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=-1.0 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 76643C28CF6 for ; Wed, 1 Aug 2018 08:30:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C441120844 for ; Wed, 1 Aug 2018 08:30:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C441120844 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com 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 S2388564AbeHAKOi (ORCPT ); Wed, 1 Aug 2018 06:14:38 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:46370 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387666AbeHAKOh (ORCPT ); Wed, 1 Aug 2018 06:14:37 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w718T8lY087497 for ; Wed, 1 Aug 2018 04:30:03 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2kk47jty1d-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 01 Aug 2018 04:30:02 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 1 Aug 2018 09:29:54 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w718TrrA37879938 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 1 Aug 2018 08:29:53 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0C72552059; Wed, 1 Aug 2018 11:30:04 +0100 (BST) Received: from ThinkPad (unknown [9.152.212.29]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 5931D52050; Wed, 1 Aug 2018 11:30:03 +0100 (BST) Date: Wed, 1 Aug 2018 10:29:51 +0200 From: Philipp Rudo To: AKASHI Takahiro Cc: catalin.marinas@arm.com, will.deacon@arm.com, dhowells@redhat.com, vgoyal@redhat.com, herbert@gondor.apana.org.au, davem@davemloft.net, dyoung@redhat.com, bhe@redhat.com, arnd@arndb.de, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, ard.biesheuvel@linaro.org, james.morse@arm.com, bhsharma@redhat.com, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v13 03/16] s390, kexec_file: drop arch_kexec_mem_walk() In-Reply-To: <20180801075820.3753-4-takahiro.akashi@linaro.org> References: <20180801075820.3753-1-takahiro.akashi@linaro.org> <20180801075820.3753-4-takahiro.akashi@linaro.org> Organization: IBM X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18080108-0020-0000-0000-000002AF39E1 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18080108-0021-0000-0000-000020FB5F10 Message-Id: <20180801102951.527cfc57@ThinkPad> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-01_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1808010092 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey Akashi, I kept thinking about this patch and remembered why I didn't made the change you are suggesting now. The problem is when you only check for kbuf->mem you are excluding address 0, which might be a valid address to load the kernel to. On s390 this is actually done when the kernel is not loaded via a boot loader. For kexec_file however, we cut off the first few kB of the image and jump directly to 'startup'. So checking for !0 does not cause a problem here. Anyway, the long term safer solution would be something like #define KEXEC_BUF_MEM_UNKNOWN (-1UL) for architectures to tell common code to search a fitting mem hole. Back then I didn't do the change because I had the other workaround, which didn't require a common code change. But when you are touching the code now it is worth thinking about it. Just wanted to let you know Philipp On Wed, 1 Aug 2018 16:58:07 +0900 AKASHI Takahiro wrote: > Since s390 already knows where to locate buffers, calling > arch_kexec_mem_walk() has no sense. So we can just drop it as kbuf->mem > indicates this while all other architectures sets it to 0 initially. > > This change is a preparatory work for the next patch, where all the > variant memory walks, either on system resource or memblock, will be > put in one common place so that it will satisfy all the architectures' > need. > > Signed-off-by: AKASHI Takahiro > Reviewed-by: Philipp Rudo > Cc: Martin Schwidefsky > Cc: Heiko Carstens > Cc: Dave Young > Cc: Vivek Goyal > Cc: Baoquan He > --- > arch/s390/kernel/machine_kexec_file.c | 10 ---------- > kernel/kexec_file.c | 4 ++++ > 2 files changed, 4 insertions(+), 10 deletions(-) > > diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c > index f413f57f8d20..32023b4f9dc0 100644 > --- a/arch/s390/kernel/machine_kexec_file.c > +++ b/arch/s390/kernel/machine_kexec_file.c > @@ -134,16 +134,6 @@ int kexec_file_add_initrd(struct kimage *image, struct s390_load_data *data, > return ret; > } > > -/* > - * The kernel is loaded to a fixed location. Turn off kexec_locate_mem_hole > - * and provide kbuf->mem by hand. > - */ > -int arch_kexec_walk_mem(struct kexec_buf *kbuf, > - int (*func)(struct resource *, void *)) > -{ > - return 1; > -} > - > int arch_kexec_apply_relocations_add(struct purgatory_info *pi, > Elf_Shdr *section, > const Elf_Shdr *relsec, > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 63c7ce1c0c3e..bf39df5e5bb9 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -534,6 +534,10 @@ int kexec_locate_mem_hole(struct kexec_buf *kbuf) > { > int ret; > > + /* Arch knows where to place */ > + if (kbuf->mem) > + return 0; > + > ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback); > > return ret == 1 ? 0 : -EADDRNOTAVAIL; From mboxrd@z Thu Jan 1 00:00:00 1970 From: prudo@linux.ibm.com (Philipp Rudo) Date: Wed, 1 Aug 2018 10:29:51 +0200 Subject: [PATCH v13 03/16] s390, kexec_file: drop arch_kexec_mem_walk() In-Reply-To: <20180801075820.3753-4-takahiro.akashi@linaro.org> References: <20180801075820.3753-1-takahiro.akashi@linaro.org> <20180801075820.3753-4-takahiro.akashi@linaro.org> Message-ID: <20180801102951.527cfc57@ThinkPad> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hey Akashi, I kept thinking about this patch and remembered why I didn't made the change you are suggesting now. The problem is when you only check for kbuf->mem you are excluding address 0, which might be a valid address to load the kernel to. On s390 this is actually done when the kernel is not loaded via a boot loader. For kexec_file however, we cut off the first few kB of the image and jump directly to 'startup'. So checking for !0 does not cause a problem here. Anyway, the long term safer solution would be something like #define KEXEC_BUF_MEM_UNKNOWN (-1UL) for architectures to tell common code to search a fitting mem hole. Back then I didn't do the change because I had the other workaround, which didn't require a common code change. But when you are touching the code now it is worth thinking about it. Just wanted to let you know Philipp On Wed, 1 Aug 2018 16:58:07 +0900 AKASHI Takahiro wrote: > Since s390 already knows where to locate buffers, calling > arch_kexec_mem_walk() has no sense. So we can just drop it as kbuf->mem > indicates this while all other architectures sets it to 0 initially. > > This change is a preparatory work for the next patch, where all the > variant memory walks, either on system resource or memblock, will be > put in one common place so that it will satisfy all the architectures' > need. > > Signed-off-by: AKASHI Takahiro > Reviewed-by: Philipp Rudo > Cc: Martin Schwidefsky > Cc: Heiko Carstens > Cc: Dave Young > Cc: Vivek Goyal > Cc: Baoquan He > --- > arch/s390/kernel/machine_kexec_file.c | 10 ---------- > kernel/kexec_file.c | 4 ++++ > 2 files changed, 4 insertions(+), 10 deletions(-) > > diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c > index f413f57f8d20..32023b4f9dc0 100644 > --- a/arch/s390/kernel/machine_kexec_file.c > +++ b/arch/s390/kernel/machine_kexec_file.c > @@ -134,16 +134,6 @@ int kexec_file_add_initrd(struct kimage *image, struct s390_load_data *data, > return ret; > } > > -/* > - * The kernel is loaded to a fixed location. Turn off kexec_locate_mem_hole > - * and provide kbuf->mem by hand. > - */ > -int arch_kexec_walk_mem(struct kexec_buf *kbuf, > - int (*func)(struct resource *, void *)) > -{ > - return 1; > -} > - > int arch_kexec_apply_relocations_add(struct purgatory_info *pi, > Elf_Shdr *section, > const Elf_Shdr *relsec, > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 63c7ce1c0c3e..bf39df5e5bb9 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -534,6 +534,10 @@ int kexec_locate_mem_hole(struct kexec_buf *kbuf) > { > int ret; > > + /* Arch knows where to place */ > + if (kbuf->mem) > + return 0; > + > ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback); > > return ret == 1 ? 