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From:   Alexander Potapenko <glider@google.com>
Date:   Fri, 25 Sep 2020 17:25:11 +0200
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Subject: Re: [PATCH v3 03/10] arm64, kfence: enable KFENCE for ARM64
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>,
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        Andy Lutomirski <luto@kernel.org>,
        Borislav Petkov <bp@alien8.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
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Will,

> 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?

How do we assign struct pages to a fixed virtual space area (I'm
currently experimenting with 0xffff7f0000000000-0xffff7f0000200000)?
Looks like filling page table entries (similarly to what's being done
in arch/arm64/mm/kasan_init.c) is not enough.
I thought maybe vmemmap_populate() would do the job, but it didn't
(virt_to_pfn() still returns invalid PFNs).