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 B6B91C433EF for ; Fri, 12 Nov 2021 20:41:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 94E1C60EBD for ; Fri, 12 Nov 2021 20:41:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235554AbhKLUoC (ORCPT ); Fri, 12 Nov 2021 15:44:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231968AbhKLUn7 (ORCPT ); Fri, 12 Nov 2021 15:43:59 -0500 Received: from mail-ed1-x52c.google.com (mail-ed1-x52c.google.com [IPv6:2a00:1450:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69C3EC061766 for ; Fri, 12 Nov 2021 12:41:08 -0800 (PST) Received: by mail-ed1-x52c.google.com with SMTP id x15so42580473edv.1 for ; Fri, 12 Nov 2021 12:41:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JBexy6By+IDrzYml2cSyJQNCDSqFJvGVfsO9tJKX2J4=; b=QY4qjhwn6x99z5bLD7KOzzqVb482QKLVZEWjKWbjrjJ73xK2C7ymYChU64S/Vfp18k E1xju4Vpr2u35t3AKPcfSVAEEFcGXXJXQSFZxmVDcOymATTxpZi8WUji3/a/dmzEOpcW CPliAFfPd79penhQcta8OGxw76X9/4DtTttbo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JBexy6By+IDrzYml2cSyJQNCDSqFJvGVfsO9tJKX2J4=; b=Ubx+KRu1EEDtlHiKV+xo6aKeioYCF5ktu8s1AAc5sD/sr/XvcIXLGajkKugUenIOBn t7vpjHmwlBQRyv+8voudIWBD9p47JUvtakJDsY+YdTvd0L9lhq96idPc7Q/FvBCNR/7h V8N1CSpsD5Ru0wKrkyC7oO292yuPFefsXZG3h5DLrzFgebVjq0+zF5CHELCILZq8pj6I cGJ2P8boWZocy06Uzf2q3p5OcpBcjFShYn+pS7WNPKQARBWtbydBIoB4qHFzSxmVUgSS +sjcaHRyLfPLS/PHtXcJrhMJs8++tyPqKHj00iwmgnc50j6/dr93eaCy8GuAIAMLKROI qyxQ== X-Gm-Message-State: AOAM533xkJe9dGOSyXX4pvJZha3D4NY8iHijyXA6wlDtBnAOb5nEuSvA pZmaVKqawffX4qQi4sw5QtneK+1xBghk9ABKpTs= X-Google-Smtp-Source: ABdhPJyg6Fh1tXLbUezdTmvVefh8DTi11XdK00zpGc6FAnXgZas5T7K4aajH4+/yN/e7x7DEOjX3+g== X-Received: by 2002:a17:906:ece9:: with SMTP id qt9mr18572913ejb.362.1636749666503; Fri, 12 Nov 2021 12:41:06 -0800 (PST) Received: from mail-wr1-f48.google.com (mail-wr1-f48.google.com. [209.85.221.48]) by smtp.gmail.com with ESMTPSA id jx2sm1888970ejc.122.2021.11.12.12.41.04 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Nov 2021 12:41:04 -0800 (PST) Received: by mail-wr1-f48.google.com with SMTP id b12so17672163wrh.4 for ; Fri, 12 Nov 2021 12:41:04 -0800 (PST) X-Received: by 2002:a5d:50c6:: with SMTP id f6mr22240639wrt.131.1636749664027; Fri, 12 Nov 2021 12:41:04 -0800 (PST) MIME-Version: 1.0 References: <87y26nmwkb.fsf@disp2133> <20211020174406.17889-9-ebiederm@xmission.com> <874k8htmb2.fsf@email.froward.int.ebiederm.org> <87ilwxrvu9.fsf@email.froward.int.ebiederm.org> In-Reply-To: <87ilwxrvu9.fsf@email.froward.int.ebiederm.org> From: Linus Torvalds Date: Fri, 12 Nov 2021 12:40:48 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 09/20] signal/vm86_32: Replace open coded BUG_ON with an actual BUG_ON To: "Eric W. Biederman" Cc: Brian Gerst , Linux Kernel Mailing List , Oleg Nesterov , Al Viro , Kees Cook , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "the arch/x86 maintainers" , H Peter Anvin , Andy Lutomirski Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 12, 2021 at 11:57 AM Eric W. Biederman wrote: > > Still user space would have had to have mapped address 0 to get that > value set in do_sys_vm86. You have to map address 0 anyway just to get vm86 mode to work. vm86 mode fundamentally requires the low 1MB of virtual memory to be mapped, since there is no virtual memory offset in the vm86 model. Linus