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a=openpgp-sha256; l=9288; i=aliceryhl@google.com; h=from:subject:message-id; bh=smlzFG650Bjyj/G17d9Nx6uQENcjy/0hVqprbqaAZSk=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBmfrlw3bHKyORe0dE0EbrR0xejztmzSskCkdb1q 8YpniSF/amJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZn65cAAKCRAEWL7uWMY5 RmF6D/4s+/xnuVSiUlgtEsduacVpUm4pE1jcx/Do8fGJ9OQfkiODdmUNe7KHShGgcJff1bKG5jr J0ZxJr/GVN2vslbojoTLkBHwhCEfY/aXJcT6/dmCWylHIKd1Z8xSA4Uf0fVDCph0gmr0+3fDl+3 ND1WW57X9ZfVHYrNw53br5PavOcA/zTYzyyqoXKzUwHYXuRfPlWF+KGCAh5vHSPp+xJMUNJ9/rd xe6DRQ2I6mNjE14bZDgjixPJMnYetZDsn7OHtfGhTcxWNCeOCO+AtkETX+DPb1YywcwJQkbpBSC HT0GMYoa4klrOEj/1IL5aAtIQJjaWuqgOHYOS9+TvHqhfxBq8Zx6n4zibWP23zxPcTOyJect/An uVR+SRz9sbdH0HI2vVszXlm51cx5gNGxIFRYc81pbGbPGO6jLOvkEqPEeYUCCY5nnguSgWDqpjA 9TYpro/ubpYC45Ry9XzS2m2iHQPBaaj4QPYiKO86g1vpdUlp0+FLAoJqyu1WZNk08i8+smeXe7U 3mLF114P0UL1tpd1dwL8eOsFkoHg02AAy6IvTvcCxOR/fDqaT0blCbsr7FFTCyhuuF9EkQrNCW7 xzvTGAOLliUGNSDFfoW/wnVuxKy4GxlwizdVQnlf3CvIZug0MGICixjVL8aALVEQDDweYf5BJGG DAULc4DNwd64I9Q== X-Mailer: b4 0.13-dev-26615 Message-ID: <20240628-tracepoint-v4-1-353d523a9c15@google.com> Subject: [PATCH v4 1/2] 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, Arnd Bergmann , linux-arch@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , "Peter Zijlstra (Intel)" , 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_key_false` even though it is deprecated, so we add the same functionality to Rust. It is not possible to use the existing C implementation of arch_static_branch because it passes the argument `key` to inline assembly as an 'i' parameter, so any attempt to add a C helper for this function will fail to compile because the value of `key` must be known at compile-time. Signed-off-by: Alice Ryhl Reviewed-by: Gary Guo Tested-by: WANG Rui --- rust/kernel/arch/arm64/jump_label.rs | 34 ++++++++++++++++++++++++++++ rust/kernel/arch/loongarch/jump_label.rs | 35 +++++++++++++++++++++++++++++ rust/kernel/arch/mod.rs | 24 ++++++++++++++++++++ rust/kernel/arch/riscv/jump_label.rs | 38 ++++++++++++++++++++++++++++= ++++ rust/kernel/arch/x86/jump_label.rs | 35 +++++++++++++++++++++++++++++ rust/kernel/lib.rs | 2 ++ rust/kernel/static_key.rs | 32 +++++++++++++++++++++++++++ scripts/Makefile.build | 2 +- 8 files changed, 201 insertions(+), 1 deletion(-) diff --git a/rust/kernel/arch/arm64/jump_label.rs b/rust/kernel/arch/arm64/= jump_label.rs new file mode 100644 index 000000000000..5eede2245718 --- /dev/null +++ b/rust/kernel/arch/arm64/jump_label.rs @@ -0,0 +1,34 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Arm64 Rust implementation of jump_label.h + +/// arm64 implementation of arch_static_branch +#[macro_export] +#[cfg(target_arch =3D "aarch64")] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) =3D> {'my_label: { + core::arch::asm!( + r#" + 1: nop + + .pushsection __jump_table, "aw" + .align 3 + .long 1b - ., {0} - . + .quad {1} + {2} + {3} - . + .popsection + "#, + label { + break 'my_label true; + }, + sym $key, + const ::core::mem::offset_of!($keytyp, $field), + const $crate::arch::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +pub use arch_static_branch; diff --git a/rust/kernel/arch/loongarch/jump_label.rs b/rust/kernel/arch/lo= ongarch/jump_label.rs new file mode 100644 index 000000000000..8d31318aeb11 --- /dev/null +++ b/rust/kernel/arch/loongarch/jump_label.rs @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Loongarch Rust implementation of jump_label.h + +/// loongarch implementation of arch_static_branch +#[doc(hidden)] +#[macro_export] +#[cfg(target_arch =3D "loongarch64")] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) =3D> {'my_label: { + core::arch::asm!( + r#" + 1: nop + + .pushsection __jump_table, "aw" + .align 3 + .long 1b - ., {0} - . + .quad {1} + {2} + {3} - . + .popsection + "#, + label { + break 'my_label true; + }, + sym $key, + const ::core::mem::offset_of!($keytyp, $field), + const $crate::arch::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +pub use arch_static_branch; diff --git a/rust/kernel/arch/mod.rs b/rust/kernel/arch/mod.rs new file mode 100644 index 000000000000..14271d2530e9 --- /dev/null +++ b/rust/kernel/arch/mod.rs @@ -0,0 +1,24 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Architecture specific code. + +#[cfg_attr(target_arch =3D "aarch64", path =3D "arm64")] +#[cfg_attr(target_arch =3D "x86_64", path =3D "x86")] +#[cfg_attr(target_arch =3D "loongarch64", path =3D "loongarch")] +#[cfg_attr(target_arch =3D "riscv64", path =3D "riscv")] +mod inner { + pub mod jump_label; +} + +pub use self::inner::*; + +/// A helper used by inline assembly to pass a boolean to as a `const` par= ameter. +/// +/// Using this function instead of a cast lets you assert that the input i= s a boolean, rather than +/// some other type that can be cast to an integer. +#[doc(hidden)] +pub const fn bool_to_int(b: bool) -> i32 { + b as i32 +} diff --git a/rust/kernel/arch/riscv/jump_label.rs b/rust/kernel/arch/riscv/= jump_label.rs new file mode 100644 index 000000000000..2672e0c6f033 --- /dev/null +++ b/rust/kernel/arch/riscv/jump_label.rs @@ -0,0 +1,38 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! RiscV Rust implementation of jump_label.h + +/// riscv implementation of arch_static_branch +#[macro_export] +#[cfg(target_arch =3D "riscv64")] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) =3D> {'my_label: { + core::arch::asm!( + r#" + .align 2 + .option push + .option norelax + .option norvc + 1: nop + .option pop + .pushsection __jump_table, "aw" + .align 3 + .long 1b - ., {0} - . + .dword {1} + {2} + {3} - . + .popsection + "#, + label { + break 'my_label true; + }, + sym $key, + const ::core::mem::offset_of!($keytyp, $field), + const $crate::arch::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +pub use arch_static_branch; diff --git a/rust/kernel/arch/x86/jump_label.rs b/rust/kernel/arch/x86/jump= _label.rs new file mode 100644 index 000000000000..383bed273c50 --- /dev/null +++ b/rust/kernel/arch/x86/jump_label.rs @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! X86 Rust implementation of jump_label.h + +/// x86 implementation of arch_static_branch +#[macro_export] +#[cfg(target_arch =3D "x86_64")] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) =3D> {'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} + {3} - . + .popsection + "#, + label { + break 'my_label true; + }, + sym $key, + const ::core::mem::offset_of!($keytyp, $field), + const $crate::arch::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +pub use arch_static_branch; diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index fbd91a48ff8b..fffd4e1dd1c1 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -27,6 +27,7 @@ extern crate self as kernel; =20 pub mod alloc; +pub mod arch; mod build_assert; pub mod error; pub mod init; @@ -38,6 +39,7 @@ pub mod prelude; pub mod print; mod static_assert; +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..32cf027ef091 --- /dev/null +++ b/rust/kernel/static_key.rs @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Logic for static keys. + +use crate::bindings::*; + +/// 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`. +#[macro_export] +macro_rules! static_key_false { + ($key:path, $keytyp:ty, $field:ident) =3D> {{ + // Assert that `$key` has type `$keytyp` and that `$key.$field` ha= s type `static_key`. + // + // SAFETY: We know that `$key` is a static because otherwise the i= nline assembly will not + // compile. The raw pointers created in this block are in-bounds o= f `$key`. + static _TY_ASSERT: () =3D unsafe { + let key: *const $keytyp =3D ::core::ptr::addr_of!($key); + let _: *const $crate::bindings::static_key =3D ::core::ptr::ad= dr_of!((*key).$field); + }; + + $crate::arch::jump_label::arch_static_branch! { $key, $keytyp, $fi= eld, false } + }}; +} + +pub use 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) # ------------------------------------------------------------------------= --- =20 -rust_allowed_features :=3D new_uninit +rust_allowed_features :=3D asm_const,asm_goto,new_uninit =20 # `--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 --=20 2.45.2.803.g4e1b14247a-goog