diff mbox series

[bpf-next,v4,21/21] tools/bpf: selftests: add bpf_iter selftests

Message ID 20200509175923.2477637-1-yhs@fb.com
State Accepted
Delegated to: BPF Maintainers
Headers show
Series bpf: implement bpf iterator for kernel data | expand

Commit Message

Yonghong Song May 9, 2020, 5:59 p.m. UTC 
The added test includes the following subtests:
  - test verifier change for btf_id_or_null
  - test load/create_iter/read for
    ipv6_route/netlink/bpf_map/task/task_file
  - test anon bpf iterator
  - test anon bpf iterator reading one char at a time
  - test file bpf iterator
  - test overflow (single bpf program output not overflow)
  - test overflow (single bpf program output overflows)
  - test bpf prog returning 1

The ipv6_route tests the following verifier change
  - access fields in the variable length array of the structure.

The netlink load tests the following verifier change
  - put a btf_id ptr value in a stack and accessible to
    tracing/iter programs.

The anon bpf iterator also tests link auto attach through skeleton.

  $ test_progs -n 2
  #2/1 btf_id_or_null:OK
  #2/2 ipv6_route:OK
  #2/3 netlink:OK
  #2/4 bpf_map:OK
  #2/5 task:OK
  #2/6 task_file:OK
  #2/7 anon:OK
  #2/8 anon-read-one-char:OK
  #2/9 file:OK
  #2/10 overflow:OK
  #2/11 overflow-e2big:OK
  #2/12 prog-ret-1:OK
  #2 bpf_iter:OK
  Summary: 1/12 PASSED, 0 SKIPPED, 0 FAILED

Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
---
 .../selftests/bpf/prog_tests/bpf_iter.c       | 409 ++++++++++++++++++
 .../selftests/bpf/progs/bpf_iter_test_kern1.c |   4 +
 .../selftests/bpf/progs/bpf_iter_test_kern2.c |   4 +
 .../selftests/bpf/progs/bpf_iter_test_kern3.c |  18 +
 .../selftests/bpf/progs/bpf_iter_test_kern4.c |  52 +++
 .../bpf/progs/bpf_iter_test_kern_common.h     |  22 +
 6 files changed, 509 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_iter.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern1.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern2.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern3.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_test_kern_common.h

Comments

Alexei Starovoitov May 10, 2020, 12:34 a.m. UTC | #1 
On Sat, May 09, 2020 at 10:59:23AM -0700, Yonghong Song wrote:
> +static volatile const __u32 ret1;
> +
> +SEC("iter/bpf_map")
> +int dump_bpf_map(struct bpf_iter__bpf_map *ctx)
> +{
> +	struct seq_file *seq = ctx->meta->seq;
> +	struct bpf_map *map = ctx->map;
> +	__u64 seq_num;
> +	int i, ret = 0;
> +
> +	if (map == (void *)0)
> +		return 0;
> +
> +	/* only dump map1_id and map2_id */
> +	if (map->id != map1_id && map->id != map2_id)
> +		return 0;
> +
> +	seq_num = ctx->meta->seq_num;
> +	if (map->id == map1_id) {
> +		map1_seqnum = seq_num;
> +		map1_accessed++;
> +	}
> +
> +	if (map->id == map2_id) {
> +		if (map2_accessed == 0) {
> +			map2_seqnum1 = seq_num;
> +			if (ret1)
> +				ret = 1;
> +		} else {
> +			map2_seqnum2 = seq_num;
> +		}
> +		map2_accessed++;
> +	}
> +
> +	/* fill seq_file buffer */
> +	for (i = 0; i < print_len; i++)
> +		bpf_seq_write(seq, &seq_num, sizeof(seq_num));
> +
> +	return ret;
> +}

