[PATCH] arm64: mark kernel text segment as MEMBLOCK_NOMAP

Ard Biesheuvel ard.biesheuvel at linaro.org
Mon Feb 15 09:17:46 PST 2016


On 15 February 2016 at 13:08, Catalin Marinas <catalin.marinas at arm.com> wrote:
> On Mon, Feb 15, 2016 at 12:53:59PM +0100, Ard Biesheuvel wrote:
>> On 15 February 2016 at 12:45, Catalin Marinas <catalin.marinas at arm.com> wrote:
>> > Ard, I'm about to drop the kernel memory map patches from -next. There
>> > are several issues like KASAN (which may as well be a KASAN bug but I
>> > haven't got to the bottom of it yet), initrd (you have patches but
>> > require additional acks).
>> >
>> > I'll keep your stuff on the for-next/kernmap branch and do further
>> > debugging. If it stabilises in the next 1-2 weeks, I'll merge it into
>> > for-next/core for 4.6, otherwise, it will have to wait. I would really
>> > like these patches merged but it looks like they need wider testing.
> [...]
>> If you are going to drop it for now anyway, I can do a v6sub1 with
>> this issue and the initrd issue addressed, but also an issue with the
>> KVM ksym ref patch with GCC 4.8. Since these issues affect
>> bisectability, I'd prefer to rebase entirely, and fold all the fixes
>> rather than apply them on top.
>
> That's fine. I'll push one more patch to the for-next/pgtable branch,
> converting __set_fixmap_offset() back to a macro as it broke other
> architectures. Otherwise it is not rebased and I'll merge it into
> for-next core.
>

I have identified (and fixed) a Kasan issue in my patches: instead of
leaving a hole for the 64 MB module window in the Kasan shadow region,
I populated it with zero mappings, which caused many strange errors,
and since the vmap() routines don't expect block mappings (which are
created for the kernel image shadow by vmemmap_populate()), I guess
false positive kasan warnings (like the ones you were seeing) are also
a possible symptom of this issue.

-- 
Ard.



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