syscall trap patch review

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

I plan to commit this in order to greatly improve COMPAT_MACH
performance on the PowerPC. Someone can review it to make sure it is
okay?

The goal is to quickly return from two system calls, returning no error.

Index: trap_subr.S
===================================================================
RCS file: /cvsroot/syssrc/sys/arch/powerpc/powerpc/trap_subr.S,v
retrieving revision 1.29
diff -r1.29 trap_subr.S
40a41
> #include "opt_compat_mach.h"
720a722,726
> #ifdef COMPAT_MACH
> /* Handle Mach fast traps: Do nothing but do it quickly */
>       cmpwi   5,0,0x7ff2      # cthread_info
>       cmpwi   6,0,0x7ff1      # cthread_set_self
> #endif
723a730,733
> #ifdef COMPAT_MACH
>       beq     5,2f
>       beq     6,2f
> #endif
747a758,768
> #ifdef COMPAT_MACH
> 2:
>       FRAME_LEAVE(tempsave)
>       mfcr    3
>       lis     4,0x1000
>       ori     3,3,4
>       mtcr    3
>       li      3,0
>       li      4,0
>       rfi
> #endif


-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost