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c93cc69004
Add new `btf dump` sub-command to bpftool. It allows to dump human-readable low-level BTF types representation of BTF types. BTF can be retrieved from few different sources: - from BTF object by ID; - from PROG, if it has associated BTF; - from MAP, if it has associated BTF data; it's possible to narrow down types to either key type, value type, both, or all BTF types; - from ELF file (.BTF section). Output format mostly follows BPF verifier log format with few notable exceptions: - all the type/field/param/etc names are enclosed in single quotes to allow easier grepping and to stand out a little bit more; - FUNC_PROTO output follows STRUCT/UNION/ENUM format of having one line per each argument; this is more uniform and allows easy grepping, as opposed to succinct, but inconvenient format that BPF verifier log is using. Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Song Liu <songliubraving@fb.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
587 lines
13 KiB
C
587 lines
13 KiB
C
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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/* Copyright (C) 2019 Facebook */
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#include <errno.h>
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#include <fcntl.h>
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#include <linux/err.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <gelf.h>
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#include <bpf.h>
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#include <linux/btf.h>
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#include "btf.h"
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#include "json_writer.h"
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#include "main.h"
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static const char * const btf_kind_str[NR_BTF_KINDS] = {
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[BTF_KIND_UNKN] = "UNKNOWN",
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[BTF_KIND_INT] = "INT",
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[BTF_KIND_PTR] = "PTR",
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[BTF_KIND_ARRAY] = "ARRAY",
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[BTF_KIND_STRUCT] = "STRUCT",
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[BTF_KIND_UNION] = "UNION",
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[BTF_KIND_ENUM] = "ENUM",
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[BTF_KIND_FWD] = "FWD",
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[BTF_KIND_TYPEDEF] = "TYPEDEF",
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[BTF_KIND_VOLATILE] = "VOLATILE",
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[BTF_KIND_CONST] = "CONST",
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[BTF_KIND_RESTRICT] = "RESTRICT",
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[BTF_KIND_FUNC] = "FUNC",
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[BTF_KIND_FUNC_PROTO] = "FUNC_PROTO",
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[BTF_KIND_VAR] = "VAR",
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[BTF_KIND_DATASEC] = "DATASEC",
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};
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static const char *btf_int_enc_str(__u8 encoding)
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{
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switch (encoding) {
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case 0:
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return "(none)";
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case BTF_INT_SIGNED:
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return "SIGNED";
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case BTF_INT_CHAR:
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return "CHAR";
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case BTF_INT_BOOL:
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return "BOOL";
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default:
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return "UNKN";
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}
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}
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static const char *btf_var_linkage_str(__u32 linkage)
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{
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switch (linkage) {
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case BTF_VAR_STATIC:
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return "static";
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case BTF_VAR_GLOBAL_ALLOCATED:
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return "global-alloc";
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default:
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return "(unknown)";
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}
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}
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static const char *btf_str(const struct btf *btf, __u32 off)
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{
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if (!off)
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return "(anon)";
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return btf__name_by_offset(btf, off) ? : "(invalid)";
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}
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static int dump_btf_type(const struct btf *btf, __u32 id,
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const struct btf_type *t)
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{
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json_writer_t *w = json_wtr;
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int kind, safe_kind;
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kind = BTF_INFO_KIND(t->info);
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safe_kind = kind <= BTF_KIND_MAX ? kind : BTF_KIND_UNKN;
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if (json_output) {
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jsonw_start_object(w);
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jsonw_uint_field(w, "id", id);
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jsonw_string_field(w, "kind", btf_kind_str[safe_kind]);
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jsonw_string_field(w, "name", btf_str(btf, t->name_off));
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} else {
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printf("[%u] %s '%s'", id, btf_kind_str[safe_kind],
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btf_str(btf, t->name_off));
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}
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switch (BTF_INFO_KIND(t->info)) {
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case BTF_KIND_INT: {
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__u32 v = *(__u32 *)(t + 1);
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const char *enc;
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enc = btf_int_enc_str(BTF_INT_ENCODING(v));
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if (json_output) {
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jsonw_uint_field(w, "size", t->size);
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jsonw_uint_field(w, "bits_offset", BTF_INT_OFFSET(v));
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jsonw_uint_field(w, "nr_bits", BTF_INT_BITS(v));
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jsonw_string_field(w, "encoding", enc);
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} else {
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printf(" size=%u bits_offset=%u nr_bits=%u encoding=%s",
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t->size, BTF_INT_OFFSET(v), BTF_INT_BITS(v),
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enc);
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}
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break;
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}
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case BTF_KIND_PTR:
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case BTF_KIND_CONST:
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case BTF_KIND_VOLATILE:
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case BTF_KIND_RESTRICT:
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case BTF_KIND_TYPEDEF:
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if (json_output)
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jsonw_uint_field(w, "type_id", t->type);
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else
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printf(" type_id=%u", t->type);
