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=-14.8 required=3.0 tests=DKIMWL_WL_HIGH,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, 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 3F028C432C3 for ; Thu, 28 Nov 2019 20:24:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12870217D9 for ; Thu, 28 Nov 2019 20:24:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eRTnt98S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726664AbfK1UYE (ORCPT ); Thu, 28 Nov 2019 15:24:04 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:53200 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726565AbfK1UYE (ORCPT ); Thu, 28 Nov 2019 15:24:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574972643; 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=eRTnt98SeiFEeIXZOpvSQqxeCPtCgMCbF4JTYVbJ1+SUSx/GhR5FBwzuyhtGSDmtp9Iw4t 7vF+Q1MqBAdjVmS5cNDZhxhIGabzDJkwGYF/beiPn0YAn3ynpXffWSZhlv4M7yMg2yZTj5 EMLPOixAbAFruTxJtU+qSkNE9mZzghg= Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-285-8OaPkrwlM5aFse7UOhO_6A-1; Thu, 28 Nov 2019 15:24:02 -0500 Received: by mail-pl1-f198.google.com with SMTP id q14so11718563plr.15 for ; Thu, 28 Nov 2019 12:24:02 -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=JZR+WYc+Yux3LQTs6jKD2Y9/+nvU239pZTBdhJDB0oalPxt5b4RZCUadBnqjwqvFG3 GWLNwcTHa7meuzVBPrC39Q2NJVvdPQnX8JYV+FyuFARS9q/s2wtzc2wPC/0VY2SqCxJd m5oo+SPxFdDd/66fCQVUIhgAm05DOq5ED+T76Cxc2gK3MhkhFpkrIPr4KUJzyWjdi20V rAVCagmiUO/Zf/68wV8kIy5n1jxpTNhQgzKx1K9KfaFNM0EreUD1RxeXIwmpUPS1STyQ DbrpRSc8oJ9DslWwxRbDMCTprUheeatHxkfNI5Cnlnymf73BTSHS5AFXQpiVhsjU0z8E Ym2g== X-Gm-Message-State: APjAAAWflXQBNt9nlRfmNUFjkOnkXP1Bb186HASrsLDNyy0UiOUw/9C+ +cPRnM5oFEIVBVuarjOV2H9CJbdbtAIiveTwAZmkphKmt2/AsY/Y2mrTRPbyrE42WRmcL6XO2lK dV/ut4u3mMFG5jrfDFXcu X-Received: by 2002:a17:90a:3663:: with SMTP id s90mr14556241pjb.1.1574972639253; Thu, 28 Nov 2019 12:23:59 -0800 (PST) X-Google-Smtp-Source: APXvYqwEBnny8bOGZ2sOhQL9nLkTVF0UqIXllrctdH9WVSgwdhpBSy3J7AMOGgxRJJki+CNRMtBZ+Q== X-Received: by 2002:a17:90a:3663:: with SMTP id s90mr14556206pjb.1.1574972638976; Thu, 28 Nov 2019 12:23:58 -0800 (PST) Received: from localhost ([122.177.85.74]) by smtp.gmail.com with ESMTPSA id s66sm22322578pfb.38.2019.11.28.12.23.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Nov 2019 12:23:58 -0800 (PST) From: Bhupesh Sharma To: linux-kernel@vger.kernel.org Cc: bhsharma@redhat.com, bhupesh.linux@gmail.com, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kexec@lists.infradead.org, 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 Subject: [PATCH v5 1/5] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo Date: Fri, 29 Nov 2019 01:53:37 +0530 Message-Id: <1574972621-25750-2-git-send-email-bhsharma@redhat.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1574972621-25750-1-git-send-email-bhsharma@redhat.com> References: <1574972621-25750-1-git-send-email-bhsharma@redhat.com> X-MC-Unique: 8OaPkrwlM5aFse7UOhO_6A-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@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