From nobody Wed Feb 5 21:54:53 2025 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (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 942F71DBB3A; Thu, 16 Jan 2025 13:05:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737032732; cv=pass; b=KCjO1RvyxR2NCQANEDL6sYE525KV8prTAIIQp83he9D75mv/AKclDczQDZhrwF7W6Ds34aUyi0HY4Km6MWjC5vqWZGeAiiICWecIzB7ODMZ+njdhB7UyG/AWMN506z/GAga/N2RJervG2/GpWrp3OQLIwM/dUKJV4GP1nzBlAeI= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737032732; c=relaxed/simple; bh=wVsYSFfTcq4Qyi8hxT3KVJPP/YjMXtye28uMP3CXwbA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ik87epVCJ3fXDwXQzoZ9yPi7IIsTV0BLZFhGRef4eDC4JBbgS6SsLrKZVxIrFK0840/kHIYuiQkfMqzjc1YAymLyZSkn31EPv2vTFBHEeACjfUy87gy6BqYMFHVoqnAYEgIiA3uAh+HeWBRD/65ZisgfOGHrat0+XhL13JibRfg= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=daniel.almeida@collabora.com header.b=F1vygAB2; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=daniel.almeida@collabora.com header.b="F1vygAB2" ARC-Seal: i=1; a=rsa-sha256; t=1737032715; cv=none; d=zohomail.com; s=zohoarc; b=aZZIBOvnde6HoJEawyZAaZ0F7UUQY3WmIYfczA5wA2YjlHut2nT7U3vTWtYgktyz6dnNBIuSIbRFKhjGf5b8yUIBc0qqbl2K/qqRFo09RUzeTcmRgy0OCyViE7P5L7+gZWjQN2UlRkCx8m4N77S2d4yDnke+QU5TGK/mWEA96sU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1737032715; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=gLNt5hpMp+JnNu9GS+NNBAUe84OPwFhj4SDFgzDn6+A=; b=WX0Z7PsMsPqtP0G/2i5LYwidgfUpPl4XLLgNCBO4DpEF/+AfAy5poC77QCVCfGItvwfA+ZgZFF4ov8NrZ1Z0OWLr/REkf3dr2w3DpuVTPx/VbHSYoLJIFeDdoe9EVa0Xb9VChGgO3fhAaZXa7OiM78fMcjYVdFrCS4YMAp6pWas= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=daniel.almeida@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1737032715; s=zohomail; d=collabora.com; i=daniel.almeida@collabora.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=gLNt5hpMp+JnNu9GS+NNBAUe84OPwFhj4SDFgzDn6+A=; b=F1vygAB2FgR109i2zfiTbO9Qj3PUjGVbyfT4nNkRnWXVIIKu9ouQlw6F7rZvKUVj nVFqvsKpDU8sLePkJM57EtKlvRXstoVxFfjdpFTitsCwfXNTXFJrItJh+yfdqOwDuTb w2h4PvEOyO0zojA0M5MkYfLw8JvDeTc2ujPcAE3w= Received: by mx.zohomail.com with SMTPS id 1737032713507931.9572553428109; Thu, 16 Jan 2025 05:05:13 -0800 (PST) From: Daniel Almeida To: ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.mco, benno.lossin@proton.me, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, boris.brezillon@collabora.com, robh@kernel.org Cc: Daniel Almeida , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH RESEND v5 2/3] rust: io: mem: add a generic iomem abstraction Date: Thu, 16 Jan 2025 09:56:25 -0300 Message-ID: <20250116125632.65017-3-daniel.almeida@collabora.com> X-Mailer: git-send-email 2.48.0 In-Reply-To: <20250116125632.65017-1-daniel.almeida@collabora.com> References: <20250116125632.65017-1-daniel.almeida@collabora.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External Content-Type: text/plain; charset="utf-8" Add a generic iomem abstraction to safely read and write ioremapped regions. The reads and writes are done through IoRaw, and are thus checked either at compile-time, if the size of the region is known at that point, or at runtime otherwise. Non-exclusive access to the underlying memory region is made possible to cater to cases where overlapped regions are unavoidable. Signed-off-by: Daniel Almeida --- rust/helpers/io.c | 10 +++++ rust/kernel/io.rs | 1 + rust/kernel/io/mem.rs | 98 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 109 insertions(+) create mode 100644 rust/kernel/io/mem.rs diff --git a/rust/helpers/io.c b/rust/helpers/io.c index 3cb47bd01942..cb10060c08ae 100644 --- a/rust/helpers/io.c +++ b/rust/helpers/io.c @@ -106,3 +106,13 @@ resource_size_t