tracing: expose current->comm to [ku]probe events
ftrace is very quick to give up on saving the task command line (see
`trace_save_cmdline()`). The workaround for events which really care
about the command line is to explicitly assign it as part of the entry.
However, this doesn't work for kprobe events, as there's no
straightforward way to get access to current->comm. Add a kprobe/uprobe
event variable $comm which provides exactly that.
Link: http://lkml.kernel.org/r/f59b472033b943a370f5f48d0af37698f409108f.1465435894.git.osandov@fb.com
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index f6398db..45400ca 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -102,6 +102,7 @@
FETCH_MTD_reg = 0,
FETCH_MTD_stack,
FETCH_MTD_retval,
+ FETCH_MTD_comm,
FETCH_MTD_memory,
FETCH_MTD_symbol,
FETCH_MTD_deref,
@@ -183,6 +184,14 @@
#define fetch_bitfield_string NULL
#define fetch_bitfield_string_size NULL
+/* comm only makes sense as a string */
+#define fetch_comm_u8 NULL
+#define fetch_comm_u16 NULL
+#define fetch_comm_u32 NULL
+#define fetch_comm_u64 NULL
+DECLARE_FETCH_FUNC(comm, string);
+DECLARE_FETCH_FUNC(comm, string_size);
+
/*
* Define macro for basic types - we don't need to define s* types, because
* we have to care only about bitwidth at recording time.
@@ -213,6 +222,7 @@
ASSIGN_FETCH_FUNC(reg, ftype), \
ASSIGN_FETCH_FUNC(stack, ftype), \
ASSIGN_FETCH_FUNC(retval, ftype), \
+ASSIGN_FETCH_FUNC(comm, ftype), \
ASSIGN_FETCH_FUNC(memory, ftype), \
ASSIGN_FETCH_FUNC(symbol, ftype), \
ASSIGN_FETCH_FUNC(deref, ftype), \