From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 16D77C021B8 for ; Tue, 4 Mar 2025 09:47:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=JV3pZtApgs6TqusViUPy5JRin7FrjXxYFUIaUJ+B9XQ=; b=SAxefWSRP1vNIklhn8fkSiTIBZ DFG1I7EtsUhZH2W2TF70U//ao+vUFbLcOw9K/36otCqh01vv7FOkKveNeGNs+P76W1R45qKYUV0Pq 3d39Rte6g5nSitlEEb17zTTP/+fztgs+cbBspeg/pska1+tVFJH5J8SLRik1wFHGqUbXrwsKSPBSh g0OitXNFgE980Vt0IsqOe0VDYb0BxQ7+Pe490ZGuII7tjG8lfWkaq4aEQ5XqCUsWEfub+QZeQrX+r EiZK9rO93LbqyRp+EJ+pNFck1urdDvRnLEVLcEPPCgaO69lAv/iZhMAz1lwQYksFT0vRr9+MqHmrH TmBgzXpg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tpOrU-00000003yNh-1kz5; Tue, 04 Mar 2025 09:46:52 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tpOnF-00000003wlw-2Wdk for linux-arm-kernel@bombadil.infradead.org; Tue, 04 Mar 2025 09:42:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=JV3pZtApgs6TqusViUPy5JRin7FrjXxYFUIaUJ+B9XQ=; b=sAD73dR4uuNhAcshhcuRcesBx+ eJ/C3bmv3pIIe/mG1mLKwsxL767vF9XoYK+XuLoxcB4ZcWd01zg+ESguKuTlE8fSe3DBCudwCK4QH tUYunxwMMarMT59PtDZe7o+MBlfFzUHHgWTAWR/HFTAFBcE2XGKUZOY9ifY73IjijaOidM6spsxSE TFf3w0Ou4GRQUfvuK5g12RRqcEKAkz1yfN6u5AVhvvF8TmSgpmxj7ZOfmMqoCfnW2dmEM2XmvjPlQ vWR3ZzKEgCa2Xwz1NeUER743p8ylHJVVYcWFyw0T6x121cHcZEOlLl6WIzyfEXcfnVEJRzfC1fAmf rCLuWuRQ==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tpOn8-00000000YOw-0yQv; Tue, 04 Mar 2025 09:42:22 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 5C1F230049D; Tue, 4 Mar 2025 10:42:20 +0100 (CET) Date: Tue, 4 Mar 2025 10:42:20 +0100 From: Peter Zijlstra To: Menglong Dong Cc: rostedt@goodmis.org, mark.rutland@arm.com, alexei.starovoitov@gmail.com, catalin.marinas@arm.com, will@kernel.org, mhiramat@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, jolsa@kernel.org, davem@davemloft.net, dsahern@kernel.org, mathieu.desnoyers@efficios.com, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, morbo@google.com, samitolvanen@google.com, kees@kernel.org, dongml2@chinatelecom.cn, akpm@linux-foundation.org, riel@surriel.com, rppt@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v4 1/4] x86/ibt: factor out cfi and fineibt offset Message-ID: <20250304094220.GC11590@noisy.programming.kicks-ass.net> References: <20250303132837.498938-1-dongml2@chinatelecom.cn> <20250303132837.498938-2-dongml2@chinatelecom.cn> <20250303165454.GB11590@noisy.programming.kicks-ass.net> <20250304053853.GA7099@noisy.programming.kicks-ass.net> <20250304061635.GA29480@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@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-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Mar 04, 2025 at 03:47:45PM +0800, Menglong Dong wrote: > We don't have to select FUNCTION_ALIGNMENT_32B, so the > worst case is to increase ~2.2%. > > What do you think? Well, since I don't understand what you need this for at all, I'm firmly on the side of not doing this. What actual problem is being solved with this meta data nonsense? Why is it worth blowing up our I$ footprint over. Also note, that if you're going to be explaining this, start from scratch, as I have absolutely 0 clues about BPF and such.