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 6BC1B14012; Mon, 24 Feb 2025 14:55:43 +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=1740408943; cv=none; b=N9NcNsYK/Rh5bPfo1i9zYtDexW0SY+9QTAZGm4XNyPg7U4VnX4rnYzArVbUYsJrL4dNtP/m8tt1+2dFLUhWLYmArQb6MBxpaGdc+O+ydqUR2jIEUX5PegO8ne0HsebiOkoUPnxcnLrJv77fZEW8R34HQmCJjWoKKWUTSoCd5DZc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740408943; c=relaxed/simple; bh=jB+lyP+zuTp793Xk6AnrqmPDvaHvB42wqaXNkxAsRJw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rjnSLlti3IJp9DQ9SSfvMiUsCsbm8KBJEC00q54jCvmcVBsSsk7r/WsKAeRKjz6eWqxzQ0bOfAkU06RkEAd266ua3v8r7H+FXLjZvnC6ZtnIWQ1541voUy14JOR9n3reuNJEYg+a7SQPwUL0qs4MCdbjd27J2N6wP1yzKZZk1Hs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KikRnHuh; 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="KikRnHuh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE8ECC4CEE6; Mon, 24 Feb 2025 14:55:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1740408943; bh=jB+lyP+zuTp793Xk6AnrqmPDvaHvB42wqaXNkxAsRJw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KikRnHuhswkJPPD4uMqA+szw6ams7DjLpW/yATyG7IdDp3uyIuq/ZGYS120H7QvnM 0y+rsdfE2Ox/otFyjYJRTm14OkmJ+UiUkvjspzyncb7zAtgeQysMKTai0MGZ+nrNZv 0CnHBFr+MuVtdcf8lt3zFMzR4cofzQfN1l9YxZQs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gary Guo , Alice Ryhl , Miguel Ojeda Subject: [PATCH 6.13 050/138] rust: map `long` to `isize` and `char` to `u8` Date: Mon, 24 Feb 2025 15:34:40 +0100 Message-ID: <20250224142606.445501756@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250224142604.442289573@linuxfoundation.org> References: <20250224142604.442289573@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 6.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gary Guo commit 1bae8729e50a900f41e9a1c17ae81113e4cf62b8 upstream. The following FFI types are replaced compared to `core::ffi`: 1. `char` type is now always mapped to `u8`, since kernel uses `-funsigned-char` on the C code. `core::ffi` maps it to platform default ABI, which can be either signed or unsigned. 2. `long` is now always mapped to `isize`. It's very common in the kernel to use `long` to represent a pointer-sized integer, and in fact `intptr_t` is a typedef of `long` in the kernel. Enforce this mapping rather than mapping to `i32/i64` depending on platform can save us a lot of unnecessary casts. Signed-off-by: Gary Guo Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20240913213041.395655-5-gary@garyguo.net [ Moved `uaccess` changes from the next commit, since they were irrefutable patterns that Rust >= 1.82.0 warns about. Reworded slightly and reformatted a few documentation comments. Rebased on top of `rust-next`. Added the removal of two casts to avoid Clippy warnings. - Miguel ] Signed-off-by: Miguel Ojeda Signed-off-by: Greg Kroah-Hartman --- rust/ffi.rs | 37 ++++++++++++++++++++++++++++++++++++- rust/kernel/error.rs | 5 +---- rust/kernel/firmware.rs | 2 +- rust/kernel/miscdevice.rs | 4 ++-- rust/kernel/uaccess.rs | 27 +++++++-------------------- 5 files changed, 47 insertions(+), 28 deletions(-) --- a/rust/ffi.rs +++ b/rust/ffi.rs @@ -10,4 +10,39 @@ #![no_std] -pub use core::ffi::*; +macro_rules! alias { + ($($name:ident = $ty:ty;)*) => {$( + #[allow(non_camel_case_types, missing_docs)] + pub type $name = $ty; + + // Check size compatibility with `core`. + const _: () = assert!( + core::mem::size_of::<$name>() == core::mem::size_of::() + ); + )*} +} + +alias! { + // `core::ffi::c_char` is either `i8` or `u8` depending on architecture. In the kernel, we use + // `-funsigned-char` so it's always mapped to `u8`. + c_char = u8; + + c_schar = i8; + c_uchar = u8; + + c_short = i16; + c_ushort = u16; + + c_int = i32; + c_uint = u32; + + // In the kernel, `intptr_t` is defined to be `long` in all platforms, so we can map the type to + // `isize`. + c_long = isize; + c_ulong = usize; + + c_longlong = i64; + c_ulonglong = u64; +} + +pub use core::ffi::c_void; --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -153,11 +153,8 @@ impl Error { /// Returns the error encoded as a pointer. pub fn to_ptr(self) -> *mut T { - #[cfg_attr(target_pointer_width = "32", allow(clippy::useless_conversion))] // SAFETY: `self.0` is a valid error due to its invariant. - unsafe { - bindings::ERR_PTR(self.0.get().into()) as *mut _ - } + unsafe { bindings::ERR_PTR(self.0.get() as _) as *mut _ } } /// Returns a string representing the error, if one exists. --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -12,7 +12,7 @@ use core::ptr::NonNull; /// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`, /// `bindings::firmware_request_platform`, `bindings::request_firmware_direct`. struct FwFunc( - unsafe extern "C" fn(*mut *const bindings::firmware, *const i8, *mut bindings::device) -> i32, + unsafe extern "C" fn(*mut *const bindings::firmware, *const u8, *mut bindings::device) -> i32, ); impl FwFunc { --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -225,7 +225,7 @@ unsafe extern "C" fn fops_ioctl::borrow(private) }; - match T::ioctl(device, cmd, arg as usize) { + match T::ioctl(device, cmd, arg) { Ok(ret) => ret as c_long, Err(err) => err.to_errno() as c_long, } @@ -245,7 +245,7 @@ unsafe extern "C" fn fops_compat_ioctl::borrow(private) }; - match T::compat_ioctl(device, cmd, arg as usize) { + match T::compat_ioctl(device, cmd, arg) { Ok(ret) => ret as c_long, Err(err) => err.to_errno() as c_long, } --- a/rust/kernel/uaccess.rs +++ b/rust/kernel/uaccess.rs @@ -8,7 +8,7 @@ use crate::{ alloc::Flags, bindings, error::Result, - ffi::{c_ulong, c_void}, + ffi::c_void, prelude::*, transmute::{AsBytes, FromBytes}, }; @@ -224,13 +224,9 @@ impl UserSliceReader { if len > self.length { return Err(EFAULT); } - let Ok(len_ulong) = c_ulong::try_from(len) else { - return Err(EFAULT); - }; - // SAFETY: `out_ptr` points into a mutable slice of length `len_ulong`, so we may write + // SAFETY: `out_ptr` points into a mutable slice of length `len`, so we may write // that many bytes to it. - let res = - unsafe { bindings::copy_from_user(out_ptr, self.ptr as *const c_void, len_ulong) }; + let res = unsafe { bindings::copy_from_user(out_ptr, self.ptr as *const c_void, len) }; if res != 0 { return Err(EFAULT); } @@ -259,9 +255,6 @@ impl UserSliceReader { if len > self.length { return Err(EFAULT); } - let Ok(len_ulong) = c_ulong::try_from(len) else { - return Err(EFAULT); - }; let mut out: MaybeUninit = MaybeUninit::uninit(); // SAFETY: The local variable `out` is valid for writing `size_of::()` bytes. // @@ -272,7 +265,7 @@ impl UserSliceReader { bindings::_copy_from_user( out.as_mut_ptr().cast::(), self.ptr as *const c_void, - len_ulong, + len, ) }; if res != 0 { @@ -335,12 +328,9 @@ impl UserSliceWriter { if len > self.length { return Err(EFAULT); } - let Ok(len_ulong) = c_ulong::try_from(len) else { - return Err(EFAULT); - }; - // SAFETY: `data_ptr` points into an immutable slice of length `len_ulong`, so we may read + // SAFETY: `data_ptr` points into an immutable slice of length `len`, so we may read // that many bytes from it. - let res = unsafe { bindings::copy_to_user(self.ptr as *mut c_void, data_ptr, len_ulong) }; + let res = unsafe { bindings::copy_to_user(self.ptr as *mut c_void, data_ptr, len) }; if res != 0 { return Err(EFAULT); } @@ -359,9 +349,6 @@ impl UserSliceWriter { if len > self.length { return Err(EFAULT); } - let Ok(len_ulong) = c_ulong::try_from(len) else { - return Err(EFAULT); - }; // SAFETY: The reference points to a value of type `T`, so it is valid for reading // `size_of::()` bytes. // @@ -372,7 +359,7 @@ impl UserSliceWriter { bindings::_copy_to_user( self.ptr as *mut c_void, (value as *const T).cast::(), - len_ulong, + len, ) }; if res != 0 {