Re: [PATCH bpf-next v3 4/4] selftests/bpf: Add tests for sleepable raw tracepoint programs

[Puranjay Mohan <puranjay@kernel.org>]

Mykyta Yatsenko <mykyta.yatsenko5@gmail.com> writes:

> From: Mykyta Yatsenko <yatsenko@meta.com>
>
> Add tests for sleepable raw tracepoint programs:
> - success: Attach a sleepable BPF program to the faultable sys_enter
>   tracepoint (tp_btf.s/sys_enter). Verify the program is triggered by
>   a syscall.
> - reject_non_faultable: Verify that loading a sleepable BPF program
>   targeting a non-faultable tracepoint (tp_btf.s/sched_switch) is
>   rejected by the verifier.
>
> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>

Acked-by: Puranjay Mohan <puranjay@kernel.org>

> ---
>  .../selftests/bpf/prog_tests/sleepable_raw_tp.c    | 40 ++++++++++++++++++++
>  .../selftests/bpf/progs/test_sleepable_raw_tp.c    | 43 ++++++++++++++++++++++
>  .../bpf/progs/test_sleepable_raw_tp_fail.c         | 18 +++++++++
>  tools/testing/selftests/bpf/verifier/sleepable.c   | 17 ++++++++-
>  4 files changed, 116 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/sleepable_raw_tp.c b/tools/testing/selftests/bpf/prog_tests/sleepable_raw_tp.c
> new file mode 100644
> index 000000000000..e902b41591e7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/sleepable_raw_tp.c
> @@ -0,0 +1,40 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
> +
> +#include <test_progs.h>
> +#include <time.h>
> +#include "test_sleepable_raw_tp.skel.h"
> +#include "test_sleepable_raw_tp_fail.skel.h"
> +
> +static void test_sleepable_raw_tp_success(void)
> +{
> +	struct test_sleepable_raw_tp *skel;
> +	int err;
> +
> +	skel = test_sleepable_raw_tp__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "skel_open_load"))
> +		return;
> +
> +	skel->bss->target_pid = getpid();
> +
> +	err = test_sleepable_raw_tp__attach(skel);
> +	if (!ASSERT_OK(err, "skel_attach"))
> +		goto cleanup;
> +
> +	syscall(__NR_nanosleep, &(struct timespec){ .tv_nsec = 555 }, NULL);
> +
> +	ASSERT_EQ(skel->bss->triggered, 1, "triggered");
> +	ASSERT_EQ(skel->bss->err, 0, "err");
> +	ASSERT_EQ(skel->bss->copied_tv_nsec, 555, "copied_tv_nsec");
> +
> +cleanup:
> +	test_sleepable_raw_tp__destroy(skel);
> +}
> +
> +void test_sleepable_raw_tp(void)
> +{
> +	if (test__start_subtest("success"))
> +		test_sleepable_raw_tp_success();
> +
> +	RUN_TESTS(test_sleepable_raw_tp_fail);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_sleepable_raw_tp.c b/tools/testing/selftests/bpf/progs/test_sleepable_raw_tp.c
> new file mode 100644
> index 000000000000..ebacc766df57
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_sleepable_raw_tp.c
> @@ -0,0 +1,43 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
> +
> +#include <vmlinux.h>
> +#include <asm/unistd.h>
> +#include <bpf/bpf_tracing.h>
> +#include <bpf/bpf_core_read.h>
> +#include <bpf/bpf_helpers.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +int target_pid;
> +int triggered;
> +long err;
> +long copied_tv_nsec;
> +
> +SEC("tp_btf.s/sys_enter")
> +int BPF_PROG(test_sleepable_sys_enter, struct pt_regs *regs, long id)
> +{
> +	struct task_struct *task = bpf_get_current_task_btf();
> +	struct __kernel_timespec *ts;
> +	long tv_nsec;
> +
> +	if (task->pid != target_pid)
> +		return 0;
> +
> +	if (id != __NR_nanosleep)
> +		return 0;
> +
> +	ts = (void *)PT_REGS_PARM1_CORE_SYSCALL(regs);
> +
> +	/*
> +	 * Use bpf_copy_from_user() - a sleepable helper - to read user memory.
> +	 * This exercises the sleepable execution path of raw tracepoints.
> +	 */
> +	err = bpf_copy_from_user(&tv_nsec, sizeof(tv_nsec), &ts->tv_nsec);
> +	if (err)
> +		return err;
> +
> +	copied_tv_nsec = tv_nsec;
> +	triggered = 1;
> +	return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_sleepable_raw_tp_fail.c b/tools/testing/selftests/bpf/progs/test_sleepable_raw_tp_fail.c
> new file mode 100644
> index 000000000000..54100899f728
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_sleepable_raw_tp_fail.c
> @@ -0,0 +1,18 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
> +
> +#include <vmlinux.h>
> +#include <bpf/bpf_tracing.h>
> +#include <bpf/bpf_helpers.h>
> +#include "bpf_misc.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +/* Sleepable program on a non-faultable tracepoint should fail to load */
> +SEC("tp_btf.s/sched_switch")
> +__failure __msg("Sleepable program cannot attach to non-faultable tracepoint")
> +int BPF_PROG(test_sleepable_sched_switch, bool preempt,
> +	     struct task_struct *prev, struct task_struct *next)
> +{
> +	return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/verifier/sleepable.c b/tools/testing/selftests/bpf/verifier/sleepable.c
> index 1f0d2bdc673f..6dabc5522945 100644
> --- a/tools/testing/selftests/bpf/verifier/sleepable.c
> +++ b/tools/testing/selftests/bpf/verifier/sleepable.c
> @@ -76,7 +76,20 @@
>  	.runs = -1,
>  },
>  {
> -	"sleepable raw tracepoint reject",
> +	"sleepable raw tracepoint accept",
> +	.insns = {
> +	BPF_MOV64_IMM(BPF_REG_0, 0),
> +	BPF_EXIT_INSN(),
> +	},
> +	.prog_type = BPF_PROG_TYPE_TRACING,
> +	.expected_attach_type = BPF_TRACE_RAW_TP,
> +	.kfunc = "sys_enter",
> +	.result = ACCEPT,
> +	.flags = BPF_F_SLEEPABLE,
> +	.runs = -1,
> +},
> +{
> +	"sleepable raw tracepoint reject non-faultable",
>  	.insns = {
>  	BPF_MOV64_IMM(BPF_REG_0, 0),
>  	BPF_EXIT_INSN(),
> @@ -85,7 +98,7 @@
>  	.expected_attach_type = BPF_TRACE_RAW_TP,
>  	.kfunc = "sched_switch",
>  	.result = REJECT,
> -	.errstr = "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable",
> +	.errstr = "Sleepable program cannot attach to non-faultable tracepoint",
>  	.flags = BPF_F_SLEEPABLE,
>  	.runs = -1,
>  },
>
> -- 
> 2.52.0