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 37CB0C433E7 for ; Fri, 28 Aug 2020 11:38:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EF1B220848 for ; Fri, 28 Aug 2020 11:38:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pjn/h9gD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF1B220848 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 829746B0007; Fri, 28 Aug 2020 07:38:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7B2CA6B0008; Fri, 28 Aug 2020 07:38:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 67B116B000A; Fri, 28 Aug 2020 07:38:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0051.hostedemail.com [216.40.44.51]) by kanga.kvack.org (Postfix) with ESMTP id 4A41B6B0007 for ; Fri, 28 Aug 2020 07:38:06 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 075ED4DDA for ; Fri, 28 Aug 2020 11:38:06 +0000 (UTC) X-FDA: 77199778572.22.pear56_4b0865b27075 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id CB75B18038E67 for ; Fri, 28 Aug 2020 11:38:05 +0000 (UTC) X-HE-Tag: pear56_4b0865b27075 X-Filterd-Recvd-Size: 4802 Received: from mail-il1-f194.google.com (mail-il1-f194.google.com [209.85.166.194]) by imf31.hostedemail.com (Postfix) with ESMTP for ; Fri, 28 Aug 2020 11:38:05 +0000 (UTC) Received: by mail-il1-f194.google.com with SMTP id v2so566448ilq.4 for ; 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=KWtsPCETLMvDbcKpUbINO9bJ1DsfwYGlhGMa6Zmq7Zl5WSaIVitdiHZbzsy/NZNe70 yD5ptOhRujIEKl4Fu3Oj8XBkm5TgBCDvJw8ZYxOq9SqnVahvn3kcFV0e28IXNokFas+Y CQf1BboyLgoXgbnjYAsy+fm6E98VpJ/Dm0JgpcutVPhQlPNmMEmXDPEoJ/Tm4AZHCjYf A2kiwzmGSvYDMKQIMqHgPPxg/rMYbM4ZthxyuaCpG5x2hMKRnnsOyisZWsqZiSmiVyeO zIbfXONIswXi37z3IIBIpeBF1qZTVDvZM8Ir++NYqtXmamB0ErJoaeTXo7HKAGyFDw+C IQ2w== X-Gm-Message-State: AOAM533/c0argAwD7OuoFaCzx46O1AfvV5j8DEEZIpSEpl1x6ec6ctDo +iArGmBDL958oFuBWGFK0acuhI7gMFpef1sIjpI= 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" X-Rspamd-Queue-Id: CB75B18038E67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.