1 files changed, 906 insertions, 0 deletions

diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
new file mode 100644
index 000000000..1b7f69714
--- /dev/null
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -0,0 +1,906 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <ctype.h>
+#include <stdio.h> /* for (FILE *) used by json_writer */
+#include <string.h>
+#include <unistd.h>
+#include <asm/byteorder.h>
+#include <linux/bitops.h>
+#include <linux/btf.h>
+#include <linux/err.h>
+#include <bpf/btf.h>
+#include <bpf/bpf.h>
+
+#include "json_writer.h"
+#include "main.h"
+
+#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
+#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
+#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
+#define BITS_ROUNDUP_BYTES(bits) \
+	(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
+
+static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
+			      __u8 bit_offset, const void *data);
+
+static int btf_dump_func(const struct btf *btf, char *func_sig,
+			 const struct btf_type *func_proto,
+			 const struct btf_type *func, int pos, int size);
+
+static int dump_prog_id_as_func_ptr(const struct btf_dumper *d,
+				    const struct btf_type *func_proto,
+				    __u32 prog_id)
+{
+	const struct btf_type *func_type;
+	int prog_fd = -1, func_sig_len;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	const char *prog_name = NULL;
+	struct btf *prog_btf = NULL;
+	struct bpf_func_info finfo;
+	__u32 finfo_rec_size;
+	char prog_str[1024];
+	int err;
+
+	/* Get the ptr's func_proto */
+	func_sig_len = btf_dump_func(d->btf, prog_str, func_proto, NULL, 0,
+				     sizeof(prog_str));
+	if (func_sig_len == -1)
+		return -1;
+
+	if (!prog_id)
+		goto print;
+
+	/* Get the bpf_prog's name.  Obtain from func_info. */
+	prog_fd = bpf_prog_get_fd_by_id(prog_id);
+	if (prog_fd < 0)
+		goto print;
+
+	err = bpf_prog_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err)
+		goto print;
+
+	if (!info.btf_id || !info.nr_func_info)
+		goto print;
+
+	finfo_rec_size = info.func_info_rec_size;
+	memset(&info, 0, sizeof(info));
+	info.nr_func_info = 1;
+	info.func_info_rec_size = finfo_rec_size;
+	info.func_info = ptr_to_u64(&finfo);
+
+	err = bpf_prog_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err)
+		goto print;
+
+	prog_btf = btf__load_from_kernel_by_id(info.btf_id);
+	if (!prog_btf)
+		goto print;
+	func_type = btf__type_by_id(prog_btf, finfo.type_id);
+	if (!func_type || !btf_is_func(func_type))
+		goto print;
+
+	prog_name = btf__name_by_offset(prog_btf, func_type->name_off);
+
+print:
+	if (!prog_id)
+		snprintf(&prog_str[func_sig_len],
+			 sizeof(prog_str) - func_sig_len, " 0");
+	else if (prog_name)
+		snprintf(&prog_str[func_sig_len],
+			 sizeof(prog_str) - func_sig_len,
+			 " %s/prog_id:%u", prog_name, prog_id);
+	else
+		snprintf(&prog_str[func_sig_len],
+			 sizeof(prog_str) - func_sig_len,
+			 " <unknown_prog_name>/prog_id:%u", prog_id);
+
+	prog_str[sizeof(prog_str) - 1] = '\0';
+	jsonw_string(d->jw, prog_str);
+	btf__free(prog_btf);
+	if (prog_fd >= 0)
+		close(prog_fd);
+	return 0;
+}
+
+static void btf_dumper_ptr(const struct btf_dumper *d,
+			   const struct btf_type *t,
+			   const void *data)
+{
+	unsigned long value = *(unsigned long *)data;
+	const struct btf_type *ptr_type;
+	__s32 ptr_type_id;
+
+	if (!d->prog_id_as_func_ptr || value > UINT32_MAX)
+		goto print_ptr_value;
+
+	ptr_type_id = btf__resolve_type(d->btf, t->type);
+	if (ptr_type_id < 0)
+		goto print_ptr_value;
+	ptr_type = btf__type_by_id(d->btf, ptr_type_id);
+	if (!ptr_type || !btf_is_func_proto(ptr_type))
+		goto print_ptr_value;
+
+	if (!dump_prog_id_as_func_ptr(d, ptr_type, value))
+		return;
+
+print_ptr_value:
+	if (d->is_plain_text)
+		jsonw_printf(d->jw, "%p", (void *)value);
+	else
+		jsonw_printf(d->jw, "%lu", value);
+}
+
+static int btf_dumper_modifier(const struct btf_dumper *d, __u32 type_id,
+			       __u8 bit_offset, const void *data)
+{
+	int actual_type_id;
+
+	actual_type_id = btf__resolve_type(d->btf, type_id);
+	if (actual_type_id < 0)
+		return actual_type_id;
+
+	return btf_dumper_do_type(d, actual_type_id, bit_offset, data);
+}
+
+static int btf_dumper_enum(const struct btf_dumper *d,
+			    const struct btf_type *t,
+			    const void *data)
+{
+	const struct btf_enum *enums = btf_enum(t);
+	__s64 value;
+	__u16 i;
+
+	switch (t->size) {
+	case 8:
+		value = *(__s64 *)data;
+		break;
+	case 4:
+		value = *(__s32 *)data;
+		break;
+	case 2:
+		value = *(__s16 *)data;
+		break;
+	case 1:
+		value = *(__s8 *)data;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	for (i = 0; i < btf_vlen(t); i++) {
+		if (value == enums[i].val) {
+			jsonw_string(d->jw,
+				     btf__name_by_offset(d->btf,
+							 enums[i].name_off));
+			return 0;
+		}
+	}
+
+	jsonw_int(d->jw, value);
+	return 0;
+}
+
+static int btf_dumper_enum64(const struct btf_dumper *d,
+			     const struct btf_type *t,
+			     const void *data)
+{
+	const struct btf_enum64 *enums = btf_enum64(t);
+	__u32 val_lo32, val_hi32;
+	__u64 value;
+	__u16 i;
+
+	value = *(__u64 *)data;
+	val_lo32 = (__u32)value;
+	val_hi32 = value >> 32;
+
+	for (i = 0; i < btf_vlen(t); i++) {
+		if (val_lo32 == enums[i].val_lo32 && val_hi32 == enums[i].val_hi32) {
+			jsonw_string(d->jw,
+				     btf__name_by_offset(d->btf,
+							 enums[i].name_off));
+			return 0;
+		}
+	}
+
+	jsonw_int(d->jw, value);
+	return 0;
+}
+
+static bool is_str_array(const struct btf *btf, const struct btf_array *arr,
+			 const char *s)
+{
+	const struct btf_type *elem_type;
+	const char *end_s;
+
+	if (!arr->nelems)
+		return false;
+
+	elem_type = btf__type_by_id(btf, arr->type);
+	/* Not skipping typedef.  typedef to char does not count as
+	 * a string now.
+	 */
+	while (elem_type && btf_is_mod(elem_type))
+		elem_type = btf__type_by_id(btf, elem_type->type);
+
+	if (!elem_type || !btf_is_int(elem_type) || elem_type->size != 1)
+		return false;
+
+	if (btf_int_encoding(elem_type) != BTF_INT_CHAR &&
+	    strcmp("char", btf__name_by_offset(btf, elem_type->name_off)))
+		return false;
+
+	end_s = s + arr->nelems;
+	while (s < end_s) {
+		if (!*s)
+			return true;
+		if (*s <= 0x1f || *s >= 0x7f)
+			return false;
+		s++;
+	}
+
+	/* '\0' is not found */
+	return false;
+}
+
+static int btf_dumper_array(const struct btf_dumper *d, __u32 type_id,
+			    const void *data)
+{
+	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
+	struct btf_array *arr = (struct btf_array *)(t + 1);
+	long long elem_size;
+	int ret = 0;
+	__u32 i;
+
+	if (is_str_array(d->btf, arr, data)) {
+		jsonw_string(d->jw, data);
+		return 0;
+	}
+
+	elem_size = btf__resolve_size(d->btf, arr->type);
+	if (elem_size < 0)
+		return elem_size;
+
+	jsonw_start_array(d->jw);
+	for (i = 0; i < arr->nelems; i++) {
+		ret = btf_dumper_do_type(d, arr->type, 0,
+					 data + i * elem_size);
+		if (ret)
+			break;
+	}
+
+	jsonw_end_array(d->jw);
+	return ret;
+}
+
+static void btf_int128_print(json_writer_t *jw, const void *data,
+			     bool is_plain_text)
+{
+	/* data points to a __int128 number.
