tracing: add trace_bprintk()

Impact: add a generic printk() for tracing, like trace_printk()

trace_bprintk() uses the infrastructure to record events on ring_buffer.

[ fweisbec@gmail.com: ported to latest -tip, made it work if
  !CONFIG_MODULES, never free the format strings from modules
  because we can't keep track of them and conditionnaly create
  the ftrace format strings section (reported by Steven Rostedt) ]

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 0 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 22d7379709da..2dece104f9a1 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2158,6 +2158,12 @@ static noinline struct module *load_module(void __user *umod,
                                         &mod->num_tracepoints);
 #endif
 
+#ifdef CONFIG_TRACE_BPRINTK
+        mod->trace_bprintk_fmt_start = section_objs(hdr, sechdrs, secstrings,
+                        "__trace_bprintk_fmt", sizeof(char *),
+                        &mod->num_trace_bprintk_fmt);
+#endif
+
 #ifdef CONFIG_MODVERSIONS
         if ((mod->num_syms && !mod->crcs)
             || (mod->num_gpl_syms && !mod->gpl_crcs)