From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AEA5C64ABE for ; Mon, 29 Jan 2024 13:05:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=205.220.165.32 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706533536; cv=fail; b=dq3UZka28mf5zNkD/NedPPFC2AZos7mmAhr+pTwLk241lxRiNmwIBAbHRp4fr6JHfi7EeWGy5iktO/nn2+PZ5lBDneqxc74utRkuGsCE95HrenThHCROWr+XeRQJNE8ErW6d+1YYd97r9HA4XMnUVYybGo1kJbg5lHcLt86MyRU= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706533536; c=relaxed/simple; bh=DYOW38kdKDeVojKQCGyQ8IIgxhe5eKvsNB5YM4ns9W4=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=IYxOFqBrl/I5Oz32bV6nTv05HvnptwMP6T4iBRo2Cog7UxLZXDPFWLqPppM2e4T2ZmIDxGCuGoRRsGS9W2kmSD8soxUfkCV0dg71+2950U/0+IFvJCgH9cz20zxv1RLtnY1rA36TaRgZfbGibU9XYxnI3TdnQpcjXkSM2ueixXY= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=l6TzgI9n; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b=JmuqnuOw; arc=fail smtp.client-ip=205.220.165.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="l6TzgI9n"; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b="JmuqnuOw" Received: from pps.filterd (m0333521.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 40T9iYPl021913; Mon, 29 Jan 2024 13:05:13 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=message-id : date : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding : mime-version; s=corp-2023-11-20; bh=8ElH8PXztppYF38YMGTfCbf+GAe9ECqGf+KA2K1Kf4M=; b=l6TzgI9n/gY2nYESDF8jfGvoFDYCkTb+Znc0nng8Jggs5UKhcCBgv4ZScuaLl8u20GK4 14yDIsWnddIGNuNYchyuH9kAmoTGjaAvVUP5KF2h4ga/gqcX7cbZ0NbBEbHKEl8STL6s o+HLhoEKA2PsT8oq70vLzPsAoPXUkXcN15DM7T11zVhQjwTScYO+4LFEmQjMrGbnQHaJ xTjq0LgyDnM8+6GxNzz/D6VsTnYLcxjZ7SGr7DUL+vEcufuMje/LZjk26sy2FSkXlk1U bk1yAbCwVb2AMbxwF1vNxNo7vB3cz56kAoOQhQrOngqoblhVTGcXccVd/94ZRhTLyZiA Qg== Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.appoci.oracle.com [130.35.103.27]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3vvrrcbu3q-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 29 Jan 2024 13:05:13 +0000 Received: from pps.filterd (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 40TCiAI2008488; Mon, 29 Jan 2024 13:05:12 GMT Received: from nam02-bn1-obe.outbound.protection.outlook.com (mail-bn1nam02lp2040.outbound.protection.outlook.com [104.47.51.40]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 3vvr9c3gt9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 29 Jan 2024 13:05:12 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=FpC1lq2X8fOuttzN0lIcS8+8qEA8BoN2DNrjc/0mU0Kg7Y3fDdYHqbVbx+kHS24ubdiMNahOr3PA3ydk6RmCo/ZY15A97X6QosZ7o4GC3suYsXp5ixdWbO/ibWgDURUn7Hae13oz3550B4cOdXsa+5IgmwRNmUjrXAPdIm6TcihD5rtPJuC0tYVHoZF9jcsmYL57M7L/bPh8tHrl/XalfplrxEOeHNmaPVxt40pNZutOYQkktKXcvZ2gsE7zLOp8KZPo0CXKNUGJvfiu5lYRn6wM5z2q+LIqzm189pjcs19xvUGLBEI6G9cQuJEREl0p0QpqVJNI4qFfZ8l0IwDCnA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=8ElH8PXztppYF38YMGTfCbf+GAe9ECqGf+KA2K1Kf4M=; b=en0GtALrF38z9nE3EkHbwXpwqjxl+D/sKSKRqvAjgN3x/QtU9Jl1zwy95Yvhn+tZT9W6bm/oGvtw5rvViITdoQ470+aQkMd54ciA0MYoAoxjTi4