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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 CCBDDC3A5A9 for ; Mon, 4 May 2020 05:44:51 +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 7E1E120721 for ; Mon, 4 May 2020 05:44:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E1E120721 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=popple.id.au 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 49FsJ13X38zDqlJ for ; Mon, 4 May 2020 15:44:49 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 49FsCs1SnJzDqT2 for ; Mon, 4 May 2020 15:41:13 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=popple.id.au Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 49FsCr5wmwz9sSw; Mon, 4 May 2020 15:41:12 +1000 (AEST) From: Alistair Popple To: Jordan Niethe Subject: Re: [PATCH v7 04/28] powerpc/xmon: Use bitwise calculations in_breakpoint_table() Date: Mon, 04 May 2020 15:41:12 +1000 Message-ID: <8567555.I5S1BN7I14@townsend> In-Reply-To: <20200501034220.8982-5-jniethe5@gmail.com> References: <20200501034220.8982-1-jniethe5@gmail.com> <20200501034220.8982-5-jniethe5@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" 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: npiggin@gmail.com, bala24@linux.ibm.com, naveen.n.rao@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, dja@axtens.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" I probably would have just folded this change into patch 2 but it looks fine to me. Reviewed-by: Alistair Popple On Friday, 1 May 2020 1:41:56 PM AEST Jordan Niethe wrote: > A modulo operation is used for calculating the current offset from a > breakpoint within the breakpoint table. As instruction lengths are > always a power of 2, this can be replaced with a bitwise 'and'. The > current check for word alignment can be replaced with checking that the > lower 2 bits are not set. > > Suggested-by: Christophe Leroy > Signed-off-by: Jordan Niethe > --- > v6: New to series > --- > arch/powerpc/xmon/xmon.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c > index bbfea22f4a96..e122f0c8a044 100644 > --- a/arch/powerpc/xmon/xmon.c > +++ b/arch/powerpc/xmon/xmon.c > @@ -857,8 +857,8 @@ static struct bpt *in_breakpoint_table(unsigned long > nip, unsigned long *offp) off = nip - (unsigned long) bpt_table; > if (off >= sizeof(bpt_table)) > return NULL; > - *offp = off % BPT_SIZE; > - if (*offp != 0 && *offp != 4) > + *offp = off & (BPT_SIZE - 1); > + if (off & 3) > return NULL; > return bpts + (off / BPT_SIZE); > }