From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from terminus.zytor.com ([198.137.202.10]:59222 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752452AbcKUKgh (ORCPT ); Mon, 21 Nov 2016 05:36:37 -0500 Date: Mon, 21 Nov 2016 02:34:54 -0800 From: tip-bot for Yu-cheng Yu Message-ID: Cc: yu-cheng.yu@intel.com, stable@vger.kernel.org, peterz@infradead.org, mingo@kernel.org, ravi.v.shankar@intel.com, luto@kernel.org, bp@suse.de, linux-kernel@vger.kernel.org, fenghua.yu@intel.com, robert@ocallahan.org, dave.hansen@linux.intel.com, hpa@zytor.com, tglx@linutronix.de, torvalds@linux-foundation.org Reply-To: mingo@kernel.org, ravi.v.shankar@intel.com, yu-cheng.yu@intel.com, stable@vger.kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, fenghua.yu@intel.com, hpa@zytor.com, dave.hansen@linux.intel.com, robert@ocallahan.org, tglx@linutronix.de, torvalds@linux-foundation.org, luto@kernel.org, bp@suse.de In-Reply-To: <1479402695-6553-1-git-send-email-yu-cheng.yu@intel.com> References: <1479402695-6553-1-git-send-email-yu-cheng.yu@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/fpu: Fix invalid FPU ptrace state after execve() MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: stable-owner@vger.kernel.org List-ID: Commit-ID: b22cbe404a9cc3c7949e380fa1861e31934c8978 Gitweb: http://git.kernel.org/tip/b22cbe404a9cc3c7949e380fa1861e31934c8978 Author: Yu-cheng Yu AuthorDate: Thu, 17 Nov 2016 09:11:35 -0800 Committer: Ingo Molnar CommitDate: Mon, 21 Nov 2016 10:38:35 +0100 x86/fpu: Fix invalid FPU ptrace state after execve() 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 fpu__clear() does not properly clear fpstate. Fix it by doing just that. Reported-by: Robert O'Callahan Signed-off-by: Yu-cheng Yu Cc: Cc: Andy Lutomirski Cc: Borislav Petkov Cc: David Hansen Cc: Fenghua Yu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Ravi V. Shankar Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1479402695-6553-1-git-send-email-yu-cheng.yu@intel.com Signed-off-by: Ingo Molnar --- 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..ebb4e95 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); + + /* + * Make sure fpstate is cleared and initialized. + */ + if (static_cpu_has(X86_FEATURE_FPU)) { + fpu__activate_curr(fpu); + user_fpu_begin(); copy_init_fpstate_to_fpregs(); } }