diff mbox series

[v5,bpf-next,3/3] selftests/bpf: add dump type data tests to btf dump tests

Message ID 1624092968-5598-4-git-send-email-alan.maguire@oracle.com
State New
Headers show
Series None | expand

Commit Message

Alan Maguire June 19, 2021, 8:56 a.m. UTC
Test various type data dumping operations by comparing expected
format with the dumped string; an snprintf-style printf function
is used to record the string dumped.  Also verify overflow handling
where the data passed does not cover the full size of a type,
such as would occur if a tracer has a portion of the 8k
"struct task_struct".

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 tools/testing/selftests/bpf/prog_tests/btf_dump.c | 644 ++++++++++++++++++++++
 1 file changed, 644 insertions(+)

Comments

Andrii Nakryiko July 7, 2021, 3:51 a.m. UTC | #1
On Sat, Jun 19, 2021 at 1:56 AM Alan Maguire <alan.maguire@oracle.com> wrote:
>

> Test various type data dumping operations by comparing expected

> format with the dumped string; an snprintf-style printf function

> is used to record the string dumped.  Also verify overflow handling

> where the data passed does not cover the full size of a type,

> such as would occur if a tracer has a portion of the 8k

> "struct task_struct".

>

> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>

> ---

>  tools/testing/selftests/bpf/prog_tests/btf_dump.c | 644 ++++++++++++++++++++++

>  1 file changed, 644 insertions(+)

>

> diff --git a/tools/testing/selftests/bpf/prog_tests/btf_dump.c b/tools/testing/selftests/bpf/prog_tests/btf_dump.c

> index 1b90e68..c894201 100644

> --- a/tools/testing/selftests/bpf/prog_tests/btf_dump.c

> +++ b/tools/testing/selftests/bpf/prog_tests/btf_dump.c

> @@ -232,7 +232,621 @@ void test_btf_dump_incremental(void)

>         btf__free(btf);

>  }

>

> +#define STRSIZE                                4096

> +

> +static void btf_dump_snprintf(void *ctx, const char *fmt, va_list args)

> +{

> +       char *s = ctx, new[STRSIZE];

> +

> +       vsnprintf(new, STRSIZE, fmt, args);

> +       strncat(s, new, STRSIZE);


this can cause stack corruption, because strncat doesn't take into
account the length of string in s and might copy all STRSIZE bytes
from new. What you want here is actually strlcat() variant, but I'm
not sure it's available in Linux glibc. Instead, you have to pass
STRSIZE - strlen(s) - 1 to strncat.

> +}

> +

> +/* skip "enum "/"struct " prefixes */

> +#define SKIP_PREFIX(_typestr, _prefix)                                 \

> +       do {                                                            \

> +               if (strncmp(_typestr, _prefix, strlen(_prefix)) == 0)   \

> +                       _typestr += strlen(_prefix) + 1;                \


If you expect "enum " or "struct " (not, say, "enum/"), then the test
should just pass that in explicitly instead of SKIP_PREFIX silently
ignoring an extra *any* character.


> +       } while (0)

> +


[...]

> +/* overflow test; pass typesize < expected type size, ensure E2BIG returned */

> +#define TEST_BTF_DUMP_DATA_OVER(_b, _d, _str, _type, _type_sz, _expected, ...)\

> +       do {                                                            \

> +               char __ptrtype[64] = #_type;                            \

> +               char *_ptrtype = (char *)__ptrtype;                     \

> +               _type _ptrdata = __VA_ARGS__;                           \

> +               void *_ptr = &_ptrdata;                                 \

> +               int _err;                                               \

> +                                                                       \

> +               _err = btf_dump_data(_b, _d, _ptrtype, 0, _ptr,         \

> +                                    _type_sz, _str, _expected);        \

> +               if (_err < 0)                                           \

> +                       return;                                         \


don't return, let all the validation run. It's better to see all the
failures than fix one by one, recompile, rerun, then fix another one.
Same for TEST_BTF_DUMP_DATA above.

> +       } while (0)

> +

> +#define TEST_BTF_DUMP_VAR(_b, _d, _str, _var, _type, _flags, _expected, ...) \

> +       do {                                                            \

> +               _type _ptrdata = __VA_ARGS__;                           \

> +               void *_ptr = &_ptrdata;                                 \

> +               int _err;                                               \

> +                                                                       \

> +               _err = btf_dump_data(_b, _d, _var, _flags, _ptr,        \

> +                                    sizeof(_type), _str, _expected);   \

> +               if (_err < 0)                                           \

> +                       return;                                         \


same, don't return early

> +       } while (0)

> +

> +static void test_btf_dump_int_data(struct btf *btf, struct btf_dump *d,

> +                                  char *str)

> +{

> +       /* simple int */

> +       TEST_BTF_DUMP_DATA_C(btf, d, str, int, BTF_F_COMPACT, 1234);

> +       TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_NONAME,

> +                          "1234", 1234);

> +       TEST_BTF_DUMP_DATA(btf, d, str, int, 0, "(int)1234", 1234);

