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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: rspam08 X-Rspamd-Queue-Id: 9229A1C001C X-Stat-Signature: 43zdw649exkdu395ukgqxmhi7pxrer6k X-HE-Tag: 1739444693-970550 X-HE-Meta: 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 nvvjtgdh 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.401911, 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 `VmaNew` 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 Reviewed-by: Gary Guo --- rust/kernel/miscdevice.rs | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index e14433b2ab9d..e4a2c5996832 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::VmaNew, 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: &VmaNew, + ) -> 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 { VmaNew::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`.