[v3] rust: ioctl: Add ioctl number manipulation functions
Commit Message
Add simple 1:1 wrappers of the C ioctl number manipulation functions.
Since these are macros we cannot bindgen them directly, and since they
should be usable in const context we cannot use helper wrappers, so
we'll have to reimplement them in Rust. Thankfully, the C headers do
declare defines for the relevant bitfield positions, so we don't need
to duplicate that.
Signed-off-by: Asahi Lina <lina@asahilina.net>
---
Changes in v3:
- Actually made the change intended in v2.
- Link to v2: https://lore.kernel.org/r/20230224-rust-ioctl-v2-1-5325e76a92df@asahilina.net
Changes in v2:
- Changed from assert!() to build_assert!() (static_assert!() can't work
here)
- Link to v1: https://lore.kernel.org/r/20230224-rust-ioctl-v1-1-5142d365a934@asahilina.net
---
rust/bindings/bindings_helper.h | 3 +-
rust/kernel/ioctl.rs | 71 +++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
3 files changed, 74 insertions(+), 1 deletion(-)
---
base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
change-id: 20230224-rust-ioctl-a520f3eb3aa8
Thank you,
~~ Lina
Comments
On Thu, Mar 23, 2023 at 1:34 PM Asahi Lina <lina@asahilina.net> wrote:
>
> Changes in v3:
> - Actually made the change intended in v2.
> - Link to v2: https://lore.kernel.org/r/20230224-rust-ioctl-v2-1-5325e76a92df@asahilina.net
>
> Changes in v2:
> - Changed from assert!() to build_assert!() (static_assert!() can't work
> here)
> - Link to v1: https://lore.kernel.org/r/20230224-rust-ioctl-v1-1-5142d365a934@asahilina.net
It seems `#[inline(always)]` got added to a few of those, right? (The
addition looks fine to me, but just to understand if is it an omission
in the changelog, or an unintended change, or intended for another
reason).
Thanks!
Cheers,
Miguel
On 23/03/2023 22.05, Miguel Ojeda wrote:
> On Thu, Mar 23, 2023 at 1:34 PM Asahi Lina <lina@asahilina.net> wrote:
>>
>> Changes in v3:
>> - Actually made the change intended in v2.
>> - Link to v2: https://lore.kernel.org/r/20230224-rust-ioctl-v2-1-5325e76a92df@asahilina.net
>>
>> Changes in v2:
>> - Changed from assert!() to build_assert!() (static_assert!() can't work
>> here)
>> - Link to v1: https://lore.kernel.org/r/20230224-rust-ioctl-v1-1-5142d365a934@asahilina.net
>
> It seems `#[inline(always)]` got added to a few of those, right? (The
> addition looks fine to me, but just to understand if is it an omission
> in the changelog, or an unintended change, or intended for another
> reason).
Ah yes, I should've mentioned that! build_assert!() only works for stuff
that can be const-optimized at build time, which requires inlining.
Otherwise this change immediately causes build failures since generic
variants of the functions get compiled (and since they're public
functions, cannot be optimized out at link time).
>
> Thanks!
>
> Cheers,
> Miguel
>
~~ Lina
@@ -6,8 +6,9 @@
* Sorted alphabetically.
*/
-#include <linux/slab.h>
+#include <linux/ioctl.h>
#include <linux/refcount.h>
+#include <linux/slab.h>
/* `bindgen` gets confused at certain things. */
const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL;
new file mode 100644
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+#![allow(non_snake_case)]
+
+//! ioctl() number definitions
+//!
+//! C header: [`include/asm-generic/ioctl.h`](../../../../include/asm-generic/ioctl.h)
+
+use crate::build_assert;
+
+/// Build an ioctl number, analogous to the C macro of the same name.
+#[inline(always)]
+const fn _IOC(dir: u32, ty: u32, nr: u32, size: usize) -> u32 {
+ build_assert!(dir <= bindings::_IOC_DIRMASK);
+ build_assert!(ty <= bindings::_IOC_TYPEMASK);
+ build_assert!(nr <= bindings::_IOC_NRMASK);
+ build_assert!(size <= (bindings::_IOC_SIZEMASK as usize));
+
+ (dir << bindings::_IOC_DIRSHIFT)
+ | (ty << bindings::_IOC_TYPESHIFT)
+ | (nr << bindings::_IOC_NRSHIFT)
+ | ((size as u32) << bindings::_IOC_SIZESHIFT)
+}
+
+/// Build an ioctl number for an argumentless ioctl.
+#[inline(always)]
+pub const fn _IO(ty: u32, nr: u32) -> u32 {
+ _IOC(bindings::_IOC_NONE, ty, nr, 0)
+}
+
+/// Build an ioctl number for an read-only ioctl.
+#[inline(always)]
+pub const fn _IOR<T>(ty: u32, nr: u32) -> u32 {
+ _IOC(bindings::_IOC_READ, ty, nr, core::mem::size_of::<T>())
+}
+
+/// Build an ioctl number for an write-only ioctl.
+#[inline(always)]
+pub const fn _IOW<T>(ty: u32, nr: u32) -> u32 {
+ _IOC(bindings::_IOC_WRITE, ty, nr, core::mem::size_of::<T>())
+}
+
+/// Build an ioctl number for a read-write ioctl.
+#[inline(always)]
+pub const fn _IOWR<T>(ty: u32, nr: u32) -> u32 {
+ _IOC(
+ bindings::_IOC_READ | bindings::_IOC_WRITE,
+ ty,
+ nr,
+ core::mem::size_of::<T>(),
+ )
+}
+
+/// Get the ioctl direction from an ioctl number.
+pub const fn _IOC_DIR(nr: u32) -> u32 {
+ (nr >> bindings::_IOC_DIRSHIFT) & bindings::_IOC_DIRMASK
+}
+
+/// Get the ioctl type from an ioctl number.
+pub const fn _IOC_TYPE(nr: u32) -> u32 {
+ (nr >> bindings::_IOC_TYPESHIFT) & bindings::_IOC_TYPEMASK
+}
+
+/// Get the ioctl number from an ioctl number.
+pub const fn _IOC_NR(nr: u32) -> u32 {
+ (nr >> bindings::_IOC_NRSHIFT) & bindings::_IOC_NRMASK
+}
+
+/// Get the ioctl size from an ioctl number.
+pub const fn _IOC_SIZE(nr: u32) -> usize {
+ ((nr >> bindings::_IOC_SIZESHIFT) & bindings::_IOC_SIZEMASK) as usize
+}
@@ -30,6 +30,7 @@ compile_error!("Missing kernel configuration for conditional compilation");
mod allocator;
mod build_assert;
pub mod error;
+pub mod ioctl;
pub mod prelude;
pub mod print;
mod static_assert;