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=-14.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 E5BA0C433DF for ; Thu, 27 Aug 2020 16:17:38 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 AF3FE2177B for ; Thu, 27 Aug 2020 16:17:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BpiDuNHe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF3FE2177B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60520 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kBKan-0006zx-Td for qemu-devel@archiver.kernel.org; Thu, 27 Aug 2020 12:17:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39210) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kBKaF-0006Zb-Sg for qemu-devel@nongnu.org; Thu, 27 Aug 2020 12:17:03 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:51465 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kBKaD-0006w5-Id for qemu-devel@nongnu.org; Thu, 27 Aug 2020 12:17:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598545020; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wvjIJZtqLcW4H7zem9wdtUQ/NTkZKhpBp9YluL5XSWs=; b=BpiDuNHecm+L70nZEOUJogcIlONlK3tJMXXMJOks//31sxNpekUBba1xQf7DY/nDq1ndAo RZEx+mJM4SXJ28edaCCsU0MgKdvMnc6I5ivc+HCyB+0QTq1PUjU0sYTaR/aN1X7BdgJ5IE WMoKDINsUXkPdPy+3mBOIts0At9RR3w= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-161-_xU0mbSCNgyrN3Bwv0DhnA-1; Thu, 27 Aug 2020 12:16:57 -0400 X-MC-Unique: _xU0mbSCNgyrN3Bwv0DhnA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 89D671DDFF; Thu, 27 Aug 2020 16:16:56 +0000 (UTC) Received: from thuth.remote.csb (ovpn-112-56.ams2.redhat.com [10.36.112.56]) by smtp.corp.redhat.com (Postfix) with ESMTP id E0D1C10013D0; Thu, 27 Aug 2020 16:16:55 +0000 (UTC) Subject: Re: [PATCH RFC v2 3/4] pc-bios: s390x: Save io and external new PSWs before overwriting them To: Janosch Frank , qemu-devel@nongnu.org References: <20200827093152.3026-1-frankja@linux.ibm.com> <20200827093152.3026-4-frankja@linux.ibm.com> <3428e0f6-43a1-b509-d804-fad083c21cb8@linux.ibm.com> From: Thomas Huth Message-ID: <741b1d4f-1d01-2ec8-77b7-183e08a56aec@redhat.com> Date: Thu, 27 Aug 2020 18:16:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <3428e0f6-43a1-b509-d804-fad083c21cb8@linux.ibm.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Received-SPF: pass client-ip=207.211.31.81; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/27 00:53:04 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -47 X-Spam_score: -4.8 X-Spam_bar: ---- X-Spam_report: (-4.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.959, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-1.782, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 27/08/2020 16.30, Janosch Frank wrote: > On 8/27/20 2:52 PM, Thomas Huth wrote: >> On 27/08/2020 11.31, Janosch Frank wrote: >>> Currently we always overwrite the mentioned exception new PSWs before >>> loading the enabled wait PSW. Let's save the PSW before overwriting >>> and restore it right before starting the loaded kernel. >>> >>> Signed-off-by: Janosch Frank >>> --- >>> >>> Maybe we should rather statically allocate a lowcore so we don't dirty >>> 0x0 at all. >>> >>> --- >>> pc-bios/s390-ccw/jump2ipl.c | 3 ++ >>> pc-bios/s390-ccw/start.S | 62 +++++++++++++++++++++++++++---------- >>> 2 files changed, 48 insertions(+), 17 deletions(-) >>> >>> diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c >>> index 143d027bf7..a44f3ab5b3 100644 >>> --- a/pc-bios/s390-ccw/jump2ipl.c >>> +++ b/pc-bios/s390-ccw/jump2ipl.c >>> @@ -13,12 +13,15 @@ >>> #define KERN_IMAGE_START 0x010000UL >>> #define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_64) >>> >>> +extern uint64_t *psw_save_io, *psw_save_ext; >> >> I think that should be >> >> extern uint64_t psw_save_io[], psw_save_ext[]; >> >> instead ... otherwise you'll end up with some funny bugs here, won't you? > > What kind of bugs are you expecting? Well, "extern uint64_t var[];" and "extern uint64_t *var;" are two different kind of things. One is an array, one is a pointer variable. Looking at your assembler code, you obviously tried to declare an array there, not a pointer variable. Have a try with this test program: #include extern unsigned long *var; void main(void) { asm volatile (" nop ; nop ; nop "); /* marker */ memcpy((void *)0x1f0, var, 16); asm volatile (" nop ; nop ; nop "); /* marker */ } After compiling that with -O2, and disassembling the corresponding .o file, I get this code between the nops: c: c4 18 00 00 00 00 lgrl %r1,c e: R_390_PC32DBL var+0x2 12: e7 00 10 00 00 06 vl %v0,0(%r1) 18: e7 00 01 f0 00 0e vst %v0,496 The "lgrl %r1,var" is likely not what you wanted here. If you now replace the "*var" with "var[]", you get this instead: c: c0 10 00 00 00 00 larl %r1,c e: R_390_PC32DBL var+0x2 12: e7 00 10 00 00 06 vl %v0,0(%r1) 18: e7 00 01 f0 00 0e vst %v0,496 "larl" looks better now, doesn't it? >> >>> uint64_t *reset_psw = 0, save_psw, ipl_continue; >>> >>> static void jump_to_IPL_2(void) >>> { >>> /* Restore reset PSW and io and external new PSWs */ >> >> Ok, now the comment makes sense :-) >>> *reset_psw = save_psw; >>> + memcpy((void *)0x1f0, psw_save_io, 16); >>> + memcpy((void *)0x1b0, psw_save_ext, 16); >> >> Could you use &lowcore->external_new_psw and &lowcore->io_new_psw >> instead of the magic numbers? > > I can, but that means that I need to declare lowcore in netmain.c as > well as including s390-arch.h If that does not cause any other big hurdles, I think I'd prefer that instead of using magic numbers. Thanks, Thomas