[PATCH 7.3.y] rust: irq: declare cfi_encoding for irqreturn

[Sasha Levin <sashal@kernel.org>]

From: Sami Tolvanen <samitolvanen@google.com>

[ Upstream commit 01f3e6b4b1c8c1748e59ba53631ab1f5d9ad0ea4 ]

The IRQ callbacks return c_uint. C calls them through irq_handler_t,
which returns enum irqreturn. kCFI encodes enum types by name even with
integer normalization, so the type ids never match and every call fails
the CFI check.

Generate irqreturn as a newtype with a cfi_encoding, as is done for
lru_status, and return bindings::irqreturn_t from the callbacks.

Fixes: 0851d34a8cc3 ("rust: irq: add support for non-threaded IRQs and handlers")
Fixes: 135d40523244 ("rust: irq: add support for threaded IRQs and handlers")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261019-rust-cfi-fixes-v1-1-9503472ba738@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
[ sashal: Adjusted insertion context to preserve existing fwctl_rpc_scope CFI declarations. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 rust/bindgen_parameters    |  2 ++
 rust/kernel/irq/request.rs | 28 +++++++++++++++++-----------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/rust/bindgen_parameters b/rust/bindgen_parameters
index 39aae62dca669..cbc0a302647e5 100644
--- a/rust/bindgen_parameters
+++ b/rust/bindgen_parameters
@@ -29,6 +29,8 @@
 # enums that appear in indirect function calls should specify a cfi type
 --newtype-enum fwctl_rpc_scope
 --with-attribute-custom-enum=fwctl_rpc_scope='#[cfi_encoding="15fwctl_rpc_scope"]'
+--newtype-enum irqreturn
+--with-attribute-custom-enum=irqreturn='#[cfi_encoding="9irqreturn"]'
 --newtype-enum lru_status
 --with-attribute-custom-enum=lru_status='#[cfi_encoding="10lru_status"]'
 
diff --git a/rust/kernel/irq/request.rs b/rust/kernel/irq/request.rs
index c1c6525a676a7..1afa9fcaad1f6 100644
--- a/rust/kernel/irq/request.rs
+++ b/rust/kernel/irq/request.rs
@@ -25,10 +25,10 @@
 #[repr(u32)]
 pub enum IrqReturn {
     /// The interrupt was not from this device or was not handled.
-    None = bindings::irqreturn_IRQ_NONE,
+    None = bindings::irqreturn::IRQ_NONE.0,
 
     /// The interrupt was handled by this device.
-    Handled = bindings::irqreturn_IRQ_HANDLED,
+    Handled = bindings::irqreturn::IRQ_HANDLED.0,
 }
 
 /// Callbacks for an IRQ handler.
@@ -240,25 +240,28 @@ fn drop(self: Pin<&mut Self>) {
 /// # Safety
 ///
 /// This function should be only used as the callback in `request_irq`.
-unsafe extern "C" fn handle_irq_callback<T: Handler>(_irq: i32, ptr: *mut c_void) -> c_uint {
+unsafe extern "C" fn handle_irq_callback<T: Handler>(
+    _irq: i32,
+    ptr: *mut c_void,
+) -> bindings::irqreturn_t {
     let ptr = ptr.cast_const().cast::<Registration<'_, T>>();
     // SAFETY: `ptr` is a pointer to `Registration<'_, T>` set in `Registration::new()`.
     let registration = unsafe { &*ptr };
 
-    T::handle(&registration.handler) as c_uint
+    bindings::irqreturn_t(T::handle(&registration.handler) as c_uint)
 }
 
 /// The value that can be returned from [`ThreadedHandler::handle`].
 #[repr(u32)]
 pub enum ThreadedIrqReturn {
     /// The interrupt was not from this device or was not handled.
-    None = bindings::irqreturn_IRQ_NONE,
+    None = bindings::irqreturn::IRQ_NONE.0,
 
     /// The interrupt was handled by this device.
-    Handled = bindings::irqreturn_IRQ_HANDLED,
+    Handled = bindings::irqreturn::IRQ_HANDLED.0,
 
     /// The handler wants the handler thread to wake up.
-    WakeThread = bindings::irqreturn_IRQ_WAKE_THREAD,
+    WakeThread = bindings::irqreturn::IRQ_WAKE_THREAD.0,
 }
 
 /// Callbacks for a threaded IRQ handler.
@@ -461,23 +464,26 @@ fn drop(self: Pin<&mut Self>) {
 unsafe extern "C" fn handle_threaded_irq_callback<T: ThreadedHandler>(
     _irq: i32,
     ptr: *mut c_void,
-) -> c_uint {
+) -> bindings::irqreturn_t {
     let ptr = ptr.cast_const().cast::<ThreadedRegistration<'_, T>>();
     // SAFETY: `ptr` is a pointer to `ThreadedRegistration<'_, T>` set in
     // `ThreadedRegistration::new()`.
     let registration = unsafe { &*ptr };
 
-    T::handle(&registration.handler) as c_uint
+    bindings::irqreturn_t(T::handle(&registration.handler) as c_uint)
 }
 
 /// # Safety
 ///
 /// This function should be only used as the callback in `request_threaded_irq`.
-unsafe extern "C" fn thread_fn_callback<T: ThreadedHandler>(_irq: i32, ptr: *mut c_void) -> c_uint {
+unsafe extern "C" fn thread_fn_callback<T: ThreadedHandler>(
+    _irq: i32,
+    ptr: *mut c_void,
+) -> bindings::irqreturn_t {
     let ptr = ptr.cast_const().cast::<ThreadedRegistration<'_, T>>();
     // SAFETY: `ptr` is a pointer to `ThreadedRegistration<'_, T>` set in
     // `ThreadedRegistration::new()`.
     let registration = unsafe { &*ptr };
 
-    T::handle_threaded(&registration.handler) as c_uint
+    bindings::irqreturn_t(T::handle_threaded(&registration.handler) as c_uint)
 }
-- 
2.53.0