From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932313Ab3JIRbz (ORCPT ); Wed, 9 Oct 2013 13:31:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52809 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932272Ab3JIRbv (ORCPT ); Wed, 9 Oct 2013 13:31:51 -0400 Message-ID: <1381339905.8305.31.camel@deneb.redhat.com> Subject: Re: [PATCH] arm64: add PAGE_ALIGNED_DATA to linker script From: Mark Salter To: Will Deacon Cc: "linux-kernel@vger.kernel.org" , Catalin Marinas Date: Wed, 09 Oct 2013 13:31:45 -0400 In-Reply-To: <20131009101447.GC5985@mudshark.cambridge.arm.com> References: <1381264659-11132-1-git-send-email-msalter@redhat.com> <20131009101447.GC5985@mudshark.cambridge.arm.com> Organization: Red Hat, Inc Content-Type: text/plain; charset="UTF-8" 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 Wed, 2013-10-09 at 11:14 +0100, Will Deacon wrote: > On Tue, Oct 08, 2013 at 09:37:39PM +0100, Mark Salter wrote: > > The arm64 linker script doesn't use the PAGE_ALIGNED_DATA macro which > > leads to a ".data..page_aligned" section being placed between the end > > of .data and start of .bss: > > > > % readelf -e vmlinux > > ... > > Section to Segment mapping: > > Segment Sections... > > 00 .head.text .text .text.init .rodata __ksymtab __ksymtab_gpl \ > > __ksymtab_strings __param __modver __ex_table .notes \ > > .init.text .init.data .data..percpu .data .data..page_aligned .bss > > > > This causes problems for the EFI stub which may have to relocate the > > kernel image based on stext and _edata symbols. > > > > This patch adds PAGE_ALIGNED_DATA() to the linker script inside the > > the .data section. > > > > Signed-off-by: Mark Salter > > --- > > arch/arm64/kernel/vmlinux.lds.S | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > > index f8ab9d8..e441556 100644 > > --- a/arch/arm64/kernel/vmlinux.lds.S > > +++ b/arch/arm64/kernel/vmlinux.lds.S > > @@ -110,6 +110,7 @@ SECTIONS > > */ > > INIT_TASK_DATA(THREAD_SIZE) > > NOSAVE_DATA > > + PAGE_ALIGNED_DATA(PAGE_SIZE) > > CACHELINE_ALIGNED_DATA(64) > > READ_MOSTLY_DATA(64) > > Can we just replace this chunk with RW_DATA_SECTION(64, PAGE_SIZE, > THREAD_SIZE) instead? Possibly. The layout of the included macros is the same. The only difference being the placement of _data, _sdata, and _edata inside .data and the use of __data_loc. --Mark