Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760198Ab3D2Twg (ORCPT ); Mon, 29 Apr 2013 15:52:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44972 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759596Ab3D2Twe (ORCPT ); Mon, 29 Apr 2013 15:52:34 -0400 Date: Mon, 29 Apr 2013 15:51:54 -0400 From: Vivek Goyal To: HATAYAMA Daisuke Cc: ebiederm@xmission.com, akpm@linux-foundation.org, cpw@sgi.com, kumagai-atsushi@mxc.nes.nec.co.jp, lisa.mitchell@hp.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, zhangyanfei@cn.fujitsu.com, jingbai.ma@hp.com Subject: Re: [PATCH v4 7/8] vmcore: treat memory chunks referenced by PT_LOAD program header entries in page-size boundary in vmcore_list Message-ID: <20130429195154.GR8204@redhat.com> References: <20130413002000.18245.21513.stgit@localhost6.localdomain6> <20130413002145.18245.73180.stgit@localhost6.localdomain6> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130413002145.18245.73180.stgit@localhost6.localdomain6> 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 Content-Length: 2521 Lines: 67 On Sat, Apr 13, 2013 at 09:21:46AM +0900, HATAYAMA Daisuke wrote: > Treat memory chunks referenced by PT_LOAD program header entries in > page-size boundary in vmcore_list. Formally, for each range [start, > end], we set up the corresponding vmcore object in vmcore_list to > [rounddown(start, PAGE_SIZE), roundup(end, PAGE_SIZE)]. > > This change affects layout of /proc/vmcore. The gaps generated by the > rearrangement are newly made visible to applications as > holes. Concretely, they are two ranges [rounddown(start, PAGE_SIZE), > start] and [end, roundup(end, PAGE_SIZE)]. Sorry did not understand this part. So if end is not page aligned, then we roundup(end, PAGE_SIZE) and increase the PT_LOAD size accordingly? Similarly for start, we do roundown(). - Can you really rounddown() start? Then you will have to change start virtual address in program header and that's not really a good idea. - So this extra memory for end, we read from old memory and not fill with zeros? > > Signed-off-by: HATAYAMA Daisuke > --- > > fs/proc/vmcore.c | 26 ++++++++++++++++++++------ > 1 files changed, 20 insertions(+), 6 deletions(-) > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > index 029bdc0..cd0f9d9 100644 > --- a/fs/proc/vmcore.c > +++ b/fs/proc/vmcore.c > @@ -477,16 +477,23 @@ static int __init process_ptload_program_headers_elf64(char *elfptr, > vmcore_off = elfsz + roundup(phdr_ptr->p_memsz, PAGE_SIZE); > > for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { > + u64 paddr, start, end, size; > + > if (phdr_ptr->p_type != PT_LOAD) > continue; > > + paddr = phdr_ptr->p_offset; > + start = rounddown(paddr, PAGE_SIZE); > + end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE); > + size = end - start; > + > /* Add this contiguous chunk of memory to vmcore list.*/ > - if (vmcore_add(vc_list, phdr_ptr->p_offset, phdr_ptr->p_memsz)) > + if (vmcore_add(vc_list, start, size)) > return -ENOMEM; > > /* Update the program header offset. */ > - phdr_ptr->p_offset = vmcore_off; > - vmcore_off = vmcore_off + phdr_ptr->p_memsz; > + phdr_ptr->p_offset = vmcore_off + (paddr - start); What's paddr-start. Why following is not sufficient. phdr_ptr->p_offset = vmcore_off Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/