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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [RFC PATCH 2/2] Revert "csky: Add support for restartable sequence" Content-Language: en-US From: Mathieu Desnoyers To: Guo Ren , Peter Zijlstra , paulmck , Boqun Feng Cc: linux-kernel , Alexander Viro , Linus Torvalds , "linux-csky@vger.kernel.org" References: <20210723161600.19688-1-mathieu.desnoyers@efficios.com> <20210723161600.19688-2-mathieu.desnoyers@efficios.com> <2070284546.6496.1627316900287.JavaMail.zimbra@efficios.com> In-Reply-To: <2070284546.6496.1627316900287.JavaMail.zimbra@efficios.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: YQBPR01CA0149.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:7e::13) To YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: YT2PR01MB9175:EE_|YQBPR0101MB5481:EE_ X-MS-Office365-Filtering-Correlation-Id: e4228b19-b35a-4ce1-b5c3-08da929e1360 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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This leaves out any > relevant testing of rseq per-se. With what we have in the upstream > selftests, I expect this test configuration to abort at runtime because > no slow-path fallbacks are available when the fastpath is disabled. > > The asm glue to test rseq user-space really needs to be implemented > for any useful testing to be done here. > > Unless that asm glue is contributed, none of the rseq logic is actually > tested on that architecture. > > Considering the extremely-hard-to-debug nature of races with a broken > rseq kernel implementation, proper testing coverage is paramount, so I > still recommend the revert unless the selftests user-space asm glue is > contributed for C-Sky. Hi Guo, A friendly ping after 1.5 year about the fact that the selftests code is still missing for the csky architecture. So there is no way to validate that the kernel pieces that were merged actually work on that architecture. What is the timeline for contribution of the missing bits needed to enable those tests ? Here are the required header files: tools/testing/selftests/rseq/rseq-csky.h tools/testing/selftests/rseq/rseq-csky-thread-pointer.h (only if __builtin_thread_pointer is not implemented by gcc) I'm open to suggestions from other rseq co-maintainers on how to best address this situation. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com