Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754575AbdIGHm6 (ORCPT ); Thu, 7 Sep 2017 03:42:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44090 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754541AbdIGHmz (ORCPT ); Thu, 7 Sep 2017 03:42:55 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com A5F05800A4 Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=bhe@redhat.com From: Baoquan He To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, thgarnie@google.com, keescook@chromium.org, akpm@linux-foundation.org, yamada.masahiro@socionext.com, rja@hpe.com, frank.ramsay@hpe.com, Baoquan He Subject: [PATCH v2 RESEND 2/2] x86/mm/KASLR: Do not adapt the size of the direct mapping section for SGI UV system Date: Thu, 7 Sep 2017 15:42:30 +0800 Message-Id: <1504770150-25456-3-git-send-email-bhe@redhat.com> In-Reply-To: <1504770150-25456-1-git-send-email-bhe@redhat.com> References: <1504770150-25456-1-git-send-email-bhe@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 07 Sep 2017 07:42:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3084 Lines: 86 On SGI UV system, kernel often hangs when KASLR is enabled. Disabling KASLR makes kernel work well. The back trace is: kernel BUG at arch/x86/mm/init_64.c:311! invalid opcode: 0000 [#1] SMP [...] RIP: 0010:__init_extra_mapping+0x188/0x196 [...] Call Trace: init_extra_mapping_uc+0x13/0x15 map_high+0x67/0x75 map_mmioh_high_uv3+0x20a/0x219 uv_system_init_hub+0x12d9/0x1496 uv_system_init+0x27/0x29 native_smp_prepare_cpus+0x28d/0x2d8 kernel_init_freeable+0xdd/0x253 ? rest_init+0x80/0x80 kernel_init+0xe/0x110 ret_from_fork+0x2c/0x40 This is because the SGI UV system need map its MMIOH region to the direct mapping section, and the mapping happens in rest_init() which is much later than the calling of kernel_randomize_memory() to do mm KASLR. So mm KASLR can't count in the size of the MMIOH region when caculate the needed size of address space for the direct mapping section. When KASLR is disabled, there are 64TB address space for both system RAM and the MMIOH regions to share. When KASLR is enabled, the current code of mm KASLR only reserves the actual size of system RAM plus extra 10TB for the direct mapping. Thus later the MMIOH mapping could go beyond the upper bound of the direct mapping to step into VMALLOC or VMEMMAP area. Then BUG_ON() in __init_extra_mapping() will be triggered. E.g on the SGI UV3 machine where this bug is reported , there are two MMIOH regions: [ 1.519001] UV: Map MMIOH0_HI 0xffc00000000 - 0x100000000000 [ 1.523001] UV: Map MMIOH1_HI 0x100000000000 - 0x200000000000 They are [16TB-16G, 16TB) and [16TB, 32TB). On this machine, 512G RAM are spread out to 1TB regions. Then above two SGI MMIOH regions also will be mapped into the direct mapping section. To fix it, we need check if it's SGI UV system by calling is_early_uv_system() in kernel_randomize_memory(). If yes, do not adapt the size of the direct mapping section, just keep it as 64TB. Signed-off-by: Baoquan He Reviewed-by: Thomas Garnier Acked-by: Mike Travis Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: Thomas Garnier Cc: Kees Cook Cc: Andrew Morton Cc: Masahiro Yamada --- arch/x86/mm/kaslr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c index af599167fe3c..4d68c08df82d 100644 --- a/arch/x86/mm/kaslr.c +++ b/arch/x86/mm/kaslr.c @@ -27,6 +27,7 @@ #include #include #include +#include #include "mm_internal.h" @@ -123,7 +124,7 @@ void __init kernel_randomize_memory(void) CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING; /* Adapt phyiscal memory region size based on available memory */ - if (memory_tb < kaslr_regions[0].size_tb) + if (memory_tb < kaslr_regions[0].size_tb && !is_early_uv_system()) kaslr_regions[0].size_tb = memory_tb; /* Calculate entropy available between regions */ -- 2.5.5