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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <errno.h>
extern int bpf_kfunc_implicit_arg(int a) __weak __ksym;
char _license[] SEC("license") = "GPL";
/* Shared arg checks; reports arg count and aux, returns 1 on success. */
static __always_inline __u64
check_implicit_args(void *ctx, __u64 *arg_cnt, __u64 *aux_arg)
{
__u64 a = 0, aux = 0, z = 0;
__u64 result;
__s64 err;
*arg_cnt = bpf_get_func_arg_cnt(ctx);
result = *arg_cnt == 2;
err = bpf_get_func_arg(ctx, 0, &a);
result &= err == 0 && (int)a == 5;
err = bpf_get_func_arg(ctx, 1, &aux);
*aux_arg = aux;
result &= err == 0 && aux != 0;
err = bpf_get_func_arg(ctx, 2, &z);
result &= err == -EINVAL;
return result;
}
__u64 fentry_result;
__u64 fentry_arg_cnt;
__u64 fentry_aux_arg;
SEC("fentry/bpf_kfunc_implicit_arg")
int BPF_PROG(trace_implicit_arg_fentry)
{
__u64 ret = 0;
__s64 err;
fentry_result = check_implicit_args(ctx, &fentry_arg_cnt, &fentry_aux_arg);
err = bpf_get_func_ret(ctx, &ret);
fentry_result &= err == -EOPNOTSUPP;
return 0;
}
__u64 fexit_result;
__u64 fexit_arg_cnt;
__u64 fexit_aux_arg;
SEC("fexit/bpf_kfunc_implicit_arg")
int BPF_PROG(trace_implicit_arg_fexit)
{
__u64 ret = 0;
__s64 err;
fexit_result = check_implicit_args(ctx, &fexit_arg_cnt, &fexit_aux_arg);
err = bpf_get_func_ret(ctx, &ret);
fexit_result &= err == 0 && ret == 5;
return 0;
}
SEC("syscall")
int trigger_implicit_arg(void *ctx)
{
return bpf_kfunc_implicit_arg(5);
}
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