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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E6DBC433EF for ; Fri, 15 Oct 2021 18:29:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 44AA560F36 for ; Fri, 15 Oct 2021 18:29:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242635AbhJOSb4 (ORCPT ); Fri, 15 Oct 2021 14:31:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237667AbhJOSb4 (ORCPT ); Fri, 15 Oct 2021 14:31:56 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C6ADC061570; Fri, 15 Oct 2021 11:29:49 -0700 (PDT) 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=us4YosfodZgYMwFe8rJkfXK5dBQB718M3Lke3zJ1ToY=; b=cY0CRJ4SyOUVhj9UQyVxaRjiQw /1wr6TKwpWSzfpNTEbXEKVniDAC2ka6eybM+zn4dvXDqwYkZkvTR7v491RJDKTw//hD58xTRj4oSR 0QlPPMnjn7Kj5Q69itBEQRhxFEDeXwGDeihgs8rBliRLbgQ1rALI78w76v8T7IV7afCS0Fz+4Wm/4 JqW5/oOc7BvO/34prpputAko6YLKktrYcXK5QZw27hBqOhlswQg+31OoFJIp0mMSv5a8AOMHrtuWW Noym6xZO/FLCs8cS2lPtQPTbXYrAqWX9Q1Zx+cYlupXrs+iYell2Jzqq1JcZWRqrfVcDkMJ/NiCjB zMNudW1A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mbRt6-009CM0-0J; Fri, 15 Oct 2021 18:25:17 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 90BD19857C7; Fri, 15 Oct 2021 20:24:59 +0200 (CEST) Date: Fri, 15 Oct 2021 20:24:59 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: LKML , Ingo Molnar , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Colin Ian King , Masami Hiramatsu , Nicholas Piggin , Jisheng Zhang , linux-csky@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, live-patching@vger.kernel.org, =?utf-8?B?546L6LSH?= , Guo Ren Subject: Re: [PATCH] tracing: Have all levels of checks prevent recursion Message-ID: <20211015182459.GL174703@worktop.programming.kicks-ass.net> References: <20211015110035.14813389@gandalf.local.home> <20211015161702.GF174703@worktop.programming.kicks-ass.net> <20211015133504.6c0a9fcc@gandalf.local.home> <20211015135806.72d1af23@gandalf.local.home> <20211015180429.GK174703@worktop.programming.kicks-ass.net> <20211015142033.72605b47@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211015142033.72605b47@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On Fri, Oct 15, 2021 at 02:20:33PM -0400, Steven Rostedt wrote: > On Fri, 15 Oct 2021 20:04:29 +0200 > Peter Zijlstra wrote: > > > On Fri, Oct 15, 2021 at 01:58:06PM -0400, Steven Rostedt wrote: > > > Something like this: > > > > I think having one copy of that in a header is better than having 3 > > copies. But yes, something along them lines. > > I was just about to ask you about this patch ;-) Much better :-) > diff --git a/kernel/events/internal.h b/kernel/events/internal.h > index 228801e20788..c91711f20cf8 100644 > --- a/kernel/events/internal.h > +++ b/kernel/events/internal.h > @@ -206,11 +206,7 @@ DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user) > static inline int get_recursion_context(int *recursion) > { > unsigned int pc = preempt_count(); Although I think we can do without that ^ line as well :-) > - unsigned char rctx = 0; > - > - rctx += !!(pc & (NMI_MASK)); > - rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK)); > - rctx += !!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)); > + unsigned char rctx = interrupt_context_level(); > > if (recursion[rctx]) > return -1;