Re: [PATCH v7 33/41] x86/shstk: Introduce map_shadow_stack syscall

[Edgecombe, Rick P]

On Fri, 2023-03-10 at 17:11 +0100, Borislav Petkov wrote:

[...]

Thanks on all the text edits.

> On Mon, Feb 27, 2023 at 02:29:49PM -0800, Rick Edgecombe wrote:
> > diff --git a/arch/x86/entry/syscalls/syscall_64.tbl
> > b/arch/x86/entry/syscalls/syscall_64.tbl
> > index c84d12608cd2..f65c671ce3b1 100644
> > --- a/arch/x86/entry/syscalls/syscall_64.tbl
> > +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> > @@ -372,6 +372,7 @@
> >  448	common	process_mrelease	sys_process_mreleas
> > e
> >  449	common	futex_waitv		sys_futex_waitv
> >  450	common	set_mempolicy_home_node	sys_set_mempolicy_h
> > ome_node
> > +451	64	map_shadow_stack	sys_map_shadow_stack
> 
> Yeah, this'll need a manpage too, I presume. But later.

I have one to submit.

[...]

> > +
> > +	if (addr && addr <= 0xFFFFFFFF)
> 
> 			< SZ_4G
> 
> > +		return -EINVAL;
> 
> Can we use distinct negative retvals in each case so that it is clear
> to
> userspace where it fails, *if* it fails?

Good idea, I think maybe ERANGE.