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Peter Anvin" , xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org References: <20220622161048.4483-1-jgross@suse.com> <20220622161048.4483-3-jgross@suse.com> From: Jan Beulich In-Reply-To: <20220622161048.4483-3-jgross@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: AS9PR06CA0110.eurprd06.prod.outlook.com (2603:10a6:20b:465::29) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: a0832061-a9d2-4ef4-e581-08da54efa7d1 X-MS-TrafficTypeDiagnostic: AM6PR04MB5462:EE_ X-LD-Processed: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba,ExtFwd X-Microsoft-Antispam-PRVS: 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:VE1PR04MB6560.eurprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(396003)(376002)(39860400002)(136003)(366004)(346002)(478600001)(53546011)(6636002)(2906002)(6512007)(6862004)(38100700002)(4744005)(2616005)(41300700001)(6506007)(31686004)(8936002)(36756003)(66556008)(5660300002)(37006003)(26005)(8676002)(66946007)(31696002)(6486002)(186003)(4326008)(316002)(54906003)(66476007)(86362001)(45980500001)(43740500002);DIR:OUT;SFP:1101; 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This reads contradictively: If the area was put in .bss, it would be cleared. Thing is it is put in .bss..brk in the object files, while the linker script puts it in .brk (i.e. outside of .bss). > As the brk area is used to allocate early page tables, these > might contain garbage in not explicitly written entries. I'm surprised this lack of zero-initialization didn't cause any issue outside of PV Xen. Unless of course there never was the intention for users of the facility to assume blank pages coming from there, in which case Xen's use for early page tables would have been wrong (in not explicitly zeroing the space first). Jan