ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/rust/bindings/lib.rs b/rust/bindings/lib.rs
new file mode 100644
index 000000000..812f8e5a0
--- /dev/null
+++ b/rust/bindings/lib.rs
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Bindings.
+//!
+//! Imports the generated bindings by `bindgen`.
+//!
+//! This crate may not be directly used. If you need a kernel C API that is
+//! not ported or wrapped in the `kernel` crate, then do so first instead of
+//! using this crate.
+
+#![no_std]
+#![allow(
+    clippy::all,
+    missing_docs,
+    non_camel_case_types,
+    non_upper_case_globals,
+    non_snake_case,
+    improper_ctypes,
+    unreachable_pub,
+    unsafe_op_in_unsafe_fn
+)]
+#![feature(cfi_encoding)]
+
+#[allow(dead_code)]
+#[allow(clippy::cast_lossless)]
+#[allow(clippy::ptr_as_ptr)]
+#[allow(clippy::ref_as_ptr)]
+#[allow(clippy::undocumented_unsafe_blocks)]
+#[cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))]
+#[cfg_attr(
+    CONFIG_RUSTC_HAS_SUSPICIOUS_RUNTIME_SYMBOL_DEFINITIONS,
+    allow(suspicious_runtime_symbol_definitions)
+)]
+mod bindings_raw {
+    use pin_init::{MaybeZeroable, Zeroable};
+
+    // Manual definition for blocklisted types.
+    type __kernel_size_t = usize;
+    type __kernel_ssize_t = isize;
+    type __kernel_ptrdiff_t = isize;
+
+    // `bindgen` doesn't automatically do this, see
+    // <https://github.com/rust-lang/rust-bindgen/issues/3196>
+    //
+    // SAFETY: `__BindgenBitfieldUnit<Storage>` is a newtype around `Storage`.
+    unsafe impl<Storage> Zeroable for __BindgenBitfieldUnit<Storage> where Storage: Zeroable {}
+
+    // Use glob import here to expose all helpers.
+    // Symbols defined within the module will take precedence to the glob import.
+    pub use super::bindings_helper::*;
+    include!(concat!(
+        env!("OBJTREE"),
+        "/rust/bindings/bindings_generated.rs"
+    ));
+}
+
+// When both a directly exposed symbol and a helper exists for the same function,
+// the directly exposed symbol is preferred and the helper becomes dead code, so
+// ignore the warning here.
+#[allow(dead_code)]
+mod bindings_helper {
+    // Import the generated bindings for types.
+    use super::bindings_raw::*;
+    include!(concat!(
+        env!("OBJTREE"),
+        "/rust/bindings/bindings_helpers_generated.rs"
+    ));
+}
+
+pub use bindings_raw::*;
+
+pub const compat_ptr_ioctl: Option<
+    unsafe extern "C" fn(*mut file, ffi::c_uint, ffi::c_ulong) -> ffi::c_long,
+> = {
+    #[cfg(CONFIG_COMPAT)]
+    {
+        Some(bindings_raw::compat_ptr_ioctl)
+    }
+    #[cfg(not(CONFIG_COMPAT))]
+    {
+        None
+    }
+};