Experimental tracepoint support

rust/bindings/bindings_helper.h

@@ -15,6 +15,7 @@
 #include <linux/refcount.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
+#include <linux/tracepoint.h>
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 

rust/bindings/lib.rs

@@ -48,3 +48,18 @@ mod bindings_helper {
 }
 
 pub use bindings_raw::*;
+
+/// Rust version of the C macro `rcu_dereference_raw`.
+///
+/// The rust helper only works with void pointers, but this wrapper method makes it work with any
+/// pointer type using pointer casts.
+///
+/// # Safety
+///
+/// This method has the same safety requirements as the C macro of the same name.
+#[inline(always)]
+pub unsafe fn rcu_dereference_raw<T>(p: *const *mut T) -> *mut T {
+ // SAFETY: This helper calls into the C macro, so the caller promises to uphold the safety
+ // requirements.
+ unsafe { __rcu_dereference_raw(p as *mut *mut _) as *mut T }
+}

rust/helpers.c

@@ -165,6 +165,24 @@ rust_helper_krealloc(const void *objp, size_t new_size, gfp_t flags)
 }
 EXPORT_SYMBOL_GPL(rust_helper_krealloc);
 
+void rust_helper_preempt_enable_notrace(void)
+{
+ preempt_enable_notrace();
+}
+EXPORT_SYMBOL_GPL(rust_helper_preempt_enable_notrace);
+
+void rust_helper_preempt_disable_notrace(void)
+{
+ preempt_disable_notrace();
+}
+EXPORT_SYMBOL_GPL(rust_helper_preempt_disable_notrace);
+
+void *rust_helper___rcu_dereference_raw(void **p)
+{
+ return rcu_dereference_raw(p);
+}
+EXPORT_SYMBOL_GPL(rust_helper___rcu_dereference_raw);
+
 /*
  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
  * use it in contexts where Rust expects a `usize` like slice (array) indices.

rust/kernel/lib.rs

@@ -38,12 +38,15 @@ pub mod net;
 pub mod prelude;
 pub mod print;
 mod static_assert;
+pub mod static_call;
+pub mod static_key;
 #[doc(hidden)]
 pub mod std_vendor;
 pub mod str;
 pub mod sync;
 pub mod task;
 pub mod time;
+pub mod tracepoint;
 pub mod types;
 pub mod workqueue;
 

rust/kernel/static_call.rs

@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2024 Google LLC.
+
+//! Logic for static calls.
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! ty_underscore_for {
+ ($arg:expr) => {
+ _
+ };
+}
+
+#[doc(hidden)]
+#[repr(transparent)]
+pub struct AddressableStaticCallKey {
+ _ptr: *const bindings::static_call_key,
+}
+unsafe impl Sync for AddressableStaticCallKey {}
+impl AddressableStaticCallKey {
+ pub const fn new(ptr: *const bindings::static_call_key) -> Self {
+ Self { _ptr: ptr }
+ }
+}
+
+#[cfg(CONFIG_HAVE_STATIC_CALL)]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _static_call {
+ ($name:ident($($args:expr),* $(,)?)) => {{
+ // Symbol mangling will give this symbol a unique name.
+ #[cfg(CONFIG_HAVE_STATIC_CALL_INLINE)]
+ #[link_section = ".discard.addressable"]
+ #[used]
+ static __ADDRESSABLE: $crate::static_call::AddressableStaticCallKey = unsafe {
+ $crate::static_call::AddressableStaticCallKey::new(::core::ptr::addr_of!(
+ $crate::macros::paste! { $crate::bindings:: [<__SCK__ $name >]; }
+ ))
+ };
+
+ let fn_ptr: unsafe extern "C" fn($($crate::static_call::ty_underscore_for!($args)),*) -> _ =
+ $crate::macros::paste! { $crate::bindings:: [<__SCT__ $name >]; };
+ (fn_ptr)($($args),*)
+ }};
+}
+
+#[cfg(not(CONFIG_HAVE_STATIC_CALL))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _static_call {
+ ($name:ident($($args:expr),* $(,)?)) => {{
+ let void_ptr_fn: *mut ::core::ffi::c_void = $crate::macros::paste! { $crate::bindings:: [<__SCK__ $name >]; }.func;
+
+ let fn_ptr: unsafe extern "C" fn($($crate::static_call::ty_underscore_for!($args)),*) -> _ = if true {
+ ::core::mem::transmute(void_ptr_fn)
+ } else {
+ // This is dead code, but it influences type inference on `fn_ptr` so that we transmute
+ // the function pointer to the right type.
+ $crate::macros::paste! { $crate::bindings:: [<__SCT__ $name >]; }
+ };
+
+ (fn_ptr)($($args),*)
+ }};
+}
+
+/// Statically call a global function.
+///
+/// # Safety
+///
+/// This macro will call the provided function. It is up to the caller to uphold the safety
+/// guarantees of the function.
+///
+/// # Examples
+///
+/// ```ignore
+/// fn call_static() {
+/// unsafe {
+/// static_call! { your_static_call() };
+/// }
+/// }
+/// ```
+#[macro_export]
+macro_rules! static_call {
+ // Forward to the real implementation. Separated like this so that we don't have to duplicate
+ // the documentation.
+ ($($args:tt)*) => { $crate::static_call::_static_call! { $($args)* } };
+}
+
+pub use {_static_call, static_call, ty_underscore_for};

