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,URIBL_BLOCKED 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 CA774C48BE8 for ; Fri, 18 Jun 2021 15:25:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1F7860FEE for ; Fri, 18 Jun 2021 15:25:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235466AbhFRP2D (ORCPT ); Fri, 18 Jun 2021 11:28:03 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:56806 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235096AbhFRPXc (ORCPT ); Fri, 18 Jun 2021 11:23:32 -0400 Message-Id: <20210618143451.562513044@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624029636; 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=VZiuaoMbQ+lzqJwpZe0a5HWgeLQ11vhAT7QIjiwbrM8=; b=iHDd11WTYa4CYXD+7v84OP4hEE4XqiVvG71+VP8pP1jzIRt5/hqC3MkzHVYYjM7CqZ4yrW +gv+mfQaZCGVJTzfkih3gseEGYJugXg09jgMVa4MeX1MytFuX6my+FKY9uL6VVGG+zOQtt wdHCBQPSjYk/TON2rjFVVG5ffcDD/ptHC6r7JJpz+vsWDgkjHoYI+vO7xCBSQwcNaOIWyY L/V0MCpdFm2V7PHURvSbNXkswc7WBsCdYotjUeUFzz3IoLGJdS0mqyJCDEnb2hnomUGGQX 54o4FGYYTjj2iI5CCMj0IQNw2SJedNCYFqxILeNXisOekQfuwL6HlXxj/5m1JA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624029636; 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=VZiuaoMbQ+lzqJwpZe0a5HWgeLQ11vhAT7QIjiwbrM8=; b=genUUa3Fsj49yDuh9kkSvgk+6va3VGbezrBDrhfbp3bdobBJtU8tAOeR2Rah06avNtxFqr L3X220xl3muCEzAA== Date: Fri, 18 Jun 2021 16:19:26 +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 Subject: [patch V3 63/66] x86/fpu/signal: Split out the direct restore code References: <20210618141823.161158090@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 Prepare for smarter failure handling of the direct restore. Signed-off-by: Thomas Gleixner --- arch/x86/kernel/fpu/signal.c | 110 +++++++++++++++++++++---------------------- 1 file changed, 56 insertions(+), 54 deletions(-) --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -249,10 +249,7 @@ sanitize_restored_user_xstate(union fpre } } -/* - * Restore the FPU state directly from the userspace signal frame. - */ -static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only) +static int restore_hwregs_from_user(void __user *buf, u64 xrestore, bool fx_only) { if (use_xsave()) { u64 init_bv = xfeatures_mask_uabi() & ~xrestore; @@ -273,6 +270,56 @@ static int restore_fpregs_from_user(void } } +static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only) +{ + struct fpu *fpu = ¤t->thread.fpu; + int ret ; + + fpregs_lock(); + pagefault_disable(); + ret = restore_hwregs_from_user(buf, xrestore, fx_only); + pagefault_enable(); + + if (unlikely(ret)) { + /* + * The above did an FPU restore operation, restricted to + * the user portion of the registers, and failed, but the + * microcode might have modified the FPU registers + * nevertheless. + * + * If the FPU registers do not belong to current, then + * invalidate the FPU register state otherwise the task + * might preempt current and return to user space with + * corrupted FPU registers. + * + * In case current owns the FPU registers then no further + * action is required. The fixup in the slow path will + * handle it correctly. + */ + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + __cpu_invalidate_fpregs_state(); + fpregs_unlock(); + return ret; + } + + /* + * Restore supervisor states: previous context switch etc has done + * XSAVES and saved the supervisor states in the kernel buffer from + * which they can be restored now. + * + * We cannot do a single XRSTORS here - which would be nice - + * because the rest of the FPU registers are being restored from a + * user buffer directly. The single XRSTORS happens below, when the + * user buffer has been copied to the kernel one. + */ + if (test_thread_flag(TIF_NEED_FPU_LOAD) && xfeatures_mask_supervisor()) + os_xrstor(&fpu->state.xsave, xfeatures_mask_supervisor()); + + fpregs_mark_activate(); + fpregs_unlock(); + return 0; +} + static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, bool ia32_fxstate) { @@ -297,61 +344,16 @@ static int __fpu_restore_sig(void __user user_xfeatures = fx_sw_user.xfeatures; } - if (!ia32_fxstate) { + if (likely(!ia32_fxstate)) { /* * Attempt to restore the FPU registers directly from user - * memory. For that to succeed, the user access cannot cause - * page faults. If it does, fall back to the slow path below, - * going through the kernel buffer with the enabled pagefault - * handler. + * memory. For that to succeed, the user access cannot cause page + * faults. If it does, fall back to the slow path below, going + * through the kernel buffer with the enabled pagefault handler. */ - fpregs_lock(); - pagefault_disable(); ret = restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only); - pagefault_enable(); - if (!ret) { - - /* - * Restore supervisor states: previous context switch - * etc has done XSAVES and saved the supervisor states - * in the kernel buffer from which they can be restored - * now. - * - * We cannot do a single XRSTORS here - which would - * be nice - because the rest of the FPU registers are - * being restored from a user buffer directly. The - * single XRSTORS happens below, when the user buffer - * has been copied to the kernel one. - */ - if (test_thread_flag(TIF_NEED_FPU_LOAD) && - xfeatures_mask_supervisor()) { - os_xrstor(&fpu->state.xsave, - xfeatures_mask_supervisor()); - } - fpregs_mark_activate(); - fpregs_unlock(); + if (likely(!ret)) return 0; - } - - /* - * The above did an FPU restore operation, restricted to - * the user portion of the registers, and failed, but the - * microcode might have modified the FPU registers - * nevertheless. - * - * If the FPU registers do not belong to current, then - * invalidate the FPU register state otherwise the task might - * preempt current and return to user space with corrupted - * FPU registers. - * - * In case current owns the FPU registers then no further - * action is required. The fixup below will handle it - * correctly. - */ - if (test_thread_flag(TIF_NEED_FPU_LOAD)) - __cpu_invalidate_fpregs_state(); - - fpregs_unlock(); } else { /* * For 32-bit frames with fxstate, copy the fxstate so it can