microblaze: ftrace: add function graph support

[pandora-kernel.git] / arch / microblaze / kernel / ftrace.c

diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c
index c1889b1..0952a8b 100644 (file)
--- a/arch/microblaze/kernel/ftrace.c
+++ b/arch/microblaze/kernel/ftrace.c
@@ -14,6 +14,64 @@
 #include <asm/cacheflush.h>
 #include <linux/ftrace.h>
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+{
+       unsigned long old;
+       int faulted, err;
+       struct ftrace_graph_ent trace;
+       unsigned long return_hooker = (unsigned long)
+                               &return_to_handler;
+
+       if (unlikely(atomic_read(&current->tracing_graph_pause)))
+               return;
+
+       /*
+        * Protect against fault, even if it shouldn't
+        * happen. This tool is too much intrusive to
+        * ignore such a protection.
+        */
+       asm volatile("  1:      lwi     %0, %2, 0;              \
+                       2:      swi     %3, %2, 0;              \
+                               addik   %1, r0, 0;              \
+                       3:                                      \
+                               .section .fixup, \"ax\";        \
+                       4:      brid    3b;                     \
+                               addik   %1, r0, 1;              \
+                               .previous;                      \
+                               .section __ex_table,\"a\";      \
+                               .word   1b,4b;                  \
+                               .word   2b,4b;                  \
+                               .previous;"                     \
+                       : "=&r" (old), "=r" (faulted)
+                       : "r" (parent), "r" (return_hooker)
+       );
+
+       if (unlikely(faulted)) {
+               ftrace_graph_stop();
+               WARN_ON(1);
+               return;
+       }
+
+       err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
+       if (err == -EBUSY) {
+               *parent = old;
+               return;
+       }
+
+       trace.func = self_addr;
+       /* Only trace if the calling function expects to */
+       if (!ftrace_graph_entry(&trace)) {
+               current->curr_ret_stack--;
+               *parent = old;
+       }
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
 #ifdef CONFIG_DYNAMIC_FTRACE
 /* save value to addr - it is save to do it in asm */
 static int ftrace_modify_code(unsigned long addr, unsigned int value)