1 files changed, 50 insertions, 5 deletions

diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index fa9ecc42602a..f33c13c3ff97 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -14,6 +14,7 @@ use crate::{
     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 @@ pub trait MiscDevice: Sized {
         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: <Self::Ptr as ForeignOwnable>::Borrowed<'_>,
+        _file: &File,
+        _vma: &VmaNew,
+    ) -> Result {
+        build_error!(VTABLE_DEFAULT_ERROR)
+    }
+
     /// Handler for ioctls.
     ///
     /// The `cmd` argument is usually manipulated using the utilties in [`kernel::ioctl`].
@@ -200,7 +217,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
         // type.
         //
         // SAFETY: The open call of a file can access the private data.
-        unsafe { (*raw_file).private_data = ptr.into_foreign() };
+        unsafe { (*raw_file).private_data = ptr.into_foreign().cast() };
 
         0
     }
@@ -211,7 +228,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
     /// must be associated with a `MiscDeviceRegistration<T>`.
     unsafe extern "C" fn release(_inode: *mut bindings::inode, file: *mut bindings::file) -> c_int {
         // SAFETY: The release call of a file owns the private data.
-        let private = unsafe { (*file).private_data };
+        let private = unsafe { (*file).private_data }.cast();
         // SAFETY: The release call of a file owns the private data.
         let ptr = unsafe { <T::Ptr as ForeignOwnable>::from_foreign(private) };
 
@@ -226,9 +243,36 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
     /// # Safety
     ///
     /// `file` must be a valid file that is associated with a `MiscDeviceRegistration<T>`.
+    /// `vma` must be a vma that is currently being mmap'ed with this file.
+    unsafe extern "C" fn 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 { <T::Ptr as ForeignOwnable>::borrow(private.cast()) };
+        // 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<T>`.
     unsafe extern "C" fn ioctl(file: *mut bindings::file, cmd: c_uint, arg: c_ulong) -> c_long {
         // SAFETY: The ioctl call of a file can access the private data.
-        let private = unsafe { (*file).private_data };
+        let private = unsafe { (*file).private_data }.cast();
         // SAFETY: Ioctl calls can borrow the private data of the file.
         let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
 
@@ -253,7 +297,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
         arg: c_ulong,
     ) -> c_long {
         // SAFETY: The compat ioctl call of a file can access the private data.
-        let private = unsafe { (*file).private_data };
+        let private = unsafe { (*file).private_data }.cast();
         // SAFETY: Ioctl calls can borrow the private data of the file.
         let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
 
@@ -274,7 +318,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
     /// - `seq_file` must be a valid `struct seq_file` that we can write to.
     unsafe extern "C" fn show_fdinfo(seq_file: *mut bindings::seq_file, file: *mut bindings::file) {
         // SAFETY: The release call of a file owns the private data.
-        let private = unsafe { (*file).private_data };
+        let private = unsafe { (*file).private_data }.cast();
         // SAFETY: Ioctl calls can borrow the private data of the file.
         let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
         // SAFETY:
@@ -291,6 +335,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
     const VTABLE: bindings::file_operations = bindings::file_operations {
         open: Some(Self::open),
         release: Some(Self::release),
+        mmap: if T::HAS_MMAP { Some(Self::mmap) } else { None },
         unlocked_ioctl: if T::HAS_IOCTL {
             Some(Self::ioctl)
         } else {