[RFC PATCH 3/3] modules: tracing: Add module_text_offsets event

[Masami Hiramatsu (Google)]

From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Add new module_text_offsets event which records the offset of module
text and init_text section address and size.

This information is required for decoding the relative stacktrace
entries for modules.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
---
 include/trace/events/module.h |   40 ++++++++++++++++++++++++++++++++++++++++
 kernel/module/main.c          |    1 +
 2 files changed, 41 insertions(+)

diff --git a/include/trace/events/module.h b/include/trace/events/module.h
index e5a006be9dc6..1e5c84cc8d15 100644
--- a/include/trace/events/module.h
+++ b/include/trace/events/module.h
@@ -47,6 +47,46 @@ TRACE_EVENT(module_load,
 	TP_printk("%s %s", __get_str(name), show_module_flags(__entry->taints))
 );
 
+/* Module address offset from _stext */
+TRACE_EVENT(module_text_offsets,
+
+	TP_PROTO(struct module *mod),
+
+	TP_ARGS(mod),
+
+	TP_STRUCT__entry(
+		__string(	name,		mod->name	)
+		__field(	unsigned long,	text_offset	)
+		__field(	unsigned int,	text_size	)
+		__field(	unsigned long,	init_offset	)
+		__field(	unsigned int,	init_size	)
+	),
+
+	TP_fast_assign(
+		if (mod->mem[MOD_TEXT].size) {
+			__entry->text_offset = (unsigned long)mod->mem[MOD_TEXT].base
+					     - (unsigned long)_stext;
+			__entry->text_size = mod->mem[MOD_TEXT].size;
+		} else {
+			__entry->text_offset = 0;
+			__entry->text_size = 0;
+		}
+		if (mod->mem[MOD_INIT_TEXT].size) {
+			__entry->init_offset = (unsigned long)mod->mem[MOD_INIT_TEXT].base
+					     - (unsigned long)_stext;
+			__entry->init_size = mod->mem[MOD_INIT_TEXT].size;
+		} else {
+			__entry->init_offset = 0;
+			__entry->init_size = 0;
+		}
+		__assign_str(name);
+	),
+
+	TP_printk("%s text_offset=0x%lx text_size=%d init_offset=0x%lx init_size=%d",
+		  __get_str(name), __entry->text_offset, __entry->text_size,
+		  __entry->init_offset, __entry->init_size)
+);
+
 TRACE_EVENT(module_free,
 
 	TP_PROTO(struct module *mod),
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 5399c182b3cb..9f1ca8730a71 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -3372,6 +3372,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
 
 	/* Done! */
 	trace_module_load(mod);
+	trace_module_text_offsets(mod);
 
 	return do_init_module(mod);