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[213.44.141.166]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b4852400a3sm112207985a.96.2024.11.20.08.25.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Nov 2024 08:25:07 -0800 (PST) From: Valentin Schneider To: Josh Poimboeuf Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, x86@kernel.org, rcu@vger.kernel.org, linux-kselftest@vger.kernel.org, Steven Rostedt , Masami Hiramatsu , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Andy Lutomirski , Peter Zijlstra , Frederic Weisbecker , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Jason Baron , Kees Cook , Sami Tolvanen , Ard Biesheuvel , Nicholas Piggin , Juerg Haefliger , Nicolas Saenz Julienne , "Kirill A. Shutemov" , Nadav Amit , Dan Carpenter , Chuang Wang , Yang Jihong , Petr Mladek , "Jason A. Donenfeld" , Song Liu , Julian Pidancet , Tom Lendacky , Dionna Glaze , Thomas =?utf-8?Q?Wei=C3=9Fschuh?= , Juri Lelli , Marcelo Tosatti , Yair Podemsky , Daniel Wagner , Petr Tesarik Subject: Re: [RFC PATCH v3 06/15] jump_label: Add forceful jump label type In-Reply-To: <20241119233902.kierxzg2aywpevqx@jpoimboe> References: <20241119153502.41361-1-vschneid@redhat.com> <20241119153502.41361-7-vschneid@redhat.com> <20241119233902.kierxzg2aywpevqx@jpoimboe> Date: Wed, 20 Nov 2024 17:24:59 +0100 Message-ID: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: SjRiupGU6ImBeEWHwkoEBElH6jdy2TM08GpoMZhm5JQ_1732119908 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Rspam-User: X-Rspamd-Queue-Id: 1C6CE100004 X-Rspamd-Server: rspam11 X-Stat-Signature: 1tizs869qybtpjbtexan78bch4g8s6k3 X-HE-Tag: 1732119852-876410 X-HE-Meta: U2FsdGVkX1+5KEev/i2U5Z0FKBsTwwYrc8WX2MqYD7p/T3+xPWoEWqY8v0ETCF5dU2VnaHoC5qAOxAOFTUAHLNQB8BA5ON+y6620kVzrZ58JrOHn20IALPPZjAios3d9bQn6masKxXUss5LRJQeeUGTykKo0Q6VR2UDJoTIMEUly5+aM9LprfcqCrMV95o00ucFzBYgdW8xTffuNr7nPit0PurxRJPWxXjrOnmpVMOOYNCMKCaTng7ndlrMGhC9MLj5uEUJ0Qxg1NWrzNvhSY2cOabqx/1iiiokAjoZlUKlc8YDb31Wb8GdmtHAGTRO0pA8c657MrEedNr0p/Yry/kc3wSVsiCRq//5gyPm4lUqHl+6MtOycVDPz+Z57lNtldopSnOB5lBdE4QsCowNb99+2tSqVkkNmu0lcnxpplZJ5HkOf7jFDxsDmb8FkQb0V8Ti+pHiQO9DTabLtetpxcOPARyXSr/f82n16/Dk7XDZ70rN18olwCXtucHak/K2g7BTGY0Zir2Srfd1odVcce/6YEsG9LO7weQqjQQKQcjm03iStDEF6xazwQT1fAil3I3k1TY87MIR641E5+sQd4jaEUG1ooMdYbmL4cOf6OQntOeHgXQm1aZE+KNnqcN7VbHi+mk6q08pzpo96IBlNt917jtZuPhNSECvxPsfWrjAZCbAQRsOIEkNHW343FmtTBaudaYWovjPD6OG+JHdf0aKuAH2UH9BgkzLe6oUb06nQzBNUDYn5JsANZy0ngnpEJneWLO65ipGh72jhWyPGEcv7vMdMctlz+qzdhaJq696qwFwc/Yh7KJc+3+A8XKSyuGbMfS2c1VLTKbEzcRzRzC5MPHFi+PE8tLetX6MWka1c+rUUlE+pNt+29QSt1aOIvhCeIlc5Q7RWHxQ1J+N0nOhIbs++xss/psWp1QeG37a2Gh+3AW8yUjGoriPtj9HFfeptrc7bPJU8eHpCMsV rDP6sFcj qbVDVDJoeyV+KNeCxGNPk7eV6J+tz0sbOWxq2jT5X7I58C3aLKXtPXgz9HzqplXnxI0jZtRnX+GugMsVOEQpMu1fMEHAZwig8rEM4trXIplspx4zJRvaA1Gy/WrkJSlkTIRt6sV0QsxuvjiKFKvxFL/4en9mhed2/KsWRIMwYil4mwHA/rY741KVT6geZJ5Jq23DB0VZglSvn7jtjGSF6+9nYLPMRe3aXBuYJ3ZxaCfur55hLv5oXwDnHXxhukm3x30K/XRDvV/UgJM39QajA3HWoIw28/yxbgwzQO0/pXCrcNmQuJyENEvk0XGBUxAU9QYWaZFhQZT1x2oJfQn0MQdydwod64QzuhOjI2QwHi7RSh7iV6EyuxBLKrMIhnuuKrAmYwiVSfK1XnsZN07cfCfkHD5k0IJNfeneczz0QHxDJShc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 19/11/24 15:39, Josh Poimboeuf wrote: > On Tue, Nov 19, 2024 at 04:34:53PM +0100, Valentin Schneider wrote: >> Later commits will cause objtool to warn about non __ro_after_init static >> keys being used in .noinstr sections in order to safely defer instruction >> patching IPIs targeted at NOHZ_FULL CPUs. > > Don't we need similar checking for static calls? > /sifts through my notes throwing paper all around Huh, I thought I had something, but no... Per the results they don't seem to be flipped around as much as static keys, but they also end up in text_poke_bp(), so yeah, we do. Welp, I'll add that to the list. >> Two such keys currently exist: mds_idle_clear and __sched_clock_stable, >> which can both be modified at runtime. > > Not sure if feasible, but it sure would be a lot simpler to just make > "no noinstr patching" a hard rule and then convert the above keys (or at > least their noinstr-specific usage) to regular branches. > > Then "no noinstr patching" could be unilaterally enforced in > text_poke_bp(). > >> diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h >> index f5a2727ca4a9a..93e729545b941 100644 >> --- a/include/linux/jump_label.h >> +++ b/include/linux/jump_label.h >> @@ -200,7 +200,8 @@ struct module; >> #define JUMP_TYPE_FALSE 0UL >> #define JUMP_TYPE_TRUE 1UL >> #define JUMP_TYPE_LINKED 2UL >> -#define JUMP_TYPE_MASK 3UL >> +#define JUMP_TYPE_FORCEFUL 4UL > > JUMP_TYPE_NOINSTR_ALLOWED ? > That's better, I'll take it. Thanks! > -- > Josh