tracing: add support for userspace stacktraces in tracing/iter_ctrl

Impact: add new (default-off) tracing visualization feature

Usage example:

 mount -t debugfs nodev /sys/kernel/debug
 cd /sys/kernel/debug/tracing
 echo userstacktrace >iter_ctrl
 echo sched_switch >current_tracer
 echo 1 >tracing_enabled
 .... run application ...
 echo 0 >tracing_enabled

Then read one of 'trace','latency_trace','trace_pipe'.

To get the best output you can compile your userspace programs with
frame pointers (at least glibc + the app you are tracing).

Signed-off-by: Török Edwin <edwintorok@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 9 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2cb12fd98f6b..17bb4c830b01 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -26,6 +26,7 @@ enum trace_type {
         TRACE_BOOT_CALL,
         TRACE_BOOT_RET,
         TRACE_FN_RET,
+        TRACE_USER_STACK,
 
         __TRACE_LAST_TYPE
 };
@@ -42,6 +43,7 @@ struct trace_entry {
         unsigned char           flags;
         unsigned char           preempt_count;
         int                     pid;
+        int                     tgid;
 };
 
 /*
@@ -99,6 +101,11 @@ struct stack_entry {
         unsigned long           caller[FTRACE_STACK_ENTRIES];
 };
 
+struct userstack_entry {
+        struct trace_entry      ent;
+        unsigned long           caller[FTRACE_STACK_ENTRIES];
+};
+
 /*
  * ftrace_printk entry:
  */
@@ -240,6 +247,7 @@ extern void __ftrace_bad_type(void);
                 IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);        \
                 IF_ASSIGN(var, ent, struct trace_field_cont, TRACE_CONT); \
                 IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);   \
+                IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
                 IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);   \
                 IF_ASSIGN(var, ent, struct special_entry, 0);           \
                 IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,          \
@@ -500,6 +508,7 @@ enum trace_iterator_flags {
         TRACE_ITER_PREEMPTONLY          = 0x800,
         TRACE_ITER_BRANCH               = 0x1000,
         TRACE_ITER_ANNOTATE             = 0x2000,
+        TRACE_ITER_USERSTACKTRACE       = 0x4000
 };
 
 /*