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