Re: SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386)

Linus Torvalds
2011-08-22T01:09:25Z

On Sun, Aug 21, 2011 at 5:44 PM, Andrew Lutomirski <luto@mit.edu> wrote:
>
> Which suggests an easy-ish fix: if sysenter is used or if syscall is
> entered from the EIP is is supposed to be entered from, then just
> change ip in the argument save to point to the int 0x80 instruction.

Indeed. Just add an "int 0x80" instruction to the vsyscall thing, and
you'd be done.

In fact, just replace the

jmp .Lenter_kernel

with

int 0x80

and you'd be pretty much all done, no?

(Ok, that's probably a huge over-simplification, but perhaps "close
enough" to true that it would be workable)

Linus