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break;
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case BTF_KIND_ARRAY: {
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const struct btf_array *arr = (const void *)(t + 1);
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if (json_output) {
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jsonw_uint_field(w, "type_id", arr->type);
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jsonw_uint_field(w, "index_type_id", arr->index_type);
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jsonw_uint_field(w, "nr_elems", arr->nelems);
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} else {
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printf(" type_id=%u index_type_id=%u nr_elems=%u",
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arr->type, arr->index_type, arr->nelems);
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}
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break;
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}
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case BTF_KIND_STRUCT:
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case BTF_KIND_UNION: {
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const struct btf_member *m = (const void *)(t + 1);
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__u16 vlen = BTF_INFO_VLEN(t->info);
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int i;
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if (json_output) {
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jsonw_uint_field(w, "size", t->size);
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jsonw_uint_field(w, "vlen", vlen);
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jsonw_name(w, "members");
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jsonw_start_array(w);
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} else {
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printf(" size=%u vlen=%u", t->size, vlen);
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}
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for (i = 0; i < vlen; i++, m++) {
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const char *name = btf_str(btf, m->name_off);
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__u32 bit_off, bit_sz;
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if (BTF_INFO_KFLAG(t->info)) {
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bit_off = BTF_MEMBER_BIT_OFFSET(m->offset);
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bit_sz = BTF_MEMBER_BITFIELD_SIZE(m->offset);
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} else {
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bit_off = m->offset;
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bit_sz = 0;
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}
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if (json_output) {
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jsonw_start_object(w);
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jsonw_string_field(w, "name", name);
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jsonw_uint_field(w, "type_id", m->type);
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jsonw_uint_field(w, "bits_offset", bit_off);
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if (bit_sz) {
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jsonw_uint_field(w, "bitfield_size",
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bit_sz);
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}
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jsonw_end_object(w);
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} else {
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printf("\n\t'%s' type_id=%u bits_offset=%u",
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name, m->type, bit_off);
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if (bit_sz)
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printf(" bitfield_size=%u", bit_sz);
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}
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}
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if (json_output)
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jsonw_end_array(w);
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break;
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}
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case BTF_KIND_ENUM: {
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const struct btf_enum *v = (const void *)(t + 1);
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__u16 vlen = BTF_INFO_VLEN(t->info);
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int i;
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if (json_output) {
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jsonw_uint_field(w, "size", t->size);
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jsonw_uint_field(w, "vlen", vlen);
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jsonw_name(w, "values");
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jsonw_start_array(w);
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} else {
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printf(" size=%u vlen=%u", t->size, vlen);
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}
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for (i = 0; i < vlen; i++, v++) {
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const char *name = btf_str(btf, v->name_off);
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if (json_output) {
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jsonw_start_object(w);
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jsonw_string_field(w, "name", name);
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jsonw_uint_field(w, "val", v->val);
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jsonw_end_object(w);
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} else {
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printf("\n\t'%s' val=%u", name, v->val);
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}
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}
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if (json_output)
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jsonw_end_array(w);
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break;
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}
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case BTF_KIND_FWD: {
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const char *fwd_kind = BTF_INFO_KIND(t->info) ? "union"
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: "struct";
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if (json_output)
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jsonw_string_field(w, "fwd_kind", fwd_kind);
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else
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printf(" fwd_kind=%s", fwd_kind);
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break;
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}
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case BTF_KIND_FUNC:
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if (json_output)
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jsonw_uint_field(w, "type_id", t->type);
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else
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printf(" type_id=%u", t->type);
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break;
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case BTF_KIND_FUNC_PROTO: {
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const struct btf_param *p = (const void *)(t + 1);
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__u16 vlen = BTF_INFO_VLEN(t->info);
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int i;
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if (json_output) {
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jsonw_uint_field(w, "ret_type_id", t->type);
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jsonw_uint_field(w, "vlen", vlen);
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jsonw_name(w, "params");
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jsonw_start_array(w);
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} else {
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printf(" ret_type_id=%u vlen=%u", t->type, vlen);
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}
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for (i = 0; i < vlen; i++, p++) {
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const char *name = btf_str(btf, p->name_off);
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if (json_output) {
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jsonw_start_object(w);
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jsonw_string_field(w, "name", name);
