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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A085C433EF for ; Mon, 25 Apr 2022 17:02:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243710AbiDYRFN (ORCPT ); Mon, 25 Apr 2022 13:05:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243336AbiDYRFL (ORCPT ); Mon, 25 Apr 2022 13:05:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2C2D1C11F for ; Mon, 25 Apr 2022 10:02:06 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8DB9F614F9 for ; Mon, 25 Apr 2022 17:02:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BDDFC385A7; Mon, 25 Apr 2022 17:02:05 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="BjcCxH1g" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1650906122; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3bT9S+VY2i3onixTKTaTwovdaV7rvNqFw7jUDNK3p/o=; b=BjcCxH1gRx+XRu/oEPKS12iawQoa7VkVfSZYS/6iYyY8vZEaWIS2w+yUHhqPYhNIPFCA2q 224GimbDT7u0I8jZbx0tCBLASmPOQeOaH53zbJZEFyYByqiX1d4hdDtL8vq7yar3VrxjgV /XuavYSenfNrBYFbhOy2DWSk0X4vB5o= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 36a3af82 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Mon, 25 Apr 2022 17:02:02 +0000 (UTC) Date: Mon, 25 Apr 2022 19:01:57 +0200 From: "Jason A. Donenfeld" To: Arnd Bergmann Cc: Linux Kernel Mailing List , Nick Desaulniers Subject: Re: odd endianness toolchains for crosstool Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Arnd, On Mon, Apr 25, 2022 at 06:15:07PM +0200, Arnd Bergmann wrote: > On Mon, Apr 25, 2022 at 5:53 PM Jason A. Donenfeld wrote: > > > > Hi Arnd, > > > > On Mon, Apr 25, 2022 at 05:39:34PM +0200, Arnd Bergmann wrote: > > > I can probably do that before migrating to the new machine, but I can't > > > promise how quickly I find time to start. > > > > Oh awesome. Will keep my eye out for it. > > > > > > (And also, build ppc32 with --enable-secureplt --with-long-double-64.) > > > > > > Can you explain what those are about? Is this related to the ELFv1 > > > vs ELFv2 difference or something else? Is this needed in both the > > > ppc32 and ppc64 compilers that each come with both targets? > > > > For 32-bit, it is required. From > > : > > > > powerpc (needs gcc built with --enable-secureplt > > --with-long-double-64, and -Wl,--secure-plt to link dynamic > > binaries.) > > > > And from the INSTALL file it says: > > > > * PowerPC > > * Compiler toolchain must provide 64-bit long double, not IBM > > double-double or IEEE quad > > * For dynamic linking, compiler toolchain must be configured for > > "secure PLT" variant > > > > For 64-bit, I'm not sure, but I know that at least -mabi=elfv2 is required, > > and I think --with-long-double-64 too, according to documentation: > > > > * PowerPC64 > > * Both little and big endian variants are supported > > * Compiler toolchain must provide 64-bit long double, not IBM > > double-double or IEEE quad > > * Compiler toolchain must use the new (ELFv2) ABI regardless of > > whether it is for little or big endian > > Ok, I see. For all I can tell, the toolchain I built already uses both > --with-long-double-64 > and --enable-secureplt, as those seemt to be the default for Linux. For ppc32? I'm unable to produce working executables with the toolchain. And looking at the target info, -msecure-plt is missing, while -mlong-double-64 is there: $ ./powerpc-linux-gcc -Q --help=target | grep long-double -mlong-double- 64 $ ./powerpc-linux-gcc -Q --help=target | grep msecure-plt -msecure-plt [disabled] For ppc64, I see the same. I'll try to look into it more though. > Regarding the the ELF ABI, I'm not sure how to check, but I think it > only does ELFv1, which is the default for big-endian glibc. Yes, it only is doing ELFv1 right now. musl checks this in with this: trycppif "_CALL_ELF == 2" "$t" || fail "$0: error: unsupported powerpc64 ABI" Jason