RE: [PATCH] m68k: Implement "current_stack_pointer"

[David Laight]

From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Sent: 24 February 2022 09:17
> 
> On Thu, Feb 24, 2022 at 10:12 AM David Laight <David.Laight@xxxxxxxxxx> wrote:
> > From: Geert Uytterhoeven
> > > Sent: 24 February 2022 08:59
> > ...
> > > > +register unsigned long current_stack_pointer __asm__("sp");
> > >
> > > I don't know what HARDENED_USERCOPY does, so I don't know if you need
> > > "usp" (see rdusp()) or "sp"?
> >
> > HARDENED_USERCOPY significantly slows down some systems calls
> > (especially things like sendmsg()) by trying to run-time verify
> > that the kernel buffer doesn't overrun a stack frame or kmalloc()ed
> 
> Kernel stack frame of user stack frame?

Kernel, the kernel doesn't care if the user stack gets trashed.

	David

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