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Date: Sun, 28 Jun 2020 22:55:30 -0700
From: Song Liu <songliubraving@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
CC: <peterz@...radead.org>, <ast@...nel.org>, <daniel@...earbox.net>,
<kernel-team@...com>, <john.fastabend@...il.com>,
<kpsingh@...omium.org>, Song Liu <songliubraving@...com>
Subject: [PATCH v4 bpf-next 4/4] selftests/bpf: add bpf_iter test with bpf_get_task_stack()
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.
Signed-off-by: Song Liu <songliubraving@...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;
+}
--
2.24.1
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