From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 476E0C35247 for ; Tue, 4 Feb 2020 17:59:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E9E02084E for ; Tue, 4 Feb 2020 17:59:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="m/jQpv2J" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727539AbgBDR73 (ORCPT ); Tue, 4 Feb 2020 12:59:29 -0500 Received: from mail-pj1-f67.google.com ([209.85.216.67]:33772 "EHLO mail-pj1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727512AbgBDR73 (ORCPT ); Tue, 4 Feb 2020 12:59:29 -0500 Received: by mail-pj1-f67.google.com with SMTP id m7so1060002pjs.0 for ; Tue, 04 Feb 2020 09:59:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=b/tatmAbPqQvnbldAouTM/R8vE/FozyyVbJhnSwJXGA=; b=m/jQpv2JIjMmYb0com4+E9ygLdFliyeNs30azzuB5uZxmGdg2Z6m6ZNxWcUsWuV/58 a/IYICceuBaOBCgC5vHB1M3Jd8ov0ZRQT07oApqu7FdsVSYpwcxaE7bmxkWzs1URLwwk OwaD4YOFmg4eX2KSoNfwnkbvyGlH4m9IfKZ/75I3RkdIbKGQOz8Vkr3RbNDIgyNugFeX 4ubvJkQ2YxE9geC4va10CzZfuDAe5NXvu5zbP1vIrNorrYvodKAKH04QZ5nPkGJ0v0A2 IZiSap0cjNjQ7ZwaeUo3lB1kD7GRcAn9Q7ywK3zOwnE5nNbWCy76F70T1AFe2UZ0qvIt cDrg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=b/tatmAbPqQvnbldAouTM/R8vE/FozyyVbJhnSwJXGA=; b=h99fc/NrscsrVI/2y2J+8I6rvgswszSY91nUC10ucKdE8pKVLg0hT5ZjWiZ97qoC4Z LeGX2NbrajDmF7aCDnuRavNcY6g9IkSrPYMhXvgx08chJFbXaA365nJmnqvKiMAoFCag UcCkTIPfxPo+eW7t51rOEltCQ5RsKVvFkbWhwZc3E7anbrhb8MUL0UlR6WkdI99CsPzJ ww7GL1UgF+2N2xXXDE1ucHUVOWSavBDaPOuHsZ0B8vkCvGRDFeVj9Cm3iQqbVogVbhyi idcPMQ5C/6YCk73J6+SH3MSNL7x6SNaXKSM+JLfBCwJTEdQodXGZTl3pCId63whbt3Ft 5bwQ== X-Gm-Message-State: APjAAAU6ZhPwA+sYJWNyz9NWohRdE9Qwl1WSOTJyIzrc0sL4XVnWDwcK adEE5Xp2TEXZAshi/GUE0vq+D4vv1FM= X-Google-Smtp-Source: APXvYqz/wsrLImmXNuI6MmUGKvGiwMhcKuUinmHKrZOCjZ8lY4eaVm8L+1GK00GJH3It8luUkRKQ+Q== X-Received: by 2002:a17:90b:4015:: with SMTP id ie21mr334038pjb.1.1580839168199; Tue, 04 Feb 2020 09:59:28 -0800 (PST) Received: from localhost.localdomain ([2620:0:1008:fd00:25a6:3140:768c:a64d]) by smtp.gmail.com with ESMTPSA id d73sm25414465pfd.109.2020.02.04.09.59.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Feb 2020 09:59:27 -0800 (PST) From: Andrei Vagin To: Vincenzo Frascino Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Andrei Vagin , Thomas Gleixner , Dmitry Safonov Subject: [PATCH 4/5] arm64/vdso: Handle faults on timens page Date: Tue, 4 Feb 2020 09:59:12 -0800 Message-Id: <20200204175913.74901-5-avagin@gmail.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20200204175913.74901-1-avagin@gmail.com> References: <20200204175913.74901-1-avagin@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a task belongs to a time namespace then the VVAR page which contains the system wide VDSO data is replaced with a namespace specific page which has the same layout as the VVAR page. Signed-off-by: Andrei Vagin --- arch/arm64/kernel/vdso.c | 55 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 51 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index bc93e26ae485..2e553468b183 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -171,15 +172,61 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) up_write(&mm->mmap_sem); return 0; } + +static struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + if (likely(vma->vm_mm == current->mm)) + return current->nsproxy->time_ns->vvar_page; + + /* + * VM_PFNMAP | VM_IO protect .fault() handler from being called + * through interfaces like /proc/$pid/mem or + * process_vm_{readv,writev}() as long as there's no .access() + * in special_mapping_vmops(). + * For more details check_vma_flags() and __access_remote_vm() + */ + + WARN(1, "vvar_page accessed remotely"); + + return NULL; +} +#else +static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + return NULL; +} #endif static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf) { - if (vmf->pgoff == 0) - return vmf_insert_pfn(vma, vmf->address, - sym_to_pfn(vdso_data)); - return VM_FAULT_SIGBUS; + struct page *timens_page = find_timens_vvar_page(vma); + unsigned long pfn; + + switch (vmf->pgoff) { + case VVAR_DATA_PAGE_OFFSET: + if (timens_page) + pfn = page_to_pfn(timens_page); + else + pfn = sym_to_pfn(vdso_data); + break; + case VVAR_TIMENS_PAGE_OFFSET: + /* + * If a task belongs to a time namespace then a namespace + * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and + * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET + * offset. + * See also the comment near timens_setup_vdso_data(). + */ + if (!timens_page) + return VM_FAULT_SIGBUS; + pfn = sym_to_pfn(vdso_data); + break; + default: + return VM_FAULT_SIGBUS; + } + + return vmf_insert_pfn(vma, vmf->address, pfn); } static int __setup_additional_pages(enum arch_vdso_type arch_index, -- 2.24.1