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Thu, 06 Jun 2024 08:05:57 -0700 (PDT) Date: Thu, 06 Jun 2024 15:05:25 +0000 In-Reply-To: <20240606-tracepoint-v1-0-6551627bf51b@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240606-tracepoint-v1-0-6551627bf51b@google.com> X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=4222; i=aliceryhl@google.com; h=from:subject:message-id; bh=uHuK5cxCqNVkYxGJWDP/1f30u93vV/WBYZH9iUJYV3U=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBmYdBKoUoIL/G+5ecJleyzv9Uh17RVRQHXMZ0gd s0xAlyPxmSJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZmHQSgAKCRAEWL7uWMY5 RhvJD/9oQToFBgs8kw4XgbLrWL0zjwaOWrckWwvD8cwzPfnmq/2ghW6DoVOXs8w8J4rxycXTOjV fCXOenZ0frK62IFBwcQxpcK43worsfjN8LGzgkmFy675pdJZQOGI/HOKc7Z4yvVSp/1uWMB6tSy 2pUwJbqFzh7oKCAnHDl72zt0NmoAo6CUlPSntj7nzvhZH94zijFtT7DqjSm91WHbT+OgMRRJPTw WQqzLHjkP+u7Weg03ftuFndJGB0y0LSySMsFJ67qHYyD9R8i8jnRn44srHPu5Mt5osUX7XC3B9W WrSINyhKQOEpJ+nBmLTLJWyQo2Zlu1yFh6ODt3mT56RNXjziApotIyXnkcDpW7bGWFhw+5OtS0b Xy1JsusGh+oWIDWRFRa6JdzHQ0IPgUwWEj7zoPT6XGQFpc7Yxi4mMwBb+OEU2mbAKJ77oTSJkiG d+rGxeS0fjVx82l8Ta22js8ZQx8NmLja+wC/Q33Po2WYZoYNV5NItlLMp2wxZewMe8PdcaHpUoY 8pvQncs8ZCntY/nkhLt9BnEiUye4/5kr7HOplUPZtCd8+zFGYlGcyDw7jNf0MBXnb4LbZEwfs3A aCHDZC+ds2RxbxhUksw3YnCInW6cFgHYfBz85OgBwKaSFuWvwyylOkYFMNabqtLaIEVNgdyW8Ga 4drFLhl+VtNBx7A== X-Mailer: b4 0.13-dev-26615 Message-ID: <20240606-tracepoint-v1-2-6551627bf51b@google.com> Subject: [PATCH 2/3] rust: add 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, Alice Ryhl 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. Signed-off-by: Alice Ryhl --- rust/kernel/lib.rs | 1 + rust/kernel/static_key.rs | 87 +++++++++++++++++++++++++++++++++++++++++++++++ scripts/Makefile.build | 2 +- 3 files changed, 89 insertions(+), 1 deletion(-) diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index d534b1178955..22e1fedd0774 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -39,6 +39,7 @@ pub mod print; mod static_assert; pub mod static_call; +pub mod static_key; #[doc(hidden)] pub mod std_vendor; pub mod str; diff --git a/rust/kernel/static_key.rs b/rust/kernel/static_key.rs new file mode 100644 index 000000000000..6c3dbe14c98a --- /dev/null +++ b/rust/kernel/static_key.rs @@ -0,0 +1,87 @@ +// 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")] +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, $field), + ); + + break 'my_label false; + }}; +} + +#[doc(hidden)] +#[macro_export] +#[cfg(target_arch = "aarch64")] +macro_rules! _static_key_false { + ($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}; diff --git a/scripts/Makefile.build b/scripts/Makefile.build index efacca63c897..60197c1c063f 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -263,7 +263,7 @@ $(obj)/%.lst: $(obj)/%.c FORCE # Compile Rust sources (.rs) # --------------------------------------------------------------------------- -rust_allowed_features := new_uninit +rust_allowed_features := asm_const,asm_goto,new_uninit # `--out-dir` is required to avoid temporaries being created by `rustc` in the # current working directory, which may be not accessible in the out-of-tree