// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE

#include <errno.h>
#include <fcntl.h>
#include <linux/perf_event.h>
#include <stddef.h>
#include <sched.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/wait.h>
#include <unistd.h>

#include "kselftest_harness.h"

static int sigio_count;

static void handle_sigio(int signum __maybe_unused,
                         siginfo_t *oh __maybe_unused,
                         void *uc __maybe_unused)
{
        ++sigio_count;
}

static void do_child(void)
{
        raise(SIGSTOP);

        for (int i = 0; i < 20; ++i)
                sleep(1);

        raise(SIGSTOP);

        exit(0);
}

TEST(watermark_signal)
{
        struct perf_event_attr attr;
        struct perf_event_mmap_page *p = NULL;
        struct sigaction previous_sigio, sigio = { 0 };
        pid_t child = -1;
        int child_status;
        int fd = -1;
        long page_size = sysconf(_SC_PAGE_SIZE);

        sigio.sa_sigaction = handle_sigio;
        EXPECT_EQ(sigaction(SIGIO, &sigio, &previous_sigio), 0);

        memset(&attr, 0, sizeof(attr));
        attr.size = sizeof(attr);
        attr.type = PERF_TYPE_SOFTWARE;
        attr.config = PERF_COUNT_SW_DUMMY;
        attr.sample_period = 1;
        attr.disabled = 1;
        attr.watermark = 1;
        attr.context_switch = 1;
        attr.wakeup_watermark = 1;

        child = fork();
        EXPECT_GE(child, 0);
        if (child == 0)
                do_child();
        else if (child < 0) {
                perror("fork()");
                goto cleanup;
        }

        if (waitpid(child, &child_status, WSTOPPED) != child ||
            !(WIFSTOPPED(child_status) && WSTOPSIG(child_status) == SIGSTOP)) {
                fprintf(stderr,
                        "failed to synchronize with child errno=%d status=%x\n",
                        errno,
                        child_status);
                goto cleanup;
        }

        fd = syscall(__NR_perf_event_open, &attr, child, -1, -1,
                     PERF_FLAG_FD_CLOEXEC);
        if (fd < 0) {
                fprintf(stderr, "failed opening event %llx\n", attr.config);
                goto cleanup;
        }

        if (fcntl(fd, F_SETFL, FASYNC)) {
                perror("F_SETFL FASYNC");
                goto cleanup;
        }

        if (fcntl(fd, F_SETOWN, getpid())) {
                perror("F_SETOWN getpid()");
                goto cleanup;
        }

        if (fcntl(fd, F_SETSIG, SIGIO)) {
                perror("F_SETSIG SIGIO");
                goto cleanup;
        }

        p = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (p == NULL) {
                perror("mmap");
                goto cleanup;
        }

        if (ioctl(fd, PERF_EVENT_IOC_ENABLE, 0)) {
                perror("PERF_EVENT_IOC_ENABLE");
                goto cleanup;
        }

        if (kill(child, SIGCONT) < 0) {
                perror("SIGCONT");
                goto cleanup;
        }

        if (waitpid(child, &child_status, WSTOPPED) != -1 || errno != EINTR)
                fprintf(stderr,
                        "expected SIGIO to terminate wait errno=%d status=%x\n%d",
                        errno,
                        child_status,
                        sigio_count);

        EXPECT_GE(sigio_count, 1);

cleanup:
        if (p != NULL)
                munmap(p, 2 * page_size);

        if (fd >= 0)
                close(fd);

        if (child > 0) {
                kill(child, SIGKILL);
                waitpid(child, NULL, 0);
        }

        sigaction(SIGIO, &previous_sigio, NULL);
}

TEST_HARNESS_MAIN