root/tools/testing/selftests/bpf/btf_helpers.c
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Facebook */
#include <stdio.h>
#include <errno.h>
#include <bpf/btf.h>
#include <bpf/libbpf.h>
#include "test_progs.h"

static const char * const btf_kind_str_mapping[] = {
        [BTF_KIND_UNKN]         = "UNKNOWN",
        [BTF_KIND_INT]          = "INT",
        [BTF_KIND_PTR]          = "PTR",
        [BTF_KIND_ARRAY]        = "ARRAY",
        [BTF_KIND_STRUCT]       = "STRUCT",
        [BTF_KIND_UNION]        = "UNION",
        [BTF_KIND_ENUM]         = "ENUM",
        [BTF_KIND_FWD]          = "FWD",
        [BTF_KIND_TYPEDEF]      = "TYPEDEF",
        [BTF_KIND_VOLATILE]     = "VOLATILE",
        [BTF_KIND_CONST]        = "CONST",
        [BTF_KIND_RESTRICT]     = "RESTRICT",
        [BTF_KIND_FUNC]         = "FUNC",
        [BTF_KIND_FUNC_PROTO]   = "FUNC_PROTO",
        [BTF_KIND_VAR]          = "VAR",
        [BTF_KIND_DATASEC]      = "DATASEC",
        [BTF_KIND_FLOAT]        = "FLOAT",
        [BTF_KIND_DECL_TAG]     = "DECL_TAG",
        [BTF_KIND_TYPE_TAG]     = "TYPE_TAG",
        [BTF_KIND_ENUM64]       = "ENUM64",
};

static const char *btf_kind_str(__u16 kind)
{
        if (kind > BTF_KIND_ENUM64)
                return "UNKNOWN";
        return btf_kind_str_mapping[kind];
}

static const char *btf_int_enc_str(__u8 encoding)
{
        switch (encoding) {
        case 0:
                return "(none)";
        case BTF_INT_SIGNED:
                return "SIGNED";
        case BTF_INT_CHAR:
                return "CHAR";
        case BTF_INT_BOOL:
                return "BOOL";
        default:
                return "UNKN";
        }
}

static const char *btf_var_linkage_str(__u32 linkage)
{
        switch (linkage) {
        case BTF_VAR_STATIC:
                return "static";
        case BTF_VAR_GLOBAL_ALLOCATED:
                return "global-alloc";
        default:
                return "(unknown)";
        }
}

static const char *btf_func_linkage_str(const struct btf_type *t)
{
        switch (btf_vlen(t)) {
        case BTF_FUNC_STATIC:
                return "static";
        case BTF_FUNC_GLOBAL:
                return "global";
        case BTF_FUNC_EXTERN:
                return "extern";
        default:
                return "(unknown)";
        }
}

static const char *btf_str(const struct btf *btf, __u32 off)
{
        if (!off)
                return "(anon)";
        return btf__str_by_offset(btf, off) ?: "(invalid)";
}

int fprintf_btf_type_raw(FILE *out, const struct btf *btf, __u32 id)
{
        const struct btf_type *t;
        int kind, i;
        __u32 vlen;

        t = btf__type_by_id(btf, id);
        if (!t)
                return -EINVAL;

        vlen = btf_vlen(t);
        kind = btf_kind(t);

        fprintf(out, "[%u] %s '%s'", id, btf_kind_str(kind), btf_str(btf, t->name_off));

        switch (kind) {
        case BTF_KIND_INT:
                fprintf(out, " size=%u bits_offset=%u nr_bits=%u encoding=%s",
                        t->size, btf_int_offset(t), btf_int_bits(t),
                        btf_int_enc_str(btf_int_encoding(t)));
                break;
        case BTF_KIND_PTR:
        case BTF_KIND_CONST:
        case BTF_KIND_VOLATILE:
        case BTF_KIND_RESTRICT:
        case BTF_KIND_TYPEDEF:
        case BTF_KIND_TYPE_TAG:
                fprintf(out, " type_id=%u", t->type);
                break;
        case BTF_KIND_ARRAY: {
                const struct btf_array *arr = btf_array(t);

                fprintf(out, " type_id=%u index_type_id=%u nr_elems=%u",
                        arr->type, arr->index_type, arr->nelems);
                break;
        }
        case BTF_KIND_STRUCT:
        case BTF_KIND_UNION: {
                const struct btf_member *m = btf_members(t);

                fprintf(out, " size=%u vlen=%u", t->size, vlen);
                for (i = 0; i < vlen; i++, m++) {
                        __u32 bit_off, bit_sz;

