Re: Need help in understanding x86 syscall

Steven Rostedt
2005-08-11T18:11:11Z

On Thu, 2005-08-11 at 13:46 -0400, linux-os (Dick Johnson) wrote:

>
> I was talking about the one who had the glibc support to use
> the newer system-call entry (who's name can confuse).
>
> You are looking at code that uses int 0x80. It's an interrupt,
> therefore, in the kernel, once the stack is set up, interrupts
> need to be (re)enabled.

int is a call to either an interrupt or exception procedure. 0x80 is
setup in Linux to be a trap and not an interrupt vector. So it does
_not_ turn off interrupts.

I'm looking at the sysenter code which is suppose to be the fast entry
into the system, and it looks like it is suppose to call the
sysenter_entry when used. I'm trying to write something to test this
out, since I still have the ud2 op in my sysentry code. So if I do get
this to work, I can cause a bug.

-- Steve