From patchwork Tue Nov 3 09:27:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 11876951 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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 D1478C8262D for ; Tue, 3 Nov 2020 10:34:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 834FD22409 for ; Tue, 3 Nov 2020 10:34:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="EFq00YaC"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="MNJFQ16T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728485AbgKCKeJ (ORCPT ); Tue, 3 Nov 2020 05:34:09 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:39508 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728495AbgKCKeC (ORCPT ); Tue, 3 Nov 2020 05:34:02 -0500 Message-Id: <20201103095859.335366302@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1604399636; 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=A9fIQi2MIxDLlGKHATeOlK6WSHzl9bMxA6Vy6WK4kFg=; b=EFq00YaC2cfZ3tRBXG1AYeQj6Sgd3q/sRky5nMpbjN5ek1aWLKVPUv+JvoHWa6vjJFl3Ww awzO+FzbND5FKjPGN7gNTnp5Mb1tq9qO15q652V8S0pc9Ce+oaGECW/jZPsmCvsiKGY+B3 KwlcTL/aSMXp1KJx2nFOb6gxG+DhM4n5p7kt5iTVZXpFOkBEw1cbStLJ+/3gWYcjPH26QY Sbv7PLzlBaetuHp8ai5dMyYUIWrRveb5P6ybl5UfTZhOpH3MacNEiFaKtx28E2gAmPiYft OZoB88IwwamuMjukOjyOm6rKIPayv2itPmrCw7QTvAcv81mGKSLdYHUqSDcl3Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604399636; 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=A9fIQi2MIxDLlGKHATeOlK6WSHzl9bMxA6Vy6WK4kFg=; b=MNJFQ16TWMWokWTa10gHMVVbsQOpiB2QfbpOViNefBGxmMK6yL/K8NxBWEF2+7F4dQI9lX SBoVS11NJaJ9FoCQ== Date: Tue, 03 Nov 2020 10:27:39 +0100 From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Peter Zijlstra , Paul McKenney , Christoph Hellwig , Sebastian Andrzej Siewior , 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 , Thomas Bogendoerfer , linux-mips@vger.kernel.org, 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 27/37] x86/crashdump/32: 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-btrfs@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 --- V3: New patch --- arch/x86/kernel/crash_dump_32.c | 48 ++++++++-------------------------------- 1 file changed, 10 insertions(+), 38 deletions(-) --- a/arch/x86/kernel/crash_dump_32.c +++ b/arch/x86/kernel/crash_dump_32.c @@ -13,8 +13,6 @@ #include -static void *kdump_buf_page; - static inline bool is_crashed_pfn_valid(unsigned long pfn) { #ifndef CONFIG_X86_PAE @@ -41,15 +39,11 @@ static inline bool is_crashed_pfn_valid( * @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 - * in the current kernel. We stitch up a pte, similar to kmap_atomic. - * - * 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. + * Copy a page from "oldmem". For this page, there might be no pte mapped + * in the current kernel. */ -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; @@ -59,38 +53,16 @@ ssize_t copy_oldmem_page(unsigned long p if (!is_crashed_pfn_valid(pfn)) return -EFAULT; - 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) { - printk(KERN_WARNING "Kdump: Kdump buffer page not" - " allocated\n"); - kunmap_atomic(vaddr); - 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; -} + kunmap_local(vaddr); -static int __init kdump_buf_page_init(void) -{ - int ret = 0; - - kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!kdump_buf_page) { - printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer" - " page\n"); - ret = -ENOMEM; - } - - return ret; + return csize; } -arch_initcall(kdump_buf_page_init);