From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751707AbeEBOTl (ORCPT ); Wed, 2 May 2018 10:19:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:59396 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751641AbeEBOTd (ORCPT ); Wed, 2 May 2018 10:19:33 -0400 Date: Wed, 2 May 2018 10:19:30 -0400 From: Steven Rostedt To: changbin.du@intel.com Cc: yamada.masahiro@socionext.com, michal.lkml@markovi.net, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, rdunlap@infradead.org, x86@kernel.org, lgirdwood@gmail.com, broonie@kernel.org, arnd@arndb.de, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v2 5/5] asm-generic: fix build error in fix_to_virt with CONFIG_DEBUG_EXPERIENCE Message-ID: <20180502101930.25a5437d@gandalf.local.home> In-Reply-To: <1525268700-10631-6-git-send-email-changbin.du@intel.com> References: <1525268700-10631-1-git-send-email-changbin.du@intel.com> <1525268700-10631-6-git-send-email-changbin.du@intel.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2 May 2018 21:45:00 +0800 changbin.du@intel.com wrote: > From: Changbin Du > > With '-Og' optimization level, GCC would not optimize a count for a loop > as a constant value. But BUILD_BUG_ON() only accept compile-time constant > values. > > arch/arm/mm/mmu.o: In function `fix_to_virt': > /home/changbin/work/linux/./include/asm-generic/fixmap.h:31: undefined reference to `__compiletime_assert_31' > Makefile:1051: recipe for target 'vmlinux' failed > make: *** [vmlinux] Error 1 > > Signed-off-by: Changbin Du > --- > include/asm-generic/fixmap.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/include/asm-generic/fixmap.h b/include/asm-generic/fixmap.h > index 827e4d3..a6576d4 100644 > --- a/include/asm-generic/fixmap.h > +++ b/include/asm-generic/fixmap.h > @@ -28,7 +28,8 @@ > */ > static __always_inline unsigned long fix_to_virt(const unsigned int idx) > { > - BUILD_BUG_ON(idx >= __end_of_fixed_addresses); > + BUILD_BUG_ON(__builtin_constant_p(idx) && > + idx >= __end_of_fixed_addresses); Hmm, this changes the check slightly. Perhaps we should only do this when your config is active: { BUILD_BUG_ON( /* CONFIG_DEBUG_OPTIMIZE may cause idx not to be constant */ #ifdef CONFIG_DEBUG_OPTIMIZE __builtin_constant_p(idx) && #endif idx >= __end_of_fixed_addresses); } -- Steve > return __fix_to_virt(idx); > } >