[RFC PATCH v2 20/31] function_graph: Add a new exit handler with parent_ip and ftrace_regs

["Masami Hiramatsu (Google)" <mhiramat@kernel.org>]

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Add a new return handler to fgraph_ops as 'retregfunc'  which takes
parent_ip and ftrace_regs instead of ftrace_graph_ret. This handler
is available only if the arch support CONFIG_HAVE_FUNCTION_GRAPH_FREGS.
Note that the 'retfunc' and 'reregfunc' are mutual exclusive.
You can set only one of them.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 arch/x86/include/asm/ftrace.h |    2 +
 include/linux/ftrace.h        |   10 +++++-
 kernel/trace/Kconfig          |    5 ++-
 kernel/trace/fgraph.c         |   74 +++++++++++++++++++++++++++--------------
 4 files changed, 63 insertions(+), 28 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index fc60974a1d89..4701d009c215 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -72,6 +72,8 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
 	override_function_with_return(&(fregs)->regs)
 #define ftrace_regs_query_register_offset(name) \
 	regs_query_register_offset(name)
+#define ftrace_regs_get_frame_pointer(fregs) \
+	frame_pointer(&(fregs)->regs)
 
 struct ftrace_ops;
 #define ftrace_graph_func ftrace_graph_func
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index c91b234949d5..8efccd911d41 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -43,7 +43,9 @@ struct dyn_ftrace;
 
 char *arch_ftrace_match_adjust(char *str, const char *search);
 
-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+unsigned long ftrace_return_to_handler(struct ftrace_regs *fregs);
+#elif defined(CONFIG_HAVE_FUNCTION_GRAPH_RETVAL)
 struct fgraph_ret_regs;
 unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs);
 #else
@@ -156,6 +158,7 @@ struct ftrace_regs {
 #define ftrace_regs_set_instruction_pointer(fregs, ip) do { } while (0)
 #endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
 
+
 static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs)
 {
 	if (!fregs)
@@ -1066,6 +1069,10 @@ typedef int (*trace_func_graph_regs_ent_t)(unsigned long func,
 					   unsigned long parent_ip,
 					   struct ftrace_regs *fregs,
 					   struct fgraph_ops *); /* entry w/ regs */
+typedef void (*trace_func_graph_regs_ret_t)(unsigned long func,
+					    unsigned long parent_ip,
+					    struct ftrace_regs *,
+					    struct fgraph_ops *); /* return w/ regs */
 
 extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
 
@@ -1075,6 +1082,7 @@ struct fgraph_ops {
 	trace_func_graph_ent_t		entryfunc;
 	trace_func_graph_ret_t		retfunc;
 	trace_func_graph_regs_ent_t	entryregfunc;
+	trace_func_graph_regs_ret_t	retregfunc;
 	struct ftrace_ops		ops; /* for the hash lists */
 	void				*private;
 	int				idx;
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 61c541c36596..308b3bec01b1 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -34,6 +34,9 @@ config HAVE_FUNCTION_GRAPH_TRACER
 config HAVE_FUNCTION_GRAPH_RETVAL
 	bool
 
+config HAVE_FUNCTION_GRAPH_FREGS
+	bool
+
 config HAVE_DYNAMIC_FTRACE
 	bool
 	help
@@ -232,7 +235,7 @@ config FUNCTION_GRAPH_TRACER
 
 config FUNCTION_GRAPH_RETVAL
 	bool "Kernel Function Graph Return Value"
-	depends on HAVE_FUNCTION_GRAPH_RETVAL
+	depends on HAVE_FUNCTION_GRAPH_RETVAL || HAVE_FUNCTION_GRAPH_FREGS
 	depends on FUNCTION_GRAPH_TRACER
 	default n
 	help
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 6567b18c6c54..cf240914ef9b 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -623,8 +623,7 @@ int function_graph_enter_regs(unsigned long ret, unsigned long func,
 
 /* Retrieve a function return address to the trace stack on thread info.*/
 static struct ftrace_ret_stack *
-ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
-			unsigned long frame_pointer)
+ftrace_pop_return_trace(unsigned long *ret, unsigned long frame_pointer)
 {
 	struct ftrace_ret_stack *ret_stack;
 	int index;
@@ -669,10 +668,6 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
 #endif
 
 	*ret = ret_stack->ret;
-	trace->func = ret_stack->func;
-	trace->calltime = ret_stack->calltime;
-	trace->overrun = atomic_read(&current->trace_overrun);
-	trace->depth = current->curr_ret_depth;
 	/*
 	 * We still want to trace interrupts coming in if
 	 * max_depth is set to 1. Make sure the decrement is
@@ -711,22 +706,43 @@ static struct notifier_block ftrace_suspend_notifier = {
 /* fgraph_ret_regs is not defined without CONFIG_FUNCTION_GRAPH_RETVAL */
 struct fgraph_ret_regs;
 
+static void fgraph_call_retfunc(struct ftrace_regs *fregs,
+				struct fgraph_ret_regs *ret_regs,
+				struct ftrace_ret_stack *ret_stack,
+				struct fgraph_ops *gops)
+{
+	struct ftrace_graph_ret trace;
+
+	trace.func = ret_stack->func;
+	trace.calltime = ret_stack->calltime;
+	trace.overrun = atomic_read(&current->trace_overrun);
+	trace.depth = current->curr_ret_depth;
+	trace.rettime = trace_clock_local();
+#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
+	if (fregs)
+		trace.retval = ftrace_regs_return_value(fregs);
+	else
+		trace.retval = fgraph_ret_regs_return_value(ret_regs);
+#endif
+	gops->retfunc(&trace, gops);
+}
+
 /*
  * Send the trace to the ring-buffer.
  * @return the original return address.
  */
-static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs,
+static unsigned long __ftrace_return_to_handler(struct ftrace_regs *fregs,
+						struct fgraph_ret_regs *ret_regs,
 						unsigned long frame_pointer)
 {
 	struct ftrace_ret_stack *ret_stack;
-	struct ftrace_graph_ret trace;
-	unsigned long ret;
+	struct fgraph_ops *gops;
 	int curr_ret_stack;
+	unsigned long ret;
 	int stop_at;
 	int index;
-	int idx;
 
-	ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer);
+	ret_stack = ftrace_pop_return_trace(&ret, frame_pointer);
 
 	if (unlikely(!ret_stack)) {
 		ftrace_graph_stop();
@@ -735,11 +751,6 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
 		return (unsigned long)panic;
 	}
 
-	trace.rettime = trace_clock_local();
-#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
-	trace.retval = fgraph_ret_regs_return_value(ret_regs);
-#endif
-
 	curr_ret_stack = current->curr_ret_stack;
 	index = get_ret_stack_index(current, curr_ret_stack - 1);
 
@@ -752,8 +763,11 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
 		val = current->ret_stack[curr_ret_stack - 1];
 		switch (__get_type(val)) {
 		case FGRAPH_TYPE_ARRAY:
-			idx = __get_array(val);
-			fgraph_array[idx]->retfunc(&trace, fgraph_array[idx]);
+			gops = fgraph_array[__get_array(val)];
+			if (gops->retregfunc)
+				gops->retregfunc(ret_stack->func, ret, fregs, gops);
+			else
+				fgraph_call_retfunc(fregs, ret_regs, ret_stack, gops);
 			curr_ret_stack -= __get_index(val);
 			break;
 		case FGRAPH_TYPE_RESERVED:
@@ -777,20 +791,22 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
 	return ret;
 }
 
-/*
- * After all architecures have selected HAVE_FUNCTION_GRAPH_RETVAL, we can
- * leave only ftrace_return_to_handler(ret_regs).
- */
-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+unsigned long ftrace_return_to_handler(struct ftrace_regs *fregs)
+{
+	return __ftrace_return_to_handler(fregs, NULL,
+				ftrace_regs_get_frame_pointer(fregs));
+}
+#elif defined(CONFIG_HAVE_FUNCTION_GRAPH_RETVAL)
 unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs)
 {
-	return __ftrace_return_to_handler(ret_regs,
+	return __ftrace_return_to_handler(NULL, ret_regs,
 				fgraph_ret_regs_frame_pointer(ret_regs));
 }
 #else
 unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
 {
-	return __ftrace_return_to_handler(NULL, frame_pointer);
+	return __ftrace_return_to_handler(NULL, NULL, frame_pointer);
 }
 #endif
 
@@ -1131,9 +1147,15 @@ int register_ftrace_graph(struct fgraph_ops *gops)
 	int ret = 0;
 	int i;
 
-	if (gops->entryfunc && gops->entryregfunc)
+	if ((gops->entryfunc && gops->entryregfunc) ||
+	    (gops->retfunc && gops->retregfunc))
 		return -EINVAL;
 
+#ifndef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+	if (gops->retregfunc)
+		return -EOPNOTSUPP;
+#endif
+
 	mutex_lock(&ftrace_lock);
 
 	if (!gops->ops.func) {