From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932276AbbCFIiw (ORCPT ); Fri, 6 Mar 2015 03:38:52 -0500 Received: from terminus.zytor.com ([198.137.202.10]:59235 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932412AbbCFIif (ORCPT ); Fri, 6 Mar 2015 03:38:35 -0500 Date: Fri, 6 Mar 2015 00:37:41 -0800 From: tip-bot for Andy Lutomirski Message-ID: Cc: mingo@kernel.org, torvalds@linux-foundation.org, rusty@rustcorp.com.au, konrad.wilk@oracle.com, linux-kernel@vger.kernel.org, dvlasenk@redhat.com, boris.ostrovsky@oracle.com, hpa@zytor.com, bp@alien8.de, tglx@linutronix.de, luto@amacapital.net, oleg@redhat.com Reply-To: oleg@redhat.com, luto@amacapital.net, bp@alien8.de, tglx@linutronix.de, hpa@zytor.com, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, dvlasenk@redhat.com, konrad.wilk@oracle.com, torvalds@linux-foundation.org, rusty@rustcorp.com.au, mingo@kernel.org In-Reply-To: <8d675581859712bee09a055ed8f785d80dac1eca.1425611534.git.luto@amacapital.net> References: <8d675581859712bee09a055ed8f785d80dac1eca.1425611534.git.luto@amacapital.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/asm/entry: Add this_cpu_sp0() to read sp0 for the current cpu Git-Commit-ID: 8ef46a672a7d852709561d10672b6eaa8a4acd82 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 Commit-ID: 8ef46a672a7d852709561d10672b6eaa8a4acd82 Gitweb: http://git.kernel.org/tip/8ef46a672a7d852709561d10672b6eaa8a4acd82 Author: Andy Lutomirski AuthorDate: Thu, 5 Mar 2015 19:19:02 -0800 Committer: Ingo Molnar CommitDate: Fri, 6 Mar 2015 08:32:57 +0100 x86/asm/entry: Add this_cpu_sp0() to read sp0 for the current cpu We currently store references to the top of the kernel stack in multiple places: kernel_stack (with an offset) and init_tss.x86_tss.sp0 (no offset). The latter is defined by hardware and is a clean canonical way to find the top of the stack. Add an accessor so we can start using it. This needs minor paravirt tweaks. On native, sp0 defines the top of the kernel stack and is therefore always correct. On Xen and lguest, the hypervisor tracks the top of the stack, but we want to start reading sp0 in the kernel. Fixing this is simple: just update our local copy of sp0 as well as the hypervisor's copy on task switches. Signed-off-by: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Konrad Rzeszutek Wilk Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Rusty Russell Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/8d675581859712bee09a055ed8f785d80dac1eca.1425611534.git.luto@amacapital.net Signed-off-by: Ingo Molnar --- arch/x86/include/asm/processor.h | 5 +++++ arch/x86/kernel/process.c | 1 + arch/x86/lguest/boot.c | 1 + arch/x86/xen/enlighten.c | 1 + 4 files changed, 8 insertions(+) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 7be2c9a..71c3a82 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -564,6 +564,11 @@ static inline void native_swapgs(void) #endif } +static inline unsigned long this_cpu_sp0(void) +{ + return this_cpu_read_stable(init_tss.x86_tss.sp0); +} + #ifdef CONFIG_PARAVIRT #include #else diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 046e2d6..ff5c908 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -38,6 +38,7 @@ * on exact cacheline boundaries, to eliminate cacheline ping-pong. */ __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, init_tss) = INIT_TSS; +EXPORT_PER_CPU_SYMBOL_GPL(init_tss); #ifdef CONFIG_X86_64 static DEFINE_PER_CPU(unsigned char, is_idle); diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index ac4453d..8561585 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -1076,6 +1076,7 @@ static void lguest_load_sp0(struct tss_struct *tss, { lazy_hcall3(LHCALL_SET_STACK, __KERNEL_DS | 0x1, thread->sp0, THREAD_SIZE / PAGE_SIZE); + tss->x86_tss.sp0 = thread->sp0; } /* Let's just say, I wouldn't do debugging under a Guest. */ diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 5240f56..81665c9 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -912,6 +912,7 @@ static void xen_load_sp0(struct tss_struct *tss, mcs = xen_mc_entry(0); MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->sp0); xen_mc_issue(PARAVIRT_LAZY_CPU); + tss->x86_tss.sp0 = thread->sp0; } static void xen_set_iopl_mask(unsigned mask)