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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 7FCC4C47404 for ; Fri, 4 Oct 2019 18:17:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60CE7215EA for ; Fri, 4 Oct 2019 18:17:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389136AbfJDSRk (ORCPT ); Fri, 4 Oct 2019 14:17:40 -0400 Received: from mga07.intel.com ([134.134.136.100]:15531 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388586AbfJDSRG (ORCPT ); Fri, 4 Oct 2019 14:17:06 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Oct 2019 11:17:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,257,1566889200"; d="scan'208";a="204394808" Received: from chang-linux-3.sc.intel.com ([172.25.66.185]) by orsmga002.jf.intel.com with ESMTP; 04 Oct 2019 11:17:04 -0700 From: "Chang S. Bae" To: linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, luto@kernel.org Cc: hpa@zytor.com, dave.hansen@intel.com, tony.luck@intel.com, ak@linux.intel.com, ravi.v.shankar@intel.com, chang.seok.bae@intel.com Subject: [PATCH v9 12/17] x86/fsgsbase/64: Use FSGSBASE instructions on thread copy and ptrace Date: Fri, 4 Oct 2019 11:16:04 -0700 Message-Id: <1570212969-21888-13-git-send-email-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1570212969-21888-1-git-send-email-chang.seok.bae@intel.com> References: <1570212969-21888-1-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 When FSGSBASE is enabled, copying threads and reading FS/GS base using ptrace must read the actual values. When copying a thread, use fsgs_save() and copy the saved values. For ptrace, the bases must be read from memory regardless of the selector if FSGSBASE is enabled. Suggested-by: Andy Lutomirski Signed-off-by: Chang S. Bae Reviewed-by: Tony Luck Cc: Thomas Gleixner Cc: Borislav Petkov Cc: Andy Lutomirski Cc: H. Peter Anvin Cc: Dave Hansen Cc: Tony Luck Cc: Andi Kleen --- Changes from v8: none Changes from v7: * No code change * Massaged changelog by Andy Lutomirski --- 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 56c0e5b..b67f656 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -415,7 +415,8 @@ 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); @@ -429,7 +430,8 @@ 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); @@ -469,10 +471,11 @@ 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