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=-14.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 BC93DC43381 for ; Wed, 20 Mar 2019 05:13:10 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 41E642175B for ; Wed, 20 Mar 2019 05:13:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41E642175B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44PJ380PrmzDqJs for ; Wed, 20 Mar 2019 16:13:08 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=redhat.com (client-ip=209.85.210.193; helo=mail-pf1-f193.google.com; envelope-from=bhsharma@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Received: from mail-pf1-f193.google.com (mail-pf1-f193.google.com [209.85.210.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44PHzP4RNszDqCg for ; Wed, 20 Mar 2019 16:09:52 +1100 (AEDT) Received: by mail-pf1-f193.google.com with SMTP id i17so1021042pfo.6 for ; Tue, 19 Mar 2019 22:09:52 -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=e4gf7gQQRDrHYkHmBGmiy/271ro0jZqvmttHmTXDjOw=; b=W7X7jnvudc+Z41o1Jn9xd/1R+ApkEEmAbo+rJY8X+P8wR4E12IeJOxAqusimXMIE3K xEYjiKoXWwCqC/uNZpNgsL8hSE3KVaJnLSFbcpuLNjUEc7RSKWTyvpXc5BNjFxRqyZ7t WSUN2YdXZNWErtz19QUJyH4cxwyYlUACSpOsRVIO1Gq6lg+BQZxQSeBjJDhQ8jmRsBxZ Igf6aAubVoGAsGkuABIDDwnumZhYXkFtB50P5/phWNSAxtbVj9TjFk9Dbb4A0+WDI2SK suxPqOfXSPiVzf0hfXV7aGsdIAw0aPjVq1qsbqvJ7oJyylQWEvVuEzPaNyzktvV0Ue97 Pv8A== X-Gm-Message-State: APjAAAU7InmNhOWtyiTSud+q7wYhHRAF8wWnjSfb52KfWqITmKyzpGRC ceO14F1CHrqAwQKeOKgPCqeNNg== X-Google-Smtp-Source: APXvYqwquzJ/LobGlm7cNilKJM6zRdniDHacYy1BqPtGwxNdqRtts7VAQpU4ybvYWD6CVPzQvfam4A== X-Received: by 2002:a63:e002:: with SMTP id e2mr5901612pgh.300.1553058590559; Tue, 19 Mar 2019 22:09:50 -0700 (PDT) Received: from localhost ([122.177.144.121]) by smtp.gmail.com with ESMTPSA id e123sm958508pfe.35.2019.03.19.22.09.48 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Mar 2019 22:09:49 -0700 (PDT) From: Bhupesh Sharma To: linux-kernel@vger.kernel.org Subject: [PATCH v3 2/3] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo Date: Wed, 20 Mar 2019 10:39:33 +0530 Message-Id: <1553058574-18606-3-git-send-email-bhsharma@redhat.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1553058574-18606-1-git-send-email-bhsharma@redhat.com> References: <1553058574-18606-1-git-send-email-bhsharma@redhat.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kazuhito Hagio , bhsharma@redhat.com, x86@kernel.org, Will Deacon , linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, James Morse , linux-arm-kernel@lists.infradead.org, Boris Petkov , Thomas Gleixner , bhupesh.linux@gmail.com, Dave Anderson , Ingo Molnar , Paul Mackerras Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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-mem-bit-v1/arch/ppc64.c#L471 Cc: Boris Petkov Cc: Ingo Molnar Cc: Thomas Gleixner Cc: James Morse 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 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 093c9f917ed0..495f09084696 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -415,6 +415,7 @@ 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