[PATCH bpf-next 2/2] selftests/bpf: Add test for sleepable program tailcalls
From: Jiri Olsa <jolsa@kernel.org>
Date: 2026-01-30 08:12:40
Also in:
linux-perf-users
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Linus Torvalds
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: Jiri Olsa <jolsa@kernel.org> --- .../selftests/bpf/prog_tests/tailcalls.c | 74 +++++++++++++++++++ .../selftests/bpf/progs/tailcall_sleepable.c | 43 +++++++++++ 2 files changed, 117 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/tailcall_sleepable.c
diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
index 0ab36503c3b2..7d534fde0af9 100644
--- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
+++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c@@ -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(); }
diff --git a/tools/testing/selftests/bpf/progs/tailcall_sleepable.c b/tools/testing/selftests/bpf/progs/tailcall_sleepable.c
new file mode 100644
index 000000000000..d959a9eaaa9c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_sleepable.c@@ -0,0 +1,43 @@ +// 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";
--
2.52.0