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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 2F5EEC3F2D1 for ; Thu, 5 Mar 2020 18:17:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0551C208CD for ; Thu, 5 Mar 2020 18:17:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="iImtYUMX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726079AbgCESRX (ORCPT ); Thu, 5 Mar 2020 13:17:23 -0500 Received: from mail-wm1-f67.google.com ([209.85.128.67]:35547 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725944AbgCESRX (ORCPT ); Thu, 5 Mar 2020 13:17:23 -0500 Received: by mail-wm1-f67.google.com with SMTP id m3so6793454wmi.0 for ; Thu, 05 Mar 2020 10:17:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition :user-agent; bh=ur7gy1iBTjpshiGwn7PHFKRCZKN/EqCC/bRu0X/qyjI=; b=iImtYUMXg9gyEfPpN6j0wtKnybFmfih1SfNntEvPgSKVqSNzIWYwqVA5ucEiEzTvpD yZqKFDabhXvjfFheAMTPtlVso8ONAcoo+XtdsuRau0kiq7I3tS22meFiHsUCPX9eiUIq qDHif+8/lmfO05BuZJZpnk8Wuf8ZHkfZu1QZVtzlCn0sK2aKyP01FAoOFmJJLOppsA4l ZZJfyLFF3rcy1MUWvP79OmIFsx+KiYAzavZdud4ulwIY/zQQXdSEqImdcaJB4nuavcjy YTFsnhVjhRjxjVxYVqmZJ1b1WAbmeRnIrI4YNGhCHFN4ifXVPLL7qKzz+z1+4RB39U6N mY1w== 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:mime-version :content-disposition:user-agent; bh=ur7gy1iBTjpshiGwn7PHFKRCZKN/EqCC/bRu0X/qyjI=; b=kLh5aEy7DFpIU6g50gXVyZplQe33Gxp7ENGSDsNrLeWEOSIol2tp0E39zSpt5rHzUX mHzLWxolV2Gl7YEupwHH5EOFf80dB97b3Y21sdBwcnGDJ+k+X5RyjyC57x4Y/DNuecED MJSvVNSVjX8I3MmuwBDHrerL3BuqM2l+LOSdbsgohMcyYO2yvEons1WiN1Q0rjn6e/Vj wvz6xRSDwhK7QhofvxgH2jGG36n+2YXzTCr36TsJFYDx33DJ7iqIV6nXEwrW0SZrlJfR xCngysC/Zw8lo/RKuK48FSTE0ktr/tOY78h8UZrpnNf1RhZjgU9Mx3IcQFQPwFYgPjuR yF7w== X-Gm-Message-State: ANhLgQ2iWbkH606Asd1xpQuTc+E6BBuzGK7GQWlTs6frtHs8AIqcUxGN Url7C0T0Le6UwANxLO6N+Q== X-Google-Smtp-Source: ADFU+vsKpOKjyZZ2sdfPleEssK0P/iXY3amRp8rqYqgctOT1C2k+RMpUAPE2OoUVfiaY5pyfPriW+A== X-Received: by 2002:a1c:2ecc:: with SMTP id u195mr26937wmu.167.1583432241952; Thu, 05 Mar 2020 10:17:21 -0800 (PST) Received: from avx2 ([46.53.249.49]) by smtp.gmail.com with ESMTPSA id v7sm38843379wrm.49.2020.03.05.10.17.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Mar 2020 10:17:21 -0800 (PST) Date: Thu, 5 Mar 2020 21:17:19 +0300 From: Alexey Dobriyan To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com Cc: x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] x86_64: fixup TASK_SIZE_MAX comment Message-ID: <20200305181719.GA5490@avx2> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Comment says "by preventing anything executable" which is not true. Even PROT_NONE mapping can't be installed at (1<<47 - 4096). mmap(0x7ffffffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM I wonder if CPUs with wider address space carried the bugs... Signed-off-by: Alexey Dobriyan --- arch/x86/include/asm/processor.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -887,7 +887,7 @@ static inline void spin_lock_prefetch(const void *x) * On Intel CPUs, if a SYSCALL instruction is at the highest canonical * address, then that syscall will enter the kernel with a * non-canonical return address, and SYSRET will explode dangerously. - * We avoid this particular problem by preventing anything executable + * We avoid this particular problem by preventing anything * from being mapped at the maximum canonical address. * * On AMD CPUs in the Ryzen family, there's a nasty bug in which the