From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7164C4727E for ; Thu, 1 Oct 2020 20:48:37 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6EC9D20738 for ; Thu, 1 Oct 2020 20:48:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EC9D20738 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4C2QFY4lx7zDqdD for ; Fri, 2 Oct 2020 06:48:33 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=permerror (SPF Permanent Error: Unknown mechanism found: ip:192.40.192.88/32) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4C2QCR1m2VzDqbk for ; Fri, 2 Oct 2020 06:46:42 +1000 (AEST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 091KiIqu017242; Thu, 1 Oct 2020 15:44:19 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 091KiHHX017241; Thu, 1 Oct 2020 15:44:17 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Thu, 1 Oct 2020 15:44:17 -0500 From: Segher Boessenkool To: Christophe Leroy Subject: Re: [PATCH 1/6] powerpc/time: Rename mftbl() to mftb() Message-ID: <20201001204417.GP28786@gate.crashing.org> References: <94dc68d3d9ef9eb549796d4b938b6ba0305a049b.1601556145.git.christophe.leroy@csgroup.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94dc68d3d9ef9eb549796d4b938b6ba0305a049b.1601556145.git.christophe.leroy@csgroup.eu> User-Agent: Mutt/1.4.2.3i X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Oct 01, 2020 at 12:42:39PM +0000, Christophe Leroy wrote: > On PPC64, we have mftb(). > On PPC32, we have mftbl() and an #define mftb() mftbl(). > > mftb() and mftbl() are equivalent, their purpose is to read the > content of SPRN_TRBL, as returned by 'mftb' simplified instruction. > > binutils seems to define 'mftbl' instruction as an equivalent > of 'mftb'. > > However in both 32 bits and 64 bits documentation, only 'mftb' is > defined, and when performing a disassembly with objdump, the displayed > instruction is 'mftb' > > No need to have two ways to do the same thing with different > names, rename mftbl() to have only mftb(). There are mttbl and mttbu insns (and no mttb insn); they write a 32-bit half for the time base. There is an mftb, and an mftbu. mftbu reads the upper half, while mftb reads the *whole* register. SPR 269 is the TBU register, while SPR 268 is called both TB and TBL. Yes, it is confusing :-) The "mftb" name is much clearer than "mftbl" (on 64-bit), because it reads the whole 64-bit register. On 32-bit mftbl is clearer (but not defined in the architecture, not officially an insn or even an extended mnemonic). Segher