tracing: add saved_cmdlines file to show cached task comms
Export the cached task comms to userspace. This allows user apps to translate
the pids from a trace into their respective task command lines.
[ Impact: let userspace apps reading binary buffer know comm's of pids ]
Signed-off-by: Avadh Patel <avadh4all@gmail.com>
[ added error checking and use of buf pointer to index file_buf ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2d69b26..031c46f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2422,6 +2422,56 @@
};
static ssize_t
+tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char *buf_comm;
+ char *file_buf;
+ char *buf;
+ int len = 0;
+ int pid;
+ int i;
+
+ file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);
+ if (!file_buf)
+ return -ENOMEM;
+
+ buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);
+ if (!buf_comm) {
+ kfree(file_buf);
+ return -ENOMEM;
+ }
+
+ buf = file_buf;
+
+ for (i = 0; i < SAVED_CMDLINES; i++) {
+ int r;
+
+ pid = map_cmdline_to_pid[i];
+ if (pid == -1 || pid == NO_CMDLINE_MAP)
+ continue;
+
+ trace_find_cmdline(pid, buf_comm);
+ r = sprintf(buf, "%d %s\n", pid, buf_comm);
+ buf += r;
+ len += r;
+ }
+
+ len = simple_read_from_buffer(ubuf, cnt, ppos,
+ file_buf, len);
+
+ kfree(file_buf);
+ kfree(buf_comm);
+
+ return len;
+}
+
+static const struct file_operations tracing_saved_cmdlines_fops = {
+ .open = tracing_open_generic,
+ .read = tracing_saved_cmdlines_read,
+};
+
+static ssize_t
tracing_ctrl_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
@@ -3973,6 +4023,9 @@
trace_create_file("trace_marker", 0220, d_tracer,
NULL, &tracing_mark_fops);
+ trace_create_file("saved_cmdlines", 0444, d_tracer,
+ NULL, &tracing_saved_cmdlines_fops);
+
#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt, &tracing_dyn_info_fops);