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// 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;
};
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);
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_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_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";
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