1 files changed, 78 insertions, 14 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3dc7999594e1..829b2bee24e8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3300,20 +3300,84 @@ static const struct file_operations tracing_iter_fops = {
 
 static const char readme_msg[] =
         "tracing mini-HOWTO:\n\n"
-        "# mount -t debugfs nodev /sys/kernel/debug\n\n"
-        "# cat /sys/kernel/debug/tracing/available_tracers\n"
-        "wakeup wakeup_rt preemptirqsoff preemptoff irqsoff function nop\n\n"
-        "# cat /sys/kernel/debug/tracing/current_tracer\n"
-        "nop\n"
-        "# echo wakeup > /sys/kernel/debug/tracing/current_tracer\n"
-        "# cat /sys/kernel/debug/tracing/current_tracer\n"
-        "wakeup\n"
-        "# cat /sys/kernel/debug/tracing/trace_options\n"
-        "noprint-parent nosym-offset nosym-addr noverbose\n"
-        "# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
-        "# echo 1 > /sys/kernel/debug/tracing/tracing_on\n"
-        "# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
-        "# echo 0 > /sys/kernel/debug/tracing/tracing_on\n"
+        "# echo 0 > tracing_on : quick way to disable tracing\n"
+        "# echo 1 > tracing_on : quick way to re-enable tracing\n\n"
+        " Important files:\n"
+        "  trace\t\t\t- The static contents of the buffer\n"
+        "\t\t\t  To clear the buffer write into this file: echo > trace\n"
+        "  trace_pipe\t\t- A consuming read to see the contents of the buffer\n"
+        "  current_tracer\t- function and latency tracers\n"
+        "  available_tracers\t- list of configured tracers for current_tracer\n"
+        "  buffer_size_kb\t- view and modify size of per cpu buffer\n"
+        "  buffer_total_size_kb  - view total size of all cpu buffers\n\n"
+        "  trace_clock\t\t-change the clock used to order events\n"
+        "       local:   Per cpu clock but may not be synced across CPUs\n"
+        "      global:   Synced across CPUs but slows tracing down.\n"
+        "     counter:   Not a clock, but just an increment\n"
+        "      uptime:   Jiffy counter from time of boot\n"
+        "        perf:   Same clock that perf events use\n"
+#ifdef CONFIG_X86_64
+        "     x86-tsc:   TSC cycle counter\n"
+#endif
+        "\n  trace_marker\t\t- Writes into this file writes into the kernel buffer\n"
+        "  tracing_cpumask\t- Limit which CPUs to trace\n"
+        "  instances\t\t- Make sub-buffers with: mkdir instances/foo\n"
+        "\t\t\t  Remove sub-buffer with rmdir\n"
+        "  trace_options\t\t- Set format or modify how tracing happens\n"
+        "\t\t\t  Disable an option by adding a suffix 'no' to the option name\n"
+#ifdef CONFIG_DYNAMIC_FTRACE
+        "\n  available_filter_functions - list of functions that can be filtered on\n"
+        "  set_ftrace_filter\t- echo function name in here to only trace these functions\n"
+        "            accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+        "            modules: Can select a group via module\n"
+        "             Format: :mod:<module-name>\n"
+        "             example: echo :mod:ext3 > set_ftrace_filter\n"
+        "            triggers: a command to perform when function is hit\n"
+        "              Format: <function>:<trigger>[:count]\n"
+        "             trigger: traceon, traceoff\n"
+        "                      enable_event:<system>:<event>\n"
+        "                      disable_event:<system>:<event>\n"
+#ifdef CONFIG_STACKTRACE
+        "                      stacktrace\n"
+#endif
+#ifdef CONFIG_TRACER_SNAPSHOT
+        "                      snapshot\n"
+#endif
+        "             example: echo do_fault:traceoff > set_ftrace_filter\n"
+        "                      echo do_trap:traceoff:3 > set_ftrace_filter\n"
+        "             The first one will disable tracing every time do_fault is hit\n"
+        "             The second will disable tracing at most 3 times when do_trap is hit\n"
+        "               The first time do trap is hit and it disables tracing, the counter\n"
+        "               will decrement to 2. If tracing is already disabled, the counter\n"
+        "               will not decrement. It only decrements when the trigger did work\n"
+        "             To remove trigger without count:\n"
+        "               echo '!<function>:<trigger> > set_ftrace_filter\n"
+        "             To remove trigger with a count:\n"
+        "               echo '!<function>:<trigger>:0 > set_ftrace_filter\n"
+        "  set_ftrace_notrace\t- echo function name in here to never trace.\n"
+        "            accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+        "            modules: Can select a group via module command :mod:\n"
+        "            Does not accept triggers\n"
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#ifdef CONFIG_FUNCTION_TRACER
+        "  set_ftrace_pid\t- Write pid(s) to only function trace those pids (function)\n"
+#endif
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        "  set_graph_function\t- Trace the nested calls of a function (function_graph)\n"
+        "  max_graph_depth\t- Trace a limited depth of nested calls (0 is unlimited)\n"
+#endif
+#ifdef CONFIG_TRACER_SNAPSHOT
+        "\n  snapshot\t\t- Like 'trace' but shows the content of the static snapshot buffer\n"
+        "\t\t\t  Read the contents for more information\n"
+#endif
+#ifdef CONFIG_STACKTRACE
+        "  stack_trace\t\t- Shows the max stack trace when active\n"
+        "  stack_max_size\t- Shows current max stack size that was traced\n"
+        "\t\t\t  Write into this file to reset the max size (trigger a new trace)\n"
+#ifdef CONFIG_DYNAMIC_FTRACE
+        "  stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace traces\n"
+#endif
+#endif /* CONFIG_STACKTRACE */
 ;
 
 static ssize_t