On Thu, Aug 22, 2024 at 12:08:07PM +0000, Alice Ryhl wrote: > Add just enough support for static key so that we can use it from > tracepoints. Tracepoints rely on `static_key_false` even though it is > deprecated, so we add the same functionality to Rust. > > This patch only provides a generic implementation without code patching > (matching the one used when CONFIG_JUMP_LABEL is disabled). Later > patches add support for inline asm implementations that use runtime > patching. > > When CONFIG_JUMP_LABEL is unset, `static_key_count` is a static inline > function, so a Rust helper is defined for `static_key_count` in this > case. If Rust is compiled with LTO, this call should get inlined. The > helper can be eliminated once we have the necessary inline asm to make > atomic operations from Rust. > > Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx> Regards, Boqun > --- > This is an alternate version of patch 1 that resolves the conflict with > https://lore.kernel.org/all/20240725183325.122827-7-ojeda@xxxxxxxxxx/ > > rust/bindings/bindings_helper.h | 1 + > rust/helpers/helpers.c | 1 + > rust/helpers/tracepoint.c | 18 ++++++++++++++++++ > rust/kernel/jump_label.rs | 29 +++++++++++++++++++++++++++++ > rust/kernel/lib.rs | 1 + > 5 files changed, 50 insertions(+) > create mode 100644 rust/helpers/tracepoint.c > create mode 100644 rust/kernel/jump_label.rs > > diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h > index ae82e9c941af..e0846e7e93e6 100644 > --- a/rust/bindings/bindings_helper.h > +++ b/rust/bindings/bindings_helper.h > @@ -14,6 +14,7 @@ > #include <linux/ethtool.h> > #include <linux/firmware.h> > #include <linux/jiffies.h> > +#include <linux/jump_label.h> > #include <linux/mdio.h> > #include <linux/phy.h> > #include <linux/refcount.h> > diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c > index 173533616c91..5b17839de43a 100644 > --- a/rust/helpers/helpers.c > +++ b/rust/helpers/helpers.c > @@ -20,6 +20,7 @@ > #include "slab.c" > #include "spinlock.c" > #include "task.c" > +#include "tracepoint.c" > #include "uaccess.c" > #include "wait.c" > #include "workqueue.c" > diff --git a/rust/helpers/tracepoint.c b/rust/helpers/tracepoint.c > new file mode 100644 > index 000000000000..02aafb2b226f > --- /dev/null > +++ b/rust/helpers/tracepoint.c > @@ -0,0 +1,18 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +/* > + * Helpers for tracepoints. At the moment, helpers are only needed when > + * CONFIG_JUMP_LABEL is disabled, as `static_key_count` is only marked inline > + * in that case. > + * > + * Copyright (C) 2024 Google LLC. > + */ > + > +#include <linux/jump_label.h> > + > +#ifndef CONFIG_JUMP_LABEL > +int rust_helper_static_key_count(struct static_key *key) > +{ > + return static_key_count(key); > +} > +#endif > diff --git a/rust/kernel/jump_label.rs b/rust/kernel/jump_label.rs > new file mode 100644 > index 000000000000..011e1fc1d19a > --- /dev/null > +++ b/rust/kernel/jump_label.rs > @@ -0,0 +1,29 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +// Copyright (C) 2024 Google LLC. > + > +//! Logic for static keys. > +//! > +//! C header: [`include/linux/jump_label.h`](srctree/include/linux/jump_label.h). > + > +/// 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`. > +/// > +/// # Safety > +/// > +/// The macro must be used with a real static key defined by C. > +#[macro_export] > +macro_rules! static_key_false { > + ($key:path, $keytyp:ty, $field:ident) => {{ > + let _key: *const $keytyp = ::core::ptr::addr_of!($key); > + let _key: *const $crate::bindings::static_key = ::core::ptr::addr_of!((*_key).$field); > + > + $crate::bindings::static_key_count(_key.cast_mut()) > 0 > + }}; > +} > +pub use static_key_false; > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs > index 274bdc1b0a82..91af9f75d121 100644 > --- a/rust/kernel/lib.rs > +++ b/rust/kernel/lib.rs > @@ -36,6 +36,7 @@ > pub mod firmware; > pub mod init; > pub mod ioctl; > +pub mod jump_label; > #[cfg(CONFIG_KUNIT)] > pub mod kunit; > #[cfg(CONFIG_NET)] > -- > 2.46.0.184.g6999bdac58-goog >