iDT7yvN9aUtVxZJnG7o83xlf4aKCJQ/UpRsgwQce0IiR2s5zFpDEuAFHX7MH1ftFT/qfzKQZDOjJrHcimSIDdbvYDAlwBdv6sEH4jjBADuH1/4CRXMhBzaCqbOAhHqZBkqbCgTA8PM0+vwxfi8SGy/vv+yDG00Ob2XFMeZtyHZ839Dy4lTiorq82pGPjWYPYVySmjrGZR4+qrtneRDj9tZsPwyE6oL6OsCOArfQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=8ElH8PXztppYF38YMGTfCbf+GAe9ECqGf+KA2K1Kf4M=; b=JmuqnuOwXYx+Ke5FF5bpCej5aWTh4sOVRCCrBOX/tfO+WienrKswVznczkG8eJ35QC65UeasYf0Z3p8xIY5J/7VWnZvQz1KEdyK0MDCvOksnMtkKfvXKhkwv9+spmOh6kHu5PUJ1Yg4dNplY9wuVdE9I/gbdIwcD+dt9AJAQLZE= Received: from BLAPR10MB5267.namprd10.prod.outlook.com (2603:10b6:208:30e::22) by CH3PR10MB6689.namprd10.prod.outlook.com (2603:10b6:610:153::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7228.34; Mon, 29 Jan 2024 13:05:09 +0000 Received: from BLAPR10MB5267.namprd10.prod.outlook.com ([fe80::b3b:c19f:bbba:7f70]) by BLAPR10MB5267.namprd10.prod.outlook.com ([fe80::b3b:c19f:bbba:7f70%7]) with mapi id 15.20.7228.029; Mon, 29 Jan 2024 13:05:09 +0000 Message-ID: <49da8aff-1ec7-b908-2167-ee499e7a857a@oracle.com> Date: Mon, 29 Jan 2024 13:05:05 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 Subject: Re: [PATCH dwarves v3] pahole: Inject kfunc decl tags into BTF To: Daniel Xu , acme@kernel.org, jolsa@kernel.org, quentin@isovalent.com Cc: andrii.nakryiko@gmail.com, ast@kernel.org, daniel@iogearbox.net, bpf@vger.kernel.org References: <0f25134ec999e368478c4ca993b3b729c2a03383.1706491733.git.dxu@dxuuu.xyz> Content-Language: en-GB From: Alan Maguire In-Reply-To: <0f25134ec999e368478c4ca993b3b729c2a03383.1706491733.git.dxu@dxuuu.xyz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: LO4P123CA0165.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:18a::8) To BLAPR10MB5267.namprd10.prod.outlook.com (2603:10b6:208:30e::22) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BLAPR10MB5267:EE_|CH3PR10MB6689:EE_ X-MS-Office365-Filtering-Correlation-Id: 5ffa3eae-80bd-4349-9dfb-08dc20caec1d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BLAPR10MB5267.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(39860400002)(396003)(366004)(346002)(136003)(376002)(230922051799003)(451199024)(1800799012)(186009)(64100799003)(316002)(66476007)(66946007)(66556008)(8936002)(8676002)(4326008)(83380400001)(31686004)(478600001)(6666004)(31696002)(38100700002)(6486002)(86362001)(30864003)(2906002)(5660300002)(44832011)(6512007)(6506007)(2616005)(53546011)(36756003)(41300700001)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UHdjdHBvd3BYcmdiNitMVWVOaGVCY1htSnpla1ZRak5ONDRJcFozWi9zdzhZ?= =?utf-8?B?Q2xlOHArRlQ3UTJUREJ5SE1ISUNhY2NHbElCUWFWOVkxYzNhOTFDdHIxOEwz?= =?utf-8?B?V1VZQjBHRGFUUy9OaG1CSEtmSlRpZlE1TnpvVFNkcFZzb2lLdHlGMU5PZ1R2?= =?utf-8?B?d2cvd2VXbkh4bzdrRFBWRWs4c3AyVGZ2aEdSL2NmOUhZYytBOEdLL0xLVTRp?= =?utf-8?B?TDZHM2tjazU2eitGckhkbU5DQmx5UXh0NlBYUzhScFV6VldXdHlKOGlrc2JO?= =?utf-8?B?bXJWcm9ZbzVBNmxXcDhLZmxoRTEvekhpN0prZk9hb2pIUmMzTFVlL2FVKzZJ?= =?utf-8?B?V1hOcHczeGFiOXAxaXE5bmJXZm9TbjFabFlSM01uUkhaTjNGMTYvek4xUFFo?= =?utf-8?B?TFM4M1d0OUJydzZULzVjaEhZVXlvNUx6WG5KOSswUVlWaHpaWHhLUHlHcHJ1?