I couldn't find where 'return 1' behavior is documented clearly.
I think it's a workaround for overflow.
When bpf prog detects overflow it can request replay of the element?
What if it keeps returning 1 ? read() will never finish?
Yonghong Song May 10, 2020, 5:01 a.m. UTC | #2 
On 5/9/20 5:34 PM, Alexei Starovoitov wrote:
> On Sat, May 09, 2020 at 10:59:23AM -0700, Yonghong Song wrote:
>> +static volatile const __u32 ret1;
>> +
>> +SEC("iter/bpf_map")
>> +int dump_bpf_map(struct bpf_iter__bpf_map *ctx)
>> +{
>> +	struct seq_file *seq = ctx->meta->seq;
>> +	struct bpf_map *map = ctx->map;
>> +	__u64 seq_num;
>> +	int i, ret = 0;
>> +
>> +	if (map == (void *)0)
>> +		return 0;
>> +
>> +	/* only dump map1_id and map2_id */
>> +	if (map->id != map1_id && map->id != map2_id)
>> +		return 0;
>> +
>> +	seq_num = ctx->meta->seq_num;
>> +	if (map->id == map1_id) {
>> +		map1_seqnum = seq_num;
>> +		map1_accessed++;
>> +	}
>> +
>> +	if (map->id == map2_id) {
>> +		if (map2_accessed == 0) {
>> +			map2_seqnum1 = seq_num;
>> +			if (ret1)
>> +				ret = 1;
>> +		} else {
>> +			map2_seqnum2 = seq_num;
>> +		}
>> +		map2_accessed++;
>> +	}
>> +
>> +	/* fill seq_file buffer */
>> +	for (i = 0; i < print_len; i++)
>> +		bpf_seq_write(seq, &seq_num, sizeof(seq_num));
>> +
>> +	return ret;
>> +}
> 
> I couldn't find where 'return 1' behavior is documented clearly.

It is in the commit comments:

commit 15d83c4d7cef5c067a8b075ce59e97df4f60706e
Author: Yonghong Song <yhs@fb.com>
Date:   Sat May 9 10:59:00 2020 -0700

     bpf: Allow loading of a bpf_iter program
...
     The program return value must be 0 or 1 for now.
       0 : successful, except potential seq_file buffer overflow
           which is handled by seq_file reader.
       1 : request to restart the same object

Internally, bpf program returning 1 will translate
show() return -EAGAIN and this error code will
return to user space.

I will add some comments in the code to
document this behavior.

> I think it's a workaround for overflow.

This can be used for overflow but overflow already been taken
care of by bpf_seq_read(). This is mostly used for other use
cases:
    - currently under RT-linux, bpf_seq_printf() may return
      -EBUSY. In this case, bpf program itself can request
      retrying the same object.
    - for other conditions where bpf program itself wants
      to retry the same object. For example, hash table full,
      the bpf progam can return 1, in which case, user space
      read() will receive -EAGAIN and may check and make room
      for hash table and then read() again.

> When bpf prog detects overflow it can request replay of the element?

It can. But it can return 0 too since bpf_seq_read() handles
this transparently.

> What if it keeps returning 1 ? read() will never finish?

The read() will finish and return -EAGAIN to user space.
It is up to user space to decide whether to call read()
again or not.
Alexei Starovoitov May 10, 2020, 4:14 p.m. UTC | #3 
On Sat, May 9, 2020 at 10:01 PM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 5/9/20 5:34 PM, Alexei Starovoitov wrote:
> > On Sat, May 09, 2020 at 10:59:23AM -0700, Yonghong Song wrote:
> >> +static volatile const __u32 ret1;
> >> +
> >> +SEC("iter/bpf_map")
> >> +int dump_bpf_map(struct bpf_iter__bpf_map *ctx)
> >> +{
> >> +    struct seq_file *seq = ctx->meta->seq;
> >> +    struct bpf_map *map = ctx->map;
> >> +    __u64 seq_num;
> >> +    int i, ret = 0;
> >> +
> >> +    if (map == (void *)0)
> >> +            return 0;
> >> +
> >> +    /* only dump map1_id and map2_id */
> >> +    if (map->id != map1_id && map->id != map2_id)
> >> +            return 0;
> >> +
> >> +    seq_num = ctx->meta->seq_num;
> >> +    if (map->id == map1_id) {
> >> +            map1_seqnum = seq_num;
> >> +            map1_accessed++;
> >> +    }
> >> +
> >> +    if (map->id == map2_id) {
> >> +            if (map2_accessed == 0) {
> >> +                    map2_seqnum1 = seq_num;
> >> +                    if (ret1)
> >> +                            ret = 1;
> >> +            } else {
> >> +                    map2_seqnum2 = seq_num;
> >> +            }
> >> +            map2_accessed++;
> >> +    }
> >> +
> >> +    /* fill seq_file buffer */
> >> +    for (i = 0; i < print_len; i++)
> >> +            bpf_seq_write(seq, &seq_num, sizeof(seq_num));
> >> +
> >> +    return ret;
> >> +}
> >
> > I couldn't find where 'return 1' behavior is documented clearly.
>
> It is in the commit comments:
>
> commit 15d83c4d7cef5c067a8b075ce59e97df4f60706e
> Author: Yonghong Song <yhs@fb.com>
> Date:   Sat May 9 10:59:00 2020 -0700
>
>      bpf: Allow loading of a bpf_iter program
> ...
>      The program return value must be 0 or 1 for now.
>        0 : successful, except potential seq_file buffer overflow
>            which is handled by seq_file reader.
>        1 : request to restart the same object
>
> Internally, bpf program returning 1 will translate
> show() return -EAGAIN and this error code will
> return to user space.
>
> I will add some comments in the code to
> document this behavior.
>
> > I think it's a workaround for overflow.
>
> This can be used for overflow but overflow already been taken
> care of by bpf_seq_read(). This is mostly used for other use
> cases:
>     - currently under RT-linux, bpf_seq_printf() may return
>       -EBUSY. In this case, bpf program itself can request
>       retrying the same object.
>     - for other conditions where bpf program itself wants
>       to retry the same object. For example, hash table full,
>       the bpf progam can return 1, in which case, user space
>       read() will receive -EAGAIN and may check and make room
>       for hash table and then read() again.
>
> > When bpf prog detects overflow it can request replay of the element?
>
> It can. But it can return 0 too since bpf_seq_read() handles
> this transparently.
>
> > What if it keeps returning 1 ? read() will never finish?
>
> The read() will finish and return -EAGAIN to user space.
> It is up to user space to decide whether to call read()
> again or not.

