From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932658AbcHKQUy (ORCPT ); Thu, 11 Aug 2016 12:20:54 -0400 Received: from terminus.zytor.com ([198.137.202.10]:60108 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750708AbcHKQUv (ORCPT ); Thu, 11 Aug 2016 12:20:51 -0400 Date: Thu, 11 Aug 2016 09:19:45 -0700 From: tip-bot for Alex Thorlton Message-ID: Cc: jpoimboe@redhat.com, brgerst@gmail.com, travis@sgi.com, luto@kernel.org, tglx@linutronix.de, peterz@infradead.org, dvlasenk@redhat.com, bp@alien8.de, ard.biesheuvel@linaro.org, mingo@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, rja@sgi.com, bp@suse.de, torvalds@linux-foundation.org, athorlton@sgi.com, matt@codeblueprint.co.uk Reply-To: hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, athorlton@sgi.com, matt@codeblueprint.co.uk, bp@suse.de, rja@sgi.com, luto@kernel.org, jpoimboe@redhat.com, brgerst@gmail.com, travis@sgi.com, mingo@kernel.org, peterz@infradead.org, tglx@linutronix.de, bp@alien8.de, dvlasenk@redhat.com, ard.biesheuvel@linaro.org In-Reply-To: <1470912120-22831-2-git-send-email-matt@codeblueprint.co.uk> References: <1470912120-22831-2-git-send-email-matt@codeblueprint.co.uk> To: linux-tip-commits@vger.kernel.org Subject: [tip:efi/urgent] x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case Git-Commit-ID: f72075c9eda8a43aeea2f9dbb8d187afd4a76f0b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: f72075c9eda8a43aeea2f9dbb8d187afd4a76f0b Gitweb: http://git.kernel.org/tip/f72075c9eda8a43aeea2f9dbb8d187afd4a76f0b Author: Alex Thorlton AuthorDate: Thu, 11 Aug 2016 11:41:59 +0100 Committer: Ingo Molnar CommitDate: Thu, 11 Aug 2016 13:55:36 +0200 x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case This problem has actually been in the UV code for a while, but we didn't catch it until recently, because we had been relying on EFI_OLD_MEMMAP to allow our systems to boot for a period of time. We noticed the issue when trying to kexec a recent community kernel, where we hit this NULL pointer dereference in efi_sync_low_kernel_mappings(): [ 0.337515] BUG: unable to handle kernel NULL pointer dereference at 0000000000000880 [ 0.346276] IP: [] efi_sync_low_kernel_mappings+0x5d/0x1b0 The problem doesn't show up with EFI_OLD_MEMMAP because we skip the chunk of setup_efi_state() that sets the efi_loader_signature for the kexec'd kernel. When the kexec'd kernel boots, it won't set EFI_BOOT in setup_arch, so we completely avoid the bug. We always kexec with noefi on the command line, so this shouldn't be an issue, but since we're not actually checking for efi_runtime_disabled in uv_bios_init(), we end up trying to do EFI runtime callbacks when we shouldn't be. This patch just adds a check for efi_runtime_disabled in uv_bios_init() so that we don't map in uv_systab when runtime_disabled == true. Signed-off-by: Alex Thorlton Signed-off-by: Matt Fleming Cc: # v4.7 Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Mike Travis Cc: Peter Zijlstra Cc: Russ Anderson Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1470912120-22831-2-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar --- arch/x86/platform/uv/bios_uv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c index 66b2166..0df8a03 100644 --- a/arch/x86/platform/uv/bios_uv.c +++ b/arch/x86/platform/uv/bios_uv.c @@ -187,7 +187,8 @@ EXPORT_SYMBOL_GPL(uv_bios_set_legacy_vga_target); void uv_bios_init(void) { uv_systab = NULL; - if ((efi.uv_systab == EFI_INVALID_TABLE_ADDR) || !efi.uv_systab) { + if ((efi.uv_systab == EFI_INVALID_TABLE_ADDR) || + !efi.uv_systab || efi_runtime_disabled()) { pr_crit("UV: UVsystab: missing\n"); return; }