= =?utf-8?B?TzNNUVZXYnBqLzdBYWZYZGkzclArcy9GMTRFbGovS1Z5SHZqbVdYSHhpVTJr?= =?utf-8?B?YTUyOFVlRmVVL2ppZXp0N3lYeGpTVHQrSGxnNW8vNG5Zc1QzZyt1bG96cFV1?= =?utf-8?B?K3g3Z1UyVVpESUFEQzVlOUdKUkJpbXZFSDNMd0JTWU1vMnFDaUhiUm5rKys5?= =?utf-8?B?OWV3L0NEU2tsVURlWmthNmR2alNSNlkrd2xoZGlHSDhFRkZYQy8yTE9TNEQv?= =?utf-8?B?THhQNU1OVzdTbmZKbVpmelFRRENjV0srNXdDR1M2NDZqbjRBQ3Z2SERYaWov?= =?utf-8?B?Mi9HTCtSNzFETEdjd1BqejJYSTNWMjRDeW5TN3lDOVNBTUVXMGJlSkxkdWlI?= =?utf-8?B?dWVleFQ2Zk4vWmw1TUZYeWJtdUcyWFRpVENFRkdiV1VYOWl3QjJ6SGtXN0lp?= =?utf-8?B?a0FyYUtEaEEvdEpwYWplUVltTUtEcGxtVUdOTktNY2xnWkZZSkxpdkNUSlky?= =?utf-8?B?dXk4c3R1aGgrVzhrNFZjeWEvbkQrdnM3dGJHN0pFbHV3cDl2dEM5M2ttdmFz?= =?utf-8?B?Tk51QUxXRE1FNXNFdTFFemVaRUd3Rm5TK2F6S0trQ1FYQXNOSTRnK3FSVmRI?= =?utf-8?B?WW16SmZUTnRKMjNGVExEdzVBT0s1b0Y3Q3AxOU85OVBiVVhjN2xDb2hKWU5P?= =?utf-8?B?cmlpTVdKN3pPL0ZDU0plU2x5M3VZeW9Ic2Zwb2U1aENqbG9QMW5tZlEzREpR?= =?utf-8?B?SEQrc2pCbFkwZUJsbElSSjdhY3hOMGJ0UUtpWFFjNG9iWndGUC9OSEtRMTl3?= =?utf-8?B?TkpLVHBaNDlNTk8zbjRzcm8rSlRMQThyZ2FDSDhjOVRnY2drNThpWFppOGVq?= =?utf-8?B?VTRsa1F2MnQ1SXgyek00Z3JWUnhtd252V0VEN09KLzVPTTMvczVmSHZ5V3RX?= =?utf-8?B?YkFPTjhPQ2FEZHJmNUY1bml1eXJnTEoxdFlHRjZOQUgyQ3dsbm9HRVhpRlNn?= =?utf-8?B?d0dXaGVSNXFaVGhPejI4d0piMWhxMm5ZNTZremdVVjA1U0IzOHFXZDRuVGtH?= =?utf-8?B?MHpuckpiby9CdWhvNkJuTmM3aC9DRndTU0JPZjNYUmdMdnFYYk9KUkhMdmFX?= =?utf-8?B?aHM3K3BvZVR5a0xEK1Y3WHRTYnExcWVRY0JNeFM2VHdlYzgxMER4N2pHWWs3?= =?utf-8?B?TElVMTdlN1MvMUNPNWU0OEVZR0V5ajJqZU95V1poRVJaalBabEowMHdkTG9O?= =?utf-8?B?dDlHSmc2dGJxYjhZM2ZYVVhLUERCOTZFQmIvbWdWc2VsTG9BS2xLWHR1aldT?= =?utf-8?B?ZHZrakRORzZGcE5KM2t2TXBodmZESmdDbUxKVnRyQXVLelp5NWp1d3p1VnhZ?= =?utf-8?B?N2QxQzJrMytBZWRmQndhK1NxbGJVLytILzJvNHpKTi9URTZzYmErai9lWUhN?= =?utf-8?B?WUExbVR0R1NhOFR2ajVIaHBsWUdHTFJDb3g1QXdFYWwwWmlPclhGcTJWTTl4?= =?utf-8?B?cm1naXFDVEVoalRQbHg1bmZJc1puR1FISTlxR0pOTHVGa2NsWC84dWxqRE1x?= =?utf-8?B?cXRJemtYdmVaUXNMUkJmMHExSkYvRFpzWmhnTktLZXgzUnFpYjh1NjRyUnFw?= =?utf-8?B?elBxZTRiTjNnNEdzczVYeVhGL2xWZGR3SGpWd2dweWhNWW01YTBIMllKNTlk?= =?utf-8?B?VUhFQ1ZWZXl2Y0gzRGMrbWlkbE5NdmFpZ0d5YnVTSTA2dld4V0tnbks4b3Ba?= =?utf-8?Q?WXAN+lleogbz0wnfOjBFLFc=3D?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5ffa3eae-80bd-4349-9dfb-08dc20caec1d X-MS-Exchange-CrossTenant-AuthSource: BLAPR10MB5267.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jan 2024 13:05:09.7687 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: OOPjLgR1rDybeDXgSKLgwtSDhSnmdCWFsBxNZSc/4m7cMDfRryryjlbasKsLja07nQPZtY8vP60kPepWfp/fTA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR10MB6689 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-01-29_07,2024-01-29_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 phishscore=0 malwarescore=0 spamscore=0 mlxlogscore=999 adultscore=0 bulkscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2401290095 X-Proofpoint-ORIG-GUID: nTh0OxrcaixjkO-nKMLpJiiYJxh0oTTs X-Proofpoint-GUID: nTh0OxrcaixjkO-nKMLpJiiYJxh0oTTs On 29/01/2024 01:30, Daniel Xu wrote: > This commit teaches pahole to parse symbols in .BTF_ids section in > vmlinux and discover exported kfuncs. Pahole then takes the list of > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > Example of encoding: > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > 121 > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > This enables downstream users and tools to dynamically discover which > kfuncs are available on a system by parsing vmlinux or module BTF, both > available in /sys/kernel/btf. > > Signed-off-by: Daniel Xu > This should probably be a BTF feature supported by --btf_features; that way we'd have a mechanism to switch it off if needed. Can you look at adding a "tag_kfunc" or whatever name suits into the btf_features[] array in pahole.c? Something like: BTF_FEATURE(tag_kfunc, btf_tag_kfunc, false), You'll also then need to add a btf_tag_kfunc boolean field to struct conf_load, and generation of kfunc tags should then be guarded by if (conf_load->btf_tag_kfunc) ...so that the tags are added conditionally depending on whether the user wants them. Then if a user specifies --btf_features=all or some subset of BTF features including "tag_kfunc" they will get kfunc tags. We probably should also move to using --btf_features instead of the current combination of "--" parameters when pahole is bumped to v1.26. > --- > Changes from v2: > * More reliably detect kfunc membership in set8 by tracking set addr ranges > * Rename some variables/functions to be more clear about kfunc vs func > > Changes from v1: > * Fix resource leaks > * Fix callee -> caller typo > * Rename btf_decl_tag from kfunc -> bpf_kfunc > * Only grab btf_id_set funcs tagged kfunc > * Presort btf func list > > btf_encoder.c | 347 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 347 insertions(+)rre > > diff --git a/btf_encoder.c b/btf_encoder.c > index fd04008..4f742b1 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -34,6 +34,11 @@ > #include > > #define BTF_ENCODER_MAX_PROTO 512 > +#define BTF_IDS_SECTION ".BTF_ids" > +#define BTF_ID_FUNC_PFX "__BTF_ID__func__" > +#define BTF_ID_SET8_PFX "__BTF_ID__set8__" > +#define BTF_SET8_KFUNCS (1 << 0) > +#define BTF_KFUNC_TYPE_TAG "bpf_kfunc" > > /* state used to do later encoding of saved functions */ > struct btf_encoder_state { > @@ -79,6 +84,7 @@ struct btf_encoder { > gen_floats, > is_rel; > uint32_t array_index_id; > + struct gobuffer btf_funcs; > struct { > struct var_info vars[MAX_PERCPU_VAR_CNT]; > int var_cnt; > @@ -94,6 +100,17 @@ struct btf_encoder { > } functions; > }; > > +struct btf_func { > + const char *name; > + int type_id; > +}; > + > +/* Half open interval representing range of addresses containing kfuncs */ > +struct btf_kfunc_set_range { > + size_t start; > + size_t end; > +}; > + > static LIST_HEAD(encoders); > static pthread_mutex_t encoders__lock = PTHREAD_MUTEX_INITIALIZER; > > @@ -1352,6 +1369,327 @@ out: > return err; > } > > +/* Returns if `sym` points to a kfunc set */ > +static int is_sym_kfunc_set(GElf_Sym *sym, const char *name, Elf_Data *idlist, size_t idlist_addr) > +{ > + int *ptr = idlist->d_buf; > + int idx, flags; > + bool is_set8; > + > + /* kfuncs are only found in BTF_SET8's */ > + is_set8 = !strncmp(name, BTF_ID_SET8_PFX, sizeof(BTF_ID_SET8_PFX) - 1); > + if (!is_set8) > + return false; > + > + idx = sym->st_value - idlist_addr; > + if (idx >= idlist->d_size) { > + fprintf(stderr, "%s: symbol '%s' out of bounds\n", __func__, name); > + return false; > + } > + > + /* Check the set8 flags to see if it was marked as kfunc */ > + idx = idx / sizeof(int); > + flags = ptr[idx + 1]; > + return flags & BTF_SET8_KFUNCS; > +} > + > +/* > + * Parse BTF_ID symbol and return the func name. > + * > + * Returns: > + * Caller-owned string containing func name if successful. > + * NULL if !func or on error. > + */ > +static char *get_func_name(const char *sym) > +{ > + char *func, *end; > + > + if (strncmp(sym, BTF_ID_FUNC_PFX, sizeof(BTF_ID_FUNC_PFX) - 1)) > + return NULL; > + > + /* Strip prefix */ > + func = strdup(sym + sizeof(BTF_ID_FUNC_PFX) - 1); > + > + /* Strip suffix */ > + end = strrchr(func, '_'); > + if (!end || *(end - 1) != '_') { > + free(func); > + return NULL; > + } > + *(end - 1) = '\0'; > + > + return func; > +} > + > +static int btf_func_cmp(const void *_a, const void *_b) > +{ > + const struct btf_func *a = _a; > + const struct btf_func *b = _b; > + > + return strcmp(a->name, b->name); > +} > + > +/* > + * Collects all functions described in BTF. > + * Returns non-zero on error. > + */ > +static int btf_encoder__collect_btf_funcs(struct btf_encoder *encoder) > +{ > + struct gobuffer *funcs = &encoder->btf_funcs; > + struct btf *btf = encoder->btf; > + int nr_types, type_id; > + int err = -1; > + > + /* First collect all the func entries into an array */ > + nr_types = btf__type_cnt(btf); > + for (type_id = 1; type_id < nr_types; type_id++) { > + const struct btf_type *type; > + struct btf_func func = {}; > + const char *name; > + > + type = btf__type_by_id(btf, type_id); > + if (!type) { > + fprintf(stderr, "%s: malformed BTF, can't resolve type for ID %d\n", > + __func__, type_id); > + err = -EINVAL; > + goto out; > + } > + > + if (!btf_is_func(type)) > + continue; > + > + name = btf__name_by_offset(btf, type->name_off); > + if (!name) { > + fprintf(stderr, "%s: malformed BTF, can't resolve name for ID %d\n", > + __func__, type_id); > + err = -EINVAL; > + goto out; > + } > + > + func.name = name; > + func.type_id = type_id; > + err = gobuffer__add(funcs, &func, sizeof(func)); > + if (err < 0) > + goto out; > + } > + > + /* Now that we've collected funcs, sort them by name */ > + qsort((void *)gobuffer__entries(funcs), gobuffer__nr_entries(funcs), > + sizeof(struct btf_func), btf_func_cmp); > + > + err = 0; > +out: > + return err; > +} > + > +static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, const char *kfunc) > +{ > + struct btf_func key = { .name = kfunc }; > + struct btf *btf = encoder->btf; > + struct btf_func *target; > + const void *base; > + unsigned