> +

> +       /* zero value should be printed at toplevel */

> +       TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT, "(int)0", 0);

> +       TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_NONAME,

> +                          "0", 0);

> +       TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_ZERO,

> +                          "(int)0", 0);

> +       TEST_BTF_DUMP_DATA(btf, d, str, int,

> +                          BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,

> +                          "0", 0);

> +       TEST_BTF_DUMP_DATA_C(btf, d, str, int, BTF_F_COMPACT, -4567);

> +       TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_NONAME,

> +                          "-4567", -4567);

> +       TEST_BTF_DUMP_DATA(btf, d, str, int, 0, "(int)-4567", -4567);

> +

> +       TEST_BTF_DUMP_DATA_OVER(btf, d, str, int, sizeof(int)-1, "", 1);


all of these validations are independent of each other, so there is no
need to return early if any one fails (see above)

> +}

> +

> +static void test_btf_dump_float_data(struct btf *btf, struct btf_dump *d,

> +                                    char *str)

> +{

> +       float t1 = 1.234567;

> +       float t2 = -1.234567;

> +       float t3 = 0.0;

> +       double t4 = 5.678912;

> +       double t5 = -5.678912;

> +       double t6 = 0.0;

> +       long double t7 = 9.876543;

> +       long double t8 = -9.876543;

> +       long double t9 = 0.0;

> +

> +       /* since the kernel does not likely have any float types in its BTF, we

> +        * will need to add some of various sizes.

> +        */

> +

> +       if (!ASSERT_GT(btf__add_float(btf, "test_float", 4), 0, "add float"))

> +               return;

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_float", 0, &t1, 4, str,

> +                                    "(test_float)1.234567"), "dump float"))

> +               return;

> +

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_float", 0, &t2, 4, str,

> +                                    "(test_float)-1.234567"), "dump float"))

> +               return;

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_float", 0, &t3, 4, str,

> +                                    "(test_float)0.000000"), "dump float"))

> +               return;

> +

> +       if (!ASSERT_GT(btf__add_float(btf, "test_double", 8), 0, "add_double"))

> +               return;

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_double", 0, &t4, 8, str,

> +                                    "(test_double)5.678912"), "dump double"))

> +               return;

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_double", 0, &t5, 8, str,

> +                                    "(test_double)-5.678912"), "dump double"))

> +               return;

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_double", 0, &t6, 8, str,

> +                                    "(test_double)0.000000"), "dump double"))

> +               return;

> +

> +       if (!ASSERT_GT(btf__add_float(btf, "test_long_double", 16), 0,

> +                      "add_long_double"))

> +               return;

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_long_double", 0, &t7, 16,

> +                                    str, "(test_long_double)9.876543"),

> +                                    "dump long_double"))

> +               return;

> +       if (!ASSERT_OK(btf_dump_data(btf, d, "test_long_double", 0, &t8, 16,

> +                                    str, "(test_long_double)-9.876543"),

> +                                    "dump long_double"))

> +               return;

> +       ASSERT_OK(btf_dump_data(btf, d, "test_long_double", 0, &t9, 16,

> +                               str, "(test_long_double)0.000000"),

> +                               "dump long_double");


same, don't return, just have a list of assertions

> +}

> +


[...]

> +                          { .next = (struct list_head *)1 });

> +       /* NULL pointer should not be displayed */

> +       TEST_BTF_DUMP_DATA(btf, d, str, struct list_head, BTF_F_COMPACT,

> +                          "(struct list_head){}",

> +                          { .next = (struct list_head *)0 });

> +       TEST_BTF_DUMP_DATA(btf, d, str, struct list_head, 0,

> +"(struct list_head){\n"

> +"}",

> +                          { .next = (struct list_head *)0 });

> +

> +       /* struct with function pointers */

> +       type_id = btf__find_by_name(btf, "file_operations");

> +       if (CHECK(type_id <= 0, "find type id",


some more CHECK leftovers, please switch all CHECKs to ASSERT_xxx

> +                 "no 'struct file_operations' in BTF: %d\n", type_id))

> +               return;

> +       type_sz = btf__resolve_size(btf, type_id);

> +       str[0] = '\0';

> +

> +       ret = btf_dump__dump_type_data(d, type_id, fops, type_sz, &opts);

> +       if (CHECK(ret != type_sz,

> +                 "dump file_operations is successful",

> +                 "unexpected return value dumping file_operations '%s': %d\n",

> +                 str, ret))

> +               return;

> +

> +       cmpstr =

> +"(struct file_operations){\n"

> +"      .owner = (struct module *)0xffffffffffffffff,\n"

> +"      .llseek = (loff_t (*)(struct file *, loff_t, int))0xffffffffffffffff,";

> +

> +       if (!ASSERT_STRNEQ(str, cmpstr, strlen(cmpstr), "file_operations"))

> +               return;


same as above, even if this fails, we can still run all the other
validations safely

> +

> +       /* struct with char array */

> +       TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_prog_info, BTF_F_COMPACT,

> +                          "(struct bpf_prog_info){.name = (char[16])['f','o','o',],}",

> +                          { .name = "foo",});

> +       TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_prog_info,

> +                          BTF_F_COMPACT | BTF_F_NONAME,

> +                          "{['f','o','o',],}",

> +                          {.name = "foo",});


[...]

