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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 , Linus Torvalds , linux-kernel@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org, Alice Ryhl Content-Type: text/plain; charset="utf-8" X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: BD09F20008 X-Stat-Signature: syrj9km5ap6cfu5mt6w33k1upo5rbfse X-HE-Tag: 1741089114-197169 X-HE-Meta: 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 YNuVahiw huTYyMSaxMoQ4M+JvW38zdVBeN7YUWXaMmb5EO7jlDF1/kdTuIJzlu4cQvJk1o0hNuZgocD/kwUizYsAnXgJXprZgvpjGMHflrSCqkXQvjdpkNhOyqfwys1FffnP7lHm6j7Y3isyfn2kxYuIuWpCgjtoYazLaIQOl2t42BaXJHDiOQuSs0N3RtIBlkcgquMG3C9NWAGGmqwMIycGh7Vcv/Lxra9GMJF4TuG6T8BW4ckzyxim3enMGXvwVNeUBjGqv2/QIlLmyRf2O9uDThHEl7Oigich7BRarbt8N8z3M5xcxFAHOM8ZeJg4fN8/rh1K5n/b0omL8cFabShs4gLF5Vhq+xurgpwH16X2FA6/eTksxuOFukuW8bXMQbyNIYtJv+7yZlIPw2FRUXqqmFua+jeLuv7lPxGBCEm95K59Nw/mO5ACSGztPCZzajnAIBIl3tSCu5q2JPg+GeIPEkJz0PYWA8VuvpTJe/gENarbrrLmsvO9EAG0JqK0X3BekivnY31PAE1Q2dasHqeYBC98/sBJ5KDHd6QTd/E28xUmMlW+cfwpH/9H8IHqRqXfxVnGBLmm6BYRlgTPsh9BS9G1De3hWuvV78Ex3KzNcgeCogGVwBSBiWKg3+QBiftxo/JPiaRtJu5BlGakV7yJGQNQhyGZM5v9m1YPcHGkGY3Z/bnJlq1GoSDP5gSBeL1cgVl0gIIeVg7X6lPRcd3ipsfjSuUMM5wARWhvBpE0s0CTDpXBI6LFseY9ktTDqPkabw3Gv/FjRFxbx2A2CGmxAyYhUndy2n8nVWPipT20+IemuSek2Jjc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.209841, 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 Acked-by: Liam R. Howlett Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo 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 e14433b2ab9d8fa391474b2ad7e3ed55c64b4d91..e4a2c599683243ac955b7c95e0645b8c1010b25f 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`. -- 2.48.1.711.g2feabab25a-goog