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=-7.8 required=3.0 tests=DATE_IN_PAST_06_12, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 AAA05C04A6B for ; Wed, 8 May 2019 17:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7649921530 for ; Wed, 8 May 2019 17:03:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729024AbfEHRDI (ORCPT ); Wed, 8 May 2019 13:03:08 -0400 Received: from mga17.intel.com ([192.55.52.151]:26497 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728966AbfEHRDE (ORCPT ); Wed, 8 May 2019 13:03:04 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 May 2019 10:03:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,446,1549958400"; d="scan'208";a="169697573" Received: from chang-linux-3.sc.intel.com ([172.25.66.171]) by fmsmga002.fm.intel.com with ESMTP; 08 May 2019 10:03:03 -0700 From: "Chang S. Bae" To: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Andi Kleen Cc: Ravi Shankar , "Chang S . Bae" , LKML Subject: [PATCH v7 08/18] x86/fsgsbase/64: When copying a thread, use the FSGSBASE instructions Date: Wed, 8 May 2019 03:02:23 -0700 Message-Id: <1557309753-24073-9-git-send-email-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1557309753-24073-1-git-send-email-chang.seok.bae@intel.com> References: <1557309753-24073-1-git-send-email-chang.seok.bae@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Copy real FS/GSBASE values instead of approximation when FSGSBASE is enabled. Suggested-by: Andy Lutomirski Signed-off-by: Chang S. Bae Cc: Thomas Gleixner Cc: Ingo Molnar Cc: H. Peter Anvin Cc: Andi Kleen --- arch/x86/kernel/process_64.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index e2089c9..8610df7 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -428,7 +428,8 @@ unsigned long x86_fsbase_read_task(struct task_struct *task) if (task == current) fsbase = x86_fsbase_read_cpu(); - else if (task->thread.fsindex == 0) + else if (static_cpu_has(X86_FEATURE_FSGSBASE) || + (task->thread.fsindex == 0)) fsbase = task->thread.fsbase; else fsbase = x86_fsgsbase_read_task(task, task->thread.fsindex); @@ -442,7 +443,8 @@ unsigned long x86_gsbase_read_task(struct task_struct *task) if (task == current) gsbase = x86_gsbase_read_cpu_inactive(); - else if (task->thread.gsindex == 0) + else if (static_cpu_has(X86_FEATURE_FSGSBASE) || + (task->thread.gsindex == 0)) gsbase = task->thread.gsbase; else gsbase = x86_fsgsbase_read_task(task, task->thread.gsindex); @@ -482,10 +484,11 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, p->thread.sp = (unsigned long) fork_frame; p->thread.io_bitmap_ptr = NULL; - savesegment(gs, p->thread.gsindex); - p->thread.gsbase = p->thread.gsindex ? 0 : me->thread.gsbase; - savesegment(fs, p->thread.fsindex); - p->thread.fsbase = p->thread.fsindex ? 0 : me->thread.fsbase; + save_fsgs(me); + p->thread.fsindex = me->thread.fsindex; + p->thread.fsbase = me->thread.fsbase; + p->thread.gsindex = me->thread.gsindex; + p->thread.gsbase = me->thread.gsbase; savesegment(es, p->thread.es); savesegment(ds, p->thread.ds); memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); -- 2.7.4