From patchwork Fri Jun 28 13:23:30 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alice Ryhl X-Patchwork-Id: 13716138 Received: from mail-lf1-f74.google.com (mail-lf1-f74.google.com [209.85.167.74]) (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 A93E31BE256 for ; Fri, 28 Jun 2024 13:24:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719581049; cv=none; b=LvgKleQUwiOQ+CxxOcl0/pN5mjYFsLfXFyTlj0X2mbsJSz0Xc2D33DeiSd+TrqUxWKEVhzXbf+kf51aXSdcsE+RYVHflknLPHrXkn0C2E622ImOcQ5H3H2EluPHCAjdNd4aJEQC5MyrWz3MCM0JNrrdJ9yPgBwqmm9vxxMubk6c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719581049; c=relaxed/simple; bh=hzMKCUkrpzkRAGO9VQJLlq3A2y9r17X3xIBP4Vh3xGY=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=W6wTVSl6raHYDwP6SKnJRI/0WxTb/gtBPJVtq7tAhGp5qpCPfdV5qkr0YjydLXEBY02OlvkTUB6VMq0gaJ6wul09Zf+qd8hKglqJQsOabRe44oTsB8brQbib+mVQ49P82TPJPPi2enaG1OzBRc8nzaBgBWIpkpVV79EqFzNzPE0= 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=LCBVeg1f; arc=none smtp.client-ip=209.85.167.74 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="LCBVeg1f" Received: by mail-lf1-f74.google.com with SMTP id 2adb3069b0e04-52cdd05fec8so650937e87.0 for ; Fri, 28 Jun 2024 06:24:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1719581045; x=1720185845; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=XZuc0ScsA+/koJOZcfg/TO9U75OyrluCKQ0mW+6QsHY=; b=LCBVeg1f3T/T5q9FOliIgwEzrlzYsrztTJJyUcmfpDO1bzorVMYZE8X8KWN2Z+6mkv OiN/pqP1y+fh/DImWf9V/HAnRiqW6GPuelCLVw+mDPhrPlS66fg+7MDmUaxdxmUdv6oI vKcmhiE9itOBYZO9SUwaCGtMXsXJQC4+PmDXShP+3b8w2ihA42Y1iHjOBB9cCo7vELyB nkVsZvLsOlM9IKE5qdgOUmtZpNZNaIZe+39ViLyg8cl6qEB3jDWGoNFewsY3UEfGRdgs 05evw4lWA1/jX6+1WhkKcF02DXHOPnQtcw3bHTezu1nRGN5UClb417JIU7c70KvAVdqg +fVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719581045; x=1720185845; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=XZuc0ScsA+/koJOZcfg/TO9U75OyrluCKQ0mW+6QsHY=; b=pzVMEZVcQVjgYcu72YTzb0tA93+ssPrusCkt1s7aDla+9/PRzGDhLO01OrLNF4QDPM O0w7E1O7p1bWE58TNKaI1TiLE7aR3J8M0W3AQALvDlJwSNFnPLoWjvyN/knuM3ZEr+nv XcXJ/Eh6qVxu09istcwf1oEZ+LOAXX9NDlqXWrWP3cbOdzes0hmwSy8jwhUXKUCrc2tz 5v9Nh+ODkwXkACGY5CnYym0kCSSrIkp1Te6BWeINsR5jaV4Fa8dtz+DvBQJYKKC2zc5Z kQcD092K7uAeuu1mdmviQ3FZlcEgT6my7W81Ggwy0erpfiQhXcIBvNnUPQBDVbIP+qUw uhFg== X-Gm-Message-State: AOJu0YwouMtRZpbf16PAflEidErTzRiu/HYbaUX3xWv92GDngJ99EmkP emjk+sRwS0oooxd6QHFV+88g0BsOHHky7z//e/sl1pDxJ+D/QDfd1MbNDmmgnhmoE9d4oNCOa/x aV948INMfDhzbJw== X-Google-Smtp-Source: AGHT+IE3s//RYh2BQPLm30cB/Ms2Ha0xC/ghnkwEKFAjhQY+6EEvGjCjw7x+BTYon4IlDQWqeM7sWCMGUVZNEmI= X-Received: from aliceryhl2.c.googlers.com ([fda3:e722:ac3:cc00:68:949d:c0a8:572]) (user=aliceryhl job=sendgmr) by 2002:a05:6512:334d:b0:52e:7030:fc6c with SMTP id 2adb3069b0e04-52e7030fe47mr5341e87.7.1719581044824; Fri, 28 Jun 2024 06:24:04 -0700 (PDT) Date: Fri, 28 Jun 2024 13:23:30 +0000 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAFO5fmYC/23MSw6CMBSF4a2Qjq3p7Qt05D6MgxYu0EQpaUmjI ezdwgiiw3OS759JxOAwkmsxk4DJReeHPOSpIHVvhg6pa/ImnHHJNNN0CqbG0bthogIQlL0wlCW QDMaArXtvsfsj797FyYfP1k6wvn8zCSijWinQvLStAnvrvO+eeK79i6ydxHcW2MHybFuD1jQVW KHUjxU7y+FgRbYXlBIRDbfV0S7L8gWd4iEZHQEAAA== X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=4798; i=aliceryhl@google.com; h=from:subject:message-id; bh=hzMKCUkrpzkRAGO9VQJLlq3A2y9r17X3xIBP4Vh3xGY=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBmfrlotXVffeRQRKmrpCRkQR9ZrzcTwpekmobmU hNI4tnCMOmJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZn65aAAKCRAEWL7uWMY5 RsFBD/9DKLutdOjG7/ZJI58IPTulEbu48TdU6ZyV/vYvd8zD8bbqyQNkfDF1tzG6cHhCWq5YL8D kowOvXjKKQdJtflNTYxJANR3G1aae/i87+LlNcZNZO3byBu38FT0TNoxhHFRIIW80ucAuqQxwlA nrMmUqAyOWlkOLxmPN3WexWqQyaQAVuBSe3kzxEXSLwYM8INtmrPVLfQrowQi3D6AIJT6WpDl2n jY+eCHzQKAH0Aj7xy3EY5c1D4gM0qrhDoEhmy6TI12aFUddDtj371ObSa7HgXNBzl5cTFNS8FzF jZuCIVsIHyCv2kPeIl4y9wZS1jlNagSdu1i1ldGstuNWjbJsQ6FCsZX9IdR4vNSaJS8pSHD1q7D pOrakf6f5CqbjFbGcXXaNL4siCs/M94wYjmcPLto9pkJSPeDuCnrIpm+7rvUFG0Ev2F6lSVazAP OPAfx8p6Z2lYOerI8jdVDaA7uPl75817hzdbSJSg2Q/Z5j+ZjfY0/w7hxjvoFmYAel6Xbu9Wj+I kkX6m6xwDYo5JqRT7E6pmia7xUvFw/NLfrV4qpESjb8fAdShSQsUoi0OpICpS4FsO5lqvNIfS6+ 5GNs7DNrSlY+EgemU91Ph8ODIzA+MnA8k+wgkZkkmgkpuuLgodqR2E2WBoi9Iv9OBlHsm8PivKf g8A4yhIBuRyXNig== X-Mailer: b4 0.13-dev-26615 Message-ID: <20240628-tracepoint-v4-0-353d523a9c15@google.com> Subject: [PATCH v4 0/2] Tracepoints and static branch in Rust 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 An important part of a production ready Linux kernel driver is tracepoints. So to write production ready Linux kernel drivers in Rust, we must be able to call tracepoints from Rust code. This patch series adds support for calling tracepoints declared in C from Rust. To use the tracepoint support, you must: 1. Declare the tracepoint in a C header file as usual. 