kernel virtual memory access (from app) does not generate segfault

[anfei]

On Tue, Jun 08, 2010 at 02:36:05PM +0100, Russell King - ARM Linux wrote:
> On Tue, Jun 08, 2010 at 09:29:40PM +0800, anfei wrote:
> > Hi Russell,
> > 
> > On Wed, Apr 21, 2010 at 09:11:49PM +0800, anfei wrote:
> > > Patch updated, and with comment log.
> > > 
> > > ===
> > > ARM: Proper prefetch abort handling on pre-ARMv6
> > > 
> > > Instruction faults on pre-ARMv6 CPUs are interpreted as
> > > a 'translation fault', but do_translation_fault doesn't
> > > handle well if user mode trying to run instruction above
> > > TASK_SIZE, and result in the infinite retry of that
> > > instruction.
> > > 
> > > Signed-off-by: Anfei Zhou <anfei.zhou at gmail.com>
> > > ---
> > >  arch/arm/mm/fault.c |    3 +++
> > >  1 files changed, 3 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
> > > index 9d40c34..8ad75e9 100644
> > > --- a/arch/arm/mm/fault.c
> > > +++ b/arch/arm/mm/fault.c
> > > @@ -393,6 +393,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
> > >  	if (addr < TASK_SIZE)
> > >  		return do_page_fault(addr, fsr, regs);
> > >  
> > > +	if (user_mode(regs))
> > > +		goto bad_area;
> > > +
> > >  	index = pgd_index(addr);
> > >  
> > >  	/*
> > 
> > This patch is still not into the mainline, will you plan to apply it?
> 
> I had, but as it isn't in the patch system, it got buried and forgotten.
> Could you submit it to the patch system please?  Just emailing it in
> a similar manner to that above, but with a subject of
> "Proper prefetch abort handling on pre-ARMv6" and an additional
> "KernelVersion: 2.6.whatever" line to the patch system should suffice.

Done, thanks!
Anfei.