virtio/virtio-trace/trace-agent.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Guest agent for virtio-trace
0004  *
0005  * Copyright (C) 2012 Hitachi, Ltd.
0006  * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
0007  *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
0008  */
0009
0010 #define _GNU_SOURCE
0011 #include <limits.h>
0012 #include <stdio.h>
0013 #include <stdlib.h>
0014 #include <unistd.h>
0015 #include "trace-agent.h"
0016
0017 #define PAGE_SIZE       (sysconf(_SC_PAGE_SIZE))
0018 #define PIPE_DEF_BUFS       16
0019 #define PIPE_MIN_SIZE       (PAGE_SIZE*PIPE_DEF_BUFS)
0020 #define PIPE_MAX_SIZE       (1024*1024)
0021 #define READ_PATH_FMT   \
0022         "/sys/kernel/debug/tracing/per_cpu/cpu%d/trace_pipe_raw"
0023 #define WRITE_PATH_FMT      "/dev/virtio-ports/trace-path-cpu%d"
0024 #define CTL_PATH        "/dev/virtio-ports/agent-ctl-path"
0025
0026 pthread_mutex_t mutex_notify = PTHREAD_MUTEX_INITIALIZER;
0027 pthread_cond_t cond_wakeup = PTHREAD_COND_INITIALIZER;
0028
0029 static int get_total_cpus(void)
0030 {
0031     int nr_cpus = (int)sysconf(_SC_NPROCESSORS_CONF);
0032
0033     if (nr_cpus <= 0) {
0034         pr_err("Could not read cpus\n");
0035         goto error;
0036     } else if (nr_cpus > MAX_CPUS) {
0037         pr_err("Exceed max cpus(%d)\n", (int)MAX_CPUS);
0038         goto error;
0039     }
0040
0041     return nr_cpus;
0042
0043 error:
0044     exit(EXIT_FAILURE);
0045 }
0046
0047 static void *agent_info_new(void)
0048 {
0049     struct agent_info *s;
0050     int i;
0051
0052     s = zalloc(sizeof(struct agent_info));
0053     if (s == NULL) {
0054         pr_err("agent_info zalloc error\n");
0055         exit(EXIT_FAILURE);
0056     }
0057
0058     s->pipe_size = PIPE_INIT;
0059     s->use_stdout = false;
0060     s->cpus = get_total_cpus();
0061     s->ctl_fd = -1;
0062
0063     /* read/write threads init */
0064     for (i = 0; i < s->cpus; i++)
0065         s->rw_ti[i] = rw_thread_info_new();
0066
0067     return s;
0068 }
0069
0070 static unsigned long parse_size(const char *arg)
0071 {
0072     unsigned long value, round;
0073     char *ptr;
0074
0075     value = strtoul(arg, &ptr, 10);
0076     switch (*ptr) {
0077     case 'K': case 'k':
0078         value <<= 10;
0079         break;
0080     case 'M': case 'm':
0081         value <<= 20;
0082         break;
0083     default:
0084         break;
0085     }
0086
0087     if (value > PIPE_MAX_SIZE) {
0088         pr_err("Pipe size must be less than 1MB\n");
0089         goto error;
0090     } else if (value < PIPE_MIN_SIZE) {
0091         pr_err("Pipe size must be over 64KB\n");
0092         goto error;
0093     }
0094
0095     /* Align buffer size with page unit */
0096     round = value & (PAGE_SIZE - 1);
0097     value = value - round;
0098
0099     return value;
0100 error:
0101     return 0;
0102 }
0103
0104 static void usage(char const *prg)
0105 {
0106     pr_err("usage: %s [-h] [-o] [-s <size of pipe>]\n", prg);
0107 }
0108
0109 static const char *make_path(int cpu_num, bool this_is_write_path)
0110 {
0111     int ret;
0112     char *buf;
0113
0114     buf = zalloc(PATH_MAX);
0115     if (buf == NULL) {
0116         pr_err("Could not allocate buffer\n");
0117         goto error;
0118     }
0119
0120     if (this_is_write_path)
0121         /* write(output) path */
0122         ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num);
0123     else
0124         /* read(input) path */
0125         ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, cpu_num);
0126
0127     if (ret <= 0) {
0128         pr_err("Failed to generate %s path(CPU#%d):%d\n",
0129             this_is_write_path ? "read" : "write", cpu_num, ret);
0130         goto error;
0131     }
0132
0133     return buf;
0134
0135 error:
0136     free(buf);
0137     return NULL;
0138 }
0139
0140 static const char *make_input_path(int cpu_num)
0141 {
0142     return make_path(cpu_num, false);
0143 }
0144
0145 static const char *make_output_path(int cpu_num)
0146 {
0147     return make_path(cpu_num, true);
0148 }
0149
0150 static void *agent_info_init(struct agent_info *s)
0151 {
0152     int cpu;
0153     const char *in_path = NULL;
0154     const char *out_path = NULL;
0155
0156     /* init read/write threads */
0157     for (cpu = 0; cpu < s->cpus; cpu++) {
0158         /* set read(input) path per read/write thread */
0159         in_path = make_input_path(cpu);
0160         if (in_path == NULL)
0161             goto error;
0162
0163         /* set write(output) path per read/write thread*/
0164         if (!s->use_stdout) {
0165             out_path = make_output_path(cpu);
0166             if (out_path == NULL)
0167                 goto error;
0168         } else
0169             /* stdout mode */
0170             pr_debug("stdout mode\n");
0171
0172         rw_thread_init(cpu, in_path, out_path, s->use_stdout,
0173                         s->pipe_size, s->rw_ti[cpu]);
0174     }
0175
0176     /* init controller of read/write threads */
0177     s->ctl_fd = rw_ctl_init((const char *)CTL_PATH);
0178
0179     return NULL;
0180
0181 error:
0182     exit(EXIT_FAILURE);
0183 }
0184
0185 static void *parse_args(int argc, char *argv[], struct agent_info *s)
0186 {
0187     int cmd;
0188     unsigned long size;
0189
0190     while ((cmd = getopt(argc, argv, "hos:")) != -1) {
0191         switch (cmd) {
0192         /* stdout mode */
0193         case 'o':
0194             s->use_stdout = true;
0195             break;
0196         /* size of pipe */
0197         case 's':
0198             size = parse_size(optarg);
0199             if (size == 0)
0200                 goto error;
0201             s->pipe_size = size;
0202             break;
0203         case 'h':
0204         default:
0205             usage(argv[0]);
0206             goto error;
0207         }
0208     }
0209
0210     agent_info_init(s);
0211
0212     return NULL;
0213
0214 error:
0215     exit(EXIT_FAILURE);
0216 }
0217
0218 static void agent_main_loop(struct agent_info *s)
0219 {
0220     int cpu;
0221     pthread_t rw_thread_per_cpu[MAX_CPUS];
0222
0223     /* Start all read/write threads */
0224     for (cpu = 0; cpu < s->cpus; cpu++)
0225         rw_thread_per_cpu[cpu] = rw_thread_run(s->rw_ti[cpu]);
0226
0227     rw_ctl_loop(s->ctl_fd);
0228
0229     /* Finish all read/write threads */
0230     for (cpu = 0; cpu < s->cpus; cpu++) {
0231         int ret;
0232
0233         ret = pthread_join(rw_thread_per_cpu[cpu], NULL);
0234         if (ret != 0) {
0235             pr_err("pthread_join() error:%d (cpu %d)\n", ret, cpu);
0236             exit(EXIT_FAILURE);
0237         }
0238     }
0239 }
0240
0241 static void agent_info_free(struct agent_info *s)
0242 {
0243     int i;
0244
0245     close(s->ctl_fd);
0246     for (i = 0; i < s->cpus; i++) {
0247         close(s->rw_ti[i]->in_fd);
0248         close(s->rw_ti[i]->out_fd);
0249         close(s->rw_ti[i]->read_pipe);
0250         close(s->rw_ti[i]->write_pipe);
0251         free(s->rw_ti[i]);
0252     }
0253     free(s);
0254 }
0255
0256 int main(int argc, char *argv[])
0257 {
0258     struct agent_info *s = NULL;
0259
0260     s = agent_info_new();
0261     parse_args(argc, argv, s);
0262
0263     agent_main_loop(s);
0264
0265     agent_info_free(s);
0266
0267     return 0;
0268 }