From patchwork Fri Oct 11 10:13:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alice Ryhl X-Patchwork-Id: 13832323 Received: from mail-ej1-f74.google.com (mail-ej1-f74.google.com [209.85.218.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1ED42215023 for ; Fri, 11 Oct 2024 10:14:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728641669; cv=none; b=kHbwcfAYPlnK8RlUOoOBni0g8S/nk27jtkU0I3xqJjFQ8tqZRKz+8mC7Iq9qSmijmbg8X/vH99jmwCEkD0qWT9t8wh008tbYQedCsnweGZb8SlUR9/M0ZeS2VhYv2tjAr2J9MempUiHnqCOeLvSD+Zz+CislaSyu/ELR/eQA7ew= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728641669; c=relaxed/simple; bh=OvzSr4VFrX1KtK2UXFthBCdVxqArCAH6SA7+jizJ+V0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=QvfqVIL8wYN9xwxNzD1pg6eFRnxn+URrx90/0VDoTqTr2IoebRN1hgO8naHPno83ufhQ5jLg7GQ4vvPfNQrFoQ886HG4KUuaOaI9nNhTG+UiMoYDI9/eKOofNKRK0LWaUG1aIEGbI5NpqJNCG/1oxUZ1Sx0BeQKlwI7TZem8Ugs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=egA9DfFj; arc=none smtp.client-ip=209.85.218.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="egA9DfFj" Received: by mail-ej1-f74.google.com with SMTP id a640c23a62f3a-a9951711adeso147463766b.0 for ; Fri, 11 Oct 2024 03:14:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1728641665; x=1729246465; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=dXlYt/oa+7NEzDWWVPyKVNY96AVLFROe93mGWbsR7r0=; b=egA9DfFjuYqG4OjbDW7n0FqIBWgDiXG3mluYtahjo+wrjQg3sxwQnN317fw5KimA72 TPQzI/96Y/iRXShWMdHtExoaxaXlB8Aro/RbRRyW23lwoWLOXoInzQMZ2fiSjcj9PBR0 bWhiG1sqkp2a9do1/+yEg+8nhh8aUG0g+WLqkSj0781UYm4KlQuti2nA+Vji2oQRZANW 8Mud4z2E03aA44mDkBKGdaBHGbjn5MRV6RSQly9DLOkTC7ZJYTlSE9HqqaR+NTwwQi5T VFj2HWNDPHRFnPjz1YBeQ4xDfdHVsfDRqVzaxsHtOHQbqRO1SVKrXOo88Vwp5b0tPTxV m+Rg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728641665; x=1729246465; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=dXlYt/oa+7NEzDWWVPyKVNY96AVLFROe93mGWbsR7r0=; b=I6+Kd3ABKa0DF73ziatRtO9SpmHAIZucw8BVIP2AmilgbOmYr2MR5hJ1O3WLpdulS7 QU+wOfDWHkMISusvs1RM3bTgLrAMYXvPGFS+cMcQSkpFakmI1FqWOth9LxjrWxWx1gQo 9U4ds9nyG2ZBcyUfJnb0x5xFtnaIJ/5LUHcZvEgOUfpx54k6I+AnLN+7Y69a+sNUNzEi VEAJ0jS3eWSiD3iKX83WVYlCToTKTqZBK/rRZqfLHHps8vxpiNcxwQJdZfPwhz4cy/Wf AVd2QSAOgK/r16qbqF+mwxmFQRyp3Jaq8wJAi+lMMo0NLrjX5TjacMQniZVUnqBxri5z RHxQ== X-Gm-Message-State: AOJu0Yy/13VBPQx5t8rjbqjVRUjlgX78BA7G3mROeqiVk2YHfEh1Fiv4 VMwEfMJOhkZ+pXX4lgf2JtyVkp8uqcRMJ6YRMZZF73QM+O4OfJ8iExChC51Zh1pMuJIyAleKHlZ BpDWjnDka7xvHkg== X-Google-Smtp-Source: AGHT+IFUZk2XvsvMj6Wc3yCHDL1hoT/VWhngxWmpV68U6xzKMORLk/rDkjmoUsncuiuiUYkc5ZtZnBPBoMLMN2Q= X-Received: from aliceryhl.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:35bd]) (user=aliceryhl job=sendgmr) by 2002:a17:907:7e8e:b0:a99:3a34:5cae with SMTP id a640c23a62f3a-a99b92d148emr46766b.2.1728641665077; Fri, 11 Oct 2024 03:14:25 -0700 (PDT) Date: Fri, 11 Oct 2024 10:13:38 +0000 In-Reply-To: <20241011-tracepoint-v10-0-7fbde4d6b525@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241011-tracepoint-v10-0-7fbde4d6b525@google.com> X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=8525; i=aliceryhl@google.com; h=from:subject:message-id; bh=OvzSr4VFrX1KtK2UXFthBCdVxqArCAH6SA7+jizJ+V0=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBnCPpx+Q1CTMK1zq1TvBDRV65hgxAf2+JhbNWSq 9VSnEym5kWJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZwj6cQAKCRAEWL7uWMY5 RqAlEACRKcilZAk3daKUNVB69XPd0ba36+SjExxjWIeNqFcCXa/txKr36QlmH0UAaoHDzHjqlVh xQTBWY9Iey+UMsJ9H78It7nCP53ylbcZd5YV2U2QZMxAdmKiP6ZF4aG0GZGx9MmlcCxtFsD+B1x X72KQi90T94oyyMiyTWI0i7vEx5FWYljYDU7OVCvEtVrHqdqxEa/XVGGmzt0xGM6HZ0R6Fqle7h uaHZyn5XOwLJ9jlfpdVCpold8x1IJDwx1NzokTVEWLPIISmdsKw76UumqYFiMth9FELCCH5h9zd ZiDQACwvtCFi4UShoCsTNEdmkg7KQPYbu9ZWYTeAgi1bnEHkzDh6iNHrhM2kydaC155iwO0QEu+ zfOZUWbqiH2+a6TCzPHdOuQCzmxmfY+FkA+OeIVQKREERe92SXetc2I1QRcKEheJ+Rl79bjqvGI Dc4DiMB/QxGOxKVe3WpJHHGZWKnf/+sYEr8a78usmQqkrgCx2mToZQLvkWKgVM/laa5oag1bAkZ rqwH/jNzMoaVXsfbEGVByX+kwbZmBtPcAWr9/guV1Y9/jHEKYONhQTkudCU2/gSBAuYym/Xf2S/ v4+uEtlf0wCnoKx5eSSu8WciQvPYrAHT8dpj2PYinx13xVhv/4c9sGWGN+tfIiFrZ0Ylc5Ck25p PXXvORodchFSF4A== X-Mailer: b4 0.13.0 Message-ID: <20241011-tracepoint-v10-5-7fbde4d6b525@google.com> Subject: [PATCH v10 5/5] rust: add arch_static_branch 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 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. Suggested-by: Peter Zijlstra (Intel) Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Signed-off-by: Alice Ryhl --- rust/Makefile | 5 ++- rust/kernel/.gitignore | 3 ++ rust/kernel/arch_static_branch_asm.rs.S | 7 ++++ rust/kernel/jump_label.rs | 64 ++++++++++++++++++++++++++++++++- rust/kernel/lib.rs | 35 ++++++++++++++++++ scripts/Makefile.build | 9 ++++- 6 files changed, 120 insertions(+), 3 deletions(-) diff --git a/rust/Makefile b/rust/Makefile index b5e0a73b78f3..09ea07cc4001 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -36,6 +36,8 @@ always-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.c obj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated.o obj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.o +always-$(subst y,$(CONFIG_RUST),$(CONFIG_JUMP_LABEL)) += kernel/arch_static_branch_asm.rs + # Avoids running `$(RUSTC)` for the sysroot when it may not be available. ifdef CONFIG_RUST @@ -421,7 +423,8 @@ $(obj)/uapi.o: $(src)/uapi/lib.rs \ $(obj)/kernel.o: private rustc_target_flags = --extern alloc \ --extern build_error --extern macros --extern bindings --extern uapi $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \ - $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE + $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o \ + $(obj)/kernel/arch_static_branch_asm.rs FORCE +$(call if_changed_rule,rustc_library) 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_static_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} + {branch}", "{l_yes}")) diff --git a/rust/kernel/jump_label.rs b/rust/kernel/jump_label.rs index 4b7655b2a022..cbd0ec00f0c5 100644 --- a/rust/kernel/jump_label.rs +++ b/rust/kernel/jump_label.rs @@ -24,7 +24,69 @@ macro_rules! static_branch_unlikely { let _key: *const $crate::bindings::static_key_false = ::core::ptr::addr_of!((*_key).$field); let _key: *const $crate::bindings::static_key = _key.cast(); - $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, $field, false } }}; } pub use static_branch_unlikely; + +/// Assert that the assembly block evaluates to a string literal. +#[cfg(CONFIG_JUMP_LABEL)] +const _: &str = include!