[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>

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 90518e43aba0703ad7e0befa9a793a8b746b7bef..fc4d2676264f363d766ce4d9b6c5f76176fd4cb4 100644 (file)
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -430,6 +430,23 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
         *       real return address, and all the rest will point to
         *       kretprobe_trampoline
         */
+       hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+               if (ri->task != current)
+                       /* 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 */
@@ -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();