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Marchesi" To: Andrii Nakryiko Cc: James Hilliard , bpf , david.faust@oracle.com Subject: Re: bpftool gen object doesn't handle GCC built BPF ELF files References: Date: Fri, 08 Jul 2022 16:51:58 +0200 In-Reply-To: (Andrii Nakryiko's message of "Wed, 6 Jul 2022 10:20:47 -0700") Message-ID: <87wncnd5dd.fsf@oracle.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Content-Type: text/plain X-ClientProxiedBy: LO4P123CA0237.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:1a7::8) To BYAPR10MB2888.namprd10.prod.outlook.com (2603:10b6:a03:88::32) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 7baea5ae-5c39-4a11-aa0e-08da60f16d20 X-MS-TrafficTypeDiagnostic: BYAPR10MB3592:EE_ 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:BYAPR10MB2888.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(346002)(136003)(376002)(366004)(396003)(39860400002)(8676002)(86362001)(54906003)(26005)(6916009)(66556008)(66476007)(4326008)(66946007)(52116002)(6506007)(8936002)(6512007)(2906002)(186003)(53546011)(6486002)(38100700002)(5660300002)(107886003)(2616005)(41300700001)(966005)(316002)(478600001)(36756003)(38350700002)(6666004);DIR:OUT;SFP:1101; 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We are changing GCC to encode the linkage info in vlen for these types. Thanks for reporting this. > GCC is wrong, clearly. This function is global ([0]) and libbpf > expects it to be marked as such in BTF. > > https://github.com/systemd/systemd/blob/main/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.c#L42-L50 > > >> GCC: >> >> [1] INT 'signed char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN >> [2] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=CHAR >> [3] TYPEDEF '__u8' type_id=2 >> [4] CONST '(anon)' type_id=3 > > [...]