Ahh. Got it. So that EAGAIN returned by bpf_iter_run_prog()
propagates by bpf_seq_read() all the way to read() syscall.
Now I see it. Thanks for explaining.
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
new file mode 100644
index 000000000000..87c29dde1cf9
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -0,0 +1,409 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include <test_progs.h>
+#include "bpf_iter_ipv6_route.skel.h"
+#include "bpf_iter_netlink.skel.h"
+#include "bpf_iter_bpf_map.skel.h"
+#include "bpf_iter_task.skel.h"
+#include "bpf_iter_task_file.skel.h"
+#include "bpf_iter_test_kern1.skel.h"
+#include "bpf_iter_test_kern2.skel.h"
+#include "bpf_iter_test_kern3.skel.h"
+#include "bpf_iter_test_kern4.skel.h"
+
+static int duration;
+
+static void test_btf_id_or_null(void)
+{
+	struct bpf_iter_test_kern3 *skel;
+
+	skel = bpf_iter_test_kern3__open_and_load();
+	if (CHECK(skel, "bpf_iter_test_kern3__open_and_load",
+		  "skeleton open_and_load unexpectedly succeeded\n")) {
+		bpf_iter_test_kern3__destroy(skel);
+		return;
+	}
+}
+
+static void do_dummy_read(struct bpf_program *prog)
+{
+	struct bpf_link *link;
+	char buf[16] = {};
+	int iter_fd, len;
+
+	link = bpf_program__attach_iter(prog, NULL);
+	if (CHECK(IS_ERR(link), "attach_iter", "attach_iter failed\n"))
+		return;
+
+	iter_fd = bpf_iter_create(bpf_link__fd(link));
+	if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))
+		goto free_link;
+
+	/* not check contents, but ensure read() ends without error */
+	while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
+		;
+	CHECK(len < 0, "read", "read failed: %s\n", strerror(errno));
+
+	close(iter_fd);
+
+free_link:
+	bpf_link__destroy(link);
+}
+
+static void test_ipv6_route(void)
+{
+	struct bpf_iter_ipv6_route *skel;
+
+	skel = bpf_iter_ipv6_route__open_and_load();
+	if (CHECK(!skel, "bpf_iter_ipv6_route__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		return;
+
+	do_dummy_read(skel->progs.dump_ipv6_route);
+
+	bpf_iter_ipv6_route__destroy(skel);
+}
+
+static void test_netlink(void)
+{
+	struct bpf_iter_netlink *skel;
+
+	skel = bpf_iter_netlink__open_and_load();
+	if (CHECK(!skel, "bpf_iter_netlink__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		return;
+
+	do_dummy_read(skel->progs.dump_netlink);
+
+	bpf_iter_netlink__destroy(skel);
+}
+
+static void test_bpf_map(void)
+{
+	struct bpf_iter_bpf_map *skel;
+
+	skel = bpf_iter_bpf_map__open_and_load();
+	if (CHECK(!skel, "bpf_iter_bpf_map__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		return;
+
+	do_dummy_read(skel->progs.dump_bpf_map);
+
+	bpf_iter_bpf_map__destroy(skel);
+}
+
+static void test_task(void)
+{
+	struct bpf_iter_task *skel;
+
+	skel = bpf_iter_task__open_and_load();
+	if (CHECK(!skel, "bpf_iter_task__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		return;
+
+	do_dummy_read(skel->progs.dump_task);
+
+	bpf_iter_task__destroy(skel);
+}
+
+static void test_task_file(void)
+{
+	struct bpf_iter_task_file *skel;
+
+	skel = bpf_iter_task_file__open_and_load();
+	if (CHECK(!skel, "bpf_iter_task_file__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		return;
+
+	do_dummy_read(skel->progs.dump_task_file);
+
+	bpf_iter_task_file__destroy(skel);
+}
+
+/* The expected string is less than 16 bytes */
+static int do_read_with_fd(int iter_fd, const char *expected,
+			   bool read_one_char)
+{
+	int err = -1, len, read_buf_len, start;
+	char buf[16] = {};
+
+	read_buf_len = read_one_char ? 1 : 16;
+	start = 0;
+	while ((len = read(iter_fd, buf + start, read_buf_len)) > 0) {
+		start += len;
+		if (CHECK(start >= 16, "read", "read len %d\n", len))
