Commit a5a197df authored by David Vernet's avatar David Vernet Committed by Alexei Starovoitov
Browse files

bpf/selftests: Test using global cpumask kptr with RCU 



Now that struct bpf_cpumask * is considered an RCU-safe type according
to the verifier, we should add tests that validate its common usages.
This patch adds those tests to the cpumask test suite. A subsequent
changes will remove bpf_cpumask_kptr_get(), and will adjust the selftest
and BPF documentation accordingly.

Signed-off-by: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230316054028.88924-4-void@manifault.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 63d2d83d

tools/testing/selftests/bpf/prog_tests/cpumask.c

+1 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ static const char * const cpumask_success_testcases[] = { 
	"test_insert_leave",

	"test_insert_remove_release",

	"test_insert_kptr_get_release",

	"test_global_mask_rcu",

};



static void verify_success(const char *prog_name)

tools/testing/selftests/bpf/progs/cpumask_common.h

+6 −0
Original line number Diff line number Diff line
@@ -9,6 +9,9 @@ 


int err;



#define private(name) SEC(".bss." #name) __hidden __attribute__((aligned(8)))

private(MASK) static struct bpf_cpumask __kptr * global_mask;



struct __cpumask_map_value {

	struct bpf_cpumask __kptr * cpumask;

};
@@ -51,6 +54,9 @@ void bpf_cpumask_copy(struct bpf_cpumask *dst, const struct cpumask *src) __ksym 
u32 bpf_cpumask_any(const struct cpumask *src) __ksym;

u32 bpf_cpumask_any_and(const struct cpumask *src1, const struct cpumask *src2) __ksym;



void bpf_rcu_read_lock(void) __ksym;

void bpf_rcu_read_unlock(void) __ksym;



static inline const struct cpumask *cast(struct bpf_cpumask *cpumask)

{

	return (const struct cpumask *)cpumask;

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

+62 −0
Original line number Diff line number Diff line
@@ -127,3 +127,65 @@ int BPF_PROG(test_cpumask_null, struct task_struct *task, u64 clone_flags) 


	return 0;

}



SEC("tp_btf/task_newtask")

__failure __msg("R2 must be a rcu pointer")

int BPF_PROG(test_global_mask_out_of_rcu, struct task_struct *task, u64 clone_flags)

{

	struct bpf_cpumask *local, *prev;



	local = create_cpumask();

	if (!local)

		return 0;



	prev = bpf_kptr_xchg(&global_mask, local);

	if (prev) {

		bpf_cpumask_release(prev);

		err = 3;

		return 0;

	}



	bpf_rcu_read_lock();

	local = global_mask;

	if (!local) {

		err = 4;

		bpf_rcu_read_unlock();

		return 0;

	}



	bpf_rcu_read_unlock();



	/* RCU region is exited before calling KF_RCU kfunc. */



	bpf_cpumask_test_cpu(0, (const struct cpumask *)local);



	return 0;

}



SEC("tp_btf/task_newtask")

__failure __msg("NULL pointer passed to trusted arg1")

int BPF_PROG(test_global_mask_no_null_check, struct task_struct *task, u64 clone_flags)

{

	struct bpf_cpumask *local, *prev;



	local = create_cpumask();

	if (!local)

		return 0;



	prev = bpf_kptr_xchg(&global_mask, local);

	if (prev) {

		bpf_cpumask_release(prev);

		err = 3;

		return 0;

	}



	bpf_rcu_read_lock();

	local = global_mask;



	/* No NULL check is performed on global cpumask kptr. */

	bpf_cpumask_test_cpu(0, (const struct cpumask *)local);



	bpf_rcu_read_unlock();



	return 0;

}

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

+33 −0
Original line number Diff line number Diff line
@@ -423,3 +423,36 @@ int BPF_PROG(test_insert_kptr_get_release, struct task_struct *task, u64 clone_f 


	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(test_global_mask_rcu, struct task_struct *task, u64 clone_flags)

{

	struct bpf_cpumask *local, *prev;



	if (!is_test_task())

		return 0;



	local = create_cpumask();

	if (!local)

		return 0;



	prev = bpf_kptr_xchg(&global_mask, local);

	if (prev) {

		bpf_cpumask_release(prev);

		err = 3;

		return 0;

	}



	bpf_rcu_read_lock();

	local = global_mask;

	if (!local) {

		err = 4;

		bpf_rcu_read_unlock();

		return 0;

	}



	bpf_cpumask_test_cpu(0, (const struct cpumask *)local);

	bpf_rcu_read_unlock();



	return 0;

}