@@ -944,6 +944,7 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
unsigned long sp)
{
unsigned long return_hooker;
+ int bit;
if (unlikely(ftrace_graph_is_dead()))
goto out;
@@ -951,10 +952,16 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
goto out;
+ bit = ftrace_test_recursion_trylock(ip, parent);
+ if (bit < 0)
+ goto out;
+
return_hooker = ppc_function_entry(return_to_handler);
if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
parent = return_hooker;
+
+ ftrace_test_recursion_unlock(bit);
out:
return parent;
}
The function_graph_enter() does not provide any recursion protection. Add a protection in prepare_ftrace_return() in case function_graph_enter() calls something that gets function graph traced. Reported-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Fixes: 830213786c49 ("powerpc/ftrace: directly call of function graph tracer by ftrace caller") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/powerpc/kernel/trace/ftrace.c | 7 +++++++ 1 file changed, 7 insertions(+)