Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751602AbdIAI0h (ORCPT ); Fri, 1 Sep 2017 04:26:37 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:38756 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751483AbdIAI0e (ORCPT ); Fri, 1 Sep 2017 04:26:34 -0400 X-Google-Smtp-Source: ADKCNb4NRNEMYqXVB97SlXwJ9mckbnqvle8BnkEvQ7cfIOrlva60/mJH9esjsein3GqN2y8YYE4vYw== Date: Fri, 1 Sep 2017 10:26:30 +0200 From: Ingo Molnar To: Andrei Vagin Cc: tip-bot for Jacob Shin , Thomas Gleixner , Cyrill Gorcunov , linux-tip-commits@vger.kernel.org, luto@kernel.org, peterz@infradead.org, rostedt@goodmis.org, linux-kernel@vger.kernel.org, hpa@zytor.com, brgerst@gmail.com, jpoimboe@redhat.com, bp@alien8.de, torvalds@linux-foundation.org, dvlasenk@redhat.com Subject: [PATCH] x86/idt: Fix the X86_TRAP_BP gate Message-ID: <20170901082630.xvyi5bwk6etmppqc@gmail.com> References: <20170901062815.GA349@outlook.office365.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170901062815.GA349@outlook.office365.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2047 Lines: 64 Hi Andrei, * Andrei Vagin wrote: > Hi Thomas, > > We run CRIU tests for linux-next and today they detected an issue. I've > bisected this problem and it looks like a problem is in this patch. Ok, there appears to be a bug in that conversion - does the patch below fix the regression for you? Thanks, Ingo ================================> Subject: x86/idt: Fix the X86_TRAP_BP gate From: Ingo Molnar Andrei Vagin reported a CRIU regression and bisected it back to: 90f6225fba0c ("x86/idt: Move IST stack based traps to table init") This table init conversion loses the system-gate property of X86_TRAP_BP and erroneously moves it from DPL3 to DPL0. Fix it. Reported-by: Andrei Vagin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- arch/x86/kernel/idt.c | 6 +++++- arch/x86/kernel/idt.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) Index: tip/arch/x86/kernel/idt.c =================================================================== --- tip.orig/arch/x86/kernel/idt.c +++ tip/arch/x86/kernel/idt.c @@ -44,6 +44,10 @@ struct idt_data { #define ISTG(_vector, _addr, _ist) \ G(_vector, _addr, _ist, GATE_INTERRUPT, DPL0, __KERNEL_CS) +/* System interrupt gate with interrupt stack */ +#define SISTG(_vector, _addr, _ist) \ + G(_vector, _addr, _ist, GATE_INTERRUPT, DPL3, __KERNEL_CS) + /* Task gate */ #define TSKG(_vector, _gdt) \ G(_vector, NULL, DEFAULT_STACK, GATE_TASK, DPL0, _gdt << 3) @@ -181,7 +185,7 @@ gate_desc debug_idt_table[IDT_ENTRIES] _ static const __initdata struct idt_data ist_idts[] = { ISTG(X86_TRAP_DB, debug, DEBUG_STACK), ISTG(X86_TRAP_NMI, nmi, NMI_STACK), - ISTG(X86_TRAP_BP, int3, DEBUG_STACK), + SISTG(X86_TRAP_BP, int3, DEBUG_STACK), ISTG(X86_TRAP_DF, double_fault, DOUBLEFAULT_STACK), #ifdef CONFIG_X86_MCE ISTG(X86_TRAP_MC, &machine_check, MCE_STACK),