int cnt; > + int err = -1; > + > + base = gobuffer__entries(&encoder->btf_funcs); > + cnt = gobuffer__nr_entries(&encoder->btf_funcs); > + target = bsearch(&key, base, cnt, sizeof(key), btf_func_cmp); > + if (!target) { > + fprintf(stderr, "%s: failed to find kfunc '%s' in BTF\n", __func__, kfunc); > + goto out; > + } > + > + /* Note we are unconditionally adding the btf_decl_tag even > + * though vmlinux may already contain btf_decl_tags for kfuncs. > + * We are ok to do this b/c we will later btf__dedup() to remove > + * any duplicates. > + */ > + err = btf__add_decl_tag(btf, BTF_KFUNC_TYPE_TAG, target->type_id, -1); > + if (err < 0) { > + fprintf(stderr, "%s: failed to insert kfunc decl tag for '%s': %d\n", > + __func__, kfunc, err); > + goto out; > + } > + > + err = 0; > +out: > + return err; > +} > + > +static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder) > +{ > + const char *filename = encoder->filename; > + struct gobuffer btf_kfunc_ranges = {}; > + Elf_Scn *symscn = NULL; > + int symbols_shndx = -1; > + int fd = -1, err = -1; > + int idlist_shndx = -1; > + Elf_Scn *scn = NULL; > + size_t idlist_addr; > + Elf_Data *symbols; > + Elf_Data *idlist; > + size_t strtabidx; > + Elf *elf = NULL; > + GElf_Shdr shdr; > + size_t strndx; > + char *secname; > + int nr_syms; > + int i = 0; > + > + fd = open(filename, O_RDONLY); > + if (fd < 0) { > + fprintf(stderr, "Cannot open %s\n", filename); > + goto out; > + } > + > + if (elf_version(EV_CURRENT) == EV_NONE) { > + elf_error("Cannot set libelf version"); > + goto out; > + } > + > + elf = elf_begin(fd, ELF_C_READ, NULL); > + if (elf == NULL) { > + elf_error("Cannot update ELF file"); > + goto out; > + } > + > + /* Location symbol table and .BTF_ids sections */ > + elf_getshdrstrndx(elf, &strndx); > + while ((scn = elf_nextscn(elf, scn)) != NULL) { > + Elf_Data *data; > + > + i++; > + if (!gelf_getshdr(scn, &shdr)) { > + elf_error("Failed to get ELF section(%d) hdr", i); > + goto out; > + } > + > + secname = elf_strptr(elf, strndx, shdr.sh_name); > + if (!secname) { > + elf_error("Failed to get ELF section(%d) hdr name", i); > + goto out; > + } > + > + data = elf_getdata(scn, 0); > + if (!data) { > + elf_error("Failed to get ELF section(%d) data", i); > + goto out; > + } > + > + if (shdr.sh_type == SHT_SYMTAB) { > + symbols_shndx = i; > + symscn = scn; > + symbols = data; > + strtabidx = shdr.sh_link; > + } else if (!strcmp(secname, BTF_IDS_SECTION)) { > + idlist_shndx = i; > + idlist_addr = shdr.sh_addr; > + idlist = data; > + } > + } > + > + /* Cannot resolve symbol or .BTF_ids sections. Nothing to do. */ > + if (symbols_shndx == -1 || idlist_shndx == -1) { > + err = 0; > + goto out; > + } > + > + if (!gelf_getshdr(symscn, &shdr)) { > + elf_error("Failed to get ELF symbol table header"); > + goto out; > + } > + nr_syms = shdr.sh_size / shdr.sh_entsize; > + > + err = btf_encoder__collect_btf_funcs(encoder); > + if (err) { > + fprintf(stderr, "%s: failed to collect BTF