From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.9 required=5.0 tests=DKIM_SIGNED, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id EFF1A7D043 for ; Thu, 7 Jun 2018 18:39:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934639AbeFGSj2 (ORCPT ); Thu, 7 Jun 2018 14:39:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:35510 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933893AbeFGSj1 (ORCPT ); Thu, 7 Jun 2018 14:39:27 -0400 Received: from mail-wm0-f50.google.com (mail-wm0-f50.google.com [74.125.82.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6557E2089C for ; Thu, 7 Jun 2018 18:39:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1528396766; bh=6LEe5GSpD2TEtbiZj63Ls647kqPk+eeU1iAj9CzQjbY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=b7UAeK2K9xzAJFf4bhIXufPou9uTWnE2h4VgA45mCGWrRscseNKP7AteoOwPek9UF 7Gi0NpV6RRkTm9Qtj6R+qoGNo7iCoerA2e0MYN0DtotT4gWK+sw8LofkocZQr/y2k2 K5iEyId7q1seMJSmsJ7TQ/ZguxtoS8Qv0wAkGAC0= Received: by mail-wm0-f50.google.com with SMTP id 69-v6so8052230wmf.3 for ; Thu, 07 Jun 2018 11:39:26 -0700 (PDT) X-Gm-Message-State: APt69E3vvkTOtzWc6MhvvYx4nYh6IbxbRys688ntagJILlQSneTbGie1 bWPZFSZzPg2r48AV5ASf934+4PiLMgMn6pSvwn9O4A== X-Google-Smtp-Source: ADUXVKLUNcEsPilIv05EfKfRozFCb1vzAVIFojdaYIYFkzyID+eH/btrxAUEs3RqFVGFRHG5f/oN69xtA8nsDLSnuo4= X-Received: by 2002:a1c:4a9d:: with SMTP id n29-v6mr2231916wmi.46.1528396764938; Thu, 07 Jun 2018 11:39:24 -0700 (PDT) MIME-Version: 1.0 References: <20180607143855.3681-1-yu-cheng.yu@intel.com> <20180607143855.3681-4-yu-cheng.yu@intel.com> In-Reply-To: <20180607143855.3681-4-yu-cheng.yu@intel.com> From: Andy Lutomirski Date: Thu, 7 Jun 2018 11:39:12 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 3/7] mm/mmap: Add IBT bitmap size to address space limit check To: Yu-cheng Yu Cc: LKML , linux-doc@vger.kernel.org, Linux-MM , linux-arch , X86 ML , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H. J. Lu" , "Shanbhogue, Vedvyas" , "Ravi V. Shankar" , Dave Hansen , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , mike.kravetz@oracle.com Content-Type: text/plain; charset="UTF-8" Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Jun 7, 2018 at 7:42 AM Yu-cheng Yu wrote: > > The indirect branch tracking legacy bitmap takes a large address > space. This causes may_expand_vm() failure on the address limit > check. For a IBT-enabled task, add the bitmap size to the > address limit. > > Signed-off-by: Yu-cheng Yu > --- > arch/x86/include/uapi/asm/resource.h | 5 +++++ > include/uapi/asm-generic/resource.h | 3 +++ > mm/mmap.c | 8 +++++++- > 3 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/uapi/asm/resource.h b/arch/x86/include/uapi/asm/resource.h > index 04bc4db8921b..0741b2a6101a 100644 > --- a/arch/x86/include/uapi/asm/resource.h > +++ b/arch/x86/include/uapi/asm/resource.h > @@ -1 +1,6 @@ > +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ > +#ifdef CONFIG_X86_INTEL_CET > +#define rlimit_as_extra() current->thread.cet.ibt_bitmap_size > +#endif > + > #include > diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h > index f12db7a0da64..8a7608a09700 100644 > --- a/include/uapi/asm-generic/resource.h > +++ b/include/uapi/asm-generic/resource.h > @@ -58,5 +58,8 @@ > # define RLIM_INFINITY (~0UL) > #endif > > +#ifndef rlimit_as_extra > +#define rlimit_as_extra() 0 > +#endif > > #endif /* _UAPI_ASM_GENERIC_RESOURCE_H */ > diff --git a/mm/mmap.c b/mm/mmap.c > index e7d1fcb7ec58..5c07f052bed7 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -3255,7 +3255,13 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, > */ > bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) > { > - if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) > + unsigned long as_limit = rlimit(RLIMIT_AS); > + unsigned long as_limit_plus = as_limit + rlimit_as_extra(); > + > + if (as_limit_plus > as_limit) > + as_limit = as_limit_plus; > + What happens if as_limit_plus overflows? I guess it's probably okay here. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html