0 : -EADDRNOTAVAIL; From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1fkmWO-0002n3-27 for kexec@lists.infradead.org; Wed, 01 Aug 2018 08:30:17 +0000 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w718ThNS012489 for ; Wed, 1 Aug 2018 04:30:03 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2kk8s3sgxb-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 01 Aug 2018 04:30:03 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 1 Aug 2018 09:30:00 +0100 Date: Wed, 1 Aug 2018 10:29:51 +0200 From: Philipp Rudo Subject: Re: [PATCH v13 03/16] s390, kexec_file: drop arch_kexec_mem_walk() In-Reply-To: <20180801075820.3753-4-takahiro.akashi@linaro.org> References: <20180801075820.3753-1-takahiro.akashi@linaro.org> <20180801075820.3753-4-takahiro.akashi@linaro.org> MIME-Version: 1.0 Message-Id: <20180801102951.527cfc57@ThinkPad> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: AKASHI Takahiro Cc: herbert@gondor.apana.org.au, bhe@redhat.com, ard.biesheuvel@linaro.org, catalin.marinas@arm.com, bhsharma@redhat.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, heiko.carstens@de.ibm.com, dhowells@redhat.com, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, kexec@lists.infradead.org, schwidefsky@de.ibm.com, james.morse@arm.com, dyoung@redhat.com, davem@davemloft.net, vgoyal@redhat.com Hey Akashi, I kept thinking about this patch and remembered why I didn't made the change you are suggesting now. The problem is when you only check for kbuf->mem you are excluding address 0, which might be a valid address to load the kernel to. On s390 this is actually done when the kernel is not loaded via a boot loader. For kexec_file however, we cut off the first few kB of the image and jump directly to 'startup'. So checking for !0 does not cause a problem here. Anyway, the long term safer solution would be something like #define KEXEC_BUF_MEM_UNKNOWN (-1UL) for architectures to tell common code to search a fitting mem hole. Back then I didn't do the change because I had the other workaround, which didn't require a common code change. But when you are touching the code now it is worth thinking about it. Just wanted to let you know Philipp On Wed, 1 Aug 2018 16:58:07 +0900 AKASHI Takahiro wrote: > Since s390 already knows where to locate buffers, calling > arch_kexec_mem_walk() has no sense. So we can just drop it as kbuf->mem > indicates this while all other architectures sets it to 0 initially. > > This change is a preparatory work for the next patch, where all the > variant memory walks, either on system resource or memblock, will be > put in one common place so that it will satisfy all the architectures' > need. > > Signed-off-by: AKASHI Takahiro > Reviewed-by: Philipp Rudo > Cc: Martin Schwidefsky > Cc: Heiko Carstens > Cc: Dave Young > Cc: Vivek Goyal > Cc: Baoquan He > --- > arch/s390/kernel/machine_kexec_file.c | 10 ---------- > kernel/kexec_file.c | 4 ++++ > 2 files changed, 4 insertions(+), 10 deletions(-) > > diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c > index f413f57f8d20..32023b4f9dc0 100644 > --- a/arch/s390/kernel/machine_kexec_file.c > +++ b/arch/s390/kernel/machine_kexec_file.c > @@ -134,16 +134,6 @@ int kexec_file_add_initrd(struct kimage *image, struct s390_load_data *data, > return ret; > } > > -/* > - * The kernel is loaded to a fixed location. Turn off kexec_locate_mem_hole > - * and provide kbuf->mem by hand. > - */ > -int arch_kexec_walk_mem(struct kexec_buf *kbuf, > - int (*func)(struct resource *, void *)) > -{ > - return 1; > -} > - > int arch_kexec_apply_relocations_add(struct purgatory_info *pi, > Elf_Shdr *section, > const Elf_Shdr *relsec, > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 63c7ce1c0c3e..bf39df5e5bb9 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -534,6 +534,10 @@ int kexec_locate_mem_hole(struct kexec_buf *kbuf) > { > int ret; > > + /* Arch knows where to place */ > + if (kbuf->mem) > + return 0; > + > ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback); > > return ret == 1 ? 0 : -EADDRNOTAVAIL; _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec