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Tue, 14 Jan 2025 18:00:10 +0000 (UTC) Received: from vschneid-thinkpadt14sgen2i.remote.csb (unknown [10.39.192.55]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 79BA9195E3E0; Tue, 14 Jan 2025 17:59:46 +0000 (UTC) From: Valentin Schneider To: linux-kernel@vger.kernel.org, x86@kernel.org, virtualization@lists.linux.dev, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, linux-perf-users@vger.kernel.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org, linux-hardening@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, bpf@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com Cc: Juergen Gross , Ajay Kaher , Alexey Makhalov , Russell King , Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , Boris Ostrovsky , Josh Poimboeuf , Pawan Gupta , Sean Christopherson , Paolo Bonzini , Andy Lutomirski , Arnd Bergmann , Frederic Weisbecker , "Paul E. McKenney" , Jason Baron , Steven Rostedt , Ard Biesheuvel , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Juri Lelli , Clark Williams , Yair Podemsky , Tomas Glozar , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Kees Cook , Andrew Morton , Christoph Hellwig , Shuah Khan , Sami Tolvanen , Miguel Ojeda , Alice Ryhl , "Mike Rapoport (Microsoft)" , Samuel Holland , Rong Xu , Nicolas Saenz Julienne , Geert Uytterhoeven , Yosry Ahmed , "Kirill A. Shutemov" , "Masami Hiramatsu (Google)" , Jinghao Jia , Luis Chamberlain , Randy Dunlap , Tiezhu Yang Subject: [PATCH v4 17/30] sched/clock, x86: Mark __sched_clock_stable key as allowed in .noinstr Date: Tue, 14 Jan 2025 18:51:30 +0100 Message-ID: <20250114175143.81438-18-vschneid@redhat.com> In-Reply-To: <20250114175143.81438-1-vschneid@redhat.com> References: <20250114175143.81438-1-vschneid@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250114_180020_692333_CF9F46B5 X-CRM114-Status: GOOD ( 16.57 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Later commits will cause objtool to warn about static keys being used in .noinstr sections in order to safely defer instruction patching IPIs targeted at NOHZ_FULL CPUs. __sched_clock_stable is used in .noinstr code, and can be modified at runtime (e.g. time_cpufreq_notifier()). Suppressing the text_poke_sync() IPI has little benefits for this key, as NOHZ_FULL is incompatible with an unstable TSC anyway. Mark it to let objtool know not to warn about it. Signed-off-by: Valentin Schneider --- kernel/sched/clock.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 200e5568b9894..e59986bc14a43 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -75,8 +75,11 @@ static DEFINE_STATIC_KEY_FALSE_RO(sched_clock_running); * * Similarly we start with __sched_clock_stable_early, thereby assuming we * will become stable, such that there's only a single 1 -> 0 transition. + * + * Allowed in .noinstr as an unstable TLC is incompatible with NOHZ_FULL, + * thus the text patching IPI would be the least of our concerns. */ -static DEFINE_STATIC_KEY_FALSE(__sched_clock_stable); +static DEFINE_STATIC_KEY_FALSE_NOINSTR(__sched_clock_stable); static int __sched_clock_stable_early = 1; /*