[qemu.git] / trace / simple.c

/*
 * Simple trace backend
 *
 * Copyright IBM, Corp. 2010
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 */

#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <time.h>
#include <signal.h>
#include <pthread.h>
#include "qemu-timer.h"
#include "trace.h"
#include "trace/control.h"

/** Trace file header event ID */
#define HEADER_EVENT_ID (~(uint64_t)0) /* avoids conflicting with TraceEventIDs */

/** Trace file magic number */
#define HEADER_MAGIC 0xf2b177cb0aa429b4ULL

/** Trace file version number, bump if format changes */
#define HEADER_VERSION 0

/** Records were dropped event ID */
#define DROPPED_EVENT_ID (~(uint64_t)0 - 1)

/** Trace record is valid */
#define TRACE_RECORD_VALID ((uint64_t)1 << 63)

/** Trace buffer entry */
typedef struct {
    uint64_t event;
    uint64_t timestamp_ns;
    uint64_t x1;
    uint64_t x2;
    uint64_t x3;
    uint64_t x4;
    uint64_t x5;
    uint64_t x6;
} TraceRecord;

enum {
    TRACE_BUF_LEN = 4096,
    TRACE_BUF_FLUSH_THRESHOLD = TRACE_BUF_LEN / 4,
};

/*
 * Trace records are written out by a dedicated thread.  The thread waits for
 * records to become available, writes them out, and then waits again.
 */
static pthread_mutex_t trace_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t trace_available_cond = PTHREAD_COND_INITIALIZER;
static pthread_cond_t trace_empty_cond = PTHREAD_COND_INITIALIZER;
static bool trace_available;
static bool trace_writeout_enabled;

static TraceRecord trace_buf[TRACE_BUF_LEN];
static unsigned int trace_idx;
static FILE *trace_fp;
static char *trace_file_name = NULL;

/**
 * Read a trace record from the trace buffer
 *
 * @idx         Trace buffer index
 * @record      Trace record to fill
 *
 * Returns false if the record is not valid.
 */
static bool get_trace_record(unsigned int idx, TraceRecord *record)
{
    if (!(trace_buf[idx].event & TRACE_RECORD_VALID)) {
        return false;
    }

    __sync_synchronize(); /* read memory barrier before accessing record */

    *record = trace_buf[idx];
    record->event &= ~TRACE_RECORD_VALID;
    return true;
}

/**
 * Kick writeout thread
 *
 * @wait        Whether to wait for writeout thread to complete
 */
static void flush_trace_file(bool wait)
{
    pthread_mutex_lock(&trace_lock);
    trace_available = true;
    pthread_cond_signal(&trace_available_cond);

    if (wait) {
        pthread_cond_wait(&trace_empty_cond, &trace_lock);
    }

    pthread_mutex_unlock(&trace_lock);
}

static void wait_for_trace_records_available(void)
{
    pthread_mutex_lock(&trace_lock);
    while (!(trace_available && trace_writeout_enabled)) {
        pthread_cond_signal(&trace_empty_cond);
        pthread_cond_wait(&trace_available_cond, &trace_lock);
    }
    trace_available = false;
    pthread_mutex_unlock(&trace_lock);
}

static void *writeout_thread(void *opaque)
{
    TraceRecord record;
    unsigned int writeout_idx = 0;
    unsigned int num_available, idx;
    size_t unused __attribute__ ((unused));

    for (;;) {
        wait_for_trace_records_available();

        num_available = trace_idx - writeout_idx;
        if (num_available > TRACE_BUF_LEN) {
            record = (TraceRecord){
                .event = DROPPED_EVENT_ID,
                .x1 = num_available,
            };
            unused = fwrite(&record, sizeof(record), 1, trace_fp);
            writeout_idx += num_available;
        }

        idx = writeout_idx % TRACE_BUF_LEN;
        while (get_trace_record(idx, &record)) {
            trace_buf[idx].event = 0; /* clear valid bit */
            unused = fwrite(&record, sizeof(record), 1, trace_fp);
            idx = ++writeout_idx % TRACE_BUF_LEN;
        }

        fflush(trace_fp);
    }
    return NULL;
}

static void trace(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3,
                  uint64_t x4, uint64_t x5, uint64_t x6)
{
    unsigned int idx;
    uint64_t timestamp;

    if (!trace_list[event].state) {
        return;
    }

    timestamp = get_clock();

    idx = __sync_fetch_and_add(&trace_idx, 1) % TRACE_BUF_LEN;
    trace_buf[idx] = (TraceRecord){
        .event = event,
        .timestamp_ns = timestamp,
        .x1 = x1,
        .x2 = x2,
        .x3 = x3,
        .x4 = x4,
        .x5 = x5,
        .x6 = x6,
    };
    __sync_synchronize(); /* write barrier before marking as valid */
    trace_buf[idx].event |= TRACE_RECORD_VALID;