+			return -1;
+		read_buf_len = read_one_char ? 1 : 16 - start;
+	}
+	if (CHECK(len < 0, "read", "read failed: %s\n", strerror(errno)))
+		return -1;
+
+	err = strcmp(buf, expected);
+	if (CHECK(err, "read", "incorrect read result: buf %s, expected %s\n",
+		  buf, expected))
+		return -1;
+
+	return 0;
+}
+
+static void test_anon_iter(bool read_one_char)
+{
+	struct bpf_iter_test_kern1 *skel;
+	struct bpf_link *link;
+	int iter_fd, err;
+
+	skel = bpf_iter_test_kern1__open_and_load();
+	if (CHECK(!skel, "bpf_iter_test_kern1__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		return;
+
+	err = bpf_iter_test_kern1__attach(skel);
+	if (CHECK(err, "bpf_iter_test_kern1__attach",
+		  "skeleton attach failed\n")) {
+		goto out;
+	}
+
+	link = skel->links.dump_task;
+	iter_fd = bpf_iter_create(bpf_link__fd(link));
+	if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))
+		goto out;
+
+	do_read_with_fd(iter_fd, "abcd", read_one_char);
+	close(iter_fd);
+
+out:
+	bpf_iter_test_kern1__destroy(skel);
+}
+
+static int do_read(const char *path, const char *expected)
+{
+	int err, iter_fd;
+
+	iter_fd = open(path, O_RDONLY);
+	if (CHECK(iter_fd < 0, "open", "open %s failed: %s\n",
+		  path, strerror(errno)))
+		return -1;
+
+	err = do_read_with_fd(iter_fd, expected, false);
+	close(iter_fd);
+	return err;
+}
+
+static void test_file_iter(void)
+{
+	const char *path = "/sys/fs/bpf/bpf_iter_test1";
+	struct bpf_iter_test_kern1 *skel1;
+	struct bpf_iter_test_kern2 *skel2;
+	struct bpf_link *link;
+	int err;
+
+	skel1 = bpf_iter_test_kern1__open_and_load();
+	if (CHECK(!skel1, "bpf_iter_test_kern1__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		return;
+
+	link = bpf_program__attach_iter(skel1->progs.dump_task, NULL);
+	if (CHECK(IS_ERR(link), "attach_iter", "attach_iter failed\n"))
+		goto out;
+
+	/* unlink this path if it exists. */
+	unlink(path);
+
+	err = bpf_link__pin(link, path);
+	if (CHECK(err, "pin_iter", "pin_iter to %s failed: %d\n", path, err))
+		goto free_link;
+
+	err = do_read(path, "abcd");
+	if (err)
+		goto unlink_path;
+
+	/* file based iterator seems working fine. Let us a link update
+	 * of the underlying link and `cat` the iterator again, its content
+	 * should change.
+	 */
+	skel2 = bpf_iter_test_kern2__open_and_load();
+	if (CHECK(!skel2, "bpf_iter_test_kern2__open_and_load",
+		  "skeleton open_and_load failed\n"))
+		goto unlink_path;
+
+	err = bpf_link__update_program(link, skel2->progs.dump_task);
+	if (CHECK(err, "update_prog", "update_prog failed\n"))
+		goto destroy_skel2;
+
+	do_read(path, "ABCD");
+
+destroy_skel2:
+	bpf_iter_test_kern2__destroy(skel2);
+unlink_path:
+	unlink(path);
+free_link:
+	bpf_link__destroy(link);
+out:
+	bpf_iter_test_kern1__destroy(skel1);
+}
+
+static void test_overflow(bool test_e2big_overflow, bool ret1)
+{
+	__u32 map_info_len, total_read_len, expected_read_len;
+	int err, iter_fd, map1_fd, map2_fd, len;
+	struct bpf_map_info map_info = {};
+	struct bpf_iter_test_kern4 *skel;
+	struct bpf_link *link;
+	__u32 page_size;
+	char *buf;
+
+	skel = bpf_iter_test_kern4__open();
+	if (CHECK(!skel, "bpf_iter_test_kern4__open",
+		  "skeleton open failed\n"))
+		return;
+
+	/* create two maps: bpf program will only do bpf_seq_write
+	 * for these two maps. The goal is one map output almost
+	 * fills seq_file buffer and then the other will trigger
+	 * overflow and needs restart.
+	 */
+	map1_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, 4, 8, 1, 0);
+	if (CHECK(map1_fd < 0, "bpf_create_map",
+		  "map_creation failed: %s\n", strerror(errno)))
+		goto out;