rust_helper_resource_size(struct resou= rce *res) return resource_size(res); } =20 +struct resource *rust_helper_request_mem_region(resource_size_t start, res= ource_size_t n, + const char *name) +{ + return request_mem_region(start, n, name); +} + +void rust_helper_release_mem_region(resource_size_t start, resource_size_t= n) +{ + release_mem_region(start, n); +} diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs index 566d8b177e01..9ce3482b5ecd 100644 --- a/rust/kernel/io.rs +++ b/rust/kernel/io.rs @@ -7,6 +7,7 @@ use crate::error::{code::EINVAL, Result}; use crate::{bindings, build_assert}; =20 +pub mod mem; pub mod resource; =20 /// Raw representation of an MMIO region. diff --git a/rust/kernel/io/mem.rs b/rust/kernel/io/mem.rs new file mode 100644 index 000000000000..a287dc0898e0 --- /dev/null +++ b/rust/kernel/io/mem.rs @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Generic memory-mapped IO. + +use core::ops::Deref; + +use crate::device::Device; +use crate::devres::Devres; +use crate::io::resource::Resource; +use crate::io::Io; +use crate::io::IoRaw; +use crate::prelude::*; + +/// A generic memory-mapped IO region. +/// +/// Accesses to the underlying region is checked either at compile time, i= f the +/// region's size is known at that point, or at runtime otherwise. +/// +/// Whether `IoMem` represents an exclusive access to the underlying memory +/// region is determined by the caller at creation time, as overlapping ac= cess +/// may be needed in some cases. +/// +/// # Invariants +/// +/// `IoMem` always holds an `IoRaw` inststance that holds a valid pointer = to the +/// start of the I/O memory mapped region. +pub struct IoMem { + io: IoRaw, + res_start: u64, +} + +impl IoMem { + /// Creates a new `IoMem` instance. + pub(crate) fn new(resource: &Resource, device: &Device) -> Result> { + let size =3D resource.size(); + if size =3D=3D 0 { + return Err(EINVAL); + } + + let res_start =3D resource.start(); + + if EXCLUSIVE { + // SAFETY: + // - `res_start` and `size` are read from a presumably valid `= struct resource`. + // - `size` is known not to be zero at this point. + // - `resource.name()` returns a valid C string. + let mem_region =3D unsafe { + bindings::request_mem_region(res_start, size, resource.nam= e().as_char_ptr()) + }; + + if mem_region.is_null() { + return Err(EBUSY); + } + } + + // SAFETY: + // - `res_start` and `size` are read from a presumably valid `stru= ct resource`. + // - `size` is known not to be zero at this point. + let addr =3D unsafe { bindings::ioremap(res_start, size as kernel:= :ffi::c_ulong) }; + if addr.is_null() { + if EXCLUSIVE { + // SAFETY: + // - `res_start` and `size` are read from a presumably val= id `struct resource`. + // - `size` is the same as the one passed to `request_mem_= region`. + unsafe { bindings::release_mem_region(res_start, size) }; + } + return Err(ENOMEM); + } + + let io =3D IoRaw::new(addr as usize, size as usize)?; + let io =3D IoMem { io, res_start }; + let devres =3D Devres::new(device, io, GFP_KERNEL)?; + + Ok(devres) + } +} + +impl Drop for IoMem { + fn drop(&mut self) { + if EXCLUSIVE { + // SAFETY: `res_start` and `io.maxsize()` were the values pass= ed to + // `request_mem_region`. + unsafe { bindings::release_mem_region(self.res_start, self.io.= maxsize() as u64) } + } + + // SAFETY: Safe as by the invariant of `Io`. + unsafe { bindings::iounmap(self.io.addr() as *mut core::ffi::c_voi= d) } + } +} + +impl Deref for IoMem { + type Target =3D Io; + + fn deref(&self) -> &Self::Target { + // SAFETY: Safe as by the invariant of `IoMem`. + unsafe { Io::from_raw(&self.io) } + } +} --=20 2.48.0