>  void test_btf_dump() {

> +       char str[STRSIZE];

> +       struct btf_dump_opts opts = { .ctx = str };

> +       struct btf_dump *d;

> +       struct btf *btf;

>         int i;

>

>         for (i = 0; i < ARRAY_SIZE(btf_dump_test_cases); i++) {

> @@ -245,4 +859,34 @@ void test_btf_dump() {

>         }

>         if (test__start_subtest("btf_dump: incremental"))

>                 test_btf_dump_incremental();

> +

> +       btf = libbpf_find_kernel_btf();

> +       if (CHECK(!btf, "get kernel BTF", "no kernel BTF found"))

> +               return;

> +

> +       d = btf_dump__new(btf, NULL, &opts, btf_dump_snprintf);

> +

> +       if (CHECK(!d, "new dump", "could not create BTF dump"))

> +               return;


goto clean and free dumper and btf?

> +

> +       /* Verify type display for various types. */

> +       if (test__start_subtest("btf_dump: int_data"))

> +               test_btf_dump_int_data(btf, d, str);

> +       if (test__start_subtest("btf_dump: float_data"))

> +               test_btf_dump_float_data(btf, d, str);

> +       if (test__start_subtest("btf_dump: char_data"))

> +               test_btf_dump_char_data(btf, d, str);

> +       if (test__start_subtest("btf_dump: typedef_data"))

> +               test_btf_dump_typedef_data(btf, d, str);

> +       if (test__start_subtest("btf_dump: enum_data"))

> +               test_btf_dump_enum_data(btf, d, str);

> +       if (test__start_subtest("btf_dump: struct_data"))

> +               test_btf_dump_struct_data(btf, d, str);

> +       if (test__start_subtest("btf_dump: var_data"))

> +               test_btf_dump_var_data(btf, d, str);

> +       btf_dump__free(d);

> +       btf__free(btf);

> +

> +       if (test__start_subtest("btf_dump: datasec_data"))

> +               test_btf_dump_datasec_data(str);

>  }

> --

> 1.8.3.1

>
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/btf_dump.c b/tools/testing/selftests/bpf/prog_tests/btf_dump.c
index 1b90e68..c894201 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf_dump.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_dump.c
@@ -232,7 +232,621 @@  void test_btf_dump_incremental(void)
 	btf__free(btf);
 }
 
