From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0592613D8A8 for ; Thu, 25 Jul 2024 22:28:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721946533; cv=none; b=I8PAqu4du94w5KBwbnFNksNR9ArfDtFlaoPimL3DODvqRK/LMGnDLneKxuoSsHqabMZxLpZ/OdhZKpq2gVHG0Jhz2sm8lKQ2lw+bV9jxE5lWLMwg9dtM6zB18AmaEHrZWExR7mC9wok9H1sVQGfojIMQcIi1VNR2Tp5YpDSzJD4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721946533; c=relaxed/simple; bh=6poooE4/Vj63Q++XdjL9Rrlv4VS/Q9OIkaJPfz+S9i4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=uLoQucyT/HeMQoNIh+PB9quFNk6TU8dUuqj0k/r8Ec1MHds7GCzEvak7cjgbN8ZmdYB7p0aFrqifs9PEjiYk15I1lnABWaiB/9aAmjPFSY9r1Yb2Kba2r85F3GbI3eZVrQyR569bUsxEkSVOKSHJ7tFzhrN4HTD54WPAeeGuJpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=erzXmusx; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="erzXmusx" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1721946531; 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: in-reply-to:in-reply-to:references:references; bh=bvHSNNVvGvStasuVppfgiU1uxdltPfci54gfrkbDQh8=; b=erzXmusxOaPhndBtct7z425Bvc27fv1smoQpy6oGnXCfTQFaNDwVPdYvW3Rby98CGzzFsD qs5l3ybBxR4KK29qiCdTW0gmMOnGBLuUnIU/C9tszcyzqPmBFogXSVWydZBIL8cP0bt0kF X4PwaGHqhkbcAJOTuddkrQSgIQE3I8Y= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-167-yywUgwz_P8mgc4wboyZNaA-1; Thu, 25 Jul 2024 18:28:47 -0400 X-MC-Unique: yywUgwz_P8mgc4wboyZNaA-1 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1CA4019560B6; Thu, 25 Jul 2024 22:28:45 +0000 (UTC) Received: from emerald.lyude.net (unknown [10.22.33.21]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id C09E03000194; Thu, 25 Jul 2024 22:28:39 +0000 (UTC) From: Lyude Paul To: rust-for-linux@vger.kernel.org Cc: Danilo Krummrich , airlied@redhat.com, Ingo Molnar , Will Deacon , Waiman Long , Peter Zijlstra , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Martin Rodriguez Reboredo , FUJITA Tomonori , Aakash Sen Sharma , Valentin Obst , linux-kernel@vger.kernel.org (open list) Subject: [PATCH 1/3] rust: Introduce irq module Date: Thu, 25 Jul 2024 18:27:50 -0400 Message-ID: <20240725222822.1784931-2-lyude@redhat.com> In-Reply-To: <20240725222822.1784931-1-lyude@redhat.com> References: <20240725222822.1784931-1-lyude@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 This introduces a module for dealing with interrupt-disabled contexts, including the ability to enable and disable interrupts (with_irqs_disabled()) - along with the ability to annotate functions as expecting that IRQs are already disabled on the local CPU. Signed-off-by: Lyude Paul --- rust/helpers.c | 14 +++++++++ rust/kernel/irq.rs | 74 ++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 3 files changed, 89 insertions(+) create mode 100644 rust/kernel/irq.rs diff --git a/rust/helpers.c b/rust/helpers.c index 87ed0a5b60990..12ac32de820b5 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -69,6 +69,20 @@ void rust_helper_spin_unlock(spinlock_t *lock) } EXPORT_SYMBOL_GPL(rust_helper_spin_unlock); +unsigned long rust_helper_local_irq_save(void) { + unsigned long flags; + + local_irq_save(flags); + + return flags; +} +EXPORT_SYMBOL_GPL(rust_helper_local_irq_save); + +void rust_helper_local_irq_restore(unsigned long flags) { + local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(rust_helper_local_irq_restore); + void rust_helper_init_wait(struct wait_queue_entry *wq_entry) { init_wait(wq_entry); diff --git a/rust/kernel/irq.rs b/rust/kernel/irq.rs new file mode 100644 index 0000000000000..8a540bd6123f7 --- /dev/null +++ b/rust/kernel/irq.rs @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Interrupt controls +//! +//! This module allows Rust code to control processor interrupts. [`with_irqs_disabled()`] may be +//! used for nested disables of interrupts, whereas [`IrqDisabled`] can be used for annotating code +//! that requires that interrupts already be disabled. + +use bindings; +use core::marker::*; + +/// A guarantee that IRQs are disabled on this CPU +/// +/// An [`IrqDisabled`] represents a guarantee that interrupts will remain disabled on the current CPU +/// until the lifetime of the object ends. However, it does not disable or enable interrupts on its +/// own - see [`with_irqs_disabled()`] for that. +/// +/// This object has no cost at runtime (TODO: …except if whatever kernel compile-time option that +/// would assert IRQs are enabled or not is enabled - in which case we should actually verify that +/// they're enabled). +/// +/// # Examples +/// +/// If you want to ensure that a function may only be invoked within contexts where interrupts are +/// disabled, you can do so by requiring that a reference to this type be passed. You can also +/// create this type using unsafe code in order to indicate that it's known that interrupts are +/// already disabled on this CPU +/// +/// ``` +/// use kernel::irq::{IrqDisabled, disable_irqs}; +/// +/// // Requiring interrupts be disabled to call a function +/// fn dont_interrupt_me(_irq: &IrqDisabled<'_>) { } +/// +/// // Disabling interrupts. They'll be re-enabled once this closure completes. +/// disable_irqs(|irq| dont_interrupt_me(&irq)); +/// ``` +pub struct IrqDisabled<'a>(PhantomData<&'a ()>); + +impl<'a> IrqDisabled<'a> { + /// Create a new [`IrqDisabled`] without disabling interrupts + /// + /// If debug assertions are enabled, this function will check that interrupts are disabled. + /// Otherwise, it has no cost at runtime. + /// + /// # Safety + /// + /// This function must only be called in contexts where it is already known that interrupts have + /// been disabled for the current CPU, as the user is making a promise that they will remain + /// disabled at least until this [`IrqDisabled`] is dropped. + pub unsafe fn new() -> Self { + Self(PhantomData) + } +} + +/// Run the closure `cb` with interrupts disabled on the local CPU. +/// +/// Interrupts will be re-enabled once the closure returns. If interrupts were already disabled on +/// this CPU, this is a no-op. +#[inline] +pub fn with_irqs_disabled(cb: F) -> T +where + F: FnOnce(IrqDisabled<'_>) -> T, +{ + // SAFETY: FFI call with no special requirements + let flags = unsafe { bindings::local_irq_save() }; + + let ret = cb(IrqDisabled(PhantomData)); + + // SAFETY: `flags` comes from our previous call to local_irq_save + unsafe { bindings::local_irq_restore(flags) }; + + ret +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index e6b7d3a80bbce..37835ccd51087 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -36,6 +36,7 @@ pub mod firmware; pub mod init; pub mod ioctl; +pub mod irq; #[cfg(CONFIG_KUNIT)] pub mod kunit; #[cfg(CONFIG_NET)] -- 2.45.2