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Mon, 31 Jul 2023 04:16:54 -0700 (PDT) X-Google-Smtp-Source: APBJJlGotwePfsXKLeBlKhf8sO13ly4OfXrqZZNVUmXDsF4Tb1xqGBmiDGw9g/K6bGBIoBOR4Hianw== X-Received: by 2002:a67:cfc7:0:b0:443:92a5:f454 with SMTP id h7-20020a67cfc7000000b0044392a5f454mr4890212vsm.26.1690802214510; Mon, 31 Jul 2023 04:16:54 -0700 (PDT) Received: from vschneid.remote.csb ([149.12.7.81]) by smtp.gmail.com with ESMTPSA id r7-20020a0c8d07000000b0063d119034a9sm3601878qvb.140.2023.07.31.04.16.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Jul 2023 04:16:53 -0700 (PDT) From: Valentin Schneider To: Josh Poimboeuf Cc: linux-kernel@vger.kernel.org, linux-trace-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 , Daniel Bristot de Oliveira , Marcelo Tosatti , Yair Podemsky Subject: Re: [RFC PATCH v2 13/20] context_tracking: Make context_tracking_key __ro_after_init In-Reply-To: <20230728160014.vjxikkoo4rieng55@treble> References: <20230720163056.2564824-1-vschneid@redhat.com> <20230720163056.2564824-14-vschneid@redhat.com> <20230728160014.vjxikkoo4rieng55@treble> Date: Mon, 31 Jul 2023 12:16:43 +0100 Message-ID: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Rspamd-Queue-Id: 412BB40013 X-Rspam-User: X-Stat-Signature: ttnrawpu69oekuqzhzi7i7rugdheu1qb X-Rspamd-Server: rspam01 X-HE-Tag: 1690802217-386795 X-HE-Meta: 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 QnuZWo8J uHWrxVpOpR826o8QrCAgLEcup8HHfsJGAQnBO/Et3xjIQoW+gCDC1X4QQYyA8Lu87p2JIbUl9CIn+T9rGwhxtiktVD5/48/yhj/h+PNs8RPr3+3DlHLOxBVee4FZs3H5wjnaWJUiwckBA2BJiZDa2mjjjxq6shOES/fVq5UYAAlSJMyfhJXrc1vCfbgSYwhyUQEqo6Kp7s4lQg0JMq5Hb210isWZblNZaf/FJkfHL9P2JCtWWMgbcOhn04+8mONH80E2R+epZZrumQ2gk/nw6GeBzfiukHMGa3LPGjXl6SiE6ROqhlfzziZjU95q+cPYYJsYsq8+sc+b4CB4DtFOVLym2UWX8Batjdlz0No6QOp7Bp2Tmk7C4Orkq3rvuiXNvVNETozbn1nM86KbCurSYv36SRPlQdR1rlsVq 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: On 28/07/23 11:00, Josh Poimboeuf wrote: > On Thu, Jul 20, 2023 at 05:30:49PM +0100, Valentin Schneider wrote: >> objtool now warns about it: >> >> vmlinux.o: warning: objtool: enter_from_user_mode+0x4e: Non __ro_after_init static key "context_tracking_key" in .noinstr section >> vmlinux.o: warning: objtool: enter_from_user_mode+0x50: Non __ro_after_init static key "context_tracking_key" in .noinstr section >> vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0x60: Non __ro_after_init static key "context_tracking_key" in .noinstr section >> vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0x62: Non __ro_after_init static key "context_tracking_key" in .noinstr section >> [...] >> >> The key can only be enabled (and not disabled) in the __init function >> ct_cpu_tracker_user(), so mark it as __ro_after_init. >> >> Signed-off-by: Valentin Schneider > > It's best to avoid temporarily introducing warnings. Bots will > rightfully complain about that. This patch and the next one should come > before the objtool patches. > Ack, I'll reverse the order of these. > Also it would be helpful for the commit log to have a brief > justification for the patch beyond "fix the objtool warning". Something > roughly like: > > Soon, runtime-mutable text won't be allowed in .noinstr sections, so > that a code patching IPI to a userspace-bound CPU can be safely > deferred to the next kernel entry. > > 'context_tracking_key' is only enabled in __init ct_cpu_tracker_user(). > Mark it as __ro_after_init. > Looks better indeed, thanks! > -- > Josh