+#define STRSIZE				4096
+
+static void btf_dump_snprintf(void *ctx, const char *fmt, va_list args)
+{
+	char *s = ctx, new[STRSIZE];
+
+	vsnprintf(new, STRSIZE, fmt, args);
+	strncat(s, new, STRSIZE);
+}
+
+/* skip "enum "/"struct " prefixes */
+#define SKIP_PREFIX(_typestr, _prefix)					\
+	do {								\
+		if (strncmp(_typestr, _prefix, strlen(_prefix)) == 0)	\
+			_typestr += strlen(_prefix) + 1;		\
+	} while (0)
+
+static int btf_dump_data(struct btf *btf, struct btf_dump *d,
+			 char *name, __u64 flags, void *ptr,
+			 size_t ptr_sz, char *str, const char *expected_val)
+{
+	DECLARE_LIBBPF_OPTS(btf_dump_type_data_opts, opts);
+	size_t type_sz;
+	__s32 type_id;
+	int ret = 0;
+
+	if (flags & BTF_F_COMPACT)
+		opts.compact = true;
+	if (flags & BTF_F_NONAME)
+		opts.skip_names = true;
+	if (flags & BTF_F_ZERO)
+		opts.emit_zeroes = true;
+	SKIP_PREFIX(name, "enum");
+	SKIP_PREFIX(name, "struct");
+	SKIP_PREFIX(name, "union");
+	type_id = btf__find_by_name(btf, name);
+	if (!ASSERT_GE(type_id, 0, "find type id"))
+		return -ENOENT;
+	type_sz = btf__resolve_size(btf, type_id);
+	str[0] = '\0';
+	ret = btf_dump__dump_type_data(d, type_id, ptr, ptr_sz, &opts);
+	if (type_sz <= ptr_sz) {
+		if (!ASSERT_EQ(ret, type_sz, "failed/unexpected type_sz"))
+			return -EINVAL;
+	} else {
+		if (!ASSERT_EQ(ret, -E2BIG, "failed to return -E2BIG"))
+			return -EINVAL;
+	}
+	if (!ASSERT_STREQ(str, expected_val, "ensure expected/actual match"))
+		return -EFAULT;
+	return 0;
+}
+
+#define TEST_BTF_DUMP_DATA(_b, _d, _str, _type, _flags, _expected, ...)	\
+	do {								\
+		char __ptrtype[64] = #_type;				\
+		char *_ptrtype = (char *)__ptrtype;			\
+		_type _ptrdata = __VA_ARGS__;				\
+		void *_ptr = &_ptrdata;					\
+		int _err;						\
+									\
+		_err = btf_dump_data(_b, _d, _ptrtype, _flags, _ptr,	\
+				     sizeof(_type), _str, _expected);	\
+		if (_err < 0)						\
+			return;						\
+	} while (0)
+
+/* Use where expected data string matches its stringified declaration */
+#define TEST_BTF_DUMP_DATA_C(_b, _d, _str, _type, _flags, ...)		\
+	TEST_BTF_DUMP_DATA(_b, _d, _str, _type, _flags,			\
+			   "(" #_type ")" #__VA_ARGS__,	__VA_ARGS__)
+
+/* overflow test; pass typesize < expected type size, ensure E2BIG returned */
+#define TEST_BTF_DUMP_DATA_OVER(_b, _d, _str, _type, _type_sz, _expected, ...)\
+	do {								\
+		char __ptrtype[64] = #_type;				\
+		char *_ptrtype = (char *)__ptrtype;			\
+		_type _ptrdata = __VA_ARGS__;				\
+		void *_ptr = &_ptrdata;					\
+		int _err;						\
+									\
+		_err = btf_dump_data(_b, _d, _ptrtype, 0, _ptr,		\
+				     _type_sz, _str, _expected);	\
+		if (_err < 0)						\
+			return;						\
+	} while (0)
+
+#define TEST_BTF_DUMP_VAR(_b, _d, _str, _var, _type, _flags, _expected, ...) \
+	do {								\
+		_type _ptrdata = __VA_ARGS__;				\
+		void *_ptr = &_ptrdata;					\
+		int _err;						\
+									\
+		_err = btf_dump_data(_b, _d, _var, _flags, _ptr,	\
+				     sizeof(_type), _str, _expected);	\
+		if (_err < 0)						\
+			return;						\
+	} while (0)
+
+static void test_btf_dump_int_data(struct btf *btf, struct btf_dump *d,
+				   char *str)
+{
+	/* simple int */
+	TEST_BTF_DUMP_DATA_C(btf, d, str, int, BTF_F_COMPACT, 1234);
+	TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_NONAME,
+			   "1234", 1234);
+	TEST_BTF_DUMP_DATA(btf, d, str, int, 0, "(int)1234", 1234);
+
+	/* zero value should be printed at toplevel */
+	TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT, "(int)0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_NONAME,
+			   "0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_ZERO,
+			   "(int)0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, int,
+			   BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,
+			   "0", 0);
+	TEST_BTF_DUMP_DATA_C(btf, d, str, int, BTF_F_COMPACT, -4567);
+	TEST_BTF_DUMP_DATA(btf, d, str, int, BTF_F_COMPACT | BTF_F_NONAME,
+			   "-4567", -4567);
+	TEST_BTF_DUMP_DATA(btf, d, str, int, 0, "(int)-4567", -4567);
+
+	TEST_BTF_DUMP_DATA_OVER(btf, d, str, int, sizeof(int)-1, "", 1);
+}
+
+static void test_btf_dump_float_data(struct btf *btf, struct btf_dump *d,
+				     char *str)
+{
+	float t1 = 1.234567;
+	float t2 = -1.234567;
+	float t3 = 0.0;
+	double t4 = 5.678912;
+	double t5 = -5.678912;
+	double t6 = 0.0;
+	long double t7 = 9.876543;
+	long double t8 = -9.876543;
+	long double t9 = 0.0;
+
+	/* since the kernel does not likely have any float types in its BTF, we
+	 * will need to add some of various sizes.
+	 */
+
+	if (!ASSERT_GT(btf__add_float(btf, "test_float", 4), 0, "add float"))
