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selftests/bpf: Use both hrtimer enqueue helpers in vmlinux test

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The vmlinux selftest triggers nanosleep and checks that both kprobe
and fentry programs observe the hrtimer enqueue path.

After the hrtimer_start_expires_user() conversion [1], nanosleep
reaches hrtimer_start_range_ns_user() instead of
hrtimer_start_range_ns(). Hard-coding either symbol makes the test
fail either on bpf tree or on linux-next [2].

Update the test to resolve the target symbol at runtime via
libbpf_find_vmlinux_btf_id(). This is a nice example of how to modify
a BPF program to work on both older and newer kernel revision.

[1] https://lore.kernel.org/all/20260408114952.062400833@kernel.org/
[2] https://github.com/kernel-patches/bpf/actions/runs/25485909958/job/74782902203

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20260509005730.250956-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Ihor Solodrai 2026-05-08 17:57:30 -07:00 committed by Alexei Starovoitov
parent a982dda833
commit 25bb05dd06
2 changed files with 45 additions and 4 deletions
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45
tools/testing/selftests/bpf/prog_tests/vmlinux.c
View File

@ -14,21 +14,61 @@ static void nsleep()
(void)syscall(__NR_nanosleep, &ts, NULL);
}
static const char *hrtimer_func = "hrtimer_start_range_ns";
static int setup_hrtimer_progs(struct test_vmlinux *skel)
{
int err;
if (libbpf_find_vmlinux_btf_id("hrtimer_start_range_ns_user", BPF_TRACE_FENTRY) > 0)
hrtimer_func = "hrtimer_start_range_ns_user";
err = bpf_program__set_attach_target(skel->progs.handle__fentry, 0, hrtimer_func);
if (err)
return err;
/*
* Bare SEC("kprobe") has no target function, so attach it manually
* later after selecting the hrtimer function to probe.
*/
bpf_program__set_autoattach(skel->progs.handle__kprobe, false);
return 0;
}
void test_vmlinux(void)
{
int err;
struct test_vmlinux* skel;
struct test_vmlinux__bss *bss;
struct bpf_link *kprobe_link = NULL;
skel = test_vmlinux__open_and_load();
if (!ASSERT_OK_PTR(skel, "test_vmlinux__open_and_load"))
skel = test_vmlinux__open();
if (!ASSERT_OK_PTR(skel, "test_vmlinux__open"))
return;
err = setup_hrtimer_progs(skel);
if (!ASSERT_OK(err, "setup_hrtimer_progs"))
goto cleanup;
err = test_vmlinux__load(skel);
if (!ASSERT_OK(err, "test_vmlinux__load"))
goto cleanup;
bss = skel->bss;
err = test_vmlinux__attach(skel);
if (!ASSERT_OK(err, "test_vmlinux__attach"))
goto cleanup;
/* manually attach kprobe with the selected function */
if (hrtimer_func) {
kprobe_link = bpf_program__attach_kprobe(skel->progs.handle__kprobe,
false /* retprobe */, hrtimer_func);
if (!ASSERT_OK_PTR(kprobe_link, "bpf_program__attach_kprobe"))
goto cleanup;
}
/* trigger everything */
nsleep();
@ -39,5 +79,6 @@ void test_vmlinux(void)
ASSERT_TRUE(bss->fentry_called, "fentry");
cleanup:
bpf_link__destroy(kprobe_link);
test_vmlinux__destroy(skel);
}

4
tools/testing/selftests/bpf/progs/test_vmlinux.c
View File

@ -69,7 +69,7 @@ int BPF_PROG(handle__tp_btf, struct pt_regs *regs, long id)
return 0;
}
SEC("kprobe/hrtimer_start_range_ns")
SEC("kprobe")
int BPF_KPROBE(handle__kprobe, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
const enum hrtimer_mode mode)
{
@ -78,7 +78,7 @@ int BPF_KPROBE(handle__kprobe, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
return 0;
}
SEC("fentry/hrtimer_start_range_ns")
SEC("fentry")
int BPF_PROG(handle__fentry, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
const enum hrtimer_mode mode)
{