rbtree.c | Explore in Territory

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

#include <vmlinux.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>
#include "bpf_experimental.h"

struct node_data {
	long key;
	long data;
	struct bpf_rb_node node;
};

struct root_nested_inner {
	struct bpf_spin_lock glock;
	struct bpf_rb_root root __contains(node_data, node);
};

struct root_nested {
	struct root_nested_inner inner;
};

long less_callback_ran = -1;
long removed_key = -1;
long first_data[2] = {-1, -1};

#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
private(A) struct bpf_spin_lock glock;
private(A) struct bpf_rb_root groot __contains(node_data, node);
private(A) struct bpf_rb_root groot_array[2] __contains(node_data, node);
private(A) struct bpf_rb_root groot_array_one[1] __contains(node_data, node);
private(B) struct root_nested groot_nested;

static bool less(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
	struct node_data *node_a;
	struct node_data *node_b;

	node_a = container_of(a, struct node_data, node);
	node_b = container_of(b, struct node_data, node);
	less_callback_ran = 1;

	return node_a->key < node_b->key;
}

static long __add_three(struct bpf_rb_root *root, struct bpf_spin_lock *lock)
{
	struct node_data *n, *m;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;
	n->key = 5;

	m = bpf_obj_new(typeof(*m));
	if (!m) {
		bpf_obj_drop(n);
		return 2;
	}
	m->key = 1;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_rbtree_add(&groot, &m->node, less);
	bpf_spin_unlock(&glock);

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 3;
	n->key = 3;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_spin_unlock(&glock);
	return 0;
}

SEC("tc")
long rbtree_add_nodes(void *ctx)
{
	return __add_three(&groot, &glock);
}

SEC("tc")
long rbtree_add_nodes_nested(void *ctx)
{
	return __add_three(&groot_nested.inner.root, &groot_nested.inner.glock);
}

SEC("tc")
long rbtree_add_and_remove(void *ctx)
{
	struct bpf_rb_node *res = NULL;
	struct node_data *n, *m = NULL;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		goto err_out;
	n->key = 5;

	m = bpf_obj_new(typeof(*m));
	if (!m)
		goto err_out;
	m->key = 3;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_rbtree_add(&groot, &m->node, less);
	res = bpf_rbtree_remove(&groot, &n->node);
	bpf_spin_unlock(&glock);

	if (!res)
		return 1;

	n = container_of(res, struct node_data, node);
	removed_key = n->key;
	bpf_obj_drop(n);

	return 0;
err_out:
	if (n)
		bpf_obj_drop(n);
	if (m)
		bpf_obj_drop(m);
	return 1;
}

SEC("tc")
long rbtree_add_and_remove_array(void *ctx)
{
	struct bpf_rb_node *res1 = NULL, *res2 = NULL, *res3 = NULL;
	struct node_data *nodes[3][2] = {{NULL, NULL}, {NULL, NULL}, {NULL, NULL}};
	struct node_data *n;
	long k1 = -1, k2 = -1, k3 = -1;
	int i, j;

	for (i = 0; i < 3; i++) {
		for (j = 0; j < 2; j++) {
			nodes[i][j] = bpf_obj_new(typeof(*nodes[i][j]));
			if (!nodes[i][j])
				goto err_out;
			nodes[i][j]->key = i * 2 + j;
		}
	}

	bpf_spin_lock(&glock);
	for (i = 0; i < 2; i++)
		for (j = 0; j < 2; j++)
			bpf_rbtree_add(&groot_array[i], &nodes[i][j]->node, less);
	for (j = 0; j < 2; j++)
		bpf_rbtree_add(&groot_array_one[0], &nodes[2][j]->node, less);
	res1 = bpf_rbtree_remove(&groot_array[0], &nodes[0][0]->node);
	res2 = bpf_rbtree_remove(&groot_array[1], &nodes[1][0]->node);
	res3 = bpf_rbtree_remove(&groot_array_one[0], &nodes[2][0]->node);
	bpf_spin_unlock(&glock);

