From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752827AbeC0PKe (ORCPT ); Tue, 27 Mar 2018 11:10:34 -0400 Received: from mga05.intel.com ([192.55.52.43]:22290 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752342AbeC0PKa (ORCPT ); Tue, 27 Mar 2018 11:10:30 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,367,1517904000"; d="scan'208";a="215114295" Message-ID: <1522163426.21176.24.camel@linux.intel.com> Subject: Re: [tip:x86/urgent] x86/io: Define readq()/writeq() to use 64-bit type From: Andy Shevchenko To: hpa@zytor.com, peterz@infradead.org, tglx@linutronix.de, mingo@kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, lkp@intel.com, sohil.mehta@intel.com, mitake@dcl.info.waseda.ac.jp, linux-tip-commits@vger.kernel.org Date: Tue, 27 Mar 2018 18:10:26 +0300 In-Reply-To: References: <20180119143322.16555-1-andriy.shevchenko@linux.intel.com> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.5-1+b1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2018-02-13 at 08:58 -0800, tip-bot for Andy Shevchenko wrote: > Commit-ID: 0fc8483b698620ea3d8cc6635b54eccc613c23a3 > Gitweb: https://git.kernel.org/tip/0fc8483b698620ea3d8cc6635b54ecc > c613c23a3 > Author: Andy Shevchenko > AuthorDate: Fri, 19 Jan 2018 16:33:22 +0200 > Committer: Ingo Molnar > CommitDate: Tue, 13 Feb 2018 17:14:41 +0100 As of today I don't see this in linux-next % git tag --contains 0fc8483b69862 next-20180214 next-20180215 next-20180216 What happened to this change? > > x86/io: Define readq()/writeq() to use 64-bit type > > Since non atomic readq() and writeq() were added some of the drivers > would like to use it in a manner of: > > #include > ... > pr_debug("Debug value of some register: %016llx\n", readq(addr)); > > However, lo_hi_readq() always returns __u64 data, while readq() > on x86_64 defines it as unsigned long. and thus compiler warns > about type mismatch, although they are both 64-bit on x86_64. > > Convert readq() and writeq() on x86 to operate on deterministic > 64-bit type. The most of architectures in the kernel already are using > either unsigned long long, or u64 type for readq() / writeq(). > This change propagates consistency in that sense. > > While this is not an issue per se, though if someone wants to address > it, > the anchor could be the commit > > 797a796a13df ("asm-generic: architecture independent readq/writeq > for 32bit environment") > > where non-atomic variants had been introduced. > > Note, there are only few users of above pattern and they will not be > affected because they do cast returned value. The actual warning has > been issued on not-yet-upstreamed code. > > Potentially we might get a new warnings if some 64-bit only code > assigns returned value to unsigned long type of variable. This is > assumed to be addressed on case-by-case basis. > > Reported-by: lkp > Tested-by: Sohil Mehta > Signed-off-by: Andy Shevchenko > Cc: Hitoshi Mitake > Cc: Linus Torvalds > Cc: Mehta, Sohil > Cc: Peter Zijlstra > Cc: Thomas Gleixner > Link: http://lkml.kernel.org/r/20180119143322.16555-1-andriy.shevchenk > o@linux.intel.com > Signed-off-by: Ingo Molnar > --- > arch/x86/include/asm/io.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h > index 95e9486..365f5ba 100644 > --- a/arch/x86/include/asm/io.h > +++ b/arch/x86/include/asm/io.h > @@ -94,10 +94,10 @@ build_mmio_write(__writel, "l", unsigned int, "r", > ) > > #ifdef CONFIG_X86_64 > > -build_mmio_read(readq, "q", unsigned long, "=r", :"memory") > -build_mmio_read(__readq, "q", unsigned long, "=r", ) > -build_mmio_write(writeq, "q", unsigned long, "r", :"memory") > -build_mmio_write(__writeq, "q", unsigned long, "r", ) > +build_mmio_read(readq, "q", unsigned long long, "=r", :"memory") > +build_mmio_read(__readq, "q", unsigned long long, "=r", ) > +build_mmio_write(writeq, "q", unsigned long long, "r", :"memory") > +build_mmio_write(__writeq, "q", unsigned long long, "r", ) > > #define readq_relaxed(a) __readq(a) > #define writeq_relaxed(v, a) __writeq(v, a) -- Andy Shevchenko Intel Finland Oy