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

#include <stddef.h>
#include <linux/ptrace.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>

int valid = 0;
int run_cnt = 0;
int required_size_out = 0;
int written_stack_out = 0;
int written_global_out = 0;

struct {
        __u64 _a;
        __u64 _b;
        __u64 _c;
} fpbe[30] = {0};

SEC("perf_event")
int perf_branches(void *ctx)
{
        __u64 entries[4 * 3] = {0};
        int required_size, written_stack, written_global;

        ++run_cnt;

        /* write to stack */
        written_stack = bpf_read_branch_records(ctx, entries, sizeof(entries), 0);
        /* ignore spurious events */
        if (!written_stack)
                return 1;

        /* get required size */
        required_size = bpf_read_branch_records(ctx, NULL, 0,
                                                BPF_F_GET_BRANCH_RECORDS_SIZE);

        written_global = bpf_read_branch_records(ctx, fpbe, sizeof(fpbe), 0);
        /* ignore spurious events */
        if (!written_global)
                return 1;

        required_size_out = required_size;
        written_stack_out = written_stack;
        written_global_out = written_global;
        valid = 1;

        return 0;
}

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