Re: RFD: x32 ABI system call numbers

[H. Peter Anvin]

On 08/31/2011 09:46 AM, Linus Torvalds wrote:
> On Wed, Aug 31, 2011 at 9:14 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
>>
>> * padding in struct timespec when you have a long long tv_sec and
>>  32-bit long tv_nsec. This might cause kernel stack data leakage
>>  in some kernel interfaces when they don't clear the padding.
> 
> I suspect only sane solution to this (having thought about it some
> more) is to just say "POSIX is f*^&ing wrong".
> 

Urk.  Someone had the bright idea of defining tv_nsec as "long" in the
standard, whereas tv_usec is suseconds_t.  F**** brilliant, and more
than a little bit stupid.

Logically one could work around it by having "struct timespec" contain a
padding member in the endian-appropriate place I guess, and make sure to
clear it in the kernel, but it's rather ugly.  It might have performance
advantages to doing it that way, though.

> I really think that "x32" should try to aim *VERY* hard at using the
> 64-bit system calls, and seeing itself as being a "32-bit application
> in a 64-bit world".  That's not just true for time_t (which I think
> should be 64-bit on anything new that expects to survive for any
> amount of time), but in general.

We're trying for it.  The things we're trying to avoid is to muck (too
much) with the compat layer for the mega-multiplex system calls like
ioctl.  We can't just use the 64-bit ioctl because ioctl structures
generally contain pointers.

	-hpa

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