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=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 049E6C433E0 for ; Mon, 3 Aug 2020 16:04:36 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C66BB2068F for ; Mon, 3 Aug 2020 16:04:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="wZwucwi0"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="QHf+d+ad" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C66BB2068F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=fJ9Zxy5u+ThvO8lNnjk9/OMTGC4WNEKU0BgqsMhU9Q4=; b=wZwucwi00nkSMw49PZMn4HTA4 KVmQWSG3Hm9pGDhThQ9PsYtniyNbSyqr3S6cE2q4eagRsyRwP6fZJC6L67hFvwjZJo6aI96JKWY// D2eXTIaRov1OryUKbOZcqmBiKcfOsc8xwR7v+TkShT+vFKldmiwbVCFXEGebUcO5YXtkFGVvIVeTT B/6mSGuvjjyiQr+XOfEmtfproGHMxGLj8tZPpBQ8qLbpaixtl3JyPgW+2LUWtjPp5v6LgeVl6Hrpj kq6XuoIfk9gQuquu5iqsrej/E2A0+w/0YsHzBSpVB7dM4QagheA53Fk2UdoMMEbRAXrCqnPpkv3GI RCKo7w0lA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k2cvu-0006Oc-DN; Mon, 03 Aug 2020 16:03:26 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k2cvr-0006Nd-Hr for linux-arm-kernel@lists.infradead.org; Mon, 03 Aug 2020 16:03:24 +0000 Received: from [192.168.254.32] (unknown [47.187.206.220]) by linux.microsoft.com (Postfix) with ESMTPSA id 09D5E20B4908; Mon, 3 Aug 2020 09:03:21 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 09D5E20B4908 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1596470602; bh=ZiO52alLmnpxT7j4anLU5ZigsjFuPb9HBovKSoPQQ3w=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=QHf+d+adyjmFUMw8F6KIhtFl2KmvTj4vBrSymSBr/2bDq/bWh9j06EOVn5++PivQ+ voHvs0Lb2zIfoJuBfpScJ2evOehCf7CU8vfsuxDIGF7QhHjz3poDRcCPaEONbsDGN9 dqsnbvmNS9ytmBh/6/eiWhI5Hsbb5iwXGxjz1OIg= Subject: Re: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor To: David Laight , 'Mark Rutland' References: <20200728131050.24443-1-madvenka@linux.microsoft.com> <6540b4b7-3f70-adbf-c922-43886599713a@linux.microsoft.com> <46a1adef-65f0-bd5e-0b17-54856fb7e7ee@linux.microsoft.com> <20200731183146.GD67415@C02TD0UTHF1T.local> From: "Madhavan T. Venkataraman" Message-ID: <7fdc102e-75ea-6d91-d2a3-7fe8c91802ce@linux.microsoft.com> Date: Mon, 3 Aug 2020 11:03:21 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200803_120323_679716_AB984A19 X-CRM114-Status: GOOD ( 12.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kernel Hardening , Linux API , X86 ML , LKML , Oleg Nesterov , LSM List , Andy Lutomirski , Linux FS Devel , linux-integrity , linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 8/3/20 3:27 AM, David Laight wrote: > From: Mark Rutland >> Sent: 31 July 2020 19:32 > ... >>> It requires PC-relative data references. I have not worked on all architectures. >>> So, I need to study this. But do all ISAs support PC-relative data references? >> Not all do, but pretty much any recent ISA will as it's a practical >> necessity for fast position-independent code. > i386 has neither PC-relative addressing nor moves from %pc. > The cpu architecture knows that the sequence: > call 1f > 1: pop %reg > is used to get the %pc value so is treated specially so that > it doesn't 'trash' the return stack. > > So PIC code isn't too bad, but you have to use the correct > sequence. Is that true only for 32-bit systems only? I thought RIP-relative addressing was introduced in 64-bit mode. Please confirm. Madhavan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel