From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FB1FC433F5 for ; Fri, 1 Oct 2021 22:46:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A54661ADF for ; Fri, 1 Oct 2021 22:46:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356298AbhJAWsD (ORCPT ); Fri, 1 Oct 2021 18:48:03 -0400 Received: from mga17.intel.com ([192.55.52.151]:38078 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356232AbhJAWre (ORCPT ); Fri, 1 Oct 2021 18:47:34 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10124"; a="205756685" X-IronPort-AV: E=Sophos;i="5.85,340,1624345200"; d="scan'208";a="205756685" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Oct 2021 15:44:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.85,340,1624345200"; d="scan'208";a="565344031" Received: from chang-linux-3.sc.intel.com ([172.25.66.175]) by fmsmga002.fm.intel.com with ESMTP; 01 Oct 2021 15:44:20 -0700 From: "Chang S. Bae" To: bp@suse.de, luto@kernel.org, tglx@linutronix.de, mingo@kernel.org, x86@kernel.org Cc: len.brown@intel.com, lenb@kernel.org, dave.hansen@intel.com, thiago.macieira@intel.com, jing2.liu@intel.com, ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org, chang.seok.bae@intel.com Subject: [PATCH v11 28/29] x86/arch_prctl: ARCH_GET_FEATURES_WITH_KERNEL_ASSISTANCE Date: Fri, 1 Oct 2021 15:37:27 -0700 Message-Id: <20211001223728.9309-29-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211001223728.9309-1-chang.seok.bae@intel.com> References: <20211001223728.9309-1-chang.seok.bae@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org arch_prctl(ARCH_GET_FEATURES_WITH_KERNEL_ASSISTANCE, u64 *bitmask) Return the bitmask of the kernel-supported features. If XSAVE is disabled, the bitmask indicates only legacy states. Suggested-by: Borislav Petkov Signed-off-by: Chang S. Bae Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- Changes from v9: * Add as a new patch. (Thiago Macieira and Borislav Petkov) --- arch/x86/include/uapi/asm/prctl.h | 23 +++++++++++---------- arch/x86/kernel/fpu/xstate.c | 34 ++++++++++++++++++++----------- arch/x86/kernel/process.c | 1 + 3 files changed, 35 insertions(+), 23 deletions(-) diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h index c73e141ce90a..6912d5fe85f3 100644 --- a/arch/x86/include/uapi/asm/prctl.h +++ b/arch/x86/include/uapi/asm/prctl.h @@ -2,19 +2,20 @@ #ifndef _ASM_X86_PRCTL_H #define _ASM_X86_PRCTL_H -#define ARCH_SET_GS 0x1001 -#define ARCH_SET_FS 0x1002 -#define ARCH_GET_FS 0x1003 -#define ARCH_GET_GS 0x1004 +#define ARCH_SET_GS 0x1001 +#define ARCH_SET_FS 0x1002 +#define ARCH_GET_FS 0x1003 +#define ARCH_GET_GS 0x1004 -#define ARCH_GET_CPUID 0x1011 -#define ARCH_SET_CPUID 0x1012 +#define ARCH_GET_CPUID 0x1011 +#define ARCH_SET_CPUID 0x1012 -#define ARCH_SET_STATE_ENABLE 0x1021 -#define ARCH_GET_STATE_ENABLE 0x1022 +#define ARCH_GET_FEATURES_WITH_KERNEL_ASSISTANCE 0x1020 +#define ARCH_SET_STATE_ENABLE 0x1021 +#define ARCH_GET_STATE_ENABLE 0x1022 -#define ARCH_MAP_VDSO_X32 0x2001 -#define ARCH_MAP_VDSO_32 0x2002 -#define ARCH_MAP_VDSO_64 0x2003 +#define ARCH_MAP_VDSO_X32 0x2001 +#define ARCH_MAP_VDSO_32 0x2002 +#define ARCH_MAP_VDSO_64 0x2003 #endif /* _ASM_X86_PRCTL_H */ diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 81566a18643b..75db4def5ec5 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1299,6 +1299,24 @@ int realloc_xstate_buffer(struct fpu *fpu, u64 mask) return 0; } +/** + * get_features_mask_uabi - Get a feature list that the kernel supports + * Return: A bitmap that indicates which state the kernel enabled. + */ +static u64 get_features_mask_uabi(void) +{ + if (!cpu_feature_enabled(X86_FEATURE_FPU)) + return 0; + + if (use_xsave()) + return xfeatures_mask_uabi(); + + if (use_fxsr()) + return XFEATURE_MASK_FPSSE; + + return XFEATURE_MASK_FP; +} + /** * reset_state_perm - Reset a task's permission for dynamic user state * @@ -1329,7 +1347,7 @@ void reset_state_perm(struct task_struct *tsk) } /** - * do_arch_prctl_state - Read or write the state permission. + * do_arch_prctl_state - Handle xstate-related buffer or usage control * @fpu: A struct task_struct * pointer * @option: A subfunction of arch_prctl() * @arg2: Either a pointer to userspace memory or state-component @@ -1338,22 +1356,14 @@ void reset_state_perm(struct task_struct *tsk) */ long do_arch_prctl_state(struct task_struct *tsk, int option, unsigned long arg2) { - u64 features_mask; - - if (!cpu_feature_enabled(X86_FEATURE_FPU)) - features_mask = 0; - else if (use_fxsr()) - features_mask = XFEATURE_MASK_FPSSE; - else - features_mask = XFEATURE_MASK_FP; + u64 features_mask = get_features_mask_uabi(); switch (option) { + case ARCH_GET_FEATURES_WITH_KERNEL_ASSISTANCE: + return put_user(features_mask, (unsigned long __user *)arg2); case ARCH_SET_STATE_ENABLE: { u64 state_perm = arg2; - if (use_xsave()) - features_mask = xfeatures_mask_uabi(); - if (state_perm & ~features_mask) return -EINVAL; diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index b43e2b0f52f2..ae53ffd76882 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -1023,6 +1023,7 @@ long do_arch_prctl_common(struct task_struct *task, int option, return get_cpuid_mode(); case ARCH_SET_CPUID: return set_cpuid_mode(task, arg2); + case ARCH_GET_FEATURES_WITH_KERNEL_ASSISTANCE: case ARCH_SET_STATE_ENABLE: case ARCH_GET_STATE_ENABLE: return do_arch_prctl_state(task, option, arg2); -- 2.17.1