Message-ID: <B013A250-9729-465A-BE4C-120AF35B557A@fb.com>
Date:   Tue, 8 May 2018 21:18:51 +0000
From:   Song Liu <songliubraving@...com>
To:     Martin Lau <kafai@...com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH bpf-next 6/6] bpf: btf: Tests for BPF_OBJ_GET_INFO_BY_FD
 and BPF_BTF_GET_FD_BY_ID



> On May 4, 2018, at 2:49 PM, Martin KaFai Lau <kafai@...com> wrote:
> 
> This patch adds test for BPF_BTF_GET_FD_BY_ID and the new
> btf_id/btf_key_id/btf_value_id in the "struct bpf_map_info".
> 
> It also modifies the existing BPF_OBJ_GET_INFO_BY_FD test
> to reflect the new "struct bpf_btf_info".
> 
> Signed-off-by: Martin KaFai Lau <kafai@...com>
> Acked-by: Alexei Starovoitov <ast@...com>
> ---
> tools/lib/bpf/bpf.c                    |  10 ++
> tools/lib/bpf/bpf.h                    |   1 +
> tools/testing/selftests/bpf/test_btf.c | 289 +++++++++++++++++++++++++++++++--
> 3 files changed, 287 insertions(+), 13 deletions(-)
> 
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 76b36cc16e7f..a3a8fb2ac697 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -458,6 +458,16 @@ int bpf_map_get_fd_by_id(__u32 id)
> 	return sys_bpf(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));
> }
> 
> +int bpf_btf_get_fd_by_id(__u32 id)
> +{
> +	union bpf_attr attr;
> +
> +	bzero(&attr, sizeof(attr));
> +	attr.btf_id = id;
> +
> +	return sys_bpf(BPF_BTF_GET_FD_BY_ID, &attr, sizeof(attr));
> +}
> +
> int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len)
> {
> 	union bpf_attr attr;
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index 553b11ad52b3..fb3a146d92ff 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -98,6 +98,7 @@ int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id);
> int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);
> int bpf_prog_get_fd_by_id(__u32 id);
> int bpf_map_get_fd_by_id(__u32 id);
> +int bpf_btf_get_fd_by_id(__u32 id);
> int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len);
> int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
> 		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt);
> diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
> index b7880a20fad1..c8bceae7ec02 100644
> --- a/tools/testing/selftests/bpf/test_btf.c
> +++ b/tools/testing/selftests/bpf/test_btf.c
> @@ -1047,9 +1047,13 @@ struct btf_get_info_test {
> 	const char *str_sec;
> 	__u32 raw_types[MAX_NR_RAW_TYPES];
> 	__u32 str_sec_size;
> -	int info_size_delta;
> +	int btf_size_delta;
> +	int (*special_test)(unsigned int test_num);
> };
> 
> +static int test_big_btf_info(unsigned int test_num);
> +static int test_btf_id(unsigned int test_num);
> +
> const struct btf_get_info_test get_info_tests[] = {
> {
> 	.descr = "== raw_btf_size+1",
> @@ -1060,7 +1064,7 @@ const struct btf_get_info_test get_info_tests[] = {
> 	},
> 	.str_sec = "",
> 	.str_sec_size = sizeof(""),
> -	.info_size_delta = 1,
> +	.btf_size_delta = 1,
> },
> {
> 	.descr = "== raw_btf_size-3",
> @@ -1071,20 +1075,274 @@ const struct btf_get_info_test get_info_tests[] = {
> 	},
> 	.str_sec = "",
> 	.str_sec_size = sizeof(""),
> -	.info_size_delta = -3,
> +	.btf_size_delta = -3,
> +},
> +{
> +	.descr = "Large bpf_btf_info",
> +	.raw_types = {
> +		/* int */				/* [1] */
> +		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
> +		BTF_END_RAW,
> +	},
> +	.str_sec = "",
> +	.str_sec_size = sizeof(""),
> +	.special_test = test_big_btf_info,
> +},
> +{
> +	.descr = "BTF ID",
> +	.raw_types = {
> +		/* int */				/* [1] */
> +		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
> +		/* unsigned int */			/* [2] */
> +		BTF_TYPE_INT_ENC(0, 0, 0, 32, 4),
> +		BTF_END_RAW,
> +	},
> +	.str_sec = "",
> +	.str_sec_size = sizeof(""),
> +	.special_test = test_btf_id,
> },
> };
> 
> +static inline __u64 ptr_to_u64(const void *ptr)
> +{
> +	return (__u64)(unsigned long)ptr;
> +}
> +
> +static int test_big_btf_info(unsigned int test_num)
> +{
> +	const struct btf_get_info_test *test = &get_info_tests[test_num - 1];
> +	uint8_t *raw_btf = NULL, *user_btf = NULL;
> +	unsigned int raw_btf_size;
> +	struct {
> +		struct bpf_btf_info info;
> +		uint64_t garbage;
> +	} info_garbage;
> +	struct bpf_btf_info *info;
> +	int btf_fd = -1, err;
> +	uint32_t info_len;
> +
> +	raw_btf = btf_raw_create(&hdr_tmpl,
> +				 test->raw_types,
> +				 test->str_sec,
> +				 test->str_sec_size,
> +				 &raw_btf_size);
> +
> +	if (!raw_btf)
> +		return -1;
> +
> +	*btf_log_buf = '\0';
> +
> +	user_btf = malloc(raw_btf_size);
> +	if (CHECK(!user_btf, "!user_btf")) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	btf_fd = bpf_load_btf(raw_btf, raw_btf_size,
> +			      btf_log_buf, BTF_LOG_BUF_SIZE,
> +			      args.always_log);
> +	if (CHECK(btf_fd == -1, "errno:%d", errno)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	/*
> +	 * GET_INFO should error out if the userspace info
> +	 * has non zero tailing bytes.
