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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7D473C64EC7 for ; Tue, 28 Feb 2023 17:49:15 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.503642.775968 (Exim 4.92) (envelope-from ) id 1pX462-000180-Uh; Tue, 28 Feb 2023 17:49:02 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 503642.775968; Tue, 28 Feb 2023 17:49:02 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pX462-00017t-Qz; Tue, 28 Feb 2023 17:49:02 +0000 Received: by outflank-mailman (input) for mailman id 503642; Tue, 28 Feb 2023 17:49:00 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pX460-00017j-QJ for xen-devel@lists.xenproject.org; Tue, 28 Feb 2023 17:49:00 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pX460-0008DV-1U; Tue, 28 Feb 2023 17:49:00 +0000 Received: from 54-240-197-227.amazon.com ([54.240.197.227] helo=[192.168.12.216]) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1pX45z-0005WB-PJ; Tue, 28 Feb 2023 17:48:59 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID; bh=D0aPMIK7eB1gZTgJIWG/ri37Z8vUj9fxtEepC5SrDpM=; b=YupIBKniiEveDAG95KIuItm9rL 64b8SXeWSJDwDxXDhGAfDXPPg09W2xwo5uIXm5bkU5zJQL6fvJRE4BWiEwRpJmhDLbnyJHbZJksTW 6XTN5Qpa59UC8CU3FfiTBC3OGju16l6jgiM7DVpeOiujfXeoBu53PbndIF4E4d6C4at8=; Message-ID: <46e96dd9-bcb4-4569-b282-05c019cabcc3@xen.org> Date: Tue, 28 Feb 2023 17:48:57 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v3 3/4] xen/arm: switch ARM to use generic implementation of bug.h Content-Language: en-US To: Oleksii , xen-devel@lists.xenproject.org Cc: Jan Beulich , Andrew Cooper , Stefano Stabellini , Gianluca Guida , Bertrand Marquis , Volodymyr Babchuk References: From: Julien Grall In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Oleksii, On 28/02/2023 15:09, Oleksii wrote: > On Sat, 2023-02-25 at 16:49 +0000, Julien Grall wrote: >> Hi Oleksii, >> >> On 24/02/2023 11:31, Oleksii Kurochko wrote: >>> The following changes were made: >>> * make GENERIC_BUG_FRAME mandatory for ARM >> >> I have asked in patch #1 but will ask it again because I think this >> should be recorded in the commit message. Can you outline why it is >> not >> possible to completely switch to the generic version? > I haven't tried to switch ARM too because of comment regarding 'i' in > : > /* > * GCC will not allow to use "i" when PIE is enabled (Xen doesn't set > the > * flag but instead rely on the default value from the compiler). So > the > * easiest way to implement run_in_exception_handler() is to pass the > to > * be called function in a fixed register. > */ I would expect this comment to be valid for any arch. So if there is a need to deal with PIE, then we would not be able to use "i" in the BUG frame. Note that we are now explicitly compiling Xen without PIE (see Config.mk). Cheers, -- Julien Grall