From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752095AbaIXMvd (ORCPT ); Wed, 24 Sep 2014 08:51:33 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:55501 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750742AbaIXMvS (ORCPT ); Wed, 24 Sep 2014 08:51:18 -0400 X-AuditID: cbfec7f5-b7f776d000003e54-d2-5422be44aafc From: Andrey Ryabinin To: linux-kernel@vger.kernel.org Cc: Andrey Ryabinin , Dmitry Vyukov , Konstantin Serebryany , Dmitry Chernenkov , Andrey Konovalov , Yuri Gribov , Konstantin Khlebnikov , Sasha Levin , Christoph Lameter , Joonsoo Kim , Andrew Morton , Dave Hansen , Andi Kleen , Vegard Nossum , "H. Peter Anvin" , Dave Jones , x86@kernel.org, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar Subject: [PATCH v3 03/13] x86_64: load_percpu_segment: read irq_stack_union.gs_base before load_segment Date: Wed, 24 Sep 2014 16:43:59 +0400 Message-id: <1411562649-28231-4-git-send-email-a.ryabinin@samsung.com> X-Mailer: git-send-email 2.1.1 In-reply-to: <1411562649-28231-1-git-send-email-a.ryabinin@samsung.com> References: <1404905415-9046-1-git-send-email-a.ryabinin@samsung.com> <1411562649-28231-1-git-send-email-a.ryabinin@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrHLMWRmVeSWpSXmKPExsVy+t/xy7ou+5RCDHZ+tLLY9usRm8XvvTNZ LeasX8NmceTad3aL69/eMFp8evmA0WLL9SYmi+cPH7JbTHjYxm4xbaO4xcruZjaL7c/eMlms 7HzAanF51xw2i3tr/rNaXDqwgMli8ZHbzBbvnk1mtti8aSqzxdVVB9ktfmx4zOog6jF/50dG j52z7rJ7LNhU6rF4z0smj02rOtk8Nn2axO7R9fYKk8e7c+fYPU7M+M3i8eTKdCaPj09vsXi8 33eVzaNvyypGj8+b5DxOtHxhDeCP4rJJSc3JLEst0rdL4MrYc/8+U8FG7orzq3vYGhhvcXYx cnJICJhIXF7RwwRhi0lcuLeerYuRi0NIYCmjxPZJK5ghnD4miSs3jrCBVLEJ6En8m7UdzBYR UJDY3PuMFaSIWeAOq8Thx9sYQRLCApkSK78fZQWxWQRUJX43/AVr4BVwk5hwYCEbxDo5ib2T V7OA2JwC7hIHfrxgh9jWxCixbO9vpgmMvAsYGVYxiqaWJhcUJ6XnGukVJ+YWl+al6yXn525i hMTR1x2MS49ZHWIU4GBU4uGdKK4UIsSaWFZcmXuIUYKDWUmEN2wPUIg3JbGyKrUoP76oNCe1 +BAjEwenVAPjuUcsNa+UZI/2rzY2jvllcGZx4D2bn4Krfl78cWVKkmH4N/fsuh1//t816zyi MCf1GJMvU2uuxZ0Z8xm49DvyX1vOyMnSYXBcvdi/+N2cv7XvO1zDuiIW25bu0mBcdPjU12ol 7ht22bxX/NYvNp+0LepDZXEmd9rh20xTduex2vQov/32ayWPEktxRqKhFnNRcSIAT5o+QIEC AAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Reading irq_stack_union.gs_base after load_segment creates troubles for kasan. Compiler inserts __asan_load in between load_segment and wrmsrl. If kernel built with stackprotector this will result in boot failure because __asan_load has stackprotector. To avoid this irq_stack_union.gs_base stored to temporary variable before load_segment, so __asan_load will be called before load_segment(). There are two alternative ways to fix this: a) Add __attribute__((no_sanitize_address)) to load_percpu_segment(), which tells compiler to not instrument this function. However this will result in build failure with CONFIG_KASAN=y and CONFIG_OPTIMIZE_INLINING=y. b) Add -fno-stack-protector for mm/kasan/kasan.c Signed-off-by: Andrey Ryabinin --- arch/x86/kernel/cpu/common.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index fe52f2d..51d393f 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -389,8 +389,10 @@ void load_percpu_segment(int cpu) #ifdef CONFIG_X86_32 loadsegment(fs, __KERNEL_PERCPU); #else + void *gs_base = per_cpu(irq_stack_union.gs_base, cpu); + loadsegment(gs, 0); - wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu)); + wrmsrl(MSR_GS_BASE, (unsigned long)gs_base); #endif load_stack_canary_segment(); } -- 2.1.1