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>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2cb12fd..17bb4c8 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -26,6 +26,7 @@
TRACE_BOOT_CALL,
TRACE_BOOT_RET,
TRACE_FN_RET,
+ TRACE_USER_STACK,
__TRACE_LAST_TYPE
};
@@ -42,6 +43,7 @@
unsigned char flags;
unsigned char preempt_count;
int pid;
+ int tgid;
};
/*
@@ -99,6 +101,11 @@
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 @@
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 @@
TRACE_ITER_PREEMPTONLY = 0x800,
TRACE_ITER_BRANCH = 0x1000,
TRACE_ITER_ANNOTATE = 0x2000,
+ TRACE_ITER_USERSTACKTRACE = 0x4000
};
/*