// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */

#define _GNU_SOURCE
#include <linux/compiler.h>
#include <linux/ring_buffer.h>
#include <linux/build_bug.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/sysinfo.h>
#include <test_progs.h>
#include <uapi/linux/bpf.h>
#include <unistd.h>

#include "user_ringbuf_fail.skel.h"
#include "user_ringbuf_success.skel.h"

#include "../progs/test_user_ringbuf.h"

static const long c_sample_size = sizeof(struct sample) + BPF_RINGBUF_HDR_SZ;
static long c_ringbuf_size, c_max_entries;

static void drain_current_samples(void)
{
        syscall(__NR_getpgid);
}

static int write_samples(struct user_ring_buffer *ringbuf, uint32_t num_samples)
{
        int i, err = 0;

        /* Write some number of samples to the ring buffer. */
        for (i = 0; i < num_samples; i++) {
                struct sample *entry;
                int read;

                entry = user_ring_buffer__reserve(ringbuf, sizeof(*entry));
                if (!entry) {
                        err = -errno;
                        goto done;
                }

                entry->pid = getpid();
                entry->seq = i;
                entry->value = i * i;

                read = snprintf(entry->comm, sizeof(entry->comm), "%u", i);
                if (read <= 0) {
                        /* Assert on the error path to avoid spamming logs with
                         * mostly success messages.
                         */
                        ASSERT_GT(read, 0, "snprintf_comm");
                        err = read;
                        user_ring_buffer__discard(ringbuf, entry);
                        goto done;
                }

                user_ring_buffer__submit(ringbuf, entry);
        }

done:
        drain_current_samples();

        return err;
}

static struct user_ringbuf_success *open_load_ringbuf_skel(void)
{
        struct user_ringbuf_success *skel;
        int err;

        skel = user_ringbuf_success__open();
        if (!ASSERT_OK_PTR(skel, "skel_open"))
                return NULL;

        err = bpf_map__set_max_entries(skel->maps.user_ringbuf, c_ringbuf_size);
        if (!ASSERT_OK(err, "set_max_entries"))
                goto cleanup;

        err = bpf_map__set_max_entries(skel->maps.kernel_ringbuf, c_ringbuf_size);
        if (!ASSERT_OK(err, "set_max_entries"))
                goto cleanup;

        err = user_ringbuf_success__load(skel);
        if (!ASSERT_OK(err, "skel_load"))
                goto cleanup;

        return skel;

cleanup:
        user_ringbuf_success__destroy(skel);
        return NULL;
}

static void test_user_ringbuf_mappings(void)
{
        int err, rb_fd;
        int page_size = getpagesize();
        void *mmap_ptr;
        struct user_ringbuf_success *skel;

        skel = open_load_ringbuf_skel();
        if (!skel)
                return;

        rb_fd = bpf_map__fd(skel->maps.user_ringbuf);
        /* cons_pos can be mapped R/O, can't add +X with mprotect. */
        mmap_ptr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, rb_fd, 0);
        ASSERT_OK_PTR(mmap_ptr, "ro_cons_pos");
        ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_WRITE), "write_cons_pos_protect");
        ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_EXEC), "exec_cons_pos_protect");
        ASSERT_ERR_PTR(mremap(mmap_ptr, 0, 4 * page_size, MREMAP_MAYMOVE), "wr_prod_pos");
        err = -errno;
        ASSERT_ERR(err, "wr_prod_pos_err");
        ASSERT_OK(munmap(mmap_ptr, page_size), "unmap_ro_cons");

        /* prod_pos can be mapped RW, can't add +X with mprotect. */
        mmap_ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED,
                        rb_fd, page_size);
        ASSERT_OK_PTR(mmap_ptr, "rw_prod_pos");
        ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_EXEC), "exec_prod_pos_protect");
        err = -errno;
        ASSERT_ERR(err, "wr_prod_pos_err");
        ASSERT_OK(munmap(mmap_ptr, page_size), "unmap_rw_prod");

        /* data pages can be mapped RW, can't add +X with mprotect. */
        mmap_ptr = mmap(NULL, page_size, PROT_WRITE, MAP_SHARED, rb_fd,
                        2 * page_size);
        ASSERT_OK_PTR(mmap_ptr, "rw_data");
        ASSERT_ERR(mprotect(mmap_ptr, page_size, PROT_EXEC), "exec_data_protect");
        err = -errno;
        ASSERT_ERR(err, "exec_data_err");
        ASSERT_OK(munmap(mmap_ptr, page_size), "unmap_rw_data");

        user_ringbuf_success__destroy(skel);
}

static int load_skel_create_ringbufs(struct user_ringbuf_success **skel_out,
                                     struct ring_buffer **kern_ringbuf_out,
                                     ring_buffer_sample_fn callback,
                                     struct user_ring_buffer **user_ringbuf_out)
{
        struct user_ringbuf_success *skel;
        struct ring_buffer *kern_ringbuf = NULL;
        struct user_ring_buffer *user_ringbuf = NULL;
        int err = -ENOMEM, rb_fd;

        skel = open_load_ringbuf_skel();
        if (!skel)
                return err;

        /* only trigger BPF program for current process */
        skel->bss->pid = getpid();

        if (kern_ringbuf_out) {
                rb_fd = bpf_map__fd(skel->maps.kernel_ringbuf);
                kern_ringbuf = ring_buffer__new(rb_fd, callback, skel, NULL);
                if (!ASSERT_OK_PTR(kern_ringbuf, "kern_ringbuf_create"))
                        goto cleanup;

                *kern_ringbuf_out = kern_ringbuf;
        }

        if (user_ringbuf_out) {
                rb_fd = bpf_map__fd(skel->maps.user_ringbuf);
                user_ringbuf = user_ring_buffer__new(rb_fd, NULL);
                if (!ASSERT_OK_PTR(user_ringbuf, "user_ringbuf_create"))
                        goto cleanup;

                *user_ringbuf_out = user_ringbuf;
                ASSERT_EQ(skel->bss->read, 0, "no_reads_after_load");
        }

        err = user_ringbuf_success__attach(skel);
        if (!ASSERT_OK(err, "skel_attach"))
                goto cleanup;

        *skel_out = skel;
        return 0;

cleanup:
        if (kern_ringbuf_out)
                *kern_ringbuf_out = NULL;
        if (user_ringbuf_out)
                *user_ringbuf_out = NULL;
        ring_buffer__free(kern_ringbuf);
        user_ring_buffer__free(user_ringbuf);
        user_ringbuf_success__destroy(skel);
        return err;
}

static int load_skel_create_user_ringbuf(struct user_ringbuf_success **skel_out,
                                         struct user_ring_buffer **ringbuf_out)
{
        return load_skel_create_ringbufs(skel_out, NULL, NULL, ringbuf_out);
}

static void manually_write_test_invalid_sample(struct user_ringbuf_success *skel,
                                               __u32 size, __u64 producer_pos, int err)
{
        void *data_ptr;
        __u64 *producer_pos_ptr;
        int rb_fd, page_size = getpagesize();

        rb_fd = bpf_map__fd(skel->maps.user_ringbuf);

        ASSERT_EQ(skel->bss->read, 0, "num_samples_before_bad_sample");

        /* Map the producer_pos as RW. */
        producer_pos_ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
                                MAP_SHARED, rb_fd, page_size);
        ASSERT_OK_PTR(producer_pos_ptr, "producer_pos_ptr");

        /* Map the data pages as RW. */
        data_ptr = mmap(NULL, page_size, PROT_WRITE, MAP_SHARED, rb_fd, 2 * page_size);
        ASSERT_OK_PTR(data_ptr, "rw_data");

        memset(data_ptr, 0, BPF_RINGBUF_HDR_SZ);
        *(__u32 *)data_ptr = size;

        /* Synchronizes with smp_load_acquire() in __bpf_user_ringbuf_peek() in the kernel. */
        smp_store_release(producer_pos_ptr, producer_pos + BPF_RINGBUF_HDR_SZ);

        drain_current_samples();
        ASSERT_EQ(skel->bss->read, 0, "num_samples_after_bad_sample");
        ASSERT_EQ(skel->bss->err, err, "err_after_bad_sample");

