From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f173.google.com (mail-pf1-f173.google.com [209.85.210.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A3B33328ED for ; Mon, 17 Nov 2025 13:26:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763385996; cv=none; b=E9dU0bKKKYPnR3BdsvH5Q6AyC2UP4kvSfdrHSwI6GUum1q8LD1IKPn2GgjAjNJaFYNluZZAygCAzzSYSpGvKIPT0w2NkgsW/TCjgOCNuxAf1rORfWjBaYKtbK9GzQyN1nIAinEpx8RCztdUsk32jL1tfWh/KT2oPRPg5UYRO93k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763385996; c=relaxed/simple; bh=6VBbAusWLjZvaGOC/+K+V+im/qf4tqKKK59Uc/T8Ph0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=A30Smc9MdJVAaAB34tlp12Qfp/tmd7rhU4LPzmxcNEdXYfivYw34WvcQKPfRCuEWgkcQ6+xiFcUVU5elrJzkv6px/ok3oX/q6wHuvaGNfYgwDTxTdeJuOeInwlsFdwfdc93iM6JsrD9Lwg7r38TspTPLdgP1IbC1dF4/H90J3Og= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Hff5GoYR; arc=none smtp.client-ip=209.85.210.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Hff5GoYR" Received: by mail-pf1-f173.google.com with SMTP id d2e1a72fcca58-7ba55660769so2580329b3a.1 for ; Mon, 17 Nov 2025 05:26:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1763385993; x=1763990793; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=DBbxUx6nVTODhi42u5LXpziwCIk3CPqNxfSqUe5bn+c=; b=Hff5GoYRLNJS2BQp8bczKrl6ga8Z1VxA67Zyl9XibD6T74RYge340yv+LKxOlnjK4m RxRYjEYfiGf9BcDcbxdMPEPckM3C8jAt46ljcZ3zZsPCnmy6Qw9u7eDpUClGcodW62pA Abosi7oOSH9rIGVvhjYVUvmolmmxh/ky/rXvjLbvfHaL6laFtnCLr5kdwApvTrNBSn2j ngsG9PA1rTCtyYNntu4Jk1f2NlAGUmDxRN/2IiwtRNCgvkhjVYZaqiHJ5JDK6n48Zihw KYHgI5l1GweU3yNJhaEB9DpwVRZ+zTavsxX712DhHI1+u58gxLm5vBcaDGbwoV6eaLyV zylw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763385993; x=1763990793; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=DBbxUx6nVTODhi42u5LXpziwCIk3CPqNxfSqUe5bn+c=; b=ABpjx/Ty1TFRcMAtk50L2hOaIyxgL2vtqPbCt7kY2MztrWODTSnN4TFLp6c17W+L2n LmLX8gob4xDu3OBMR8yJh587ABMGhZ9A8zYvTdm0LwJkHFPznRlv4sva3rv1F9TJkJEG tsQiq1bNyOEtSWsJlxmX+BoDpfb98pk8VA51bhXHZxeJ3BACZLH+r/AFxEYQp548/B2s rvW32mxEyzOT4MevokHp1Kzr+aXJuuACAU+GGBm6VB5S4CbhJ7a66J6mIOgYOT2sDpBm OZbNJ/fqdod/1e4n3e/hL5oUQfbWvtMkPlgrs4pucPxRmiDn7g7W5tVNx/qtm3ewPUwo CNkw== X-Forwarded-Encrypted: i=1; AJvYcCWJXSJenVTb075X5fXuOR7V4UVfKWcuBGld43B3vqDQ6P1Yw2VsA8uj6j2OVR6dHqG3p+4=@vger.kernel.org X-Gm-Message-State: AOJu0YwDiwUsSPxooIOZr2dTXZMhWv5r7v2bYoAs0VnqDLeiRoN7IXDX E+7oXebbwKSFRVE89qcbGQLujyjKFrs6WOQ1F6Gio/4Y2QXmZnwWkdRR X-Gm-Gg: ASbGncuafr230dlFDTarOFDqGfeuhSvqrkU00+XgFTNE7SDVs0BDn7swGn2uuUyS+2O K+JUEYKfytjNb9qRfV7IToHQsD/wWzc4lRb2NLckXj1YVGLbwyjgGgnSzWuPnLoS/s6WkfZMkbu bqi9+ZUjVdG3nOMegpSF+vGduDKcT7ZfVHrov3YmJjoENxRKG401l5DbuDTbtlZqtfv54mGFZpx UVzp4BFvZrnaFLnKyA/qVIwmsZPwYcddt+vtX4fv5dsebvE8IozEggiXff8+YP2cM0570uv/xYB w2vh/V0d/hm3U1qJZAiHN0up0nHYhZE6BS6a47TpazDEbihpOu0whDPBfvLRrxpfOm/U9kal2t0 H0CMBugfmshUpizsLSkw9uALXpDOKLvJQAIyGPtAARR92AMwubfSAO122MmxjkVn35d7gKV1h2I QINPyo7Rai9UgwQdSJiV+ASsdSjrc= X-Google-Smtp-Source: AGHT+IGbXFMdLTSTTZa1RPQl3rBb9sfz0EW9VgsJegiZI/gWTT/GjQE/NwLRF8MyNLpZwsf2nDRPyQ== X-Received: by 2002:a05:6a20:729d:b0:360:1b2e:5257 with SMTP id adf61e73a8af0-3601b2e54e1mr2570118637.2.1763385993351; Mon, 17 Nov 2025 05:26:33 -0800 (PST) Received: from pengdl-pc.mioffice.cn ([43.224.245.249]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7b924cd89bcsm13220953b3a.15.2025.11.17.05.26.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Nov 2025 05:26:32 -0800 (PST) From: Donglin Peng To: ast@kernel.org Cc: eddyz87@gmail.com, andrii.nakryiko@gmail.com, zhangxiaoqin@xiaomi.com, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Donglin Peng , Alan Maguire , Song Liu Subject: [RFC PATCH v6 1/7] libbpf: Add BTF permutation support for type reordering Date: Mon, 17 Nov 2025 21:26:17 +0800 Message-Id: <20251117132623.3807094-2-dolinux.peng@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251117132623.3807094-1-dolinux.peng@gmail.com> References: <20251117132623.3807094-1-dolinux.peng@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Donglin Peng Introduce btf__permute() API to allow in-place rearrangement of BTF types. This function reorganizes BTF type order according to a provided array of type IDs, updating all type references to maintain consistency. Cc: Eduard Zingerman Cc: Alexei Starovoitov Cc: Andrii Nakryiko Cc: Alan Maguire Cc: Song Liu Cc: Xiaoqin Zhang Signed-off-by: Donglin Peng --- tools/lib/bpf/btf.c | 191 +++++++++++++++++++++++++++++++++++++++ tools/lib/bpf/btf.h | 43 +++++++++ tools/lib/bpf/libbpf.map | 1 + 3 files changed, 235 insertions(+) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 18907f0fcf9f..e3aa31c735c8 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -5829,3 +5829,194 @@ int btf__relocate(struct btf *btf, const struct btf *base_btf) btf->owns_base = false; return libbpf_err(err); } + +struct btf_permute { + struct btf *btf; + __u32 *id_map; + __u32 offs; +}; + +/* Callback function to remap individual type ID references */ +static int btf_permute_remap_type_id(__u32 *type_id, void *ctx) +{ + struct btf_permute *p = ctx; + __u32 new_type_id = *type_id; + + /* skip references that point into the base BTF */ + if (new_type_id < p->btf->start_id) + return 0; + + /* invalid reference id */ + if (new_type_id >= btf__type_cnt(p->btf)) + return -EINVAL; + + new_type_id = p->id_map[new_type_id - p->offs]; + /* reference a dropped type is not allowed */ + if (new_type_id == 0) + return -EINVAL; + + *type_id = new_type_id; + return 0; +} + +int btf__permute(struct btf *btf, __u32 *id_map, __u32 id_map_cnt, + const struct btf_permute_opts *opts) +{ + struct btf_permute p; + struct btf_ext *btf_ext; + void *next_type, *end_type; + void *nt, *new_types = NULL; + int err = 0, n, i, new_type_len; + __u32 *order_map = NULL; + __u32 offs, id, new_nr_types = 0; + + if (!OPTS_VALID(opts, btf_permute_opts)) + return libbpf_err(-EINVAL); + + if (btf__base_btf(btf)) { + /* + * For split BTF, the number of types added on the + * top of base BTF + */ + n = btf->nr_types; + offs = btf->start_id; + } else if (id_map[0] != 0) { + /* id_map[0] must be 0 for base BTF */ + err = -EINVAL; + goto done; + } else { + /* include VOID type 0 for base BTF */ + n = btf__type_cnt(btf); + offs = 0; + } + + if (id_map_cnt != n) + return libbpf_err(-EINVAL); + + /* used to record the storage sequence of types */ + order_map = calloc(n, sizeof(*id_map)); + if (!order_map) { + err = -ENOMEM; + goto done; + } + + new_types = calloc(btf->hdr->type_len, 1); + if (!new_types) { + err = -ENOMEM; + goto done; + } + + if (btf_ensure_modifiable(btf)) { + err = -ENOMEM; + goto done; + } + + for (i = 0; i < id_map_cnt; i++) { + id = id_map[i]; + /* + * 0: Drop the specified type (exclude base BTF type 0). + * For base BTF, type 0 is always preserved. + */ + if (id == 0) + continue; + /* Invalid id */ + if (id < btf->start_id || id >= btf__type_cnt(btf)) { + err = -EINVAL; + goto done; + } + id -= offs; + /* Multiple types cannot be mapped to the same ID */ + if (order_map[id]) { + err = -EINVAL; + goto done; + } + order_map[id] = i + offs; + new_nr_types = max(id + 1, new_nr_types); + } + + /* Check for missing IDs */ + for (i = offs ? 0 : 1; i < new_nr_types; i++) { + if (order_map[i] == 0) { + err = -EINVAL; + goto done; + } + } + + p.btf = btf; + p.id_map = id_map; + p.offs = offs; + nt = new_types; + for (i = offs ? 0 : 1; i < new_nr_types; i++) { + struct btf_field_iter it; + const struct btf_type *t; + __u32 *type_id; + int type_size; + + id = order_map[i]; + /* must be a valid type ID */ + t = btf__type_by_id(btf, id); + if (!t) { + err = -EINVAL; + goto done; + } + type_size = btf_type_size(t); + memcpy(nt, t, type_size); + + /* Fix up referenced IDs for BTF */ + err = btf_field_iter_init(&it, nt, BTF_FIELD_ITER_IDS); + if (err) + goto done; + while ((type_id = btf_field_iter_next(&it))) { + err = btf_permute_remap_type_id(type_id, &p); + if (err) + goto done; + } + + nt += type_size; + } + + /* Fix up referenced IDs for btf_ext */ + btf_ext = OPTS_GET(opts, btf_ext, NULL); + if (btf_ext) { + err = btf_ext_visit_type_ids(btf_ext, btf_permute_remap_type_id, &p); + if (err) + goto done; + } + + new_type_len = nt - new_types; + next_type = new_types; + end_type = next_type + new_type_len; + i = 0; + while (next_type + sizeof(struct btf_type) <= end_type) { + btf->type_offs[i++] = next_type - new_types; + next_type += btf_type_size(next_type); + } + + /* Resize */ + if (new_type_len < btf->hdr->type_len) { + void *tmp_types; + + tmp_types = realloc(new_types, new_type_len); + if (new_type_len && !tmp_types) { + err = -ENOMEM; + goto done; + } + new_types = tmp_types; + btf->nr_types = new_nr_types - (offs ? 0 : 1); + btf->type_offs_cap = btf->nr_types; + btf->types_data_cap = new_type_len; + btf->hdr->type_len = new_type_len; + btf->hdr->str_off = new_type_len; + btf->raw_size = btf->hdr->hdr_len + btf->hdr->type_len + btf->hdr->str_len; + } + + free(order_map); + free(btf->types_data); + btf->types_data = new_types; + return 0; + +done: + free(order_map); + free(new_types); + return libbpf_err(err); +} diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index ccfd905f03df..ec4e31e918c3 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -273,6 +273,49 @@ LIBBPF_API int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts); */ LIBBPF_API int btf__relocate(struct btf *btf, const struct btf *base_btf); +struct btf_permute_opts { + size_t sz; + /* optional .BTF.ext info along the main BTF info */ + struct btf_ext *btf_ext; + size_t :0; +}; +#define btf_permute_opts__last_field btf_ext + +/** + * @brief **btf__permute()** performs in-place BTF type rearrangement + * @param btf BTF object to permute + * @param id_map Array mapping original type IDs to new IDs + * @param id_map_cnt Number of elements in @id_map + * @param opts Optional parameters for BTF extension updates + * @return 0 on success, negative error code on failure + * + * **btf__permute()** rearranges BTF types according to the specified ID mapping. + * The @id_map array defines the new type ID for each original type ID. + * + * For **base BTF**: + * - @id_map must include all types from ID 0 to `btf__type_cnt(btf)-1` + * - @id_map_cnt should be `btf__type_cnt(btf)` + * - Mapping uses `id_map[original_id] = new_id` + * + * For **split BTF**: + * - @id_map should cover only split types + * - @id_map_cnt should be `btf__type_cnt(btf) - btf__type_cnt(btf__base_btf(btf))` + * - Mapping uses `id_map[original_id - btf__type_cnt(btf__base_btf(btf))] = new_id` + * + * Setting @id_map element to 0 (except `id_map[0]` for base BTF) drops the corresponding type. + * Dropped types must not be referenced by any retained types. After permutation, + * type references in BTF data and optional extension are updated automatically. + * + * Note: Dropping types may orphan some strings, requiring subsequent **btf__dedup()** + * to clean up unreferenced strings. + * + * On error, returns negative error code and sets errno: + * - `-EINVAL`: Invalid parameters or ID mapping (duplicates, out-of-range) + * - `-ENOMEM`: Memory allocation failure + */ +LIBBPF_API int btf__permute(struct btf *btf, __u32 *id_map, __u32 id_map_cnt, + const struct btf_permute_opts *opts); + struct btf_dump; struct btf_dump_opts { diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 8ed8749907d4..b778e5a5d0a8 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -451,4 +451,5 @@ LIBBPF_1.7.0 { global: bpf_map__set_exclusive_program; bpf_map__exclusive_program; + btf__permute; } LIBBPF_1.6.0; -- 2.34.1