tracing/function-graph-tracer: drop the kernel_text_address check

When the function graph tracer picks a return address, it ensures this address
is really a kernel text one by calling __kernel_text_address()

Actually this path has never been taken.Its role was more likely to debug the tracer
on the beginning of its development but this function is wasteful since it is called
for every traced function.

The fault check is already sufficient.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/ftrace.c

@@ -491,13 +491,6 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
 		return;
 	}
 
-	if (unlikely(!__kernel_text_address(old))) {
-		ftrace_graph_stop();
-		*parent = old;
-		WARN_ON(1);
-		return;
-	}
-
 	calltime = cpu_clock(raw_smp_processor_id());
 
 	if (push_return_trace(old, calltime,

kernel/extable.c

@@ -41,7 +41,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
 	return e;
 }
 
-__notrace_funcgraph int core_kernel_text(unsigned long addr)
+int core_kernel_text(unsigned long addr)
 {
 	if (addr >= (unsigned long)_stext &&
 	    addr <= (unsigned long)_etext)
@@ -54,7 +54,7 @@ __notrace_funcgraph int core_kernel_text(unsigned long addr)
 	return 0;
 }
 
-__notrace_funcgraph int __kernel_text_address(unsigned long addr)
+int __kernel_text_address(unsigned long addr)
 {
 	if (core_kernel_text(addr))
 		return 1;

kernel/module.c

@@ -2735,7 +2735,7 @@ int is_module_address(unsigned long addr)
 
 
 /* Is this a valid kernel address? */
-__notrace_funcgraph struct module *__module_text_address(unsigned long addr)
+struct module *__module_text_address(unsigned long addr)
 {
 	struct module *mod;