> +	 */
> +	info = &info_garbage.info;
> +	memset(info, 0, sizeof(*info));
> +	info_garbage.garbage = 0xdeadbeef;
> +	info_len = sizeof(info_garbage);
> +	info->btf = ptr_to_u64(user_btf);
> +	info->btf_size = raw_btf_size;
> +
> +	err = bpf_obj_get_info_by_fd(btf_fd, info, &info_len);
> +	if (CHECK(!err, "!err")) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	/*
> +	 * GET_INFO should succeed even info_len is larger than
> +	 * the kernel supported as long as tailing bytes are zero.
> +	 * The kernel supported info len should also be returned
> +	 * to userspace.
> +	 */
> +	info_garbage.garbage = 0;
> +	err = bpf_obj_get_info_by_fd(btf_fd, info, &info_len);
> +	if (CHECK(err || info_len != sizeof(*info),
> +		  "err:%d errno:%d info_len:%u sizeof(*info):%lu",
> +		  err, errno, info_len, sizeof(*info))) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	fprintf(stderr, "OK");
> +
> +done:
> +	if (*btf_log_buf && (err || args.always_log))
> +		fprintf(stderr, "\n%s", btf_log_buf);
> +
> +	free(raw_btf);
> +	free(user_btf);
> +
> +	if (btf_fd != -1)
> +		close(btf_fd);
> +
> +	return err;
> +}
> +
> +static int test_btf_id(unsigned int test_num)
> +{
> +	const struct btf_get_info_test *test = &get_info_tests[test_num - 1];
> +	struct bpf_create_map_attr create_attr = {};
> +	uint8_t *raw_btf = NULL, *user_btf[2] = {};
> +	int btf_fd[2] = {-1, -1}, map_fd = -1;
> +	struct bpf_map_info map_info = {};
> +	struct bpf_btf_info info[2] = {};
> +	unsigned int raw_btf_size;
> +	uint32_t info_len;
> +	int err, i, ret;
> +
> +	raw_btf = btf_raw_create(&hdr_tmpl,
> +				 test->raw_types,
> +				 test->str_sec,
> +				 test->str_sec_size,
> +				 &raw_btf_size);
> +
> +	if (!raw_btf)
> +		return -1;
> +
> +	*btf_log_buf = '\0';
> +
> +	for (i = 0; i < 2; i++) {
> +		user_btf[i] = malloc(raw_btf_size);
> +		if (CHECK(!user_btf[i], "!user_btf[%d]", i)) {
> +			err = -1;
> +			goto done;
> +		}
> +		info[i].btf = ptr_to_u64(user_btf[i]);
> +		info[i].btf_size = raw_btf_size;
> +	}
> +
> +	btf_fd[0] = bpf_load_btf(raw_btf, raw_btf_size,
> +				 btf_log_buf, BTF_LOG_BUF_SIZE,
> +				 args.always_log);
> +	if (CHECK(btf_fd[0] == -1, "errno:%d", errno)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	/* Test BPF_OBJ_GET_INFO_BY_ID on btf_id */
> +	info_len = sizeof(info[0]);
> +	err = bpf_obj_get_info_by_fd(btf_fd[0], &info[0], &info_len);
> +	if (CHECK(err, "errno:%d", errno)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	btf_fd[1] = bpf_btf_get_fd_by_id(info[0].id);
> +	if (CHECK(btf_fd[1] == -1, "errno:%d", errno)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	ret = 0;
> +	err = bpf_obj_get_info_by_fd(btf_fd[1], &info[1], &info_len);
> +	if (CHECK(err || info[0].id != info[1].id ||
> +		  info[0].btf_size != info[1].btf_size ||
> +		  (ret = memcmp(user_btf[0], user_btf[1], info[0].btf_size)),
> +		  "err:%d errno:%d id0:%u id1:%u btf_size0:%u btf_size1:%u memcmp:%d",
> +		  err, errno, info[0].id, info[1].id,
> +		  info[0].btf_size, info[1].btf_size, ret)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	/* Test btf members in struct bpf_map_info */
> +	create_attr.name = "test_btf_id";
> +	create_attr.map_type = BPF_MAP_TYPE_ARRAY;
> +	create_attr.key_size = sizeof(int);
> +	create_attr.value_size = sizeof(unsigned int);
> +	create_attr.max_entries = 4;
> +	create_attr.btf_fd = btf_fd[0];
> +	create_attr.btf_key_id = 1;
> +	create_attr.btf_value_id = 2;
> +
> +	map_fd = bpf_create_map_xattr(&create_attr);
> +	if (CHECK(map_fd == -1, "errno:%d", errno)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	info_len = sizeof(map_info);
