From patchwork Tue Nov 24 22:25:34 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geoff Levand X-Patchwork-Id: 7694371 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id C52389F443 for ; Tue, 24 Nov 2015 22:57:46 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BD3DB207DB for ; Tue, 24 Nov 2015 22:57:45 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A14712077E for ; Tue, 24 Nov 2015 22:57:44 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a1MVF-0005lv-6Z; Tue, 24 Nov 2015 22:56:01 +0000 Received: from merlin.infradead.org ([2001:4978:20e::2]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a1MU3-00045n-AJ; Tue, 24 Nov 2015 22:54:47 +0000 Received: from geoff by merlin.infradead.org with local (Exim 4.85 #2 (Red Hat Linux)) id 1a1M1m-0007XE-DK; Tue, 24 Nov 2015 22:25:34 +0000 Message-Id: <8b02b030a4a081816f35e49b210b41d9f6e2d961.1448403503.git.geoff@infradead.org> In-Reply-To: References: From: Geoff Levand Patch-Date: Wed, 19 Aug 2015 16:43:42 +0900 Subject: [PATCH v12 13/16] arm64: kdump: add kdump support To: Catalin Marinas , Will Deacon Date: Tue, 24 Nov 2015 22:25:34 +0000 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , marc.zyngier@arm.com, kexec@lists.infradead.org, AKASHI Takahiro , christoffer.dall@linaro.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.8 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: AKASHI Takahiro On crash dump kernel, all the information about primary kernel's core image is available in elf core header specified by "elfcorehdr=" boot parameter. reserve_elfcorehdr() will set aside the region to avoid any corruption by crash dump kernel. Crash dump kernel will access the system memory of primary kernel via copy_oldmem_page(), which reads one page by ioremap'ing it since it does not reside in linear mapping on crash dump kernel. Please note that we should add "mem=X[MG]" boot parameter to limit the memory size and avoid the following assertion at ioremap(): if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr)))) return NULL; when accessing any pages beyond the usable memories of crash dump kernel. We also need our own elfcorehdr_read() here since the weak definition of elfcorehdr_read() utilizes copy_oldmem_page() and will hit the assertion above on arm64. Signed-off-by: AKASHI Takahiro --- arch/arm64/Kconfig | 12 +++++++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/crash_dump.c | 71 ++++++++++++++++++++++++++++++++++++++++++ arch/arm64/mm/init.c | 29 +++++++++++++++++ 4 files changed, 113 insertions(+) create mode 100644 arch/arm64/kernel/crash_dump.c diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index c23fd77..4bac7dc 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -545,6 +545,18 @@ config KEXEC but it is independent of the system firmware. And like a reboot you can start any kernel with it, not just Linux. +config CRASH_DUMP + bool "Build kdump crash kernel" + help + Generate crash dump after being started by kexec. This should + be normally only set in special crash dump kernels which are + loaded in the main kernel with kexec-tools into a specially + reserved region and then later executed after a crash by + kdump/kexec. The crash dump kernel must be compiled to a + memory address not used by the main kernel. + + For more details see Documentation/kdump/kdump.txt + config XEN_DOM0 def_bool y depends on XEN diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index f68420d..a08b054 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -43,6 +43,7 @@ arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o arm64-obj-$(CONFIG_ACPI) += acpi.o arm64-obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o \ cpu-reset.o +arm64-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-y += $(arm64-obj-y) vdso/ obj-m += $(arm64-obj-m) diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c new file mode 100644 index 0000000..3d86c0a --- /dev/null +++ b/arch/arm64/kernel/crash_dump.c @@ -0,0 +1,71 @@ +/* + * Routines for doing kexec-based kdump + * + * Copyright (C) 2014 Linaro Limited + * Author: AKASHI Takahiro + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include + +/** + * copy_oldmem_page() - copy one page from old kernel memory + * @pfn: page frame number to be copied + * @buf: buffer where the copied page is placed + * @csize: number of bytes to copy + * @offset: offset in bytes into the page + * @userbuf: if set, @buf is in a user address space + * + * This function copies one page from old kernel memory into buffer pointed by + * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes + * copied or negative error in case of failure. + */ +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 = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE); + if (!vaddr) + return -ENOMEM; + + if (userbuf) { + if (copy_to_user(buf, vaddr + offset, csize)) { + iounmap(vaddr); + return -EFAULT; + } + } else { + memcpy(buf, vaddr + offset, csize); + } + + iounmap(vaddr); + + return csize; +} + +/** + * elfcorehdr_read - read from ELF core header + * @buf: buffer where the data is placed + * @csize: number of bytes to read + * @ppos: address in the memory + * + * This function reads @count bytes from elf core header which exists + * on crash dump kernel's memory. + */ +ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) +{ + memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count); + return count; +} diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 24f0a1c..52a1469 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include @@ -116,6 +117,31 @@ static void __init reserve_crashkernel(void) } #endif /* CONFIG_KEXEC */ +#ifdef CONFIG_CRASH_DUMP +/* + * reserve_elfcorehdr() - reserves memory for elf core header + * + * This function reserves elf core header given in "elfcorehdr=" kernel + * command line parameter. This region contains all the information about + * primary kernel's core image and is used by a dump capture kernel to + * access the system memory on primary kernel. + */ +static void __init reserve_elfcorehdr(void) +{ + if (!elfcorehdr_size) + return; + + if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) { + pr_warn("elfcorehdr is overlapped\n"); + return; + } + + memblock_reserve(elfcorehdr_addr, elfcorehdr_size); + + pr_info("Reserving %lldKB of memory at %lldMB for elfcorehdr\n", + elfcorehdr_size >> 10, elfcorehdr_addr >> 20); +} +#endif /* CONFIG_CRASH_DUMP */ /* * Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It * currently assumes that for memory starting above 4G, 32-bit devices will @@ -224,6 +250,9 @@ void __init arm64_memblock_init(void) #ifdef CONFIG_KEXEC reserve_crashkernel(); #endif +#ifdef CONFIG_CRASH_DUMP + reserve_elfcorehdr(); +#endif early_init_fdt_scan_reserved_mem();