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Howlett" , Andrew Morton , Greg Kroah-Hartman , Arnd Bergmann , Jann Horn , Suren Baghdasaryan Cc: Alex Gaynor , Boqun Feng , Gary Guo , " =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= " , Benno Lossin , Andreas Hindborg , Trevor Gross , linux-kernel@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org, Alice Ryhl X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: CD59620006 X-Stat-Signature: bc8uwbp4b9q8ko8kcybzhj6xajkpxejj X-HE-Tag: 1738584928-555453 X-HE-Meta: U2FsdGVkX1/LY85pH8kt90ZfmCB+XwCG1gal6DWC7EHdvk7CZ20RK13KSuRIsFtbHZTihHoORZtw/uaWwig4vFj4YESuAoZzC3KSEgoxnKcxsJ9jS0leY7lloA79rYWUgQPrGtyagSddX3i9V1WkiFE98tkv3i6ZcMqLuaoWw4yDXjLAQ8eBDUUKKFYUC1GhWn5lvqQZmtwEtdg7K12WeCARqhW2nEFgK1ZzPjEntI/JB3wzxLfkSNWLPiATADbx02NpYrzLAsS4IiynsvrtAfCecAJU1vhszvNkRu2uOTevs8//yTr4iH1QpHkHpQhHdDHTusTPgBSF8btg3kdEp2hsmoNIp95xQTrRgzYAdyDsZPeJEJsG5y5MtOiiDiDkjPIc9hF9gJhO8Ma+8trxjORNXRmQYsUXRyTlN1bXNiy/qvwcdWyQ08u2x7cl3OJUtZUXiLcsJbVAarW6XICdPNyuMJvLL0CQi7T0DSv6t+zeNe1f7I0c1avldBu0eO702vZWCzqn8zZac1TGom9B7Oi0vOUV+SH5KtgAHcq5eWPH+gxz/d6yCOOOLrY1WO428ew77ul/JIQaaVRX3kTvN/kw7uUdlkd20skyaoJ1pTY/6Q/UgKX0KF8GjJ2k7UzvryBCQVMf4oCMQ2QG9b+EYfitx6GTODUae9V4KezYwjEPU7XivK+M/ioKi7TYsVCBjfOoLIlJsRI6dN7V+sRDZPZmhY1zmhD1v4+OscI6vaIj3/B+rMnJan5wY1SBaOWSd3/Q53JX8GraXzVJp5HZapJZJTqVNtcwC59Rbg0b1tnoyar6VyoPF5+0Wc09HTT8oihKNn9lIhXJNOjyXet3tJRu6gNRXu8tZt+PO0eduBmayZOx6ub3/p9C1RmdH9PKPJAwxBxX2L/wWpGpEaNfSD0h7eoy+IwQQnV92Ni6p1HV/WI13pAlyJUP0nvOQv8JoF9OnNfEhHz53m//N3L em02Y7Iy 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.386983, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add the ability to write a file_operations->mmap hook in Rust when using the miscdevice abstraction. The `vma` argument to the `mmap` hook uses the `VmAreaNew` type from the previous commit; this type provides the correct set of operations for a file_operations->mmap hook. Acked-by: Greg Kroah-Hartman Acked-by: Lorenzo Stoakes Reviewed-by: Andreas Hindborg Signed-off-by: Alice Ryhl --- rust/kernel/miscdevice.rs | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index e14433b2ab9d..97b2384f0816 100644 --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -14,6 +14,7 @@ error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR}, ffi::{c_int, c_long, c_uint, c_ulong}, fs::File, + mm::virt::VmAreaNew, prelude::*, seq_file::SeqFile, str::CStr, @@ -119,6 +120,22 @@ fn release(device: Self::Ptr, _file: &File) { drop(device); } + /// Handle for mmap. + /// + /// This function is invoked when a user space process invokes the `mmap` system call on + /// `file`. The function is a callback that is part of the VMA initializer. The kernel will do + /// initial setup of the VMA before calling this function. The function can then interact with + /// the VMA initialization by calling methods of `vma`. If the function does not return an + /// error, the kernel will complete initialization of the VMA according to the properties of + /// `vma`. + fn mmap( + _device: ::Borrowed<'_>, + _file: &File, + _vma: &VmAreaNew, + ) -> Result { + kernel::build_error!(VTABLE_DEFAULT_ERROR) + } + /// Handler for ioctls. /// /// The `cmd` argument is usually manipulated using the utilties in [`kernel::ioctl`]. @@ -176,6 +193,7 @@ impl VtableHelper { const VTABLE: bindings::file_operations = bindings::file_operations { open: Some(fops_open::), release: Some(fops_release::), + mmap: maybe_fn(T::HAS_MMAP, fops_mmap::), unlocked_ioctl: maybe_fn(T::HAS_IOCTL, fops_ioctl::), #[cfg(CONFIG_COMPAT)] compat_ioctl: if T::HAS_COMPAT_IOCTL { @@ -257,6 +275,32 @@ impl VtableHelper { 0 } +/// # Safety +/// +/// `file` must be a valid file that is associated with a `MiscDeviceRegistration`. +/// `vma` must be a vma that is currently being mmap'ed with this file. +unsafe extern "C" fn fops_mmap( + file: *mut bindings::file, + vma: *mut bindings::vm_area_struct, +) -> c_int { + // SAFETY: The mmap call of a file can access the private data. + let private = unsafe { (*file).private_data }; + // SAFETY: This is a Rust Miscdevice, so we call `into_foreign` in `open` and `from_foreign` in + // `release`, and `fops_mmap` is guaranteed to be called between those two operations. + let device = unsafe { ::borrow(private) }; + // SAFETY: The caller provides a vma that is undergoing initial VMA setup. + let area = unsafe { VmAreaNew::from_raw(vma) }; + // SAFETY: + // * The file is valid for the duration of this call. + // * There is no active fdget_pos region on the file on this thread. + let file = unsafe { File::from_raw_file(file) }; + + match T::mmap(device, file, area) { + Ok(()) => 0, + Err(err) => err.to_errno(), + } +} + /// # Safety /// /// `file` must be a valid file that is associated with a `MiscDeviceRegistration`.