        ASSERT_OK(munmap(producer_pos_ptr, page_size), "unmap_producer_pos");
        ASSERT_OK(munmap(data_ptr, page_size), "unmap_data_ptr");
}

static void test_user_ringbuf_post_misaligned(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err;
        __u32 size = (1 << 5) + 7;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (!ASSERT_OK(err, "misaligned_skel"))
                return;

        manually_write_test_invalid_sample(skel, size, size, -EINVAL);
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_post_producer_wrong_offset(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err;
        __u32 size = (1 << 5);

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (!ASSERT_OK(err, "wrong_offset_skel"))
                return;

        manually_write_test_invalid_sample(skel, size, size - 8, -EINVAL);
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_post_larger_than_ringbuf_sz(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err;
        __u32 size = c_ringbuf_size;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (!ASSERT_OK(err, "huge_sample_skel"))
                return;

        manually_write_test_invalid_sample(skel, size, size, -E2BIG);
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_basic(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (!ASSERT_OK(err, "ringbuf_basic_skel"))
                return;

        ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");

        err = write_samples(ringbuf, 2);
        if (!ASSERT_OK(err, "write_samples"))
                goto cleanup;

        ASSERT_EQ(skel->bss->read, 2, "num_samples_read_after");

cleanup:
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_sample_full_ring_buffer(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err;
        void *sample;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (!ASSERT_OK(err, "ringbuf_full_sample_skel"))
                return;

        sample = user_ring_buffer__reserve(ringbuf, c_ringbuf_size - BPF_RINGBUF_HDR_SZ);
        if (!ASSERT_OK_PTR(sample, "full_sample"))
                goto cleanup;

        user_ring_buffer__submit(ringbuf, sample);
        ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");
        drain_current_samples();
        ASSERT_EQ(skel->bss->read, 1, "num_samples_read_after");

cleanup:
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_post_alignment_autoadjust(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        struct sample *sample;
        int err;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (!ASSERT_OK(err, "ringbuf_align_autoadjust_skel"))
                return;

        /* libbpf should automatically round any sample up to an 8-byte alignment. */
        sample = user_ring_buffer__reserve(ringbuf, sizeof(*sample) + 1);
        ASSERT_OK_PTR(sample, "reserve_autoaligned");
        user_ring_buffer__submit(ringbuf, sample);

        ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");
        drain_current_samples();
        ASSERT_EQ(skel->bss->read, 1, "num_samples_read_after");

        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_overfill(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (err)
                return;

        err = write_samples(ringbuf, c_max_entries * 5);
        ASSERT_ERR(err, "write_samples");
        ASSERT_EQ(skel->bss->read, c_max_entries, "max_entries");

        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_discards_properly_ignored(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err, num_discarded = 0;
        __u64 *token;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (err)
                return;

        ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");

        while (1) {
                /* Write samples until the buffer is full. */
                token = user_ring_buffer__reserve(ringbuf, sizeof(*token));
                if (!token)
                        break;

                user_ring_buffer__discard(ringbuf, token);
                num_discarded++;
        }

        if (!ASSERT_GE(num_discarded, 0, "num_discarded"))
                goto cleanup;

        /* Should not read any samples, as they are all discarded. */
        ASSERT_EQ(skel->bss->read, 0, "num_pre_kick");
        drain_current_samples();
        ASSERT_EQ(skel->bss->read, 0, "num_post_kick");

        /* Now that the ring buffer has been drained, we should be able to
         * reserve another token.
         */
        token = user_ring_buffer__reserve(ringbuf, sizeof(*token));

        if (!ASSERT_OK_PTR(token, "new_token"))
                goto cleanup;

        user_ring_buffer__discard(ringbuf, token);
cleanup:
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void test_user_ringbuf_loop(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        uint32_t total_samples = 8192;
        uint32_t remaining_samples = total_samples;
        int err;

        if (!ASSERT_LT(c_max_entries, total_samples, "compare_c_max_entries"))
                return;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (err)
                return;

        do  {
                uint32_t curr_samples;

                curr_samples = remaining_samples > c_max_entries
                        ? c_max_entries : remaining_samples;
                err = write_samples(ringbuf, curr_samples);
                if (err != 0) {
                        /* Assert inside of if statement to avoid flooding logs
                         * on the success path.
                         */
                        ASSERT_OK(err, "write_samples");
                        goto cleanup;
                }

                remaining_samples -= curr_samples;
                ASSERT_EQ(skel->bss->read, total_samples - remaining_samples,
                          "current_batched_entries");
        } while (remaining_samples > 0);
        ASSERT_EQ(skel->bss->read, total_samples, "total_batched_entries");

cleanup:
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

static int send_test_message(struct user_ring_buffer *ringbuf,
                             enum test_msg_op op, s64 operand_64,
                             s32 operand_32)
{
        struct test_msg *msg;

        msg = user_ring_buffer__reserve(ringbuf, sizeof(*msg));
        if (!msg) {
                /* Assert on the error path to avoid spamming logs with mostly
                 * success messages.
                 */
                ASSERT_OK_PTR(msg, "reserve_msg");
                return -ENOMEM;
        }

        msg->msg_op = op;

        switch (op) {
        case TEST_MSG_OP_INC64:
        case TEST_MSG_OP_MUL64:
                msg->operand_64 = operand_64;
                break;
        case TEST_MSG_OP_INC32:
        case TEST_MSG_OP_MUL32:
                msg->operand_32 = operand_32;
                break;
        default:
                PRINT_FAIL("Invalid operand %d\n", op);
                user_ring_buffer__discard(ringbuf, msg);
                return -EINVAL;
        }

        user_ring_buffer__submit(ringbuf, msg);

        return 0;
}

static void kick_kernel_read_messages(void)
{
        syscall(__NR_prctl);
}

static int handle_kernel_msg(void *ctx, void *data, size_t len)
{
        struct user_ringbuf_success *skel = ctx;
        struct test_msg *msg = data;

        switch (msg->msg_op) {
        case TEST_MSG_OP_INC64:
                skel->bss->user_mutated += msg->operand_64;
                return 0;
        case TEST_MSG_OP_INC32:
                skel->bss->user_mutated += msg->operand_32;
                return 0;
        case TEST_MSG_OP_MUL64:
                skel->bss->user_mutated *= msg->operand_64;
                return 0;
        case TEST_MSG_OP_MUL32:
                skel->bss->user_mutated *= msg->operand_32;
                return 0;
        default:
                fprintf(stderr, "Invalid operand %d\n", msg->msg_op);
                return -EINVAL;
        }
}

static void drain_kernel_messages_buffer(struct ring_buffer *kern_ringbuf,
                                         struct user_ringbuf_success *skel)
{
        int cnt;

        cnt = ring_buffer__consume(kern_ringbuf);
        ASSERT_EQ(cnt, 8, "consume_kern_ringbuf");
        ASSERT_OK(skel->bss->err, "consume_kern_ringbuf_err");
}

static void test_user_ringbuf_msg_protocol(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *user_ringbuf;
        struct ring_buffer *kern_ringbuf;
        int err, i;
        __u64 expected_kern = 0;

        err = load_skel_create_ringbufs(&skel, &kern_ringbuf, handle_kernel_msg, &user_ringbuf);
        if (!ASSERT_OK(err, "create_ringbufs"))
                return;

        for (i = 0; i < 64; i++) {
                enum test_msg_op op = i % TEST_MSG_OP_NUM_OPS;
                __u64 operand_64 = TEST_OP_64;
                __u32 operand_32 = TEST_OP_32;

                err = send_test_message(user_ringbuf, op, operand_64, operand_32);
                if (err) {
                        /* Only assert on a failure to avoid spamming success logs. */
                        ASSERT_OK(err, "send_test_message");
                        goto cleanup;
                }

                switch (op) {
                case TEST_MSG_OP_INC64:
                        expected_kern += operand_64;
                        break;
                case TEST_MSG_OP_INC32:
                        expected_kern += operand_32;
                        break;
                case TEST_MSG_OP_MUL64:
                        expected_kern *= operand_64;
                        break;
                case TEST_MSG_OP_MUL32:
                        expected_kern *= operand_32;
                        break;
                default:
                        PRINT_FAIL("Unexpected op %d\n", op);
                        goto cleanup;
                }

                if (i % 8 == 0) {
                        kick_kernel_read_messages();
                        ASSERT_EQ(skel->bss->kern_mutated, expected_kern, "expected_kern");
                        ASSERT_EQ(skel->bss->err, 0, "bpf_prog_err");
                        drain_kernel_messages_buffer(kern_ringbuf, skel);
                }
        }

cleanup:
        ring_buffer__free(kern_ringbuf);
        user_ring_buffer__free(user_ringbuf);
        user_ringbuf_success__destroy(skel);
}

static void *kick_kernel_cb(void *arg)
{
        /* Kick the kernel, causing it to drain the ring buffer and then wake
         * up the test thread waiting on epoll.
         */
        syscall(__NR_prlimit64);

        return NULL;
}

static int spawn_kick_thread_for_poll(void)
{
        pthread_t thread;

        return pthread_create(&thread, NULL, kick_kernel_cb, NULL);
}

static void test_user_ringbuf_blocking_reserve(void)
{
        struct user_ringbuf_success *skel;
        struct user_ring_buffer *ringbuf;
        int err, num_written = 0;
        __u64 *token;

        err = load_skel_create_user_ringbuf(&skel, &ringbuf);
        if (err)
                return;

        ASSERT_EQ(skel->bss->read, 0, "num_samples_read_before");

        while (1) {
                /* Write samples until the buffer is full. */
                token = user_ring_buffer__reserve(ringbuf, sizeof(*token));
                if (!token)
                        break;

                *token = 0xdeadbeef;

                user_ring_buffer__submit(ringbuf, token);
                num_written++;
        }

        if (!ASSERT_GE(num_written, 0, "num_written"))
                goto cleanup;

        /* Should not have read any samples until the kernel is kicked. */
        ASSERT_EQ(skel->bss->read, 0, "num_pre_kick");

        /* We correctly time out after 1 second, without a sample. */
        token = user_ring_buffer__reserve_blocking(ringbuf, sizeof(*token), 1000);
        if (!ASSERT_EQ(token, NULL, "pre_kick_timeout_token"))
                goto cleanup;

        err = spawn_kick_thread_for_poll();
        if (!ASSERT_EQ(err, 0, "deferred_kick_thread\n"))
                goto cleanup;

        /* After spawning another thread that asynchronously kicks the kernel to
         * drain the messages, we're able to block and successfully get a
         * sample once we receive an event notification.
         */
        token = user_ring_buffer__reserve_blocking(ringbuf, sizeof(*token), 10000);

        if (!ASSERT_OK_PTR(token, "block_token"))
                goto cleanup;

        ASSERT_GT(skel->bss->read, 0, "num_post_kill");
        ASSERT_LE(skel->bss->read, num_written, "num_post_kill");
        ASSERT_EQ(skel->bss->err, 0, "err_post_poll");
        user_ring_buffer__discard(ringbuf, token);

cleanup:
        user_ring_buffer__free(ringbuf);
        user_ringbuf_success__destroy(skel);
}

#define SUCCESS_TEST(_func) { _func, #_func }

static struct {
        void (*test_callback)(void);
        const char *test_name;
} success_tests[] = {
        SUCCESS_TEST(test_user_ringbuf_mappings),
        SUCCESS_TEST(test_user_ringbuf_post_misaligned),
        SUCCESS_TEST(test_user_ringbuf_post_producer_wrong_offset),
        SUCCESS_TEST(test_user_ringbuf_post_larger_than_ringbuf_sz),
        SUCCESS_TEST(test_user_ringbuf_basic),
        SUCCESS_TEST(test_user_ringbuf_sample_full_ring_buffer),
        SUCCESS_TEST(test_user_ringbuf_post_alignment_autoadjust),
        SUCCESS_TEST(test_user_ringbuf_overfill),
        SUCCESS_TEST(test_user_ringbuf_discards_properly_ignored),
        SUCCESS_TEST(test_user_ringbuf_loop),
        SUCCESS_TEST(test_user_ringbuf_msg_protocol),
        SUCCESS_TEST(test_user_ringbuf_blocking_reserve),
};

void test_user_ringbuf(void)
{
        int i;

        c_ringbuf_size = getpagesize(); /* 1 page */
        c_max_entries = c_ringbuf_size / c_sample_size;

        for (i = 0; i < ARRAY_SIZE(success_tests); i++) {
                if (!test__start_subtest(success_tests[i].test_name))
                        continue;

                success_tests[i].test_callback();
        }

        RUN_TESTS(user_ringbuf_fail);
}