[PATCH v2] x32: Implement prctl in assembly

[Florian Weimer]

* H. J. Lu:
> Here is the v2 patch to implement prctl in assembly for x32.
>
> Since the variadic prctl function takes at most 5 integer arguments which
> are passed in the same integer registers on x32 as the function with 5
> integer arguments, we can use assembly for prctl.  Since upper 32-bits in
> the last 4 arguments of prctl must be cleared to match the x32 prctl
> syscall interface where the last 4 arguments are unsigned 64 bit longs,
> implement prctl in assembly to clear upper 32-bits in the last 4 arguments
> and add a test to verify it.

What's the advantage of the assembler implementation over the C
implementation?  I'm missing the context for this change.

Thanks,
Florian