+		return;
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_float", 0, &t1, 4, str,
+				     "(test_float)1.234567"), "dump float"))
+		return;
+
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_float", 0, &t2, 4, str,
+				     "(test_float)-1.234567"), "dump float"))
+		return;
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_float", 0, &t3, 4, str,
+				     "(test_float)0.000000"), "dump float"))
+		return;
+
+	if (!ASSERT_GT(btf__add_float(btf, "test_double", 8), 0, "add_double"))
+		return;
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_double", 0, &t4, 8, str,
+				     "(test_double)5.678912"), "dump double"))
+		return;
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_double", 0, &t5, 8, str,
+				     "(test_double)-5.678912"), "dump double"))
+		return;
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_double", 0, &t6, 8, str,
+				     "(test_double)0.000000"), "dump double"))
+		return;
+
+	if (!ASSERT_GT(btf__add_float(btf, "test_long_double", 16), 0,
+		       "add_long_double"))
+		return;
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_long_double", 0, &t7, 16,
+				     str, "(test_long_double)9.876543"),
+				     "dump long_double"))
+		return;
+	if (!ASSERT_OK(btf_dump_data(btf, d, "test_long_double", 0, &t8, 16,
+				     str, "(test_long_double)-9.876543"),
+				     "dump long_double"))
+		return;
+	ASSERT_OK(btf_dump_data(btf, d, "test_long_double", 0, &t9, 16,
+				str, "(test_long_double)0.000000"),
+				"dump long_double");
+}
+
+static void test_btf_dump_char_data(struct btf *btf, struct btf_dump *d,
+				    char *str)
+{
+	/* simple char */
+	TEST_BTF_DUMP_DATA_C(btf, d, str, char, BTF_F_COMPACT, 100);
+	TEST_BTF_DUMP_DATA(btf, d, str, char, BTF_F_COMPACT | BTF_F_NONAME,
+			   "100", 100);
+	TEST_BTF_DUMP_DATA(btf, d, str, char, 0, "(char)100", 100);
+	/* zero value should be printed at toplevel */
+	TEST_BTF_DUMP_DATA(btf, d, str, char, BTF_F_COMPACT, "(char)0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, char, BTF_F_COMPACT | BTF_F_NONAME,
+			   "0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, char, BTF_F_COMPACT | BTF_F_ZERO,
+			   "(char)0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, char,
+			   BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,
+			   "0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, char, 0, "(char)0", 0);
+
+	TEST_BTF_DUMP_DATA_OVER(btf, d, str, char, sizeof(char)-1, "", 100);
+}
+
+static void test_btf_dump_typedef_data(struct btf *btf, struct btf_dump *d,
+				       char *str)
+{
+	/* simple typedef */
+	TEST_BTF_DUMP_DATA_C(btf, d, str, uint64_t, BTF_F_COMPACT, 100);
+	TEST_BTF_DUMP_DATA(btf, d, str, u64, BTF_F_COMPACT | BTF_F_NONAME,
+			   "1", 1);
+	TEST_BTF_DUMP_DATA(btf, d, str, u64, 0, "(u64)1", 1);
+	/* zero value should be printed at toplevel */
+	TEST_BTF_DUMP_DATA(btf, d, str, u64, BTF_F_COMPACT, "(u64)0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, u64, BTF_F_COMPACT | BTF_F_NONAME,
+			   "0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, u64, BTF_F_COMPACT | BTF_F_ZERO,
+			   "(u64)0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, u64,
+			   BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,
+			   "0", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, u64, 0, "(u64)0", 0);
+
+	/* typedef struct */
+	TEST_BTF_DUMP_DATA_C(btf, d, str, atomic_t, BTF_F_COMPACT,
+			     {.counter = (int)1,});
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t, BTF_F_COMPACT | BTF_F_NONAME,
+			   "{1,}", { .counter = 1 });
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t, 0,
+"(atomic_t){\n"
+"	.counter = (int)1,\n"
+"}",
+			   {.counter = 1,});
+	/* typedef with 0 value should be printed at toplevel */
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t, BTF_F_COMPACT, "(atomic_t){}",
+			   {.counter = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t, BTF_F_COMPACT | BTF_F_NONAME,
+			   "{}", {.counter = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t, 0,
+"(atomic_t){\n"
+"}",
+			   {.counter = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t, BTF_F_COMPACT | BTF_F_ZERO,
+			   "(atomic_t){.counter = (int)0,}",
+			   {.counter = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t,
+			   BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,
+			   "{0,}", {.counter = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, atomic_t, BTF_F_ZERO,
+"(atomic_t){\n"
+"	.counter = (int)0,\n"
+"}",
+			   { .counter = 0,});
+
