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[PATCH] kprobe: make kreturn probe handler stack unwind correct
- From: Shaohua Li <shaohua dot li at intel dot com>
- To: ia64 <linux-ia64 at vger dot kernel dot org>, systemtap at sources dot redhat dot com
- Cc: "Luck, Tony" <tony dot luck at intel dot com>, "Mao, Bibo" <bibo dot mao at intel dot com>
- Date: Tue, 13 Nov 2007 14:55:20 +0800
- Subject: [PATCH] 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.
http://sourceware.org/bugzilla/show_bug.cgi?id=5051
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Index: linux/arch/ia64/kernel/kprobes.c
===================================================================
--- linux.orig/arch/ia64/kernel/kprobes.c 2007-10-17 10:33:45.000000000 +0800
+++ linux/arch/ia64/kernel/kprobes.c 2007-11-13 14:39:50.000000000 +0800
@@ -435,6 +435,23 @@ int __kprobes trampoline_probe_handler(s
/* 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(s
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();