Re: CVS commit: src/sys/arch

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Sat, Jul 01, 2017 at 10:44:43AM +0000, Maxime Villard wrote:
> Module Name:	src
> Committed By:	maxv
> Date:		Sat Jul  1 10:44:43 UTC 2017
> 
> Modified Files:
> 	src/sys/arch/amd64/amd64: locore.S
> 	src/sys/arch/i386/i386: locore.S machdep.c trap.c
> 
> Log Message:
> Remove the osyscall call gate on i386, and emulate it. There is a one-
> instruction race in it that could panic the kernel.

Looking back at this -- can't we provide a user-readable/executable page
and replace the call gate with a normal segment pointing to that page?
So that osycall becomes a normal FAR CALL to a kernel provide routine
that turns it into a normal system call. That has the advantage of not
requiring special case logic in the trap handler and I want to move the
direct system call logic out of libc in the near future, which requires
the same infrastructure.

Joerg