simpletrace.c - qemu - Git at Google

 /*
  * 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 __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_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;
 }
	/*
	* 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 __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_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;
	}