+	 * Suppose
+	 *     int128_num = *(__int128 *)data;
+	 * The below formulas shows what upper_num and lower_num represents:
+	 *     upper_num = int128_num >> 64;
+	 *     lower_num = int128_num & 0xffffffffFFFFFFFFULL;
+	 */
+	__u64 upper_num, lower_num;
+
+#ifdef __BIG_ENDIAN_BITFIELD
+	upper_num = *(__u64 *)data;
+	lower_num = *(__u64 *)(data + 8);
+#else
+	upper_num = *(__u64 *)(data + 8);
+	lower_num = *(__u64 *)data;
+#endif
+
+	if (is_plain_text) {
+		if (upper_num == 0)
+			jsonw_printf(jw, "0x%llx", lower_num);
+		else
+			jsonw_printf(jw, "0x%llx%016llx", upper_num, lower_num);
+	} else {
+		if (upper_num == 0)
+			jsonw_printf(jw, "\"0x%llx\"", lower_num);
+		else
+			jsonw_printf(jw, "\"0x%llx%016llx\"", upper_num, lower_num);
+	}
+}
+
+static void btf_int128_shift(__u64 *print_num, __u16 left_shift_bits,
+			     __u16 right_shift_bits)
+{
+	__u64 upper_num, lower_num;
+
+#ifdef __BIG_ENDIAN_BITFIELD
+	upper_num = print_num[0];
+	lower_num = print_num[1];
+#else
+	upper_num = print_num[1];
+	lower_num = print_num[0];
+#endif
+
+	/* shake out un-needed bits by shift/or operations */
+	if (left_shift_bits >= 64) {
+		upper_num = lower_num << (left_shift_bits - 64);
+		lower_num = 0;
+	} else {
+		upper_num = (upper_num << left_shift_bits) |
+			    (lower_num >> (64 - left_shift_bits));
+		lower_num = lower_num << left_shift_bits;
+	}
+
+	if (right_shift_bits >= 64) {
+		lower_num = upper_num >> (right_shift_bits - 64);
+		upper_num = 0;
+	} else {
+		lower_num = (lower_num >> right_shift_bits) |
+			    (upper_num << (64 - right_shift_bits));
+		upper_num = upper_num >> right_shift_bits;
+	}
+
+#ifdef __BIG_ENDIAN_BITFIELD
+	print_num[0] = upper_num;
+	print_num[1] = lower_num;
+#else
+	print_num[0] = lower_num;
+	print_num[1] = upper_num;
+#endif
+}
+
+static void btf_dumper_bitfield(__u32 nr_bits, __u8 bit_offset,
+				const void *data, json_writer_t *jw,
+				bool is_plain_text)
+{
+	int left_shift_bits, right_shift_bits;
+	__u64 print_num[2] = {};
+	int bytes_to_copy;
+	int bits_to_copy;
+
+	bits_to_copy = bit_offset + nr_bits;
+	bytes_to_copy = BITS_ROUNDUP_BYTES(bits_to_copy);
+
+	memcpy(print_num, data, bytes_to_copy);
+#if defined(__BIG_ENDIAN_BITFIELD)
+	left_shift_bits = bit_offset;
+#elif defined(__LITTLE_ENDIAN_BITFIELD)
+	left_shift_bits = 128 - bits_to_copy;
+#else
+#error neither big nor little endian
+#endif
+	right_shift_bits = 128 - nr_bits;
+
+	btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
+	btf_int128_print(jw, print_num, is_plain_text);
+}
+
+
+static void btf_dumper_int_bits(__u32 int_type, __u8 bit_offset,
+				const void *data, json_writer_t *jw,
+				bool is_plain_text)
+{
+	int nr_bits = BTF_INT_BITS(int_type);
+	int total_bits_offset;
+
+	/* bits_offset is at most 7.
+	 * BTF_INT_OFFSET() cannot exceed 128 bits.
