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From: Alexander Potapenko <glider@google.com>
To: Will Deacon <will@kernel.org>
Cc: Marco Elver <elver@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	 "H. Peter Anvin" <hpa@zytor.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	 Andrey Konovalov <andreyknvl@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	 Andy Lutomirski <luto@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	 Catalin Marinas <catalin.marinas@arm.com>,
	Christoph Lameter <cl@linux.com>,
	 Dave Hansen <dave.hansen@linux.intel.com>,
	David Rientjes <rientjes@google.com>,
	 Dmitriy Vyukov <dvyukov@google.com>,
	Eric Dumazet <edumazet@google.com>,
	 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Hillf Danton <hdanton@sina.com>,  Ingo Molnar <mingo@redhat.com>,
	Jann Horn <jannh@google.com>,
	Jonathan.Cameron@huawei.com,  Jonathan Corbet <corbet@lwn.net>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	 Kees Cook <keescook@chromium.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Pekka Enberg <penberg@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	sjpark@amazon.com,  Thomas Gleixner <tglx@linutronix.de>,
	Vlastimil Babka <vbabka@suse.cz>,
	 "the arch/x86 maintainers" <x86@kernel.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	 LKML <linux-kernel@vger.kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>,
	 Linux ARM <linux-arm-kernel@lists.infradead.org>,
	 Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH v3 03/10] arm64, kfence: enable KFENCE for ARM64
Date: Mon, 21 Sep 2020 16:58:16 +0200	[thread overview]
Message-ID: <CAG_fn=WKaY9MVmbpkgoN4vaJYD_T_A3z2Lgqn+2o8-irmCKywg@mail.gmail.com> (raw)
In-Reply-To: <20200921143059.GO2139@willie-the-truck>

On Mon, Sep 21, 2020 at 4:31 PM Will Deacon <will@kernel.org> wrote:
>
> On Mon, Sep 21, 2020 at 03:26:04PM +0200, Marco Elver wrote:
> > Add architecture specific implementation details for KFENCE and enable
> > KFENCE for the arm64 architecture. In particular, this implements the
> > required interface in <asm/kfence.h>. Currently, the arm64 version does
> > not yet use a statically allocated memory pool, at the cost of a pointer
> > load for each is_kfence_address().
> >
> > Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> > Co-developed-by: Alexander Potapenko <glider@google.com>
> > Signed-off-by: Alexander Potapenko <glider@google.com>
> > Signed-off-by: Marco Elver <elver@google.com>
> > ---
> > For ARM64, we would like to solicit feedback on what the best option is
> > to obtain a constant address for __kfence_pool. One option is to declare
> > a memory range in the memory layout to be dedicated to KFENCE (like is
> > done for KASAN), however, it is unclear if this is the best available
> > option. We would like to avoid touching the memory layout.
>
> Sorry for the delay on this.

NP, thanks for looking!

> Given that the pool is relatively small (i.e. when compared with our virtual
> address space), dedicating an area of virtual space sounds like it makes
> the most sense here. How early do you need it to be available?

Yes, having a dedicated address sounds good.
We're inserting kfence_init() into start_kernel() after timekeeping_init().
So way after mm_init(), if that matters.

> An alternative approach would be to patch in the address at runtime, with
> something like a static key to swizzle off the direct __kfence_pool load
> once we're up and running.

IIUC there's no such thing as address patching in the kernel at the
moment, at least static keys work differently?
I am not sure how much we need to randomize this address range (we
don't on x86 anyway).

> Will
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20200921143059.GO2139%40willie-the-truck.



--
Alexander Potapenko
Software Engineer

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  reply	other threads:[~2020-09-21 14:58 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-21 13:26 [PATCH v3 00/10] KFENCE: A low-overhead sampling-based memory safety error detector Marco Elver
2020-09-21 13:26 ` [PATCH v3 01/10] mm: add Kernel Electric-Fence infrastructure Marco Elver
2020-09-25 11:23   ` SeongJae Park
2020-09-25 11:31     ` Marco Elver
2020-09-29 12:42   ` Andrey Konovalov
2020-09-29 13:11     ` Marco Elver
2020-09-29 13:48       ` Andrey Konovalov
2020-09-29 13:49         ` Marco Elver
2020-09-29 14:01           ` Andrey Konovalov
2020-09-29 14:24   ` Mark Rutland
2020-09-29 14:51     ` Marco Elver
2020-09-29 15:05       ` Mark Rutland
2020-10-05 16:00         ` Alexander Potapenko
2020-10-05 16:49           ` Jann Horn
2020-09-29 15:51     ` Alexander Potapenko
2020-10-01 18:11       ` Mark Rutland
2020-09-21 13:26 ` [PATCH v3 02/10] x86, kfence: enable KFENCE for x86 Marco Elver
2020-09-21 13:26 ` [PATCH v3 03/10] arm64, kfence: enable KFENCE for ARM64 Marco Elver
2020-09-21 14:31   ` Will Deacon
2020-09-21 14:58     ` Alexander Potapenko [this message]
2020-09-21 15:37       ` Alexander Potapenko
2020-09-21 17:43         ` Will Deacon
2020-09-22  9:56           ` Marco Elver
2020-09-29 13:53             ` Mark Rutland
2020-09-29 16:52               ` Alexander Potapenko
2020-09-25 15:25     ` Alexander Potapenko
2020-09-29 14:02       ` Mark Rutland
2020-10-01 11:24         ` Alexander Potapenko
2020-10-01 17:57           ` Mark Rutland
2020-10-08  9:40             ` Marco Elver
2020-10-08 10:45               ` Mark Rutland
2020-10-14 19:12                 ` Marco Elver
2020-10-15 13:39                   ` Mark Rutland
2020-10-15 14:15                     ` Marco Elver
2020-09-28 11:53     ` Marco Elver
2020-09-29 14:27   ` Mark Rutland
2020-09-29 17:04     ` Alexander Potapenko
2020-09-21 13:26 ` [PATCH v3 04/10] mm, kfence: insert KFENCE hooks for SLAB Marco Elver
2020-09-21 13:26 ` [PATCH v3 05/10] mm, kfence: insert KFENCE hooks for SLUB Marco Elver
2020-09-21 13:26 ` [PATCH v3 06/10] kfence, kasan: make KFENCE compatible with KASAN Marco Elver
2020-09-29 12:20   ` Andrey Konovalov
2020-09-29 13:13     ` Alexander Potapenko
2020-09-21 13:26 ` [PATCH v3 07/10] kfence, kmemleak: make KFENCE compatible with KMEMLEAK Marco Elver
2020-09-21 13:26 ` [PATCH v3 08/10] kfence, lockdep: make KFENCE compatible with lockdep Marco Elver
2020-09-21 13:26 ` [PATCH v3 09/10] kfence, Documentation: add KFENCE documentation Marco Elver
2020-09-21 13:26 ` [PATCH v3 10/10] kfence: add test suite Marco Elver
2020-09-21 17:13   ` Paul E. McKenney
2020-09-21 17:37     ` Marco Elver
2020-09-21 17:48       ` Paul E. McKenney
2020-09-21 13:38 ` [PATCH v3 00/10] KFENCE: A low-overhead sampling-based memory safety error detector Dmitry Vyukov

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