+	/* overflow should show type but not value since it overflows */
+	TEST_BTF_DUMP_DATA_OVER(btf, d, str, atomic_t, sizeof(atomic_t)-1,
+				"(atomic_t){\n", { .counter = 1});
+}
+
+static void test_btf_dump_enum_data(struct btf *btf, struct btf_dump *d,
+				    char *str)
+{
+	/* enum where enum value does (and does not) exist */
+	TEST_BTF_DUMP_DATA_C(btf, d, str, enum bpf_cmd, BTF_F_COMPACT,
+			     BPF_MAP_CREATE);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd, BTF_F_COMPACT,
+			   "(enum bpf_cmd)BPF_MAP_CREATE", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "BPF_MAP_CREATE",
+			   BPF_MAP_CREATE);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd, 0,
+			   "(enum bpf_cmd)BPF_MAP_CREATE",
+			   BPF_MAP_CREATE);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd,
+			   BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,
+			   "BPF_MAP_CREATE", 0);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd,
+			   BTF_F_COMPACT | BTF_F_ZERO,
+			   "(enum bpf_cmd)BPF_MAP_CREATE",
+			   BPF_MAP_CREATE);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd,
+			   BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,
+			   "BPF_MAP_CREATE", BPF_MAP_CREATE);
+	TEST_BTF_DUMP_DATA_C(btf, d, str, enum bpf_cmd, BTF_F_COMPACT, 2000);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "2000", 2000);
+	TEST_BTF_DUMP_DATA(btf, d, str, enum bpf_cmd, 0,
+			   "(enum bpf_cmd)2000", 2000);
+
+	TEST_BTF_DUMP_DATA_OVER(btf, d, str, enum bpf_cmd,
+				sizeof(enum bpf_cmd) - 1, "", BPF_MAP_CREATE);
+}
+
+static void test_btf_dump_struct_data(struct btf *btf, struct btf_dump *d,
+				      char *str)
+{
+	DECLARE_LIBBPF_OPTS(btf_dump_type_data_opts, opts);
+	char zero_data[512] = { };
+	char type_data[512];
+	void *fops = type_data;
+	void *skb = type_data;
+	size_t type_sz;
+	__s32 type_id;
+	char *cmpstr;
+	int ret;
+
+	memset(type_data, 255, sizeof(type_data));
+
+	/* simple struct */
+	TEST_BTF_DUMP_DATA_C(btf, d, str, struct btf_enum, BTF_F_COMPACT,
+			     {.name_off = (__u32)3,.val = (__s32)-1,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "{3,-1,}",
+			   { .name_off = 3, .val = -1,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum, 0,
+"(struct btf_enum){\n"
+"	.name_off = (__u32)3,\n"
+"	.val = (__s32)-1,\n"
+"}",
+			   { .name_off = 3, .val = -1,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "{-1,}",
+			   { .name_off = 0, .val = -1,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum,
+			   BTF_F_COMPACT | BTF_F_NONAME | BTF_F_ZERO,
+			   "{0,-1,}",
+			   { .name_off = 0, .val = -1,});
+	/* empty struct should be printed */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum, BTF_F_COMPACT,
+			   "(struct btf_enum){}",
+			   { .name_off = 0, .val = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "{}",
+			   { .name_off = 0, .val = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum, 0,
+"(struct btf_enum){\n"
+"}",
+			   { .name_off = 0, .val = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum,
+			   BTF_F_COMPACT | BTF_F_ZERO,
+			   "(struct btf_enum){.name_off = (__u32)0,.val = (__s32)0,}",
+			   { .name_off = 0, .val = 0,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct btf_enum,
+			   BTF_F_ZERO,
+"(struct btf_enum){\n"
+"	.name_off = (__u32)0,\n"
+"	.val = (__s32)0,\n"
+"}",
+			   { .name_off = 0, .val = 0,});
+
+	/* struct with pointers */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct list_head, BTF_F_COMPACT,
+			   "(struct list_head){.next = (struct list_head *)0x1,}",
+			   { .next = (struct list_head *)1 });
+	TEST_BTF_DUMP_DATA(btf, d, str, struct list_head, 0,
+"(struct list_head){\n"
+"	.next = (struct list_head *)0x1,\n"
+"}",
+			   { .next = (struct list_head *)1 });
+	/* NULL pointer should not be displayed */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct list_head, BTF_F_COMPACT,
+			   "(struct list_head){}",
+			   { .next = (struct list_head *)0 });
+	TEST_BTF_DUMP_DATA(btf, d, str, struct list_head, 0,
+"(struct list_head){\n"
+"}",
+			   { .next = (struct list_head *)0 });
+
+	/* struct with function pointers */
+	type_id = btf__find_by_name(btf, "file_operations");
+	if (CHECK(type_id <= 0, "find type id",
+		  "no 'struct file_operations' in BTF: %d\n", type_id))
+		return;
+	type_sz = btf__resolve_size(btf, type_id);
+	str[0] = '\0';
+
+	ret = btf_dump__dump_type_data(d, type_id, fops, type_sz, &opts);
+	if (CHECK(ret != type_sz,
+		  "dump file_operations is successful",
+		  "unexpected return value dumping file_operations '%s': %d\n",
+		  str, ret))
+		return;
+
