runtime backtracing: port commit #2e7f8442 to uprobes1

    * runtime/uprobes/uprobes.c (uprobe_get_pc): new function

1 files changed, 38 insertions, 0 deletions

diff --git a/runtime/uprobes/uprobes.c b/runtime/uprobes/uprobes.c
index 60c84509..cdb98707 100644
--- a/runtime/uprobes/uprobes.c
+++ b/runtime/uprobes/uprobes.c
@@ -2596,6 +2596,44 @@ static void uretprobe_set_trampoline(struct uprobe_process *uproc,
 	}
 }
 
+unsigned long uprobe_get_pc(struct uretprobe_instance *ri, unsigned long pc,
+			unsigned long sp)
+{
+        struct uretprobe *rp;
+        struct uprobe_kimg *uk;
+        struct uprobe_process *uproc;
+        unsigned long trampoline_addr;
+        struct hlist_node *r;
+        struct uretprobe_instance *ret_inst;
+
+        if (!ri)
+                return 0;
+        rp = ri->rp;
+        uk = (struct uprobe_kimg *)rp->u.kdata;
+        if (!uk)
+                return 0;
+        uproc = uk->ppt->uproc;
+        if (IS_ERR(uproc->uretprobe_trampoline_addr))
+          return pc;
+        trampoline_addr = (unsigned long)uproc->uretprobe_trampoline_addr;
+        if (pc != trampoline_addr)
+                return pc;
+        r = &ri->hlist;
+        hlist_for_each_entry_from(ret_inst, r, hlist) {
+                if (ret_inst->ret_addr == trampoline_addr)
+                        continue;
+                /* First handler with a stack pointer lower than the
+                   address (or equal) must be the one. */
+                if (ret_inst->sp == sp || compare_stack_ptrs(ret_inst->sp, sp))
+                        return ret_inst->ret_addr;
+        }
+        printk(KERN_ERR "Original return address for trampoline not found at "
+               "0x%lx pid/tgid=%d/%d\n", sp, current->pid, current->tgid);
+        return 0;
+}
+
+EXPORT_SYMBOL_GPL(uprobe_get_pc);
+
 #else	/* ! CONFIG_URETPROBES */
 
 static void uretprobe_handle_entry(struct uprobe *u, struct pt_regs *regs,