From patchwork Sun Sep 15 14:31:28 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alice Ryhl X-Patchwork-Id: 13804817 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (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 BBC501C7B9E for ; Sun, 15 Sep 2024 14:31:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726410703; cv=none; b=C2R5vUbaQFpCrlgwslca7Koozjb4oVDwHi2Gy+79EnVbHdzrvGFMjnNwH9HvuPsjsL2Mu+F9GUH2bbD9qnmOzo8XI5UoblvLUCAxioTMQh0z4woUA6bMTkiS0hFmDSqET8zsyorwREBNAG7us3jlGsM0Ws8jMw3u1REwpY+15mg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726410703; c=relaxed/simple; bh=+rv6j785B2Asd3auywHXoPFhTSP9gSiszdqm+Xwr+aI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=XHnZwUMAWFnFtQC2tlYaHYfFv4S5pUUcUzYvEv5tUdfRCesftrra7vHgD2SJSQd4l22LBJ4CbY63PySrHK1lpEivXteqGOE/wSU9dcdcXyrRiE6m4VgmICFx56XCBQlks7SgXi3+F8n1nnklu8yoylpzZM+Trp+a/mwNV/vWmcE= 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=Jb45IT8C; arc=none smtp.client-ip=209.85.128.201 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="Jb45IT8C" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-6d683cfa528so86380797b3.0 for ; Sun, 15 Sep 2024 07:31:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1726410701; x=1727015501; 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=GkGmu1Ei8yfm/3eeEHU7BES63iCYbdgu3tOlhcgG6qc=; b=Jb45IT8CZx81WPkfxtHNPac4UK/a1cqOQfGL8i1cfYDnku8c0wa0tDgt85RsQbTBwy 7TIBbr8YAjOVQVI3/Jj6Q7ZPEOBTLLWZuRXhAPiQTbI0Zxub8c5xFyuYb7GFDtMXwDnr MDrm92MTEfIbLd6oOqcB0+s1bB49SjhxSgS7c/qQGJlEQGG39dPkOVFA+fUVNUeC6SPy jIzy+wSsZW8n9Yn0i6fk6x0TXvpjouOvE+P4Uoi+Dx332NxOdhX1RqNd+M+KOi5QyI9C sSs11zJcOaLdFmNlLQqbXPMLHlDGd5rR2sl/Dh+TZP6vLfjC7z9N4yccgz4Q+bsGR8QI S4Mg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726410701; x=1727015501; 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=GkGmu1Ei8yfm/3eeEHU7BES63iCYbdgu3tOlhcgG6qc=; b=ZywMab4sqz+BZzXhBsCArl7tUUN5AitmHc9oglpuUxN8F/m6S1owiDJ5nRQ8JP1Ai5 V0JovkcAsjTuJnV+Udr5Z1nUfM/6EGh6nyUhLohkJxqsk/7LZP3eBO/6ZJbIaRKL26nn 6689fUzWiVrf65ObUBg4YljmxhJT8POiHitkIfxh8rnEq98PRP2usQozBzyoS4aN3bOZ ovLpTx8ELl7+mD3/9HFeFd8zggxA4I+oHSacVanRyk5Ls9shL/7FF/zxfezfrbrary/K 0Jp/Gh34GA0As+jNGY9OBhML4eUxo0yuVaPyweFDALZtWbXhex4BHwK9bnJfedtMTCC4 9PsQ== X-Forwarded-Encrypted: i=1; AJvYcCV4oqLS/qeyUJPadzkJQPb4kt2HQ22F0InUG42QGKHNWfv5cJOPAiol9agfAtipYgneDj0XMN/OKF6IRgok@vger.kernel.org X-Gm-Message-State: AOJu0YwfKYLTzR8jDWp4SZsYvzC5xH3FeGUkrOfGLULQhpK3UjvCtNKc tfQh8o0WFblhc+iYQ4NKADFzOmoiLLPtKmaFg16OIWUtqlY9hGxGwjZr+0lno4TM7tDhBcfGfCg U8r/6c2WVQ2iNVg== X-Google-Smtp-Source: AGHT+IG4OTgHmcvBK8F9QzTwC03FC+JTINJZBl77CjBGWn4GOyO6KrG4A+heQeQ8GzPto43BxFkbBmHwFjwkG2U= X-Received: from aliceryhl.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:35bd]) (user=aliceryhl job=sendgmr) by 2002:a05:690c:2a84:b0:6dc:97eb:ac51 with SMTP id 00721157ae682-6dc97ebb066mr126177b3.3.1726410700520; Sun, 15 Sep 2024 07:31:40 -0700 (PDT) Date: Sun, 15 Sep 2024 14:31:28 +0000 In-Reply-To: <20240915-alice-file-v10-0-88484f7a3dcf@google.