// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook

#include <linux/bpf.h>
#include <stdint.h>
#include <stdbool.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>

char _license[] SEC("license") = "GPL";

struct {
        char in[256];
        char out[256];
        bool skip;
        uint64_t my_pid_tgid;
} data = {};

struct core_reloc_kernel_output {
        int valid[10];
        /* we have test_progs[-flavor], so cut flavor part */
        char comm[sizeof("test_progs")];
        int comm_len;
        bool local_task_struct_matches;
};

struct task_struct {
        int pid;
        int tgid;
        char comm[16];
        struct task_struct *group_leader;
};

struct mm_struct___wrong {
    int abc_whatever_should_not_exist;
};

struct task_struct___local {
    int pid;
    struct mm_struct___wrong *mm;
};

#define CORE_READ(dst, src) bpf_core_read(dst, sizeof(*(dst)), src)

SEC("raw_tracepoint/sys_enter")
int test_core_kernel(void *ctx)
{
        /* Support for the BPF_TYPE_MATCHES argument to the
         * __builtin_preserve_type_info builtin was added at some point during
         * development of clang 15 and it's what we require for this test.
         */
#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
        struct task_struct *task = (void *)bpf_get_current_task();
        struct core_reloc_kernel_output *out = (void *)&data.out;
        uint64_t pid_tgid = bpf_get_current_pid_tgid();
        int32_t real_tgid = (int32_t)pid_tgid;
        int pid, tgid;

        if (data.my_pid_tgid != pid_tgid)
                return 0;

        if (CORE_READ(&pid, &task->pid) ||
            CORE_READ(&tgid, &task->tgid))
                return 1;

        /* validate pid + tgid matches */
        out->valid[0] = (((uint64_t)pid << 32) | tgid) == pid_tgid;

        /* test variadic BPF_CORE_READ macros */
        out->valid[1] = BPF_CORE_READ(task,
                                      tgid) == real_tgid;
        out->valid[2] = BPF_CORE_READ(task,
                                      group_leader,
                                      tgid) == real_tgid;
        out->valid[3] = BPF_CORE_READ(task,
                                      group_leader, group_leader,
                                      tgid) == real_tgid;
        out->valid[4] = BPF_CORE_READ(task,
                                      group_leader, group_leader, group_leader,
                                      tgid) == real_tgid;
        out->valid[5] = BPF_CORE_READ(task,
                                      group_leader, group_leader, group_leader,
                                      group_leader,
                                      tgid) == real_tgid;
        out->valid[6] = BPF_CORE_READ(task,
                                      group_leader, group_leader, group_leader,
                                      group_leader, group_leader,
                                      tgid) == real_tgid;
        out->valid[7] = BPF_CORE_READ(task,
                                      group_leader, group_leader, group_leader,
                                      group_leader, group_leader, group_leader,
                                      tgid) == real_tgid;
        out->valid[8] = BPF_CORE_READ(task,
                                      group_leader, group_leader, group_leader,
                                      group_leader, group_leader, group_leader,
                                      group_leader,
                                      tgid) == real_tgid;
        out->valid[9] = BPF_CORE_READ(task,
                                      group_leader, group_leader, group_leader,
                                      group_leader, group_leader, group_leader,
                                      group_leader, group_leader,
                                      tgid) == real_tgid;

        /* test BPF_CORE_READ_STR_INTO() returns correct code and contents */
        out->comm_len = BPF_CORE_READ_STR_INTO(
                &out->comm, task,
                group_leader, group_leader, group_leader, group_leader,
                group_leader, group_leader, group_leader, group_leader,
                comm);

        out->local_task_struct_matches = bpf_core_type_matches(struct task_struct___local);
#else
        data.skip = true;
#endif
        return 0;
}