ftrace: Sort the mcount records on each page

Sort records by ip locations of the ftrace mcount calls on each of the
set of pages in the function list. This helps in localizing cache
usuage when updating the function locations, as well as gives us
the ability to quickly find an ip location in the list.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/ftrace.c

@@ -27,6 +27,7 @@
 #include <linux/sysctl.h>
 #include <linux/slab.h>
 #include <linux/ctype.h>
+#include <linux/sort.h>
 #include <linux/list.h>
 #include <linux/hash.h>
 #include <linux/rcupdate.h>
@@ -3575,6 +3576,29 @@ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
 	return 0;
 }
 
+static void ftrace_swap_recs(void *a, void *b, int size)
+{
+	struct dyn_ftrace *reca = a;
+	struct dyn_ftrace *recb = b;
+	struct dyn_ftrace t;
+
+	t = *reca;
+	*reca = *recb;
+	*recb = t;
+}
+
+static int ftrace_cmp_recs(const void *a, const void *b)
+{
+	const struct dyn_ftrace *reca = a;
+	const struct dyn_ftrace *recb = b;
+
+	if (reca->ip > recb->ip)
+		return 1;
+	if (reca->ip < recb->ip)
+		return -1;
+	return 0;
+}
+
 static int ftrace_process_locs(struct module *mod,
 			       unsigned long *start,
 			       unsigned long *end)
@@ -3638,6 +3662,11 @@ static int ftrace_process_locs(struct module *mod,
 	/* These new locations need to be initialized */
 	ftrace_new_pgs = pg;
 
+	/* Make each individual set of pages sorted by ips */
+	for (; pg; pg = pg->next)
+		sort(pg->records, pg->index, sizeof(struct dyn_ftrace),
+		     ftrace_cmp_recs, ftrace_swap_recs);
+
 	/*
 	 * We only need to disable interrupts on start up
 	 * because we are modifying code that an interrupt