+	map2_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, 4, 8, 1, 0);
+	if (CHECK(map2_fd < 0, "bpf_create_map",
+		  "map_creation failed: %s\n", strerror(errno)))
+		goto free_map1;
+
+	/* bpf_seq_printf kernel buffer is one page, so one map
+	 * bpf_seq_write will mostly fill it, and the other map
+	 * will partially fill and then trigger overflow and need
+	 * bpf_seq_read restart.
+	 */
+	page_size = sysconf(_SC_PAGE_SIZE);
+
+	if (test_e2big_overflow) {
+		skel->rodata->print_len = (page_size + 8) / 8;
+		expected_read_len = 2 * (page_size + 8);
+	} else if (!ret1) {
+		skel->rodata->print_len = (page_size - 8) / 8;
+		expected_read_len = 2 * (page_size - 8);
+	} else {
+		skel->rodata->print_len = 1;
+		expected_read_len = 2 * 8;
+	}
+	skel->rodata->ret1 = ret1;
+
+	if (CHECK(bpf_iter_test_kern4__load(skel),
+		  "bpf_iter_test_kern4__load", "skeleton load failed\n"))
+		goto free_map2;
+
+	/* setup filtering map_id in bpf program */
+	map_info_len = sizeof(map_info);
+	err = bpf_obj_get_info_by_fd(map1_fd, &map_info, &map_info_len);
+	if (CHECK(err, "get_map_info", "get map info failed: %s\n",
+		  strerror(errno)))
+		goto free_map2;
+	skel->bss->map1_id = map_info.id;
+
+	err = bpf_obj_get_info_by_fd(map2_fd, &map_info, &map_info_len);
+	if (CHECK(err, "get_map_info", "get map info failed: %s\n",
+		  strerror(errno)))
+		goto free_map2;
+	skel->bss->map2_id = map_info.id;
+
+	link = bpf_program__attach_iter(skel->progs.dump_bpf_map, NULL);
+	if (CHECK(IS_ERR(link), "attach_iter", "attach_iter failed\n"))
+		goto free_map2;
+
+	iter_fd = bpf_iter_create(bpf_link__fd(link));
+	if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))
+		goto free_link;
+
+	buf = malloc(expected_read_len);
+	if (!buf)
+		goto close_iter;
+
+	/* do read */
+	total_read_len = 0;
+	if (test_e2big_overflow) {
+		while ((len = read(iter_fd, buf, expected_read_len)) > 0)
+			total_read_len += len;
+
+		CHECK(len != -1 || errno != E2BIG, "read",
+		      "expected ret -1, errno E2BIG, but get ret %d, error %s\n",
+			  len, strerror(errno));
+		goto free_buf;
+	} else if (!ret1) {
+		while ((len = read(iter_fd, buf, expected_read_len)) > 0)
+			total_read_len += len;
+
+		if (CHECK(len < 0, "read", "read failed: %s\n",
+			  strerror(errno)))
+			goto free_buf;
+	} else {
+		do {
+			len = read(iter_fd, buf, expected_read_len);
+			if (len > 0)
+				total_read_len += len;
+		} while (len > 0 || len == -EAGAIN);
+
+		if (CHECK(len < 0, "read", "read failed: %s\n",
+			  strerror(errno)))
+			goto free_buf;
+	}
+
+	if (CHECK(total_read_len != expected_read_len, "read",
+		  "total len %u, expected len %u\n", total_read_len,
+		  expected_read_len))
+		goto free_buf;
+
+	if (CHECK(skel->bss->map1_accessed != 1, "map1_accessed",
+		  "expected 1 actual %d\n", skel->bss->map1_accessed))
+		goto free_buf;
+
+	if (CHECK(skel->bss->map2_accessed != 2, "map2_accessed",
+		  "expected 2 actual %d\n", skel->bss->map2_accessed))
+		goto free_buf;
+
+	CHECK(skel->bss->map2_seqnum1 != skel->bss->map2_seqnum2,
+	      "map2_seqnum", "two different seqnum %lld %lld\n",
+	      skel->bss->map2_seqnum1, skel->bss->map2_seqnum2);
+
+free_buf:
+	free(buf);
+close_iter:
+	close(iter_fd);
+free_link:
+	bpf_link__destroy(link);
+free_map2:
+	close(map2_fd);
+free_map1:
+	close(map1_fd);
+out:
+	bpf_iter_test_kern4__destroy(skel);
+}
+
+void test_bpf_iter(void)
+{
+	if (test__start_subtest("btf_id_or_null"))
+		test_btf_id_or_null();
+	if (test__start_subtest("ipv6_route"))
+		test_ipv6_route();
+	if (test__start_subtest("netlink"))
+		test_netlink();
+	if (test__start_subtest("bpf_map"))
+		test_bpf_map();
