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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C51B7C38A2A for ; Fri, 8 May 2020 13:21:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4688206B9 for ; Fri, 8 May 2020 13:21:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PizcOla2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730583AbgEHNVf (ORCPT ); Fri, 8 May 2020 09:21:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1728662AbgEHMkN (ORCPT ); Fri, 8 May 2020 08:40:13 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE779C05BD43 for ; Fri, 8 May 2020 05:40:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=Af8YZ1WR9/bYbM4de2zvJhVmmyLFQbJLVbWrHU3CFbk=; b=PizcOla2stsgKNJdoQRZ34f9Z6 OVuBslDAktey2Swlehkpx5IzXJ/IGIQXGWFrkvC/ANGqKsXgSVZkzwWMPfmAaU8RaBxb6ADCR7LAY 2f+Y+G3IAXyoeGyGE3lC+jNO/Fys8OPrmTrVhN+kU4MyIGp/Xo0IBNIGbdNhr76slNtDC+G4o5HfT Z68mHB6K7UhLiwPqIEHKCfNJYlyQk1iaNv0cYlhvsDJ4b4aEj+Zh0jWmmb8OKC6mc6G/fbnN61KlD Y3xOzoih+1BmtJlCiUpqIWKw0RlimtLstrzXoPQyHz0HRJStlE75qPR8tB5k/4Vd/XnVAgV9xL/aw 6cY1m0lA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jX2IQ-0005x3-RB; Fri, 08 May 2020 12:40:07 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id F2AAC307986; Fri, 8 May 2020 14:40:04 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D936E2B843CC9; Fri, 8 May 2020 14:40:04 +0200 (CEST) Date: Fri, 8 May 2020 14:40:04 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: Josh Poimboeuf , x86@kernel.org, linux-kernel@vger.kernel.org, luto@kernel.org Subject: Re: [RFC][PATCH 3/3] x86/entry, ORC: Teach objtool/unwind_orc about stack irq swizzles Message-ID: <20200508124004.GH5281@hirez.programming.kicks-ass.net> References: <20200507161020.783541450@infradead.org> <20200507161828.801097834@infradead.org> <20200507173809.GK5298@hirez.programming.kicks-ass.net> <20200507183048.rlf2bgj4cf2g4jy6@treble> <878si3e8v2.fsf@nanos.tec.linutronix.de> <20200508101209.GY5298@hirez.programming.kicks-ass.net> <87sggak3yf.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87sggak3yf.fsf@nanos.tec.linutronix.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 08, 2020 at 02:26:32PM +0200, Thomas Gleixner wrote: > Peter Zijlstra writes: > > > On Thu, May 07, 2020 at 11:24:49PM +0200, Thomas Gleixner wrote: > >> But over our IRC conversation I came up with a 3rd variant: > >> > >> For most of the vectors the indirect call overhead is just noise, so > >> we can run them through the ASM switcher, but for the resched IPI > >> we can just use a separate direct call stub in ASM. > > > > Are we sure the rat-poison crap is noise for all the other system > > vectors? I suppose it is for most since they'll do indirect calls > > themselves anyway, right? > > We have different categories: > > 1) Uninteresting > > SPURIOUS_APIC_VECTOR, ERROR_APIC_VECTOR, THERMAL_APIC_VECTOR, > THRESHOLD_APIC_VECTOR, REBOOT_VECTOR, DEFERRED_ERROR_VECTOR > > 2) Indirect call poisoned > > LOCAL_TIMER_VECTOR > X86_PLATFORM_IPI_VECTOR > IRQ_WORK_VECTOR > HYPERV_STIMER0_VECTOR > HYPERVISOR_CALLBACK_VECTOR > POSTED_INTERRUPT_WAKEUP_VECTOR. > CALL_FUNCTION_VECTOR > CALL_FUNCTION_SINGLE_VECTOR > > 3) Quick > > RESCHEDULE_VECTOR > > POSTED_INTR_VECTOR > POSTED_INTR_NESTED_VECTOR > > These two postit ones are weird because they are both empty and > just increment different irq counts. > > HYPERV_REENLIGHTENMENT_VECTOR > > schedules delayed work, i,e. arms a timer which should be > straight forward, but does it matter? > > 4) Others > > UV_BAU_MESSAGE - The TLB flushes are probably more expensive than > ratpoutine > > Hmm? As we just agreed on IRC, 3) can run without changing stack, and then the rest can use the indirect thing.