Commit 312aa5bd authored by Dave Marchevsky's avatar Dave Marchevsky Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add tests for rbtree API interaction in sleepable progs 



Confirm that the following sleepable prog states fail verification:
  * bpf_rcu_read_unlock before bpf_spin_unlock
     * RCU CS will last at least as long as spin_lock CS

Also confirm that correct usage passes verification, specifically:
  * Explicit use of bpf_rcu_read_{lock, unlock} in sleepable test prog
  * Implied RCU CS due to spin_lock CS

None of the selftest progs actually attach to bpf_testmod's
bpf_testmod_test_read.

Signed-off-by: default avatarDave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230821193311.3290257-8-davemarchevsky@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 5861d1e8

tools/testing/selftests/bpf/progs/refcounted_kptr.c

+71 −0
Original line number Diff line number Diff line
@@ -8,6 +8,9 @@ 
#include "bpf_misc.h"

#include "bpf_experimental.h"



extern void bpf_rcu_read_lock(void) __ksym;

extern void bpf_rcu_read_unlock(void) __ksym;



struct node_data {

	long key;

	long list_data;
@@ -497,4 +500,72 @@ long rbtree_wrong_owner_remove_fail_a2(void *ctx) 
	return 0;

}



SEC("?fentry.s/bpf_testmod_test_read")

__success

int BPF_PROG(rbtree_sleepable_rcu,

	     struct file *file, struct kobject *kobj,

	     struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len)

{

	struct bpf_rb_node *rb;

	struct node_data *n, *m = NULL;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return 0;



	bpf_rcu_read_lock();

	bpf_spin_lock(&lock);

	bpf_rbtree_add(&root, &n->r, less);

	rb = bpf_rbtree_first(&root);

	if (!rb)

		goto err_out;



	rb = bpf_rbtree_remove(&root, rb);

	if (!rb)

		goto err_out;



	m = container_of(rb, struct node_data, r);



err_out:

	bpf_spin_unlock(&lock);

	bpf_rcu_read_unlock();

	if (m)

		bpf_obj_drop(m);

	return 0;

}



SEC("?fentry.s/bpf_testmod_test_read")

__success

int BPF_PROG(rbtree_sleepable_rcu_no_explicit_rcu_lock,

	     struct file *file, struct kobject *kobj,

	     struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len)

{

	struct bpf_rb_node *rb;

	struct node_data *n, *m = NULL;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return 0;



	/* No explicit bpf_rcu_read_lock */

	bpf_spin_lock(&lock);

	bpf_rbtree_add(&root, &n->r, less);

	rb = bpf_rbtree_first(&root);

	if (!rb)

		goto err_out;



	rb = bpf_rbtree_remove(&root, rb);

	if (!rb)

		goto err_out;



	m = container_of(rb, struct node_data, r);



err_out:

	bpf_spin_unlock(&lock);

	/* No explicit bpf_rcu_read_unlock */

	if (m)

		bpf_obj_drop(m);

	return 0;

}



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

tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c

+28 −0
Original line number Diff line number Diff line
@@ -13,6 +13,9 @@ struct node_acquire { 
	struct bpf_refcount refcount;

};



extern void bpf_rcu_read_lock(void) __ksym;

extern void bpf_rcu_read_unlock(void) __ksym;



#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_acquire, node);
@@ -71,4 +74,29 @@ long rbtree_refcounted_node_ref_escapes_owning_input(void *ctx) 
	return 0;

}



SEC("?fentry.s/bpf_testmod_test_read")

__failure __msg("function calls are not allowed while holding a lock")

int BPF_PROG(rbtree_fail_sleepable_lock_across_rcu,

	     struct file *file, struct kobject *kobj,

	     struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len)

{

	struct node_acquire *n;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return 0;



	/* spin_{lock,unlock} are in different RCU CS */

	bpf_rcu_read_lock();

	bpf_spin_lock(&glock);

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

	bpf_rcu_read_unlock();



	bpf_rcu_read_lock();

	bpf_spin_unlock(&glock);

	bpf_rcu_read_unlock();



	return 0;

}



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