xref: /illumos-kvm-cmd/simpletrace.c (revision 68396ea9)
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>
15 #include "qemu-timer.h"
16 #include "trace.h"
17 
18 /** Trace file header event ID */
19 #define HEADER_EVENT_ID (~(uint64_t)0) /* avoids conflicting with TraceEventIDs */
20 
21 /** Trace file magic number */
22 #define HEADER_MAGIC 0xf2b177cb0aa429b4ULL
23 
24 /** Trace file version number, bump if format changes */
25 #define HEADER_VERSION 0
26 
27 /** Trace buffer entry */
28 typedef struct {
29     uint64_t event;
30     uint64_t timestamp_ns;
31     uint64_t x1;
32     uint64_t x2;
33     uint64_t x3;
34     uint64_t x4;
35     uint64_t x5;
36     uint64_t x6;
37 } TraceRecord;
38 
39 enum {
40     TRACE_BUF_LEN = 64 * 1024 / sizeof(TraceRecord),
41 };
42 
43 static TraceRecord trace_buf[TRACE_BUF_LEN];
44 static unsigned int trace_idx;
45 static FILE *trace_fp;
46 static char *trace_file_name = NULL;
47 static bool trace_file_enabled = false;
48 
st_print_trace_file_status(FILE * stream,int (* stream_printf)(FILE * stream,const char * fmt,...))49 void st_print_trace_file_status(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
50 {
51     stream_printf(stream, "Trace file \"%s\" %s.\n",
52                   trace_file_name, trace_file_enabled ? "on" : "off");
53 }
54 
write_header(FILE * fp)55 static bool write_header(FILE *fp)
56 {
57     static const TraceRecord header = {
58         .event = HEADER_EVENT_ID,
59         .timestamp_ns = HEADER_MAGIC,
60         .x1 = HEADER_VERSION,
61     };
62 
63     return fwrite(&header, sizeof header, 1, fp) == 1;
64 }
65 
66 /**
67  * set_trace_file : To set the name of a trace file.
68  * @file : pointer to the name to be set.
69  *         If NULL, set to the default name-<pid> set at config time.
70  */
st_set_trace_file(const char * file)71 bool st_set_trace_file(const char *file)
72 {
73     st_set_trace_file_enabled(false);
74 
75     free(trace_file_name);
76 
77     if (!file) {
78         if (asprintf(&trace_file_name, CONFIG_TRACE_FILE, getpid()) < 0) {
79             trace_file_name = NULL;
80             return false;
81         }
82     } else {
83         if (asprintf(&trace_file_name, "%s", file) < 0) {
84             trace_file_name = NULL;
85             return false;
86         }
87     }
88 
89     st_set_trace_file_enabled(true);
90     return true;
91 }
92 
flush_trace_file(void)93 static void flush_trace_file(void)
94 {
95     /* If the trace file is not open yet, open it now */
96     if (!trace_fp) {
97         trace_fp = fopen(trace_file_name, "w");
98         if (!trace_fp) {
99             /* Avoid repeatedly trying to open file on failure */
100             trace_file_enabled = false;
101             return;
102         }
103         write_header(trace_fp);
104     }
105 
106     if (trace_fp) {
107         size_t unused; /* for when fwrite(3) is declared warn_unused_result */
108         unused = fwrite(trace_buf, trace_idx * sizeof(trace_buf[0]), 1, trace_fp);
109     }
110 }
111 
st_flush_trace_buffer(void)112 void st_flush_trace_buffer(void)
113 {
114     if (trace_file_enabled) {
115         flush_trace_file();
116     }
117 
118     /* Discard written trace records */
119     trace_idx = 0;
120 }
121 
st_set_trace_file_enabled(bool enable)122 void st_set_trace_file_enabled(bool enable)
123 {
124     if (enable == trace_file_enabled) {
125         return; /* no change */
126     }
127 
128     /* Flush/discard trace buffer */
129     st_flush_trace_buffer();
130 
131     /* To disable, close trace file */
132     if (!enable) {
133         fclose(trace_fp);
134         trace_fp = NULL;
135     }
136 
137     trace_file_enabled = enable;
138 }
139 
trace(TraceEventID event,uint64_t x1,uint64_t x2,uint64_t x3,uint64_t x4,uint64_t x5,uint64_t x6)140 static void trace(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3,