	if (res1) {
		n = container_of(res1, struct node_data, node);
		k1 = n->key;
		bpf_obj_drop(n);
	}
	if (res2) {
		n = container_of(res2, struct node_data, node);
		k2 = n->key;
		bpf_obj_drop(n);
	}
	if (res3) {
		n = container_of(res3, struct node_data, node);
		k3 = n->key;
		bpf_obj_drop(n);
	}
	if (k1 != 0 || k2 != 2 || k3 != 4)
		return 2;

	return 0;

err_out:
	for (i = 0; i < 3; i++) {
		for (j = 0; j < 2; j++) {
			if (nodes[i][j])
				bpf_obj_drop(nodes[i][j]);
		}
	}
	return 1;
}

SEC("tc")
long rbtree_first_and_remove(void *ctx)
{
	struct bpf_rb_node *res = NULL;
	struct node_data *n, *m, *o;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;
	n->key = 3;
	n->data = 4;

	m = bpf_obj_new(typeof(*m));
	if (!m)
		goto err_out;
	m->key = 5;
	m->data = 6;

	o = bpf_obj_new(typeof(*o));
	if (!o)
		goto err_out;
	o->key = 1;
	o->data = 2;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_rbtree_add(&groot, &m->node, less);
	bpf_rbtree_add(&groot, &o->node, less);

	res = bpf_rbtree_first(&groot);
	if (!res) {
		bpf_spin_unlock(&glock);
		return 2;
	}

	o = container_of(res, struct node_data, node);
	first_data[0] = o->data;

	res = bpf_rbtree_remove(&groot, &o->node);
	bpf_spin_unlock(&glock);

	if (!res)
		return 5;

	o = container_of(res, struct node_data, node);
	removed_key = o->key;
	bpf_obj_drop(o);

	bpf_spin_lock(&glock);
	res = bpf_rbtree_first(&groot);
	if (!res) {
		bpf_spin_unlock(&glock);
		return 3;
	}

	o = container_of(res, struct node_data, node);
	first_data[1] = o->data;
	bpf_spin_unlock(&glock);

	return 0;
err_out:
	if (n)
		bpf_obj_drop(n);
	if (m)
		bpf_obj_drop(m);
	return 1;
}

SEC("tc")
long rbtree_api_release_aliasing(void *ctx)
{
	struct node_data *n, *m, *o;
	struct bpf_rb_node *res, *res2;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;
	n->key = 41;
	n->data = 42;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_spin_unlock(&glock);

	bpf_spin_lock(&glock);

	/* m and o point to the same node,
	 * but verifier doesn't know this
	 */
	res = bpf_rbtree_first(&groot);
	if (!res)
		goto err_out;
	o = container_of(res, struct node_data, node);

	res = bpf_rbtree_first(&groot);
	if (!res)
		goto err_out;
	m = container_of(res, struct node_data, node);

	res = bpf_rbtree_remove(&groot, &m->node);
	/* Retval of previous remove returns an owning reference to m,
	 * which is the same node non-owning ref o is pointing at.
	 * We can safely try to remove o as the second rbtree_remove will
	 * return NULL since the node isn't in a tree.
	 *
	 * Previously we relied on the verifier type system + rbtree_remove
	 * invalidating non-owning refs to ensure that rbtree_remove couldn't
	 * fail, but now rbtree_remove does runtime checking so we no longer
	 * invalidate non-owning refs after remove.
	 */
	res2 = bpf_rbtree_remove(&groot, &o->node);

	bpf_spin_unlock(&glock);

	if (res) {
		o = container_of(res, struct node_data, node);
		first_data[0] = o->data;
		bpf_obj_drop(o);
	}
	if (res2) {
		/* The second remove fails, so res2 is null and this doesn't
		 * execute
		 */
		m = container_of(res2, struct node_data, node);
		first_data[1] = m->data;
		bpf_obj_drop(m);
	}
	return 0;

err_out:
	bpf_spin_unlock(&glock);
	return 1;
}

char _license[] SEC("license") = "GPL";
linux/tools/testing/selftests/bpf/progs/rbtree.c
