From: Mark Rutland <mark.rutland@arm.com>
To: Marco Elver <elver@google.com>
Cc: Will Deacon <will@kernel.org>,
Alexander Potapenko <glider@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 <Jonathan.Cameron@huawei.com>,
Jonathan Corbet <corbet@lwn.net>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Kees Cook <keescook@chromium.org>,
Pekka Enberg <penberg@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
SeongJae Park <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: Tue, 29 Sep 2020 14:53:55 +0100 [thread overview]
Message-ID: <20200929135355.GA53442@C02TD0UTHF1T.local> (raw)
In-Reply-To: <CANpmjNNdGWoY_FcqUDUZ2vXy840H2+LGzN3WWrK8iERTKntSTw@mail.gmail.com>
On Tue, Sep 22, 2020 at 11:56:26AM +0200, Marco Elver wrote:
> On Mon, 21 Sep 2020 at 19:44, Will Deacon <will@kernel.org> wrote:
> [...]
> > > > > > 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.
> > >
> > > The question is though, how big should that dedicated area be?
> > > Right now KFENCE_NUM_OBJECTS can be up to 16383 (which makes the pool
> > > size 64MB), but this number actually comes from the limitation on
> > > static objects, so we might want to increase that number on arm64.
> >
> > What happens on x86 and why would we do something different?
>
> On x86 we just do `char __kfence_pool[KFENCE_POOL_SIZE] ...;` to
> statically allocate the pool. On arm64 this doesn't seem to work
> because static memory doesn't have struct pages?
Are you using virt_to_page() directly on that statically-allocated
__kfence_pool? If so you'll need to use lm_alias() if so, as is done in
mm/kasan/init.c.
Anything statically allocated is part of the kernel image address range
rather than the linear/direct map, and doesn't have a valid virt addr,
but its linear map alias does.
If you enable CONFIG_DEBUG_VIRTUAL you should get warnings if missing
lm_alias() calls.
Thanks,
Mark.
next prev parent reply other threads:[~2020-09-29 13:54 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
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 [this message]
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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