tracing: add __print_symbolic to trace events
This patch adds __print_symbolic which is similar to __print_flags but
works for an enumeration type instead. That is, there is only a one to one
mapping between the values and the symbols. When a match is made, then
it is printed, otherwise the hex value is outputed.
[ Impact: add interface for showing symbol names in events ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 4b58cf1..bbf40f6 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -20,6 +20,9 @@
unsigned long flags,
const struct trace_print_flags *flag_array);
+const char *ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
+ const struct trace_print_flags *symbol_array);
+
/*
* The trace entry - the most basic unit of tracing. This is what
* is printed in the end as a single line in the trace output, such as:
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 22c9471..87fc227 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -130,6 +130,14 @@
ftrace_print_flags_seq(p, delim, flag, flags); \
})
+#undef __print_symbolic
+#define __print_symbolic(value, symbol_array...) \
+ ({ \
+ static const struct trace_print_flags symbols[] = \
+ { symbol_array, { -1, NULL }}; \
+ ftrace_print_symbols_seq(p, value, symbols); \
+ })
+
#undef TRACE_EVENT
#define TRACE_EVENT(call, proto, args, tstruct, assign, print) \
enum print_line_t \
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index a4840c2..c12d95d 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -251,6 +251,31 @@
return p->buffer;
}
+const char *
+ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
+ const struct trace_print_flags *symbol_array)
+{
+ int i;
+
+ trace_seq_init(p);
+
+ for (i = 0; symbol_array[i].name; i++) {
+
+ if (val != symbol_array[i].mask)
+ continue;
+
+ trace_seq_puts(p, symbol_array[i].name);
+ break;
+ }
+
+ if (!p->len)
+ trace_seq_printf(p, "0x%lx", val);
+
+ trace_seq_putc(p, 0);
+
+ return p->buffer;
+}
+
#ifdef CONFIG_KRETPROBES
static inline const char *kretprobed(const char *name)
{
