1
2
3
4
5
6
7
8
9
10
11#include "qemu/osdep.h"
12#ifndef _WIN32
13#include <pthread.h>
14#endif
15#include "qemu/timer.h"
16#include "trace.h"
17#include "trace/control.h"
18#include "trace/simple.h"
19
20
21#define HEADER_EVENT_ID (~(uint64_t)0)
22
23
24#define HEADER_MAGIC 0xf2b177cb0aa429b4ULL
25
26
27#define HEADER_VERSION 3
28
29
30#define DROPPED_EVENT_ID (~(uint64_t)0 - 1)
31
32
33#define TRACE_RECORD_VALID ((uint64_t)1 << 63)
34
35
36
37
38
39static CompatGMutex trace_lock;
40static CompatGCond trace_available_cond;
41static CompatGCond trace_empty_cond;
42
43static bool trace_available;
44static bool trace_writeout_enabled;
45
46enum {
47 TRACE_BUF_LEN = 4096 * 64,
48 TRACE_BUF_FLUSH_THRESHOLD = TRACE_BUF_LEN / 4,
49};
50
51uint8_t trace_buf[TRACE_BUF_LEN];
52static volatile gint trace_idx;
53static unsigned int writeout_idx;
54static volatile gint dropped_events;
55static uint32_t trace_pid;
56static FILE *trace_fp;
57static char *trace_file_name;
58
59
60typedef struct {
61 uint64_t event;
62 uint64_t timestamp_ns;
63 uint32_t length;
64 uint32_t pid;
65 uint64_t arguments[];
66} TraceRecord;
67
68typedef struct {
69 uint64_t header_event_id;
70 uint64_t header_magic;
71 uint64_t header_version;
72} TraceLogHeader;
73
74
75static void read_from_buffer(unsigned int idx, void *dataptr, size_t size);
76static unsigned int write_to_buffer(unsigned int idx, void *dataptr, size_t size);
77
78static void clear_buffer_range(unsigned int idx, size_t len)
79{
80 uint32_t num = 0;
81 while (num < len) {
82 if (idx >= TRACE_BUF_LEN) {
83 idx = idx % TRACE_BUF_LEN;
84 }
85 trace_buf[idx++] = 0;
86 num++;
87 }
88}
89
90
91
92
93
94
95
96
97static bool get_trace_record(unsigned int idx, TraceRecord **recordptr)
98{
99 uint64_t event_flag = 0;
100 TraceRecord record;
101
102 read_from_buffer(idx, &record, sizeof(event_flag));
103
104 if (!(record.event & TRACE_RECORD_VALID)) {
105 return false;
106 }
107
108 smp_rmb();
109
110 read_from_buffer(idx, &record, sizeof(TraceRecord));
111 *recordptr = malloc(record.length);
112
113 read_from_buffer(idx, *recordptr, record.length);
114 smp_rmb();
115 (*recordptr)->event &= ~TRACE_RECORD_VALID;
116
117
118
119
120 clear_buffer_range(idx, record.length);
121 return true;
122}
123
124
125
126
127
128
129static void flush_trace_file(bool wait)
130{
131 g_mutex_lock(&trace_lock);
132 trace_available = true;
133 g_cond_signal(&trace_available_cond);
134
135 if (wait) {
136 g_cond_wait(&trace_empty_cond, &trace_lock);
137 }
138
139 g_mutex_unlock(&trace_lock);
140}
141
142static void wait_for_trace_records_available(void)
143{
144 g_mutex_lock(&trace_lock);
145 while (!(trace_available && trace_writeout_enabled)) {
146 g_cond_signal(&trace_empty_cond);
147 g_cond_wait(&trace_available_cond, &trace_lock);
148 }
149 trace_available = false;
150 g_mutex_unlock(&trace_lock);
151}
152
153static gpointer writeout_thread(gpointer opaque)
154{
155 TraceRecord *recordptr;
156 union {
157 TraceRecord rec;
158 uint8_t bytes[sizeof(TraceRecord) + sizeof(uint64_t)];
159 } dropped;
160 unsigned int idx = 0;
161 int dropped_count;
162 size_t unused __attribute__ ((unused));
163
164 for (;;) {
165 wait_for_trace_records_available();
166
167 if (g_atomic_int_get(&dropped_events)) {
168 dropped.rec.event = DROPPED_EVENT_ID,
169 dropped.rec.timestamp_ns = get_clock();
170 dropped.rec.length = sizeof(TraceRecord) + sizeof(uint64_t),
171 dropped.rec.pid = trace_pid;
172 do {
173 dropped_count = g_atomic_int_get(&dropped_events);
174 } while (!g_atomic_int_compare_and_exchange(&dropped_events,
175 dropped_count, 0));
176 dropped.rec.arguments[0] = dropped_count;
177 unused = fwrite(&dropped.rec, dropped.rec.length, 1, trace_fp);
178 }
179
180 while (get_trace_record(idx, &recordptr)) {
181 unused = fwrite(recordptr, recordptr->length, 1, trace_fp);
182 writeout_idx += recordptr->length;
183 free(recordptr);
184 idx = writeout_idx % TRACE_BUF_LEN;
185 }
186
187 fflush(trace_fp);
188 }
189 return NULL;
190}
191
192void trace_record_write_u64(TraceBufferRecord *rec, uint64_t val)
193{
194 rec->rec_off = write_to_buffer(rec->rec_off, &val, sizeof(uint64_t));
195}
196
197void trace_record_write_str(TraceBufferRecord *rec, const char *s, uint32_t slen)
198{
199
200 rec->rec_off = write_to_buffer(rec->rec_off, &slen, sizeof(slen));
201
202 rec->rec_off = write_to_buffer(rec->rec_off, (void*)s, slen);
203}
204
205int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasize)
206{
207 unsigned int idx, rec_off, old_idx, new_idx;
208 uint32_t rec_len = sizeof(TraceRecord) + datasize;
209 uint64_t event_u64 = event;
210 uint64_t timestamp_ns = get_clock();
211
212 do {
213 old_idx = g_atomic_int_get(&trace_idx);
214 smp_rmb();
215 new_idx = old_idx + rec_len;
216
217 if (new_idx - writeout_idx > TRACE_BUF_LEN) {
218
219 g_atomic_int_inc(&dropped_events);
220 return -ENOSPC;
221 }
222 } while (!g_atomic_int_compare_and_exchange(&trace_idx, old_idx, new_idx));
223
224 idx = old_idx % TRACE_BUF_LEN;
225
226 rec_off = idx;
227 rec_off = write_to_buffer(rec_off, &event_u64, sizeof(event_u64));
228 rec_off = write_to_buffer(rec_off, ×tamp_ns, sizeof(timestamp_ns));
229 rec_off = write_to_buffer(rec_off, &rec_len, sizeof(rec_len));
230 rec_off = write_to_buffer(rec_off, &trace_pid, sizeof(trace_pid));
231
232 rec->tbuf_idx = idx;
233 rec->rec_off = (idx + sizeof(TraceRecord)) % TRACE_BUF_LEN;
234 return 0;
235}
236
237static void read_from_buffer(unsigned int idx, void *dataptr, size_t size)
238{
239 uint8_t *data_ptr = dataptr;
240 uint32_t x = 0;
241 while (x < size) {
242 if (idx >= TRACE_BUF_LEN) {
243 idx = idx % TRACE_BUF_LEN;
244 }
245 data_ptr[x++] = trace_buf[idx++];
246 }
247}
248
249static unsigned int write_to_buffer(unsigned int idx, void *dataptr, size_t size)
250{
251 uint8_t *data_ptr = dataptr;
252 uint32_t x = 0;
253 while (x < size) {
254 if (idx >= TRACE_BUF_LEN) {
255 idx = idx % TRACE_BUF_LEN;
256 }
257 trace_buf[idx++] = data_ptr[x++];
258 }
259 return idx;
260}
261
262void trace_record_finish(TraceBufferRecord *rec)
263{
264 TraceRecord record;
265 read_from_buffer(rec->tbuf_idx, &record, sizeof(TraceRecord));
266 smp_wmb();
267 record.event |= TRACE_RECORD_VALID;
268 write_to_buffer(rec->tbuf_idx, &record, sizeof(TraceRecord));
269
270 if (((unsigned int)g_atomic_int_get(&trace_idx) - writeout_idx)
271 > TRACE_BUF_FLUSH_THRESHOLD) {
272 flush_trace_file(false);
273 }
274}
275
276void st_set_trace_file_enabled(bool enable)
277{
278 if (enable == !!trace_fp) {
279 return;
280 }
281
282
283 flush_trace_file(true);
284 trace_writeout_enabled = false;
285 flush_trace_file(true);
286
287 if (enable) {
288 static const TraceLogHeader header = {
289 .header_event_id = HEADER_EVENT_ID,
290 .header_magic = HEADER_MAGIC,
291
292 .header_version = HEADER_VERSION,
293 };
294
295 trace_fp = fopen(trace_file_name, "wb");
296 if (!trace_fp) {
297 return;
298 }
299
300 if (fwrite(&header, sizeof header, 1, trace_fp) != 1) {
301 fclose(trace_fp);
302 trace_fp = NULL;
303 return;
304 }
305
306
307 trace_writeout_enabled = true;
308 flush_trace_file(false);
309 } else {
310 fclose(trace_fp);
311 trace_fp = NULL;
312 }
313}
314
315
316
317
318
319
320
321void st_set_trace_file(const char *file)
322{
323 st_set_trace_file_enabled(false);
324
325 g_free(trace_file_name);
326
327 if (!file) {
328
329 trace_file_name = g_strdup_printf(CONFIG_TRACE_FILE, (pid_t)getpid());
330 } else {
331 trace_file_name = g_strdup_printf("%s", file);
332 }
333
334 st_set_trace_file_enabled(true);
335}
336
337void st_print_trace_file_status(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
338{
339 stream_printf(stream, "Trace file \"%s\" %s.\n",
340 trace_file_name, trace_fp ? "on" : "off");
341}
342
343void st_flush_trace_buffer(void)
344{
345 flush_trace_file(true);
346}
347
348
349
350
351
352
353static GThread *trace_thread_create(GThreadFunc fn)
354{
355 GThread *thread;
356#ifndef _WIN32
357 sigset_t set, oldset;
358
359 sigfillset(&set);
360 pthread_sigmask(SIG_SETMASK, &set, &oldset);
361#endif
362
363 thread = g_thread_new("trace-thread", fn, NULL);
364
365#ifndef _WIN32
366 pthread_sigmask(SIG_SETMASK, &oldset, NULL);
367#endif
368
369 return thread;
370}
371
372bool st_init(void)
373{
374 GThread *thread;
375
376 trace_pid = getpid();
377
378 thread = trace_thread_create(writeout_thread);
379 if (!thread) {
380 fprintf(stderr, "warning: unable to initialize simple trace backend\n");
381 return false;
382 }
383
384 atexit(st_flush_trace_buffer);
385 return true;
386}
387