[parisc-linux] ldcw in __pthread_acquire

[LaMont Jones]

> Since hppa its apparently 2 clocks to the syscall the numbers are apparently
> different.

Actually, the sequence consists of:

libc_stub:
	bl	gateway_page_addr
	...

gateway_page_addr:
	gate	.+8
	...
	...

And we find ourselves in kernel mode after 2 branches (unconditional
and pre-computed ==> predict correctly) and two delay slots.  At that
point we have kernel data structures at our fingertips, but have in no
way done a complete 'syscall' entry - those are (at least on hp-ux) a
bit more expensive...  (It also means that kernel vs user detection in
traps code needs to look at the priv level, not the stack pointer...)

lamont