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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 BFD22C433DF for ; Wed, 13 May 2020 18:52:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 661CD2065C for ; Wed, 13 May 2020 18:52:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XNKC5K6G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390294AbgEMSww (ORCPT ); Wed, 13 May 2020 14:52:52 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:57671 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2390263AbgEMSwt (ORCPT ); Wed, 13 May 2020 14:52:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589395967; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=wHSBbB5/QZT/EwoeOOweY77s6h/009zkbzY0iSlBYP8=; b=XNKC5K6G/mfo8AKKLTtuLBsXi/K+dlZeEVFIiRACByhsrnRXasb7YTzsY1V4W2ugxgU08z xJy3I8u4dE9fdEMh5VjEqzqJ+Amm7uMgWU5XazNwhZIw9ioxd3Jk3dLu4UCt0ekk3yhBt7 FvyuNjMCYscxLr3EACtDbHkKCbTBYzM= Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-235-65YgdnZGO9CHMQl_Qezs1A-1; Wed, 13 May 2020 14:52:46 -0400 X-MC-Unique: 65YgdnZGO9CHMQl_Qezs1A-1 Received: by mail-pg1-f199.google.com with SMTP id y4so321187pgo.6 for ; Wed, 13 May 2020 11:52:45 -0700 (PDT) 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=wHSBbB5/QZT/EwoeOOweY77s6h/009zkbzY0iSlBYP8=; b=EtFhrkcOPrkYkVd0KC05aF4a4fk21lUAZAJDGu8Z2u5k1UBRGFfjE1Emap62L7vbwU CuHoQZ/phCIn0j7YXWuTVLpNWoNUJw52SNNEMJAiFOIyQnbKlR1OurrxEboYLvjx8bVl SLIFLAInoIOA/m7s59wPOoVaVkvZsOUl0ZefhEHHRcMPpcTsjrjb+sqEgfJ3J6FMYARi Zm0zHGifD261UXtn5rH6LjSxHQPsyKAsMXDimOwC3i3PltRmmL9xOCBDZ8pt3webeai4 Q8L6ca8RKSF9CEYrf0acLX775DNmjbP9E6bTaDfR9mb9poBMqrdOKhFhSAyN+FyfSx2E YZcQ== X-Gm-Message-State: AOAM530isrOT7gjF5s5I0tbMD4PFuBfZXL4OHKTGDLsX48fc21OuPlYD woZtgkXErL29JJQspIYlKjbM+mHxmuXdtnnvXtjvQRUoiK//jrTpFWHUG48/8X7x6jhf2BdY2uP z/m9FSTDQlkrSyV5BESwCVfMg X-Received: by 2002:aa7:82d4:: with SMTP id f20mr638950pfn.253.1589395964832; Wed, 13 May 2020 11:52:44 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz5Sglv3QSN2AQ8L8vX+EbHi2Jv4mN3LxBZJj8ZVFGF26HEK+cSiLoq/r1EcEne4FxQ9u0lwQ== X-Received: by 2002:aa7:82d4:: with SMTP id f20mr638933pfn.253.1589395964561; Wed, 13 May 2020 11:52:44 -0700 (PDT) Received: from localhost ([122.177.166.225]) by smtp.gmail.com with ESMTPSA id d2sm230168pfa.164.2020.05.13.11.52.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 May 2020 11:52:43 -0700 (PDT) From: Bhupesh Sharma To: linux-arm-kernel@lists.infradead.org, x86@kernel.org Cc: bhsharma@redhat.com, bhupesh.linux@gmail.com, Boris Petkov , Ingo Molnar , Thomas Gleixner , James Morse , Mark Rutland , Will Deacon , Michael Ellerman , Paul Mackerras , Benjamin Herrenschmidt , Dave Anderson , Kazuhito Hagio , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org Subject: [PATCH v6 1/2] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo Date: Thu, 14 May 2020 00:22:36 +0530 Message-Id: <1589395957-24628-2-git-send-email-bhsharma@redhat.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1589395957-24628-1-git-send-email-bhsharma@redhat.com> References: <1589395957-24628-1-git-send-email-bhsharma@redhat.com> 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: While at it also update vmcoreinfo documentation for 'MAX_PHYSMEM_BITS' variable being added to vmcoreinfo. 'MAX_PHYSMEM_BITS' defines the maximum supported physical address space memory. Cc: Boris Petkov Cc: Ingo Molnar Cc: Thomas Gleixner Cc: James Morse Cc: Mark Rutland Cc: Will Deacon 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 Tested-by: John Donnelly Signed-off-by: Bhupesh Sharma --- Documentation/admin-guide/kdump/vmcoreinfo.rst | 5 +++++ kernel/crash_core.c | 1 + 2 files changed, 6 insertions(+) diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst index e4ee8b2db604..2a632020f809 100644 --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst @@ -93,6 +93,11 @@ It exists in the sparse memory mapping model, and it is also somewhat similar to the mem_map variable, both of them are used to translate an address. +MAX_PHYSMEM_BITS +---------------- + +Defines the maximum supported physical address space memory. + page ---- 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) VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); VMCOREINFO_STRUCT_SIZE(mem_section); VMCOREINFO_OFFSET(mem_section, section_mem_map); + VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); #endif VMCOREINFO_STRUCT_SIZE(page); VMCOREINFO_STRUCT_SIZE(pglist_data); -- 2.7.4