ftrace: use code patching for ftrace graph tracer
Impact: more efficient code for ftrace graph tracer
This patch uses the dynamic patching, when available, to patch
the function graph code into the kernel.
This patch will ease the way for letting both function tracing
and function graph tracing run together.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 00d98c6..5f7c864 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -281,6 +281,8 @@
FTRACE_UPDATE_TRACE_FUNC = (1 << 2),
FTRACE_ENABLE_MCOUNT = (1 << 3),
FTRACE_DISABLE_MCOUNT = (1 << 4),
+ FTRACE_START_FUNC_RET = (1 << 5),
+ FTRACE_STOP_FUNC_RET = (1 << 6),
};
static int ftrace_filtered;
@@ -465,14 +467,7 @@
unsigned long ip, fl;
unsigned long ftrace_addr;
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
- if (ftrace_tracing_type == FTRACE_TYPE_ENTER)
- ftrace_addr = (unsigned long)ftrace_caller;
- else
- ftrace_addr = (unsigned long)ftrace_graph_caller;
-#else
ftrace_addr = (unsigned long)ftrace_caller;
-#endif
ip = rec->ip;
@@ -605,6 +600,11 @@
if (*command & FTRACE_UPDATE_TRACE_FUNC)
ftrace_update_ftrace_func(ftrace_trace_function);
+ if (*command & FTRACE_START_FUNC_RET)
+ ftrace_enable_ftrace_graph_caller();
+ else if (*command & FTRACE_STOP_FUNC_RET)
+ ftrace_disable_ftrace_graph_caller();
+
return 0;
}
@@ -629,10 +629,8 @@
ftrace_run_update_code(command);
}
-static void ftrace_startup(void)
+static void ftrace_startup(int command)
{
- int command = 0;
-
if (unlikely(ftrace_disabled))
return;
@@ -645,10 +643,8 @@
mutex_unlock(&ftrace_start_lock);
}
-static void ftrace_shutdown(void)
+static void ftrace_shutdown(int command)
{
- int command = 0;
-
if (unlikely(ftrace_disabled))
return;
@@ -1453,8 +1449,9 @@
static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
static inline void ftrace_startup_enable(int command) { }
-# define ftrace_startup() do { } while (0)
-# define ftrace_shutdown() do { } while (0)
+/* Keep as macros so we do not need to define the commands */
+# define ftrace_startup(command) do { } while (0)
+# define ftrace_shutdown(command) do { } while (0)
# define ftrace_startup_sysctl() do { } while (0)
# define ftrace_shutdown_sysctl() do { } while (0)
#endif /* CONFIG_DYNAMIC_FTRACE */
@@ -1585,7 +1582,7 @@
}
ret = __register_ftrace_function(ops);
- ftrace_startup();
+ ftrace_startup(0);
out:
mutex_unlock(&ftrace_sysctl_lock);
@@ -1604,7 +1601,7 @@
mutex_lock(&ftrace_sysctl_lock);
ret = __unregister_ftrace_function(ops);
- ftrace_shutdown();
+ ftrace_shutdown(0);
mutex_unlock(&ftrace_sysctl_lock);
return ret;
@@ -1751,7 +1748,7 @@
ftrace_tracing_type = FTRACE_TYPE_RETURN;
ftrace_graph_return = retfunc;
ftrace_graph_entry = entryfunc;
- ftrace_startup();
+ ftrace_startup(FTRACE_START_FUNC_RET);
out:
mutex_unlock(&ftrace_sysctl_lock);
@@ -1765,7 +1762,7 @@
atomic_dec(&ftrace_graph_active);
ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
ftrace_graph_entry = (trace_func_graph_ent_t)ftrace_stub;
- ftrace_shutdown();
+ ftrace_shutdown(FTRACE_STOP_FUNC_RET);
/* Restore normal tracing type */
ftrace_tracing_type = FTRACE_TYPE_ENTER;