+	if (test__start_subtest("task"))
+		test_task();
+	if (test__start_subtest("task_file"))
+		test_task_file();
+	if (test__start_subtest("anon"))
+		test_anon_iter(false);
+	if (test__start_subtest("anon-read-one-char"))
+		test_anon_iter(true);
+	if (test__start_subtest("file"))
+		test_file_iter();
+	if (test__start_subtest("overflow"))
+		test_overflow(false, false);
+	if (test__start_subtest("overflow-e2big"))
+		test_overflow(true, false);
+	if (test__start_subtest("prog-ret-1"))
+		test_overflow(false, true);
+}
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern1.c b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern1.c
new file mode 100644
index 000000000000..c71a7c283108
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern1.c
@@ -0,0 +1,4 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#define START_CHAR 'a'
+#include "bpf_iter_test_kern_common.h"
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern2.c b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern2.c
new file mode 100644
index 000000000000..8bdc8dc07444
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern2.c
@@ -0,0 +1,4 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#define START_CHAR 'A'
+#include "bpf_iter_test_kern_common.h"
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern3.c b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern3.c
new file mode 100644
index 000000000000..636a00fa074d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern3.c
@@ -0,0 +1,18 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("iter/task")
+int dump_task(struct bpf_iter__task *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	struct task_struct *task = ctx->task;
+	int tgid;
+
+	tgid = task->tgid;
+	bpf_seq_write(seq, &tgid, sizeof(tgid));
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c
new file mode 100644
index 000000000000..b18dc0471d07
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern4.c
@@ -0,0 +1,52 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u32 map1_id = 0, map2_id = 0;
+__u32 map1_accessed = 0, map2_accessed = 0;
+__u64 map1_seqnum = 0, map2_seqnum1 = 0, map2_seqnum2 = 0;
+
+static volatile const __u32 print_len;
+static volatile const __u32 ret1;
+
+SEC("iter/bpf_map")
+int dump_bpf_map(struct bpf_iter__bpf_map *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	struct bpf_map *map = ctx->map;
+	__u64 seq_num;
+	int i, ret = 0;
+
+	if (map == (void *)0)
+		return 0;
+
+	/* only dump map1_id and map2_id */
+	if (map->id != map1_id && map->id != map2_id)
+		return 0;
+
+	seq_num = ctx->meta->seq_num;
+	if (map->id == map1_id) {
+		map1_seqnum = seq_num;
+		map1_accessed++;
+	}
+
+	if (map->id == map2_id) {
+		if (map2_accessed == 0) {
+			map2_seqnum1 = seq_num;
+			if (ret1)
+				ret = 1;
+		} else {
+			map2_seqnum2 = seq_num;
+		}
+		map2_accessed++;
+	}
+
+	/* fill seq_file buffer */
+	for (i = 0; i < print_len; i++)
+		bpf_seq_write(seq, &seq_num, sizeof(seq_num));
+
+	return ret;
+}
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_test_kern_common.h b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern_common.h
new file mode 100644
index 000000000000..bdd51cf14b54
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_test_kern_common.h
@@ -0,0 +1,22 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2020 Facebook */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+int count = 0;
+
+SEC("iter/task")
+int dump_task(struct bpf_iter__task *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	char c;
+
+	if (count < 4) {
+		c = START_CHAR + count;
+		bpf_seq_write(seq, &c, sizeof(c));
+		count++;
+	}
+
+	return 0;
+}