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jsonw_uint_field(w, "type_id", p->type);
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jsonw_end_object(w);
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} else {
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printf("\n\t'%s' type_id=%u", name, p->type);
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}
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}
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if (json_output)
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jsonw_end_array(w);
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break;
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}
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case BTF_KIND_VAR: {
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const struct btf_var *v = (const void *)(t + 1);
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const char *linkage;
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linkage = btf_var_linkage_str(v->linkage);
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if (json_output) {
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jsonw_uint_field(w, "type_id", t->type);
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jsonw_string_field(w, "linkage", linkage);
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} else {
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printf(" type_id=%u, linkage=%s", t->type, linkage);
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}
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break;
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}
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case BTF_KIND_DATASEC: {
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const struct btf_var_secinfo *v = (const void *)(t+1);
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__u16 vlen = BTF_INFO_VLEN(t->info);
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int i;
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if (json_output) {
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jsonw_uint_field(w, "size", t->size);
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jsonw_uint_field(w, "vlen", vlen);
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jsonw_name(w, "vars");
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jsonw_start_array(w);
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} else {
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printf(" size=%u vlen=%u", t->size, vlen);
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}
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for (i = 0; i < vlen; i++, v++) {
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if (json_output) {
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jsonw_start_object(w);
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jsonw_uint_field(w, "type_id", v->type);
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jsonw_uint_field(w, "offset", v->offset);
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jsonw_uint_field(w, "size", v->size);
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jsonw_end_object(w);
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} else {
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printf("\n\ttype_id=%u offset=%u size=%u",
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v->type, v->offset, v->size);
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}
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}
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if (json_output)
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jsonw_end_array(w);
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break;
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}
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default:
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break;
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}
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if (json_output)
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jsonw_end_object(json_wtr);
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else
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printf("\n");
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return 0;
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}
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static int dump_btf_raw(const struct btf *btf,
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__u32 *root_type_ids, int root_type_cnt)
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{
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const struct btf_type *t;
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int i;
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if (json_output) {
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jsonw_start_object(json_wtr);
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jsonw_name(json_wtr, "types");
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jsonw_start_array(json_wtr);
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}
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if (root_type_cnt) {
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for (i = 0; i < root_type_cnt; i++) {
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t = btf__type_by_id(btf, root_type_ids[i]);
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dump_btf_type(btf, root_type_ids[i], t);
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}
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} else {
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int cnt = btf__get_nr_types(btf);
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for (i = 1; i <= cnt; i++) {
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t = btf__type_by_id(btf, i);
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dump_btf_type(btf, i, t);
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}
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}
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if (json_output) {
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jsonw_end_array(json_wtr);
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jsonw_end_object(json_wtr);
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}
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return 0;
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}
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static bool check_btf_endianness(GElf_Ehdr *ehdr)
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{
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static unsigned int const endian = 1;
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switch (ehdr->e_ident[EI_DATA]) {
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case ELFDATA2LSB:
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return *(unsigned char const *)&endian == 1;
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case ELFDATA2MSB:
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return *(unsigned char const *)&endian == 0;
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default:
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return 0;
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}
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}
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static int btf_load_from_elf(const char *path, struct btf **btf)
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{
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int err = -1, fd = -1, idx = 0;
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Elf_Data *btf_data = NULL;
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Elf_Scn *scn = NULL;
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Elf *elf = NULL;
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GElf_Ehdr ehdr;
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if (elf_version(EV_CURRENT) == EV_NONE) {
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p_err("failed to init libelf for %s", path);
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return -1;
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}
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fd = open(path, O_RDONLY);
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if (fd < 0) {
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p_err("failed to open %s: %s", path, strerror(errno));
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return -1;
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}
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elf = elf_begin(fd, ELF_C_READ, NULL);
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if (!elf) {
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p_err("failed to open %s as ELF file", path);
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goto done;
