// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */

#define BPF_NO_KFUNC_PROTOTYPES
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "bpf_experimental.h"
#include <bpf_arena_common.h>

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

/*
 * The module types as a vmlinux.h generated by a libbpf that does not render
 * the arena tag with its address space shows them: an attribute on a pointer
 * in the kernel address space, so the program has to cast the member to the
 * arena address space before using it.
 */
#define __arena_tag	__attribute__((btf_type_tag("arena")))
#define __nullable_tag	__attribute__((btf_type_tag("nullable")))

struct bpf_testmod_arena_member_args {
	__u64 __arena_tag *ptr;
	__u64 __arena_tag __nullable_tag *null_ptr;
	struct {
		__u64 __arena_tag *ptr;
	} nested;
} __attribute__((preserve_access_index));

struct bpf_testmod_ops3 {
	int (*test_arena_member)(struct bpf_testmod_arena_member_args *args);
};

int bpf_testmod_ops3_call_test_arena_member(__u64 *ptr__arena) __ksym;

struct {
	__uint(type, BPF_MAP_TYPE_ARENA);
	__uint(map_flags, BPF_F_MMAPABLE);
	__uint(max_entries, 2);
} arena SEC(".maps");

/* also associates the callback with the arena */
u64 __arena arena_touch;

SEC("struct_ops/test_arena_member")
int BPF_PROG(test_arena_member_render_cb, struct bpf_testmod_arena_member_args *args)
{
	u64 __arena *ptr = (u64 __arena *)args->ptr;

	arena_touch++;
	*ptr += 1;
	if (args->null_ptr)
		return 0xbad;
	*(u64 __arena *)args->nested.ptr += 1;
	return 0;
}

SEC(".struct_ops.link")
struct bpf_testmod_ops3 testmod_arena_member_render = {
	.test_arena_member = (void *)test_arena_member_render_cb,
};

SEC("syscall")
int trigger(void *ctx)
{
#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
	u64 __arena *val;
	int ret;

	val = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
	if (!val)
		return 1;

	*val = 41;
	ret = bpf_testmod_ops3_call_test_arena_member((u64 *)val);
	if (ret)
		return 2;
	/* ptr and nested.ptr each added one */
	if (*val != 43)
		return 3;

	bpf_arena_free_pages(&arena, (void __arena *)val, 1);
#endif
	return 0;
}