+	cmpstr =
+"(struct file_operations){\n"
+"	.owner = (struct module *)0xffffffffffffffff,\n"
+"	.llseek = (loff_t (*)(struct file *, loff_t, int))0xffffffffffffffff,";
+
+	if (!ASSERT_STRNEQ(str, cmpstr, strlen(cmpstr), "file_operations"))
+		return;
+
+	/* struct with char array */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_prog_info, BTF_F_COMPACT,
+			   "(struct bpf_prog_info){.name = (char[16])['f','o','o',],}",
+			   { .name = "foo",});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_prog_info,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "{['f','o','o',],}",
+			   {.name = "foo",});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_prog_info, 0,
+"(struct bpf_prog_info){\n"
+"	.name = (char[16])[\n"
+"		'f',\n"
+"		'o',\n"
+"		'o',\n"
+"	],\n"
+"}",
+			   {.name = "foo",});
+	/* leading null char means do not display string */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_prog_info, BTF_F_COMPACT,
+			   "(struct bpf_prog_info){}",
+			   {.name = {'\0', 'f', 'o', 'o'}});
+	/* handle non-printable characters */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_prog_info, BTF_F_COMPACT,
+			   "(struct bpf_prog_info){.name = (char[16])[1,2,3,],}",
+			   { .name = {1, 2, 3, 0}});
+
+	/* struct with non-char array */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct __sk_buff, BTF_F_COMPACT,
+			   "(struct __sk_buff){.cb = (__u32[5])[1,2,3,4,5,],}",
+			   { .cb = {1, 2, 3, 4, 5,},});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct __sk_buff,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "{[1,2,3,4,5,],}",
+			   { .cb = { 1, 2, 3, 4, 5},});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct __sk_buff, 0,
+"(struct __sk_buff){\n"
+"	.cb = (__u32[5])[\n"
+"		1,\n"
+"		2,\n"
+"		3,\n"
+"		4,\n"
+"		5,\n"
+"	],\n"
+"}",
+			   { .cb = { 1, 2, 3, 4, 5},});
+	/* For non-char, arrays, show non-zero values only */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct __sk_buff, BTF_F_COMPACT,
+			   "(struct __sk_buff){.cb = (__u32[5])[0,0,1,0,0,],}",
+			   { .cb = { 0, 0, 1, 0, 0},});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct __sk_buff, 0,
+"(struct __sk_buff){\n"
+"	.cb = (__u32[5])[\n"
+"		0,\n"
+"		0,\n"
+"		1,\n"
+"		0,\n"
+"		0,\n"
+"	],\n"
+"}",
+			   { .cb = { 0, 0, 1, 0, 0},});
+
+	/* struct with bitfields */
+	TEST_BTF_DUMP_DATA_C(btf, d, str, struct bpf_insn, BTF_F_COMPACT,
+		{.code = (__u8)1,.dst_reg = (__u8)0x2,.src_reg = (__u8)0x3,.off = (__s16)4,.imm = (__s32)5,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_insn,
+			   BTF_F_COMPACT | BTF_F_NONAME,
+			   "{1,0x2,0x3,4,5,}",
+			   { .code = 1, .dst_reg = 0x2, .src_reg = 0x3, .off = 4,
+			     .imm = 5,});
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_insn, 0,
+"(struct bpf_insn){\n"
+"	.code = (__u8)1,\n"
+"	.dst_reg = (__u8)0x2,\n"
+"	.src_reg = (__u8)0x3,\n"
+"	.off = (__s16)4,\n"
+"	.imm = (__s32)5,\n"
+"}",
+			   {.code = 1, .dst_reg = 2, .src_reg = 3, .off = 4, .imm = 5});
+
+	/* zeroed bitfields should not be displayed */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_insn, BTF_F_COMPACT,
+			   "(struct bpf_insn){.dst_reg = (__u8)0x1,}",
+			   { .code = 0, .dst_reg = 1});
+
+	/* struct with enum bitfield */
+	type_id = btf__find_by_name(btf, "fs_context");
+	if (CHECK(type_id <= 0, "find fs_context",
+		  "no 'struct fs_context' in BTF: %d\n", type_id))
+		return;
+	type_sz = btf__resolve_size(btf, type_id);
+	str[0] = '\0';
+
+	opts.emit_zeroes = true;
+	ret = btf_dump__dump_type_data(d, type_id, zero_data, type_sz, &opts);
+	if (CHECK(ret != type_sz,
+		  "dump fs_context is successful",
+		  "unexpected return value dumping fs_context '%s': %d\n",
+		  str, ret))
+		return;
+
+	if (CHECK(strstr(str, "FS_CONTEXT_FOR_MOUNT") == NULL,
+		  "verify enum value shown for bitfield",
+		  "bitfield value not present in '%s'\n", str))
+		return;
+
+	/* struct with nested anon union */
+	TEST_BTF_DUMP_DATA(btf, d, str, struct bpf_sock_ops, BTF_F_COMPACT,
+			   "(struct bpf_sock_ops){.op = (__u32)1,(union){.args = (__u32[4])[1,2,3,4,],.reply = (__u32)1,.replylong = (__u32[4])[1,2,3,4,],},}",
+			   { .op = 1, .args = { 1, 2, 3, 4}});
+
+	/* union with nested struct */
+	TEST_BTF_DUMP_DATA(btf, d, str, union bpf_iter_link_info, BTF_F_COMPACT,
+			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},}",
+			   { .map = { .map_fd = 1 }});
+
+	/* struct skb with nested structs/unions; because type output is so
+	 * complex, we don't do a string comparison, just verify we return
+	 * the type size as the amount of data displayed.
+	 */
+	type_id = btf__find_by_name(btf, "sk_buff");
+	if (CHECK(type_id <= 0, "find type id",
+		  "no 'struct sk_buff' in BTF: %d\n", type_id))
+		return;
+	type_sz = btf__resolve_size(btf, type_id);
+	str[0] = '\0';
+
+	ret = btf_dump__dump_type_data(d, type_id, skb, type_sz, &opts);
+	if (CHECK(ret != type_sz,
+		  "dump sk_buff is successful",
+		  "unexpected return value dumping sk_buff '%s': %d\n",
+		  str, ret))
+		return;
+
+	/* overflow bpf_sock_ops struct with final element nonzero/zero.
+	 * Regardless of the value of the final field, we don't have all the
+	 * data we need to display it, so we should trigger an overflow.
+	 * In other words oveflow checking should trump "is field zero?"
+	 * checks because if we've overflowed, it shouldn't matter what the
+	 * field is - we can't trust its value so shouldn't display it.
+	 */
+	TEST_BTF_DUMP_DATA_OVER(btf, d, str, struct bpf_sock_ops,
+				sizeof(struct bpf_sock_ops) - 1,
+				"(struct bpf_sock_ops){\n\t.op = (__u32)1,\n",
+				{ .op = 1, .skb_tcp_flags = 2});
+	TEST_BTF_DUMP_DATA_OVER(btf, d, str, struct bpf_sock_ops,
+				sizeof(struct bpf_sock_ops) - 1,
+				"(struct bpf_sock_ops){\n\t.op = (__u32)1,\n",
+				{ .op = 1, .skb_tcp_flags = 0});
+}
+
+static void test_btf_dump_var_data(struct btf *btf, struct btf_dump *d,
+				   char *str)
+{
+	TEST_BTF_DUMP_VAR(btf, d, str, "cpu_number", int, BTF_F_COMPACT,
+			  "int cpu_number = (int)100", 100);
+	TEST_BTF_DUMP_VAR(btf, d, str, "cpu_profile_flip", int, BTF_F_COMPACT,
+			  "static int cpu_profile_flip = (int)2", 2);
+}
+
+static void test_btf_datasec(struct btf *btf, struct btf_dump *d, char *str,
+			     const char *name, const char *expected_val,
+			     void *data, size_t data_sz)
+{
+	DECLARE_LIBBPF_OPTS(btf_dump_type_data_opts, opts);
+	int ret = 0, cmp;
+	size_t secsize;
+	__s32 type_id;
+
+	opts.compact = true;
+
+	type_id = btf__find_by_name(btf, name);
+	if (CHECK(type_id <= 0, "find type id",
+		  "no '%s' in BTF: %d\n", name, type_id))
+		return;
+
+	secsize = btf__resolve_size(btf, type_id);
+	if (CHECK(secsize != 0, "verify section size",
+		  "unexpected section size %ld for %s\n", secsize, name))
+		return;
+
+	str[0] = '\0';
+	ret = btf_dump__dump_type_data(d, type_id, data, data_sz, &opts);
+	if (CHECK(ret != 0, "btf_dump__dump_type_data",
+		  "failed/unexpected return value: %d\n", ret))
+		return;
+
+	cmp = strcmp(str, expected_val);
+	if (CHECK(cmp, "ensure expected/actual match",
+		  "'%s' does not match expected '%s': %d\n",
+		  str, expected_val, cmp))
+		return;
+}
+
+static void test_btf_dump_datasec_data(char *str)
+{
+	struct btf *btf = btf__parse("xdping_kern.o", NULL);
+	struct btf_dump_opts opts = { .ctx = str };
+	char license[4] = "GPL";
+	struct btf_dump *d;
+
+	if (CHECK(!btf, "get prog BTF", "xdping_kern.o BTF not found"))
+		return;
+
+	d = btf_dump__new(btf, NULL, &opts, btf_dump_snprintf);
+
+	if (CHECK(!d, "new dump", "could not create BTF dump"))
+		return;
+
+	test_btf_datasec(btf, d, str, "license",
+			 "SEC(\"license\") char[4] _license = (char[4])['G','P','L',];",
+			 license, sizeof(license));
+}
+
 void test_btf_dump() {
+	char str[STRSIZE];
+	struct btf_dump_opts opts = { .ctx = str };
+	struct btf_dump *d;
+	struct btf *btf;
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(btf_dump_test_cases); i++) {
@@ -245,4 +859,34 @@  void test_btf_dump() {
 	}
 	if (test__start_subtest("btf_dump: incremental"))
 		test_btf_dump_incremental();
+
+	btf = libbpf_find_kernel_btf();
+	if (CHECK(!btf, "get kernel BTF", "no kernel BTF found"))
+		return;
+
+	d = btf_dump__new(btf, NULL, &opts, btf_dump_snprintf);
+
+	if (CHECK(!d, "new dump", "could not create BTF dump"))
+		return;
+
+	/* Verify type display for various types. */
+	if (test__start_subtest("btf_dump: int_data"))
+		test_btf_dump_int_data(btf, d, str);
+	if (test__start_subtest("btf_dump: float_data"))
+		test_btf_dump_float_data(btf, d, str);
+	if (test__start_subtest("btf_dump: char_data"))
+		test_btf_dump_char_data(btf, d, str);
+	if (test__start_subtest("btf_dump: typedef_data"))
+		test_btf_dump_typedef_data(btf, d, str);
+	if (test__start_subtest("btf_dump: enum_data"))
+		test_btf_dump_enum_data(btf, d, str);
+	if (test__start_subtest("btf_dump: struct_data"))
+		test_btf_dump_struct_data(btf, d, str);
+	if (test__start_subtest("btf_dump: var_data"))
+		test_btf_dump_var_data(btf, d, str);
+	btf_dump__free(d);
+	btf__free(btf);
+
+	if (test__start_subtest("btf_dump: datasec_data"))
+		test_btf_dump_datasec_data(str);
 }