On Fri, Apr 11, 2014 at 1:54 PM, Russell King - ARM Linux <[email protected]> wrote: > On Fri, Apr 11, 2014 at 01:50:50PM +0200, Miklos Szeredi wrote: >> On Fri, Apr 11, 2014 at 12:33 PM, Russell King - ARM Linux >> <[email protected]> wrote: >> > On Fri, Apr 11, 2014 at 12:25:38PM +0200, Miklos Szeredi wrote: >> >> From: Miklos Szeredi <[email protected]> >> >> >> >> Signed-off-by: Miklos Szeredi <[email protected]> >> >> Cc: Russell King <[email protected]> >> >> --- >> > >> > 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. > > Please explain.
Look at ending lines of arch/arm/kernel/calls.S: if NR_syscalls is a multiple of 4, then syscalls_padding will be zero. I.e. no padding despite the fact that there is in fact only 382 system calls in table and there should be 2 sys_ni_syscall pads. So there's some crap in there, for sure. If it causes actual problems, I don't know. Thanks, Miklos -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
