* [PATCH bpf v1] selftests/bpf: Use both hrtimer enqueue helpers in vmlinux test
@ 2026-05-07 11:39 Ihor Solodrai
2026-05-07 14:00 ` Amery Hung
0 siblings, 1 reply; 2+ messages in thread
From: Ihor Solodrai @ 2026-05-07 11:39 UTC (permalink / raw)
To: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Kumar Kartikeya Dwivedi
Cc: Thomas Gleixner, bpf
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].
Keep both hook variants as optional BPF programs and enable the pair
matching the running kernel before loading the object. This is also 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>
---
.../selftests/bpf/prog_tests/vmlinux.c | 26 +++++++++++++++++--
.../selftests/bpf/progs/test_vmlinux.c | 22 ++++++++++++++--
2 files changed, 44 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/vmlinux.c b/tools/testing/selftests/bpf/prog_tests/vmlinux.c
index 6fb2217d940b..286feff31488 100644
--- a/tools/testing/selftests/bpf/prog_tests/vmlinux.c
+++ b/tools/testing/selftests/bpf/prog_tests/vmlinux.c
@@ -14,15 +14,37 @@ static void nsleep()
(void)syscall(__NR_nanosleep, &ts, NULL);
}
+static void enable_hrtimer_progs(struct test_vmlinux *skel)
+{
+ bool has_user_helper;
+
+ has_user_helper = libbpf_find_vmlinux_btf_id("hrtimer_start_range_ns_user",
+ BPF_TRACE_FENTRY) > 0;
+ if (has_user_helper) {
+ bpf_program__set_autoload(skel->progs.handle__kprobe_user, true);
+ bpf_program__set_autoload(skel->progs.handle__fentry_user, true);
+ } else {
+ bpf_program__set_autoload(skel->progs.handle__kprobe, true);
+ bpf_program__set_autoload(skel->progs.handle__fentry, true);
+ }
+}
+
void test_vmlinux(void)
{
int err;
struct test_vmlinux* skel;
struct test_vmlinux__bss *bss;
- 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;
+
+ enable_hrtimer_progs(skel);
+
+ err = test_vmlinux__load(skel);
+ if (!ASSERT_OK(err, "test_vmlinux__load"))
+ goto cleanup;
+
bss = skel->bss;
err = test_vmlinux__attach(skel);
diff --git a/tools/testing/selftests/bpf/progs/test_vmlinux.c b/tools/testing/selftests/bpf/progs/test_vmlinux.c
index 78b23934d9f8..c90f7ac63f91 100644
--- a/tools/testing/selftests/bpf/progs/test_vmlinux.c
+++ b/tools/testing/selftests/bpf/progs/test_vmlinux.c
@@ -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/hrtimer_start_range_ns")
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/hrtimer_start_range_ns")
int BPF_PROG(handle__fentry, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
const enum hrtimer_mode mode)
{
@@ -87,4 +87,22 @@ int BPF_PROG(handle__fentry, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
return 0;
}
+SEC("?kprobe/hrtimer_start_range_ns_user")
+int BPF_KPROBE(handle__kprobe_user, struct hrtimer *timer, ktime_t tim,
+ u64 delta_ns, const enum hrtimer_mode mode)
+{
+ if (tim == MY_TV_NSEC)
+ kprobe_called = true;
+ return 0;
+}
+
+SEC("?fentry/hrtimer_start_range_ns_user")
+int BPF_PROG(handle__fentry_user, struct hrtimer *timer, ktime_t tim,
+ u64 delta_ns, const enum hrtimer_mode mode)
+{
+ if (tim == MY_TV_NSEC)
+ fentry_called = true;
+ return 0;
+}
+
char _license[] SEC("license") = "GPL";
--
2.54.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH bpf v1] selftests/bpf: Use both hrtimer enqueue helpers in vmlinux test
2026-05-07 11:39 [PATCH bpf v1] selftests/bpf: Use both hrtimer enqueue helpers in vmlinux test Ihor Solodrai
@ 2026-05-07 14:00 ` Amery Hung
0 siblings, 0 replies; 2+ messages in thread
From: Amery Hung @ 2026-05-07 14:00 UTC (permalink / raw)
To: Ihor Solodrai
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Kumar Kartikeya Dwivedi, Thomas Gleixner, bpf
On Thu, May 7, 2026 at 12:43 PM Ihor Solodrai <ihor.solodrai@linux.dev> wrote:
>
> 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].
>
> Keep both hook variants as optional BPF programs and enable the pair
> matching the running kernel before loading the object. This is also a
> nice example of how to modify a BPF program to work on both older and
> newer kernel revision.
Nice. Can you further use bpf_program__set_attach_target() to avoid
duplicating the program as an example?
>
> [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>
> ---
> .../selftests/bpf/prog_tests/vmlinux.c | 26 +++++++++++++++++--
> .../selftests/bpf/progs/test_vmlinux.c | 22 ++++++++++++++--
> 2 files changed, 44 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/vmlinux.c b/tools/testing/selftests/bpf/prog_tests/vmlinux.c
> index 6fb2217d940b..286feff31488 100644
> --- a/tools/testing/selftests/bpf/prog_tests/vmlinux.c
> +++ b/tools/testing/selftests/bpf/prog_tests/vmlinux.c
> @@ -14,15 +14,37 @@ static void nsleep()
> (void)syscall(__NR_nanosleep, &ts, NULL);
> }
>
> +static void enable_hrtimer_progs(struct test_vmlinux *skel)
> +{
> + bool has_user_helper;
> +
> + has_user_helper = libbpf_find_vmlinux_btf_id("hrtimer_start_range_ns_user",
> + BPF_TRACE_FENTRY) > 0;
> + if (has_user_helper) {
> + bpf_program__set_autoload(skel->progs.handle__kprobe_user, true);
> + bpf_program__set_autoload(skel->progs.handle__fentry_user, true);
> + } else {
> + bpf_program__set_autoload(skel->progs.handle__kprobe, true);
> + bpf_program__set_autoload(skel->progs.handle__fentry, true);
> + }
> +}
> +
> void test_vmlinux(void)
> {
> int err;
> struct test_vmlinux* skel;
> struct test_vmlinux__bss *bss;
>
> - 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;
> +
> + enable_hrtimer_progs(skel);
> +
> + err = test_vmlinux__load(skel);
> + if (!ASSERT_OK(err, "test_vmlinux__load"))
> + goto cleanup;
> +
> bss = skel->bss;
>
> err = test_vmlinux__attach(skel);
> diff --git a/tools/testing/selftests/bpf/progs/test_vmlinux.c b/tools/testing/selftests/bpf/progs/test_vmlinux.c
> index 78b23934d9f8..c90f7ac63f91 100644
> --- a/tools/testing/selftests/bpf/progs/test_vmlinux.c
> +++ b/tools/testing/selftests/bpf/progs/test_vmlinux.c
> @@ -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/hrtimer_start_range_ns")
> 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/hrtimer_start_range_ns")
> int BPF_PROG(handle__fentry, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
> const enum hrtimer_mode mode)
> {
> @@ -87,4 +87,22 @@ int BPF_PROG(handle__fentry, struct hrtimer *timer, ktime_t tim, u64 delta_ns,
> return 0;
> }
>
> +SEC("?kprobe/hrtimer_start_range_ns_user")
> +int BPF_KPROBE(handle__kprobe_user, struct hrtimer *timer, ktime_t tim,
> + u64 delta_ns, const enum hrtimer_mode mode)
> +{
> + if (tim == MY_TV_NSEC)
> + kprobe_called = true;
> + return 0;
> +}
> +
> +SEC("?fentry/hrtimer_start_range_ns_user")
> +int BPF_PROG(handle__fentry_user, struct hrtimer *timer, ktime_t tim,
> + u64 delta_ns, const enum hrtimer_mode mode)
> +{
> + if (tim == MY_TV_NSEC)
> + fentry_called = true;
> + return 0;
> +}
> +
> char _license[] SEC("license") = "GPL";
> --
> 2.54.0
>
>
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2026-05-07 11:39 [PATCH bpf v1] selftests/bpf: Use both hrtimer enqueue helpers in vmlinux test Ihor Solodrai
2026-05-07 14:00 ` Amery Hung
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