1 files changed, 15 insertions, 58 deletions

diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index e66af6d265e8..44d4d8eb3c85 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -510,79 +510,36 @@ int ftrace_disable_ftrace_graph_caller(void)
 }
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
-#ifdef CONFIG_PPC64
-extern void mod_return_to_handler(void);
-#endif
-
 /*
  * Hook the return address and push it in the stack of return addrs
- * in current thread info.
+ * in current thread info. Return the address we want to divert to.
  */
-void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
 {
-        unsigned long old;
-        int faulted;
         struct ftrace_graph_ent trace;
-        unsigned long return_hooker = (unsigned long)&return_to_handler;
+        unsigned long return_hooker;
 
         if (unlikely(ftrace_graph_is_dead()))
-                return;
+                goto out;
 
         if (unlikely(atomic_read(&current->tracing_graph_pause)))
-                return;
-
-#ifdef CONFIG_PPC64
-        /* non core kernel code needs to save and restore the TOC */
-        if (REGION_ID(self_addr) != KERNEL_REGION_ID)
-                return_hooker = (unsigned long)&mod_return_to_handler;
-#endif
-
-        return_hooker = ppc_function_entry((void *)return_hooker);
+                goto out;
 
-        /*
-         * Protect against fault, even if it shouldn't
-         * happen. This tool is too much intrusive to
-         * ignore such a protection.
-         */
-        asm volatile(
-                "1: " PPC_LL "%[old], 0(%[parent])\n"
-                "2: " PPC_STL "%[return_hooker], 0(%[parent])\n"
-                "   li %[faulted], 0\n"
-                "3:\n"
-
-                ".section .fixup, \"ax\"\n"
-                "4: li %[faulted], 1\n"
-                "   b 3b\n"
-                ".previous\n"
-
-                ".section __ex_table,\"a\"\n"
-                        PPC_LONG_ALIGN "\n"
-                        PPC_LONG "1b,4b\n"
-                        PPC_LONG "2b,4b\n"
-                ".previous"
-
-                : [old] "=&r" (old), [faulted] "=r" (faulted)
-                : [parent] "r" (parent), [return_hooker] "r" (return_hooker)
-                : "memory"
-        );
-
-        if (unlikely(faulted)) {
-                ftrace_graph_stop();
-                WARN_ON(1);
-                return;
-        }
+        return_hooker = ppc_function_entry(return_to_handler);
 
-        trace.func = self_addr;
+        trace.func = ip;
         trace.depth = current->curr_ret_stack + 1;
 
         /* Only trace if the calling function expects to */
-        if (!ftrace_graph_entry(&trace)) {
-                *parent = old;
-                return;
-        }
+        if (!ftrace_graph_entry(&trace))
+                goto out;
+
+        if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
+                goto out;
 
-        if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY)
-                *parent = old;
+        parent = return_hooker;
+out:
+        return parent;
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */