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=-2.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=unavailable 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 699FBC282E1 for ; Fri, 19 Apr 2019 21:41:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 346C721736 for ; Fri, 19 Apr 2019 21:41:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jUszBdaw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726307AbfDSVl1 (ORCPT ); Fri, 19 Apr 2019 17:41:27 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:37446 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726126AbfDSVl0 (ORCPT ); Fri, 19 Apr 2019 17:41:26 -0400 Received: by mail-pl1-f196.google.com with SMTP id w23so3112034ply.4; Fri, 19 Apr 2019 14:41:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=nurtyoNn6lnVEbXsKkEKpfnPO2VtXW7uDiD2xO1ROEw=; b=jUszBdaw5kdk4AlG1NtvQMmHYYU4JF2wzSNn5IOYE4LusFSFcu7AY9QfofcfVCpO4o blRZgLXScE7TUU3AeuEDO21J/HKgbznsOtgi7jXhfiPn+xoxmabVohggE5l1ZW4cNAKY oakRF1Vl6eHNlGOxkiF8f5mc/Ki/PA5z7Eq3i7UQNZVIC3ALQ751sVVw3G6lLP1Dopk0 0Fx0ENAGjcrn+EJI01IGzHyO8U50j5iTfuKPkKK45jWdlLfQPrQM+5EyWSFtQ/NSrxmu IiDsd4GXmVSLWiJhHIK6tEWzGnwGJpRKOHlI+RYoVLDalOyObGNSmwY60deN9NOQlxjT mdXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=nurtyoNn6lnVEbXsKkEKpfnPO2VtXW7uDiD2xO1ROEw=; b=BEm8PJ+JZrRl7E47q7usJDbOwAWlOKoquCEKSE9rnSJuIyYRJRrhxD0n/JAYd6h9Tr WZGOc2OCY+FoT4XD084xYspn5qx/o9hgL7+UWiX/bLcj9kfXV9fWVoxIffJ1gEmrs+zZ 1+Pwr16jF5uznw4PTC+kXyHPqQtmMMgt5EG30DeSaX6LcrfewXC24ELV+04wOnzG8HNt xcwCt6wILRVimeELyr205yWWIFWwxakRWguwAy3pGpeRLIT9ZqJXF4KtSqziSZc4ANOF kZu8ebdBzO4lzhRDcSdlKpZ/mILs1MAAAR25XtybPnQpJ7W97/Z0DmI+lLRk6sCQTfcW kXEA== X-Gm-Message-State: APjAAAVZBgDq1JfonDENvVHUN9R584pPKonWwil7/8C9od+n5AdTpKPJ TXblqrkJG/yuEdTWYW5rHbo= X-Google-Smtp-Source: APXvYqwGcA1E4So9MP/KyQkT1tt0/GfMN8Amjy92NJTs/iQdWyU1ighl7uyVUdQ0GeAdOEW40RxMmw== X-Received: by 2002:a17:902:7785:: with SMTP id o5mr6067219pll.33.1555710085482; Fri, 19 Apr 2019 14:41:25 -0700 (PDT) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:200::6f64]) by smtp.gmail.com with ESMTPSA id g2sm9636681pfd.134.2019.04.19.14.41.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Apr 2019 14:41:24 -0700 (PDT) Date: Fri, 19 Apr 2019 14:41:23 -0700 From: Alexei Starovoitov To: Jakub Kicinski Cc: Jiong Wang , daniel@iogearbox.net, bpf@vger.kernel.org, netdev@vger.kernel.org, oss-drivers@netronome.com Subject: Re: [PATCH v4 bpf-next 02/15] bpf: mark lo32 writes that should be zero extended into hi32 Message-ID: <20190419214121.2rbmmms6qozmiuke@ast-mbp.dhcp.thefacebook.com> References: <1555349185-12508-1-git-send-email-jiong.wang@netronome.com> <1555349185-12508-3-git-send-email-jiong.wang@netronome.com> <20190418235747.jv4yocuf6fgwahli@ast-mbp.dhcp.thefacebook.com> <20190419134051.71eeea08@cakuba.netronome.com> <20190419211403.6iovh26bu6cg2x36@ast-mbp.dhcp.thefacebook.com> <20190419143310.6c749160@cakuba.netronome.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190419143310.6c749160@cakuba.netronome.com> User-Agent: NeoMutt/20180223 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Apr 19, 2019 at 02:33:10PM -0700, Jakub Kicinski wrote: > On Fri, 19 Apr 2019 14:14:05 -0700, Alexei Starovoitov wrote: > > > This reminds me, I'm not entirely clear on the need to propagate the > > > zext through stack slots... Pointers are guaranteed to be 64bit, we > > > don't save parentage on scalars (AFAICT), > > > > scalars have parentage chain too. > > we don't track them precisely when they're spilled to stack. > > That actually caused an issue recently when valid program was rejected, > > so we might add a feature to track full contents of scalars in the stack. > > Interesting.. > > > > why not pass REG_LIVE_READ > > > or READ64 to mark_reg_read() from stack_read? > > > > can we agree on only two states first ? ;) > > Yess, the LIVE_READ was thought to be more of a mask for those accesses > that only care about "any read" being set, to be honest. As you said > read64 is a strict superset of read32. Keeping the name REG_LIVE_READ, > rather than REG_LIVE_READ_ANY or _MASK let us leave some of the > existing code untouched. > > Jiong's original idea was to add a read32, and have read mean read64. > > I think you said we should have read32 and read64 flags, but clear > read32 once read64 gets set? SGTM! yep. any subsequent read64 means that earlier read32 marks are irrelevant from zext optimization pov.