1 files changed, 90 insertions, 0 deletions
diff --git a/lib/sys_info.c b/lib/sys_info.c
index 53031e5cb98e..5bf503fd7ec1 100644
--- a/lib/sys_info.c
+++ b/lib/sys_info.c
@@ -3,10 +3,100 @@
 #include <linux/console.h>
 #include <linux/kernel.h>
 #include <linux/ftrace.h>
+#include <linux/sysctl.h>
 #include <linux/nmi.h>
 
 #include <linux/sys_info.h>
 
+struct sys_info_name {
+	unsigned long bit;
+	const char *name;
+};
+
+/*
+ * When 'si_names' gets updated,  please make sure the 'sys_info_avail'
+ * below is updated accordingly.
+ */
+static const struct sys_info_name  si_names[] = {
+	{ SYS_INFO_TASKS,		"tasks" },
+	{ SYS_INFO_MEM,			"mem" },
+	{ SYS_INFO_TIMERS,		"timers" },
+	{ SYS_INFO_LOCKS,		"locks" },
+	{ SYS_INFO_FTRACE,		"ftrace" },
+	{ SYS_INFO_ALL_CPU_BT,		"all_bt" },
+	{ SYS_INFO_BLOCKED_TASKS,	"blocked_tasks" },
+};
+
+/* Expecting string like "xxx_sys_info=tasks,mem,timers,locks,ftrace,..." */
+unsigned long sys_info_parse_param(char *str)
+{
+	unsigned long si_bits = 0;
+	char *s, *name;
+	int i;
+
+	s = str;
+	while ((name = strsep(&s, ",")) && *name) {
+		for (i = 0; i < ARRAY_SIZE(si_names); i++) {
+			if (!strcmp(name, si_names[i].name)) {
+				si_bits |= si_names[i].bit;
+				break;
+			}
+		}
+	}
+
+	return si_bits;
+}
+
+#ifdef CONFIG_SYSCTL
+
+static const char sys_info_avail[] __maybe_unused = "tasks,mem,timers,locks,ftrace,all_bt,blocked_tasks";
+
+int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
+					  void *buffer, size_t *lenp,
+					  loff_t *ppos)
+{
+	char names[sizeof(sys_info_avail) + 1];
+	struct ctl_table table;
+	unsigned long *si_bits_global;
+
+	si_bits_global = ro_table->data;
+
+	if (write) {
+		unsigned long si_bits;
+		int ret;
+
+		table = *ro_table;
+		table.data = names;
+		table.maxlen = sizeof(names);
+		ret = proc_dostring(&table, write, buffer, lenp, ppos);
+		if (ret)
+			return ret;
+
+		si_bits = sys_info_parse_param(names);
+		/* The access to the global value is not synchronized. */
+		WRITE_ONCE(*si_bits_global, si_bits);
+		return 0;
+	} else {
+		/* for 'read' operation */
+		char *delim = "";
+		int i, len = 0;
+
+		for (i = 0; i < ARRAY_SIZE(si_names); i++) {
+			if (*si_bits_global & si_names[i].bit) {
+				len += scnprintf(names + len, sizeof(names) - len,
+					"%s%s", delim, si_names[i].name);
+				delim = ",";
+			}
+		}
+
+		table = *ro_table;
+		table.data = names;
+		table.maxlen = sizeof(names);
+		return proc_dostring(&table, write, buffer, lenp, ppos);
+	}
+}
+#endif
+
 void sys_info(unsigned long si_mask)
 {
 	if (si_mask & SYS_INFO_TASKS)