[qemu.git] / simpletrace.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"

/** 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;

    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_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
{
    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 st_change_trace_event_state(const char *name, bool enabled)
{
    unsigned int i;

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

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

bool st_init(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) {
        return false;
    }

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