+	 */
+	total_bits_offset = bit_offset + BTF_INT_OFFSET(int_type);
+	data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
+	bit_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
+	btf_dumper_bitfield(nr_bits, bit_offset, data, jw,
+			    is_plain_text);
+}
+
+static int btf_dumper_int(const struct btf_type *t, __u8 bit_offset,
+			  const void *data, json_writer_t *jw,
+			  bool is_plain_text)
+{
+	__u32 *int_type;
+	__u32 nr_bits;
+
+	int_type = (__u32 *)(t + 1);
+	nr_bits = BTF_INT_BITS(*int_type);
+	/* if this is bit field */
+	if (bit_offset || BTF_INT_OFFSET(*int_type) ||
+	    BITS_PER_BYTE_MASKED(nr_bits)) {
+		btf_dumper_int_bits(*int_type, bit_offset, data, jw,
+				    is_plain_text);
+		return 0;
+	}
+
+	if (nr_bits == 128) {
+		btf_int128_print(jw, data, is_plain_text);
+		return 0;
+	}
+
+	switch (BTF_INT_ENCODING(*int_type)) {
+	case 0:
+		if (BTF_INT_BITS(*int_type) == 64)
+			jsonw_printf(jw, "%llu", *(__u64 *)data);
+		else if (BTF_INT_BITS(*int_type) == 32)
+			jsonw_printf(jw, "%u", *(__u32 *)data);
+		else if (BTF_INT_BITS(*int_type) == 16)
+			jsonw_printf(jw, "%hu", *(__u16 *)data);
+		else if (BTF_INT_BITS(*int_type) == 8)
+			jsonw_printf(jw, "%hhu", *(__u8 *)data);
+		else
+			btf_dumper_int_bits(*int_type, bit_offset, data, jw,
+					    is_plain_text);
+		break;
+	case BTF_INT_SIGNED:
+		if (BTF_INT_BITS(*int_type) == 64)
+			jsonw_printf(jw, "%lld", *(long long *)data);
+		else if (BTF_INT_BITS(*int_type) == 32)
+			jsonw_printf(jw, "%d", *(int *)data);
+		else if (BTF_INT_BITS(*int_type) == 16)
+			jsonw_printf(jw, "%hd", *(short *)data);
+		else if (BTF_INT_BITS(*int_type) == 8)
+			jsonw_printf(jw, "%hhd", *(char *)data);
+		else
+			btf_dumper_int_bits(*int_type, bit_offset, data, jw,
+					    is_plain_text);
+		break;
+	case BTF_INT_CHAR:
+		if (isprint(*(char *)data))
+			jsonw_printf(jw, "\"%c\"", *(char *)data);
+		else
+			if (is_plain_text)
+				jsonw_printf(jw, "0x%hhx", *(char *)data);
+			else
+				jsonw_printf(jw, "\"\\u00%02hhx\"",
+					     *(char *)data);
+		break;
+	case BTF_INT_BOOL:
+		jsonw_bool(jw, *(bool *)data);
+		break;
+	default:
+		/* shouldn't happen */
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int btf_dumper_struct(const struct btf_dumper *d, __u32 type_id,
+			     const void *data)
+{
+	const struct btf_type *t;
+	struct btf_member *m;
+	const void *data_off;
+	int kind_flag;
+	int ret = 0;
+	int i, vlen;
+
+	t = btf__type_by_id(d->btf, type_id);
+	if (!t)
+		return -EINVAL;
+
+	kind_flag = BTF_INFO_KFLAG(t->info);
+	vlen = BTF_INFO_VLEN(t->info);
+	jsonw_start_object(d->jw);
+	m = (struct btf_member *)(t + 1);
+
+	for (i = 0; i < vlen; i++) {
+		__u32 bit_offset = m[i].offset;
+		__u32 bitfield_size = 0;
+
+		if (kind_flag) {
+			bitfield_size = BTF_MEMBER_BITFIELD_SIZE(bit_offset);
+			bit_offset = BTF_MEMBER_BIT_OFFSET(bit_offset);
+		}
+
+		jsonw_name(d->jw, btf__name_by_offset(d->btf, m[i].name_off));
+		data_off = data + BITS_ROUNDDOWN_BYTES(bit_offset);
+		if (bitfield_size) {
+			btf_dumper_bitfield(bitfield_size,
+					    BITS_PER_BYTE_MASKED(bit_offset),
+					    data_off, d->jw, d->is_plain_text);
+		} else {
+			ret = btf_dumper_do_type(d, m[i].type,
+						 BITS_PER_BYTE_MASKED(bit_offset),
+						 data_off);
+			if (ret)
+				break;
+		}
+	}
+
+	jsonw_end_object(d->jw);
+
+	return ret;
+}
+
+static int btf_dumper_var(const struct btf_dumper *d, __u32 type_id,
+			  __u8 bit_offset, const void *data)
+{
+	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
+	int ret;
+
+	jsonw_start_object(d->jw);
+	jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
+	ret = btf_dumper_do_type(d, t->type, bit_offset, data);
+	jsonw_end_object(d->jw);
+
+	return ret;
+}
+
+static int btf_dumper_datasec(const struct btf_dumper *d, __u32 type_id,
+			      const void *data)
+{
+	struct btf_var_secinfo *vsi;
+	const struct btf_type *t;
+	int ret = 0, i, vlen;
+
+	t = btf__type_by_id(d->btf, type_id);
+	if (!t)
+		return -EINVAL;
+
+	vlen = BTF_INFO_VLEN(t->info);
+	vsi = (struct btf_var_secinfo *)(t + 1);
+
+	jsonw_start_object(d->jw);
+	jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
+	jsonw_start_array(d->jw);
+	for (i = 0; i < vlen; i++) {
+		ret = btf_dumper_do_type(d, vsi[i].type, 0, data + vsi[i].offset);
+		if (ret)
+			break;
+	}
+	jsonw_end_array(d->jw);
+	jsonw_end_object(d->jw);
+
+	return ret;
+}
+
+static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
+			      __u8 bit_offset, const void *data)
+{
+	const struct btf_type *t = btf__type_by_id(d->btf, type_id);
+
+	switch (BTF_INFO_KIND(t->info)) {
+	case BTF_KIND_INT:
+		return btf_dumper_int(t, bit_offset, data, d->jw,
+				     d->is_plain_text);
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		return btf_dumper_struct(d, type_id, data);
+	case BTF_KIND_ARRAY:
+		return btf_dumper_array(d, type_id, data);
+	case BTF_KIND_ENUM:
+		return btf_dumper_enum(d, t, data);
+	case BTF_KIND_ENUM64:
+		return btf_dumper_enum64(d, t, data);
+	case BTF_KIND_PTR:
+		btf_dumper_ptr(d, t, data);
+		return 0;
+	case BTF_KIND_UNKN:
+		jsonw_printf(d->jw, "(unknown)");
+		return 0;
+	case BTF_KIND_FWD:
+		/* map key or value can't be forward */
+		jsonw_printf(d->jw, "(fwd-kind-invalid)");
+		return -EINVAL;
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+		return btf_dumper_modifier(d, type_id, bit_offset, data);
+	case BTF_KIND_VAR:
+		return btf_dumper_var(d, type_id, bit_offset, data);
+	case BTF_KIND_DATASEC:
+		return btf_dumper_datasec(d, type_id, data);
+	default:
+		jsonw_printf(d->jw, "(unsupported-kind");
+		return -EINVAL;
+	}
+}
+
+int btf_dumper_type(const struct btf_dumper *d, __u32 type_id,
+		    const void *data)
+{
+	return btf_dumper_do_type(d, type_id, 0, data);
+}
+
+#define BTF_PRINT_ARG(...)						\
+	do {								\
+		pos += snprintf(func_sig + pos, size - pos,		\
+				__VA_ARGS__);				\
+		if (pos >= size)					\
+			return -1;					\
+	} while (0)
+#define BTF_PRINT_TYPE(type)					\
+	do {								\
+		pos = __btf_dumper_type_only(btf, type, func_sig,	\
+					     pos, size);		\
+		if (pos == -1)						\
+			return -1;					\
+	} while (0)
+
+static int __btf_dumper_type_only(const struct btf *btf, __u32 type_id,
+				  char *func_sig, int pos, int size)
+{
+	const struct btf_type *proto_type;
+	const struct btf_array *array;
+	const struct btf_var *var;
+	const struct btf_type *t;
+
+	if (!type_id) {
+		BTF_PRINT_ARG("void ");
+		return pos;
+	}
+
+	t = btf__type_by_id(btf, type_id);
+
+	switch (BTF_INFO_KIND(t->info)) {
+	case BTF_KIND_INT:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FLOAT:
+		BTF_PRINT_ARG("%s ", btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_STRUCT:
+		BTF_PRINT_ARG("struct %s ",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_UNION:
+		BTF_PRINT_ARG("union %s ",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		BTF_PRINT_ARG("enum %s ",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_ARRAY:
+		array = (struct btf_array *)(t + 1);
+		BTF_PRINT_TYPE(array->type);
+		BTF_PRINT_ARG("[%d]", array->nelems);
+		break;
+	case BTF_KIND_PTR:
+		BTF_PRINT_TYPE(t->type);
+		BTF_PRINT_ARG("* ");
+		break;
+	case BTF_KIND_FWD:
+		BTF_PRINT_ARG("%s %s ",
+			      BTF_INFO_KFLAG(t->info) ? "union" : "struct",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_VOLATILE:
+		BTF_PRINT_ARG("volatile ");
+		BTF_PRINT_TYPE(t->type);
+		break;
+	case BTF_KIND_CONST:
+		BTF_PRINT_ARG("const ");
+		BTF_PRINT_TYPE(t->type);
+		break;
+	case BTF_KIND_RESTRICT:
+		BTF_PRINT_ARG("restrict ");
+		BTF_PRINT_TYPE(t->type);
+		break;
+	case BTF_KIND_FUNC_PROTO:
+		pos = btf_dump_func(btf, func_sig, t, NULL, pos, size);
+		if (pos == -1)
+			return -1;
+		break;
+	case BTF_KIND_FUNC:
+		proto_type = btf__type_by_id(btf, t->type);
+		pos = btf_dump_func(btf, func_sig, proto_type, t, pos, size);
+		if (pos == -1)
+			return -1;
+		break;
+	case BTF_KIND_VAR:
+		var = (struct btf_var *)(t + 1);
+		if (var->linkage == BTF_VAR_STATIC)
+			BTF_PRINT_ARG("static ");
+		BTF_PRINT_TYPE(t->type);
+		BTF_PRINT_ARG(" %s",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_DATASEC:
+		BTF_PRINT_ARG("section (\"%s\") ",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_UNKN:
+	default:
+		return -1;
+	}
+
+	return pos;
+}
+
+static int btf_dump_func(const struct btf *btf, char *func_sig,
+			 const struct btf_type *func_proto,
+			 const struct btf_type *func, int pos, int size)
+{
+	int i, vlen;
+
+	BTF_PRINT_TYPE(func_proto->type);
+	if (func)
+		BTF_PRINT_ARG("%s(", btf__name_by_offset(btf, func->name_off));
+	else
+		BTF_PRINT_ARG("(");
+	vlen = BTF_INFO_VLEN(func_proto->info);
+	for (i = 0; i < vlen; i++) {
+		struct btf_param *arg = &((struct btf_param *)(func_proto + 1))[i];
+
+		if (i)
+			BTF_PRINT_ARG(", ");
+		if (arg->type) {
+			BTF_PRINT_TYPE(arg->type);
+			if (arg->name_off)
+				BTF_PRINT_ARG("%s",
+					      btf__name_by_offset(btf, arg->name_off));
+			else if (pos && func_sig[pos - 1] == ' ')
+				/* Remove unnecessary space for
+				 * FUNC_PROTO that does not have
+				 * arg->name_off
+				 */
+				func_sig[--pos] = '\0';
+		} else {
+			BTF_PRINT_ARG("...");
+		}
+	}
+	BTF_PRINT_ARG(")");
+
+	return pos;
+}
+
+void btf_dumper_type_only(const struct btf *btf, __u32 type_id, char *func_sig,
+			  int size)
+{
+	int err;
+
+	func_sig[0] = '\0';
+	if (!btf)
+		return;
+
+	err = __btf_dumper_type_only(btf, type_id, func_sig, 0, size);
+	if (err < 0)
+		func_sig[0] = '\0';
+}
+
+static const char *ltrim(const char *s)
+{
+	while (isspace(*s))
+		s++;
+
+	return s;
+}
+
+void btf_dump_linfo_plain(const struct btf *btf,
+			  const struct bpf_line_info *linfo,
+			  const char *prefix, bool linum)
+{
+	const char *line = btf__name_by_offset(btf, linfo->line_off);
+
+	if (!line)
+		return;
+	line = ltrim(line);
+
+	if (!prefix)
+		prefix = "";
+
+	if (linum) {
+		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
+
+		/* More forgiving on file because linum option is
+		 * expected to provide more info than the already
+		 * available src line.
