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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B36CCD37BC for ; Sat, 16 Sep 2023 14:34:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238158AbjIPOeX (ORCPT ); Sat, 16 Sep 2023 10:34:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239442AbjIPOeW (ORCPT ); Sat, 16 Sep 2023 10:34:22 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99390CE8; Sat, 16 Sep 2023 07:34:16 -0700 (PDT) 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=uWg+CjZp6pxnNhsobBoEIP17WYA0CfxidefvFWg7MJo=; b=PR69pf8rgy43jUBW1riqJEYCOk 4xweYKKMSdTGyzPBNHWkB0Dpxag5wSUlLQ1cthhL9JNBAEd1rtjY4yyF4r3C8iFDaNwbB+6Cu1vJR VEa9ICsGyHuxU0x5CiykcBi8Y3dLHleMsGi4xdsmt3OjSeF53OJ0UrBROeKkgC6IOiksWgyUMt8Yf wmrg6OkDUjMRRTXxtMcFJPJ24ER05cck/OTMe1MK/yeU40SIgJFmDcDoDsDc6u/vC4C0qBs2fh5WH nqffeRog131qazSdbvo9E+SGOwTVMCIKVx01L7JIh0cTlJWx6QAf9HDAdXAI5nMd6dtui63/Lhwck PC+Az47A==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qhWN9-00Gf2K-7B; Sat, 16 Sep 2023 14:34:11 +0000 Date: Sat, 16 Sep 2023 15:34:11 +0100 From: Matthew Wilcox To: Greg Ungerer Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, Nicholas Piggin Subject: Re: [PATCH 09/17] m68k: Implement xor_unlock_is_negative_byte Message-ID: References: <20230915183707.2707298-1-willy@infradead.org> <20230915183707.2707298-10-willy@infradead.org> <6e409d5f-a419-07b7-c82c-4e80fe19c6ba@westnet.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6e409d5f-a419-07b7-c82c-4e80fe19c6ba@westnet.com.au> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Sep 16, 2023 at 11:11:32PM +1000, Greg Ungerer wrote: > On 16/9/23 04:36, Matthew Wilcox (Oracle) wrote: > > Using EOR to clear the guaranteed-to-be-set lock bit will test the > > negative flag just like the x86 implementation. This should be > > more efficient than the generic implementation in filemap.c. It > > would be better if m68k had __GCC_ASM_FLAG_OUTPUTS__. > > > > Signed-off-by: Matthew Wilcox (Oracle) > > --- > > arch/m68k/include/asm/bitops.h | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > > diff --git a/arch/m68k/include/asm/bitops.h b/arch/m68k/include/asm/bitops.h > > index e984af71df6b..909ebe7cab5d 100644 > > --- a/arch/m68k/include/asm/bitops.h > > +++ b/arch/m68k/include/asm/bitops.h > > @@ -319,6 +319,20 @@ arch___test_and_change_bit(unsigned long nr, volatile unsigned long *addr) > > return test_and_change_bit(nr, addr); > > } > > +static inline bool xor_unlock_is_negative_byte(unsigned long mask, > > + volatile unsigned long *p) > > +{ > > + char result; > > + char *cp = (char *)p + 3; /* m68k is big-endian */ > > + > > + __asm__ __volatile__ ("eor.b %1, %2; smi %0" > > The ColdFire members of the 68k family do not support byte size eor: > > CC mm/filemap.o > {standard input}: Assembler messages: > {standard input}:824: Error: invalid instruction for this architecture; needs 68000 or higher (68000 [68ec000, 68hc000, 68hc001, 68008, 68302, 68306, 68307, 68322, 68356], 68010, 68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060], cpu32 [68330, 68331, 68332, 68333, 68334, 68336, 68340, 68341, 68349, 68360], fidoa [fido]) -- statement `eor.b #1,3(%a0)' ignored Well, that sucks. What do you suggest for Coldfire? (Shame you didn't join in on the original discussion: https://lore.kernel.org/linux-m68k/ZLmKq2VLjYGBVhMI@casper.infradead.org/ )