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}
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if (!gelf_getehdr(elf, &ehdr)) {
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p_err("failed to get EHDR from %s", path);
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goto done;
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}
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if (!check_btf_endianness(&ehdr)) {
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p_err("non-native ELF endianness is not supported");
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goto done;
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}
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if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {
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p_err("failed to get e_shstrndx from %s\n", path);
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goto done;
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}
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while ((scn = elf_nextscn(elf, scn)) != NULL) {
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GElf_Shdr sh;
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char *name;
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idx++;
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if (gelf_getshdr(scn, &sh) != &sh) {
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p_err("failed to get section(%d) header from %s",
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idx, path);
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goto done;
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}
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name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
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if (!name) {
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p_err("failed to get section(%d) name from %s",
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idx, path);
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goto done;
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}
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if (strcmp(name, BTF_ELF_SEC) == 0) {
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btf_data = elf_getdata(scn, 0);
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if (!btf_data) {
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p_err("failed to get section(%d, %s) data from %s",
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idx, name, path);
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goto done;
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}
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break;
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}
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}
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if (!btf_data) {
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p_err("%s ELF section not found in %s", BTF_ELF_SEC, path);
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goto done;
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}
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*btf = btf__new(btf_data->d_buf, btf_data->d_size);
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if (IS_ERR(*btf)) {
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err = PTR_ERR(*btf);
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*btf = NULL;
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p_err("failed to load BTF data from %s: %s",
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path, strerror(err));
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goto done;
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}
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err = 0;
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done:
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if (err) {
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if (*btf) {
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btf__free(*btf);
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*btf = NULL;
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}
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}
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if (elf)
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elf_end(elf);
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close(fd);
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return err;
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}
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static int do_dump(int argc, char **argv)
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{
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struct btf *btf = NULL;
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__u32 root_type_ids[2];
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int root_type_cnt = 0;
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__u32 btf_id = -1;
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const char *src;
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int fd = -1;
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int err;
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if (!REQ_ARGS(2)) {
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usage();
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return -1;
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}
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src = GET_ARG();
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if (is_prefix(src, "map")) {
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struct bpf_map_info info = {};
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__u32 len = sizeof(info);
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if (!REQ_ARGS(2)) {
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usage();
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return -1;
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}
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fd = map_parse_fd_and_info(&argc, &argv, &info, &len);
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if (fd < 0)
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return -1;
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btf_id = info.btf_id;
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if (argc && is_prefix(*argv, "key")) {
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root_type_ids[root_type_cnt++] = info.btf_key_type_id;
|
|
NEXT_ARG();
|
|
} else if (argc && is_prefix(*argv, "value")) {
|
|
root_type_ids[root_type_cnt++] = info.btf_value_type_id;
|
|
NEXT_ARG();
|
|
} else if (argc && is_prefix(*argv, "all")) {
|
|
NEXT_ARG();
|
|
} else if (argc && is_prefix(*argv, "kv")) {
|
|
root_type_ids[root_type_cnt++] = info.btf_key_type_id;
|
|
root_type_ids[root_type_cnt++] = info.btf_value_type_id;
|
|
NEXT_ARG();
|
|
} else {
|
|
root_type_ids[root_type_cnt++] = info.btf_key_type_id;
|
|
root_type_ids[root_type_cnt++] = info.btf_value_type_id;
|
|
}
|
|
} else if (is_prefix(src, "prog")) {
|
|
struct bpf_prog_info info = {};
|
|
__u32 len = sizeof(info);
|
|
|
|
if (!REQ_ARGS(2)) {
|
|
usage();
|
|
return -1;
|
|
}
|
|
|
|
fd = prog_parse_fd(&argc, &argv);
|
|
if (fd < 0)
|
|
return -1;
|
|
|
|
err = bpf_obj_get_info_by_fd(fd, &info, &len);
|
|
if (err) {
|
|
p_err("can't get prog info: %s", strerror(errno));
|
|
goto done;
|
|
}
|
|
|
|
btf_id = info.btf_id;
|
|
} else if (is_prefix(src, "id")) {
|
|
char *endptr;
|
|
|
|
btf_id = strtoul(*argv, &endptr, 0);
|
|
if (*endptr) {
|
|
p_err("can't parse %s as ID", **argv);
|
|
return -1;
|
|
}
|
|
NEXT_ARG();
|
|
} else if (is_prefix(src, "file")) {
|
|
err = btf_load_from_elf(*argv, &btf);
|
|
if (err)
|
|
goto done;
|
|
NEXT_ARG();
|
|
} else {
|
|
err = -1;
|
|
p_err("unrecognized BTF source specifier: '%s'", src);
|
|
goto done;
|
|
}
|
|
|
|
if (!btf) {
|
|
err = btf__get_from_id(btf_id, &btf);
|
|
if (err) {
|
|
p_err("get btf by id (%u): %s", btf_id, strerror(err));
|
|
goto done;
|
|
}
|
|
if (!btf) {
|
|
err = ENOENT;
|
|
p_err("can't find btf with ID (%u)", btf_id);
|
|
goto done;
|
|
}
|
|
}
|
|
|
|
dump_btf_raw(btf, root_type_ids, root_type_cnt);
|
|
|
|
done:
|
|
close(fd);
|
|
btf__free(btf);
|
|
return err;
|
|
}
|
|
|
|
static int do_help(int argc, char **argv)
|
|
{
|
|
if (json_output) {
|
|
jsonw_null(json_wtr);
|
|
return 0;
|
|
}
|
|
|
|
fprintf(stderr,
|
|
"Usage: %s btf dump BTF_SRC\n"
|
|
" %s btf help\n"
|
|
"\n"
|
|
" BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n"
|
|
" " HELP_SPEC_MAP "\n"
|
|
" " HELP_SPEC_PROGRAM "\n"
|
|
" " HELP_SPEC_OPTIONS "\n"
|
|
"",
|
|
bin_name, bin_name);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct cmd cmds[] = {
|
|
{ "help", do_help },
|
|
{ "dump", do_dump },
|
|
{ 0 }
|
|
};
|
|
|
|
int do_btf(int argc, char **argv)
|
|
{
|
|
return cmd_select(cmds, argc, argv, do_help);
|
|
}
|