microblaze: ftrace: Add dynamic function graph tracer

This patch add support for dynamic function graph tracer.

There is one my expactation that I can do flush_icache after
all code modification. On microblaze is this safer than do
flush for every entry. For icache is used name flush but
correct should be invalidation - this will be fix in upcomming
new cache implementaion and WB support.

Signed-off-by: Michal Simek <monstr@monstr.eu>

2 files changed, 34 insertions, 0 deletions

diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c
index 0952a8b52c35..388b31ca65a1 100644
--- a/arch/microblaze/kernel/ftrace.c
+++ b/arch/microblaze/kernel/ftrace.c
@@ -206,4 +206,32 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
         return ret;
 }
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+unsigned int old_jump; /* saving place for jump instruction */
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+        unsigned int ret;
+        unsigned long ip = (unsigned long)(&ftrace_call_graph);
+
+        old_jump = *(unsigned int *)ip; /* save jump over instruction */
+        ret = ftrace_modify_code(ip, MICROBLAZE_NOP);
+        flush_icache();
+
+        pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump);
+        return ret;
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+        unsigned int ret;
+        unsigned long ip = (unsigned long)(&ftrace_call_graph);
+
+        ret = ftrace_modify_code(ip, old_jump);
+        flush_icache();
+
+        pr_debug("%s\n", __func__);
+        return ret;
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 #endif /* CONFIG_DYNAMIC_FTRACE */
diff --git a/arch/microblaze/kernel/mcount.S b/arch/microblaze/kernel/mcount.S
index 84a19458c74d..e7eaa7a8cbd3 100644
--- a/arch/microblaze/kernel/mcount.S
+++ b/arch/microblaze/kernel/mcount.S
@@ -97,6 +97,7 @@ ENTRY(ftrace_caller)
         nop;
         /* MS: HAVE_FUNCTION_TRACE_MCOUNT_TEST end of checking */
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#ifndef CONFIG_DYNAMIC_FTRACE
         lwi     r5, r0, ftrace_graph_return;
         addik   r6, r0, ftrace_stub; /* asm implementation */
         cmpu    r5, r5, r6; /* ftrace_graph_return != ftrace_stub */
@@ -108,6 +109,11 @@ ENTRY(ftrace_caller)
         cmpu    r5, r5, r6; /* ftrace_graph_entry != ftrace_graph_entry_stub */
         beqid   r5, end_graph_tracer;
         nop;
+#else /* CONFIG_DYNAMIC_FTRACE */
+NOALIGN_ENTRY(ftrace_call_graph)
+        /* MS: jump over graph function - replaced from C code */
+        bri     end_graph_tracer
+#endif /* CONFIG_DYNAMIC_FTRACE */
         addik   r5, r1, 120; /* MS: load parent addr */
         addik   r6, r15, 0; /* MS: load current function addr */
         bralid  r15, prepare_ftrace_return;