[IA64] kprobe: make kreturn probe handler stack unwind correct

Restore regs->ccr_iip before kreturn probe handler runs. In this way, if
probe handler does unwind, unwind can correctly get the stack trace.

Fixes: http://sourceware.org/bugzilla/show_bug.cgi?id=5051

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 90518e43aba0..fc4d2676264f 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -435,6 +435,23 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
                         /* another task is sharing our hash bucket */
                         continue;
 
+                orig_ret_address = (unsigned long)ri->ret_addr;
+                if (orig_ret_address != trampoline_address)
+                        /*
+                         * This is the real return address. Any other
+                         * instances associated with this task are for
+                         * other calls deeper on the call stack
+                         */
+                        break;
+        }
+
+        regs->cr_iip = orig_ret_address;
+
+        hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+                if (ri->task != current)
+                        /* another task is sharing our hash bucket */
+                        continue;
+
                 if (ri->rp && ri->rp->handler)
                         ri->rp->handler(ri, regs);
 
@@ -452,8 +469,6 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 
         kretprobe_assert(ri, orig_ret_address, trampoline_address);
 
-        regs->cr_iip = orig_ret_address;
-
         reset_current_kprobe();
         spin_unlock_irqrestore(&kretprobe_lock, flags);
         preempt_enable_no_resched();