// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include <sys/time.h>
#include <sys/resource.h>
#include "test_send_signal_kern.skel.h"
#include "io_helpers.h"

static int sigusr1_received;

static void sigusr1_handler(int signum)
{
        sigusr1_received = 8;
}

static void sigusr1_siginfo_handler(int s, siginfo_t *i, void *v)
{
        sigusr1_received = (int)(long long)i->si_value.sival_ptr;
}

static void test_send_signal_common(struct perf_event_attr *attr,
                                    bool signal_thread, bool remote)
{
        struct test_send_signal_kern *skel;
        struct sigaction sa;
        int pipe_c2p[2], pipe_p2c[2];
        int err = -1, pmu_fd = -1;
        volatile int j = 0;
        int retry_count;
        char buf[256];
        pid_t pid;
        int old_prio;

        if (!ASSERT_OK(pipe(pipe_c2p), "pipe_c2p"))
                return;

        if (!ASSERT_OK(pipe(pipe_p2c), "pipe_p2c")) {
                close(pipe_c2p[0]);
                close(pipe_c2p[1]);
                return;
        }

        pid = fork();
        if (!ASSERT_GE(pid, 0, "fork")) {
                close(pipe_c2p[0]);
                close(pipe_c2p[1]);
                close(pipe_p2c[0]);
                close(pipe_p2c[1]);
                return;
        }

        if (pid == 0) {
                /* install signal handler and notify parent */
                if (remote) {
                        sa.sa_sigaction = sigusr1_siginfo_handler;
                        sa.sa_flags = SA_RESTART | SA_SIGINFO;
                        ASSERT_NEQ(sigaction(SIGUSR1, &sa, NULL), -1, "sigaction");
                } else {
                        ASSERT_NEQ(signal(SIGUSR1, sigusr1_handler), SIG_ERR, "signal");
                }

                close(pipe_c2p[0]); /* close read */
                close(pipe_p2c[1]); /* close write */

                /* boost with a high priority so we got a higher chance
                 * that if an interrupt happens, the underlying task
                 * is this process.
                 */
                if (!remote) {
                        errno = 0;
                        old_prio = getpriority(PRIO_PROCESS, 0);
                        ASSERT_OK(errno, "getpriority");
                        ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority");
                }

                /* notify parent signal handler is installed */
                ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");

                /* make sure parent enabled bpf program to send_signal */
                ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");

                /* wait a little for signal handler */
                for (int i = 0; i < 1000000000 && !sigusr1_received; i++) {
                        j /= i + j + 1;
                        if (remote)
                                sleep(1);
                        else
                                if (!attr)
                                        /* trigger the nanosleep tracepoint program. */
                                        usleep(1);
                }

                buf[0] = sigusr1_received;

                ASSERT_EQ(sigusr1_received, 8, "sigusr1_received");
                ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");

                /* wait for parent notification and exit */
                ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");

                /* restore the old priority */
                if (!remote)
                        ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority");

                close(pipe_c2p[1]);
                close(pipe_p2c[0]);
                exit(0);
        }

        close(pipe_c2p[1]); /* close write */
        close(pipe_p2c[0]); /* close read */

        skel = test_send_signal_kern__open_and_load();
        if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
                goto skel_open_load_failure;

        /* boost with a high priority so we got a higher chance
         * that if an interrupt happens, the underlying task
         * is this process.
         */
        if (remote) {
                errno = 0;
                old_prio = getpriority(PRIO_PROCESS, 0);
                ASSERT_OK(errno, "getpriority");
                ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority");
        }

        if (!attr) {
                err = test_send_signal_kern__attach(skel);
                if (!ASSERT_OK(err, "skel_attach")) {
                        err = -1;
                        goto destroy_skel;
                }
        } else {
                if (!remote)
                        pmu_fd = syscall(__NR_perf_event_open, attr, pid, -1 /* cpu */,
                                         -1 /* group id */, 0 /* flags */);
                else
                        pmu_fd = syscall(__NR_perf_event_open, attr, getpid(), -1 /* cpu */,
                                         -1 /* group id */, 0 /* flags */);
                if (!ASSERT_GE(pmu_fd, 0, "perf_event_open")) {
                        err = -1;
                        goto destroy_skel;
                }

                skel->links.send_signal_perf =
                        bpf_program__attach_perf_event(skel->progs.send_signal_perf, pmu_fd);
                if (!ASSERT_OK_PTR(skel->links.send_signal_perf, "attach_perf_event"))
                        goto disable_pmu;
        }

        /* wait until child signal handler installed */
        ASSERT_EQ(read(pipe_c2p[0], buf, 1), 1, "pipe_read");

        /* trigger the bpf send_signal */
        skel->bss->signal_thread = signal_thread;
        skel->bss->sig = SIGUSR1;
        if (!remote) {
                skel->bss->target_pid = 0;
                skel->bss->pid = pid;
        } else {
                skel->bss->target_pid = pid;
                skel->bss->pid = getpid();
        }

        /* notify child that bpf program can send_signal now */
        ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");

        for (retry_count = 0;;) {
                /* For the remote test, the BPF program is triggered from this
                 * process but the other process/thread is signaled.
                 */
                if (remote) {
                        if (!attr) {
                                for (int i = 0; i < 10; i++)
                                        usleep(1);
                        } else {
                                for (int i = 0; i < 100000000; i++)
                                        j /= i + 1;
                        }
                }
                /* wait for result */
                err = read_with_timeout(pipe_c2p[0], buf, 1, 100);
                if (err == -EAGAIN && retry_count++ < 10000)
                        continue;
                break;
        }
        if (!ASSERT_GE(err, 0, "reading pipe"))
                goto disable_pmu;
        if (!ASSERT_GT(err, 0, "reading pipe error: size 0")) {
                err = -1;
                goto disable_pmu;
        }

        ASSERT_EQ(buf[0], 8, "incorrect result");

        /* notify child safe to exit */
        ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");

disable_pmu:
        close(pmu_fd);
destroy_skel:
        test_send_signal_kern__destroy(skel);
        /* restore the old priority */
        if (remote)
                ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority");
skel_open_load_failure:
        close(pipe_c2p[0]);
        close(pipe_p2c[1]);
        /*
         * Child is either about to exit cleanly or stuck in case of errors.
         * Nudge it to exit.
         */
        kill(pid, SIGKILL);
        wait(NULL);
}

static void test_send_signal_tracepoint(bool signal_thread, bool remote)
{
        test_send_signal_common(NULL, signal_thread, remote);
}

static void test_send_signal_perf(bool signal_thread, bool remote)
{
        struct perf_event_attr attr = {
                .freq = 1,
                .sample_freq = 1000,
                .type = PERF_TYPE_SOFTWARE,
                .config = PERF_COUNT_SW_CPU_CLOCK,
        };

        test_send_signal_common(&attr, signal_thread, remote);
}

static void test_send_signal_nmi(bool signal_thread, bool remote)
{
        struct perf_event_attr attr = {
                .freq = 1,
                .sample_freq = 1000,
                .type = PERF_TYPE_HARDWARE,
                .config = PERF_COUNT_HW_CPU_CYCLES,
        };
        int pmu_fd;

        /* Some setups (e.g. virtual machines) might run with hardware
         * perf events disabled. If this is the case, skip this test.
         */
        pmu_fd = syscall(__NR_perf_event_open, &attr, 0 /* pid */,
                         -1 /* cpu */, -1 /* group_fd */, 0 /* flags */);
        if (pmu_fd == -1) {
                if (errno == ENOENT || errno == EOPNOTSUPP) {
                        printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
                               __func__);
                        test__skip();
                        return;
                }
                /* Let the test fail with a more informative message */
        } else {
                close(pmu_fd);
        }

        test_send_signal_common(&attr, signal_thread, remote);
}

void test_send_signal(void)
{
        if (test__start_subtest("send_signal_tracepoint"))
                test_send_signal_tracepoint(false, false);
        if (test__start_subtest("send_signal_perf"))
                test_send_signal_perf(false, false);
        if (test__start_subtest("send_signal_nmi"))
                test_send_signal_nmi(false, false);
        if (test__start_subtest("send_signal_tracepoint_thread"))
                test_send_signal_tracepoint(true, false);
        if (test__start_subtest("send_signal_perf_thread"))
                test_send_signal_perf(true, false);
        if (test__start_subtest("send_signal_nmi_thread"))
                test_send_signal_nmi(true, false);

        /* Signal remote thread and thread group */
        if (test__start_subtest("send_signal_tracepoint_remote"))
                test_send_signal_tracepoint(false, true);
        if (test__start_subtest("send_signal_perf_remote"))
                test_send_signal_perf(false, true);
        if (test__start_subtest("send_signal_nmi_remote"))
                test_send_signal_nmi(false, true);
        if (test__start_subtest("send_signal_tracepoint_thread_remote"))
                test_send_signal_tracepoint(true, true);
        if (test__start_subtest("send_signal_perf_thread_remote"))
                test_send_signal_perf(true, true);
        if (test__start_subtest("send_signal_nmi_thread_remote"))
                test_send_signal_nmi(true, true);
}