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 B83495CDF1 for ; Tue, 17 Mar 2026 20:35:06 +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=1773779710; cv=none; b=vD6vLDutSUsucgK185eYlAmcumbXf4xrzqEJ7Nr49WA+1/cJsJ3yvIMCnefxH6p9oX6IEKtds4D2wrnFt97MYnz8XXXO3/KmtcaklA7KCAzWF0KCyE9BdAbrsB8Uu+PoVGiZw9O85s5cFOBuEzfrlTx5G5aoxLbMIUQ9G+2yHDg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773779710; c=relaxed/simple; bh=7/Lh3Iv3Z1koqzE6ogKwCW8/Gkk3RW6lAA+UTzWK8Fg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PyxGeBgf+BgnLn4HhuIvmuHBlxV1lN7utxzh5SbhYOne/KiJiG5Y9s0tldUFzntlPPOiYvscHWTJsdVM95cg9gTeRGer0AIzjTX1x8+t1i/dFmLDF1TdYNmcTI1cfJL2LggsIw+z9zdw/2Ot3xqKUeNOjEtXZ2DHRiovgK8WV6w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (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=LzBCPeir; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (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="LzBCPeir" 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=i8HXbN/G24ilxQ8SA7HYxWV7pxfpcCT8oOrg9IwjsoQ=; b=LzBCPeirwNfh3wnhKeKu6WVL8k gVkZU1UiBETfQXHj+alhsOq4Nxk/rSWE83CaBnIfhhFnT39BXguo/GWgbfO8hXi1oLcYbM+YlctEr hsDFoJ2+B2MyHYFdOMwirWasWhGgrlnWHna0wNNoRDq4u1maHteRuq9/6PLaAgKd2iXS5X0IsdE9t UUU8PvII5xoOusHimgU5RtKpICbknFLugGU5XjRbdwzKSFO+9EoJNrqDpyks4PGXBrFpj2szjtJeJ 1U/Ig5vf4ZQp8hA24OVutzXsfF1jJ44P0T0NjtpIgJRA8jJj7nm37K9vCXeaXS01FC2qXKP5fZLYq zb+85mCw==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1w2b84-00000003Htu-1zxn; Tue, 17 Mar 2026 20:35:04 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 869BF301BD5; Tue, 17 Mar 2026 21:35:02 +0100 (CET) Date: Tue, 17 Mar 2026 21:35:02 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann Subject: Re: [PATCH] objtool: Support Clang RAX DRAP sequence Message-ID: <20260317203502.GI2872@noisy.programming.kicks-ass.net> References: <3f33dc720b83dc6d3a2b7094f75a5c90a0b1cbc5.1773708458.git.jpoimboe@kernel.org> <20260317081825.GC3738010@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: On Tue, Mar 17, 2026 at 08:30:59AM -0700, Josh Poimboeuf wrote: > On Tue, Mar 17, 2026 at 09:18:25AM +0100, Peter Zijlstra wrote: > > On Mon, Mar 16, 2026 at 05:47:56PM -0700, Josh Poimboeuf wrote: > > > Recent Clang can use RAX as a temporary register for the DRAP stack > > > alignment sequence. Add support for that. > > > > > > Fixes the following warning: > > > > > > vmlinux.o: error: objtool: vmw_host_printf+0xd: unknown CFA base reg 0 > > > > > > Reported-by: Arnd Bergmann > > > Closes: https://lore.kernel.org/cefefdd1-7b82-406d-8ff4-e4b167e45ee6@app.fastmail.com > > > Signed-off-by: Josh Poimboeuf > > > --- > > > arch/x86/include/asm/orc_types.h | 1 + > > > arch/x86/kernel/unwind_orc.c | 8 ++++++++ > > > tools/arch/x86/include/asm/orc_types.h | 1 + > > > tools/objtool/arch/x86/decode.c | 3 +++ > > > tools/objtool/arch/x86/orc.c | 5 +++++ > > > 5 files changed, 18 insertions(+) > > > > > > diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h > > > index e0125afa53fb..b3cc7970fa54 100644 > > > --- a/arch/x86/include/asm/orc_types.h > > > +++ b/arch/x86/include/asm/orc_types.h > > > @@ -37,6 +37,7 @@ > > > #define ORC_REG_R13 7 > > > #define ORC_REG_BP_INDIRECT 8 > > > #define ORC_REG_SP_INDIRECT 9 > > > +#define ORC_REG_AX 10 > > > #define ORC_REG_MAX 15 > > > > I'm 'annoyed' at the placement of that register. I know its not > > important, but I can't silence my OCD saying that AX should come before > > DX. > > > > Also, SP comes before BP and both before DI. > > > > Something like so perhaps? > > That bothered me too, but I was trying to keep the diffstat down. But > sure, why not... > > What about the switch statements? Should we reorder them too while at > it? If so, starting to feel like a separate patch. Agreed, switch statement order should match the definition order. And yes separate patch is fine.