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b=isdAQEK+fyU9LQiPmikCYp+he+tsGnTfNWAcIIkeyh6V5XNcGEHFQYit/ZlRDcAa2 IOa1mMRJ6iOotZftnaTIpKf1+8I1A3Hg/20Da19AY13ysIGSwD2d6wdd9//ouP18cz y0vK4k+8CyjavjrnlM+d4IT9RtcikiE1zAT01ZjYBvp2LjtiMNLnYUBi+tMpu9okhH 5o0W0NG6ln3yvuNyu4svUcpGRnWXsdthSUKYBLl5LxTgriaBcAVdVYh1O90kT6E8zM 5+MyZjCtVE8HQAt0w4vXmUNmEaGCrcmgt79gmeSW+lbC0PhJyxa1jKO7Uuym76dtZO rkkHlrWKeoMAg== 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 v9 25/29] rust: alloc: implement `Cmalloc` in module allocator_test Date: Fri, 4 Oct 2024 17:41:29 +0200 Message-ID: <20241004154149.93856-26-dakr@kernel.org> X-Mailer: git-send-email 2.46.1 In-Reply-To: <20241004154149.93856-1-dakr@kernel.org> References: <20241004154149.93856-1-dakr@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 64ED28000E X-Stat-Signature: nfyg17f7nrn98fpru81b6syj655qhg6y X-HE-Tag: 1728056664-357243 X-HE-Meta: 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 yU7nlNdL 3E9kBffZxkLDfrt7S8IC7vGGOVSodrhIuz2j5wnw3PtiJwLZ6jIivyhi6NWkuMswl+WDL2Y1Qg1qNjyBCK0n3yfxDOAVG7KEb5D2d5j7++oK4KGo44OtsDcZltNV5x6Yh+XA5KLMDwP+jqxm3u67Y9uFsdzxmglvuTWpb0etw5YAuCqLDgiNSk6zFA5NMM+1S0O8JzPAcUHB8jxN+lML88MCAIljMkbMB4+ePKzIbbXzkTMobRiXx7vTEJPN5qqBzbi0U5FPHJjRZesF3JRj0zf8EJyy/pHhKwjmVYBTAWBSKXrjvfKVE9MjX0m1DXFlJ5+g6p1hPOIlIWgPpj+Ook4w53CBSYKxDBiyi5xc9rdGBXQv8Ay4bP3+TsBrogdCOIe0I+sjUgTVS1x/OWmQMfPtT0SE6AyCAPk51 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: 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 --- rust/kernel/alloc/allocator_test.rs | 88 ++++++++++++++++++++++++++--- 1 file changed, 81 insertions(+), 7 deletions(-) diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs index 1b2642c547ec..47c2b509898e 100644 --- a/rust/kernel/alloc/allocator_test.rs +++ b/rust/kernel/alloc/allocator_test.rs @@ -1,21 +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, - _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 preceeding 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())) } } -- 2.46.1