Run 'usermode-agent' cause kernel panic on Powerpc
Benjamin Herrenschmidt
benh at kernel.crashing.org
Thu Dec 9 14:26:20 EST 2010
On Wed, 2010-12-08 at 09:20 +0800, xufeng zhang wrote:
> > I believe it would have such an impact. I don't see that user-mode
> > debugging would be enabled at all.
> >
> > Maybe something like this untested patch:
> >
> > diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> > index 84906d3..0e7d1cf 100644
> > --- a/arch/powerpc/kernel/process.c
> > +++ b/arch/powerpc/kernel/process.c
> > @@ -323,6 +323,13 @@ static void set_debug_reg_defaults(struct thread_struct *thread)
> >
> > static void prime_debug_regs(struct thread_struct *thread)
> > {
> > + /*
> > + * If we're setting up debug events for user space, make sure they
> > + * don't fire in kernel space before we get to user space
> > + */
> > + if (thread->dbcr0& DBCR0_IDM)
> > + mtmsr(mfmsr()& ~MSR_DE);
> > +
> > mtspr(SPRN_IAC1, thread->iac1);
> > mtspr(SPRN_IAC2, thread->iac2);
> > #if CONFIG_PPC_ADV_DEBUG_IACS> 2
> >
> >
> Thanks for your reply, Dave, I know where the problem is.
So is there a kernel bug we need to fix ?
Cheers,
Ben.
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