From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30451C433DB for ; Sun, 7 Feb 2021 07:18:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFD5364E2C for ; Sun, 7 Feb 2021 07:18:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229506AbhBGHSQ (ORCPT ); Sun, 7 Feb 2021 02:18:16 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:18656 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229561AbhBGHSP (ORCPT ); Sun, 7 Feb 2021 02:18:15 -0500 Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 1177EChS015678 for ; Sat, 6 Feb 2021 23:17:34 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=5PC7WYr1QotyXssiolMqSmbktTZof/unhpuMu7UmYg8=; b=Horn5KpBJGE9vi7+/eTpDowUsfEvkktC8lIcBLOXqdf+RY0OpHoJXK/O5JY424q6kPaw ftM8pF4Q9rcdLlwXV2PJc7xR+rm2BInbn+fbJVDLwcFdIv2R5+ANWmxN6oTjyAW9vn3q SynEytotsmelujVvOrQhtfCEBv/rPvK/zLQ= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 36hsgtapp3-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sat, 06 Feb 2021 23:17:34 -0800 Received: from intmgw002.25.frc3.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:11d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Sat, 6 Feb 2021 23:17:32 -0800 Received: by devbig003.ftw2.facebook.com (Postfix, from userid 128203) id 049413705541; Sat, 6 Feb 2021 23:17:26 -0800 (PST) From: Yonghong Song To: , CC: , , , , , Andrii Nakryiko Subject: [PATCH dwarves v2] btf_encoder: sanitize non-regular int base type Date: Sat, 6 Feb 2021 23:17:26 -0800 Message-ID: <20210207071726.3969978-1-yhs@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.737 definitions=2021-02-07_03:2021-02-05,2021-02-07 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 mlxlogscore=968 spamscore=0 mlxscore=0 clxscore=1015 adultscore=0 bulkscore=0 phishscore=0 suspectscore=0 lowpriorityscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102070052 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org clang with dwarf5 may generate non-regular int base type, i.e., not a signed/unsigned char/short/int/longlong/__int128. Such base types are often used to describe how an actual parameter or variable is generated. For example, 0x000015cf: DW_TAG_base_type DW_AT_name ("DW_ATE_unsigned_1") DW_AT_encoding (DW_ATE_unsigned) DW_AT_byte_size (0x00) 0x00010ed9: DW_TAG_formal_parameter DW_AT_location (DW_OP_lit0, DW_OP_not, DW_OP_convert (0x000015cf) "DW_A= TE_unsigned_1", DW_OP_convert (0x000015d4) "DW_A= TE_unsigned_8", DW_OP_stack_value) DW_AT_abstract_origin (0x00013984 "branch") What it does is with a literal "0", did a "not" operation, and the conver= ted to one-bit unsigned int and then 8-bit unsigned int. Another example, 0x000e97e4: DW_TAG_base_type DW_AT_name ("DW_ATE_unsigned_24") DW_AT_encoding (DW_ATE_unsigned) DW_AT_byte_size (0x03) 0x000f88f8: DW_TAG_variable DW_AT_location (indexed (0x3c) loclist =3D 0x000= 08fb0: [0xffffffff82808812, 0xffffffff82808817): DW_OP_breg0 RAX+0, DW_OP_convert (0x000e97d5) "DW_ATE_unsigned_64", DW_OP_convert (0x000e97df) "DW_ATE_unsigned_8", DW_OP_stack_value, DW_OP_piece 0x1, DW_OP_breg0 RAX+0, DW_OP_convert (0x000e97d5) "DW_ATE_unsigned_64", DW_OP_convert (0x000e97da) "DW_ATE_unsigned_32", DW_OP_lit8, DW_OP_shr, DW_OP_convert (0x000e97da) "DW_ATE_unsigned_32", DW_OP_convert (0x000e97e4) "DW_ATE_unsigned_24", DW_OP_stack_value, DW_OP_piece 0x3 ...... At one point, a right shift by 8 happens and the result is converted to 32-bit unsigned int and then to 24-bit unsigned int. BTF does not need any of these DW_OP_* information and such non-regular i= nt types will cause libbpf to emit errors. Let us sanitize them to generate BTF acceptable to libbpf and kernel. Cc: Sedat Dilek Acked-by: Andrii Nakryiko Signed-off-by: Yonghong Song --- libbtf.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/libbtf.c b/libbtf.c index 9f76283..5843200 100644 --- a/libbtf.c +++ b/libbtf.c @@ -373,6 +373,7 @@ int32_t btf_elf__add_base_type(struct btf_elf *btfe, = const struct base_type *bt, struct btf *btf =3D btfe->btf; const struct btf_type *t; uint8_t encoding =3D 0; + uint16_t byte_sz; int32_t id; =20 if (bt->is_signed) { @@ -384,7 +385,43 @@ int32_t btf_elf__add_base_type(struct btf_elf *btfe,= const struct base_type *bt, return -1; } =20 - id =3D btf__add_int(btf, name, BITS_ROUNDUP_BYTES(bt->bit_size), encodi= ng); + /* dwarf5 may emit DW_ATE_[un]signed_{num} base types where + * {num} is not power of 2 and may exceed 128. Such attributes + * are mostly used to record operation for an actual parameter + * or variable. + * For example, + * DW_AT_location (indexed (0x3c) loclist =3D 0x00008fb0: + * [0xffffffff82808812, 0xffffffff82808817): + * DW_OP_breg0 RAX+0, + * DW_OP_convert (0x000e97d5) "DW_ATE_unsigned_64", + * DW_OP_convert (0x000e97df) "DW_ATE_unsigned_8", + * DW_OP_stack_value, + * DW_OP_piece 0x1, + * DW_OP_breg0 RAX+0, + * DW_OP_convert (0x000e97d5) "DW_ATE_unsigned_64", + * DW_OP_convert (0x000e97da) "DW_ATE_unsigned_32", + * DW_OP_lit8, + * DW_OP_shr, + * DW_OP_convert (0x000e97da) "DW_ATE_unsigned_32", + * DW_OP_convert (0x000e97e4) "DW_ATE_unsigned_24", + * DW_OP_stack_value, DW_OP_piece 0x3 + * DW_AT_name ("ebx") + * DW_AT_decl_file ("/linux/arch/x86/events/intel/core.c") + * + * In the above example, at some point, one unsigned_32 value + * is right shifted by 8 and the result is converted to unsigned_32 + * and then unsigned_24. + * + * BTF does not need such DW_OP_* information so let us sanitize + * these non-regular int types to avoid libbpf/kernel complaints. + */ + byte_sz =3D BITS_ROUNDUP_BYTES(bt->bit_size); + if (!byte_sz || (byte_sz & (byte_sz - 1))) { + name =3D "__SANITIZED_FAKE_INT__"; + byte_sz =3D 4; + } + + id =3D btf__add_int(btf, name, byte_sz, encoding); if (id < 0) { btf_elf__log_err(btfe, BTF_KIND_INT, name, true, "Error emitting BTF t= ype"); } else { --=20 2.24.1