From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753205AbcEJXev (ORCPT ); Tue, 10 May 2016 19:34:51 -0400 Received: from mga11.intel.com ([192.55.52.93]:46083 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753107AbcEJXes (ORCPT ); Tue, 10 May 2016 19:34:48 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,606,1455004800"; d="scan'208";a="100873286" From: Yu-cheng Yu To: linux-kernel@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar Cc: Dave Hansen , Andy Lutomirski , Borislav Petkov , Sai Praneeth Prakhya , "Ravi V. Shankar" , Fenghua Yu , Yu-cheng Yu Subject: [PATCH v6 12/13] x86/xsaves: Fix fpstate_init() for XRSTORS Date: Tue, 10 May 2016 16:30:04 -0700 Message-Id: X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In XSAVES mode if fpstate_init() is used to initialize a task's extended state area, xsave.header.xcomp_bv[63] must be set. Otherwise, when the task is scheduled, a warning is triggered from copy_kernel_to_xregs(). One such test case is: setting an invalid extended state through PTRACE. When xstateregs_set() rejects the syscall and re-initializes the task's extended state area. This triggers the warning mentioned above. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/fpu/types.h | 6 ++++++ arch/x86/kernel/fpu/core.c | 4 ++++ 2 files changed, 10 insertions(+) diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index 12dd648..48df486 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -232,6 +232,12 @@ struct xstate_header { } __attribute__((packed)); /* + * xstate_header.xcomp_bv[63] indicates that the extended_state_area + * is in compacted format. + */ +#define XCOMP_BV_COMPACTED_FORMAT ((u64)1 << 63) + +/* * This is our most modern FPU state format, as saved by the XSAVE * and restored by the XRSTOR instructions. * diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index dfd29ac..9ed096f 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include @@ -224,6 +225,9 @@ void fpstate_init(union fpregs_state *state) memset(state, 0, fpu_kernel_xstate_size); + if (cpu_has_xsaves) + state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT; + if (cpu_has_fxsr) fpstate_init_fxstate(&state->fxsave); else -- 1.9.1