ftrace: add checks on ret stack in function graph
Import: robustness checks
Add more checks in the function graph code to detect errors and
perhaps print out better information if a bug happens.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index d278ad2..f98c407 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -420,6 +420,15 @@
int index;
index = current->curr_ret_stack;
+
+ if (unlikely(index < 0)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ /* Might as well panic, otherwise we have no where to go */
+ *ret = (unsigned long)panic;
+ return;
+ }
+
*ret = current->ret_stack[index].ret;
trace->func = current->ret_stack[index].func;
trace->calltime = current->ret_stack[index].calltime;
@@ -427,6 +436,7 @@
trace->depth = index;
barrier();
current->curr_ret_stack--;
+
}
/*
@@ -442,6 +452,13 @@
trace.rettime = cpu_clock(raw_smp_processor_id());
ftrace_graph_return(&trace);
+ if (unlikely(!ret)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ /* Might as well panic. What else to do? */
+ ret = (unsigned long)panic;
+ }
+
return ret;
}