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 CFBAAC433F5 for ; Tue, 26 Oct 2021 16:17:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B74FE60F0F for ; Tue, 26 Oct 2021 16:17:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237573AbhJZQTt (ORCPT ); Tue, 26 Oct 2021 12:19:49 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:34616 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237353AbhJZQTJ (ORCPT ); Tue, 26 Oct 2021 12:19:09 -0400 Date: Tue, 26 Oct 2021 16:16:42 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1635265003; h=from:from:sender:sender:reply-to: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: in-reply-to:in-reply-to:references:references; bh=IAirAetsHHT1nRztU70EB/5VLugxerIjwwBZu4dffbM=; b=2oOg5kwyFAsBzakwvzcN8nwbwl14jJs5WtNdixQMEiWVDHZkUgQBc1N2tWoZY7rFjLBQ/r ywg7eXjm9c+KZpa0q73oPDauZRqFeOOjKamIlmZrZKEVOq/tgOkn7F4a8oGZe5ZEt27iOo GDXz4apJtzw1u+CRgyS0xdN+zjJrNifiorLY5v3O5Ch12AaXF2hLA0M9eLBDKKAF1m8h7I 5GAioJaf6oG3mJcZty6tiV3vqzzg6RrvcUQkormqpgnPlDpJ6QkfEzM6UI5U8/+4hYrOPV h2lJ0Rt7bkxCGf0gfukFEDcy7rCVScI9J3fhKUiAYA4t6blFl+QpWRCFoam0wg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1635265003; h=from:from:sender:sender:reply-to: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: in-reply-to:in-reply-to:references:references; bh=IAirAetsHHT1nRztU70EB/5VLugxerIjwwBZu4dffbM=; b=zB3iL4CaNYW7Gq4V8FriHb2XgeDYE43Qn+Oh7jt+qkcvHrAk6/2h8V6aecbcZ4rEaFZeur etiaM04JKmPWzUDw== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/fpu] x86/fpu: Prepare fpu_clone() for dynamically enabled features Cc: Thomas Gleixner , "Chang S. Bae" , Borislav Petkov , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20211021225527.10184-11-chang.seok.bae@intel.com> References: <20211021225527.10184-11-chang.seok.bae@intel.com> MIME-Version: 1.0 Message-ID: <163526500273.626.12198381538366775281.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/fpu branch of tip: Commit-ID: 9e798e9aa14c45fb94e47b30bf6347b369ce9df7 Gitweb: https://git.kernel.org/tip/9e798e9aa14c45fb94e47b30bf6347b369ce9df7 Author: Thomas Gleixner AuthorDate: Thu, 21 Oct 2021 15:55:14 -07:00 Committer: Borislav Petkov CommitterDate: Tue, 26 Oct 2021 10:18:09 +02:00 x86/fpu: Prepare fpu_clone() for dynamically enabled features The default portion of the parent's FPU state is saved in a child task. With dynamic features enabled, the non-default portion is not saved in a child's fpstate because these register states are defined to be caller-saved. The new task's fpstate is therefore the default buffer. Fork inherits the permission of the parent. Also, do not use memcpy() when TIF_NEED_FPU_LOAD is set because it is invalid when the parent has dynamic features. Signed-off-by: Thomas Gleixner Signed-off-by: Chang S. Bae Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211021225527.10184-11-chang.seok.bae@intel.com --- arch/x86/include/asm/fpu/sched.h | 2 +- arch/x86/kernel/fpu/core.c | 35 ++++++++++++++++++++++--------- arch/x86/kernel/process.c | 2 +- 3 files changed, 27 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/fpu/sched.h b/arch/x86/include/asm/fpu/sched.h index cdb78d5..99a8820 100644 --- a/arch/x86/include/asm/fpu/sched.h +++ b/arch/x86/include/asm/fpu/sched.h @@ -11,7 +11,7 @@ extern void save_fpregs_to_fpstate(struct fpu *fpu); extern void fpu__drop(struct fpu *fpu); -extern int fpu_clone(struct task_struct *dst); +extern int fpu_clone(struct task_struct *dst, unsigned long clone_flags); extern void fpu_flush_thread(void); /* diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 4018083..1ff6b83 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -423,8 +423,20 @@ void fpstate_reset(struct fpu *fpu) fpu->perm.__user_state_size = fpu_user_cfg.default_size; } +static inline void fpu_inherit_perms(struct fpu *dst_fpu) +{ + if (fpu_state_size_dynamic()) { + struct fpu *src_fpu = ¤t->group_leader->thread.fpu; + + spin_lock_irq(¤t->sighand->siglock); + /* Fork also inherits the permissions of the parent */ + dst_fpu->perm = src_fpu->perm; + spin_unlock_irq(¤t->sighand->siglock); + } +} + /* Clone current's FPU state on fork */ -int fpu_clone(struct task_struct *dst) +int fpu_clone(struct task_struct *dst, unsigned long clone_flags) { struct fpu *src_fpu = ¤t->thread.fpu; struct fpu *dst_fpu = &dst->thread.fpu; @@ -455,17 +467,20 @@ int fpu_clone(struct task_struct *dst) } /* - * If the FPU registers are not owned by current just memcpy() the - * state. Otherwise save the FPU registers directly into the - * child's FPU context, without any memory-to-memory copying. + * Save the default portion of the current FPU state into the + * clone. Assume all dynamic features to be defined as caller- + * saved, which enables skipping both the expansion of fpstate + * and the copying of any dynamic state. + * + * Do not use memcpy() when TIF_NEED_FPU_LOAD is set because + * copying is not valid when current uses non-default states. */ fpregs_lock(); - if (test_thread_flag(TIF_NEED_FPU_LOAD)) { - memcpy(&dst_fpu->fpstate->regs, &src_fpu->fpstate->regs, - dst_fpu->fpstate->size); - } else { - save_fpregs_to_fpstate(dst_fpu); - } + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + fpregs_restore_userregs(); + save_fpregs_to_fpstate(dst_fpu); + if (!(clone_flags & CLONE_THREAD)) + fpu_inherit_perms(dst_fpu); fpregs_unlock(); trace_x86_fpu_copy_src(src_fpu); diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 97fea16..99025e3 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -157,7 +157,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, frame->flags = X86_EFLAGS_FIXED; #endif - fpu_clone(p); + fpu_clone(p, clone_flags); /* Kernel thread ? */ if (unlikely(p->flags & PF_KTHREAD)) {