From patchwork Wed Mar 10 20:15:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ilya Leoshkevich X-Patchwork-Id: 12129309 X-Patchwork-Delegate: bpf@iogearbox.net 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 D6D72C433E0 for ; Wed, 10 Mar 2021 20:16:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6AB164FB3 for ; Wed, 10 Mar 2021 20:16:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231352AbhCJUQT (ORCPT ); Wed, 10 Mar 2021 15:16:19 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:9832 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231273AbhCJUQP (ORCPT ); Wed, 10 Mar 2021 15:16:15 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 12AK7Zhj104392; Wed, 10 Mar 2021 15:15:58 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=pp1; bh=z+9PSgltRJ9c+C44ZGtfGaY8sNCiVD6XcrBbcK9MouY=; b=p7XunCqyN16mgd5GK8tKM/y/qchGKKwvxan124bw8SvEqGGSPX7mtfAhK3uRRPUR0EO9 dRRfScatCDTJ54ssra1VQFrlG2Z9YyuNA6nzZzQLjishnx72BLqT3xoFTZJTqbYrba4/ tWhBLnJ8eQFIYDZdPOFHrAg9h8kZWweU5/rJqQkLWNG7UlCHTuCEbB5k5ETD7oieMKHh ZdAnTTz3Cz0tLp1UASOAaYwFbCWzAeHB16x7tVlYm//Ofr+8g8anq4O9b9Qx7oIKcaiw 1qSNz2fQ4FH7bFtmnHYFRbhte9wI6CmcE1IQG0wJrLQgkj4A5JWFkwIhYn4wkJ7SBvmi 8Q== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3774m50qrn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 10 Mar 2021 15:15:57 -0500 Received: from m0098417.ppops.net (m0098417.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 12AK7vDP109351; Wed, 10 Mar 2021 15:15:57 -0500 Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 3774m50qr5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 10 Mar 2021 15:15:57 -0500 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.0.43/8.16.0.43) with SMTP id 12AKFjUt029857; Wed, 10 Mar 2021 20:15:55 GMT Received: from b06avi18626390.portsmouth.uk.ibm.com (b06avi18626390.portsmouth.uk.ibm.com [9.149.26.192]) by ppma03ams.nl.ibm.com with ESMTP id 3768t4h9um-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 10 Mar 2021 20:15:55 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 12AKFbDs36176302 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 10 Mar 2021 20:15:37 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 713AAA4064; Wed, 10 Mar 2021 20:15:52 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E2DDDA405F; Wed, 10 Mar 2021 20:15:51 +0000 (GMT) Received: from vm.lan (unknown [9.145.31.74]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 10 Mar 2021 20:15:51 +0000 (GMT) From: Ilya Leoshkevich To: Arnaldo Carvalho de Melo , Andrii Nakryiko Cc: dwarves@vger.kernel.org, bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Yonghong Song , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v4 dwarves] btf: Add support for the floating-point types Date: Wed, 10 Mar 2021 21:15:50 +0100 Message-Id: <20210310201550.170599-1-iii@linux.ibm.com> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-03-10_10:2021-03-10,2021-03-10 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxlogscore=999 spamscore=0 adultscore=0 malwarescore=0 phishscore=0 clxscore=1015 impostorscore=0 mlxscore=0 bulkscore=0 suspectscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103100095 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Some BPF programs compiled on s390 fail to load, because s390 arch-specific linux headers contain float and double types. Fix as follows: - Make the DWARF loader fill base_type.float_type. - Introduce the --btf_gen_floats command-line parameter, so that pahole could be used to build both the older and the newer kernels. - libbpf introduced the support for the floating-point types in commit 986962fade5, so update the libbpf submodule to that version and use the new btf__add_float() function in order to emit the floating-point types when not in the compatibility mode. - Make the BTF loader recognize the new BTF kind. Example of the resulting entry