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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 C7B9CC43331 for ; Thu, 2 Apr 2020 13:04:36 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 23F9F20675 for ; Thu, 2 Apr 2020 13:04:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="WqKQxAEQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23F9F20675 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18380-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 22430 invoked by uid 550); 2 Apr 2020 13:04:28 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 22398 invoked from network); 2 Apr 2020 13:04:28 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585826661; bh=/T9PKpOsqkG6k9SDIldwzv8zPCYWoDaXHjHgeVFb4nM=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=WqKQxAEQJcb0Y8B6c/brLQqu7z26a4AWVIOnBH6hst0XYKrpnqSPctRPLxvBbJx1T K+GrF3WWgA2LuQMVoeNcHHXCYMfcP1kmTfV7M6XLEsG3cdtSkpNc+LYB95a79a/UNZ LLyAwqt9NELgCw3AazG9YJhMgszChb+SK296WGMU= X-Gm-Message-State: AGi0PuYLkMI+2xc3nJj3XYoE73hfdfH6cHU2msP95kE0yrZ/7Svtcgxu OVS4sUMuMXj1Xjvlq7WtOBCUI/0VuJ33a7ied0M= X-Google-Smtp-Source: APiQypJHMEeM/iwsXUykwckvb2/MexzqNtnc3JITmwdvurwhg/ZxuCdS12G9sOMN03deRyuepi8qA8BHF3yMJqLCXLE= X-Received: by 2002:a05:6602:2439:: with SMTP id g25mr2369114iob.142.1585826660620; Thu, 02 Apr 2020 04:24:20 -0700 (PDT) MIME-Version: 1.0 References: <20200329141258.31172-1-ardb@kernel.org> <20200402111502.GC21087@mbp> In-Reply-To: <20200402111502.GC21087@mbp> From: Ard Biesheuvel Date: Thu, 2 Apr 2020 13:24:09 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH] arm64: remove CONFIG_DEBUG_ALIGN_RODATA feature To: Catalin Marinas Cc: Linux ARM , kernel-hardening@lists.openwall.com, Will Deacon , Mark Rutland Content-Type: text/plain; charset="UTF-8" On Thu, 2 Apr 2020 at 13:15, Catalin Marinas wrote: > > On Sun, Mar 29, 2020 at 04:12:58PM +0200, Ard Biesheuvel wrote: > > When CONFIG_DEBUG_ALIGN_RODATA is enabled, kernel segments mapped with > > different permissions (r-x for .text, r-- for .rodata, rw- for .data, > > etc) are rounded up to 2 MiB so they can be mapped more efficiently. > > In particular, it permits the segments to be mapped using level 2 > > block entries when using 4k pages, which is expected to result in less > > TLB pressure. > > > > However, the mappings for the bulk of the kernel will use level 2 > > entries anyway, and the misaligned fringes are organized such that they > > can take advantage of the contiguous bit, and use far fewer level 3 > > entries than would be needed otherwise. > > > > This makes the value of this feature dubious at best, and since it is not > > enabled in defconfig or in the distro configs, it does not appear to be > > in wide use either. So let's just remove it. > > > > Signed-off-by: Ard Biesheuvel > > Happy to take this patch via the arm64 tree for 5.7 (no new > functionality), unless you want it to go with your other relocation > login in the EFI stub patches. > If you don't mind taking it for v5.7, please go ahead.