Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752904Ab2JRADU (ORCPT ); Wed, 17 Oct 2012 20:03:20 -0400 Received: from terminus.zytor.com ([198.137.202.10]:39464 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752729Ab2JRADS (ORCPT ); Wed, 17 Oct 2012 20:03:18 -0400 Message-ID: <507F473D.1060700@zytor.com> Date: Wed, 17 Oct 2012 17:03:09 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121009 Thunderbird/16.0 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk CC: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, lenb@kernel.org, linux-acpi@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 1/4] x86/wakeup/sleep: Check whether the TSS GDT descriptor is empty before using it. References: <1350481786-4969-1-git-send-email-konrad.wilk@oracle.com> <1350481786-4969-2-git-send-email-konrad.wilk@oracle.com> In-Reply-To: <1350481786-4969-2-git-send-email-konrad.wilk@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1689 Lines: 50 On 10/17/2012 06:49 AM, Konrad Rzeszutek Wilk wrote: > We check the TSS descriptor before we try to dereference it. > Also fix up the value to use the #defines. > > Signed-off-by: Konrad Rzeszutek Wilk > --- > arch/x86/power/cpu.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c > index 218cdb1..c17370e 100644 > --- a/arch/x86/power/cpu.c > +++ b/arch/x86/power/cpu.c > @@ -133,7 +133,9 @@ static void fix_processor_context(void) > { > int cpu = smp_processor_id(); > struct tss_struct *t = &per_cpu(init_tss, cpu); > - > +#ifdef CONFIG_X86_64 > + struct desc_struct *desc = get_cpu_gdt_table(cpu); > +#endif > set_tss_desc(cpu, t); /* > * This just modifies memory; should not be > * necessary. But... This is necessary, because > @@ -142,7 +144,8 @@ static void fix_processor_context(void) > */ > > #ifdef CONFIG_X86_64 > - get_cpu_gdt_table(cpu)[GDT_ENTRY_TSS].type = 9; > + if (!desc_empty(&desc[GDT_ENTRY_TSS])) > + desc[GDT_ENTRY_TSS].type = DESC_TSS; > > syscall_init(); /* This sets MSR_*STAR and related */ > #endif > Why is this patch necessary? Presumably there is something further down the line which depends on the TSS descriptor being empty, but if so, what? -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- 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/