From nobody Sun Nov 24 13:55:46 2024 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6276E1DA60F for ; Tue, 5 Nov 2024 14:19:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730816348; cv=none; b=mRpj5hR7/S+rWyGP5+fxmkj2o038M8FC0uPVB0o+KpBb7QOMPuZklK+ZWUUl2ddDlAqUaKoLHIPbM1vX0Fxvw0IyBvnqjqoEwNylzk2paZhxM4g+8VVeG2CT5YcZaG7M5S3CJnG7Nde2ACMwBCXEHFdenDiP+6EHEo/KIxtkXU8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730816348; c=relaxed/simple; bh=+hkx74GyN3lyWCzj1lro+jVsT9O8FZAkkm7VJ0l2toM=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=lSyVw/s0OoNJVJPPRFP6PVyXLpVzK4h3SJjQ4kkDqCmKwabYqKktt9OvGfpYdKMLUsMhces6UG1QAKQoty3iIfMHQXxbwAd50qYBM+CuM90cQWnMABGRgB0Cgs2snQSMysqafB2g8GXxr9yahylaPiVIcywNj2aYw1sUELUpMQY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2349BC4CEDA; Tue, 5 Nov 2024 14:19:08 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98) (envelope-from ) id 1t8KOj-00000000WkS-2P8i; Tue, 05 Nov 2024 09:19:09 -0500 Message-ID: <20241105141909.417589373@goodmis.org> User-Agent: quilt/0.68 Date: Tue, 05 Nov 2024 09:18:51 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Josh Poimboeuf , Jason Baron , Ard Biesheuvel , Alex Gaynor , Wedson Almeida Filho , Gary Guo , " =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= " , Benno Lossin , Andreas Hindborg , Arnd Bergmann , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Ryan Roberts , Fuad Tabba , Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Tianrui Zhao , "Peter Zijlstra (Intel)" , Miguel Ojeda , Boqun Feng , Alice Ryhl Subject: [for-next][PATCH 5/5] rust: add arch_static_branch References: <20241105141846.641050484@goodmis.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Alice Ryhl To allow the Rust implementation of static_key_false to use runtime code patching instead of the generic implementation, pull in the relevant inline assembly from the jump_label.h header by running the C preprocessor on a .rs.S file. Build rules are added for .rs.S files. Since the relevant inline asm has been adjusted to export the inline asm via the ARCH_STATIC_BRANCH_ASM macro in a consistent way, the Rust side does not need architecture specific code to pull in the asm. It is not possible to use the existing C implementation of arch_static_branch via a Rust helper because it passes the argument `key` to inline assembly as an 'i' parameter. 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. Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Josh Poimboeuf Cc: Jason Baron Cc: Ard Biesheuvel Cc: Alex Gaynor Cc: Wedson Almeida Filho Cc: Gary Guo Cc: " =3D?utf-8?q?Bj=3DC3=3DB6rn_Roy_Baron?=3D " Cc: Benno Lossin Cc: Andreas Hindborg Cc: Arnd Bergmann Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Sean Christopherson Cc: Uros Bizjak Cc: Catalin Marinas Cc: Will Deacon Cc: Marc Zyngier Cc: Oliver Upton Cc: Mark Rutland Cc: Ryan Roberts Cc: Fuad Tabba Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Anup Patel Cc: Andrew Jones Cc: Alexandre Ghiti Cc: Conor Dooley Cc: Samuel Holland Cc: Huacai Chen Cc: WANG Xuerui Cc: Bibo Mao Cc: Tiezhu Yang Cc: Andrew Morton Cc: Tianrui Zhao Link: https://lore.kernel.org/20241030-tracepoint-v12-5-eec7f0f8ad22@google= .com Suggested-by: Peter Zijlstra (Intel) Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Reviewed-by: Boqun Feng Signed-off-by: Alice Ryhl Signed-off-by: Steven Rostedt (Google) --- rust/Makefile | 6 ++++ rust/kernel/.gitignore | 3 ++ rust/kernel/arch_static_branch_asm.rs.S | 7 ++++ rust/kernel/jump_label.rs | 46 ++++++++++++++++++++++++- rust/kernel/lib.rs | 35 +++++++++++++++++++ scripts/Makefile.build | 9 ++++- 6 files changed, 104 insertions(+), 2 deletions(-) create mode 100644 rust/kernel/.gitignore create mode 100644 rust/kernel/arch_static_branch_asm.rs.S diff --git a/rust/Makefile b/rust/Makefile index b5e0a73b78f3..bc2a9071dd29 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -36,6 +36,8 @@ always-$(CONFIG_RUST_KERNEL_DOCTESTS) +=3D doctests_kerne= l_generated_kunit.c obj-$(CONFIG_RUST_KERNEL_DOCTESTS) +=3D doctests_kernel_generated.o obj-$(CONFIG_RUST_KERNEL_DOCTESTS) +=3D doctests_kernel_generated_kunit.o =20 +always-$(subst y,$(CONFIG_RUST),$(CONFIG_JUMP_LABEL)) +=3D kernel/arch_sta= tic_branch_asm.rs + # Avoids running `$(RUSTC)` for the sysroot when it may not be available. ifdef CONFIG_RUST =20 @@ -424,4 +426,8 @@ $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(= obj)/build_error.o \ $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE +$(call if_changed_rule,rustc_library) =20 +ifdef CONFIG_JUMP_LABEL +$(obj)/kernel.o: $(obj)/kernel/arch_static_branch_asm.rs +endif + endif # CONFIG_RUST diff --git a/rust/kernel/.gitignore b/rust/kernel/.gitignore new file mode 100644 index 000000000000..d082731007c6 --- /dev/null +++ b/rust/kernel/.gitignore @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0 + +/arch_static_branch_asm.rs diff --git a/rust/kernel/arch_static_branch_asm.rs.S b/rust/kernel/arch_sta= tic_branch_asm.rs.S new file mode 100644 index 000000000000..2afb638708db --- /dev/null +++ b/rust/kernel/arch_static_branch_asm.rs.S @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include + +// Cut here. + +::kernel::concat_literals!