+		 */
+		if (!file)
+			file = "";
+
+		printf("%s%s [file:%s line_num:%u line_col:%u]\n",
+		       prefix, line, file,
+		       BPF_LINE_INFO_LINE_NUM(linfo->line_col),
+		       BPF_LINE_INFO_LINE_COL(linfo->line_col));
+	} else {
+		printf("%s%s\n", prefix, line);
+	}
+}
+
+void btf_dump_linfo_json(const struct btf *btf,
+			 const struct bpf_line_info *linfo, bool linum)
+{
+	const char *line = btf__name_by_offset(btf, linfo->line_off);
+
+	if (line)
+		jsonw_string_field(json_wtr, "src", ltrim(line));
+
+	if (linum) {
+		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
+
+		if (file)
+			jsonw_string_field(json_wtr, "file", file);
+
+		if (BPF_LINE_INFO_LINE_NUM(linfo->line_col))
+			jsonw_int_field(json_wtr, "line_num",
+					BPF_LINE_INFO_LINE_NUM(linfo->line_col));
+
+		if (BPF_LINE_INFO_LINE_COL(linfo->line_col))
+			jsonw_int_field(json_wtr, "line_col",
+					BPF_LINE_INFO_LINE_COL(linfo->line_col));
+	}
+}
+
+static void dotlabel_puts(const char *s)
+{
+	for (; *s; ++s) {
+		switch (*s) {
+		case '\\':
+		case '"':
+		case '{':
+		case '}':
+		case '<':
+		case '>':
+		case '|':
+		case ' ':
+			putchar('\\');
+			fallthrough;
+		default:
+			putchar(*s);
+		}
+	}
+}
+
+static const char *shorten_path(const char *path)
+{
+	const unsigned int MAX_PATH_LEN = 32;
+	size_t len = strlen(path);
+	const char *shortpath;
+
+	if (len <= MAX_PATH_LEN)
+		return path;
+
+	/* Search for last '/' under the MAX_PATH_LEN limit */
+	shortpath = strchr(path + len - MAX_PATH_LEN, '/');
+	if (shortpath) {
+		if (shortpath < path + strlen("..."))
+			/* We removed a very short prefix, e.g. "/w", and we'll
+			 * make the path longer by prefixing with the ellipsis.
+			 * Not worth it, keep initial path.
+			 */
+			return path;
+		return shortpath;
+	}
+
+	/* File base name length is > MAX_PATH_LEN, search for last '/' */
+			shortpath = strrchr(path, '/');
+	if (shortpath)
+		return shortpath;
+
+	return path;
+}
+
+void btf_dump_linfo_dotlabel(const struct btf *btf,
+			     const struct bpf_line_info *linfo, bool linum)
+{
+	const char *line = btf__name_by_offset(btf, linfo->line_off);
+
+	if (!line || !strlen(line))
+		return;
+	line = ltrim(line);
+
+	if (linum) {
+		const char *file = btf__name_by_offset(btf, linfo->file_name_off);
+		const char *shortfile;
+
+		/* More forgiving on file because linum option is
+		 * expected to provide more info than the already
+		 * available src line.
+		 */
+		if (!file)
+			shortfile = "";
+		else
+			shortfile = shorten_path(file);
+
+		printf("; [%s", shortfile > file ? "..." : "");
+		dotlabel_puts(shortfile);
+		printf(" line:%u col:%u]\\l\\\n",
+		       BPF_LINE_INFO_LINE_NUM(linfo->line_col),
+		       BPF_LINE_INFO_LINE_COL(linfo->line_col));
+	}
+
+	printf("; ");
+	dotlabel_puts(line);
+	printf("\\l\\\n");
+}