From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752469AbdEPR6Z (ORCPT ); Tue, 16 May 2017 13:58:25 -0400 Received: from mail-pg0-f49.google.com ([74.125.83.49]:32863 "EHLO mail-pg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970AbdEPR6W (ORCPT ); Tue, 16 May 2017 13:58:22 -0400 Date: Tue, 16 May 2017 10:58:20 -0700 From: Matthias Kaehlcke To: Guenter Roeck Cc: David Howells , Sudip Mukherjee , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: frv build failure in mainline kernel Message-ID: <20170516175820.GC141096@google.com> References: <4ce754dc-36dc-972f-3685-f50d50cda02c@roeck-us.net> <20170515170215.GA30333@roeck-us.net> <20170515191342.GA141096@google.com> <15548.1494938660@warthog.procyon.org.uk> <18190.1494950672@warthog.procyon.org.uk> <20170516172130.GA32182@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170516172130.GA32182@roeck-us.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org El Tue, May 16, 2017 at 10:21:30AM -0700 Guenter Roeck ha dit: > On Tue, May 16, 2017 at 05:04:32PM +0100, David Howells wrote: > > Guenter Roeck wrote: > > > > > Turns out not here because ____cacheline_aligned_in_smp includes > > > __page_aligned_data which also declares the section, at least on x86. > > > > If there's any sort of section specification, that should suffice, I think. > > The problem might come that jiffies and jiffies_64 don't coincide at the same > > address because FRV is BE not LE. > > > > It ought to be possible to make jiffies 64-bit on FRV since it has double-word > > instructions that can load/store aligned 64-bit values atomically to/from a > > register pair. That might require some compiler magic, though. I'll have to > > try and work out if that's possible. > > > I tried: > > diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h > index 36872fbb815d..26d0655c4422 100644 > --- a/include/linux/jiffies.h > +++ b/include/linux/jiffies.h > @@ -64,13 +64,15 @@ extern int register_refined_jiffies(long clock_tick_rate); > /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ > #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) > > +#define __jiffy_data __attribute__((section(".data"))) > + > /* > * The 64-bit value is not atomic - you MUST NOT read it > * without sampling the sequence number in jiffies_lock. > * get_jiffies_64() will do this for you as appropriate. > */ > -extern u64 __cacheline_aligned_in_smp jiffies_64; > -extern unsigned long volatile __cacheline_aligned_in_smp jiffies; > +extern u64 __cacheline_aligned_in_smp __jiffy_data jiffies_64; > +extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_data jiffies; > > This is what I get when building defconfig: > > CC arch/x86/kernel/asm-offsets.s > In file included from ./include/linux/ktime.h:25:0, > from ./include/linux/rcupdate.h:46, > from ./include/linux/srcu.h:33, > from ./include/linux/notifier.h:15, > from ./include/linux/memory_hotplug.h:6, > from ./include/linux/mmzone.h:757, > from ./include/linux/gfp.h:5, > from ./include/linux/slab.h:14, > from ./include/linux/crypto.h:24, > from arch/x86/kernel/asm-offsets.c:8: > ./include/linux/jiffies.h:74:52: error: section of ‘jiffies_64’ conflicts with previous declaration > extern u64 __cacheline_aligned_in_smp __jiffy_data jiffies_64; > ^ > ./include/linux/jiffies.h:75:71: error: section of ‘jiffies’ conflicts with previous declaration > extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_data jiffies; > ^ > Kbuild:56: recipe for target 'arch/x86/kernel/asm-offsets.s' failed > make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1 > Makefile:1061: recipe for target 'prepare0' failed > make: *** [prepare0] Error 2 Thanks for giving it a try! What would work is this: diff --git a/arch/frv/include/asm/cache.h b/arch/frv/include/asm/cache.h index 2797163b8f4f..25bf4e85f582 100644 --- a/arch/frv/include/asm/cache.h +++ b/arch/frv/include/asm/cache.h @@ -20,4 +20,6 @@ #define __cacheline_aligned __attribute__((aligned(L1_CACHE_BYTES))) #define ____cacheline_aligned __attribute__((aligned(L1_CACHE_BYTES))) +#define __jiffies_arch_xyz __attribute__((__section__(".data"))) + #endif diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index 36872fbb815d..8904eb52928d 100644 --- a/include/linux/jiffies.h +++ b/include/linux/jiffies.h @@ -70,7 +70,7 @@ extern int register_refined_jiffies(long clock_tick_rate); * get_jiffies_64() will do this for you as appropriate. */ extern u64 __cacheline_aligned_in_smp jiffies_64; -extern unsigned long volatile __cacheline_aligned_in_smp jiffies; +extern unsigned long volatile __cacheline_aligned_in_smp __jiffies_arch_xyz jiffies; #if (BITS_PER_LONG < 64) u64 get_jiffies_64(void); We'd only have to find a halfway decent name for __jiffies_arch_xyz. Matthias