Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755167AbcDGD4R (ORCPT ); Wed, 6 Apr 2016 23:56:17 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:35422 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755058AbcDGD4O (ORCPT ); Wed, 6 Apr 2016 23:56:14 -0400 Subject: Re: [PATCH v2 08/30] Add sparc-specific parity functions To: Sam Ravnborg , zengzhaoxiu@163.com References: <57031D9D.801@gmail.com> <1459933647-6940-1-git-send-email-zengzhaoxiu@163.com> <20160406184447.GA5963@ravnborg.org> Cc: davem@davemloft.net, wim.coekaerts@oracle.com, linux@roeck-us.net, julian.calaby@gmail.com, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org From: Zeng Zhaoxiu Message-ID: <5705DA58.3040207@gmail.com> Date: Thu, 7 Apr 2016 11:56:08 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160406184447.GA5963@ravnborg.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2002 Lines: 76 在 2016年04月07日 02:44, Sam Ravnborg 写道: > Hi Zeng. > >> Use runtime patching for sparc64, lifted from hweight > No errors found in patch - but a few comments. > In general patch looks good. Thanks. Sparc, powerpc, and x86 are all new to me. >> +++ b/arch/sparc/include/asm/bitops_64.h >> @@ -47,6 +47,24 @@ unsigned int __arch_hweight16(unsigned int w); >> unsigned int __arch_hweight8(unsigned int w); >> >> #include >> + >> +/* >> + * parityN: returns the parity of a N-bit word, >> + * i.e. the number of 1-bits in w modulo 2. >> + */ >> + >> +static inline unsigned int __arch_parity4(unsigned int w) >> +{ >> + w &= 0xf; >> + return (0x6996 >> w) & 1; >> +} > As Josef already said - this constant should have a name. > PARITY_BIT > ? > Maybe PARITY_MAGIC? >> +++ b/arch/sparc/kernel/sparc_ksyms_64.c >> @@ -45,6 +45,12 @@ EXPORT_SYMBOL(__arch_hweight16); >> EXPORT_SYMBOL(__arch_hweight32); >> EXPORT_SYMBOL(__arch_hweight64); >> >> +/* from parity.S */ >> +EXPORT_SYMBOL(__arch_parity8); >> +EXPORT_SYMBOL(__arch_parity16); >> +EXPORT_SYMBOL(__arch_parity32); >> +EXPORT_SYMBOL(__arch_parity64); > Did you compile this? > I wonder if bitops_64.h is indirectly included. Yes. >> index 0000000..b1945e3 >> --- /dev/null >> +++ b/arch/sparc/lib/parity.S >> @@ -0,0 +1,93 @@ >> +#include >> + >> + .text >> + .align 32 >> + >> +ENTRY(__arch_parity8) >> + srl %o0, 4, %g1 >> + xor %o0, %g1, %o0 >> + and %o0, 0xf, %o0 >> + sethi %hi(0x6996), %g1 >> + or %g1, %lo(0x6996), %g1 >> + srl %g1, %o0, %o0 >> + retl >> + and %o0, 1, %o0 >> +ENDPROC(__arch_parity8) > I know the level of comments in hweight is equal to none. > But please do not follow this bad example. > At least for each function a one-liner of the C code. > And in the top of the file maybe two lines that the functions > are patched at run-time if the processor has popc available. > > > Sam OK. I will try, but my english is very poor! :-)