[PATCH] [RFC] Emulate "lwsync" to run standard user land on e500 cores

[Scott Wood]

On Wed, 2013-10-23 at 00:07 -0500, Kumar Gala wrote:
> On Oct 18, 2013, at 2:38 AM, Wolfgang Denk wrote:
> > diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> > index f783c93..f330374 100644
> > --- a/arch/powerpc/kernel/traps.c
> > +++ b/arch/powerpc/kernel/traps.c
> > @@ -986,6 +986,13 @@ static int emulate_instruction(struct pt_regs *regs)
> > 		return 0;
> > 	}
> > 
> > +	/* Emulating the lwsync insn as a sync insn */
> > +	if (instword == PPC_INST_LWSYNC) {
> > +		PPC_WARN_EMULATED(lwsync, regs);
> > +		asm volatile("sync" : : : "memory");
> 
> Do we really need the inline asm?  Doesn't the fact of just taking an exception and returning from it equate to a sync.

No, it doesn't equate to a sync.  See the discussion here:
http://patchwork.ozlabs.org/patch/256747/

-Scott