(ARCH_STATIC_BRANCH_ASM("{symb} + {off} + {branc= h}", "{l_yes}")) diff --git a/rust/kernel/jump_label.rs b/rust/kernel/jump_label.rs index 4b7655b2a022..2f2df03a3275 100644 --- a/rust/kernel/jump_label.rs +++ b/rust/kernel/jump_label.rs @@ -24,7 +24,51 @@ macro_rules! static_branch_unlikely { 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(); =20 - $crate::bindings::static_key_count(_key.cast_mut()) > 0 + #[cfg(not(CONFIG_JUMP_LABEL))] + { + $crate::bindings::static_key_count(_key) > 0 + } + + #[cfg(CONFIG_JUMP_LABEL)] + $crate::jump_label::arch_static_branch! { $key, $keytyp, $field, f= alse } }}; } pub use static_branch_unlikely; + +/// Assert that the assembly block evaluates to a string literal. +#[cfg(CONFIG_JUMP_LABEL)] +const _: &str =3D include!(concat!( + env!("OBJTREE"), + "/rust/kernel/arch_static_branch_asm.rs" +)); + +#[macro_export] +#[doc(hidden)] +#[cfg(CONFIG_JUMP_LABEL)] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) =3D> {'my_label: { + $crate::asm!( + include!(concat!(env!("OBJTREE"), "/rust/kernel/arch_static_br= anch_asm.rs")); + l_yes =3D label { + break 'my_label true; + }, + symb =3D sym $key, + off =3D const ::core::mem::offset_of!($keytyp, $field), + branch =3D const $crate::jump_label::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +#[cfg(CONFIG_JUMP_LABEL)] +pub use arch_static_branch; + +/// 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, and not some +/// other type that can also be cast to an integer. +#[doc(hidden)] +pub const fn bool_to_int(b: bool) -> i32 { + b as i32 +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 55f81f49024e..97286b99270e 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -148,3 +148,38 @@ macro_rules! container_of { ptr.sub(offset) as *const $type }} } + +/// Helper for `.rs.S` files. +#[doc(hidden)] +#[macro_export] +macro_rules! concat_literals { + ($( $asm:literal )* ) =3D> { + ::core::concat!($($asm),*) + }; +} + +/// Wrapper around `asm!` configured for use in the kernel. +/// +/// Uses a semicolon to avoid parsing ambiguities, even though this does n= ot match native `asm!` +/// syntax. +// For x86, `asm!` uses intel syntax by default, but we want to use at&t s= yntax in the kernel. +#[cfg(any(target_arch =3D "x86", target_arch =3D "x86_64"))] +#[macro_export] +macro_rules! asm { + ($($asm:expr),* ; $($rest:tt)*) =3D> { + ::core::arch::asm!( $($asm)*, options(att_syntax), $($rest)* ) + }; +} + +/// Wrapper around `asm!` configured for use in the kernel. +/// +/// Uses a semicolon to avoid parsing ambiguities, even though this does n= ot match native `asm!` +/// syntax. +// For non-x86 arches we just pass through to `asm!`. +#[cfg(not(any(target_arch =3D "x86", target_arch =3D "x86_64")))] +#[macro_export] +macro_rules! asm { + ($($asm:expr),* ; $($rest:tt)*) =3D> { + ::core::arch::asm!( $($asm)*, $($rest)* ) + }; +} diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 8f423a1faf50..03ee558fcd4d 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -248,12 +248,13 @@ $(obj)/%.lst: $(obj)/%.c FORCE # Compile Rust sources (.rs) # ------------------------------------------------------------------------= --- =20 -rust_allowed_features :=3D new_uninit +rust_allowed_features :=3D asm_const,asm_goto,new_uninit =20 # `--out-dir` is required to avoid temporaries being created by `rustc` in= the # current working directory, which may be not accessible in the out-of-tree # modules case. rust_common_cmd =3D \ + OBJTREE=3D$(abspath $(objtree)) \ RUST_MODFILE=3D$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \ -Zallow-features=3D$(rust_allowed_features) \ -Zcrate-attr=3Dno_std \ @@ -303,6 +304,12 @@ quiet_cmd_rustc_ll_rs =3D $(RUSTC_OR_CLIPPY_QUIET) $(q= uiet_modtag) $@ $(obj)/%.ll: $(obj)/%.rs FORCE +$(call if_changed_dep,rustc_ll_rs) =20 +quiet_cmd_rustc_rs_rs_S =3D RSCPP $(quiet_modtag) $@ + cmd_rustc_rs_rs_S =3D $(CPP) $(c_flags) -xc -C -P $< | sed '1,/^\/\/= Cut here.$$/d' >$@ + +$(obj)/%.rs: $(obj)/%.rs.S FORCE + +$(call if_changed_dep,rustc_rs_rs_S) + # Compile assembler sources (.S) # ------------------------------------------------------------------------= --- =20 --=20 2.45.2