From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760551AbcBYN7H (ORCPT ); Thu, 25 Feb 2016 08:59:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47097 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760194AbcBYN7E (ORCPT ); Thu, 25 Feb 2016 08:59:04 -0500 From: Minfei Huang To: ebiederm@xmission.com, akpm@linux-foundation.org Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, mhuang@redhat.com, Minfei Huang Subject: [PATCH] kexec: Make a pair of map/unmap reserved pages in error path Date: Thu, 25 Feb 2016 22:02:40 +0800 Message-Id: <1456408960-12296-1-git-send-email-mhuang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Minfei Huang For some arch, kexec shall map the reserved pages, then use them, when we try to start the kdump service. kexec may return directly, without unmaping the reserved pages, if it fails during starting service. To fix it, we make a pair of map/unmap reserved pages both in generic path and error path. Signed-off-by: Minfei Huang --- kernel/kexec.c | 112 ++++++++++++++++++++++++++++++++------------------------- 1 file changed, 63 insertions(+), 49 deletions(-) diff --git a/kernel/kexec.c b/kernel/kexec.c index ee70aef..48cf69c 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -103,6 +103,68 @@ out_free_image: return ret; } +static int do_kexec_load(unsigned long entry, unsigned long nr_segments, + struct kexec_segment __user *segments, unsigned long flags) +{ + struct kimage **dest_image, *image; + unsigned long i; + int ret; + + if (flags & KEXEC_ON_CRASH) + dest_image = &kexec_crash_image; + else + dest_image = &kexec_image; + + if (nr_segments == 0) { + /* Uninstall image */ + kimage_free(xchg(dest_image, NULL)); + return 0; + } + if (flags & KEXEC_ON_CRASH) { + /* + * Loading another kernel to switch to if this one + * crashes. Free any current crash dump kernel before + * we corrupt it. + */ + kimage_free(xchg(&kexec_crash_image, NULL)); + } + + ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags); + if (ret) + return ret; + + if (flags & KEXEC_ON_CRASH) + crash_map_reserved_pages(); + + if (flags & KEXEC_PRESERVE_CONTEXT) + image->preserve_context = 1; + + ret = machine_kexec_prepare(image); + if (ret) + goto out; + + for (i = 0; i < nr_segments; i++) { + ret = kimage_load_segment(image, &image->segment[i]); + if (ret) + goto out; + } + + kimage_terminate(image); + + /* Install the new kernel and uninstall the old */ + image = xchg(dest_image, image); + +out: + /* + * Once the reserved memory is mapped, we should unmap this memory + * before returning + */ + if (flags & KEXEC_ON_CRASH) + crash_unmap_reserved_pages(); + kimage_free(image); + return ret; +} + /* * Exec Kernel system call: for obvious reasons only root may call it. * @@ -127,7 +189,6 @@ out_free_image: SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, struct kexec_segment __user *, segments, unsigned long, flags) { - struct kimage **dest_image, *image; int result; /* We only trust the superuser with rebooting the system. */ @@ -152,9 +213,6 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, if (nr_segments > KEXEC_SEGMENT_MAX) return -EINVAL; - image = NULL; - result = 0; - /* Because we write directly to the reserved memory * region when loading crash kernels we need a mutex here to * prevent multiple crash kernels from attempting to load @@ -166,53 +224,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, if (!mutex_trylock(&kexec_mutex)) return -EBUSY; - dest_image = &kexec_image; - if (flags & KEXEC_ON_CRASH) - dest_image = &kexec_crash_image; - if (nr_segments > 0) { - unsigned long i; - - if (flags & KEXEC_ON_CRASH) { - /* - * Loading another kernel to switch to if this one - * crashes. Free any current crash dump kernel before - * we corrupt it. - */ - - kimage_free(xchg(&kexec_crash_image, NULL)); - result = kimage_alloc_init(&image, entry, nr_segments, - segments, flags); - crash_map_reserved_pages(); - } else { - /* Loading another kernel to reboot into. */ - - result = kimage_alloc_init(&image, entry, nr_segments, - segments, flags); - } - if (result) - goto out; - - if (flags & KEXEC_PRESERVE_CONTEXT) - image->preserve_context = 1; - result = machine_kexec_prepare(image); - if (result) - goto out; - - for (i = 0; i < nr_segments; i++) { - result = kimage_load_segment(image, &image->segment[i]); - if (result) - goto out; - } - kimage_terminate(image); - if (flags & KEXEC_ON_CRASH) - crash_unmap_reserved_pages(); - } - /* Install the new kernel, and Uninstall the old */ - image = xchg(dest_image, image); + result = do_kexec_load(entry, nr_segments, segments, flags); -out: mutex_unlock(&kexec_mutex); - kimage_free(image); return result; } -- 2.1.0