// 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;
}