From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755045Ab1JKPrP (ORCPT ); Tue, 11 Oct 2011 11:47:15 -0400 Received: from smail3.alcatel.fr ([64.208.49.56]:52837 "EHLO smail3.alcatel.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754966Ab1JKPrO (ORCPT ); Tue, 11 Oct 2011 11:47:14 -0400 X-Greylist: delayed 642 seconds by postgrey-1.27 at vger.kernel.org; Tue, 11 Oct 2011 11:47:14 EDT Message-ID: <4E946279.8090800@alcatel-lucent.com> Date: Tue, 11 Oct 2011 17:36:25 +0200 From: Thanh-Lam NGUYEN User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:7.0.1) Gecko/20110929 Thunderbird/7.0.1 MIME-Version: 1.0 To: Alexander Viro CC: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Benjamin ZORES Subject: [PATCH] binfmt_elf.c: core file shrinking Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The vma_shrink function looks for the 1st allocated and the last allocated page. Only this part is dumped to the disk (the virual start address and the size are dupdated to reflect the new dumped information). Signed-off-by: Thanh Lam NGUYEN Signed-off-by: Benjamin ZORES --- linux/fs/binfmt_elf.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 55 insertions(+), 4 deletions(-) --- linux/fs/binfmt_elf.c +++ linux/fs/binfmt_elf.c @@ -1085,6 +1085,48 @@ * Jeremy Fitzhardinge */ +/* + * Search for 1st and last allocated page from vma_start to vma_end. + * Update vma_start and vma_end to reflect the result. + */ +void vma_shrink(struct vm_area_struct *vma, unsigned long *vma_start, + unsigned long *vma_end) +{ + int allocated; + unsigned long start, addr, end; + + allocated = 0; + start = end = *vma_start; + for (addr = *vma_start; _addr < *vma_end; addr += PAGE_SIZE) { + struct page *page; + if (get_user_pages(current, current->mm, addr, 1, 0, 1, + &page, NULL) <= 0) { + /* NO PAGE */ + if (!allocated) + start = addr; + } else { + if (page == ZERO_PAGE(0)) { + /* ZERO PAGE */ + if (!allocated) + start = addr; + } else { + /* ALLOCATED PAGE */ + if (!allocated) + start = addr; + end = addr; + allocated = 1; + } + page_cache_release(page); + } + } + if (end < start) + end = start; + if (allocated) + end += PAGE_SIZE; + *vma_start = start; + *vma_end = end; +} + /* * Decide what to dump of a segment, part, all or none. */ @@ -1980,13 +2022,19 @@ static int elf_core_dump(struct coredump_params *cprm) for (vma = first_vma(current, gate_vma); vma != NULL; vma = next_vma(vma, gate_vma)) { struct elf_phdr phdr; + unsigned long start = vma->vm_start; + unsigned long end = vma->vm_end; phdr.p_type = PT_LOAD; phdr.p_offset = offset; - phdr.p_vaddr = vma->vm_start; phdr.p_paddr = 0; phdr.p_filesz = vma_dump_size(vma, cprm->mm_flags); - phdr.p_memsz = vma->vm_end - vma->vm_start; + if (phdr.p_filesz) { + vma_shrink(vma, &start, &end); + phdr.p_filesz = end-start; + } + phdr.p_vaddr = start; + phdr.p_memsz = vma->vm_end - phdr.p_vaddr; offset += phdr.p_filesz; phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0; if (vma->vm_flags & VM_WRITE) @@ -2018,11 +2066,15 @@ static int elf_core_dump(struct coredump_params *cprm) for (vma = first_vma(current, gate_vma); vma != NULL; vma = next_vma(vma, gate_vma)) { unsigned long addr; + unsigned long start; unsigned long end; - end = vma->vm_start + vma_dump_size(vma, cprm->mm_flags); + start = vma->vm_start; + end = start + vma_dump_size(vma, cprm->mm_flags); + if (start < end) + vma_shrink(vma, &start, &end); - for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) { + for (addr = start; addr < end; addr += PAGE_SIZE) { struct page *page; int stop; --- =~=~=~=~=~=~=~=~=~=~=~=~==~=~=~=~=~=~=~=~=~=~=~=~=~=~= Thanh lam NGUYEN Prestataire externe ALTEN | ALTEN Subcontractor pour ALCATEL-LUCENT | in ALCATEL-LUCENT email: tlnguyen@webmail.alten.fr