tracing: have event_trace_printk use static tracer

Impact: speed up on event tracing

The event_trace_printk is currently a wrapper function that calls
trace_vprintk. Because it uses a variable for the fmt it misses out
on the optimization of using the binary printk.

This patch makes event_trace_printk into a macro wrapper to use the
fmt as the same as the trace_printks.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index cede1ab49d0..35cfa7bbaf3 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -773,4 +773,21 @@ void event_trace_printk(unsigned long ip, const char *fmt, ...);
 extern struct ftrace_event_call __start_ftrace_events[];
 extern struct ftrace_event_call __stop_ftrace_events[];
 
+extern const char *__start___trace_bprintk_fmt[];
+extern const char *__stop___trace_bprintk_fmt[];
+
+#define event_trace_printk(ip, fmt, args...)                            \
+do {                                                                    \
+        __trace_printk_check_format(fmt, ##args);                       \
+        tracing_record_cmdline(current);                                \
+        if (__builtin_constant_p(fmt)) {                                \
+                static const char *trace_printk_fmt                     \
+                  __attribute__((section("__trace_printk_fmt"))) =      \
+                        __builtin_constant_p(fmt) ? fmt : NULL;         \
+                                                                        \
+                __trace_bprintk(ip, trace_printk_fmt, ##args);          \
+        } else                                                          \
+                __trace_printk(ip, fmt, ##args);                        \
+} while (0)
+
 #endif /* _LINUX_KERNEL_TRACE_H */