ftrace: Allow module init functions to be traced

Allow for module init sections to be traced as well as core kernel init
sections. Now that filtering modules functions can be stored, for when they
are loaded, it makes sense to be able to trace them.

Cc: Jessica Yu <jeyu@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Author: rostedt

include/linux/init.h

@@ -39,7 +39,7 @@
 
 /* These are for everybody (although not all archs will actually
    discard it in modules) */
-#define __init		__section(.init.text) __cold __inittrace __latent_entropy
+#define __init		__section(.init.text) __cold  __latent_entropy
 #define __initdata	__section(.init.data)
 #define __initconst	__section(.init.rodata)
 #define __exitdata	__section(.exit.data)
@@ -68,10 +68,8 @@
 
 #ifdef MODULE
 #define __exitused
-#define __inittrace notrace
 #else
 #define __exitused  __used
-#define __inittrace
 #endif
 
 #define __exit          __section(.exit.text) __exitused __cold notrace

kernel/module.c

@@ -3473,6 +3473,8 @@ static noinline int do_init_module(struct module *mod)
 	if (!mod->async_probe_requested && (current->flags & PF_USED_ASYNC))
 		async_synchronize_full();
 
+	ftrace_free_mem(mod->init_layout.base, mod->init_layout.base +
+			mod->init_layout.size);
 	mutex_lock(&module_mutex);
 	/* Drop initial reference. */
 	module_put(mod);

kernel/trace/ftrace.c

@@ -5752,7 +5752,8 @@ void ftrace_release_mod(struct module *mod)
 	last_pg = &ftrace_pages_start;
 	for (pg = ftrace_pages_start; pg; pg = *last_pg) {
 		rec = &pg->records[0];
-		if (within_module_core(rec->ip, mod)) {
+		if (within_module_core(rec->ip, mod) ||
+		    within_module_init(rec->ip, mod)) {
 			/*
 			 * As core pages are first, the first
 			 * page should never be a module page.
@@ -5821,7 +5822,8 @@ void ftrace_module_enable(struct module *mod)
 		 * not part of this module, then skip this pg,
 		 * which the "break" will do.
 		 */
-		if (!within_module_core(rec->ip, mod))
+		if (!within_module_core(rec->ip, mod) &&
+		    !within_module_init(rec->ip, mod))
 			break;
 
 		cnt = 0;