Re: [PATCH v2 0/6] mm, x86/vdso: Special IO mapping improvements

[Andy Lutomirski <luto@amacapital.net>]

On Wed, Dec 23, 2015 at 3:56 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> Hi Oleg and Kees-
>
> I meant to cc you on this in the first place, but I failed.  If you
> have a few minutes, want to take a peek at these and see if you can
> poke any holes in them?  I'm reasonably confident that they're a
> considerable improvement over the old state of affairs, but they might
> still not be perfect.
>
> Let me know if you want me to email out a fresh copy.  This series
> applies to tip:x86/asm.

Hi -tip people:

please don't apply this series.  It has a race.  I'll send v3.

--Andy

>
> --Andy
>
> On Mon, Dec 14, 2015 at 10:31 AM, Andy Lutomirski <luto@kernel.org> wrote:
>> This applies on top of the earlier vdso pvclock series I sent out.
>> Once that lands in -tip, this will apply to -tip.
>>
>> This series cleans up the hack that is our vvar mapping.  We currently
>> initialize the vvar mapping as a special mapping vma backed by nothing
>> whatsoever and then we abuse remap_pfn_range to populate it.
>>
>> This cheats the mm core, probably breaks under various evil madvise
>> workloads, and prevents handling faults in more interesting ways.
>>
>> To clean it up, this series:
>>
>>  - Adds a special mapping .fault operation
>>  - Adds a vm_insert_pfn_prot helper
>>  - Uses the new .fault infrastructure in x86's vdso and vvar mappings
>>  - Hardens the HPET mapping, mitigating an HW attack surface that bothers me
>>
>> akpm, can you ack patck 1?
>>
>> Changes from v1:
>>  - Lots of changelog clarification requested by akpm
>>  - Minor tweaks to style and comments in the first two patches
>>
>> Andy Lutomirski (6):
>>   mm: Add a vm_special_mapping .fault method
>>   mm: Add vm_insert_pfn_prot
>>   x86/vdso: Track each mm's loaded vdso image as well as its base
>>   x86,vdso: Use .fault for the vdso text mapping
>>   x86,vdso: Use .fault instead of remap_pfn_range for the vvar mapping
>>   x86/vdso: Disallow vvar access to vclock IO for never-used vclocks
>>
>>  arch/x86/entry/vdso/vdso2c.h            |   7 --
>>  arch/x86/entry/vdso/vma.c               | 124 ++++++++++++++++++++------------
>>  arch/x86/entry/vsyscall/vsyscall_gtod.c |   9 ++-
>>  arch/x86/include/asm/clocksource.h      |   9 +--
>>  arch/x86/include/asm/mmu.h              |   3 +-
>>  arch/x86/include/asm/vdso.h             |   3 -
>>  arch/x86/include/asm/vgtod.h            |   6 ++
>>  include/linux/mm.h                      |   2 +
>>  include/linux/mm_types.h                |  22 +++++-
>>  mm/memory.c                             |  25 ++++++-
>>  mm/mmap.c                               |  13 ++--
>>  11 files changed, 151 insertions(+), 72 deletions(-)
>>
>> --
>> 2.5.0
>>
>
>
>
> --
> Andy Lutomirski
> AMA Capital Management, LLC



-- 
Andy Lutomirski
AMA Capital Management, LLC

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