Re: CVS commit: src/sys/arch

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 18/08/2017 à 13:19, coypu%sdf.org@localhost a écrit :
> On Fri, Aug 18, 2017 at 10:02:37AM +0000, Maxime Villard wrote:
> > Remove unused and broken code. On amd64 we won't want int3 from kernel
> > mode to be valid.
> > -	/*
> > -	 * DTrace Function Boundary Trace (fbt) probes are triggered
> > -	 * by int3 (0xcc).
> > -	 */
>
> Is there some other trap instruction that could be used? the removal of
> dtrace functions breaks the ability to load the dtrace module.
I've reverted my change. The symbols are used by the kernel module in
src/external/, and I didn't check carefully enough. I had thought that the
callbacks were generic C functions, and they obviously wouldn't have worked.

While it seems to be not totally broken as is, it really is a bad design
to have the trap frame constructed in a kernel module hidden in src/external.
By the way, I don't see where segment registers are saved on i386. And at a
time, we could have come from userland via vm86 and it wasn't checked. And in
amd64 we don't check for userland at all. Etc.

Maxime