ftrace: Convert graph filter to use hash tables

Use ftrace_hash instead of a static array of a fixed size.  This is
useful when a graph filter pattern matches to a large number of
functions.  Now hash lookup is done with preemption disabled to protect
from the hash being changed/freed.

Link: http://lkml.kernel.org/r/20170120024447.26097-3-namhyung@kernel.org

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 31 insertions, 33 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9001460291bb..afbec961eab1 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -803,51 +803,49 @@ extern void __trace_graph_return(struct trace_array *tr,
 				 unsigned long flags, int pc);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-/* TODO: make this variable */
-#define FTRACE_GRAPH_MAX_FUNCS		32
-extern int ftrace_graph_count;
-extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
-extern int ftrace_graph_notrace_count;
-extern unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS];
+extern struct ftrace_hash *ftrace_graph_hash;
+extern struct ftrace_hash *ftrace_graph_notrace_hash;
 
 static inline int ftrace_graph_addr(unsigned long addr)
 {
-	int i;
-
-	if (!ftrace_graph_count)
-		return 1;
-
-	for (i = 0; i < ftrace_graph_count; i++) {
-		if (addr == ftrace_graph_funcs[i]) {
-			/*
-			 * If no irqs are to be traced, but a set_graph_function
-			 * is set, and called by an interrupt handler, we still
-			 * want to trace it.
-			 */
-			if (in_irq())
-				trace_recursion_set(TRACE_IRQ_BIT);
-			else
-				trace_recursion_clear(TRACE_IRQ_BIT);
-			return 1;
-		}
+	int ret = 0;
+
+	preempt_disable_notrace();
+
+	if (ftrace_hash_empty(ftrace_graph_hash)) {
+		ret = 1;
+		goto out;
 	}
 
-	return 0;
+	if (ftrace_lookup_ip(ftrace_graph_hash, addr)) {
+		/*
+		 * If no irqs are to be traced, but a set_graph_function
+		 * is set, and called by an interrupt handler, we still
+		 * want to trace it.
+		 */
+		if (in_irq())
+			trace_recursion_set(TRACE_IRQ_BIT);
+		else
+			trace_recursion_clear(TRACE_IRQ_BIT);
+		ret = 1;
+	}
+
+out:
+	preempt_enable_notrace();
+	return ret;
 }
 
 static inline int ftrace_graph_notrace_addr(unsigned long addr)
 {
-	int i;
+	int ret = 0;
 
-	if (!ftrace_graph_notrace_count)
-		return 0;
+	preempt_disable_notrace();
 
-	for (i = 0; i < ftrace_graph_notrace_count; i++) {
-		if (addr == ftrace_graph_notrace_funcs[i])
-			return 1;
-	}
+	if (ftrace_lookup_ip(ftrace_graph_notrace_hash, addr))
+		ret = 1;
 
-	return 0;
+	preempt_enable_notrace();
+	return ret;
 }
 #else
 static inline int ftrace_graph_addr(unsigned long addr)