Re: [PATCH 02/15] arm: __NR_syscalls fix

[Miklos Szeredi]

On Fri, Apr 11, 2014 at 12:33 PM, Russell King - ARM Linux
<linux@xxxxxxxxxxxxxxxx> wrote:
> On Fri, Apr 11, 2014 at 12:25:38PM +0200, Miklos Szeredi wrote:
>> From: Miklos Szeredi <mszeredi@xxxxxxx>
>>
>> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
>> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
>> ---
>
> This has me wondering...
>
> (a) what you think it fixes
> (b) whether you tried to build-test this
>
> The ARM instruction set supports 8-bit immediate constants with an even
> power of two shift.  384 fits that (0x180), 382 does not (0x17e), and
> in your following patch, 383 definitely doesn't (0x17f).
>
> Having this constant larger than necessary does not cause any problem
> for the syscall table: we explicitly pad it with calls to sys_ni_syscall
> to make up the difference.

Yes, and the padding will be of wrong length if NR_syscalls is
incorrect (which may be Oopsable?).  At least that is my impression
from a casual glance.

Thanks,
Miklos
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