From: Catalin Marinas <catalin.marinas@arm.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andrey Konovalov <andreyknvl@google.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Memory Management List <linux-mm@kvack.org>,
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kvm@vger.kernel.org,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will.deacon@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kees Cook <keescook@chromium.org>,
Yishai Hadas <yishaih@mellanox.com>,
Felix Kuehling <Felix.Kuehling@amd.com>,
Alexander Deucher <Alexander.Deucher@amd.com>,
Christian Koenig <Christian.Koenig@amd.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Jens Wiklander <jens.wiklander@linaro.org>,
Alex Williamson <alex.williamson@redhat.com>,
Leon Romanovsky <leon@kernel.org>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Dave Martin <Dave.Martin@arm.com>,
Khalid Aziz <khalid.aziz@oracle.com>, enh <enh@google.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
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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>,
Robin Murphy <robin.murphy@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Subject: Re: [PATCH v19 00/15] arm64: untag user pointers passed to the kernel
Date: Fri, 2 Aug 2019 11:20:32 +0100 [thread overview]
Message-ID: <20190802102031.GB4175@arrakis.emea.arm.com> (raw)
In-Reply-To: <96fd8da4-a912-f6cc-2b32-5791027dbbd5@intel.com>
On Thu, Aug 01, 2019 at 08:36:47AM -0700, Dave Hansen wrote:
> On 8/1/19 5:48 AM, Andrey Konovalov wrote:
> > On Thu, Aug 1, 2019 at 2:11 PM Kevin Brodsky <kevin.brodsky@arm.com> wrote:
> >> On 31/07/2019 17:50, Dave Hansen wrote:
> >>> On 7/23/19 10:58 AM, Andrey Konovalov wrote:
> >>>> The mmap and mremap (only new_addr) syscalls do not currently accept
> >>>> tagged addresses. Architectures may interpret the tag as a background
> >>>> colour for the corresponding vma.
> >>>
> >>> What the heck is a "background colour"? :)
> >>
> >> Good point, this is some jargon that we started using for MTE, the idea being that
> >> the kernel could set a tag value (specified during mmap()) as "background colour" for
> >> anonymous pages allocated in that range.
> >>
> >> Anyway, this patch series is not about MTE. Andrey, for v20 (if any), I think it's
> >> best to drop this last sentence to avoid any confusion.
Indeed, the part with the "background colour" and even the "currently"
adverb should be dropped.
Also, if we merge the patches via different trees anyway, I don't think
there is a need for Andrey to integrate them with his series. We can
pick them up directly in the arm64 tree (once the review finished).
> OK, but what does that mean for tagged addresses getting passed to
> mmap/mremap? That sentence read to me like "architectures might allow
> tags for ...something...". So do we accept tagged addresses into those
> syscalls?
If mmap() does not return a tagged address, the reasoning is that it
should not accept one as an address hint (with or without MAP_FIXED).
Note that these docs should only describe the top-byte-ignore ABI while
leaving the memory tagging for a future patchset.
In that future patchset, we may want to update the mmap() ABI to allow,
only in conjunction with PROT_MTE, a tagged pointer as an address
argument. In such case mmap() will return a tagged address and the pages
pre-coloured (on fault) with the tag requested by the user. As I said,
that's to be discussed later in the year.
--
Catalin
prev parent reply other threads:[~2019-08-02 10:20 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-23 17:58 [PATCH v19 00/15] arm64: untag user pointers passed to the kernel Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 01/15] arm64: untag user pointers in access_ok and __uaccess_mask_ptr Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI Andrey Konovalov
2019-07-31 17:05 ` Dave Hansen
2019-08-01 12:38 ` Kevin Brodsky
2019-08-01 16:45 ` Dave Hansen
2019-08-02 10:50 ` Catalin Marinas
2019-08-09 16:08 ` Catalin Marinas
2019-07-23 17:58 ` [PATCH v19 03/15] lib: untag user pointers in strn*_user Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 04/15] mm: untag user pointers passed to memory syscalls Andrey Konovalov
2019-08-09 16:03 ` Catalin Marinas
2019-07-23 17:58 ` [PATCH v19 05/15] mm: untag user pointers in mm/gup.c Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 06/15] mm: untag user pointers in get_vaddr_frames Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 07/15] fs/namespace: untag user pointers in copy_mount_options Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 08/15] userfaultfd: untag user pointers Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 09/15] drm/amdgpu: " Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 10/15] drm/radeon: untag user pointers in radeon_gem_userptr_ioctl Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 11/15] IB/mlx4: untag user pointers in mlx4_get_umem_mr Andrey Konovalov
2019-07-24 19:25 ` Jason Gunthorpe
2019-07-25 11:17 ` Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 12/15] media/v4l2-core: untag user pointers in videobuf_dma_contig_user_get Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 13/15] tee/shm: untag user pointers in tee_shm_register Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 14/15] vfio/type1: untag user pointers in vaddr_get_pfn Andrey Konovalov
2019-07-23 17:58 ` [PATCH v19 15/15] selftests, arm64: add a selftest for passing tagged pointers to kernel Andrey Konovalov
2019-07-23 18:03 ` [PATCH v19 00/15] arm64: untag user pointers passed to the kernel Andrey Konovalov
2019-07-24 14:02 ` Will Deacon
2019-07-24 14:16 ` Andrey Konovalov
2019-07-24 14:20 ` Will Deacon
2019-07-24 17:12 ` Vincenzo Frascino
2019-08-06 17:13 ` Will Deacon
2019-08-07 17:17 ` Andrey Konovalov
2019-08-08 21:12 ` Kees Cook
2019-08-08 22:33 ` Andrew Morton
2019-08-08 23:09 ` Kees Cook
2019-08-09 9:00 ` Catalin Marinas
2019-08-09 9:28 ` Dave Martin
2019-07-25 13:50 ` [PATCH v6 0/2] arm64 relaxed ABI Vincenzo Frascino
2019-07-25 13:50 ` [PATCH v6 1/2] arm64: Define Documentation/arm64/tagged-address-abi.rst Vincenzo Frascino
2019-07-30 10:32 ` Kevin Brodsky
2019-07-30 13:25 ` Vincenzo Frascino
2019-07-30 13:57 ` Kevin Brodsky
2019-07-30 14:24 ` Vincenzo Frascino
2019-07-30 14:48 ` Kevin Brodsky
2019-07-31 16:43 ` Dave Hansen
2019-08-02 10:08 ` Catalin Marinas
2019-07-25 13:50 ` [PATCH v6 2/2] arm64: Relax Documentation/arm64/tagged-pointers.rst Vincenzo Frascino
2019-07-31 16:50 ` [PATCH v19 00/15] arm64: untag user pointers passed to the kernel Dave Hansen
2019-08-01 12:11 ` Kevin Brodsky
2019-08-01 12:48 ` Andrey Konovalov
2019-08-01 15:36 ` Dave Hansen
2019-08-02 10:20 ` Catalin Marinas [this message]
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