141                   uint64_t x4, uint64_t x5, uint64_t x6)
142 {
143     TraceRecord *rec = &trace_buf[trace_idx];
144 
145     if (!trace_list[event].state) {
146         return;
147     }
148 
149     rec->event = event;
150     rec->timestamp_ns = get_clock();
151     rec->x1 = x1;
152     rec->x2 = x2;
153     rec->x3 = x3;
154     rec->x4 = x4;
155     rec->x5 = x5;
156     rec->x6 = x6;
157 
158     if (++trace_idx == TRACE_BUF_LEN) {
159         st_flush_trace_buffer();
160     }
161 }
162 
trace0(TraceEventID event)163 void trace0(TraceEventID event)
164 {
165     trace(event, 0, 0, 0, 0, 0, 0);
166 }
167 
trace1(TraceEventID event,uint64_t x1)168 void trace1(TraceEventID event, uint64_t x1)
169 {
170     trace(event, x1, 0, 0, 0, 0, 0);
171 }
172 
trace2(TraceEventID event,uint64_t x1,uint64_t x2)173 void trace2(TraceEventID event, uint64_t x1, uint64_t x2)
174 {
175     trace(event, x1, x2, 0, 0, 0, 0);
176 }
177 
trace3(TraceEventID event,uint64_t x1,uint64_t x2,uint64_t x3)178 void trace3(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3)
179 {
180     trace(event, x1, x2, x3, 0, 0, 0);
181 }
182 
trace4(TraceEventID event,uint64_t x1,uint64_t x2,uint64_t x3,uint64_t x4)183 void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4)
184 {
185     trace(event, x1, x2, x3, x4, 0, 0);
186 }
187 
trace5(TraceEventID event,uint64_t x1,uint64_t x2,uint64_t x3,uint64_t x4,uint64_t x5)188 void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5)
189 {
190     trace(event, x1, x2, x3, x4, x5, 0);
191 }
192 
trace6(TraceEventID event,uint64_t x1,uint64_t x2,uint64_t x3,uint64_t x4,uint64_t x5,uint64_t x6)193 void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6)
194 {
195     trace(event, x1, x2, x3, x4, x5, x6);
196 }
197 
198 /**
199  * Flush the trace buffer on exit
200  */
st_init(void)201 static void __attribute__((constructor)) st_init(void)
202 {
203     atexit(st_flush_trace_buffer);
204 }
205 
st_print_trace(FILE * stream,int (* stream_printf)(FILE * stream,const char * fmt,...))206 void st_print_trace(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
207 {
208     unsigned int i;
209 
210     for (i = 0; i < trace_idx; i++) {
211         stream_printf(stream, "Event %" PRIu64 " : %" PRIx64 " %" PRIx64
212                       " %" PRIx64 " %" PRIx64 " %" PRIx64 " %" PRIx64 "\n",
213                       trace_buf[i].event, trace_buf[i].x1, trace_buf[i].x2,
214                       trace_buf[i].x3, trace_buf[i].x4, trace_buf[i].x5,
215                       trace_buf[i].x6);
216     }
217 }
218 
st_print_trace_events(FILE * stream,int (* stream_printf)(FILE * stream,const char * fmt,...))219 void st_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
220 {
221     unsigned int i;
222 
223     for (i = 0; i < NR_TRACE_EVENTS; i++) {
224         stream_printf(stream, "%s [Event ID %u] : state %u\n",
225                       trace_list[i].tp_name, i, trace_list[i].state);
226     }
227 }
228 
find_trace_event_by_name(const char * tname)229 static TraceEvent* find_trace_event_by_name(const char *tname)
230 {
231     unsigned int i;
232 
233     if (!tname) {
234         return NULL;
235     }
236 
237     for (i = 0; i < NR_TRACE_EVENTS; i++) {
238         if (!strcmp(trace_list[i].tp_name, tname)) {
239             return &trace_list[i];
240         }
241     }
242     return NULL; /* indicates end of list reached without a match */
243 }
244 
st_change_trace_event_state(const char * tname,bool tstate)245 bool st_change_trace_event_state(const char *tname, bool tstate)
246 {
247     TraceEvent *tp;
248 
249     tp = find_trace_event_by_name(tname);
250     if (tp) {
251         tp->state = tstate;
252         return true;
253     }
254     return false;
255 }
256