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=-14.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 E083CC43331 for ; Mon, 11 Nov 2019 08:01:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC4982075C for ; Mon, 11 Nov 2019 08:01:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DUu2/kvZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726991AbfKKIBt (ORCPT ); Mon, 11 Nov 2019 03:01:49 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:41413 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726978AbfKKIBt (ORCPT ); Mon, 11 Nov 2019 03:01:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1573459307; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/y8p7TWJ4+9dx0qZYntYI0vqqca78jHSFlqFEn+6Y9I=; b=DUu2/kvZEmOvof4/tNV1rY+CmIG+onkYRpmW/YoL5wM0wE/UHKoU4I2JIexa5kSXs6k3wI vohzwLE6eRERY21Evf5pbpSMuaScSHB6aECxKqgts17sps4gRUrch21sElvlTPxMEH/onZ I+MsxkWGBK6btT1yx2xWhd8Uly1hfQQ= Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-232-hDHuI4ayN9uwvkCSqtPvPg-1; Mon, 11 Nov 2019 03:01:46 -0500 Received: by mail-pf1-f199.google.com with SMTP id j2so12040802pfa.8 for ; Mon, 11 Nov 2019 00:01:46 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=D7Q1sNAJK7KGCeC1/osi4u/yd8LMbojW2DcAg7eyhwk=; b=QBQpxemsr+wzaa7prbvECzSe9a7nk7vpAzo2OcwZyDH34c53OuQE6Yx1DAVtNORNEc QjtV0neCOBtKXFenKPLJZCajhgHr6Ve3lbvno+Jq2VUe2CLwy/y28PQiV4a0kWPa/aVx ZQCc/rpyWxTHQrZx4StgfwSnPaZnHiyBvvClnMgEz4w/2TB+OQZXS92gxNWdEHOPkGwW KRC/PgY7qKfxIduT2RakRm6QLK6KSbNYyAYv+7jPWtg+5BP2q7zxo6VQGfNj4/fijlK8 UFKQGEP9QXBH8g9ivbFSbYdKmaQRtjGMKBvYt6aDLgDHLXKqYudjFKdLongAKxo5j5Cu rnAA== X-Gm-Message-State: APjAAAWNYKg2l5KCRFk3XzDSMQmucwEx81uoJ3sDwNzysmmsdQ4gVyfb dwmWSWGrw69/rbhHswidkWXMXjnZv6qfsfLe+5FHXgb/NWy47Hk+oLrD+NlNuqME6SM+6kpxLW3 djzC8UPLPW21gYdwW4NzGEOe1 X-Received: by 2002:a62:fcd2:: with SMTP id e201mr404509pfh.52.1573459301444; Mon, 11 Nov 2019 00:01:41 -0800 (PST) X-Google-Smtp-Source: APXvYqw/PM/uE1YEEDp1OQcYhDW64ur/c96jF9ficCBtta087Mx43bjXxmhjovhzV8sTDdZdS3kXpw== X-Received: by 2002:a62:fcd2:: with SMTP id e201mr404459pfh.52.1573459301055; Mon, 11 Nov 2019 00:01:41 -0800 (PST) Received: from localhost ([122.177.0.15]) by smtp.gmail.com with ESMTPSA id r33sm12736180pjb.5.2019.11.11.00.01.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 11 Nov 2019 00:01:39 -0800 (PST) From: Bhupesh Sharma To: linux-kernel@vger.kernel.org Cc: bhsharma@redhat.com, bhupesh.linux@gmail.com, Boris Petkov , Ingo Molnar , Thomas Gleixner , James Morse , Mark Rutland , Will Deacon , Steve Capper , Catalin Marinas , Ard Biesheuvel , Michael Ellerman , Paul Mackerras , Benjamin Herrenschmidt , Dave Anderson , Kazuhito Hagio , x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, kexec@lists.infradead.org Subject: [PATCH v4 1/3] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo Date: Mon, 11 Nov 2019 13:31:20 +0530 Message-Id: <1573459282-26989-2-git-send-email-bhsharma@redhat.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1573459282-26989-1-git-send-email-bhsharma@redhat.com> References: <1573459282-26989-1-git-send-email-bhsharma@redhat.com> X-MC-Unique: hDHuI4ayN9uwvkCSqtPvPg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Right now user-space tools like 'makedumpfile' and 'crash' need to rely on a best-guess method of determining value of 'MAX_PHYSMEM_BITS' supported by underlying kernel. This value is used in user-space code to calculate the bit-space required to store a section for SPARESMEM (similar to the existing calculation method used in the kernel implementation): #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) Now, regressions have been reported in user-space utilities like 'makedumpfile' and 'crash' on arm64, with the recently added kernel support for 52-bit physical address space, as there is no clear method of determining this value in user-space (other than reading kernel CONFIG flags). As per suggestion from makedumpfile maintainer (Kazu), it makes more sense to append 'MAX_PHYSMEM_BITS' to vmcoreinfo in the core code itself rather than in arch-specific code, so that the user-space code for other archs can also benefit from this addition to the vmcoreinfo and use it as a standard way of determining 'SECTIONS_SHIFT' value in user-land. A reference 'makedumpfile' implementation which reads the 'MAX_PHYSMEM_BITS' value from vmcoreinfo in a arch-independent fashion is available here: [0]. https://github.com/bhupesh-sharma/makedumpfile/blob/remove-max-phys-me= m-bit-v1/arch/ppc64.c#L471 Cc: Boris Petkov Cc: Ingo Molnar Cc: Thomas Gleixner Cc: James Morse Cc: Mark Rutland Cc: Will Deacon Cc: Steve Capper Cc: Catalin Marinas Cc: Ard Biesheuvel Cc: Michael Ellerman Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Dave Anderson Cc: Kazuhito Hagio Cc: x86@kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: kexec@lists.infradead.org Signed-off-by: Bhupesh Sharma --- kernel/crash_core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 9f1557b98468..18175687133a 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -413,6 +413,7 @@ static int __init crash_save_vmcoreinfo_init(void) =09VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); =09VMCOREINFO_STRUCT_SIZE(mem_section); =09VMCOREINFO_OFFSET(mem_section, section_mem_map); +=09VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); #endif =09VMCOREINFO_STRUCT_SIZE(page); =09VMCOREINFO_STRUCT_SIZE(pglist_data); --=20 2.7.4