    if ((idx + 1) % TRACE_BUF_FLUSH_THRESHOLD == 0) {
        flush_trace_file(false);
    }
}

void trace0(TraceEventID event)
{
    trace(event, 0, 0, 0, 0, 0, 0);
}

void trace1(TraceEventID event, uint64_t x1)
{
    trace(event, x1, 0, 0, 0, 0, 0);
}

void trace2(TraceEventID event, uint64_t x1, uint64_t x2)
{
    trace(event, x1, x2, 0, 0, 0, 0);
}

void trace3(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3)
{
    trace(event, x1, x2, x3, 0, 0, 0);
}

void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4)
{
    trace(event, x1, x2, x3, x4, 0, 0);
}

void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5)
{
    trace(event, x1, x2, x3, x4, x5, 0);
}

void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6)
{
    trace(event, x1, x2, x3, x4, x5, x6);
}

void st_set_trace_file_enabled(bool enable)
{
    if (enable == !!trace_fp) {
        return; /* no change */
    }

    /* Halt trace writeout */
    flush_trace_file(true);
    trace_writeout_enabled = false;
    flush_trace_file(true);

    if (enable) {
        static const TraceRecord header = {
            .event = HEADER_EVENT_ID,
            .timestamp_ns = HEADER_MAGIC,
            .x1 = HEADER_VERSION,
        };

        trace_fp = fopen(trace_file_name, "w");
        if (!trace_fp) {
            return;
        }

        if (fwrite(&header, sizeof header, 1, trace_fp) != 1) {
            fclose(trace_fp);
            trace_fp = NULL;
            return;
        }

        /* Resume trace writeout */
        trace_writeout_enabled = true;
        flush_trace_file(false);
    } else {
        fclose(trace_fp);
        trace_fp = NULL;
    }
}

/**
 * Set the name of a trace file
 *
 * @file        The trace file name or NULL for the default name-<pid> set at
 *              config time
 */
bool st_set_trace_file(const char *file)
{
    st_set_trace_file_enabled(false);

    free(trace_file_name);

    if (!file) {
        if (asprintf(&trace_file_name, CONFIG_TRACE_FILE, getpid()) < 0) {
            trace_file_name = NULL;
            return false;
        }
    } else {
        if (asprintf(&trace_file_name, "%s", file) < 0) {
            trace_file_name = NULL;
            return false;
        }
    }

    st_set_trace_file_enabled(true);
    return true;
}

void st_print_trace_file_status(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
{
    stream_printf(stream, "Trace file \"%s\" %s.\n",
                  trace_file_name, trace_fp ? "on" : "off");
}

void st_print_trace(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
{
    unsigned int i;

    for (i = 0; i < TRACE_BUF_LEN; i++) {
        TraceRecord record;

        if (!get_trace_record(i, &record)) {
            continue;
        }
        stream_printf(stream, "Event %" PRIu64 " : %" PRIx64 " %" PRIx64
                      " %" PRIx64 " %" PRIx64 " %" PRIx64 " %" PRIx64 "\n",
                      record.event, record.x1, record.x2,
                      record.x3, record.x4, record.x5,
                      record.x6);
    }
}

void st_flush_trace_buffer(void)
{
    flush_trace_file(true);
}

void trace_print_events(FILE *stream, fprintf_function stream_printf)
{
    unsigned int i;

    for (i = 0; i < NR_TRACE_EVENTS; i++) {
        stream_printf(stream, "%s [Event ID %u] : state %u\n",
                      trace_list[i].tp_name, i, trace_list[i].state);
    }
}

bool trace_event_set_state(const char *name, bool state)
{
    unsigned int i;

    for (i = 0; i < NR_TRACE_EVENTS; i++) {
        if (!strcmp(trace_list[i].tp_name, name)) {
            trace_list[i].state = state;
            return true;
        }
    }
    return false;
}

bool trace_backend_init(const char *events, const char *file)
{
    pthread_t thread;
    pthread_attr_t attr;
    sigset_t set, oldset;
    int ret;

