From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lance Richardson Subject: Re: Sparse warnings on GENMASK + arm32 Date: Wed, 26 Jul 2017 09:33:01 -0400 (EDT) Message-ID: <1000702648.38599568.1501075981880.JavaMail.zimbra@redhat.com> References: <20170726013020.GL2146@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50156 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750783AbdGZNdC (ORCPT ); Wed, 26 Jul 2017 09:33:02 -0400 In-Reply-To: <20170726013020.GL2146@codeaurora.org> Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Stephen Boyd Cc: linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org > From: "Stephen Boyd" > To: linux-sparse@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Sent: Tuesday, 25 July, 2017 9:30:20 PM > Subject: Sparse warnings on GENMASK + arm32 > > I see sparse warning when I check a clk driver file in the kernel > on a 32-bit ARM build. > > drivers/clk/sunxi/clk-sun6i-ar100.c:65:20: warning: cast truncates bits from > constant value (3ffffffff becomes ffffffff) > > The code in question looks like: > > static const struct factors_data sun6i_ar100_data = { > .mux = 16, > .muxmask = GENMASK(1, 0), > .table = &sun6i_ar100_config, > .getter = sun6i_get_ar100_factors, > }; > > where factors_data is > > struct factors_data { > int enable; > int mux; > int muxmask; > const struct clk_factors_config *table; > void (*getter)(struct factors_request *req); > void (*recalc)(struct factors_request *req); > const char *name; > }; > > > and sparse seems to be complaining about the muxmask assignment > here. Oddly, this doesn't happen on arm64 builds. Both times, I'm > checking this on an x86-64 machine. > > $ sparse --version > v0.5.1-rc4-1-gfa71b7ac0594 > > Is there something confusing to sparse in the GENMASK macro? > Hmm, it seems sparse is incorrectly taking ~0UL to be a 64-bit value while BITS_PER_LONG is (correctly) evaluated to be 32. #define GENMASK(h, l) \ (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h)))) > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > a Linux Foundation Collaborative Project > -- > To unsubscribe from this list: send the line "unsubscribe linux-sparse" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >