From nobody Tue Dec 2 02:41:09 2025 Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) (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 573552E9ED8 for ; Wed, 19 Nov 2025 03:21:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763522507; cv=none; b=nB8iOE4XdIgGc5JOgsD7uZWdNZAdtb+KrcAKD9Dts9aoA3022mjYhazxtjArj3leIUl8TEBeN5YuCDtpIOP4paURL3lxVsnsul5poDVDzezPMQDyafqK+xFTmh/DYlk9q7acK/N1RfYCbLwyaAhZxpT05RkKgLgVHFuwPRZmZT8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763522507; c=relaxed/simple; bh=H01WYWTjit4IDrTI6i2QFoyvRtKnaGfvGo11pfu3UXc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=WqoCROlQFBLQAXuIrzlzfymAwmJ6OwPUFCRbK1656TOVmjZgwwijK01CTSw2XtvPtPKZLuOGABolgExXKorhtI0k3h5tFpXdKkqZ0l7PDEGF0DlPSBvLv7TfJbiv0b4Lq0vKUzivK3IfVSaVg+Vk1KnkgC3V5Y6Y4yzGF2CyQoo= 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=KNRXtCgG; arc=none smtp.client-ip=209.85.214.171 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="KNRXtCgG" Received: by mail-pl1-f171.google.com with SMTP id d9443c01a7336-2980d9b7df5so66644495ad.3 for ; Tue, 18 Nov 2025 19:21:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1763522503; x=1764127303; 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=j4Efz0DfhwaNbhU/ThUpGlzfbjEU0d17SrWYpmaJZf4=; b=KNRXtCgGAohG0AR7pskH6uDdatdM/pyuADSf7/3J8gz+ZlS91zMi85lbCZw0Ywa9W1 7K4TZJGgx/DdZCmn5PhDCooyZhjiXAZ5lkXugP5ET55Izf96hWQt0jzYXU7VlMYsd8oO lYJbO4uqWiqqa3aE4Z+gB0ecj/ZalXpVUcLbSh/8xHm104NYjQCqckZBbM6aT0XKONAO 0FKahA1/9uHLnZrCVRHtxxAUpFKIW/nP+GASSxdhZGFJsRaNERrd/Po5UCJ/prtWu/So kLe2E+DOUQ99MZgi1xaoJMBGw56QRRLYiikmtrvBUuF5ZXQZtvlKNnEAqZtB5D/m1lYq cX7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763522503; x=1764127303; 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=j4Efz0DfhwaNbhU/ThUpGlzfbjEU0d17SrWYpmaJZf4=; b=copzkuyCmj834abLnaiEIWzsDJiyPKkk3K1zU6tu5SJ8qkT3gsMR+M8+wGVCN773dz 4YwRHWE6Xl72dpZthYB0Ip60ZCCidKO0j1+s7oUwXmZWtKb7sfNxyVL8QG+aeVyHE/dT 9IJUUzm9EhJzHnQOwMTPa1OzmlYFTGAiqu+eMNJd1mxNeqtQKpk9hutvQuKw0/j0YxEx hxzvJBzwMGmiQeMLxcLwV1s7dOlZ/T5ZmRExa4NT3RQY2SdoAF3kjKMwNaJNvYy8kaKd RsNT+jUapQYkC1BhKwSzFk8HZy85Lq7g1huyREF5q/uTOjxyb9gGhAr2Ilm+9gTeOcVi i8qg== X-Forwarded-Encrypted: i=1; AJvYcCUzMjDEWQrKUlJeTDrqfbuTKaLQI/PlDqZ0WNL5OZi1px9k0PFnKzi+zWxRqe/AVvvexsaFjAxcz3eWtnM=@vger.kernel.org X-Gm-Message-State: AOJu0YwnBe+OTS5rpcJ7zlcZKSexfrpy6abyOf9Sp9GA1VGNabSD27Vf anyzEGeRTTMZ+00rd4CxcVlxMLtfsHFcApXRJnTsfWtJeo9qycjcG01h X-Gm-Gg: ASbGncs7EYWqOhr2Bl8TwRFGert0zhAhkF3pqQbpo86TCLi0JUfynJs+wtVUJNHuTwW 5uOdLKij2SCPnWgY8OH4swIePrps+8uzmPpKMH/og7GiVtedjioAWS/UDrfHNVaJAEpG45lXh/y AKkXnj1KEMhwz/B2OTElMHRKP5WjQDRCdLNmacyrbB+9d+Dw8OtJ+p2CRY9X9mm5GVE2UarDTbJ OBpbH9vMKp2rgVX/snlLOERBhEIJRhSDCMzJIAVt64Qk+zT+uDmVFjnP0+Oag5kCbvX1PX+9cDC Qkrwq1oYcud3i34fam462Ds0eseoGfBc7qHrQO9FDPZ1o9zfCFnBhnv1ncSrBsChLc2KexCHQAb 1uTXBK/q2Ng6sdQkBv67CQs0jpveQDx0dj6hCzUcx7/00RP1kqeI8T2bXt9EtDTcsxhdGcFKiHK F0dS9LHTKni+73gDgIciRJxZIN1c3krCx7cwx8Pw== X-Google-Smtp-Source: AGHT+IEhg8XZRWBMSEKpku63c8O1q1ZZte16uMZdW/35liLEU8vQeK8GgJdwK6G0silDHSovmO93kw== X-Received: by 2002:a17:903:18c:b0:297:df8f:b056 with SMTP id d9443c01a7336-2986a6ba482mr241202595ad.11.1763522503541; Tue, 18 Nov 2025 19:21:43 -0800 (PST) Received: from pengdl-pc.mioffice.cn ([43.224.245.249]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2985c2bed5asm188352485ad.88.2025.11.18.19.21.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Nov 2025 19:21:42 -0800 (PST) From: Donglin Peng To: ast@kernel.org, andrii.nakryiko@gmail.com Cc: eddyz87@gmail.com, zhangxiaoqin@xiaomi.com, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Donglin Peng , Alan Maguire , Song Liu Subject: [RFC PATCH v7 1/7] libbpf: Add BTF permutation support for type reordering Date: Wed, 19 Nov 2025 11:15:25 +0800 Message-Id: <20251119031531.1817099-2-dolinux.peng@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251119031531.1817099-1-dolinux.peng@gmail.com> References: <20251119031531.1817099-1-dolinux.peng@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 | 166 +++++++++++++++++++++++++++++++++++++++ tools/lib/bpf/btf.h | 43 ++++++++++ tools/lib/bpf/libbpf.map | 1 + 3 files changed, 210 insertions(+) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 18907f0fcf9f..ab95ff19fde3 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -5829,3 +5829,169 @@ int btf__relocate(struct btf *btf, const struct btf= *base_btf) btf->owns_base =3D false; return libbpf_err(err); } + +struct btf_permute { + struct btf *btf; + __u32 *id_map; +}; + +/* Callback function to remap individual type ID references */ +static int btf_permute_remap_type_id(__u32 *type_id, void *ctx) +{ + struct btf_permute *p =3D ctx; + __u32 new_type_id =3D *type_id; + + /* skip references that point into the base BTF or VOID */ + if (new_type_id < p->btf->start_id) + return 0; + + /* invalid reference id */ + if (new_type_id >=3D btf__type_cnt(p->btf)) + return -EINVAL; + + new_type_id =3D p->id_map[new_type_id - p->btf->start_id]; + /* reference a dropped type is not allowed */ + if (new_type_id =3D=3D 0) + return -EINVAL; + + *type_id =3D 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 =3D NULL; + int err =3D 0, i, new_type_len; + __u32 *order_map =3D NULL; + __u32 id, new_nr_types =3D 0; + + if (!OPTS_VALID(opts, btf_permute_opts) || id_map_cnt !=3D btf->nr_types) + return libbpf_err(-EINVAL); + + /* used to record the storage sequence of types */ + order_map =3D calloc(btf->nr_types, sizeof(*id_map)); + if (!order_map) { + err =3D -ENOMEM; + goto done; + } + + new_types =3D calloc(btf->hdr->type_len, 1); + if (!new_types) { + err =3D -ENOMEM; + goto done; + } + + if (btf_ensure_modifiable(btf)) { + err =3D -ENOMEM; + goto done; + } + + for (i =3D 0; i < id_map_cnt; i++) { + id =3D id_map[i]; + /* Drop the specified type */ + if (id =3D=3D 0) + continue; + /* Invalid id */ + if (id < btf->start_id || id >=3D btf__type_cnt(btf)) { + err =3D -EINVAL; + goto done; + } + id -=3D btf->start_id; + /* Multiple types cannot be mapped to the same ID */ + if (order_map[id]) { + err =3D -EINVAL; + goto done; + } + order_map[id] =3D i + btf->start_id; + new_nr_types =3D max(id + 1, new_nr_types); + } + + /* Check for missing IDs */ + for (i =3D 0; i < new_nr_types; i++) { + if (order_map[i] =3D=3D 0) { + err =3D -EINVAL; + goto done; + } + } + + p.btf =3D btf; + p.id_map =3D id_map; + nt =3D new_types; + for (i =3D 0; i < new_nr_types; i++) { + struct btf_field_iter it; + const struct btf_type *t; + __u32 *type_id; + int type_size; + + id =3D order_map[i]; + /* must be a valid type ID */ + t =3D btf__type_by_id(btf, id); + if (!t) { + err =3D -EINVAL; + goto done; + } + type_size =3D btf_type_size(t); + memcpy(nt, t, type_size); + + /* Fix up referenced IDs for BTF */ + err =3D btf_field_iter_init(&it, nt, BTF_FIELD_ITER_IDS); + if (err) + goto done; + while ((type_id =3D btf_field_iter_next(&it))) { + err =3D btf_permute_remap_type_id(type_id, &p); + if (err) + goto done; + } + + nt +=3D type_size; + } + + /* Fix up referenced IDs for btf_ext */ + btf_ext =3D OPTS_GET(opts, btf_ext, NULL); + if (btf_ext) { + err =3D btf_ext_visit_type_ids(btf_ext, btf_permute_remap_type_id, &p); + if (err) + goto done; + } + + new_type_len =3D nt - new_types; + next_type =3D new_types; + end_type =3D next_type + new_type_len; + i =3D 0; + while (next_type + sizeof(struct btf_type) <=3D end_type) { + btf->type_offs[i++] =3D next_type - new_types; + next_type +=3D btf_type_size(next_type); + } + + /* Resize */ + if (new_type_len < btf->hdr->type_len) { + void *tmp_types; + + tmp_types =3D realloc(new_types, new_type_len); + if (new_type_len && !tmp_types) { + err =3D -ENOMEM; + goto done; + } + new_types =3D tmp_types; + btf->nr_types =3D new_nr_types; + btf->type_offs_cap =3D btf->nr_types; + btf->types_data_cap =3D new_type_len; + btf->hdr->type_len =3D new_type_len; + btf->hdr->str_off =3D new_type_len; + btf->raw_size =3D btf->hdr->hdr_len + btf->hdr->type_len + btf->hdr->str= _len; + } + + free(order_map); + free(btf->types_data); + btf->types_data =3D 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..e63dcce531b3 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 struc= t btf_dedup_opts *opts); */ LIBBPF_API int btf__relocate(struct btf *btf, const struct btf *base_btf); =20 +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 m= apping. + * 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 1 to `btf__type_cnt(btf)-1` + * - @id_map_cnt should be `btf__type_cnt(btf) - 1` + * - Mapping uses `id_map[original_id - 1] =3D 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_b= tf(btf))` + * - Mapping uses `id_map[original_id - btf__type_cnt(btf__base_btf(btf))]= =3D new_id` + * + * Setting @id_map element to 0 drops the corresponding type. Dropped type= s 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 **bt= f__dedup()** + * to clean up unreferenced strings. + * + * On error, returns negative error code and sets errno: + * - `-EINVAL`: Invalid parameters or ID mapping (duplicates, out-of-ran= ge) + * - `-ENOMEM`: Memory allocation failure + */ +LIBBPF_API int btf__permute(struct btf *btf, __u32 *id_map, __u32 id_map_c= nt, + const struct btf_permute_opts *opts); + struct btf_dump; =20 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; --=20 2.34.1