funcs\n", __func__); > + goto out; > + } > + > + /* First collect all kfunc set ranges. > + * > + * Note we choose not to sort these ranges and accept a linear > + * search when doing lookups. Reasoning is that the number of > + * sets is ~O(100) and not worth the additional code to optimize. > + */ > + for (i = 0; i < nr_syms; i++) { > + struct btf_kfunc_set_range range = {}; > + const char *name; > + GElf_Sym sym; > + > + if (!gelf_getsym(symbols, i, &sym)) { > + elf_error("Failed to get ELF symbol(%d)", i); > + goto out; > + } > + > + if (sym.st_shndx != idlist_shndx) > + continue; > + > + name = elf_strptr(elf, strtabidx, sym.st_name); > + if (!is_sym_kfunc_set(&sym, name, idlist, idlist_addr)) > + continue; > + > + range.start = sym.st_value; > + range.end = sym.st_value + sym.st_size; > + gobuffer__add(&btf_kfunc_ranges, &range, sizeof(range)); > + } > + > + /* Now inject BTF with kfunc decl tag for detected kfuncs */ > + for (i = 0; i < nr_syms; i++) { > + const struct btf_kfunc_set_range *ranges; > + unsigned int ranges_cnt; > + char *func, *name; > + GElf_Sym sym; > + bool found; > + int err; > + int j; > + > + if (!gelf_getsym(symbols, i, &sym)) { > + elf_error("Failed to get ELF symbol(%d)", i); > + goto out; > + } > + > + if (sym.st_shndx != idlist_shndx) > + continue; > + > + name = elf_strptr(elf, strtabidx, sym.st_name); > + func = get_func_name(name); > + if (!func) > + continue; > + > + /* Check if function belongs to a kfunc set */ > + ranges = gobuffer__entries(&btf_kfunc_ranges); > + ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges); > + found = false; > + for (j = 0; j < ranges_cnt; j++) { > + size_t addr = sym.st_value; > + if (ranges[j].start <= addr && addr < ranges[j].end) { > + found = true; > + break; > + } > + } > + if (!found) > + continue; > + > + err = btf_encoder__tag_kfunc(encoder, func); > + if (err) { > + fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func); > + free(func); > + goto out; > + } > + free(func); > + } > + > + err = 0; > +out: > + __gobuffer__delete(&btf_kfunc_ranges); > + if (elf) > + elf_end(elf); > + if (fd != -1) > + close(fd); > + return err; > +} > + > int btf_encoder__encode(struct btf_encoder *encoder) > { > int err; > @@ -1366,6 +1704,14 @@ int btf_encoder__encode(struct btf_encoder *encoder) > if (btf__type_cnt(encoder->btf) == 1) > return 0; > > + /* Note vmlinux may already contain btf_decl_tag's for kfuncs. So > + * take care to call this before btf_dedup(). > + */ > + if (btf_encoder__tag_kfuncs(encoder)) { > + fprintf(stderr, "%s: failed to tag kfuncs!\n", __func__); > + return -1; > + } > + > if (btf__dedup(encoder->btf, NULL)) { > fprintf(stderr, "%s: btf__dedup failed!\n", __func__); > return -1; > @@ -1712,6 +2058,7 @@ void btf_encoder__delete(struct btf_encoder *encoder) > > btf_encoders__delete(encoder); > __gobuffer__delete(&encoder->percpu_secinfo); > + __gobuffer__delete(&encoder->btf_funcs); > zfree(&encoder->filename); > btf__free(encoder->btf); > encoder->btf = NULL;