BPF Archive on lore.kernel.org
 help / color / Atom feed
From: Yonghong Song <yhs@fb.com>
To: Song Liu <songliubraving@fb.com>, <bpf@vger.kernel.org>,
	<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: <peterz@infradead.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
	<kernel-team@fb.com>, <john.fastabend@gmail.com>,
	<kpsingh@chromium.org>
Subject: Re: [PATCH v4 bpf-next 4/4] selftests/bpf: add bpf_iter test with bpf_get_task_stack()
Date: Mon, 29 Jun 2020 08:06:49 -0700
Message-ID: <bd62a752-df45-8e65-9f74-e340ef708764@fb.com> (raw)
In-Reply-To: <20200629055530.3244342-5-songliubraving@fb.com>



On 6/28/20 10:55 PM, Song Liu wrote:
> The new test is similar to other bpf_iter tests. It dumps all
> /proc/<pid>/stack to a seq_file. Here is some example output:
> 
> pid:     2873 num_entries:        3
> [<0>] worker_thread+0xc6/0x380
> [<0>] kthread+0x135/0x150
> [<0>] ret_from_fork+0x22/0x30
> 
> pid:     2874 num_entries:        9
> [<0>] __bpf_get_stack+0x15e/0x250
> [<0>] bpf_prog_22a400774977bb30_dump_task_stack+0x4a/0xb3c
> [<0>] bpf_iter_run_prog+0x81/0x170
> [<0>] __task_seq_show+0x58/0x80
> [<0>] bpf_seq_read+0x1c3/0x3b0
> [<0>] vfs_read+0x9e/0x170
> [<0>] ksys_read+0xa7/0xe0
> [<0>] do_syscall_64+0x4c/0xa0
> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Note: To print the output, it is necessary to modify the selftest.

I do not know what this sentence means. It seems confusing
and probably not needed.

> 
> Signed-off-by: Song Liu <songliubraving@fb.com>

Acked-by: Yonghong Song <yhs@fb.com>

> ---
>   .../selftests/bpf/prog_tests/bpf_iter.c       | 17 +++++++++
>   .../selftests/bpf/progs/bpf_iter_task_stack.c | 37 +++++++++++++++++++
>   2 files changed, 54 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> index 1e2e0fced6e81..fed42755416db 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> @@ -5,6 +5,7 @@
>   #include "bpf_iter_netlink.skel.h"
>   #include "bpf_iter_bpf_map.skel.h"
>   #include "bpf_iter_task.skel.h"
> +#include "bpf_iter_task_stack.skel.h"
>   #include "bpf_iter_task_file.skel.h"
>   #include "bpf_iter_tcp4.skel.h"
>   #include "bpf_iter_tcp6.skel.h"
> @@ -110,6 +111,20 @@ static void test_task(void)
>   	bpf_iter_task__destroy(skel);
>   }
>   
> +static void test_task_stack(void)
> +{
> +	struct bpf_iter_task_stack *skel;
> +
> +	skel = bpf_iter_task_stack__open_and_load();
> +	if (CHECK(!skel, "bpf_iter_task_stack__open_and_load",
> +		  "skeleton open_and_load failed\n"))
> +		return;
> +
> +	do_dummy_read(skel->progs.dump_task_stack);
> +
> +	bpf_iter_task_stack__destroy(skel);
> +}
> +
>   static void test_task_file(void)
>   {
>   	struct bpf_iter_task_file *skel;
> @@ -452,6 +467,8 @@ void test_bpf_iter(void)
>   		test_bpf_map();
>   	if (test__start_subtest("task"))
>   		test_task();
> +	if (test__start_subtest("task_stack"))
> +		test_task_stack();
>   	if (test__start_subtest("task_file"))
>   		test_task_file();
>   	if (test__start_subtest("tcp4"))
> diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
> new file mode 100644
> index 0000000000000..e40d32a2ed93d
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
> @@ -0,0 +1,37 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Facebook */
> +#include "bpf_iter.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +#define MAX_STACK_TRACE_DEPTH   64
> +unsigned long entries[MAX_STACK_TRACE_DEPTH];
> +#define SIZE_OF_ULONG (sizeof(unsigned long))
> +
> +SEC("iter/task")
> +int dump_task_stack(struct bpf_iter__task *ctx)
> +{
> +	struct seq_file *seq = ctx->meta->seq;
> +	struct task_struct *task = ctx->task;
> +	long i, retlen;
> +
> +	if (task == (void *)0)
> +		return 0;
> +
> +	retlen = bpf_get_task_stack(task, entries,
> +				    MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, 0);
> +	if (retlen < 0)
> +		return 0;
> +
> +	BPF_SEQ_PRINTF(seq, "pid: %8u num_entries: %8u\n", task->pid,
> +		       retlen / SIZE_OF_ULONG);
> +	for (i = 0; i < MAX_STACK_TRACE_DEPTH; i++) {
> +		if (retlen > i * SIZE_OF_ULONG)
> +			BPF_SEQ_PRINTF(seq, "[<0>] %pB\n", (void *)entries[i]);
> +	}
> +	BPF_SEQ_PRINTF(seq, "\n");
> +
> +	return 0;
> +}
> 

  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29  5:55 [PATCH v4 bpf-next 0/4] bpf: introduce bpf_get_task_stack() Song Liu
2020-06-29  5:55 ` [PATCH v4 bpf-next 1/4] perf: expose get/put_callchain_entry() Song Liu
2020-06-29  5:55 ` [PATCH v4 bpf-next 2/4] bpf: introduce helper bpf_get_task_stack() Song Liu
2020-06-30  4:18   ` Alexei Starovoitov
2020-06-30  6:12     ` Song Liu
2020-06-29  5:55 ` [PATCH v4 bpf-next 3/4] bpf: allow %pB in bpf_seq_printf() and bpf_trace_printk() Song Liu
2020-06-29  5:55 ` [PATCH v4 bpf-next 4/4] selftests/bpf: add bpf_iter test with bpf_get_task_stack() Song Liu
2020-06-29 15:06   ` Yonghong Song [this message]
2020-06-29 16:56     ` Song Liu
2020-06-29 18:22       ` Yonghong Song
2020-06-29 19:25 ` [PATCH v4 bpf-next 0/4] bpf: introduce bpf_get_task_stack() Andrii Nakryiko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=bd62a752-df45-8e65-9f74-e340ef708764@fb.com \
    --to=yhs@fb.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=john.fastabend@gmail.com \
    --cc=kernel-team@fb.com \
    --cc=kpsingh@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=peterz@infradead.org \
    --cc=songliubraving@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 bpf bpf/ https://lore.kernel.org/bpf \
		bpf@vger.kernel.org
	public-inbox-index bpf

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.bpf


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git