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 22344149DE8 for ; Mon, 2 Jun 2025 22:02:02 +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=1748901724; cv=none; b=LUXQIm/8gD2y5u4JQ5rO+uSwk95OGqDYS0NjidzdCFIu7TtkpIbRbEAawac1YFFQxXAvb/VBgodYwdSTic5HCEStaLfy8qd7XS68c5X/RhaXV4o7AOOA1YVvbwiid3jUnBdjXm/OHqFaiZiUFYPYbAztAk0uRWo2SdBFnpIx0Kc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748901724; c=relaxed/simple; bh=Mv5iFeSBDQ4HpRCbLwgsBr3jD1X4/dJVa4lZzdSh9SI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c9/1xI0F7aYD1RIqGFPy7iTKnZayOBn+ToAKFrKrLreMtuSdVeFr7pgaGYr55dn/je3IXtsocJZKPa6Xpi1/tWfvcKHdVYvkMe8LIHwA+E02PoC430PjEIcMSjGwSmwKwQESUBOx+vHM2YxLmN8dK93Y0Lr+MvihdeR4AII66FE= 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=owLZvVAt; 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="owLZvVAt" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=nUXp/MV3fY4GYnrtE7gJdbv5PETvJ8TzofAY5i/vg6A=; b=owLZvVAttMLMcPqW+Vj2VJAEce bOJp3Fbi8phyObUYFvMs3H60i/YkkPuPzrMDEfF+Rk8y+6IH0mcS3qV/x0i08/+HluMvI96VH5xHe 4ha1icNZnsqpata4lCSd5U9iCLVhAydq3WQvjN1EWbTSXNA4gGkdVWVaGq3phPtfkFcKmij5UQao+ ASNo4aHg8mE7D+6V6wtkoyVpRUsDhEiTMAGJqUuFFVXALa0Ls+3UtR8E+S82E12ALKC2HC+jKaBph CKJvRAlldSoesUwKV2R/RSI3kilmPkqNkE4gMI1c8hBupz8ZwL5/X9fs/KzWHixrPwHV/isiBjU0m X7Ge9J3Q==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uMDEG-00000001N0y-2Q75; Mon, 02 Jun 2025 22:02:00 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 24D54300787; Tue, 3 Jun 2025 00:02:00 +0200 (CEST) Date: Tue, 3 Jun 2025 00:01:59 +0200 From: Peter Zijlstra To: Linus Torvalds Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kees@kernel.org, acarmina@redhat.com, jpoimboe@kernel.org, mark.rutland@arm.com Subject: Re: [RFC 6/8] x86_64/bug: Implement __WARN_printf() Message-ID: <20250602220159.GB39782@noisy.programming.kicks-ass.net> References: <20250602144201.301974933@infradead.org> <20250602144755.928750774@infradead.org> <20250602154943.GB30486@noisy.programming.kicks-ass.net> <20250602215725.GA39782@noisy.programming.kicks-ass.net> 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=us-ascii Content-Disposition: inline In-Reply-To: <20250602215725.GA39782@noisy.programming.kicks-ass.net> On Mon, Jun 02, 2025 at 11:57:25PM +0200, Peter Zijlstra wrote: > On Mon, Jun 02, 2025 at 09:38:09AM -0700, Linus Torvalds wrote: > > > And no, I'm not ok with only using 'objdump' and friends to look at > > assembly generation. I want to be able to do > > > > make xyz.s > > > > and look at code generation without throwing up. > > So if I stuff the asm macro in a global asm() block then GCC ends up > looking like so: > > .set warn_imm, 0 > warn_add_reg var=warn_imm reg=%rcx # tmp215 > .set warn_imm, (warn_imm << 4) > warn_add_reg var=warn_imm reg=%rdx # tmp212 > 1: ud1 warn_imm(%ecx),%rax # tmp210 > .pushsection .discard.annotate_insn,"M",@progbits,8 > .long 1b - . > .long 8 > .popsection > .pushsection __bug_table, "aw" ; 123: .long 1b - . ; .long .LC76 - . ; .long .LC0 - . ; .word 8710 ; .word 2321 ; .org 123b + 6 + 4 + 6 ; .popsection #,,, > > However, clangd is 'helpful' and fully expands the asm macro for the .s > file :-( It generates his horror show: #APP .set warn_imm, 0 .set .Lregnr, 0 .set .Lregnr, 1 .set .Lregnr, 2 .set warn_imm, 2 .set .Lregnr, 3 .set .Lregnr, 4 .set .Lregnr, 5 .set .Lregnr, 6 .set .Lregnr, 7 .set .Lregnr, 8 .set .Lregnr, 9 .set .Lregnr, 10 .set .Lregnr, 11 .set .Lregnr, 12 .set .Lregnr, 13 .set .Lregnr, 14 .set .Lregnr, 15 .set .Lregnr, 16 .set .Lregnr, 0 .set .Lregnr, 1 .set .Lregnr, 2 .set .Lregnr, 3 .set .Lregnr, 4 .set .Lregnr, 5 .set .Lregnr, 6 .set .Lregnr, 7 .set .Lregnr, 8 .set .Lregnr, 9 .set .Lregnr, 10 .set .Lregnr, 11 .set .Lregnr, 12 .set .Lregnr, 13 .set .Lregnr, 14 .set .Lregnr, 15 .set .Lregnr, 16 .set warn_imm, 32 .set .Lregnr, 0 .set .Lregnr, 1 .set warn_imm, 33 .set .Lregnr, 2 .set .Lregnr, 3 .set .Lregnr, 4 .set .Lregnr, 5 .set .Lregnr, 6 .set .Lregnr, 7 .set .Lregnr, 8 .set .Lregnr, 9 .set .Lregnr, 10 .set .Lregnr, 11 .set .Lregnr, 12 .set .Lregnr, 13 .set .Lregnr, 14 .set .Lregnr, 15 .set .Lregnr, 16 .set .Lregnr, 0 .set .Lregnr, 1 .set .Lregnr, 2 .set .Lregnr, 3 .set .Lregnr, 4 .set .Lregnr, 5 .set .Lregnr, 6 .set .Lregnr, 7 .set .Lregnr, 8 .set .Lregnr, 9 .set .Lregnr, 10 .set .Lregnr, 11 .set .Lregnr, 12 .set .Lregnr, 13 .set .Lregnr, 14 .set .Lregnr, 15 .set .Lregnr, 16 .Ltmp1656: ud1q 33(%ecx), %rax .section .discard.annotate_insn,"M",@progbits,8 .Ltmp1657: .long .Ltmp1656-.Ltmp1657 .long 8 .section .init.text,"ax",@progbits .section __bug_table,"aw",@progbits .Ltmp1658: .Ltmp1659: .long .Ltmp1656-.Ltmp1659 .Ltmp1660: .long .L.str.29-.Ltmp1660 .Ltmp1661: .long .L.str-.Ltmp1661 .short 8710 .short 2321 .org ((.Ltmp1658+6)+4)+6, 0 .section .init.text,"ax",@progbits #NO_APP