torvalds/linux

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Guest agent for virtio-trace
 *
 * Copyright (C) 2012 Hitachi, Ltd.
 * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
 *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
 */

#define _GNU_SOURCE
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "trace-agent.h"

#define PAGE_SIZE        (sysconf(_SC_PAGE_SIZE))
#define PIPE_DEF_BUFS        16
#define PIPE_MIN_SIZE        (PAGE_SIZE*PIPE_DEF_BUFS)
#define PIPE_MAX_SIZE        (1024*1024)
#define TRACEFS         "/sys/kernel/tracing"
#define DEBUGFS         "/sys/kernel/debug/tracing"
#define READ_PATH_FMT        "%s/per_cpu/cpu%d/trace_pipe_raw"
#define WRITE_PATH_FMT        "/dev/virtio-ports/trace-path-cpu%d"
#define CTL_PATH        "/dev/virtio-ports/agent-ctl-path"

pthread_mutex_t mutex_notify = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond_wakeup = PTHREAD_COND_INITIALIZER;

static int get_total_cpus(void)
{
    int nr_cpus = (int)sysconf(_SC_NPROCESSORS_CONF);

    if (nr_cpus <= 0) {
        pr_err("Could not read cpus\n");
        goto error;
    } else if (nr_cpus > MAX_CPUS) {
        pr_err("Exceed max cpus(%d)\n", (int)MAX_CPUS);
        goto error;
    }

    return nr_cpus;

error:
    exit(EXIT_FAILURE);
}

static void *agent_info_new(void)
{
    struct agent_info *s;
    int i;

    s = zalloc(sizeof(struct agent_info));
    if (s == NULL) {
        pr_err("agent_info zalloc error\n");
        exit(EXIT_FAILURE);
    }

    s->pipe_size = PIPE_INIT;
    s->use_stdout = false;
    s->cpus = get_total_cpus();
    s->ctl_fd = -1;

    /* read/write threads init */
    for (i = 0; i < s->cpus; i++)
        s->rw_ti[i] = rw_thread_info_new();

    return s;
}

static unsigned long parse_size(const char *arg)
{
    unsigned long value, round;
    char *ptr;

    value = strtoul(arg, &ptr, 10);
    switch (*ptr) {
    case 'K': case 'k':
        value <<= 10;
        break;
    case 'M': case 'm':
        value <<= 20;
        break;
    default:
        break;
    }

    if (value > PIPE_MAX_SIZE) {
        pr_err("Pipe size must be less than 1MB\n");
        goto error;
    } else if (value < PIPE_MIN_SIZE) {
        pr_err("Pipe size must be over 64KB\n");
        goto error;
    }

    /* Align buffer size with page unit */
    round = value & (PAGE_SIZE - 1);
    value = value - round;

    return value;
error:
    return 0;
}

static void usage(char const *prg)
{
    pr_err("usage: %s [-h] [-o] [-s <size of pipe>]\n", prg);
}

static const char *make_path(int cpu_num, bool this_is_write_path)
{
    int ret;
    char *buf;

    buf = zalloc(PATH_MAX);
    if (buf == NULL) {
        pr_err("Could not allocate buffer\n");
        goto error;
    }

    if (this_is_write_path)
        /* write(output) path */
        ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num);
    else {
        /* read(input) path */
        ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, TRACEFS, cpu_num);
        if (ret > 0 && access(buf, F_OK) != 0)
            ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, DEBUGFS, cpu_num);
    }

    if (ret <= 0) {
        pr_err("Failed to generate %s path(CPU#%d):%d\n",
            this_is_write_path ? "read" : "write", cpu_num, ret);
        goto error;
    }

    return buf;

error:
    free(buf);
    return NULL;
}

static const char *make_input_path(int cpu_num)
{
    return make_path(cpu_num, false);
}

static const char *make_output_path(int cpu_num)
{
    return make_path(cpu_num, true);
}

static void *agent_info_init(struct agent_info *s)
{
    int cpu;
    const char *in_path = NULL;
    const char *out_path = NULL;

    /* init read/write threads */
    for (cpu = 0; cpu < s->cpus; cpu++) {
        /* set read(input) path per read/write thread */
        in_path = make_input_path(cpu);
        if (in_path == NULL)
            goto error;

        /* set write(output) path per read/write thread*/
        if (!s->use_stdout) {
            out_path = make_output_path(cpu);
            if (out_path == NULL)
                goto error;
        } else
            /* stdout mode */
            pr_debug("stdout mode\n");

        rw_thread_init(cpu, in_path, out_path, s->use_stdout,
                        s->pipe_size, s->rw_ti[cpu]);
    }

    /* init controller of read/write threads */
    s->ctl_fd = rw_ctl_init((const char *)CTL_PATH);

    return NULL;

error:
    exit(EXIT_FAILURE);
}

static void *parse_args(int argc, char *argv[], struct agent_info *s)
{
    int cmd;
    unsigned long size;

    while ((cmd = getopt(argc, argv, "hos:")) != -1) {
        switch (cmd) {
        /* stdout mode */
        case 'o':
            s->use_stdout = true;
            break;
        /* size of pipe */
        case 's':
            size = parse_size(optarg);
            if (size == 0)
                goto error;
            s->pipe_size = size;
            break;
        case 'h':
        default:
            usage(argv[0]);
            goto error;
        }
    }

    agent_info_init(s);

    return NULL;

error:
    exit(EXIT_FAILURE);
}

static void agent_main_loop(struct agent_info *s)
{
    int cpu;
    pthread_t rw_thread_per_cpu[MAX_CPUS];

    /* Start all read/write threads */
    for (cpu = 0; cpu < s->cpus; cpu++)
        rw_thread_per_cpu[cpu] = rw_thread_run(s->rw_ti[cpu]);

    rw_ctl_loop(s->ctl_fd);

    /* Finish all read/write threads */
    for (cpu = 0; cpu < s->cpus; cpu++) {
        int ret;

        ret = pthread_join(rw_thread_per_cpu[cpu], NULL);
        if (ret != 0) {
            pr_err("pthread_join() error:%d (cpu %d)\n", ret, cpu);
            exit(EXIT_FAILURE);
        }
    }
}

static void agent_info_free(struct agent_info *s)
{
    int i;

    close(s->ctl_fd);
    for (i = 0; i < s->cpus; i++) {
        close(s->rw_ti[i]->in_fd);
        close(s->rw_ti[i]->out_fd);
        close(s->rw_ti[i]->read_pipe);
        close(s->rw_ti[i]->write_pipe);
        free(s->rw_ti[i]);
    }
    free(s);
}

int main(int argc, char *argv[])
{
    struct agent_info *s = NULL;

    s = agent_info_new();
    parse_args(argc, argv, s);

    agent_main_loop(s);

    agent_info_free(s);

    return 0;
}