Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932427AbbBZNNT (ORCPT ); Thu, 26 Feb 2015 08:13:19 -0500 Received: from terminus.zytor.com ([198.137.202.10]:53182 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932194AbbBZNNQ (ORCPT ); Thu, 26 Feb 2015 08:13:16 -0500 Date: Thu, 26 Feb 2015 05:12:31 -0800 From: tip-bot for Wang Nan Message-ID: Cc: tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, masami.hiramatsu.pt@hitachi.com, linux-kernel@vger.kernel.org, oleg@redhat.com, rostedt@goodmis.org, lizefan@huawei.com, wangnan0@huawei.com, luto@amacapital.net Reply-To: tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, masami.hiramatsu.pt@hitachi.com, linux-kernel@vger.kernel.org, oleg@redhat.com, lizefan@huawei.com, rostedt@goodmis.org, wangnan0@huawei.com, luto@amacapital.net In-Reply-To: <1424929779-13174-1-git-send-email-wangnan0@huawei.com> References: <1424929779-13174-1-git-send-email-wangnan0@huawei.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/traps: Enable DEBUG_STACK after cpu_init() for TRAP_DB/BP Git-Commit-ID: b4d8327024637cb2a1f7910dcb5d0ad7a096f473 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 Content-Length: 3196 Lines: 84 Commit-ID: b4d8327024637cb2a1f7910dcb5d0ad7a096f473 Gitweb: http://git.kernel.org/tip/b4d8327024637cb2a1f7910dcb5d0ad7a096f473 Author: Wang Nan AuthorDate: Thu, 26 Feb 2015 13:49:39 +0800 Committer: Ingo Molnar CommitDate: Thu, 26 Feb 2015 12:29:20 +0100 x86/traps: Enable DEBUG_STACK after cpu_init() for TRAP_DB/BP Before this patch early_trap_init() installs DEBUG_STACK for X86_TRAP_BP and X86_TRAP_DB. However, DEBUG_STACK doesn't work correctly until cpu_init() <-- trap_init(). This patch passes 0 to set_intr_gate_ist() and set_system_intr_gate_ist() instead of DEBUG_STACK to let it use same stack as kernel, and installs DEBUG_STACK for them in trap_init(). As core runs at ring 0 between early_trap_init() and trap_init(), there is no chance to get a bad stack before trap_init(). As NMI is also enabled in trap_init(), we don't need to care about is_debug_stack() and related things used in arch/x86/kernel/nmi.c. Signed-off-by: Wang Nan Reviewed-by: Masami Hiramatsu Acked-by: Steven Rostedt Cc: Cc: Cc: Cc: Link: http://lkml.kernel.org/r/1424929779-13174-1-git-send-email-wangnan0@huawei.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/traps.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 9d2073e..4281988 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -925,9 +925,17 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code) /* Set of traps needed for early debugging. */ void __init early_trap_init(void) { - set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK); + /* + * Don't set ist to DEBUG_STACK as it doesn't work until TSS is + * ready in cpu_init() <-- trap_init(). Before trap_init(), CPU + * runs at ring 0 so it is impossible to hit an invalid stack. + * Using the original stack works well enough at this early + * stage. DEBUG_STACK will be equipped after cpu_init() in + * trap_init(). + */ + set_intr_gate_ist(X86_TRAP_DB, &debug, 0); /* int3 can be called from all */ - set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK); + set_system_intr_gate_ist(X86_TRAP_BP, &int3, 0); #ifdef CONFIG_X86_32 set_intr_gate(X86_TRAP_PF, page_fault); #endif @@ -1005,6 +1013,15 @@ void __init trap_init(void) */ cpu_init(); + /* + * X86_TRAP_DB and X86_TRAP_BP have been set + * in early_trap_init(). However, DEBUG_STACK works only after + * cpu_init() loads TSS. See comments in early_trap_init(). + */ + set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK); + /* int3 can be called from all */ + set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK); + x86_init.irqs.trap_init(); #ifdef CONFIG_X86_64 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/