xref: /linux/tools/virtio/virtio-trace/trace-agent.c (revision 1ac731c529cd4d6adbce134754b51ff7d822b145)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Guest agent for virtio-trace
4  *
5  * Copyright (C) 2012 Hitachi, Ltd.
6  * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
7  *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
8  */
9 
10 #define _GNU_SOURCE
11 #include <limits.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <unistd.h>
15 #include "trace-agent.h"
16 
17 #define PAGE_SIZE		(sysconf(_SC_PAGE_SIZE))
18 #define PIPE_DEF_BUFS		16
19 #define PIPE_MIN_SIZE		(PAGE_SIZE*PIPE_DEF_BUFS)
20 #define PIPE_MAX_SIZE		(1024*1024)
21 #define TRACEFS 		"/sys/kernel/tracing"
22 #define DEBUGFS 		"/sys/kernel/debug/tracing"
23 #define READ_PATH_FMT		"%s/per_cpu/cpu%d/trace_pipe_raw"
24 #define WRITE_PATH_FMT		"/dev/virtio-ports/trace-path-cpu%d"
25 #define CTL_PATH		"/dev/virtio-ports/agent-ctl-path"
26 
27 pthread_mutex_t mutex_notify = PTHREAD_MUTEX_INITIALIZER;
28 pthread_cond_t cond_wakeup = PTHREAD_COND_INITIALIZER;
29 
get_total_cpus(void)30 static int get_total_cpus(void)
31 {
32 	int nr_cpus = (int)sysconf(_SC_NPROCESSORS_CONF);
33 
34 	if (nr_cpus <= 0) {
35 		pr_err("Could not read cpus\n");
36 		goto error;
37 	} else if (nr_cpus > MAX_CPUS) {
38 		pr_err("Exceed max cpus(%d)\n", (int)MAX_CPUS);
39 		goto error;
40 	}
41 
42 	return nr_cpus;
43 
44 error:
45 	exit(EXIT_FAILURE);
46 }
47 
agent_info_new(void)48 static void *agent_info_new(void)
49 {
50 	struct agent_info *s;
51 	int i;
52 
53 	s = zalloc(sizeof(struct agent_info));
54 	if (s == NULL) {
55 		pr_err("agent_info zalloc error\n");
56 		exit(EXIT_FAILURE);
57 	}
58 
59 	s->pipe_size = PIPE_INIT;
60 	s->use_stdout = false;
61 	s->cpus = get_total_cpus();
62 	s->ctl_fd = -1;
63 
64 	/* read/write threads init */
65 	for (i = 0; i < s->cpus; i++)
66 		s->rw_ti[i] = rw_thread_info_new();
67 
68 	return s;
69 }
70 
parse_size(const char * arg)71 static unsigned long parse_size(const char *arg)
72 {
73 	unsigned long value, round;
74 	char *ptr;
75 
76 	value = strtoul(arg, &ptr, 10);
77 	switch (*ptr) {
78 	case 'K': case 'k':
79 		value <<= 10;
80 		break;
81 	case 'M': case 'm':
82 		value <<= 20;
83 		break;
84 	default:
85 		break;
86 	}
87 
88 	if (value > PIPE_MAX_SIZE) {
89 		pr_err("Pipe size must be less than 1MB\n");
90 		goto error;
91 	} else if (value < PIPE_MIN_SIZE) {
92 		pr_err("Pipe size must be over 64KB\n");
93 		goto error;
94 	}
95 
96 	/* Align buffer size with page unit */
97 	round = value & (PAGE_SIZE - 1);
98 	value = value - round;
99 
100 	return value;
101 error:
102 	return 0;
103 }
104 
usage(char const * prg)105 static void usage(char const *prg)
106 {
107 	pr_err("usage: %s [-h] [-o] [-s <size of pipe>]\n", prg);
108 }
109 
make_path(int cpu_num,bool this_is_write_path)110 static const char *make_path(int cpu_num, bool this_is_write_path)
111 {
112 	int ret;
113 	char *buf;
114 
115 	buf = zalloc(PATH_MAX);
116 	if (buf == NULL) {
117 		pr_err("Could not allocate buffer\n");
118 		goto error;
119 	}
120 
121 	if (this_is_write_path)
122 		/* write(output) path */
123 		ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num);
124 	else {
125 		/* read(input) path */
126 		ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, TRACEFS, cpu_num);
127 		if (ret > 0 && access(buf, F_OK) != 0)
128 			ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, DEBUGFS, cpu_num);
129 	}
130 
131 	if (ret <= 0) {
132 		pr_err("Failed to generate %s path(CPU#%d):%d\n",
133 			this_is_write_path ? "read" : "write", cpu_num, ret);
134 		goto error;
135 	}
136 
137 	return buf;
138 
139 error:
140 	free(buf);
141 	return NULL;
142 }
143 
make_input_path(int cpu_num)144 static const char *make_input_path(int cpu_num)
145 {
146 	return make_path(cpu_num, false);
147 }
148 
make_output_path(int cpu_num)149 static const char *make_output_path(int cpu_num)
150 {
151 	return make_path(cpu_num, true);
152 }
153 
agent_info_init(struct agent_info * s)154 static void *agent_info_init(struct agent_info *s)
155 {
156 	int cpu;
157 	const char *in_path = NULL;
158 	const char *out_path = NULL;
159 
160 	/* init read/write threads */
161 	for (cpu = 0; cpu < s->cpus; cpu++) {
162 		/* set read(input) path per read/write thread */
163 		in_path = make_input_path(cpu);
164 		if (in_path == NULL)
165 			goto error;
166 
167 		/* set write(output) path per read/write thread*/
168 		if (!s->use_stdout) {
169 			out_path = make_output_path(cpu);
170 			if (out_path == NULL)
171 				goto error;
172 		} else
173 			/* stdout mode */
174 			pr_debug("stdout mode\n");
175 
176 		rw_thread_init(cpu, in_path, out_path, s->use_stdout,
177 						s->pipe_size, s->rw_ti[cpu]);
178 	}
179 
180 	/* init controller of read/write threads */
181 	s->ctl_fd = rw_ctl_init((const char *)CTL_PATH);
182 
183 	return NULL;
184 
185 error:
186 	exit(EXIT_FAILURE);
187 }
188 
parse_args(int argc,char * argv[],struct agent_info * s)189 static void *parse_args(int argc, char *argv[], struct agent_info *s)
190 {
191 	int cmd;
192 	unsigned long size;
193 
194 	while ((cmd = getopt(argc, argv, "hos:")) != -1) {
195 		switch (cmd) {
196 		/* stdout mode */
197 		case 'o':
198 			s->use_stdout = true;
199 			break;
200 		/* size of pipe */
201 		case 's':
202 			size = parse_size(optarg);
203 			if (size == 0)
204 				goto error;
205 			s->pipe_size = size;
206 			break;
207 		case 'h':
208 		default:
209 			usage(argv[0]);
210 			goto error;
211 		}
212 	}
213 
214 	agent_info_init(s);
215 
216 	return NULL;
217 
218 error:
219 	exit(EXIT_FAILURE);
220 }
221 
agent_main_loop(struct agent_info * s)222 static void agent_main_loop(struct agent_info *s)
223 {
224 	int cpu;
225 	pthread_t rw_thread_per_cpu[MAX_CPUS];
226 
227 	/* Start all read/write threads */
228 	for (cpu = 0; cpu < s->cpus; cpu++)
229 		rw_thread_per_cpu[cpu] = rw_thread_run(s->rw_ti[cpu]);
230 
231 	rw_ctl_loop(s->ctl_fd);
232 
233 	/* Finish all read/write threads */
234 	for (cpu = 0; cpu < s->cpus; cpu++) {
235 		int ret;
236 
237 		ret = pthread_join(rw_thread_per_cpu[cpu], NULL);
238 		if (ret != 0) {
239 			pr_err("pthread_join() error:%d (cpu %d)\n", ret, cpu);
240 			exit(EXIT_FAILURE);
241 		}
242 	}
243 }
244 
agent_info_free(struct agent_info * s)245 static void agent_info_free(struct agent_info *s)
246 {
247 	int i;
248 
249 	close(s->ctl_fd);
250 	for (i = 0; i < s->cpus; i++) {
251 		close(s->rw_ti[i]->in_fd);
252 		close(s->rw_ti[i]->out_fd);
253 		close(s->rw_ti[i]->read_pipe);
254 		close(s->rw_ti[i]->write_pipe);
255 		free(s->rw_ti[i]);
256 	}
257 	free(s);
258 }
259 
main(int argc,char * argv[])260 int main(int argc, char *argv[])
261 {
262 	struct agent_info *s = NULL;
263 
264 	s = agent_info_new();
265 	parse_args(argc, argv, s);
266 
267 	agent_main_loop(s);
268 
269 	agent_info_free(s);
270 
271 	return 0;
272 }
273