> +	err = bpf_obj_get_info_by_fd(map_fd, &map_info, &info_len);
> +	if (CHECK(err || map_info.btf_id != info[0].id ||
> +		  map_info.btf_key_id != 1 || map_info.btf_value_id != 2,
> +		  "err:%d errno:%d info.id:%u btf_id:%u btf_key_id:%u btf_value_id:%u",
> +		  err, errno, info[0].id, map_info.btf_id, map_info.btf_key_id,
> +		  map_info.btf_value_id)) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	for (i = 0; i < 2; i++) {
> +		close(btf_fd[i]);
> +		btf_fd[i] = -1;
> +	}
> +
> +	/* Test BTF ID is removed from the kernel */
> +	btf_fd[0] = bpf_btf_get_fd_by_id(map_info.btf_id);
> +	if (CHECK(btf_fd[0] == -1, "errno:%d", errno)) {
> +		err = -1;
> +		goto done;
> +	}
> +	close(btf_fd[0]);
> +	btf_fd[0] = -1;
> +
> +	/* The map holds the last ref to BTF and its btf_id */
> +	close(map_fd);
> +	map_fd = -1;
> +	btf_fd[0] = bpf_btf_get_fd_by_id(map_info.btf_id);
> +	if (CHECK(btf_fd[0] != -1, "BTF lingers")) {
> +		err = -1;
> +		goto done;
> +	}
> +
> +	fprintf(stderr, "OK");
> +
> +done:
> +	if (*btf_log_buf && (err || args.always_log))
> +		fprintf(stderr, "\n%s", btf_log_buf);
> +
> +	free(raw_btf);
> +	if (map_fd != -1)
> +		close(map_fd);
> +	for (i = 0; i < 2; i++) {
> +		free(user_btf[i]);
> +		if (btf_fd[i] != -1)
> +			close(btf_fd[i]);
> +	}
> +
> +	return err;
> +}
> +
> static int do_test_get_info(unsigned int test_num)
> {
> 	const struct btf_get_info_test *test = &get_info_tests[test_num - 1];
> 	unsigned int raw_btf_size, user_btf_size, expected_nbytes;
> 	uint8_t *raw_btf = NULL, *user_btf = NULL;
> -	int btf_fd = -1, err;
> +	struct bpf_btf_info info = {};
> +	int btf_fd = -1, err, ret;
> +	uint32_t info_len;
> 
> -	fprintf(stderr, "BTF GET_INFO_BY_ID test[%u] (%s): ",
> +	fprintf(stderr, "BTF GET_INFO test[%u] (%s): ",
> 		test_num, test->descr);
> 
> +	if (test->special_test)
> +		return test->special_test(test_num);
> +
> 	raw_btf = btf_raw_create(&hdr_tmpl,
> 				 test->raw_types,
> 				 test->str_sec,
> @@ -1110,19 +1368,24 @@ static int do_test_get_info(unsigned int test_num)
> 		goto done;
> 	}
> 
> -	user_btf_size = (int)raw_btf_size + test->info_size_delta;
> +	user_btf_size = (int)raw_btf_size + test->btf_size_delta;
> 	expected_nbytes = min(raw_btf_size, user_btf_size);
> 	if (raw_btf_size > expected_nbytes)
> 		memset(user_btf + expected_nbytes, 0xff,
> 		       raw_btf_size - expected_nbytes);
> 
> -	err = bpf_obj_get_info_by_fd(btf_fd, user_btf, &user_btf_size);
> -	if (CHECK(err || user_btf_size != raw_btf_size ||
> -		  memcmp(raw_btf, user_btf, expected_nbytes),
> -		  "err:%d(errno:%d) raw_btf_size:%u user_btf_size:%u expected_nbytes:%u memcmp:%d",
> -		  err, errno,
> -		  raw_btf_size, user_btf_size, expected_nbytes,
> -		  memcmp(raw_btf, user_btf, expected_nbytes))) {
> +	info_len = sizeof(info);
> +	info.btf = ptr_to_u64(user_btf);
> +	info.btf_size = user_btf_size;
> +
> +	ret = 0;
> +	err = bpf_obj_get_info_by_fd(btf_fd, &info, &info_len);
> +	if (CHECK(err || !info.id || info_len != sizeof(info) ||
> +		  info.btf_size != raw_btf_size ||
> +		  (ret = memcmp(raw_btf, user_btf, expected_nbytes)),
> +		  "err:%d errno:%d info.id:%u info_len:%u sizeof(info):%lu raw_btf_size:%u info.btf_size:%u expected_nbytes:%u memcmp:%d",
> +		  err, errno, info.id, info_len, sizeof(info),
> +		  raw_btf_size, info.btf_size, expected_nbytes, ret)) {
> 		err = -1;
> 		goto done;
> 	}
> -- 
> 2.9.5
> 

Acked-by: Song Liu <songliubraving@...com>

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