From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6062FECDFB8 for ; Thu, 19 Jul 2018 23:21:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1FE2320673 for ; Thu, 19 Jul 2018 23:21:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1FE2320673 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731103AbeGTAGT (ORCPT ); Thu, 19 Jul 2018 20:06:19 -0400 Received: from terminus.zytor.com ([198.137.202.136]:35185 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730255AbeGTAGT (ORCPT ); Thu, 19 Jul 2018 20:06:19 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w6JNJt9b2450918 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 19 Jul 2018 16:19:55 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w6JNJtf62450915; Thu, 19 Jul 2018 16:19:55 -0700 Date: Thu, 19 Jul 2018 16:19:55 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Joerg Roedel Message-ID: Cc: peterz@infradead.org, jroedel@suse.de, luto@kernel.org, aarcange@redhat.com, llong@redhat.com, pavel@ucw.cz, dave.hansen@intel.com, mingo@kernel.org, will.deacon@arm.com, eduval@amazon.com, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, David.Laight@aculab.com, tglx@linutronix.de, dhgutteridge@sympatico.ca, brgerst@gmail.com, torvalds@linux-foundation.org, jpoimboe@redhat.com, jgross@suse.com, jkosina@suse.cz, hpa@zytor.com, gregkh@linuxfoundation.org, boris.ostrovsky@oracle.com, bp@alien8.de Reply-To: llong@redhat.com, aarcange@redhat.com, pavel@ucw.cz, mingo@kernel.org, dave.hansen@intel.com, dvlasenk@redhat.com, will.deacon@arm.com, eduval@amazon.com, peterz@infradead.org, jroedel@suse.de, luto@kernel.org, jgross@suse.com, jkosina@suse.cz, torvalds@linux-foundation.org, jpoimboe@redhat.com, bp@alien8.de, gregkh@linuxfoundation.org, hpa@zytor.com, boris.ostrovsky@oracle.com, tglx@linutronix.de, dhgutteridge@sympatico.ca, David.Laight@aculab.com, linux-kernel@vger.kernel.org, brgerst@gmail.com In-Reply-To: <1531906876-13451-4-git-send-email-joro@8bytes.org> References: <1531906876-13451-4-git-send-email-joro@8bytes.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/pti] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler Git-Commit-ID: a6b744f3ce9d017dd86b28355de2d8e0d36496d4 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: a6b744f3ce9d017dd86b28355de2d8e0d36496d4 Gitweb: https://git.kernel.org/tip/a6b744f3ce9d017dd86b28355de2d8e0d36496d4 Author: Joerg Roedel AuthorDate: Wed, 18 Jul 2018 11:40:40 +0200 Committer: Thomas Gleixner CommitDate: Fri, 20 Jul 2018 01:11:36 +0200 x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler x86_tss.sp0 will be used to point to the entry stack later to use it as a trampoline stack for other kernel entry points besides SYSENTER. So store the real task stack pointer in x86_tss.sp1, which is otherwise unused by the hardware, as Linux doesn't make use of Ring 1. Signed-off-by: Joerg Roedel Signed-off-by: Thomas Gleixner Tested-by: Pavel Machek Cc: "H . Peter Anvin" Cc: linux-mm@kvack.org Cc: Linus Torvalds Cc: Andy Lutomirski Cc: Dave Hansen Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Peter Zijlstra Cc: Borislav Petkov Cc: Jiri Kosina Cc: Boris Ostrovsky Cc: Brian Gerst Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: Will Deacon Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli Cc: Waiman Long Cc: "David H . Gutteridge" Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-4-git-send-email-joro@8bytes.org --- arch/x86/kernel/asm-offsets_32.c | 9 +++++++-- arch/x86/kernel/process_32.c | 2 ++ 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c index 15b3f45b69cd..82826f2275cc 100644 --- a/arch/x86/kernel/asm-offsets_32.c +++ b/arch/x86/kernel/asm-offsets_32.c @@ -46,9 +46,14 @@ void foo(void) OFFSET(saved_context_gdt_desc, saved_context, gdt_desc); BLANK(); - /* Offset from the entry stack to task stack stored in TSS */ + /* + * Offset from the entry stack to task stack stored in TSS. Kernel entry + * happens on the per-cpu entry-stack, and the asm code switches to the + * task-stack pointer stored in x86_tss.sp1, which is a copy of + * task->thread.sp0 where entry code can find it. + */ DEFINE(TSS_entry2task_stack, - offsetof(struct cpu_entry_area, tss.x86_tss.sp0) - + offsetof(struct cpu_entry_area, tss.x86_tss.sp1) - offsetofend(struct cpu_entry_area, entry_stack_page.stack)); #ifdef CONFIG_STACKPROTECTOR diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 0ae659de21eb..ec62cc77388d 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -290,6 +290,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) this_cpu_write(cpu_current_top_of_stack, (unsigned long)task_stack_page(next_p) + THREAD_SIZE); + /* SYSENTER reads the task-stack from tss.sp1 */ + this_cpu_write(cpu_tss_rw.x86_tss.sp1, next_p->thread.sp0); /* * Restore %gs if needed (which is common)