From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Uc4VI-0002kI-SZ for kexec@lists.infradead.org; Tue, 14 May 2013 01:58:14 +0000 Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 973A73EE0C3 for ; Tue, 14 May 2013 10:57:53 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 8749F45DE52 for ; Tue, 14 May 2013 10:57:53 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 649D145DDCF for ; Tue, 14 May 2013 10:57:53 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 3E0E8E08002 for ; Tue, 14 May 2013 10:57:53 +0900 (JST) Received: from m1000.s.css.fujitsu.com (m1000.s.css.fujitsu.com [10.240.81.136]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id DADBAE08004 for ; Tue, 14 May 2013 10:57:52 +0900 (JST) From: HATAYAMA Daisuke Subject: [PATCH v5 8/8] vmcore: support mmap() on /proc/vmcore Date: Tue, 14 May 2013 10:57:52 +0900 Message-ID: <20130514015752.18697.80784.stgit@localhost6.localdomain6> In-Reply-To: <20130514015622.18697.77191.stgit@localhost6.localdomain6> References: <20130514015622.18697.77191.stgit@localhost6.localdomain6> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: vgoyal@redhat.com, ebiederm@xmission.com, akpm@linux-foundation.org Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, lisa.mitchell@hp.com, linux-mm@kvack.org, zhangyanfei@cn.fujitsu.com, kumagai-atsushi@mxc.nes.nec.co.jp, cpw@sgi.com, jingbai.ma@hp.com This patch introduces mmap_vmcore(). Don't permit writable nor executable mapping even with mprotect() because this mmap() is aimed at reading crash dump memory. Non-writable mapping is also requirement of remap_pfn_range() when mapping linear pages on non-consecutive physical pages; see is_cow_mapping(). Set VM_MIXEDMAP flag to remap memory by remap_pfn_range and by remap_vmalloc_range_pertial at the same time for a single vma. do_munmap() can correctly clean partially remapped vma with two functions in abnormal case. See zap_pte_range(), vm_normal_page() and their comments for details. On x86-32 PAE kernels, mmap() supports at most 16TB memory only. This limitation comes from the fact that the third argument of remap_pfn_range(), pfn, is of 32-bit length on x86-32: unsigned long. Signed-off-by: HATAYAMA Daisuke --- fs/proc/vmcore.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 86 insertions(+), 0 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index ad6da17..d4b88f6 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include "internal.h" @@ -200,9 +201,94 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer, return acc; } +static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) +{ + size_t size = vma->vm_end - vma->vm_start; + u64 start, end, len, tsz; + struct vmcore *m; + + start = (u64)vma->vm_pgoff << PAGE_SHIFT; + end = start + size; + + if (size > vmcore_size || end > vmcore_size) + return -EINVAL; + + if (vma->vm_flags & (VM_WRITE | VM_EXEC)) + return -EPERM; + + vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC); + vma->vm_flags |= VM_MIXEDMAP; + + len = 0; + + if (start < elfcorebuf_sz) { + u64 pfn; + + tsz = elfcorebuf_sz - start; + if (size < tsz) + tsz = size; + pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT; + if (remap_pfn_range(vma, vma->vm_start, pfn, tsz, + vma->vm_page_prot)) + return -EAGAIN; + size -= tsz; + start += tsz; + len += tsz; + + if (size == 0) + return 0; + } + + if (start < elfcorebuf_sz + elfnotesegbuf_sz) { + void *kaddr; + + tsz = elfcorebuf_sz + elfnotesegbuf_sz - start; + if (size < tsz) + tsz = size; + kaddr = elfnotesegbuf + start - elfcorebuf_sz; + if (remap_vmalloc_range_partial(vma, vma->vm_start + len, + kaddr, tsz)) { + do_munmap(vma->vm_mm, vma->vm_start, len); + return -EAGAIN; + } + size -= tsz; + start += tsz; + len += tsz; + + if (size == 0) + return 0; + } + + list_for_each_entry(m, &vmcore_list, list) { + if (start < m->offset + m->size) { + u64 paddr = 0; + + tsz = m->offset + m->size - start; + if (size < tsz) + tsz = size; + paddr = m->paddr + start - m->offset; + if (remap_pfn_range(vma, vma->vm_start + len, + paddr >> PAGE_SHIFT, tsz, + vma->vm_page_prot)) { + do_munmap(vma->vm_mm, vma->vm_start, len); + return -EAGAIN; + } + size -= tsz; + start += tsz; + len += tsz; + + if (size == 0) + return 0; + } + } + + return 0; +} + static const struct file_operations proc_vmcore_operations = { .read = read_vmcore, .llseek = default_llseek, + .mmap = mmap_vmcore, }; static struct vmcore* __init get_new_element(void) _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec