From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BDD3E22D799; Mon, 10 Mar 2025 17:20:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741627219; cv=none; b=ekF49CFbiouvtgBPIyLSzx365f+cRUh9dRQ/zKe9Lb7eE/t4IUu2hOr56j6lHXsl+Ey+zeFmh0DiA6CjK+JfmKHSiyzbM9bf8Myb/PjP/dNZPhZmVosHRTNT3lXCUU9ZvF9VRjP2c3f8TwWJsQJXBsUhkxvbiKtSmiwiwo4kFug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741627219; c=relaxed/simple; bh=Az+FMyBW7t3jKDAdsXA1zkCjUAOaonFd2qyLRo//7Ec=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Itu35Bdtdtgoa6M1ukbF5RuT7CBdf/ApV2QideojHuue6Ln876z7rX8kBZ5sxSw55jK7VQhBJu5WRykf9HNniNXZgAO6meqDP4sOOYu0prR7ZC3IGZzxQHlauTDs9ADx2YlOueEvGHkk7erbPFd5RuR4UyJtss1hvfkEf0yWEHY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Yxk57lcE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Yxk57lcE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 41EEAC4CEED; Mon, 10 Mar 2025 17:20:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741627219; bh=Az+FMyBW7t3jKDAdsXA1zkCjUAOaonFd2qyLRo//7Ec=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Yxk57lcEhhO6J8YuWEE2j+4rS94sdWz66raKjXgnbZ7jVJ0CIcex5+/0dOftXCd4y I8oZE9bFH2wQvZrZRM4mcWGjWRfJDuYtp1VdX7k9rwAVkIdzKnONilEdUKEDGY/a+h qrN+R3nvMqEAG9zAgyzzvU/ZCMrKlIZNiGeumj6Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Benno Lossin , Gary Guo , Danilo Krummrich , Miguel Ojeda Subject: [PATCH 6.12 055/269] rust: alloc: implement `Cmalloc` in module allocator_test Date: Mon, 10 Mar 2025 18:03:28 +0100 Message-ID: <20250310170459.920061927@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250310170457.700086763@linuxfoundation.org> References: <20250310170457.700086763@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Danilo Krummrich commit dd09538fb4093176a818fcecd45114430cc5840f upstream. So far the kernel's `Box` and `Vec` types can't be used by userspace test cases, since all users of those types (e.g. `CString`) use kernel allocators for instantiation. In order to allow userspace test cases to make use of such types as well, implement the `Cmalloc` allocator within the allocator_test module and type alias all kernel allocators to `Cmalloc`. The `Cmalloc` allocator uses libc's `realloc()` function as allocator backend. Reviewed-by: Benno Lossin Reviewed-by: Gary Guo Signed-off-by: Danilo Krummrich Link: https://lore.kernel.org/r/20241004154149.93856-26-dakr@kernel.org [ Removed the temporary `allow(dead_code)` as discussed in the list and fixed typo, added backticks. - Miguel ] Signed-off-by: Miguel Ojeda Signed-off-by: Greg Kroah-Hartman --- rust/kernel/alloc.rs | 1 rust/kernel/alloc/allocator_test.rs | 89 ++++++++++++++++++++++++++++++++---- 2 files changed, 81 insertions(+), 9 deletions(-) --- a/rust/kernel/alloc.rs +++ b/rust/kernel/alloc.rs @@ -215,7 +215,6 @@ pub unsafe trait Allocator { } } -#[allow(dead_code)] /// Returns a properly aligned dangling pointer from the given `layout`. pub(crate) fn dangling_from_layout(layout: Layout) -> NonNull { let ptr = layout.align() as *mut u8; --- a/rust/kernel/alloc/allocator_test.rs +++ b/rust/kernel/alloc/allocator_test.rs @@ -1,22 +1,95 @@ // SPDX-License-Identifier: GPL-2.0 +//! So far the kernel's `Box` and `Vec` types can't be used by userspace test cases, since all users +//! of those types (e.g. `CString`) use kernel allocators for instantiation. +//! +//! In order to allow userspace test cases to make use of such types as well, implement the +//! `Cmalloc` allocator within the allocator_test module and type alias all kernel allocators to +//! `Cmalloc`. The `Cmalloc` allocator uses libc's `realloc()` function as allocator backend. + #![allow(missing_docs)] -use super::{AllocError, Allocator, Flags}; +use super::{flags::*, AllocError, Allocator, Flags}; use core::alloc::Layout; +use core::cmp; +use core::ptr; use core::ptr::NonNull; -pub struct Kmalloc; +/// The userspace allocator based on libc. +pub struct Cmalloc; + +pub type Kmalloc = Cmalloc; pub type Vmalloc = Kmalloc; pub type KVmalloc = Kmalloc; -unsafe impl Allocator for Kmalloc { +extern "C" { + #[link_name = "aligned_alloc"] + fn libc_aligned_alloc(align: usize, size: usize) -> *mut core::ffi::c_void; + + #[link_name = "free"] + fn libc_free(ptr: *mut core::ffi::c_void); +} + +// SAFETY: +// - memory remains valid until it is explicitly freed, +// - passing a pointer to a valid memory allocation created by this `Allocator` is always OK, +// - `realloc` provides the guarantees as provided in the `# Guarantees` section. +unsafe impl Allocator for Cmalloc { unsafe fn realloc( - _ptr: Option>, - _layout: Layout, - _old_layout: Layout, - _flags: Flags, + ptr: Option>, + layout: Layout, + old_layout: Layout, + flags: Flags, ) -> Result, AllocError> { - panic!(); + let src = match ptr { + Some(src) => { + if old_layout.size() == 0 { + ptr::null_mut() + } else { + src.as_ptr() + } + } + None => ptr::null_mut(), + }; + + if layout.size() == 0 { + // SAFETY: `src` is either NULL or was previously allocated with this `Allocator` + unsafe { libc_free(src.cast()) }; + + return Ok(NonNull::slice_from_raw_parts( + crate::alloc::dangling_from_layout(layout), + 0, + )); + } + + // SAFETY: Returns either NULL or a pointer to a memory allocation that satisfies or + // exceeds the given size and alignment requirements. + let dst = unsafe { libc_aligned_alloc(layout.align(), layout.size()) } as *mut u8; + let dst = NonNull::new(dst).ok_or(AllocError)?; + + if flags.contains(__GFP_ZERO) { + // SAFETY: The preceding calls to `libc_aligned_alloc` and `NonNull::new` + // guarantee that `dst` points to memory of at least `layout.size()` bytes. + unsafe { dst.as_ptr().write_bytes(0, layout.size()) }; + } + + if !src.is_null() { + // SAFETY: + // - `src` has previously been allocated with this `Allocator`; `dst` has just been + // newly allocated, hence the memory regions do not overlap. + // - both` src` and `dst` are properly aligned and valid for reads and writes + unsafe { + ptr::copy_nonoverlapping( + src, + dst.as_ptr(), + cmp::min(layout.size(), old_layout.size()), + ) + }; + } + + // SAFETY: `src` is either NULL or was previously allocated with this `Allocator` + unsafe { libc_free(src.cast()) }; + + Ok(NonNull::slice_from_raw_parts(dst, layout.size())) } }