(concat!(env!("OBJTREE"), "/rust/kernel/arch_static_branch_asm.rs")); + +#[macro_export] +#[doc(hidden)] +#[cfg(CONFIG_JUMP_LABEL)] +#[cfg(not(CONFIG_HAVE_JUMP_LABEL_HACK))] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) => {'my_label: { + $crate::asm!( + include!(concat!(env!("OBJTREE"), "/rust/kernel/arch_static_branch_asm.rs")); + l_yes = label { + break 'my_label true; + }, + symb = sym $key, + off = const ::core::mem::offset_of!($keytyp, $field), + branch = const $crate::jump_label::bool_to_int($branch), + ); + + break 'my_label false; + }}; +} + +#[macro_export] +#[doc(hidden)] +#[cfg(CONFIG_JUMP_LABEL)] +#[cfg(CONFIG_HAVE_JUMP_LABEL_HACK)] +macro_rules! arch_static_branch { + ($key:path, $keytyp:ty, $field:ident, $branch:expr) => {'my_label: { + $crate::asm!( + include!(concat!(env!("OBJTREE"), "/rust/kernel/arch_static_branch_asm.rs")); + l_yes = label { + break 'my_label true; + }, + symb = sym $key, + off = const ::core::mem::offset_of!($keytyp, $field), + branch = const 2 | $crate::jump_label::bool_to_int($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` parameter. +/// +/// Using this function instead of a cast lets you assert that the input is 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..c0ae9ddd9468 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -148,3 +148,38 @@ macro_rules! container_of { ptr.sub(offset) as *const $type }} } + +/// Helper for `.rs.S` files. +#[doc(hidden)] +#[macro_export] +macro_rules! concat_literals { + ($( $asm:literal )* ) => { + ::core::concat!($($asm),*) + }; +} + +/// Wrapper around `asm!` configured for use in the kernel. +/// +/// Uses a semicolon to avoid parsing ambiguities, even though this does not match native `asm!` +/// syntax. +// For x86, `asm!` uses intel syntax by default, but we want to use at&t syntax in the kernel. +#[cfg(target_arch = "x86_64")] +#[macro_export] +macro_rules! asm { + ($($asm:expr),* ; $($rest:tt)*) => { + ::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 not match native `asm!` +/// syntax. +// For non-x86 arches we just pass through to `asm!`. +#[cfg(not(target_arch = "x86_64"))] +#[macro_export] +macro_rules! asm { + ($($asm:expr),* ; $($rest:tt)*) => { + ::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: $(obj)/%.c FORCE # Compile Rust sources (.rs) # --------------------------------------------------------------------------- -rust_allowed_features := new_uninit +rust_allowed_features := asm_const,asm_goto,new_uninit # `--out-dir` is required to avoid temporaries being created by `rustc` in the # current working directory, which may be not accessible in the out-of-tree # modules case. rust_common_cmd = \ + OBJTREE=$(abspath $(objtree)) \ RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \ -Zallow-features=$(rust_allowed_features) \ -Zcrate-attr=no_std \ @@ -303,6 +304,12 @@ quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@ $(obj)/%.ll: $(obj)/%.rs FORCE +$(call if_changed_dep,rustc_ll_rs) +quiet_cmd_rustc_rs_rs_S = RSCPP $(quiet_modtag) $@ + cmd_rustc_rs_rs_S = $(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) # ---------------------------------------------------------------------------