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a=openpgp-sha256; l=3944; i=aliceryhl@google.com; h=from:subject:message-id; bh=XID7x+7coWgnGBd5wIl/yqAS/1AzuHdHb0QK8txVMPI=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBnIlkhPSPbRePqgmcZkeV4PnRFaF06ORWPyb4Hd ZssKOLJjQqJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZyJZIQAKCRAEWL7uWMY5 RqSUD/9jfyehgB5qzKfR0aAlCXJYAKb9ZzLWaNn1EmqHjp8saPikwqUESI5omMnEt6W8h+4ok42 pV4kX4p2S2qQqcKff9S5dttdXhdH2JZOmIXfwdu5yXJPN7oj5BpzCol3VvJux1Nx3JaScViKnG4 4e0udKPwtlAyubQDD/+0Uk/9ayGweHYNvknT+8hoyjxsNDfCl5mTdR5pa3yXcSQMfXN4Ck+MOQh VD91Vo5mSBpn2DItkLSUPSKgIP9aK7q4yXIaKLf9WgPwcsdzNxuJ/Ak1+IWPdqzEjp0hiq67KkE hmiSAknb+A1aOfNv9gGpdRM+AuuoXsLOnhD5/yv+0utf5lP32ktyNBPq4IoJMANrT0kqkJ+nAIu gs5Eut6gmmuj9FgL+wjElrMboABY6QE/SENYeDZe4xLaDnxQKSqfvem36mOcMTP7j/02/GHoSYB RyLsXv/rPzX0s467Y++J+vePxJuIrQFgS8PVcnA/8dnKfeoU+kE4buLiFk6G/HoS4dxGyqiYbF3 HMltLodkWAYZfs+nfTY3uUa5C7nDIZ+/QXJMyQ2VmpXgulpY7tPclpC1MxbFNAiPxW9jO1qVqOS GF2ERKm5fU5AwBn6KmQYgLsii6hIO/c+lfx1ndbl1K1zCZ0cC906aD5HA9HZrjMJ1EsMzzSVauC RVr59LvwW7YPQNA== X-Mailer: b4 0.13.0 Message-ID: <20241030-tracepoint-v12-1-eec7f0f8ad22@google.com> Subject: [PATCH v12 1/5] rust: add static_branch_unlikely for static_key_false From: Alice Ryhl To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Josh Poimboeuf , Jason Baron , Ard Biesheuvel , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg Cc: linux-trace-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann , linux-arch@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Mark Rutland , Ryan Roberts , Fuad Tabba , linux-arm-kernel@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , linux-riscv@lists.infradead.org, Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Andrew Morton , Tianrui Zhao , loongarch@lists.linux.dev, Alice Ryhl Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Add just enough support for static key so that we can use it from tracepoints. Tracepoints rely on `static_branch_unlikely` with a `struct static_key_false`, 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. Reviewed-by: Boqun Feng Reviewed-by: Gary Guo Signed-off-by: Alice Ryhl --- rust/bindings/bindings_helper.h | 1 + rust/helpers/helpers.c | 1 + rust/helpers/jump_label.c | 14 ++++++++++++++ rust/kernel/jump_label.rs | 30 ++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 5 files changed, 47 insertions(+) diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helpe= r.h index ae82e9c941af..e0846e7e93e6 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 30f40149f3a9..17e1b60d178f 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -12,6 +12,7 @@ #include "build_assert.c" #include "build_bug.c" #include "err.c" +#include "jump_label.c" #include "kunit.c" #include "mutex.c" #include "page.c" diff --git a/rust/helpers/jump_label.c b/rust/helpers/jump_label.c new file mode 100644 index 000000000000..fc1f1e0df08e --- /dev/null +++ b/rust/helpers/jump_label.c @@ -0,0 +1,14 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2024 Google LLC. + */ + +#include + +#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..4b7655b2a022 --- /dev/null +++ b/rust/kernel/jump_label.rs @@ -0,0 +1,30 @@ +// 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_la= bel.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_k= ey`. +/// +/// # Safety +/// +/// The macro must be used with a real static key defined by C. +#[macro_export] +macro_rules! static_branch_unlikely { + ($key:path, $keytyp:ty, $field:ident) =3D> {{ + let _key: *const $keytyp =3D ::core::ptr::addr_of!($key); + let _key: *const $crate::bindings::static_key_false =3D ::core::pt= r::addr_of!((*_key).$field); + let _key: *const $crate::bindings::static_key =3D _key.cast(); + + $crate::bindings::static_key_count(_key.cast_mut()) > 0 + }}; +} +pub use static_branch_unlikely; diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index b5f4b3ce6b48..708ff817ccc3 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; pub mod list; --=20 2.47.0.163.g1226f6d8fa-goog