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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by BN2PEPF00004FBB.mail.protection.outlook.com (10.167.243.181) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9115.13 via Frontend Transport; Tue, 9 Sep 2025 09:52:36 +0000 Received: from satlexmb10.amd.com (10.181.42.219) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 9 Sep 2025 02:52:36 -0700 Received: from satlexmb07.amd.com (10.181.42.216) by satlexmb10.amd.com (10.181.42.219) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 9 Sep 2025 02:52:36 -0700 Received: from [10.136.43.237] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Tue, 9 Sep 2025 02:52:32 -0700 Message-ID: <47499513-7bf0-4393-ba89-5efd9c115c43@amd.com> Date: Tue, 9 Sep 2025 15:22:31 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [patch 06/12] rseq: Implement sys_rseq_slice_yield() To: Thomas Gleixner , LKML CC: Arnd Bergmann , , Peter Zilstra , Mathieu Desnoyers , "Paul E. McKenney" , Boqun Feng , Jonathan Corbet , Prakash Sangappa , Madadi Vineeth Reddy , Steven Rostedt , Sebastian Andrzej Siewior References: <20250908225709.144709889@linutronix.de> <20250908225752.936257349@linutronix.de> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250908225752.936257349@linutronix.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN2PEPF00004FBB:EE_|SA0PR12MB4382:EE_ X-MS-Office365-Filtering-Correlation-Id: 30959a2c-edb5-447f-893b-08ddef869b7b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|82310400026|36860700013|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?dXBsbWJhTjdTNXRBRWJSWmx5VEdmWXA5czNZcGMxRDdPL3JEc2NDMmtLa2Jq?= =?utf-8?B?Nk84U2U3Mi9PNGJTbzVVbE9Ldk40REIzeDlRVEV5WEZuUER4NzZteUtPWUtF?= =?utf-8?B?UXRodWpWWmlZZU40RWRoSXJ6MElvTHlRWFpVanZmN0hCaElkTVBnWnJEb2Iv?= =?utf-8?B?a3o3UVNQZWZiRUVLbko4SWRzdXhoODVTOGRkNUkzTU54eGEzNDBTMlhNTVJ3?= =?utf-8?B?TGthVjRGajE3NU5ucjRHSjBWN2tTb3RDYjAvK0pqZG1ralBTZlY4S3VjZHRu?= =?utf-8?B?MXFZRXozTW5tblQwdENqbzFta2dTbEUyUmh5TjlwcGpLMFpVQUN3UU5jaWtX?= =?utf-8?B?TGptclM0OTdUaEJMRk5qTURzamV3Tlp2blVKQ3BSeGxiSldaN0JaLzZHLzU2?= =?utf-8?B?QS84ZExaTjEvTkMvbHV5b1RNNXVadHZ3a3FRYTNLdDdLUnlnR2YxTXRxYmZ2?= =?utf-8?B?Mld5OXpyT3JxbjVuL3pSM2VrZGtaRUhiaE96dnRiYTBKYmlTWHNvMUltcDVR?= =?utf-8?B?MmNCR1NjNzhwU0hkRS82ZjJwTEhsV1JiaW9nSFlvWWxGUXc0N1ZodXRkYmhT?= =?utf-8?B?SUsvb25NdHptVmJJOXVZbmNXcHJ0ZXYycDVubzVuNmk0M3dQRVlVY3dSdHR3?= =?utf-8?B?Z0p5c0lySk4yV21tOVlyTjEzMnhzUVR2bU5wbnlER2JxWEJwZko1bWxBM3A3?= =?utf-8?B?dUFVQ0xCTXhZaTA3YnNNWEpWMWxGZVhxNGI0Y1JZRXBoVVhVcWNjWUNWalBz?= =?utf-8?B?WE53WFZMS3ZEdXhCVy9TSWpjaUJrNWVTeXRFS1MrL1ltQnhUdWRWa3ZpL1g2?= =?utf-8?B?OVN6Y1V4SFVPK2RkcnlwdTlFSGhuaU82Q3R0TFNDQTJUM0NvNks3VXNHMzJj?= =?utf-8?B?bFlRNlA0ZzJVT1k3cHFXRWl1cmRZZ2xIU054dHpiejdWaTlSVDFEUUM2WmVM?= =?utf-8?B?Nm1UMSt0MW1aVmxRUjRpT0tIajdUL3BIOUVQMG5NOWllOUxLemhhV0szNnpY?= =?utf-8?B?OERpT1Z1aDVVV2QrZXBNQTdQZ2JyOERlQ0lIWXBjV1BHL0dvTGo3QjVnY3ov?= =?utf-8?B?YVEwcmhyc2xYdFlzS2RZRm4yQlFhdEdJU0dxV1hZeG9HdTdnc0R4Mk5IMjFZ?= =?utf-8?B?UEErc2RadWRDNGo0anB0WHNDWCtDbmovdmh4cXdBTnRRYldKTDUwSTFGcDBr?= =?utf-8?B?dTlsckM2STJ6WW1lS3VlL1JlNmdoc1Vac1RJNEJBTEUxWm5LNVpqVGYyNVZk?= =?utf-8?B?TkMvM2ovaE84WXQ3bUxpYXdiMVVrWlkzYUl6eElLeE1kUTRXM2w5VzVScWdV?= =?utf-8?B?RmsxMExUQ0NDSXJiTDFMZlA5ZUEvd214MC8zZVA0ckg3TDNzRGU2VWxPb0lm?= =?utf-8?B?MVdoSm80M01mZHhwekJLVjA4b1FUVFJEdjZpV0RsbzZZdCs5QUhONFJnbzE5?= =?utf-8?B?ZDdkRHlYaVdFMFVpVzM0UnAwcjQzN3VjQ2hmUEE0bEF5ckJvSTVnWk50eTFE?= =?utf-8?B?QkdBeW1tMWpSeVR4L3d4UVpXdXlMdmNRQ01RWVNZVlB5ZFVNL001b0M4SklI?= =?utf-8?B?NnFqMVZtWXcvYTc1ZHFzMFRNdnZLNER1azJPNFozMU1IVXg3RXJuS3pDdm9u?= =?utf-8?B?QnlLSVhmNEl6LzA1ZDBuY3oyZUVGeFRYalFBa21wV09hbS8vdFdpTmZ5Sjdw?= =?utf-8?B?MDU1NkFPUm5WOENhb3Z3MG5reDMvVXJMWlEvMUVkR2JrMFBQRXRTOFFnbklL?= =?utf-8?B?cUM2QWlEQ3UvbkE3b1kvK3p6SUQreGlKakZhQlU4ZmFUaGY4TFJqdFVlRmxv?= =?utf-8?B?SXJNbXZUeVdUSy9uK1NveW52NEN2QzZsSkQ4cFY5TTlUVHdPMGd6TTNheHZO?= =?utf-8?B?cDROR1Y1Tk0xMkpCZ2ZlbTRaVmo2ZzM3aDRVbkxZTGdaMDlwdkp6MS93ZldG?= =?utf-8?B?VDFWUlo2Mk5Ed0dRWHZTZjZvSTZxV3hGYi8zSjdraEVRVmRoTytYWERIYmFj?= =?utf-8?B?SUtYVjVaZk5Lc21mbkd4eEhpZDdCNmZyL0hhVmM4WFUxUXQ3WUxNRVlxSVVq?= =?utf-8?Q?zxjuEJ?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(7416014)(376014)(82310400026)(36860700013)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Sep 2025 09:52:36.9281 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 30959a2c-edb5-447f-893b-08ddef869b7b X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN2PEPF00004FBB.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR12MB4382 Hello Thomas, On 9/9/2025 4:30 AM, Thomas Gleixner wrote: > --- a/kernel/rseq.c > +++ b/kernel/rseq.c > @@ -542,6 +542,15 @@ int rseq_slice_extension_prctl(unsigned > return -EFAULT; > } > > +SYSCALL_DEFINE0(rseq_slice_yield) > +{ > + if (need_resched()) { > + schedule(); > + return 1; > + } > + return 0; > +} > + > static int __init rseq_slice_cmdline(char *str) > { > bool on; > --- a/kernel/sys_ni.c > +++ b/kernel/sys_ni.c > @@ -390,5 +390,6 @@ COND_SYSCALL(setuid16); > > /* restartable sequence */ > COND_SYSCALL(rseq); > +COND_SYSCALL(rseq_sched_yield); I'm not sure if it is my toolchain but when I try to build a version with CONFIG_RSEQ_SLICE_EXTENSION disabled, I see: ld: vmlinux.o: in function `x64_sys_call': arch/x86/include/generated/asm/syscalls_64.h:471: undefined reference to `__x64_sys_rseq_slice_yield' ld: vmlinux.o: in function `ia32_sys_call': arch/x86/include/generated/asm/syscalls_32.h:471: undefined reference to `__ia32_sys_rseq_slice_yield' ld: vmlinux.o:(.rodata+0x12d0): undefined reference to `__x64_sys_rseq_slice_yield' I would have assumed the COND_SYSCALL() above would have stubbed this but that doesn't seem to be the case. Am I missing something? P.S. I'm running with: gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04.2) GNU ld (GNU Binutils for Ubuntu) 2.38 -- Thanks and Regards, Prateek