Commit 15ac1adf authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add test for sleepable program tailcalls 



Adding test that makes sure we can't mix sleepable and non-sleepable
bpf programs in the BPF_MAP_TYPE_PROG_ARRAY map and that we can do
tail call in the sleepable program.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20260130081208.1130204-3-jolsa@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0f0c3329

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

+74 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include "tailcall_freplace.skel.h"

#include "tc_bpf2bpf.skel.h"

#include "tailcall_fail.skel.h"

#include "tailcall_sleepable.skel.h"



/* test_tailcall_1 checks basic functionality by patching multiple locations

 * in a single program for a single tail call slot with nop->jmp, jmp->nop
@@ -1653,6 +1654,77 @@ static void test_tailcall_failure() 
	RUN_TESTS(tailcall_fail);

}



noinline void uprobe_sleepable_trigger(void)

{

	asm volatile ("");

}



static void test_tailcall_sleepable(void)

{

	LIBBPF_OPTS(bpf_uprobe_opts, opts);

	struct tailcall_sleepable *skel;

	int prog_fd, map_fd;

	int err, key;



	skel = tailcall_sleepable__open();

	if (!ASSERT_OK_PTR(skel, "tailcall_sleepable__open"))

		return;



	/*

	 * Test that we can't load uprobe_normal and uprobe_sleepable_1,

	 * because they share tailcall map.

	 */

	bpf_program__set_autoload(skel->progs.uprobe_normal, true);

	bpf_program__set_autoload(skel->progs.uprobe_sleepable_1, true);



	err = tailcall_sleepable__load(skel);

	if (!ASSERT_ERR(err, "tailcall_sleepable__load"))

		goto out;



	tailcall_sleepable__destroy(skel);



	/*

	 * Test that we can tail call from sleepable to sleepable program.

	 */

	skel = tailcall_sleepable__open();

	if (!ASSERT_OK_PTR(skel, "tailcall_sleepable__open"))

		return;



	bpf_program__set_autoload(skel->progs.uprobe_sleepable_1, true);

	bpf_program__set_autoload(skel->progs.uprobe_sleepable_2, true);



	err = tailcall_sleepable__load(skel);

	if (!ASSERT_OK(err, "tailcall_sleepable__load"))

		goto out;



	/* Add sleepable uprobe_sleepable_2 to jmp_table[0]. */

	key = 0;

	prog_fd = bpf_program__fd(skel->progs.uprobe_sleepable_2);

	map_fd = bpf_map__fd(skel->maps.jmp_table);

	err = bpf_map_update_elem(map_fd, &key, &prog_fd, BPF_ANY);

	if (!ASSERT_OK(err, "update jmp_table"))

		goto out;



	skel->bss->my_pid = getpid();



	/* Attach uprobe_sleepable_1 to uprobe_sleepable_trigger and hit it.  */

	opts.func_name = "uprobe_sleepable_trigger";

	skel->links.uprobe_sleepable_1 = bpf_program__attach_uprobe_opts(

						skel->progs.uprobe_sleepable_1,

						-1,

						"/proc/self/exe",

						0 /* offset */,

						&opts);

	if (!ASSERT_OK_PTR(skel->links.uprobe_sleepable_1, "bpf_program__attach_uprobe_opts"))

		goto out;



	uprobe_sleepable_trigger();

	ASSERT_EQ(skel->bss->executed, 1, "executed");



out:

	tailcall_sleepable__destroy(skel);

}



void test_tailcalls(void)

{

	if (test__start_subtest("tailcall_1"))
@@ -1707,4 +1779,6 @@ void test_tailcalls(void) 
		test_tailcall_bpf2bpf_freplace();

	if (test__start_subtest("tailcall_failure"))

		test_tailcall_failure();

	if (test__start_subtest("tailcall_sleepable"))

		test_tailcall_sleepable();

}

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

0 → 100644
+43 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"

#include "bpf_test_utils.h"



struct {

	__uint(type, BPF_MAP_TYPE_PROG_ARRAY);

	__uint(max_entries, 1);

	__uint(key_size, sizeof(__u32));

	__array(values, void (void));

} jmp_table SEC(".maps");



SEC("?uprobe")

int uprobe_normal(void *ctx)

{

	bpf_tail_call_static(ctx, &jmp_table, 0);

	return 0;

}



SEC("?uprobe.s")

int uprobe_sleepable_1(void *ctx)

{

	bpf_tail_call_static(ctx, &jmp_table, 0);

	return 0;

}



int executed = 0;

int my_pid = 0;



SEC("?uprobe.s")

int uprobe_sleepable_2(void *ctx)

{

	int pid = bpf_get_current_pid_tgid() >> 32;



	if (pid != my_pid)

		return 0;



	executed++;

	return 0;

}



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