From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753607AbcKPQ6x (ORCPT ); Wed, 16 Nov 2016 11:58:53 -0500 Received: from mga06.intel.com ([134.134.136.31]:60747 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751584AbcKPQ6w (ORCPT ); Wed, 16 Nov 2016 11:58:52 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,500,1473145200"; d="scan'208";a="31613356" From: Yu-cheng Yu To: linux-kernel@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar Cc: Yu-cheng Yu , Andy Lutomirski , Borislav Petkov , David Hansen , Fenghua Yu , "Ravi V. Shankar" Subject: [PATCH] x86/fpu: Fix invalid FPU ptrace state after execve Date: Wed, 16 Nov 2016 08:56:36 -0800 Message-Id: <1479315396-2131-1-git-send-email-yu-cheng.yu@intel.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Robert O'Callahan reported that after an execve PTRACE_GETREGSET NT_X86_XSTATE continues to return the pre-exec register values until the exec'ed task modifies FPU state. The test code is at https://bugzilla.redhat.com/attachment.cgi?id=1164286. What is happening is when eagerfpu is enabled, fpu__clear() did not properly clear fpstate. Fix it by doing just that. Signed-off-by: Yu-cheng Yu Reported-by: Robert O'Callahan Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Andy Lutomirski Cc: Borislav Petkov Cc: David Hansen Cc: Fenghua Yu Cc: "Ravi V. Shankar" --- arch/x86/kernel/fpu/core.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 4700401..4c203c4 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -521,14 +521,14 @@ void fpu__clear(struct fpu *fpu) { WARN_ON_FPU(fpu != ¤t->thread.fpu); /* Almost certainly an anomaly */ - if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) { - /* FPU state will be reallocated lazily at the first use. */ - fpu__drop(fpu); - } else { - if (!fpu->fpstate_active) { - fpu__activate_curr(fpu); - user_fpu_begin(); - } + fpu__drop(fpu); + + /* + * When eagerfpu is used, make sure fpstate is cleared and initialized. + */ + if (use_eager_fpu()) { + fpu__activate_curr(fpu); + user_fpu_begin(); copy_init_fpstate_to_fpregs(); } } -- 1.9.1