From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH v10 07/12] fs, arm64: untag user pointers in
 fs/userfaultfd.c
Date: Fri, 22 Feb 2019 15:05:51 -0800
Message-ID: <73f2f3fe-9a66-22a1-5aae-c282779a75f5@intel.com>
References: <cover.1550839937.git.andreyknvl@google.com>
 <8343cd77ca301df15839796f3b446b75ce5ffbbf.1550839937.git.andreyknvl@google.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <8343cd77ca301df15839796f3b446b75ce5ffbbf.1550839937.git.andreyknvl@google.com>
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
To: Andrey Konovalov <andreyknvl@google.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com>, Robin Murphy <robin.murphy@arm.com>, Kees Cook <keescook@chromium.org>, Kate Stewart <kstewart@linuxfoundation.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@kernel.org>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Shuah Khan <shuah@kernel.org>, Vincenzo Frascino <vincenzo.frascino@arm.com>, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Dmitry Vyukov <dvyukov@google.com>, Kostya Serebryany <kcc@google.com>, Evgeniy Stepanov <eugenis@google.com>, Lee Smith <Lee.Smith@arm.com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>, Jacob Bramley <Jacob.Bramley@arm.com>, Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>, Chintan Pandya <cpandya@codeaurora.org>, Luc Van Oostenryck <luc.vanoostenryck@gmail.com>, Dave Martin <Dave.Martin@arm.com>, Kevin Brodsky <kevin.brodsky@arm.com>, Szabolcs Nagy <Szabolcs.Nagy@arm.com>
List-Id: linux-arch.vger.kernel.org

On 2/22/19 4:53 AM, Andrey Konovalov wrote:
> userfaultfd_register() and userfaultfd_unregister() use provided user
> pointers for vma lookups, which can only by done with untagged pointers.

So, we have to patch all these sites before the tagged values get to the
point of hitting the vma lookup functions.  Dumb question: Why don't we
just patch the vma lookup functions themselves instead of all of these
callers?

From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-arch-owner@vger.kernel.org>
Received: from mga02.intel.com ([134.134.136.20]:16641 "EHLO mga02.intel.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1725900AbfBVXFw (ORCPT <rfc822;linux-arch@vger.kernel.org>);
        Fri, 22 Feb 2019 18:05:52 -0500
Subject: Re: [PATCH v10 07/12] fs, arm64: untag user pointers in
 fs/userfaultfd.c
References: <cover.1550839937.git.andreyknvl@google.com>
 <8343cd77ca301df15839796f3b446b75ce5ffbbf.1550839937.git.andreyknvl@google.com>
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <73f2f3fe-9a66-22a1-5aae-c282779a75f5@intel.com>
Date: Fri, 22 Feb 2019 15:05:51 -0800
MIME-Version: 1.0
In-Reply-To: <8343cd77ca301df15839796f3b446b75ce5ffbbf.1550839937.git.andreyknvl@google.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-arch-owner@vger.kernel.org
List-ID: <linux-arch.vger.kernel.org>
To: Andrey Konovalov <andreyknvl@google.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com>, Robin Murphy <robin.murphy@arm.com>, Kees Cook <keescook@chromium.org>, Kate Stewart <kstewart@linuxfoundation.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@kernel.org>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Shuah Khan <shuah@kernel.org>, Vincenzo Frascino <vincenzo.frascino@arm.com>, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Dmitry Vyukov <dvyukov@google.com>, Kostya Serebryany <kcc@google.com>, Evgeniy Stepanov <eugenis@google.com>, Lee Smith <Lee.Smith@arm.com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>, Jacob Bramley <Jacob.Bramley@arm.com>, Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>, Chintan Pandya <cpandya@codeaurora.org>, Luc Van Oostenryck <luc.vanoostenryck@gmail.com>, Dave Martin <Dave.Martin@arm.com>, Kevin Brodsky <kevin.brodsky@arm.com>, Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Message-ID: <20190222230551._XyvDMUVN68doRoFodt-N50Qb33y0ktjYsDWw2IRezs@z>

On 2/22/19 4:53 AM, Andrey Konovalov wrote:
> userfaultfd_register() and userfaultfd_unregister() use provided user
> pointers for vma lookups, which can only by done with untagged pointers.

So, we have to patch all these sites before the tagged values get to the
point of hitting the vma lookup functions.  Dumb question: Why don't we
just patch the vma lookup functions themselves instead of all of these
callers?