1 files changed, 251 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..1e7c61922
--- /dev/null
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018 Facebook */
+
+#include <ctype.h>
+#include <stdio.h> /* for (FILE *) used by json_writer */
+#include <string.h>
+#include <asm/byteorder.h>
+#include <linux/bitops.h>
+#include <linux/btf.h>
+#include <linux/err.h>
+
+#include "btf.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 void btf_dumper_ptr(const void *data, json_writer_t *jw,
+			   bool is_plain_text)
+{
+	if (is_plain_text)
+		jsonw_printf(jw, "%p", *(void **)data);
+	else
+		jsonw_printf(jw, "%lu", *(unsigned long *)data);
+}
+
+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 void btf_dumper_enum(const void *data, json_writer_t *jw)
+{
+	jsonw_printf(jw, "%d", *(int *)data);
+}
+
+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;
+
+	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_dumper_int_bits(__u32 int_type, __u8 bit_offset,
+				const void *data, json_writer_t *jw,
+				bool is_plain_text)
+{
+	int left_shift_bits, right_shift_bits;
+	int nr_bits = BTF_INT_BITS(int_type);
+	int total_bits_offset;
+	int bytes_to_copy;
+	int bits_to_copy;
+	__u64 print_num;
+
+	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);
+	bits_to_copy = bit_offset + nr_bits;
+	bytes_to_copy = BITS_ROUNDUP_BYTES(bits_to_copy);
+
+	print_num = 0;
+	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 = 64 - bits_to_copy;
+#else
+#error neither big nor little endian
+#endif
+	right_shift_bits = 64 - nr_bits;
+
+	print_num <<= left_shift_bits;
+	print_num >>= right_shift_bits;
+	if (is_plain_text)
+		jsonw_printf(jw, "0x%llx", print_num);
+	else
+		jsonw_printf(jw, "%llu", print_num);
+}
+
+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;
+	}
+
+	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, *(int *)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 ret = 0;
+	int i, vlen;
+
+	t = btf__type_by_id(d->btf, type_id);
+	if (!t)
+		return -EINVAL;
+
+	vlen = BTF_INFO_VLEN(t->info);
+	jsonw_start_object(d->jw);
+	m = (struct btf_member *)(t + 1);
+
+	for (i = 0; i < vlen; i++) {
+		data_off = data + BITS_ROUNDDOWN_BYTES(m[i].offset);
+		jsonw_name(d->jw, btf__name_by_offset(d->btf, m[i].name_off));
+		ret = btf_dumper_do_type(d, m[i].type,
+					 BITS_PER_BYTE_MASKED(m[i].offset),
+					 data_off);
+		if (ret)
+			break;
+	}
+
+	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:
+		btf_dumper_enum(data, d->jw);
+		return 0;
+	case BTF_KIND_PTR:
+		btf_dumper_ptr(data, d->jw, d->is_plain_text);
+		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);
+	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);
+}