From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S971755AbeCSUzu (ORCPT ); Mon, 19 Mar 2018 16:55:50 -0400 Received: from mga14.intel.com ([192.55.52.115]:62509 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968538AbeCSSIz (ORCPT ); Mon, 19 Mar 2018 14:08:55 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,331,1517904000"; d="scan'208";a="39330599" From: "Chang S. Bae" To: x86@kernel.org Cc: luto@kernel.org, ak@linux.intel.com, hpa@zytor.com, markus.t.metzger@intel.com, tony.luck@intel.com, ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org, chang.seok.bae@intel.com Subject: [PATCH 12/15] x86/fsgsbase/64: When copying a thread, use FSGSBASE if enabled Date: Mon, 19 Mar 2018 10:49:24 -0700 Message-Id: <1521481767-22113-13-git-send-email-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521481767-22113-1-git-send-email-chang.seok.bae@intel.com> References: <1521481767-22113-1-git-send-email-chang.seok.bae@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When FSGSBASE enabled, copy real FS/GS base values instead of approximation. Factor out to save_fsgs() does not yield the exact same behavior, because save_base_legacy() does not copy FS/GS base when index is zero. Signed-off-by: Chang S. Bae Cc: Andy Lutomirski Cc: H. Peter Anvin Cc: Andi Kleen --- arch/x86/kernel/process_64.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 7249a54..5aae132 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -491,10 +491,16 @@ 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; + savesegment(gs, p->thread.gsindex); + if (static_cpu_has(X86_FEATURE_FSGSBASE)) { + p->thread.fsbase = rdfsbase(); + p->thread.gsbase = rd_shadow_gsbase(); + } else { + /* save_base_legacy() does not set base when index is zero. */ + p->thread.fsbase = p->thread.fsindex ? 0 : me->thread.fsbase; + p->thread.gsbase = p->thread.gsindex ? 0 : 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