rust/kernel/static_key.rs

@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2024 Google LLC.
+
+//! Logic for static keys.
+
+use crate::bindings::*;
+
+#[doc(hidden)]
+#[macro_export]
+#[cfg(target_arch = "x86_64")]
+#[cfg(not(CONFIG_HAVE_RUST_ASM_GOTO))]
+macro_rules! _static_key_false {
+ ($key:path, $keytyp:ty, $field:ident) => {{
+ let mut output = 1u32;
+
+ core::arch::asm!(
+ r#"
+ 1: .byte 0x0f,0x1f,0x44,0x00,0x00
+
+ .pushsection __jump_table, "aw"
+ .balign 8
+ .long 1b - .
+ .long 3f - .
+ .quad {0} + {1} - .
+ .popsection
+
+ 2: mov {2:e}, 0
+ 3:
+ "#,
+ sym $key,
+ const ::core::mem::offset_of!($keytyp, $field),
+ inout(reg) output,
+ );
+
+ output != 0
+ }};
+}
+
+#[doc(hidden)]
+#[macro_export]
+#[cfg(target_arch = "x86_64")]
+#[cfg(CONFIG_HAVE_RUST_ASM_GOTO)]
+macro_rules! _static_key_false {
+ ($key:path, $keytyp:ty, $field:ident) => {'my_label: {
+ core::arch::asm!(
+ r#"
+ 1: .byte 0x0f,0x1f,0x44,0x00,0x00
+
+ .pushsection __jump_table, "aw"
+ .balign 8
+ .long 1b - .
+ .long {0} - .
+ .quad {1} + {2} - .
+ .popsection
+ "#,
+ label {
+ break 'my_label true;
+ },
+ sym $key,
+ const ::core::mem::offset_of!($keytyp, $field),
+ );
+
+ break 'my_label false;
+ }};
+}
+
+#[doc(hidden)]
+#[macro_export]
+#[cfg(target_arch = "aarch64")]
+#[cfg(not(CONFIG_HAVE_RUST_ASM_GOTO))]
+macro_rules! _static_key_false {
+ ($key:path, $keytyp:ty, $field:ident) => {{
+ let mut output = 1u32;
+
+ core::arch::asm!(
+ r#"
+ 1: nop
+
+ .pushsection __jump_table, "aw"
+ .align 3
+ .long 1b - ., 3f - .
+ .quad {0} + {1} - .
+ .popsection
+
+ 2: mov {2:w}, 0
+ 3:
+ "#,
+ sym $key,
+ const ::core::mem::offset_of!($keytyp, $field),
+ inout(reg) output
+ );
+
+ output != 0
+ }};
+}
+
+#[doc(hidden)]
+#[macro_export]
+#[cfg(target_arch = "aarch64")]
+#[cfg(CONFIG_HAVE_RUST_ASM_GOTO)]
+macro_rules! _static_key_false {
+ ($key:path, $keytyp:ty, $field:ident) => {'my_label: {
+ core::arch::asm!(
+ r#"
+ 1: nop
+
+ .pushsection __jump_table, "aw"
+ .align 3
+ .long 1b - ., {0} - .
+ .quad {1} + {2} - .
+ .popsection
+ "#,
+ label {
+ break 'my_label true;
+ },
+ sym $key,
+ const ::core::mem::offset_of!($keytyp, $field),
+ );
+
+ break 'my_label false;
+ }};
+}
+
+/// Branch based on a static key.
+///
+/// Takes three arguments:
+///
+/// * `key` - the path to the static variable containing the `static_key`.
+/// * `keytyp` - the type of `key`.
+/// * `field` - the name of the field of `key` that contains the `static_key`.
+#[macro_export]
+macro_rules! static_key_false {
+ // Forward to the real implementation. Separated like this so that we don't have to duplicate
+ // the documentation.
+ ($key:path, $keytyp:ty, $field:ident) => {{
+ // Assert that `$key` has type `$keytyp` and that `$key.$field` has type `static_key`.
+ //
+ // SAFETY: We know that `$key` is a static because otherwise the inline assembly will not
+ // compile. The raw pointers created in this block are in-bounds of `$key`.
+ static _TY_ASSERT: () = unsafe {
+ let key: *const $keytyp = ::core::ptr::addr_of!($key);
+ let _: *const $crate::bindings::static_key = ::core::ptr::addr_of!((*key).$field);
+ };
+
+ $crate::static_key::_static_key_false! { $key, $keytyp, $field }
+ }};
+}
+
+pub use {_static_key_false, static_key_false};