Re: [PATCH v2] x86: Remove compat vdso support

[H. Peter Anvin]

On 03/12/2014 02:49 PM, Andy Lutomirski wrote:
> On Wed, Mar 12, 2014 at 2:46 PM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>> On Wed, Mar 12, 2014 at 2:37 PM, H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> wrote:
>>>
>>> How would that deal with the legacy vsyscall case for x86-64?  Just rely
>>> on the "legacy vsyscall emulation" (which seems to have its own class of
>>> problems...)?
>>
>> It does?
>>
>> We *default* to emulation, and have for over two years now (since
>> v3.4).  If there are problems with it, we need to fix those.
> 
> Even in the non-default "vsyscall=native" case, the vsyscall pages
> just contains syscalls.  It does not need to access the vvar page, the
> hpet, or anything else that the vdso uses.
> 

Ah, right.  I let that detail slip the mind.

I do hear vsyscall=native still being used as a workaround for problems,
but yes, just making it call the kernel is fine, of course.

So yes, this does make it all better.

	-hpa


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