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240915-alice-file-v10-0-88484f7a3dcf@google.com> X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=2424; i=aliceryhl@google.com; h=from:subject:message-id; bh=+rv6j785B2Asd3auywHXoPFhTSP9gSiszdqm+Xwr+aI=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBm5u/BRMuTCyk4C6ZuOxyOE1rsDuBB+ojWrrpQ7 PNWWdayP9iJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZubvwQAKCRAEWL7uWMY5 RvcUEACs+EHYmHyTXA5CqOjIpJvfFFGznoKIRV7P3FdTem4anQN4Ip2U7U3SZN3Seu9w4aN4VEf 9g73ONo8cEtyAa7AtlANEITVYf1+VtOkCqeqccGBlxyppfxFNCFTpIlfWdPMjgcvH/iDpDOeeeu Oz6HV80N4RS59/OODeu9KWfeFJIEoQTwwbagT+tUm2sYLr8gC094BqW6oY4Q9VHpiR9JzqQH2u8 YrHb4haDPSoeqTgjWGopNeXPzhssSkhxCA3u0aVlTPddRk9/gVXUv4pd12zaOyhPBfVRf+HzOeH m/7rczLTAgWjuD4EqgYErA18aJoP884SIEKcZgVFyqVth8qlvsx2dYGPAnhFPNH2GwgpXGNQmqb UjnmyLxWtSdO0v8yqs/g7hiCuE6uNVrxx2jFloTnzE/zLRICU/G2UlQXCG6aUBo6vuC3imFrbd2 XlajUVNWFG+L255yZF4Z5EYZgOP6VJm3ek63qWXGOjt+APpL6cqeGAKUJ2FSwjkhZb3PmYJ41kT qbcH+yWIIfjd3d7aaS4XNryMFCZ62ehb5zh3hid98wXk6DqSN0lowmhQYnqGYaQ7DQaGpUlsDZ8 BKzaSuu1qhgp2+OUlQJTiWw92LZm+rNv6xrJIvPnmI8R+lxbio5FS3pQypLJkIBjhAr3JiIcYK1 b71SAxy8IikXF+g== X-Mailer: b4 0.13.0 Message-ID: <20240915-alice-file-v10-2-88484f7a3dcf@google.com> Subject: [PATCH v10 2/8] rust: task: add `Task::current_raw` From: Alice Ryhl To: Paul Moore , James Morris , "Serge E. Hallyn" , Miguel Ojeda , Christian Brauner Cc: Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , " =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= " , Benno Lossin , Andreas Hindborg , Peter Zijlstra , Alexander Viro , Greg Kroah-Hartman , " =?utf-8?q?Arve_Hj=C3=B8?= =?utf-8?q?nnev=C3=A5g?= " , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan , Dan Williams , Matthew Wilcox , Thomas Gleixner , Daniel Xu , Martin Rodriguez Reboredo , Trevor Gross , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alice Ryhl , Kees Cook Introduces a safe function for getting a raw pointer to the current task. When writing bindings that need to access the current task, it is often more convenient to call a method that directly returns a raw pointer than to use the existing `Task::current` method. However, the only way to do that is `bindings::get_current()` which is unsafe since it calls into C. By introducing `Task::current_raw()`, it becomes possible to obtain a pointer to the current task without using unsafe. Link: https://lore.kernel.org/all/CAH5fLgjT48X-zYtidv31mox3C4_Ogoo_2cBOCmX0Ang3tAgGHA@mail.gmail.com/ Reviewed-by: Benno Lossin Reviewed-by: Martin Rodriguez Reboredo Reviewed-by: Trevor Gross Reviewed-by: Gary Guo Signed-off-by: Alice Ryhl --- rust/kernel/task.rs | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs index 278c623de0c6..367b4bbddd9f 100644 --- a/rust/kernel/task.rs +++ b/rust/kernel/task.rs @@ -97,6 +97,15 @@ unsafe impl Sync for Task {} type Pid = bindings::pid_t; impl Task { + /// Returns a raw pointer to the current task. + /// + /// It is up to the user to use the pointer correctly. + #[inline] + pub fn current_raw() -> *mut bindings::task_struct { + // SAFETY: Getting the current pointer is always safe. + unsafe { bindings::get_current() } + } + /// Returns a task reference for the currently executing task/thread. /// /// The recommended way to get the current task/thread is to use the @@ -119,14 +128,12 @@ fn deref(&self) -> &Self::Target { } } - // SAFETY: Just an FFI call with no additional safety requirements. - let ptr = unsafe { bindings::get_current() }; - + let current = Task::current_raw(); TaskRef { // SAFETY: If the current thread is still running, the current task is valid. Given // that `TaskRef` is not `Send`, we know it cannot be transferred to another thread // (where it could potentially outlive the caller). - task: unsafe { &*ptr.cast() }, + task: unsafe { &*current.cast() }, _not_send: NotThreadSafe, } }