in the vmlinux BTF: [7164] FLOAT 'double' size=8 when building with: LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} --btf_gen_floats Signed-off-by: Ilya Leoshkevich Acked-by: Andrii Nakryiko --- v1: https://lore.kernel.org/dwarves/20210306022203.152930-1-iii@linux.ibm.com/ v1 -> v2: Introduce libbpf compatibility level command-line parameter. The code should now work for both bpf-next/master and v5.12-rc2. v2: https://lore.kernel.org/dwarves/20210308235913.162038-1-iii@linux.ibm.com/ v2 -> v3: Use the feature flag (--encode_btf_kind_float) instead of the libbpf version flag. v3: https://lore.kernel.org/dwarves/20210310141517.169698-1-iii@linux.ibm.com/ v3 -> v4: Rename the flag to --btf_gen_floats. btf_loader.c | 21 +++++++++++++++++++-- dwarf_loader.c | 11 +++++++++++ lib/bpf | 2 +- libbtf.c | 36 ++++++++++++++++++++++++++++++++++-- libbtf.h | 1 + man-pages/pahole.1 | 5 +++++ pahole.c | 8 ++++++++ 7 files changed, 79 insertions(+), 5 deletions(-) diff --git a/btf_loader.c b/btf_loader.c index ec286f4..7cc39aa 100644 --- a/btf_loader.c +++ b/btf_loader.c @@ -160,7 +160,7 @@ static struct variable *variable__new(strings_t name, uint32_t linkage) return var; } -static int create_new_base_type(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) +static int create_new_int_type(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) { uint32_t attrs = btf_int_encoding(tp); strings_t name = tp->name_off; @@ -175,6 +175,20 @@ static int create_new_base_type(struct btf_elf *btfe, const struct btf_type *tp, return 0; } +static int create_new_float_type(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) +{ + strings_t name = tp->name_off; + struct base_type *base = base_type__new(name, 0, BT_FP_SINGLE, tp->size * 8); + + if (base == NULL) + return -ENOMEM; + + base->tag.tag = DW_TAG_base_type; + cu__add_tag_with_id(btfe->priv, &base->tag, id); + + return 0; +} + static int create_new_array(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) { struct btf_array *ap = btf_array(tp); @@ -397,7 +411,7 @@ static int btf_elf__load_types(struct btf_elf *btfe) switch (type) { case BTF_KIND_INT: - err = create_new_base_type(btfe, type_ptr, type_index); + err = create_new_int_type(btfe, type_ptr, type_index); break; case BTF_KIND_ARRAY: err = create_new_array(btfe, type_ptr, type_index); @@ -442,6 +456,9 @@ static int btf_elf__load_types(struct btf_elf *btfe) // BTF_KIND_FUNC corresponding to a defined subprogram. err = create_new_function(btfe, type_ptr, type_index); break; + case BTF_KIND_FLOAT: + err = create_new_float_type(btfe, type_ptr, type_index); + break; default: fprintf(stderr, "BTF: idx: %d, Unknown kind %d\n", type_index, type); fflush(stderr); diff --git a/dwarf_loader.c b/dwarf_loader.c index b73d786..c5e6681 100644 --- a/dwarf_loader.c +++ b/dwarf_loader.c @@ -461,6 +461,16 @@ static struct ptr_to_member_type *ptr_to_member_type__new(Dwarf_Die *die, return ptr; } +static uint8_t encoding_to_float_type(uint64_t encoding) +{ + switch (encoding) { + case DW_ATE_complex_float: return BT_FP_CMPLX; + case DW_ATE_float: return BT_FP_SINGLE; + case DW_ATE_imaginary_float: return BT_FP_IMGRY; + default: return 0; + } +} + static struct base_type *base_type__new(Dwarf_Die *die, struct cu *cu) { struct base_type *bt = tag__alloc(cu, sizeof(*bt)); @@ -474,6 +484,7 @@ static struct base_type *base_type__new(Dwarf_Die *die, struct cu *cu) bt->is_signed = encoding == DW_ATE_signed; bt->is_varargs = false; bt->name_has_encoding = true; + bt->float_type = encoding_to_float_type(encoding); } return bt; diff --git a/lib/bpf b/lib/bpf index 5af3d86..986962f 160000 --- a/lib/bpf +++ b/lib/bpf @@ -1 +1 @@ -Subproject commit 5af3d86b5a2c5fecdc3ab83822d083edd32b4396 +Subproject commit 986962fade5dfa89c2890f3854eb040d2a64ab38 diff --git a/libbtf.c b/libbtf.c index 9f76283..7ad7e9c 100644 --- a/libbtf.c +++ b/libbtf.c @@ -30,6 +30,7 @@ struct btf *base_btf; uint8_t btf_elf__verbose; uint8_t btf_elf__force; +bool btf_gen_floats = false; static int btf_var_secinfo_cmp(const void *a, const void *b) { @@ -227,6 +228,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = { [BTF_KIND_FUNC_PROTO] = "FUNC_PROTO", [BTF_KIND_VAR] = "VAR", [BTF_KIND_DATASEC] = "DATASEC", + [BTF_KIND_FLOAT] = "FLOAT", }; static const char *btf_elf__printable_name(const struct btf_elf *btfe, uint32_t offset) @@ -367,6 +369,27 @@ static void btf_log_func_param(const struct btf_elf *btfe, } } +static int32_t btf_elf__add_float_type(struct btf_elf *btfe, + const struct base_type *bt, + const char *name) +{ + int32_t id; + + id = btf__add_float(btfe->btf, name, BITS_ROUNDUP_BYTES(bt->bit_size)); + if (id < 0) { + btf_elf__log_err(btfe, BTF_KIND_FLOAT, name, true, "Error emitting BTF type"); + } else { + const struct btf_type *t; + + t = btf__type_by_id(btfe->btf, id); + btf_elf__log_type(btfe, t, false, true, + "size=%u nr_bits=%u", + t->size, bt->bit_size); + } + + return id; +} + int32_t btf_elf__add_base_type(struct btf_elf *btfe, const struct base_type *bt, const char *name) { @@ -379,8 +402,17 @@ int32_t btf_elf__add_base_type(struct btf_elf *btfe, const struct base_type *bt, encoding = BTF_INT_SIGNED; } else if (bt->is_bool) { encoding = BTF_INT_BOOL; - } else if (bt->float_type) { - fprintf(stderr, "float_type is not supported\n"); + } else if (bt->float_type && btf_gen_floats) { + /* + * Encode floats as BTF_KIND_FLOAT if allowed, otherwise (in + * compatibility mode) encode them as BTF_KIND_INT - that's not + * fully correct, but that's what it used to be. + */ + if (bt->float_type == BT_FP_SINGLE || + bt->float_type == BT_FP_DOUBLE || + bt->float_type == BT_FP_LDBL) + return btf_elf__add_float_type(btfe, bt, name); + fprintf(stderr, "Complex, interval and imaginary float types are not supported\n"); return -1; } diff --git a/libbtf.h b/libbtf.h index 191f586..c7cbe6e 100644 --- a/libbtf.h +++ b/libbtf.h @@ -35,6 +35,7 @@ extern struct btf *base_btf; extern uint8_t btf_elf__verbose; extern uint8_t btf_elf__force; #define btf_elf__verbose_log(fmt, ...) { if (btf_elf__verbose) printf(fmt, __VA_ARGS__); } +extern bool btf_gen_floats; #define PERCPU_SECTION ".data..percpu" diff --git a/man-pages/pahole.1 b/man-pages/pahole.1 index 352bb5e..e292b2c 100644 --- a/man-pages/pahole.1 +++ b/man-pages/pahole.1 @@ -199,6 +199,11 @@ Path to the base BTF file, for instance: vmlinux when encoding kernel module BTF This may be inferred when asking for a /sys/kernel/btf/MODULE, when it will be autoconfigured to "/sys/kernel/btf/vmlinux". +.TP +.B \-\-btf_gen_floats +Allow producing BTF_KIND_FLOAT entries in systems where the vmlinux DWARF +information has float types. + .TP .B \-l, \-\-show_first_biggest_size_base_type_member Show first biggest size base_type member. diff --git a/pahole.c b/pahole.c index 4a34ba5..c8d38f5 100644 --- a/pahole.c +++ b/pahole.c @@ -825,6 +825,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version; #define ARGP_just_packed_structs 319 #define ARGP_numeric_version 320 #define ARGP_btf_base 321 +#define ARGP_btf_gen_floats 322 static const struct argp_option pahole__options[] = { { @@ -1119,6 +1120,11 @@ static const struct argp_option pahole__options[] = { .key = ARGP_btf_encode_force, .doc = "Ignore those symbols found invalid when encoding BTF." }, + { + .name = "btf_gen_floats", + .key = ARGP_btf_gen_floats, + .doc = "Allow producing BTF_KIND_FLOAT entries." + }, { .name = "structs", .key = ARGP_just_structs, @@ -1254,6 +1260,8 @@ static error_t pahole__options_parser(int key, char *arg, base_btf_file = arg; break; case ARGP_numeric_version: print_numeric_version = true; break; + case ARGP_btf_gen_floats: + btf_gen_floats = true; break; default: return ARGP_ERR_UNKNOWN; }