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 A7D80C433EF for ; Fri, 8 Apr 2022 15:53:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237830AbiDHPzD (ORCPT ); Fri, 8 Apr 2022 11:55:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230006AbiDHPy7 (ORCPT ); Fri, 8 Apr 2022 11:54:59 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CF794D3727 for ; Fri, 8 Apr 2022 08:52:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649433173; 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=t4p+B4H/Dz0mub8FSLeM/V9Oz02JwEoHEYmciYvlkis=; b=YiA1ubv2t2Y9OpD4BArThYIxYlSUlAe9Bp4hdxHlhTeZuxCYgWfTnA2AHLXgS3el9K8f9u jlyWhiSDMM38HMmePGOLVQJ41LgTYIkdCYGaEeYeJR87p5Jza99mvp271bgptz8FBACnAa eLBRVyv8pVNBm7K6WYr8i/GIsTaAoEg= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-185-48R4cDirOfiEYVh8Ua3X5A-1; Fri, 08 Apr 2022 11:52:50 -0400 X-MC-Unique: 48R4cDirOfiEYVh8Ua3X5A-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B976F811E81; Fri, 8 Apr 2022 15:52:49 +0000 (UTC) Received: from napanee.usersys.redhat.com (ovpn-112-2.rdu2.redhat.com [10.10.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9FA29401E31; Fri, 8 Apr 2022 15:52:49 +0000 (UTC) Received: by napanee.usersys.redhat.com (Postfix, from userid 1000) id 66F87C0528; Fri, 8 Apr 2022 11:52:49 -0400 (EDT) Date: Fri, 8 Apr 2022 11:52:49 -0400 From: Aristeu Rozanski To: Lorenzo Pieralisi Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , Will Deacon , Hanjun Guo , Sudeep Holla , Catalin Marinas , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Veronika kabatova , Robin Murphy Subject: Re: [PATCH] ACPI: osl: Fix BERT error region memory mapping Message-ID: <20220408155249.mdkmdttykmoenqeu@redhat.com> References: <20220407105120.1280-1-lorenzo.pieralisi@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220407105120.1280-1-lorenzo.pieralisi@arm.com> User-Agent: NeoMutt/20211029 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 07, 2022 at 11:51:20AM +0100, Lorenzo Pieralisi wrote: > Currently the sysfs interface maps the BERT error region as "memory" > (through acpi_os_map_memory()) in order to copy the error records into > memory buffers through memory operations (eg memory_read_from_buffer()). > > The OS system cannot detect whether the BERT error region is part of > system RAM or it is "device memory" (eg BMC memory) and therefore it > cannot detect which memory attributes the bus to memory support (and > corresponding kernel mapping, unless firmware provides the required > information). > > The acpi_os_map_memory() arch backend implementation determines the > mapping attributes. On arm64, if the BERT error region is not present in > the EFI memory map, the error region is mapped as device-nGnRnE; this > triggers alignment faults since memcpy unaligned accesses are not > allowed in device-nGnRnE regions. > > The ACPI sysfs code cannot therefore map by default the BERT error > region with memory semantics but should use a safer default. > > Change the sysfs code to map the BERT error region as MMIO (through > acpi_os_map_iomem()) and use the memcpy_fromio() interface to read the > error region into the kernel buffer. > > Link: https://lore.kernel.org/linux-arm-kernel/31ffe8fc-f5ee-2858-26c5-0fd8bdd68702@arm.com > Link: https://lore.kernel.org/linux-acpi/CAJZ5v0g+OVbhuUUDrLUCfX_mVqY_e8ubgLTU98=jfjTeb4t+Pw@mail.gmail.com > Signed-off-by: Lorenzo Pieralisi > Cc: Ard Biesheuvel > Cc: Will Deacon > Cc: Hanjun Guo > Cc: Sudeep Holla > Cc: Catalin Marinas > Cc: "Rafael J. Wysocki" > --- > drivers/acpi/sysfs.c | 25 ++++++++++++++++++------- > 1 file changed, 18 insertions(+), 7 deletions(-) > > diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c > index a4b638bea6f1..cc2fe0618178 100644 > --- a/drivers/acpi/sysfs.c > +++ b/drivers/acpi/sysfs.c > @@ -415,19 +415,30 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj, > loff_t offset, size_t count) > { > struct acpi_data_attr *data_attr; > - void *base; > - ssize_t rc; > + void __iomem *base; > + ssize_t size; > > data_attr = container_of(bin_attr, struct acpi_data_attr, attr); > + size = data_attr->attr.size; > + > + if (offset < 0) > + return -EINVAL; > + > + if (offset >= size) > + return 0; > > - base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size); > + if (count > size - offset) > + count = size - offset; > + > + base = acpi_os_map_iomem(data_attr->addr, size); > if (!base) > return -ENOMEM; > - rc = memory_read_from_buffer(buf, count, &offset, base, > - data_attr->attr.size); > - acpi_os_unmap_memory(base, data_attr->attr.size); > > - return rc; > + memcpy_fromio(buf, base + offset, count); > + > + acpi_os_unmap_iomem(base, size); > + > + return count; > } > > static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr) I've tested this patch with the reproducer and I was unable to reproduce the issue. Tested-by: Aristeu Rozanski -- Aristeu