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selftests/bpf: Add bpf_iter test with bpf_get_task_stack()

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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: bpf_iter test as-is doesn't print the contents of the seq_file. To
see the example above, it is necessary to add printf() to do_dummy_read.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200630062846.664389-5-songliubraving@fb.com
This commit is contained in:
Song Liu 2020-06-29 23:28:46 -07:00 committed by Alexei Starovoitov
parent 2df6bb5493
commit c7568114bc
2 changed files with 54 additions and 0 deletions
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17
tools/testing/selftests/bpf/prog_tests/bpf_iter.c
View File

@ -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"))

37
tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c Normal file
View File

@ -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;
}