tracing: Add trace_puts() for even faster trace_printk() tracing

The trace_printk() is extremely fast and is very handy as it can be
used in any context (including NMIs!). But it still requires scanning
the fmt string for parsing the args. Even the trace_bprintk() requires
a scan to know what args will be saved, although it doesn't copy the
format string itself.

Several times trace_printk() has no args, and wastes cpu cycles scanning
the fmt string.

Adding trace_puts() allows the developer to use an even faster
tracing method that only saves the pointer to the string in the
ring buffer without doing any format parsing at all. This will
help remove even more of the "Heisenbug" effect, when debugging.

Also fixed up the F_printk()s for the ftrace internal bprint and print events.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 19 insertions, 4 deletions

diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index 4108e1250ca2..e2d027ac66a2 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -223,8 +223,8 @@ FTRACE_ENTRY(bprint, bprint_entry,
                 __dynamic_array(        u32,    buf     )
         ),
 
-        F_printk("%08lx fmt:%p",
-                 __entry->ip, __entry->fmt),
+        F_printk("%pf: %s",
+                 (void *)__entry->ip, __entry->fmt),
 
         FILTER_OTHER
 );
@@ -238,8 +238,23 @@ FTRACE_ENTRY(print, print_entry,
                 __dynamic_array(        char,   buf     )
         ),
 
-        F_printk("%08lx %s",
-                 __entry->ip, __entry->buf),
+        F_printk("%pf: %s",
+                 (void *)__entry->ip, __entry->buf),
+
+        FILTER_OTHER
+);
+
+FTRACE_ENTRY(bputs, bputs_entry,
+
+        TRACE_BPUTS,
+
+        F_STRUCT(
+                __field(        unsigned long,  ip      )
+                __field(        const char *,   str     )
+        ),
+
+        F_printk("%pf: %s",
+                 (void *)__entry->ip, __entry->str),
 
         FILTER_OTHER
 );