                        bit_off = btf_member_bit_offset(t, i);
                        bit_sz = btf_member_bitfield_size(t, i);
                        fprintf(out, "\n\t'%s' type_id=%u bits_offset=%u",
                                btf_str(btf, m->name_off), m->type, bit_off);
                        if (bit_sz)
                                fprintf(out, " bitfield_size=%u", bit_sz);
                }
                break;
        }
        case BTF_KIND_ENUM: {
                const struct btf_enum *v = btf_enum(t);
                const char *fmt_str;

                fmt_str = btf_kflag(t) ? "\n\t'%s' val=%d" : "\n\t'%s' val=%u";
                fprintf(out, " encoding=%s size=%u vlen=%u",
                        btf_kflag(t) ? "SIGNED" : "UNSIGNED", t->size, vlen);
                for (i = 0; i < vlen; i++, v++) {
                        fprintf(out, fmt_str,
                                btf_str(btf, v->name_off), v->val);
                }
                break;
        }
        case BTF_KIND_ENUM64: {
                const struct btf_enum64 *v = btf_enum64(t);
                const char *fmt_str;

                fmt_str = btf_kflag(t) ? "\n\t'%s' val=%lld" : "\n\t'%s' val=%llu";

                fprintf(out, " encoding=%s size=%u vlen=%u",
                        btf_kflag(t) ? "SIGNED" : "UNSIGNED", t->size, vlen);
                for (i = 0; i < vlen; i++, v++) {
                        fprintf(out, fmt_str,
                                btf_str(btf, v->name_off),
                                ((__u64)v->val_hi32 << 32) | v->val_lo32);
                }
                break;
        }
        case BTF_KIND_FWD:
                fprintf(out, " fwd_kind=%s", btf_kflag(t) ? "union" : "struct");
                break;
        case BTF_KIND_FUNC:
                fprintf(out, " type_id=%u linkage=%s", t->type, btf_func_linkage_str(t));
                break;
        case BTF_KIND_FUNC_PROTO: {
                const struct btf_param *p = btf_params(t);

                fprintf(out, " ret_type_id=%u vlen=%u", t->type, vlen);
                for (i = 0; i < vlen; i++, p++) {
                        fprintf(out, "\n\t'%s' type_id=%u",
                                btf_str(btf, p->name_off), p->type);
                }
                break;
        }
        case BTF_KIND_VAR:
                fprintf(out, " type_id=%u, linkage=%s",
                        t->type, btf_var_linkage_str(btf_var(t)->linkage));
                break;
        case BTF_KIND_DATASEC: {
                const struct btf_var_secinfo *v = btf_var_secinfos(t);

                fprintf(out, " size=%u vlen=%u", t->size, vlen);
                for (i = 0; i < vlen; i++, v++) {
                        fprintf(out, "\n\ttype_id=%u offset=%u size=%u",
                                v->type, v->offset, v->size);
                }
                break;
        }
        case BTF_KIND_FLOAT:
                fprintf(out, " size=%u", t->size);
                break;
        case BTF_KIND_DECL_TAG:
                fprintf(out, " type_id=%u component_idx=%d",
                        t->type, btf_decl_tag(t)->component_idx);
                break;
        default:
                break;
        }

        return 0;
}

/* Print raw BTF type dump into a local buffer and return string pointer back.
 * Buffer *will* be overwritten by subsequent btf_type_raw_dump() calls
 */
const char *btf_type_raw_dump(const struct btf *btf, int type_id)
{
        static char buf[16 * 1024];
        FILE *buf_file;

        buf_file = fmemopen(buf, sizeof(buf) - 1, "w");
        if (!buf_file) {
                fprintf(stderr, "Failed to open memstream: %d\n", errno);
                return NULL;
        }

        fprintf_btf_type_raw(buf_file, btf, type_id);
        fflush(buf_file);
        fclose(buf_file);

        return buf;
}

int btf_validate_raw(struct btf *btf, int nr_types, const char *exp_types[])
{
        int i;
        bool ok = true;

        ASSERT_EQ(btf__type_cnt(btf) - 1, nr_types, "btf_nr_types");

        for (i = 1; i <= nr_types; i++) {
                if (!ASSERT_STREQ(btf_type_raw_dump(btf, i), exp_types[i - 1], "raw_dump"))
                        ok = false;
        }

        return ok;
}

static void btf_dump_printf(void *ctx, const char *fmt, va_list args)
{
        vfprintf(ctx, fmt, args);
}

/* Print BTF-to-C dump into a local buffer and return string pointer back.
 * Buffer *will* be overwritten by subsequent btf_type_raw_dump() calls
 */
const char *btf_type_c_dump(const struct btf *btf)
{
        static char buf[16 * 1024];
        FILE *buf_file;
        struct btf_dump *d = NULL;
        int err, i;

        buf_file = fmemopen(buf, sizeof(buf) - 1, "w");
        if (!buf_file) {
                fprintf(stderr, "Failed to open memstream: %d\n", errno);
                return NULL;
        }

        d = btf_dump__new(btf, btf_dump_printf, buf_file, NULL);
        if (libbpf_get_error(d)) {
                fprintf(stderr, "Failed to create btf_dump instance: %ld\n", libbpf_get_error(d));
                goto err_out;
        }

        for (i = 1; i < btf__type_cnt(btf); i++) {
                err = btf_dump__dump_type(d, i);
                if (err) {
                        fprintf(stderr, "Failed to dump type [%d]: %d\n", i, err);
                        goto err_out;
                }
        }

        btf_dump__free(d);
        fflush(buf_file);
        fclose(buf_file);
        return buf;
err_out:
        btf_dump__free(d);
        fclose(buf_file);
        return NULL;
}