2. Add #define CREATE_RUST_TRACE_POINTS next to your #define CREATE_TRACE_POINTS. 2. Make sure that the header file is visible to bindgen. 3. Use the declare_trace! macro in your Rust code to generate Rust functions that call into the tracepoint. For example, the kernel has a tracepoint called `sched_kthread_stop`. It is declared like this: TRACE_EVENT(sched_kthread_stop, TP_PROTO(struct task_struct *t), TP_ARGS(t), TP_STRUCT__entry( __array( char, comm, TASK_COMM_LEN ) __field( pid_t, pid ) ), TP_fast_assign( memcpy(__entry->comm, t->comm, TASK_COMM_LEN); __entry->pid = t->pid; ), TP_printk("comm=%s pid=%d", __entry->comm, __entry->pid) ); To call the above tracepoint from Rust code, you must first ensure that the Rust helper for the tracepoint is generated. To do this, you would modify kernel/sched/core.c by adding #define CREATE_RUST_TRACE_POINTS. Next, you would include include/trace/events/sched.h in rust/bindings/bindings_helper.h so that the exported C functions are visible to Rust, and then you would declare the tracepoint in Rust: declare_trace! { fn sched_kthread_stop(task: *mut task_struct); } This will define an inline Rust function that checks the static key, calling into rust_do_trace_##name if the tracepoint is active. Since these tracepoints often take raw pointers as arguments, it may be convenient to wrap it in a safe wrapper: mod raw { declare_trace! { fn sched_kthread_stop(task: *mut task_struct); } } #[inline] pub fn trace_sched_kthread_stop(task: &Task) { // SAFETY: The pointer to `task` is valid. unsafe { raw::sched_kthread_stop(task.as_raw()) } } A future expansion of the tracepoint support could generate these safe versions automatically, but that is left as future work for now. This is intended for use in the Rust Binder driver, which was originally sent as an RFC [1]. The RFC did not include tracepoint support, but you can see how it will be used in Rust Binder at [2]. The author has verified that the tracepoint support works on Android devices. This implementation implements support for static keys in Rust so that the actual static branch happens in the Rust object file. However, the __DO_TRACE body remains in C code. See v1 for an implementation where __DO_TRACE is also implemented in Rust. Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-0-08ba9197f637@google.com/ [1] Link: https://r.android.com/3119993 [2] Signed-off-by: Alice Ryhl --- Changes in v4: - Move arch-specific code into rust/kernel/arch. - Restore DEFINE_RUST_DO_TRACE at end of define_trace.h - Link to v3: https://lore.kernel.org/r/20240621-tracepoint-v3-0-9e44eeea2b85@google.com Changes in v3: - Support for Rust static_key on loongarch64 and riscv64. - Avoid failing compilation on architectures that are missing Rust static_key support when the archtectures does not actually use it. - Link to v2: https://lore.kernel.org/r/20240610-tracepoint-v2-0-faebad81b355@google.com Changes in v2: - Call into C code for __DO_TRACE. - Drop static_call patch, as it is no longer needed. - Link to v1: https://lore.kernel.org/r/20240606-tracepoint-v1-0-6551627bf51b@google.com --- Alice Ryhl (2): rust: add static_key_false rust: add tracepoint support include/linux/tracepoint.h | 18 +++++++++++- include/trace/define_trace.h | 12 ++++++++ rust/bindings/bindings_helper.h | 1 + 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 | 3 ++ rust/kernel/static_key.rs | 32 ++++++++++++++++++++++ rust/kernel/tracepoint.rs | 47 ++++++++++++++++++++++++++++++++ scripts/Makefile.build | 2 +- 12 files changed, 279 insertions(+), 2 deletions(-) --- base-commit: 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0 change-id: 20240606-tracepoint-31e15b90e471 Best regards,