cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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trace-agent-ctl.c (2673B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Controller of read/write threads 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 <fcntl.h>
     12#include <poll.h>
     13#include <signal.h>
     14#include <stdio.h>
     15#include <stdlib.h>
     16#include <unistd.h>
     17#include "trace-agent.h"
     18
     19#define HOST_MSG_SIZE		256
     20#define EVENT_WAIT_MSEC		100
     21
     22static volatile sig_atomic_t global_signal_val;
     23bool global_sig_receive;	/* default false */
     24bool global_run_operation;	/* default false*/
     25
     26/* Handle SIGTERM/SIGINT/SIGQUIT to exit */
     27static void signal_handler(int sig)
     28{
     29	global_signal_val = sig;
     30}
     31
     32int rw_ctl_init(const char *ctl_path)
     33{
     34	int ctl_fd;
     35
     36	ctl_fd = open(ctl_path, O_RDONLY);
     37	if (ctl_fd == -1) {
     38		pr_err("Cannot open ctl_fd\n");
     39		goto error;
     40	}
     41
     42	return ctl_fd;
     43
     44error:
     45	exit(EXIT_FAILURE);
     46}
     47
     48static int wait_order(int ctl_fd)
     49{
     50	struct pollfd poll_fd;
     51	int ret = 0;
     52
     53	while (!global_sig_receive) {
     54		poll_fd.fd = ctl_fd;
     55		poll_fd.events = POLLIN;
     56
     57		ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC);
     58
     59		if (global_signal_val) {
     60			global_sig_receive = true;
     61			pr_info("Receive interrupt %d\n", global_signal_val);
     62
     63			/* Wakes rw-threads when they are sleeping */
     64			if (!global_run_operation)
     65				pthread_cond_broadcast(&cond_wakeup);
     66
     67			ret = -1;
     68			break;
     69		}
     70
     71		if (ret < 0) {
     72			pr_err("Polling error\n");
     73			goto error;
     74		}
     75
     76		if (ret)
     77			break;
     78	};
     79
     80	return ret;
     81
     82error:
     83	exit(EXIT_FAILURE);
     84}
     85
     86/*
     87 * contol read/write threads by handling global_run_operation
     88 */
     89void *rw_ctl_loop(int ctl_fd)
     90{
     91	ssize_t rlen;
     92	char buf[HOST_MSG_SIZE];
     93	int ret;
     94
     95	/* Setup signal handlers */
     96	signal(SIGTERM, signal_handler);
     97	signal(SIGINT, signal_handler);
     98	signal(SIGQUIT, signal_handler);
     99
    100	while (!global_sig_receive) {
    101
    102		ret = wait_order(ctl_fd);
    103		if (ret < 0)
    104			break;
    105
    106		rlen = read(ctl_fd, buf, sizeof(buf));
    107		if (rlen < 0) {
    108			pr_err("read data error in ctl thread\n");
    109			goto error;
    110		}
    111
    112		if (rlen == 2 && buf[0] == '1') {
    113			/*
    114			 * If host writes '1' to a control path,
    115			 * this controller wakes all read/write threads.
    116			 */
    117			global_run_operation = true;
    118			pthread_cond_broadcast(&cond_wakeup);
    119			pr_debug("Wake up all read/write threads\n");
    120		} else if (rlen == 2 && buf[0] == '0') {
    121			/*
    122			 * If host writes '0' to a control path, read/write
    123			 * threads will wait for notification from Host.
    124			 */
    125			global_run_operation = false;
    126			pr_debug("Stop all read/write threads\n");
    127		} else
    128			pr_info("Invalid host notification: %s\n", buf);
    129	}
    130
    131	return NULL;
    132
    133error:
    134	exit(EXIT_FAILURE);
    135}