From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 2DCC41862B7; Fri, 7 Jun 2024 10:52:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717757568; cv=none; b=SvIOtYnMl1Qj6S+iqv3ySb1ku0N6nTpqzN8ghHYaknUrQd3+Pcr/R3XUv2q5i0dPuPjd+qk3Y3GwzgSdWMS6LLbE7gZ2IXQZzfghLYicuAqHzRLW7ZiiA6ovOSHO7e2fY80Dmr6iEaIbgAmplYZVhnhkpNzIBDKhDzurJUkCRXs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717757568; c=relaxed/simple; bh=3SY741i1aIiLsGZWztwjlZpBTWd8uktQ6DwDmA39LP0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rHOTcUur9KlqJQPTnOfN+74eR+eVSfjqvfGx6Q9iwnonFND3iXec1MCQiLnrBIoIhAdwKUaPsULkmXG6UXMzM4tH+uDUx+i8oPOj9fbqw2F9729+XxdYJGbRWRSeaUDdaO/rcYYdEhbmYbvKO+8A8qPZn85sX8Dw12z0zsKJ6GI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=Zk8JR6ka; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Zk8JR6ka" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=juY0wWEQb5LaFKacVEjtLjtoEwuz5HfLcwyYZHOCQWo=; b=Zk8JR6kakPe/gsurlaGxk40xu0 mkoAdiKJY9k7PVZIAOGadi7BlR8R0zYEcA9+/4pVqJEwkQbJMTKmwP0aWbDqBJrGYVz4BSRWSr5Do 6OOCTKY5AaVy0AnKtxVulTb5sI3lx8PC0gfQXIONNmopaSsrPt9rs762eRIwMiTYyKL/ZedL5fk03 o2hLpGSlRRTs6IlzJWQqEIUJIAe0asxns/fuWJZYAYrFSv093wSFk9NXz9r4vsN0cTN64P/KObQNE TqMqcducmFtsrch9WxIbBUGy3U/q48AnY3aYdCKhUL/XWtP23N08Y+HQuPHU4kTqFaK3cgg/WnQvu woHRPJxQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1sFXCy-00000005mUb-430Q; Fri, 07 Jun 2024 10:52:33 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 947B530047C; Fri, 7 Jun 2024 12:52:32 +0200 (CEST) Date: Fri, 7 Jun 2024 12:52:32 +0200 From: Peter Zijlstra To: Alice Ryhl Cc: a.hindborg@samsung.com, alex.gaynor@gmail.com, ardb@kernel.org, benno.lossin@proton.me, bjorn3_gh@protonmail.com, boqun.feng@gmail.com, gary@garyguo.net, jbaron@akamai.com, jpoimboe@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, mhiramat@kernel.org, miguel.ojeda.sandonis@gmail.com, ojeda@kernel.org, rostedt@goodmis.org, rust-for-linux@vger.kernel.org, wedsonaf@gmail.com Subject: Re: [PATCH 1/3] rust: add static_call support Message-ID: <20240607105232.GP8774@noisy.programming.kicks-ass.net> References: <20240606193318.GK8774@noisy.programming.kicks-ass.net> <20240607094329.3878781-1-aliceryhl@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240607094329.3878781-1-aliceryhl@google.com> On Fri, Jun 07, 2024 at 09:43:29AM +0000, Alice Ryhl wrote: > Peter Zijlstra wrote: > > On Thu, Jun 06, 2024 at 09:09:00PM +0200, Miguel Ojeda wrote: > > > On Thu, Jun 6, 2024 at 7:19 PM Peter Zijlstra wrote: > > > > > > > > This is absolutely unreadable gibberish -- how am I supposed to keep > > > > this in sync with the rest of the static_call infrastructure? > > > > > > Yeah, they are macros, which look different from "normal" Rust code. > > > > Macros like CPP ? > > Yes, this patch series uses declarative macros, which are the closest > that Rust has to the C preprocessor. They are powerful, but just like > CPP, they can become pretty complicated and hard to read if you are > doing something non-trivial. > > The macro_rules! block is how you define a new declarative macro. I'm sorry, but 30+ years of reading ! as NOT (or factorial) isn't going to go away. So I'm reading your macros do NOT rule. > The ($name:ident($($args:expr),* $(,)?)) part defines the arguments to > the declarative macro. This syntax means: > > 1. The input starts with any identifier, which we call $name. > 2. Then there must be a ( token. The above exaple fails, because the next token is :ident, whatever the heck that might be. Also, extra points for line-noise due to lack of whitespace. > So for example, you might invoke the macro like this: > > static_call!(tp_func_my_tracepoint(__data, &mut my_task_struct)); static_call NOT (blah dog blah); > Inside the macro, you will see things such as: > $crate::macros::paste! { $crate::bindings:: [<__SCK__ $name >]; } > > The Rust syntax for invoking a macro has an exclamation mark after the Like I said before, the creator of Rust must've been an esoteric language freak and must've wanted to make this unreadable on purpose :/ Also, why the white space beteen the :: scope operator and the [< thing? that's just weird. I would then expect the output to be: ...::bindings:: __SCK__my_static_key > name, so you know that $crate::macros::paste is a macro. The `paste` > macro just emits its input unchanged, except that any identifiers > between [< and >] are concatenated into a single identifier. So if $name > is my_static_key, then the above invocation of paste! emits: > > $crate::bindings::__SCK__my_static_key; But it doesn't, so it isn't unmodified, it seems to strip whitespace. > The $crate::bindings module is where the output of bindgen goes, so this > should correspond to the C symbol called __SCK__my_static_key. > > > > Is there something we could do to help here? I think Alice and others > > > would be happy to explain how it works and/or help maintain it in the > > > future if you prefer. > > > > Write a new language that looks more like C -- pretty please ? :-) > > > > Mostly I would just really like you to just use arm/jump_label.h, > > they're inline functions and should be doable with IR, no weirdo CPP > > involved in this case. > > I assume that you're referring to static_key_false here? I don't think > that function can be exposed using IR because it passes the function > argument called key as an "i" argument to an inline assembly block. Any > attempt to compile static_key_false without knowing the value of key at > compile time will surely fail to compile with the > > invalid operand for inline asm constraint 'i' > > error. You can have clang read the header files and compile them into Intermediate-Representation, and have it splice the lot into the Rust crap's IR and voila, compile time. You just need to extend the rust thing to be able to consume C header files.