    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

    sigfillset(&set);
    pthread_sigmask(SIG_SETMASK, &set, &oldset);
    ret = pthread_create(&thread, &attr, writeout_thread, NULL);
    pthread_sigmask(SIG_SETMASK, &oldset, NULL);

    if (ret != 0) {
        fprintf(stderr, "warning: unable to initialize simple trace backend\n");
    } else {
        atexit(st_flush_trace_buffer);
        trace_backend_init_events(events);
        st_set_trace_file(file);
    }

    return true;
}
Commit	Line	Data
26f7227b SH	1	/*
	2	* Simple trace backend
	3	*
	4	* Copyright IBM, Corp. 2010
	5	*
	6	* This work is licensed under the terms of the GNU GPL, version 2. See
	7	* the COPYING file in the top-level directory.
	8	*
	9	*/
	10
	11	#include <stdlib.h>
	12	#include <stdint.h>
	13	#include <stdio.h>
	14	#include <time.h>
0b5538c3 SH	15	#include <signal.h>
0b5538c3 SH	16	#include <pthread.h>
c57c846a	17	#include "qemu-timer.h"
26f7227b	18	#include "trace.h"
e4858974	19	#include "trace/control.h"
26f7227b SH	20
	21	/** Trace file header event ID */
	22	#define HEADER_EVENT_ID (~(uint64_t)0) /* avoids conflicting with TraceEventIDs */
	23
	24	/** Trace file magic number */
	25	#define HEADER_MAGIC 0xf2b177cb0aa429b4ULL
	26
	27	/** Trace file version number, bump if format changes */
	28	#define HEADER_VERSION 0
	29
0b5538c3 SH	30	/** Records were dropped event ID */
	31	#define DROPPED_EVENT_ID (~(uint64_t)0 - 1)
	32
	33	/** Trace record is valid */
	34	#define TRACE_RECORD_VALID ((uint64_t)1 << 63)
	35
26f7227b SH	36	/** Trace buffer entry */
	37	typedef struct {
	38	uint64_t event;
	39	uint64_t timestamp_ns;
	40	uint64_t x1;
	41	uint64_t x2;
	42	uint64_t x3;
	43	uint64_t x4;
	44	uint64_t x5;
	45	uint64_t x6;
	46	} TraceRecord;
	47
	48	enum {
0b5538c3 SH	49	TRACE_BUF_LEN = 4096,
0b5538c3 SH	50	TRACE_BUF_FLUSH_THRESHOLD = TRACE_BUF_LEN / 4,
26f7227b SH	51	};
26f7227b SH	52
0b5538c3 SH	53	/*
	54	* Trace records are written out by a dedicated thread. The thread waits for
	55	* records to become available, writes them out, and then waits again.
	56	*/
	57	static pthread_mutex_t trace_lock = PTHREAD_MUTEX_INITIALIZER;
	58	static pthread_cond_t trace_available_cond = PTHREAD_COND_INITIALIZER;
	59	static pthread_cond_t trace_empty_cond = PTHREAD_COND_INITIALIZER;
	60	static bool trace_available;
	61	static bool trace_writeout_enabled;
	62
26f7227b SH	63	static TraceRecord trace_buf[TRACE_BUF_LEN];
	64	static unsigned int trace_idx;
	65	static FILE *trace_fp;
c5ceb523	66	static char *trace_file_name = NULL;
26f7227b	67
c5ceb523	68	/**
0b5538c3 SH	69	* Read a trace record from the trace buffer
	70	*
	71	* @idx Trace buffer index
	72	* @record Trace record to fill
	73	*
	74	* Returns false if the record is not valid.
c5ceb523	75	*/
0b5538c3	76	static bool get_trace_record(unsigned int idx, TraceRecord *record)
9410b56c	77	{
0b5538c3 SH	78	if (!(trace_buf[idx].event & TRACE_RECORD_VALID)) {
0b5538c3 SH	79	return false;
9410b56c PS	80	}
9410b56c PS	81
0b5538c3 SH	82	__sync_synchronize(); /* read memory barrier before accessing record */
	83
	84	*record = trace_buf[idx];
	85	record->event &= ~TRACE_RECORD_VALID;
c5ceb523	86	return true;
9410b56c PS	87	}
9410b56c PS	88
0b5538c3 SH	89	/**
	90	* Kick writeout thread
	91	*
	92	* @wait Whether to wait for writeout thread to complete
	93	*/
	94	static void flush_trace_file(bool wait)
26f7227b	95	{
0b5538c3 SH	96	pthread_mutex_lock(&trace_lock);
	97	trace_available = true;
	98	pthread_cond_signal(&trace_available_cond);
c5ceb523	99
0b5538c3 SH	100	if (wait) {
