From patchwork Wed Sep 11 22:52:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Danilo Krummrich X-Patchwork-Id: 13801177 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E584EE57DC for ; Wed, 11 Sep 2024 22:55:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 998F36B0092; Wed, 11 Sep 2024 18:55:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 921AA6B0093; Wed, 11 Sep 2024 18:55:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7C1A26B0095; Wed, 11 Sep 2024 18:55:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 5C8396B0092 for ; 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Wed, 11 Sep 2024 22:55:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E35FC4CEC5; Wed, 11 Sep 2024 22:55:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726095322; bh=lbiLQnErRGDrQbj4pxfkEOD42vZ0I0vTG1uGJ1op8G0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g/+6QwRqD1gJeXD0nTRAi39kPwchUeku9kzbofccjkCxU8yKJ5xJQ9NbBWGzIY1J7 9bJDgYS9aUM5Kt1EmpIupw1BwMb8FinYpT9XninnRN7iEZEWbNW2TysnpXm+OukEZx ZuZ/IbeVMnIEZXNXgxVoCjP1tM91eAhZrdpDSq0CRNFAv/gKPqJs/6WbtW0xrFEJOs pr8NENuo8oo+1kjNBNQeVnArUGCnEjf4wxB+KRDyGNa17RP0LqHvduThVsdqPJMDLT x9NQtar2HyN8X5z4mqq6zfCPrH6DElkh9WCtMtjG8kcWiEEs/UhfpS/gCeJYmZxwoK Q2wE3EZLWULFA== From: Danilo Krummrich To: ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@samsung.com, aliceryhl@google.com, akpm@linux-foundation.org Cc: daniel.almeida@collabora.com, faith.ekstrand@collabora.com, boris.brezillon@collabora.com, lina@asahilina.net, mcanal@igalia.com, zhiw@nvidia.com, cjia@nvidia.com, jhubbard@nvidia.com, airlied@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-mm@kvack.org, Danilo Krummrich Subject: [PATCH v7 04/26] rust: alloc: implement `Allocator` for `Kmalloc` Date: Thu, 12 Sep 2024 00:52:40 +0200 Message-ID: <20240911225449.152928-5-dakr@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240911225449.152928-1-dakr@kernel.org> References: <20240911225449.152928-1-dakr@kernel.org> MIME-Version: 1.0 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6B69B1C0004 X-Stat-Signature: we7qfjfwmz9nmusz8a47wdy36c5o75mx X-Rspam-User: X-HE-Tag: 1726095323-634979 X-HE-Meta: U2FsdGVkX18Qj4+slumM4rcZ7R5bVR1Wxla3cWdmPkjGDeu2cXp4nB1kvS0ge51WRP1G6a8dAty/drV95WJdu8F7NXbh+NmpDTyg6dDNEdKNEgFZx7COdNZlDZozkCk2vHCV8Y3KuMbRv02ityvUnczNa/Yj4j9chaNSmH7tZnXhEEMBAXHKzJ7swR2klpZW/VCv3+HpJz5T7Og8N0EMQom6n23u6P8fpXhjQpeJvolEA1GnUAF4qUbkbIv7GIx9CSgX1f+hBGuy4ipqCx1aP8Zy5K7sLUc/CnrhBgXODrQJ0JStpWAVaMX02sDkIA1AyMMIrQ8DhSIW3Rzwa+fpiBxm//TruIS+acXLrt8nqWHyhECHgH+2a62Fu5s8URCAYMYWt4Ab00qbV4kDEfdf5PeNR/XmvEez/brgxQTcd1uLxQMEALwqXGwgibyOolTulvgjRi+E7z0N1RUcn/RPd9h1d07s59vtBTnAd56NcUvBdrTgvOZmPoTneoH7Qhi7O7ZUFrj1ybC/+FQC96oEDq933sLBq0P7ks8S6cucnHxPdizvEWQlPHp6WRrGfsX+xEyzoOS4mpKQEq3MGV7QBXbBxjQ7Fo94FFjF6D4kUJ87nC3zXUR3v3DKA1f8/jJjhFCbi4gLG+xkNwtHaYUNXizHowR68BROijYYGgZcx3hCmg3mpxV634oH1CAim3ek3N2QL7CibuF2NONvXV4Z8pKhjDPsv3Ep+L6uHJGJO3yjjRAxpS2hNRo229TMKfI+9FF6H1T8rJCCzcY2/MuIKnhWpS7JlfsgknH3K/GqiFQchHEYsL/T+OVvMro8UQ51+5ZX9q/3JMQq1f4qnXrlpomNaVzDcps/PsqRrPMUtoIcOiakYAugh08nZk+6XWGl7OF/74Q9mojtHpOqjK+XbyeKb51fObPqwzyRYr6PAzljkFfoXYN4A8QMWXDHDoMwnFj8qxU8DKN94KeDSCu dwff2IkK Qwb2kruXy2HU94B399NMT6K0Y8uRYckjGkMGpzBNBBpVJ4qmp1xhsnoOonOlpFuQTkSlbe3XCAzAv5IfkQU+pW3JV2CY5BFNEMlC9ciTOnV7liYKidyP+zsdwkDYEcJjzF+fBP3/V2w2FCg9jtLB+2max5pxu3r5vGKiJd1PymPbA249aydpQKJiBC7/8hPh6xm4B/FpdGlSmDqYtFA0qZ6Db+M2OdKF+HwfFaeNAkz9FfT3dm1F1KSAt3S0ORwgN2A7nQrvO1s3SQyAFs5gTslOG5p7HJvKKKcKCcyCYSkyL3A/36JUEW49KS7zIUPg75KHaVjYS+4/BtRqD7g74N6p4Zg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Implement `Allocator` for `Kmalloc`, the kernel's default allocator, typically used for objects smaller than page size. All memory allocations made with `Kmalloc` end up in `krealloc()`. It serves as allocator for the subsequently introduced types `KBox` and `KVec`. Signed-off-by: Danilo Krummrich --- rust/kernel/alloc.rs | 2 +- rust/kernel/alloc/allocator.rs | 89 +++++++++++++++++++++++++++++++++- 2 files changed, 89 insertions(+), 2 deletions(-) diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs index 6c21bd2edad9..535ed1527034 100644 --- a/rust/kernel/alloc.rs +++ b/rust/kernel/alloc.rs @@ -4,7 +4,7 @@ #[cfg(not(test))] #[cfg(not(testlib))] -mod allocator; +pub mod allocator; pub mod box_ext; pub mod vec_ext; diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index e32182f91167..7a93442187a1 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -1,12 +1,28 @@ // SPDX-License-Identifier: GPL-2.0 //! Allocator support. +//! +//! Documentation for the kernel's memory allocators can found in the "Memory Allocation Guide" +//! linked below. For instance, this includes the concept of "get free page" (GFP) flags and the +//! typical application of the different kernel allocators. +//! +//! Reference: use super::{flags::*, Flags}; use core::alloc::{GlobalAlloc, Layout}; use core::ptr; +use core::ptr::NonNull; -struct Kmalloc; +use crate::alloc::{AllocError, Allocator}; +use crate::bindings; + +/// The contiguous kernel allocator. +/// +/// `Kmalloc` is typically used for physically contiguous allocations up to page size, but also +/// supports larger allocations up to `bindings::KMALLOC_MAX_SIZE`, which is hardware specific. +/// +/// For more details see [self]. +pub struct Kmalloc; /// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment. fn aligned_size(new_layout: Layout) -> usize { @@ -36,6 +52,77 @@ pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: F unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 } } +/// # Invariants +/// +/// One of the following `krealloc`, `vrealloc`, `kvrealloc`. +struct ReallocFunc( + unsafe extern "C" fn(*const core::ffi::c_void, usize, u32) -> *mut core::ffi::c_void, +); + +impl ReallocFunc { + // INVARIANT: `krealloc` satisfies the type invariants. + const KREALLOC: Self = Self(bindings::krealloc); + + /// # Safety + /// + /// This method has the same safety requirements as [`Allocator::realloc`]. + /// + /// # Guarantees + /// + /// This method has the same guarantees as `Allocator::realloc`. Additionally + /// - it accepts any pointer to a valid memory allocation allocated by this function. + /// - memory allocated by this function remains valid until it is passed to this function. + unsafe fn call( + &self, + ptr: Option>, + layout: Layout, + flags: Flags, + ) -> Result, AllocError> { + let size = aligned_size(layout); + let ptr = match ptr { + Some(ptr) => ptr.as_ptr(), + None => ptr::null(), + }; + + // SAFETY: + // - `self.0` is one of `krealloc`, `vrealloc`, `kvrealloc` and thus only requires that + // `ptr` is NULL or valid. + // - `ptr` is either NULL or valid by the safety requirements of this function. + // + // GUARANTEE: + // - `self.0` is one of `krealloc`, `vrealloc`, `kvrealloc`. + // - Those functions provide the guarantees of this function. + let raw_ptr = unsafe { + // If `size == 0` and `ptr != NULL` the memory behind the pointer is freed. + self.0(ptr.cast(), size, flags.0).cast() + }; + + let ptr = if size == 0 { + NonNull::dangling() + } else { + NonNull::new(raw_ptr).ok_or(AllocError)? + }; + + Ok(NonNull::slice_from_raw_parts(ptr, size)) + } +} + +// SAFETY: `realloc` delegates to `ReallocFunc::call`, which guarantees that +// - memory remains valid until it is explicitly freed, +// - passing a pointer to a valid memory allocation is OK, +// - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same. +unsafe impl Allocator for Kmalloc { + #[inline] + unsafe fn realloc( + ptr: Option>, + layout: Layout, + flags: Flags, + ) -> Result, AllocError> { + // SAFETY: `ReallocFunc::call` has the same safety requirements as `Allocator::realloc`. + unsafe { ReallocFunc::KREALLOC.call(ptr, layout, flags) } + } +} + unsafe impl GlobalAlloc for Kmalloc { unsafe fn alloc(&self, layout: Layout) -> *mut u8 { // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety