regs->ip, 0);
111
112 stack = ((char *)regs + sizeof(struct pt_regs));
113#ifdef CONFIG_FRAME_POINTER
114 bp = regs->bp;
115#else
116 bp = 0;
117#endif
118
119 dump_trace(NULL, regs, (void *)stack, bp, &backtrace_ops, &info);
120
121 return info.pos;
122}
123
124static void timer_notify(struct pt_regs *regs, int cpu)
125{
126 struct trace_array_cpu *data;
127 struct stack_frame frame;
128 struct trace_array *tr;
129 const void __user *fp;
130 int is_user;
131 int i;
132
133 if (!regs)
134 return;
135
136 tr = sysprof_trace;
137 data = tr->data[cpu];
138 is_user = user_mode(regs);
139
140 if (!current || current->pid == 0)
141 return;
142
143 if (is_user && current->state != TASK_RUNNING)
144 return;
145
146 __trace_special(tr, data, 0, 0, current->pid);
147
148 if (!is_user)
149 i = trace_kernel(regs, tr, data);
150 else
151 i = 0;
152
153
154
155
156 if (current->mm && i < sample_max_depth) {
157 regs = (struct pt_regs *)current->thread.sp0 - 1;
158
159 fp = (void __user *)regs->bp;
160
161 __trace_special(tr, data, 2, regs->ip, 0);
162
163 while (i < sample_max_depth) {
164 frame.next_fp = NULL;
165 frame.return_address = 0;
166 if (!copy_stack_frame(fp, &frame))
167 break;
168 if ((unsigned long)fp < regs->sp)
169 break;
170
171 __trace_special(tr, data, 2, frame.return_address,
172 (unsigned long)fp);
173 fp = frame.next_fp;
174
175 i++;
176 }
177
178 }
179
180
181
182
183 if (i == sample_max_depth)
184 __trace_special(tr, data, -1, -1, -1);
185
186 __trace_special(tr, data, 3, current->pid, i);
187}
188
189static enum hrtimer_restart stack_trace_timer_fn(struct hrtimer *hrtimer)
190{
191
192 timer_notify(get_irq_regs(), smp_processor_id());
193
194 hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
195
196 return HRTIMER_RESTART;
197}
198
199static void start_stack_timer(void *unused)
200{
201 struct hrtimer *hrtimer = &__get_cpu_var(stack_trace_hrtimer);
202
203 hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
204 hrtimer->function = stack_trace_timer_fn;
205
206 hrtimer_start(hrtimer, ns_to_ktime(sample_period),
207 HRTIMER_MODE_REL_PINNED);
208}
209
210static void start_stack_timers(void)
211{
212 on_each_cpu(start_stack_timer, NULL, 1);
213}
214
215static void stop_stack_timer(int cpu)
216{
217 struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu);
218
219 hrtimer_cancel(hrtimer);
220}
221
222static void stop_stack_timers(void)
223{
224 int cpu;
225
226 for_each_online_cpu(cpu)
227 stop_stack_timer(cpu);
228}
229
230static void stop_stack_trace(struct trace_array *tr)
231{
232 mutex_lock(&sample_timer_lock);
233 stop_stack_timers();
234 tracer_enabled = 0;
235 mutex_unlock(&sample_timer_lock);
236}
237
238static int stack_trace_init(struct trace_array *tr)
239{
240 sysprof_trace = tr;
241
242 tracing_start_cmdline_record();
243
244 mutex_lock(&sample_timer_lock);
245 start_stack_timers();
246 tracer_enabled = 1;
247 mutex_unlock(&sample_timer_lock);
248 return 0;
249}
250
251static void stack_trace_reset(struct trace_array *tr)
252{
253 tracing_stop_cmdline_record();
254 stop_stack_trace(tr);
255}
256
257static struct tracer stack_trace __read_mostly =
258{
259 .name = "sysprof",
260 .init = stack_trace_init,
261 .reset = stack_trace_reset,
262#ifdef CONFIG_FTRACE_SELFTEST
263 .selftest = trace_selftest_startup_sysprof,
264#endif
265};
266
267__init static int init_stack_trace(void)
268{
269 return register_tracer(&stack_trace);
270}
271device_initcall(init_stack_trace);
272
273#define MAX_LONG_DIGITS 22
274
275static ssize_t
276sysprof_sample_read(struct file *filp, char __user *ubuf,
277 size_t cnt, loff_t *ppos)
278{
279 char buf[MAX_LONG_DIGITS];
280 int r;
281
282 r = sprintf(buf, "%ld\n", nsecs_to_usecs(sample_period));
283
284 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
285}
286
287static ssize_t
288sysprof_sample_write(struct file *filp, const char __user *ubuf,
289 size_t cnt, loff_t *ppos)
290{
291 char buf[MAX_LONG_DIGITS];
292 unsigned long val;
293
294 if (cnt > MAX_LONG_DIGITS-1)
295 cnt = MAX_LONG_DIGITS-1;
296
297 if (copy_from_user(&buf, ubuf, cnt))
298 return -EFAULT;
299
300 buf[cnt] = 0;
301
302 val = simple_strtoul(buf, NULL, 10);
303
304
305
306 if (val < 100)
307 val = 100;
308
309 mutex_lock(&sample_timer_lock);
310 stop_stack_timers();
311 sample_period = val * 1000;
312 start_stack_timers();
313 mutex_unlock(&sample_timer_lock);
314
315 return cnt;
316}
317
318static const struct file_operations sysprof_sample_fops = {
319 .read = sysprof_sample_read,
320 .write = sysprof_sample_write,
321};
322
323void init_tracer_sysprof_debugfs(struct dentry *d_tracer)
324{
325
326 trace_create_file("sysprof_sample_period", 0644,
327 d_tracer, NULL, &sysprof_sample_fops);
328}
329