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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 8DD58C43142 for ; Wed, 27 Jun 2018 05:34:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 374F423D66 for ; Wed, 27 Jun 2018 05:34:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 374F423D66 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752438AbeF0Fd7 (ORCPT ); Wed, 27 Jun 2018 01:33:59 -0400 Received: from ozlabs.org ([203.11.71.1]:51513 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750909AbeF0Fd6 (ORCPT ); Wed, 27 Jun 2018 01:33:58 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPSA id 41Fs5h5dWjz9s0w; Wed, 27 Jun 2018 15:33:44 +1000 (AEST) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au From: Michael Ellerman To: Ard Biesheuvel , linux-kernel@vger.kernel.org Cc: Ard Biesheuvel , Arnd Bergmann , Kees Cook , Will Deacon , Thomas Garnier , Thomas Gleixner , "Serge E. Hallyn" , Bjorn Helgaas , Benjamin Herrenschmidt , Russell King , Paul Mackerras , Catalin Marinas , Petr Mladek , Ingo Molnar , James Morris , Andrew Morton , Nicolas Pitre , Josh Poimboeuf , Steven Rostedt , Sergey Senozhatsky , Linus Torvalds , Jessica Yu , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: Re: [PATCH v9 0/6] add support for relative references in special sections In-Reply-To: <20180626182802.19932-1-ard.biesheuvel@linaro.org> References: <20180626182802.19932-1-ard.biesheuvel@linaro.org> Date: Wed, 27 Jun 2018 15:33:44 +1000 Message-ID: <87r2ks6bev.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ard Biesheuvel writes: > This adds support for emitting special sections such as initcall arrays, > PCI fixups and tracepoints as relative references rather than absolute > references. This reduces the size by 50% on 64-bit architectures, but > more importantly, it removes the need for carrying relocation metadata > for these sections in relocatable kernels (e.g., for KASLR) that needs > to be fixed up at boot time. On arm64, this reduces the vmlinux footprint > of such a reference by 8x (8 byte absolute reference + 24 byte RELA entry > vs 4 byte relative reference) ... > > Cc: Arnd Bergmann > Cc: Kees Cook > Cc: Will Deacon > Cc: Michael Ellerman This seems to be working on powerpc. It boots on a couple of machines with no obvious badness. And there's some size reduction with a random config I had lying around: Total: Before=14820494, After=14673313, chg -0.99% It can get some more testing once it's in linux-next as far as I'm concerned. Acked-by: Michael Ellerman (powerpc) cheers