powerpc/kprobes: Emulate instructions on kprobe handler re-entry

On kprobe handler re-entry, try to emulate the instruction rather than single
stepping always.

Acked-by: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index ed5a917c2edd6d535414842a193a733990c57dc4..b71922618ed25f1d9e6fc8b257cb6554de84e2b1 100644 (file)
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -277,6 +277,14 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
                        kprobes_inc_nmissed_count(p);
                        prepare_singlestep(p, regs);
                        kcb->kprobe_status = KPROBE_REENTER;
+                       if (p->ainsn.boostable >= 0) {
+                               ret = try_to_emulate(p, regs);
+
+                               if (ret > 0) {
+                                       restore_previous_kprobe(kcb);
+                                       return 1;
+                               }
+                       }
                        return 1;
                } else {
                        if (*addr != BREAKPOINT_INSTRUCTION) {