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=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 4C45FC433E2 for ; Fri, 28 Aug 2020 11:39:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2663620848 for ; Fri, 28 Aug 2020 11:39:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pjn/h9gD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729216AbgH1LjR (ORCPT ); Fri, 28 Aug 2020 07:39:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57438 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729268AbgH1LiM (ORCPT ); Fri, 28 Aug 2020 07:38:12 -0400 Received: from mail-il1-x144.google.com (mail-il1-x144.google.com [IPv6:2607:f8b0:4864:20::144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74D0EC061232; Fri, 28 Aug 2020 04:38:05 -0700 (PDT) Received: by mail-il1-x144.google.com with SMTP id t4so578325iln.1; Fri, 28 Aug 2020 04:38:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=YkhG0d/qOT3/PWJBg69FZnqsmWy5PRGz7aCU+rLDXxM=; b=pjn/h9gD/HjPLZEqJAJsF2uf24PYQdDAWmiD1wPfNvudgPxGPyd4OzHlALIT+VSh5Y T1zcvcf/2OMybRQ2gT7gBjFIjjRInfx9UkYnnINep6/pptBICO/GXDmFxw0v7PeiW4wu XDkRvqRvF6dHqX/VMJ7Qse/4QKYNFSQJSGuTljEs4hS0CsaRzZHiJRn515VXp64VUyHo mUROMmrauEJmNQQXeTDOGVVV/4ge7l3vFWlkNU5rIlNJrK6Y2W9Lp4B2rTeyXqaieX2Y nXNYq1z4Vsdd0w5W3dTDzbIzp/Y2343ZT6F4T5GYEDa/0jKrQnYPkFGbTDr0W4yLGmCr XMHQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=YkhG0d/qOT3/PWJBg69FZnqsmWy5PRGz7aCU+rLDXxM=; b=qobOkPolgRwz6XBHweJZq2qYVObyAJizRjhB0srUoh08mGQ6mw6XjhawUF23MAYjs5 2ciKvZHkw0KAx3QEhUVpXDLBkN2TnPi8SiJF3fEzpnddEB/76DwmqPI3HEpRNeT2GwYh G/ng4c1WqlJXJl81bxAjp0d+Qc7Tu/qiPrUpSyn8QuufkpBkjjs2FsCzUOsCFLuJ2eWV Sw4LfBvEjtsu4Q9Eku/ajvNk8TvhB1McGb9f8NKrfDKPUmfMW9ptfjLZzySFaMwJxSVm n6bjgLQx6Q/Q2xm2oe7HsxxnulIE3FRU+PJEMhaj8ouebE2yUw5JY/j1Iyi09rR3CWJd 3OeQ== X-Gm-Message-State: AOAM5301TYOwcegUa9vpG9udVlQ0j0FCyjE4GHzfdRMcnYSCJMplzXro lA6EFoYg2kvoK1qyq+2P5huZi+kARj0MuxDyTLM= X-Google-Smtp-Source: ABdhPJwHi2iqfV/mS52ggNLcex3m9VMBQ2/QGNsUdS0LRP4Op+NbUqXOoljtmaRM1TqvP73cHCEfd4beFso+xHIV+0Y= X-Received: by 2002:a05:6e02:586:: with SMTP id c6mr1122698ils.13.1598614684703; Fri, 28 Aug 2020 04:38:04 -0700 (PDT) MIME-Version: 1.0 References: <4BDFD364-798C-4537-A88E-F94F101F524B@amacapital.net> <87v9h3thj9.fsf@oldenburg2.str.redhat.com> In-Reply-To: <87v9h3thj9.fsf@oldenburg2.str.redhat.com> From: "H.J. Lu" Date: Fri, 28 Aug 2020 04:37:28 -0700 Message-ID: Subject: Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack To: Florian Weimer Cc: Andy Lutomirski , "Yu, Yu-cheng" , Dave Martin , Dave Hansen , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , LKML , "open list:DOCUMENTATION" , Linux-MM , linux-arch , Linux API , Arnd Bergmann , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Weijiang Yang Content-Type: text/plain; charset="UTF-8" Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Thu, Aug 27, 2020 at 11:24 PM Florian Weimer wrote: > > * H. J. Lu: > > > Can you think of ANY issues of passing more arguments to arch_prctl? > > On x32, the glibc arch_prctl system call wrapper only passes two > arguments to the kernel, and applications have no way of detecting that. > musl only passes two arguments on all architectures. It happens to work > anyway with default compiler flags, but that's an accident. In the current glibc, there is no arch_prctl wrapper for i386. There are arch_prctl wrappers with 2 arguments for x86-64 and x32. But this isn't an issue for glibc since glibc is both the provider and the user of the new arch_prctl extension. Besides, long syscall(long number, ...); is always available. -- H.J.