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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 281CFC48BC2 for ; Wed, 23 Jun 2021 12:26:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 128966108E for ; Wed, 23 Jun 2021 12:26:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231904AbhFWM20 (ORCPT ); Wed, 23 Jun 2021 08:28:26 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:36808 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231375AbhFWM1M (ORCPT ); Wed, 23 Jun 2021 08:27:12 -0400 Message-Id: <20210623121457.804115017@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624451094; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=lxQiNshRMEz1wUQuKKb+ne9kj37Zxi6y6WEVTTrflSE=; b=OtJi4e5zQFgCDuIw3/sv6WdmxLaOyJ54pfdTuGshn7gJgsX+V+Ay7zyOwM60bVxhWaiTPr 1LKiH/KU9l7NNyi/F3sF+8XNP9GE1lvCmcBmJOGvFpOdHgsI50TOpRmIRVsjA/CLhIGM1d RsnDupQ0oT7i9KSGpgVOI3fnbuA3gApgRKGtEB7X0koDICw2lIe3xMyn3c/vN53sKMdtfG kCdbK61GXGTmfFd3SAZcPHQyAApOLLQGnnNc2Ro+lq4+srjC/joct9Sazgn9YFTEcbOdw+ CNlo0kkd0LWMSLKqtq8AzyojoneYIFY5iye3tbnBE1AJk190VgIhqw3SWLhC5Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624451094; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=lxQiNshRMEz1wUQuKKb+ne9kj37Zxi6y6WEVTTrflSE=; b=0gcoAcekwywrMZYG7L/SgfzsqP3Y3TjazT+YSwl7zNlA9hgCXpFcL0OvJhU5PGej2M0Gsc CN+O5MpKcnprWJBA== Date: Wed, 23 Jun 2021 14:02:32 +0200 From: Thomas Gleixner To: LKML Cc: Andy Lutomirski , Dave Hansen , Fenghua Yu , Tony Luck , Yu-cheng Yu , Sebastian Andrzej Siewior , Borislav Petkov , Peter Zijlstra , Kan Liang , "Chang Seok Bae" , Megha Dey , Oliver Sang Subject: [patch V4 65/65] x86/fpu/signal: Let xrstor handle the features to init References: <20210623120127.327154589@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is no reason to do an extra XRSTOR from initfp_state for feature bits which have been cleared by user space in the FX magic xfeatures storage. Just clear them in the task's XSTATE header and do a full restore which will put these cleared features into init state. There is no real difference in performance because the current code already does a full restore when the xfeatures bits are preserved as the signal frame setup has stored them, which is the full UABI feature set. Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov --- arch/x86/kernel/fpu/signal.c | 89 ++++++++++++++----------------------------- 1 file changed, 31 insertions(+), 58 deletions(-) --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -220,36 +220,6 @@ int copy_fpstate_to_sigframe(void __user return 0; } -static inline void -sanitize_restored_user_xstate(union fpregs_state *state, - struct user_i387_ia32_struct *ia32_env, u64 mask) -{ - struct xregs_state *xsave = &state->xsave; - struct xstate_header *header = &xsave->header; - - if (use_xsave()) { - /* - * Clear all feature bits which are not set in mask. - * - * Supervisor state has to be preserved. The sigframe - * restore can only modify user features, i.e. @mask - * cannot contain them. - */ - header->xfeatures &= mask | xfeatures_mask_supervisor(); - } - - if (use_fxsr()) { - /* - * mscsr reserved bits must be masked to zero for security - * reasons. - */ - xsave->i387.mxcsr &= mxcsr_feature_mask; - - if (ia32_env) - convert_to_fxsr(&state->fxsave, ia32_env); - } -} - static int __restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only) { @@ -352,6 +322,8 @@ static int __fpu_restore_sig(void __user fx_only = !fx_sw_user.magic1; state_size = fx_sw_user.xstate_size; user_xfeatures = fx_sw_user.xfeatures; + } else { + user_xfeatures = XFEATURE_MASK_FPSSE; } if (likely(!ia32_fxstate)) { @@ -395,54 +367,55 @@ static int __fpu_restore_sig(void __user set_thread_flag(TIF_NEED_FPU_LOAD); } __fpu_invalidate_fpregs_state(fpu); + __cpu_invalidate_fpregs_state(); fpregs_unlock(); if (use_xsave() && !fx_only) { - u64 init_bv = xfeatures_mask_uabi() & ~user_xfeatures; - ret = copy_sigframe_from_user_to_xstate(&fpu->state.xsave, buf_fx); if (ret) return ret; + } else { + if (__copy_from_user(&fpu->state.fxsave, buf_fx, + sizeof(fpu->state.fxsave))) + return -EFAULT; - sanitize_restored_user_xstate(&fpu->state, &env, user_xfeatures); + /* Reject invalid MXCSR values. */ + if (fpu->state.fxsave.mxcsr & mxcsr_feature_mask) + return -EINVAL; - fpregs_lock(); - if (unlikely(init_bv)) - os_xrstor(&init_fpstate.xsave, init_bv); + /* Enforce XFEATURE_MASK_FPSSE when XSAVE is enabled */ + if (use_xsave()) + fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_FPSSE; + } + + /* Fold the legacy FP storage */ + convert_to_fxsr(&fpu->state.fxsave, &env); + fpregs_lock(); + if (use_xsave()) { /* - * Restore previously saved supervisor xstates along with - * copied-in user xstates. + * Remove all UABI feature bits not set in user_xfeatures + * from the memory xstate header which makes the full + * restore below bring them into init state. This works for + * fx_only mode as well because that has only FP and SSE + * set in user_xfeatures. + * + * Preserve supervisor states! */ - ret = os_xrstor_safe(&fpu->state.xsave, - user_xfeatures | xfeatures_mask_supervisor()); + u64 mask = user_xfeatures | xfeatures_mask_supervisor(); + fpu->state.xsave.header.xfeatures &= mask; + ret = os_xrstor_safe(&fpu->state.xsave, xfeatures_mask_all); } else { - ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size); - if (ret) - return -EFAULT; - - sanitize_restored_user_xstate(&fpu->state, &env, user_xfeatures); - - fpregs_lock(); - if (use_xsave()) { - u64 init_bv; - - init_bv = xfeatures_mask_uabi() & ~XFEATURE_MASK_FPSSE; - os_xrstor(&init_fpstate.xsave, init_bv); - } - ret = fxrstor_safe(&fpu->state.fxsave); } - if (!ret) + if (likely(!ret)) fpregs_mark_activate(); - else - fpregs_deactivate(fpu); + fpregs_unlock(); return ret; } - static inline int xstate_sigframe_size(void) { return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :