From patchwork Tue Mar 7 14:25:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Asahi Lina X-Patchwork-Id: 661391 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7C2AC6FD1A for ; Tue, 7 Mar 2023 14:32:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230486AbjCGOcJ (ORCPT ); Tue, 7 Mar 2023 09:32:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229582AbjCGObZ (ORCPT ); Tue, 7 Mar 2023 09:31:25 -0500 Received: from mail.marcansoft.com (marcansoft.com [212.63.210.85]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36D478B064; Tue, 7 Mar 2023 06:27:12 -0800 (PST) Received: from [127.0.0.1] (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: linasend@asahilina.net) by mail.marcansoft.com (Postfix) with ESMTPSA id 1D5B642528; Tue, 7 Mar 2023 14:27:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=asahilina.net; s=default; t=1678199230; bh=F1SRAlKo7BSIaLQ7gj8v5YlQfBwivdnzeJ8qnwB97A4=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=jWGXNdok7booYlvp21MSywrjaBbrNPUOU0mT/8sAntEMvNSBysxntLc98cv75xdYX RCg5ekT5IfZ64CjaIwqYAHnRPzV0dg4ueuM5PywDJLOQXLV+mXp9ChItffn2Tw//mj IgoNtG0Ir/bLvMRfauIUURFSixaOirYJxf6Q967INfBaKJ/RJYBAMbCluh6QM/w1Yq HAUu4C9jJb4E1HshphKRyDPOn0poCGThNi7WvyL/qXF6/JXRrcXHLUDLfS+bNLh427 hd2mLg7zRccSoXkAo+kYOoFpHgWtQObypyS1+Rz7x8gmNGF2zunralOQU3+uKMn3x+ ch1YhPHtgI3ow== From: Asahi Lina Date: Tue, 07 Mar 2023 23:25:29 +0900 Subject: [PATCH RFC 04/18] rust: drm: gem: Add GEM object abstraction MIME-Version: 1.0 Message-Id: <20230307-rust-drm-v1-4-917ff5bc80a8@asahilina.net> References: <20230307-rust-drm-v1-0-917ff5bc80a8@asahilina.net> In-Reply-To: <20230307-rust-drm-v1-0-917ff5bc80a8@asahilina.net> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Luben Tuikov , Jarkko Sakkinen , Dave Hansen Cc: Alyssa Rosenzweig , Karol Herbst , Ella Stanforth , Faith Ekstrand , Mary , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-sgx@vger.kernel.org, asahi@lists.linux.dev, Asahi Lina X-Mailer: b4 0.12.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1678199191; l=16269; i=lina@asahilina.net; s=20230221; h=from:subject:message-id; bh=F1SRAlKo7BSIaLQ7gj8v5YlQfBwivdnzeJ8qnwB97A4=; b=nXvhHnuR0S4HW6xMU182DkD+eGloZ8eCqt3T0yyYFehUpkIdq6wh+Tsm/p0kPWP2XWtbmp6Ix ZKYhDt6DYHVBwLvs6pXLABRbM2g0wJ1QRbmnk+fGSuC5ChaB4x0OthD X-Developer-Key: i=lina@asahilina.net; a=ed25519; pk=Qn8jZuOtR1m5GaiDfTrAoQ4NE1XoYVZ/wmt5YtXWFC4= Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org The DRM GEM subsystem is the DRM memory management subsystem used by most modern drivers. Add a Rust abstraction to allow Rust DRM driver implementations to use it. Signed-off-by: Asahi Lina --- rust/bindings/bindings_helper.h | 1 + rust/helpers.c | 23 +++ rust/kernel/drm/drv.rs | 4 +- rust/kernel/drm/gem/mod.rs | 374 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/drm/mod.rs | 1 + 5 files changed, 401 insertions(+), 2 deletions(-) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 7d7828faf89c..7183dfe6473f 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers.c b/rust/helpers.c index 73b2ce607f27..78ec4162b03b 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -18,6 +18,7 @@ * accidentally exposed. */ +#include #include #include #include @@ -374,6 +375,28 @@ void rust_helper_init_completion(struct completion *c) } EXPORT_SYMBOL_GPL(rust_helper_init_completion); +#ifdef CONFIG_DRM + +void rust_helper_drm_gem_object_get(struct drm_gem_object *obj) +{ + drm_gem_object_get(obj); +} +EXPORT_SYMBOL_GPL(rust_helper_drm_gem_object_get); + +void rust_helper_drm_gem_object_put(struct drm_gem_object *obj) +{ + drm_gem_object_put(obj); +} +EXPORT_SYMBOL_GPL(rust_helper_drm_gem_object_put); + +__u64 rust_helper_drm_vma_node_offset_addr(struct drm_vma_offset_node *node) +{ + return drm_vma_node_offset_addr(node); +} +EXPORT_SYMBOL_GPL(rust_helper_drm_vma_node_offset_addr); + +#endif + /* * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type * as the Rust `usize` type, so we can use it in contexts where Rust diff --git a/rust/kernel/drm/drv.rs b/rust/kernel/drm/drv.rs index 1dcb651e1417..c138352cb489 100644 --- a/rust/kernel/drm/drv.rs +++ b/rust/kernel/drm/drv.rs @@ -126,7 +126,7 @@ pub struct AllocOps { } /// Trait for memory manager implementations. Implemented internally. -pub trait AllocImpl: Sealed { +pub trait AllocImpl: Sealed + drm::gem::IntoGEMObject { /// The C callback operations for this memory manager. const ALLOC_OPS: AllocOps; } @@ -263,7 +263,7 @@ impl Registration { drm, registered: false, vtable, - fops: Default::default(), // TODO: GEM abstraction + fops: drm::gem::create_fops(), _pin: PhantomPinned, _p: PhantomData, }) diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs new file mode 100644 index 000000000000..8a7d99613718 --- /dev/null +++ b/rust/kernel/drm/gem/mod.rs @@ -0,0 +1,374 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT + +//! DRM GEM API +//! +//! C header: [`include/linux/drm/drm_gem.h`](../../../../include/linux/drm/drm_gem.h) + +use alloc::boxed::Box; + +use crate::{ + bindings, + drm::{device, drv, file}, + error::{to_result, Result}, + prelude::*, +}; +use core::{mem, mem::ManuallyDrop, ops::Deref, ops::DerefMut}; + +/// GEM object functions, which must be implemented by drivers. +pub trait BaseDriverObject: Sync + Send + Sized { + /// Create a new driver data object for a GEM object of a given size. + fn new(dev: &device::Device, size: usize) -> Result; + + /// Open a new handle to an existing object, associated with a File. + fn open( + _obj: &<::Driver as drv::Driver>::Object, + _file: &file::File<<::Driver as drv::Driver>::File>, + ) -> Result { + Ok(()) + } + + /// Close a handle to an existing object, associated with a File. + fn close( + _obj: &<::Driver as drv::Driver>::Object, + _file: &file::File<<::Driver as drv::Driver>::File>, + ) { + } +} + +/// Trait that represents a GEM object subtype +pub trait IntoGEMObject: Sized + crate::private::Sealed { + /// Owning driver for this type + type Driver: drv::Driver; + + /// Returns a pointer to the raw `drm_gem_object` structure, which must be valid as long as + /// this owning object is valid. + fn gem_obj(&self) -> *mut bindings::drm_gem_object; + + /// Returns a reference to the raw `drm_gem_object` structure, which must be valid as long as + /// this owning object is valid. + fn gem_ref(&self) -> &bindings::drm_gem_object { + // SAFETY: gem_obj() must be valid per the above requirement. + unsafe { &*self.gem_obj() } + } + + /// Converts a pointer to a `drm_gem_object` into a pointer to this type. + fn from_gem_obj(obj: *mut bindings::drm_gem_object) -> *mut Self; +} + +/// Trait which must be implemented by drivers using base GEM objects. +pub trait DriverObject: BaseDriverObject> { + /// Parent `Driver` for this object. + type Driver: drv::Driver; +} + +unsafe extern "C" fn free_callback(obj: *mut bindings::drm_gem_object) { + // SAFETY: All of our objects are Object. + let this = crate::container_of!(obj, Object, obj) as *mut Object; + + // SAFETY: The pointer we got has to be valid + unsafe { bindings::drm_gem_object_release(obj) }; + + // SAFETY: All of our objects are allocated via Box<>, and we're in the + // free callback which guarantees this object has zero remaining references, + // so we can drop it + unsafe { Box::from_raw(this) }; +} + +unsafe extern "C" fn open_callback, U: BaseObject>( + raw_obj: *mut bindings::drm_gem_object, + raw_file: *mut bindings::drm_file, +) -> core::ffi::c_int { + // SAFETY: The pointer we got has to be valid. + let file = unsafe { + file::File::<<::Driver as drv::Driver>::File>::from_raw(raw_file) + }; + let obj = + <<::Driver as drv::Driver>::Object as IntoGEMObject>::from_gem_obj( + raw_obj, + ); + + // SAFETY: from_gem_obj() returns a valid pointer as long as the type is + // correct and the raw_obj we got is valid. + match T::open(unsafe { &*obj }, &file) { + Err(e) => e.to_kernel_errno(), + Ok(()) => 0, + } +} + +unsafe extern "C" fn close_callback, U: BaseObject>( + raw_obj: *mut bindings::drm_gem_object, + raw_file: *mut bindings::drm_file, +) { + // SAFETY: The pointer we got has to be valid. + let file = unsafe { + file::File::<<::Driver as drv::Driver>::File>::from_raw(raw_file) + }; + let obj = + <<::Driver as drv::Driver>::Object as IntoGEMObject>::from_gem_obj( + raw_obj, + ); + + // SAFETY: from_gem_obj() returns a valid pointer as long as the type is + // correct and the raw_obj we got is valid. + T::close(unsafe { &*obj }, &file); +} + +impl IntoGEMObject for Object { + type Driver = T::Driver; + + fn gem_obj(&self) -> *mut bindings::drm_gem_object { + &self.obj as *const _ as *mut _ + } + + fn from_gem_obj(obj: *mut bindings::drm_gem_object) -> *mut Object { + crate::container_of!(obj, Object, obj) as *mut Object + } +} + +/// Base operations shared by all GEM object classes +pub trait BaseObject: IntoGEMObject { + /// Returns the size of the object in bytes. + fn size(&self) -> usize { + self.gem_ref().size + } + + /// Creates a new reference to the object. + fn reference(&self) -> ObjectRef { + // SAFETY: Having a reference to an Object implies holding a GEM reference + unsafe { + bindings::drm_gem_object_get(self.gem_obj()); + } + ObjectRef { + ptr: self as *const _, + } + } + + /// Creates a new handle for the object associated with a given `File` + /// (or returns an existing one). + fn create_handle( + &self, + file: &file::File<<::Driver as drv::Driver>::File>, + ) -> Result { + let mut handle: u32 = 0; + // SAFETY: The arguments are all valid per the type invariants. + to_result(unsafe { + bindings::drm_gem_handle_create(file.raw() as *mut _, self.gem_obj(), &mut handle) + })?; + Ok(handle) + } + + /// Looks up an object by its handle for a given `File`. + fn lookup_handle( + file: &file::File<<::Driver as drv::Driver>::File>, + handle: u32, + ) -> Result> { + // SAFETY: The arguments are all valid per the type invariants. + let ptr = unsafe { bindings::drm_gem_object_lookup(file.raw() as *mut _, handle) }; + + if ptr.is_null() { + Err(ENOENT) + } else { + Ok(ObjectRef { + ptr: ptr as *const _, + }) + } + } + + /// Creates an mmap offset to map the object from userspace. + fn create_mmap_offset(&self) -> Result { + // SAFETY: The arguments are valid per the type invariant. + to_result(unsafe { + // TODO: is this threadsafe? + bindings::drm_gem_create_mmap_offset(self.gem_obj()) + })?; + Ok(unsafe { + bindings::drm_vma_node_offset_addr(&self.gem_ref().vma_node as *const _ as *mut _) + }) + } +} + +impl BaseObject for T {} + +/// A base GEM object. +#[repr(C)] +pub struct Object { + obj: bindings::drm_gem_object, + // The DRM core ensures the Device exists as long as its objects exist, so we don't need to + // manage the reference count here. + dev: ManuallyDrop>, + inner: T, +} + +impl Object { + /// The size of this object's structure. + pub const SIZE: usize = mem::size_of::(); + + const OBJECT_FUNCS: bindings::drm_gem_object_funcs = bindings::drm_gem_object_funcs { + free: Some(free_callback::), + open: Some(open_callback::>), + close: Some(close_callback::>), + print_info: None, + export: None, + pin: None, + unpin: None, + get_sg_table: None, + vmap: None, + vunmap: None, + mmap: None, + vm_ops: core::ptr::null_mut(), + }; + + /// Create a new GEM object. + pub fn new(dev: &device::Device, size: usize) -> Result> { + let mut obj: Box = Box::try_new(Self { + // SAFETY: This struct is expected to be zero-initialized + obj: unsafe { mem::zeroed() }, + // SAFETY: The drm subsystem guarantees that the drm_device will live as long as + // the GEM object lives, so we can conjure a reference out of thin air. + dev: ManuallyDrop::new(unsafe { device::Device::from_raw(dev.ptr) }), + inner: T::new(dev, size)?, + })?; + + obj.obj.funcs = &Self::OBJECT_FUNCS; + to_result(unsafe { + bindings::drm_gem_object_init(dev.raw() as *mut _, &mut obj.obj, size) + })?; + + let obj_ref = UniqueObjectRef { + ptr: Box::leak(obj), + }; + + Ok(obj_ref) + } + + /// Returns the `Device` that owns this GEM object. + pub fn dev(&self) -> &device::Device { + &self.dev + } +} + +impl crate::private::Sealed for Object {} + +impl Deref for Object { + type Target = T; + + fn deref(&self) -> &Self::Target { + &self.inner + } +} + +impl DerefMut for Object { + fn deref_mut(&mut self) -> &mut Self::Target { + &mut self.inner + } +} + +impl drv::AllocImpl for Object { + const ALLOC_OPS: drv::AllocOps = drv::AllocOps { + gem_create_object: None, + prime_handle_to_fd: Some(bindings::drm_gem_prime_handle_to_fd), + prime_fd_to_handle: Some(bindings::drm_gem_prime_fd_to_handle), + gem_prime_import: None, + gem_prime_import_sg_table: None, + gem_prime_mmap: Some(bindings::drm_gem_prime_mmap), + dumb_create: None, + dumb_map_offset: None, + dumb_destroy: None, + }; +} + +/// A reference-counted shared reference to a base GEM object. +pub struct ObjectRef { + // Invariant: the pointer is valid and initialized, and this ObjectRef owns a reference to it. + ptr: *const T, +} + +/// SAFETY: GEM object references are safe to share between threads. +unsafe impl Send for ObjectRef {} +unsafe impl Sync for ObjectRef {} + +impl Clone for ObjectRef { + fn clone(&self) -> Self { + self.reference() + } +} + +impl Drop for ObjectRef { + fn drop(&mut self) { + // SAFETY: Having an ObjectRef implies holding a GEM reference. + // The free callback will take care of deallocation. + unsafe { + bindings::drm_gem_object_put((*self.ptr).gem_obj()); + } + } +} + +impl Deref for ObjectRef { + type Target = T; + + fn deref(&self) -> &Self::Target { + // SAFETY: The pointer is valid per the invariant + unsafe { &*self.ptr } + } +} + +/// A unique reference to a base GEM object. +pub struct UniqueObjectRef { + // Invariant: the pointer is valid and initialized, and this ObjectRef owns the only reference + // to it. + ptr: *mut T, +} + +impl UniqueObjectRef { + /// Downgrade this reference to a shared reference. + pub fn into_ref(self) -> ObjectRef { + let ptr = self.ptr as *const _; + core::mem::forget(self); + + ObjectRef { ptr } + } +} + +impl Drop for UniqueObjectRef { + fn drop(&mut self) { + // SAFETY: Having a UniqueObjectRef implies holding a GEM + // reference. The free callback will take care of deallocation. + unsafe { + bindings::drm_gem_object_put((*self.ptr).gem_obj()); + } + } +} + +impl Deref for UniqueObjectRef { + type Target = T; + + fn deref(&self) -> &Self::Target { + // SAFETY: The pointer is valid per the invariant + unsafe { &*self.ptr } + } +} + +impl DerefMut for UniqueObjectRef { + fn deref_mut(&mut self) -> &mut Self::Target { + // SAFETY: The pointer is valid per the invariant + unsafe { &mut *self.ptr } + } +} + +pub(super) fn create_fops() -> bindings::file_operations { + bindings::file_operations { + owner: core::ptr::null_mut(), + open: Some(bindings::drm_open), + release: Some(bindings::drm_release), + unlocked_ioctl: Some(bindings::drm_ioctl), + #[cfg(CONFIG_COMPAT)] + compat_ioctl: Some(bindings::drm_compat_ioctl), + #[cfg(not(CONFIG_COMPAT))] + compat_ioctl: None, + poll: Some(bindings::drm_poll), + read: Some(bindings::drm_read), + llseek: Some(bindings::noop_llseek), + mmap: Some(bindings::drm_gem_mmap), + ..Default::default() + } +} diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs index a767942d0b52..c44760a1332f 100644 --- a/rust/kernel/drm/mod.rs +++ b/rust/kernel/drm/mod.rs @@ -5,4 +5,5 @@ pub mod device; pub mod drv; pub mod file; +pub mod gem; pub mod ioctl;