On Thu, May 27, 2010 at 04:20:44PM +1000, Paul Mackerras wrote:
> On Tue, May 25, 2010 at 02:44:35PM +0530, K.Prasad wrote:
>
> > An alignment interrupt may intervene between a DSI/hw-breakpoint exception
> > and the single-step exception. Enable the alignment interrupt (through
> > modifications to emulate_single_step()) to notify the single-step exception
> > handler for proper restoration of hw-breakpoints.
> >
> > Signed-off-by: K.Prasad <pra...@linux.vnet.ibm.com>
> > ---
> > arch/powerpc/kernel/traps.c | 7 ++-----
> > 1 file changed, 2 insertions(+), 5 deletions(-)
> >
> > Index: linux-2.6.ppc64_test/arch/powerpc/kernel/traps.c
> > ===================================================================
> > --- linux-2.6.ppc64_test.orig/arch/powerpc/kernel/traps.c
> > +++ linux-2.6.ppc64_test/arch/powerpc/kernel/traps.c
> > @@ -602,7 +602,7 @@ void RunModeException(struct pt_regs *re
> >
> > void __kprobes single_step_exception(struct pt_regs *regs)
> > {
> > - regs->msr &= ~(MSR_SE | MSR_BE); /* Turn off 'trace' bits */
> > + clear_single_step(regs);
> >
> > if (notify_die(DIE_SSTEP, "single_step", regs, 5,
> > 5, SIGTRAP) == NOTIFY_STOP)
> > @@ -621,10 +621,7 @@ void __kprobes single_step_exception(str
> > */
> > static void emulate_single_step(struct pt_regs *regs)
> > {
> > - if (single_stepping(regs)) {
> > - clear_single_step(regs);
> > - _exception(SIGTRAP, regs, TRAP_TRACE, 0);
> > - }
> > + single_step_exception(regs);
> > }
>
> We still need the if (single_stepping(regs)) in emulate_single_step.
> We don't want to send the process a SIGTRAP every time it gets an
> alignment interrupt. :)
>
> Paul.
Agreed, and made changes to that effect in version XXII (as seen in
patch linuxppc-dev message-id: 20100528064017.gd8...@in.ibm.com).
Thanks,
K.Prasad
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