From patchwork Tue Nov 3 09:27:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 11876891 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2F6071130 for ; Tue, 3 Nov 2020 10:35:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 05E552242A for ; Tue, 3 Nov 2020 10:35:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="jlx8Ex5H"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="dVvfT1Tw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728701AbgKCKfa (ORCPT ); Tue, 3 Nov 2020 05:35:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728513AbgKCKeE (ORCPT ); Tue, 3 Nov 2020 05:34:04 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A24FC0613D1; Tue, 3 Nov 2020 02:34:04 -0800 (PST) Message-Id: <20201103095859.429620021@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1604399637; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=K8tv6h9J8+1UjPWtbytb7n5SLceTF9zssV9oZox9W+U=; b=jlx8Ex5HCWlxXvrnli8/QwvyuSFPzsuFrOckZnFstrBk6aYnaxCTE/6eIpzUyy3HTFA9dN j2MhhyK0rzrnVOQ277ubDpOdBu8/ePvDTWcYkFn67cFtyw9jv6pUAD7YSvQ2mlOaf0dtF/ pHfOJ4qnMNrsWT5Blx8qbKTjW4qwZRparaSaimAWnAEl7Ugw1vjOoGWZEEMX6/kMY4xvm4 Run48zgUaP3VverUvyAteqfjoP06jefJKul2RFnRd4pDzuc3AmboC5oIeMYQGIVL4MQT1u v0/E2lNjgVb2i25uzJEr9A1NWYgTnWrFPcuC8jA8qwqSrF/+ReNLpCdWbCjAfg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604399637; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=K8tv6h9J8+1UjPWtbytb7n5SLceTF9zssV9oZox9W+U=; b=dVvfT1TwOkonT78xNAJPVdoIKohkvh+HLW+i9zfm8hjJfQ/wzEekIVlHbnLgxURHEJHa93 KSDbl/WiRJPwtbCA== Date: Tue, 03 Nov 2020 10:27:40 +0100 From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Peter Zijlstra , Paul McKenney , Christoph Hellwig , Sebastian Andrzej Siewior , Thomas Bogendoerfer , linux-mips@vger.kernel.org, Andrew Morton , linux-mm@kvack.org, Alexander Viro , Benjamin LaHaise , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, x86@kernel.org, Vineet Gupta , linux-snps-arc@lists.infradead.org, Russell King , Arnd Bergmann , linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, Michal Simek , Nick Hu , Greentime Hu , Vincent Chen , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, "David S. Miller" , sparclinux@vger.kernel.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Christian Koenig , Huang Rui , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, VMware Graphics , Roland Scheidegger , Dave Airlie , Gerd Hoffmann , virtualization@lists.linux-foundation.org, spice-devel@lists.freedesktop.org, Ben Skeggs , nouveau@lists.freedesktop.org, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , intel-gfx@lists.freedesktop.org Subject: [patch V3 28/37] mips/crashdump: Simplify copy_oldmem_page() References: <20201103092712.714480842@linutronix.de> MIME-Version: 1.0 Content-transfer-encoding: 8-bit Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Replace kmap_atomic_pfn() with kmap_local_pfn() which is preemptible and can take page faults. Remove the indirection of the dump page and the related cruft which is not longer required. Signed-off-by: Thomas Gleixner Cc: Thomas Bogendoerfer Cc: linux-mips@vger.kernel.org --- V3: New patch --- arch/mips/kernel/crash_dump.c | 42 +++++++----------------------------------- 1 file changed, 7 insertions(+), 35 deletions(-) --- a/arch/mips/kernel/crash_dump.c +++ b/arch/mips/kernel/crash_dump.c @@ -5,8 +5,6 @@ #include #include -static void *kdump_buf_page; - /** * copy_oldmem_page - copy one page from "oldmem" * @pfn: page frame number to be copied @@ -17,51 +15,25 @@ static void *kdump_buf_page; * @userbuf: if set, @buf is in user address space, use copy_to_user(), * otherwise @buf is in kernel address space, use memcpy(). * - * Copy a page from "oldmem". For this page, there is no pte mapped + * Copy a page from "oldmem". For this page, there might be no pte mapped * in the current kernel. - * - * Calling copy_to_user() in atomic context is not desirable. Hence first - * copying the data to a pre-allocated kernel page and then copying to user - * space in non-atomic context. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, + unsigned long offset, int userbuf) { void *vaddr; if (!csize) return 0; - vaddr = kmap_atomic_pfn(pfn); + vaddr = kmap_local_pfn(pfn); if (!userbuf) { - memcpy(buf, (vaddr + offset), csize); - kunmap_atomic(vaddr); + memcpy(buf, vaddr + offset, csize); } else { - if (!kdump_buf_page) { - pr_warn("Kdump: Kdump buffer page not allocated\n"); - - return -EFAULT; - } - copy_page(kdump_buf_page, vaddr); - kunmap_atomic(vaddr); - if (copy_to_user(buf, (kdump_buf_page + offset), csize)) - return -EFAULT; + if (copy_to_user(buf, vaddr + offset, csize)) + csize = -EFAULT; } return csize; } - -static int __init kdump_buf_page_init(void) -{ - int ret = 0; - - kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!kdump_buf_page) { - pr_warn("Kdump: Failed to allocate kdump buffer page\n"); - ret = -ENOMEM; - } - - return ret; -} -arch_initcall(kdump_buf_page_init);