From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751835AbdAWXAX (ORCPT ); Mon, 23 Jan 2017 18:00:23 -0500 Received: from mga11.intel.com ([192.55.52.93]:59583 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751723AbdAWXAV (ORCPT ); Mon, 23 Jan 2017 18:00:21 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,275,1477983600"; d="scan'208";a="34466223" From: Yu-cheng Yu To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, Andy Lutomirski , Borislav Petkov , Dave Hansen , Fenghua Yu , Joakim Tjernlund , "Ravi V. Shankar" , haokexin@gmail.com Cc: Yu-cheng Yu Subject: [PATCH] x86/fpu/xstate: Fix xcomp_bv in XSAVES header Date: Mon, 23 Jan 2017 14:54:44 -0800 Message-Id: <1485212084-4418-1-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 The compacted-format XSAVES area is determined at boot time and never changed after. The field xsave.header.xcomp_bv indicates which components are in the fixed XSAVES format. In fpstate_init() we did not set xcomp_bv to reflect the XSAVES format since at the time there is no valid data. However, after we do copy_init_fpstate_to_fpregs() in fpu__clear(), as in commit: b22cbe404a9cc3c7949e380fa1861e31934c8978, and when __fpu_restore_sig() does fpu__restore() for a COMPAT-mode app, a #GP occurs. This can be easily triggered by doing valgrind on a COMPAT-mode "Hello World," as reported by Joakim Tjernlund and others: https://bugzilla.kernel.org/show_bug.cgi?id=190061 Fix it by setting xcomp_bv correctly. Signed-off-by: Yu-cheng Yu Reported-by: Joakim Tjernlund --- arch/x86/kernel/fpu/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index c289e2f..e540dc1 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include @@ -235,7 +236,8 @@ void fpstate_init(union fpregs_state *state) * it will #GP. Make sure it is replaced after the memset(). */ if (static_cpu_has(X86_FEATURE_XSAVES)) - state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT; + state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | + xfeatures_mask; if (static_cpu_has(X86_FEATURE_FXSR)) fpstate_init_fxstate(&state->fxsave); -- 1.9.1