0b5538c3 SH	101	pthread_cond_wait(&trace_empty_cond, &trace_lock);
26f7227b	102	}
0b5538c3 SH	103
0b5538c3 SH	104	pthread_mutex_unlock(&trace_lock);
c5ceb523 SH	105	}
c5ceb523 SH	106
0b5538c3	107	static void wait_for_trace_records_available(void)
c5ceb523	108	{
0b5538c3 SH	109	pthread_mutex_lock(&trace_lock);
	110	while (!(trace_available && trace_writeout_enabled)) {
	111	pthread_cond_signal(&trace_empty_cond);
	112	pthread_cond_wait(&trace_available_cond, &trace_lock);
c5ceb523	113	}
0b5538c3 SH	114	trace_available = false;
0b5538c3 SH	115	pthread_mutex_unlock(&trace_lock);
26f7227b SH	116	}
26f7227b SH	117
0b5538c3	118	static void writeout_thread(void opaque)
26f7227b	119	{
0b5538c3 SH	120	TraceRecord record;
	121	unsigned int writeout_idx = 0;
	122	unsigned int num_available, idx;
0caf448b	123	size_t unused __attribute__ ((unused));
0b5538c3 SH	124
	125	for (;;) {
	126	wait_for_trace_records_available();
	127
	128	num_available = trace_idx - writeout_idx;
	129	if (num_available > TRACE_BUF_LEN) {
	130	record = (TraceRecord){
	131	.event = DROPPED_EVENT_ID,
	132	.x1 = num_available,
	133	};
	134	unused = fwrite(&record, sizeof(record), 1, trace_fp);
	135	writeout_idx += num_available;
	136	}
26f7227b	137
0b5538c3 SH	138	idx = writeout_idx % TRACE_BUF_LEN;
	139	while (get_trace_record(idx, &record)) {
	140	trace_buf[idx].event = 0; /* clear valid bit */
	141	unused = fwrite(&record, sizeof(record), 1, trace_fp);
	142	idx = ++writeout_idx % TRACE_BUF_LEN;
	143	}
26f7227b	144
0b5538c3	145	fflush(trace_fp);
26f7227b	146	}
0b5538c3	147	return NULL;
26f7227b SH	148	}
	149
	150	static void trace(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3,
	151	uint64_t x4, uint64_t x5, uint64_t x6)
	152	{
0b5538c3 SH	153	unsigned int idx;
0b5538c3 SH	154	uint64_t timestamp;
26f7227b	155
22890ab5 PS	156	if (!trace_list[event].state) {
	157	return;
	158	}
	159
0b5538c3 SH	160	timestamp = get_clock();
	161
	162	idx = __sync_fetch_and_add(&trace_idx, 1) % TRACE_BUF_LEN;
	163	trace_buf[idx] = (TraceRecord){
	164	.event = event,
	165	.timestamp_ns = timestamp,
	166	.x1 = x1,
	167	.x2 = x2,
	168	.x3 = x3,
	169	.x4 = x4,
	170	.x5 = x5,
	171	.x6 = x6,
	172	};
	173	__sync_synchronize(); /* write barrier before marking as valid */
	174	trace_buf[idx].event \|= TRACE_RECORD_VALID;
	175
	176	if ((idx + 1) % TRACE_BUF_FLUSH_THRESHOLD == 0) {
	177	flush_trace_file(false);
26f7227b SH	178	}
	179	}
	180
	181	void trace0(TraceEventID event)
	182	{
	183	trace(event, 0, 0, 0, 0, 0, 0);
	184	}
	185
	186	void trace1(TraceEventID event, uint64_t x1)
	187	{
	188	trace(event, x1, 0, 0, 0, 0, 0);
	189	}
	190
	191	void trace2(TraceEventID event, uint64_t x1, uint64_t x2)
	192	{
	193	trace(event, x1, x2, 0, 0, 0, 0);
	194	}
	195
	196	void trace3(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3)
	197	{
	198	trace(event, x1, x2, x3, 0, 0, 0);
	199	}
	200
	201	void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4)
	202	{
	203	trace(event, x1, x2, x3, x4, 0, 0);
	204	}
	205
	206	void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5)
	207	{
	208	trace(event, x1, x2, x3, x4, x5, 0);
	209	}
	210
	211	void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6)
	212	{
	213	trace(event, x1, x2, x3, x4, x5, x6);
	214	}
	215
0b5538c3 SH	216	void st_set_trace_file_enabled(bool enable)
	217	{
	218	if (enable == !!trace_fp) {
	219	return; /* no change */
	220	}
	221
	222	/* Halt trace writeout */
	223	flush_trace_file(true);
	224	trace_writeout_enabled = false;
	225	flush_trace_file(true);
	226
	227	if (enable) {
	228	static const TraceRecord header = {
	229	.event = HEADER_EVENT_ID,
	230	.timestamp_ns = HEADER_MAGIC,
	231	.x1 = HEADER_VERSION,
	232	};
	233
	234	trace_fp = fopen(trace_file_name, "w");
	235	if (!trace_fp) {
	236	return;
	237	}
	238
	239	if (fwrite(&header, sizeof header, 1, trace_fp) != 1) {
	240	fclose(trace_fp);
	241	trace_fp = NULL;
	242	return;
	243	}
	244
	245	/* Resume trace writeout */
	246	trace_writeout_enabled = true;
	247	flush_trace_file(false);
	248	} else {
	249	fclose(trace_fp);
	250	trace_fp = NULL;
	251	}
	252	}
	253
26f7227b	254	/**
0b5538c3 SH	255	* Set the name of a trace file
	256	*
	257	* @file The trace file name or NULL for the default name-<pid> set at
	258	* config time
26f7227b	259	*/
0b5538c3	260	bool st_set_trace_file(const char *file)
26f7227b	261	{
0b5538c3 SH	262	st_set_trace_file_enabled(false);
	263
	264	free(trace_file_name);
	265
	266	if (!file) {
	267	if (asprintf(&trace_file_name, CONFIG_TRACE_FILE, getpid()) < 0) {
	268	trace_file_name = NULL;
	269	return false;
	270	}
	271	} else {
	272	if (asprintf(&trace_file_name, "%s", file) < 0) {
	273	trace_file_name = NULL;
	274	return false;
	275	}
	276	}
	277
	278	st_set_trace_file_enabled(true);
	279	return true;
	280	}
	281
	282	void st_print_trace_file_status(FILE stream, int (stream_printf)(FILE stream, const char fmt, ...))
	283	{
	284	stream_printf(stream, "Trace file \"%s\" %s.\n",
	285	trace_file_name, trace_fp ? "on" : "off");
26f7227b	286	}
22890ab5 PS	287
	288	void st_print_trace(FILE stream, int (stream_printf)(FILE stream, const char fmt, ...))
	289	{
	290	unsigned int i;
	291
0b5538c3 SH	292	for (i = 0; i < TRACE_BUF_LEN; i++) {
	293	TraceRecord record;
	294
	295	if (!get_trace_record(i, &record)) {
	296	continue;
	297	}
a12c668f BS	298	stream_printf(stream, "Event %" PRIu64 " : %" PRIx64 " %" PRIx64
a12c668f BS	299	" %" PRIx64 " %" PRIx64 " %" PRIx64 " %" PRIx64 "\n",
0b5538c3 SH	300	record.event, record.x1, record.x2,
	301	record.x3, record.x4, record.x5,
	302	record.x6);
22890ab5 PS	303	}
	304	}
	305
fc764105 L	306	void st_flush_trace_buffer(void)
	307	{
	308	flush_trace_file(true);
	309	}
	310
	311	void trace_print_events(FILE *stream, fprintf_function stream_printf)
22890ab5 PS	312	{
	313	unsigned int i;
	314
	315	for (i = 0; i < NR_TRACE_EVENTS; i++) {
	316	stream_printf(stream, "%s [Event ID %u] : state %u\n",
	317	trace_list[i].tp_name, i, trace_list[i].state);
	318	}
	319	}
	320
fc764105	321	bool trace_event_set_state(const char *name, bool state)
22890ab5 PS	322	{
	323	unsigned int i;
	324
22890ab5	325	for (i = 0; i < NR_TRACE_EVENTS; i++) {
0b5538c3	326	if (!strcmp(trace_list[i].tp_name, name)) {
fc764105	327	trace_list[i].state = state;
0b5538c3	328	return true;
22890ab5 PS	329	}
22890ab5 PS	330	}
0b5538c3 SH	331	return false;
	332	}
	333
23d15e86	334	bool trace_backend_init(const char events, const char file)
22890ab5	335	{
0b5538c3 SH	336	pthread_t thread;
	337	pthread_attr_t attr;
	338	sigset_t set, oldset;
	339	int ret;
	340
	341	pthread_attr_init(&attr);
	342	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
22890ab5	343
0b5538c3 SH	344	sigfillset(&set);
	345	pthread_sigmask(SIG_SETMASK, &set, &oldset);
	346	ret = pthread_create(&thread, &attr, writeout_thread, NULL);
	347	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
	348
	349	if (ret != 0) {
e4858974 L	350	fprintf(stderr, "warning: unable to initialize simple trace backend\n");
	351	} else {
	352	atexit(st_flush_trace_buffer);
23d15e86	353	trace_backend_init_events(events);
e4858974	354	st_set_trace_file(file);
22890ab5	355	}
0b5538c3	356
31d3c9b8	357	return true;
22890ab5	358	}